A Cured Meat Guide for Everyone

Meat Preserving And Curing Guide

The meat was originally processed to preserve it, but since the different procedures result in many changes in texture and flavor, it is also a way to add variety to the diet. Processing also makes it possible to mix the least desirable parts of the carcass with lean meat and is also a means of prolonging the meat supply by including other foodstuffs such as cereals in the product. extremely perishable product and quickly becomes unfit for consumption. may be hazardous to health due to microbial growth, chemical change and degradation by endogenous enzymes. These processes can be reduced by decreasing the temperature sufficiently to slow or inhibit the growth of microorganisms, by heating to destroy organisms and enzymes (cooking, canning) or by removal of water by drying or osmotic control (by binding water with salt or other substances so that it is no longer available for organizations). It is also possible to use chemicals to curb growth and, very recently, ionizing radiation (the latter possibility is not allowed in some countries, however). Traditional methods used for thousands of years involve drying by wind and sun, salting and smoking. Canning dates back to the beginning of the 19th century and preserves food for many years because it is sterilized and protected from further contamination. More here...

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Using membranes in food preservation

Membranes were first developed commercially as a means of purifying water by RO, and for purifying waste water. Applications in food processing have since widened considerably. Membrane techniques can contribute to food preservation in two ways. Firstly, membranes reject all micro-organisms within the retentate and thus the permeate will be sterile on production. Hence, provided that the relevant components of the food fluid permeate the membrane, then membrane processing can be used per se as a direct method of food preservation by reducing the number of micro-organisms in the feed. This approach is really limited to microfiltration. On the other hand, all the membrane processes contribute to concentration or fractionation procedures, which form part of other food preservation activities.

Food Preservation Through Control Of Water

Bound Water Food

As mentioned in the general discussion of food preservation, the most serious limitation of shelf life and nutritional quality is from microbiological activity. This section covers briefly the concept of reducing the amount of water in food systems as a means of food preservation. By lowering the amount of water available for microorganisms to remain active and reducing mobility of potentially reactive chemical species in a food system, it is possible to extend quality of a product from both a microbiological and nutritional point of view. Food preservation processes falling in this category include concentration processes such as evaporation or freeze-concentration dehydration including air drying, spray drying, freeze drying, and so on, and methods of adding salt or sugar and thereby lowering the available water by increasing osmotic pressure. Since all of these

High hydrostatic pressure technology in food preservation

In the context of food preservation, conventional thermal food processes are mostly used in the food industry. Recently, technologies have been developed to optimise the process (i.e., reducing the severity of the thermal processes leading to better food quality retention). Consumer requirements indicate the desire for high quality foods in the sense of more convenient, fresher, less heavily processed (e.g., processed with less heat), more natural, healthier and with less preservatives than foods that have previously been available. To respond to this situation, new and improved physical process techniques are being developed, for example, high hydrostatic pressure (HP) technology has the potential to produce foods that meet many of these consumer demands. This technique allows inactivating enzymes and microorganisms (vegetative cells) and at the same time offers advantages in minimal deleterious effects on food quality, e.g., colour, flavour, nutritional value. High pressure...

Food preservation and the development of microbial resistance

In this chapter we will discuss the origin of food preservation. We will take a historical perspective of the reasons why preservation is needed and will outline the current available techniques. We will then discuss food preservation in the context of food processing requirements and will touch a little on the concepts of microbial risk assessment as they are currently being laid down. We will go on highlighting novel developments in food preservation research, in particular the resistance of micro-organisms to (combined) food preservation treatments. Microbes react towards harmful environmental conditions by producing specialised stress metabolites and or proteins. These cellular reactions eventually may lead to preservation stress resistance and hence survival of unwanted microorganisms during food manufacturing and subsequently cause deterioration of the end-product in the food chain. In addition resistant microbes may change the microbial ecology of food manufacturing plants...

Methods of food preservation

The five basic historical methods of food preservation still in use today comprise desiccation or drying, heating, freezing, fermentation, and chemical preservation (Grierson, 1997). 4. Fermentation. Fermentation is a gradual chemical change caused by the enzymes of some bacteria, moulds, and yeasts. Fermented beverages were ubiquitous in the earliest civilisations of Mesopotamia and Egypt. Not only did wine facilitate conviviality, it was usually more potable than the available water. Winemaking also served as a means of storing nutrients from grapes almost indefinitely. Similarly, Asian steppe dwellers turned mare's milk into koumiss, a fermented beverage that keeps much longer than unprocessed milk. Many cheeses with a long shelf life are produced by lactic-acid fermentation. One means of pickling, a very early form of food preservation, is to treat foods with vinegar, a liquid obtained by further fermenting alcoholic beverages. 5. Chemical preservation. Many people consider food...

Instrumentation for monitoring the effectiveness of food preservation during processing

The effectiveness of food preservation techniques depends on the ability to monitor key safety parameters such as critical control points (CCPs) within HACCP systems. A similar systematic approach may be used to ensure essential quality, composition and labelling requirements or standards. As mentioned in 24.2.1 this approach is referred to as 'Defect Action Point (DAP) Analysis'. Monitoring may be continuous, or the frequency of measuring must be sufficient to guarantee that the CCP (or the DAP) is under control.

Food Preservation

Matching the supply of food as produced by the agricultural sector with the demand for food by consumers in both time and space necessitates the use of a variety of preservation techniques. Food is being produced in larger quantities by fewer people in rural areas often very distant from the urban consumer. The production of agricultural commodities follows cyclical patterns of supply, dictated by such things as cropping times and yearly fluctuations. The requirements on the food supply by the consumer include safety, quality, adequate shelf life, variety, and convenience. Thus, the demand for food tends to be more constant than its production, food needs to be transported from the production sector to the consuming markets, food needs to be transformed from its raw state as produced by the agricultural sector into a vast array of consumer goods, and throughout this process quality must be maintained, safety must be guaranteed, and the economics must be favorable, minimizing losses...

Combining antioxidants with other preservation techniques

The amount of antioxidants necessary for efficient stabilization may be reduced if food preservation by means of antioxidants is combined with another preservation technique. Cold storage is a typical example as the rate of free radical formation and thus also of antioxidant destruction is much lower under refrigeration. Refined rapeseed oil containing about 500 mg of tocopherols per kg is stable only for 2-4 weeks at 40 C, when the concentration of tocopherols approaches zero. If the same oil is stored at 10 C, no perceptible deterioration of sensory quality was observed even after 15 months of storage. On the contrary, frozen storage is not always preferable in foods containing water, such as meat or fish, as water crystallizes out of the hydrated protein layer protecting lipids against access of oxygen, and air has then free access to lipids. Natural antioxidants present are then rapidly consumed in spite of low temperature.

A S Meyer Technical University of Denmark

Then discussed in sections 4.3 and 4.4, respectively. In section 4.4.2 the focus is directed towards a number of other enzyme activities that have been explored for their antimicrobial effects. Section 4.5 summarises the reported combined effects of enzymatic and physicochemical factors and reviews novel techniques for improved antimicrobial potency of enzymes, with particular focus on lysozyme. Section 4.6 presents a brief introduction to the legislation on use of enzymes in foods, and gives a view on the future needs, trends and challenges in the practical exploitation of enzyme-based food preservation systems. Finally section 4.7 gives suggestions for further reading.

Effects of lysozyme in real food product trials

Akashi and Oono (1972) reported lysozyme to exert a weakly preservative effect in lightly salted fish, when lysozyme was employed as a dipping treatment in 1 gelatin-0.05 lysozyme solution, but treatment with sorbic acid consistently resulted in a better preservative effect than lysozyme in these fish products (Akashi and Oono, 1972). Later reports have confirmed that lysozyme exerts only weak antibacterial potency in animal products such as pork sausage (bratwurst) and Camembert cheese (Hughey et al., 1989). In Camembert cheese lysozyme by itself or together with EDTA reduced an inoculated L. monocytogenes population by ten-fold during the first 3-4 weeks of the ripening period, but the effect of lysozyme decreased with longer storage, where L. monocytogenes was found to grow unhindered in the artificially inoculated, lysozyme-containing cheeses (Hughey et al., 1989). A lysozyme dip treatment (3 mg mL) of cod fillets spiked with L. monocytogenes resulted in retarded growth of...

Combining traditional and new preservation techniques to control pathogens the case of E coli

Microbial food preservation methods currently employed involve such manipulation. As such, the safety of minimally processed foods relies on combined preservative factors, i.e., a combination of two or more agents being more inhibitory than any of the agents alone (the 'hurdle effect'). Combining inhibitory factors can result in a significant improvement in securing microbial safety and stability as well as the sensory and nutritional quality of foods. Recent research has focused on combining traditional inactivation, survival and growth-limiting factors at subinhibitory levels with emerging novel non-thermal intervention food preservation techniques using bacteriolytic enzymes (lysozyme), lactic cultures and culture products (e.g., bacteriocins), ionizing radiation, high hydrostatic pressure, or pulsed electric field (PEF). For example, the efficacy of high pressure is considerably enhanced when combined with heat, antimicrobials, or ionizing radiation. The effect of the combined...

Conclusions and future trends

Technologies employing combinations of existing and new preservation techniques to establish a series of preservative factors that microorganisms are unable to overcome are valuable tools and have enormous potential to improve the microbiological safety of minimally processed foods. The microorganism's physiological responses during food preservation are the basis for the application of these technologies. While microbial stress responses further complicate food preservation, the crucial phenomenon of food preservation is the homeostasis of microorganisms. Preservative factors functioning as hurdles can disturb one or more homeostasis mechanisms, thereby preventing microorganisms from multiplying and causing them to remain inactive or even die. Food preservation is in fact achieved by disturbing the homeostasis of microorganisms in foods, and the best way to do this is to deliberately disturb

General principles of membrane processing

There are several related separation processes incorporating membranes. Diafiltration is an extension of UF or MF and is discussed on pages 267-8. Electrodialysis is a combination of membrane and ion-exchange separation which can be used for demineralisation of food materials, reviewed by Grandison (1996b). Dialysis is a concentration-driven membrane separation, which has medical and biochemical applications, but is unlikely to contribute to food preservation. Similarly, pervaporation is the separation of liquid mixtures with a permselective membrane, but is unlikely to have food applications.

Microbial inactivation

Wavelengths ranging from 170 to 800 nm result in detrimental changes to microbial cell structures and functions. Thus, wavelengths in this range of 170800 are suitable for food preservation applications depending on the desired effect and the food equipment. The effects described below are generally observable when high-intensity light treatments are applied at wavelengths above 170 nm to product surfaces.

Effect of heat and pressure on ultrasound induced cell damage

The effectiveness of ultrasound in food preservation can be increased by combination with other treatments. The resistance of microorganisms and enzymes to ultrasound is very high and it may require several hours of ultrasonication to achieve the desired results. Such prolonged treatments will produce extensive changes in the food and the quality of treated food will be severely affected (Vercet et al., 2001b Villamiel et al., 1999 Miles et al., 1999 Vercet et al., 2002 Villamiel and de Jong, 2000a). Increased effectiveness of ultrasound preservation in combination with heat and pressure opens new possibilities. The use of ultrasound with moderate heating is known as thermosonication (TS). A combination of ultrasound and moderate pressure is known as manosonication (MS) and finally the full combination of heat, ultrasound irradiation and moderate pressure is known as manothermosonication (MTS) (Earnshaw et al, 1995 Sala et al, 1995 Earnshaw, 1998). MTS treatment facilitates the...

Ultrasound in combination with other preservation techniques

While the main research effort in food preservation using ultrasound has concentrated on either ultrasound alone, thermosonication or manothermosonication there are a range of studies which have examined ultrasound in combination with other techniques. Amongst these it is being employed in combination with disinfecting chemical agents including antibiotics, chlorine and ozone as an alternative synergistic method of pathogen destruction. There are also some studies of ultrasound in combination with freezing for improved food preservation.

In combination with ozone

Food and Drug Administration (FDA) granted ozone treatment GRAS status (Generally Regarded As Safe) for use as a method of preservation of bottled water. In order that ozone can be used as a method of food preservation the food processors must still apply for separate FDA approval. In August 2000 a broad-ranged petition for use of ozone as a method of food preservation within the meat, poultry, fruit and vegetable arena was filed with the FDA and a ruling is awaited. This will open up the way for widespread use of ozone throughout the food industry, for example, ozone saturated ice cubes for use in supermarket storage may become more commonplace. Ultrasound may be employed to inject the ozone into the water during the freezing process and the resultant ozone acts as an antibacterial agent. Ultrasonic ozone saturated water sprays have also been used by the food industry during various cleaning processes.

Preservation Of Food Through Osmotic Method

CHEFTEL, J C (1995) 'Review High pressure, microbial inactivation and food preservation', Food Science and Technology International, 1, 75-90. LEMAGUER, M (1988) 'Osmotic dehydration review and future directions', Symposium on Progress in Food Preservation Processes, Brussels, 1, 283-309.

Principles and technology

PEF processing for food preservation implies applying short electric pulses (usually 1-20 s, but with a range of 50 ns to several milliseconds) with a high field strength (15-80 kV cm ) to samples placed between two electrodes in a batch or continuous treatment chamber. To generate such a fast electrical discharge, different kinds of pulse-forming networks (PFN) are used. The main components of a PFN are

With a bactericide in surface cleaning

The use of ultraviolet light as an aid to disinfection and to aid food preservation is well known and well used within the food industry. Ultraviolet light has been used to inactivate Salmonella in thin aqueous and chocolate films (Lee et al., 1989). They compared the results obtained with those from the use of ultrasound as a method to inactivate the bacteria. Serotypes such as the heat-sensitive S. eastbourne to the less sensitive S. senftenberg were examined. They discovered that the thermal resistance of salmonella was greater in the chocolate than in the aqueous media. Decimal reduction times at 710C were 4.5 hrs, 4.6 hrs and 6.6 hrs for thermal treatment of S. eastbourne, S. senftenberg and S. typhimurium serotypes. Using ultrasound a 4log10 reduction was observed at 50C after only 10 minutes sonication in peptone water whilst a 0.78log10 reduction of the bacteria was observed in milk chocolate after 30 minutes. High temperatures were observed in the chocolate medium and this...

Using MAP and other techniques to preserve fresh and minimally processed produce

For the produce whose shelf life cannot be sufficiently extended by MAP and refrigerated storage, the use of other preservation technologies in combination with MAP should be explored. 0ne promising technology is irradiation. However, the use of irradiation for food preservation is currently approved only by some countries and only for a limited number of products or produce. Recently, Canada has proposed the extension of the list of food that can be irradiated to include fresh and frozen ground beef, fresh and frozen poultry, prepackaged fresh, frozen, prepared and dried shrimp and prawns, and mangoes (FoodNavigator.com, 2002). The use of MAP in conjunction with irradiation may become the technology of choice for much fresh produce in the future.

Ultrasonic inactivation of microorganisms spores and enzymes

Ultrasonic Food Preservation

There are many examples of microorganisms inactivated using ultrasound (Table 16.4). Some of these have been studied in culture media and others in food. The most frequently studied microorganisms, not only in the field of power ultrasound, but also among other methods of food preservation are Saccaromyces cerevisiae and Escherichia coli. The former has been found to be less resistant to ultrasound than other vegetative cells, which is mostly attributed to its larger size. The inactivation of this microorganism has been proven in such food models as water, phosphate buffers, and sabouraud broth (Sala et al, 1995, Ciccolini et al., 1997 Guerrero et al., 2001 Petin et al., 1999 Lopez-Malo et al., 1999). Examples of inactivation studies of Escherichia coli cells include investigations of suspensions in a variety of media under different treatment conditions including frequency, power, heat and the presence of dissolved gases (Burleson et al., 1975 Hua and Thompson, 2000 Peterson and...

Ultrasound as a preservation technology

Nowadays ultrasonic technology is much more commonplace, costs have reduced and applications have become economically viable. The various effects of cavitation outlined in section 16.2 can be utilised in food preservation. Applications include the long-established surface cleaning where the powerful jet generated on collapse will dislodge dirt and bacteria from surfaces. The particular advantage of ultrasonic cleaning in this context is that it can reach crevices that are not easily reached by conventional cleaning methods. Once dislodged into the bulk solution any harmful species are subject to ultrasonically assisted disinfection. In solution ultrasound can be of great use in the general sterilisation and disinfection of food materials particularly where ultrasound is used in conjunction with a conventional sterilisation technology, e.g., heat or the use of a biocide. Research studies to date have focused on a range of different experimental procedures, and biological systems to...

Unwanted microorganisms in food manufacturing

Problems with food spoilage and food-borne diseases must have been a continuous preoccupation of early humans, once they began their hunting and food-gathering activities, and domestic production of food animals and crops. Although the exact timing is uncertain, organised food production probably started between 18,300 and 17,000 years ago, when barley production is said to have flourished in the Egyptian Nile Valley (Wendorf et al., 1979). Some foods were treated with honey and later with olive oil (Toussaint-Samat, 1992). This led to the development of additional preservative measures, such as heating and salting. The situation changed after 1795, when the French government, driven by war, offered a substantial reward for anyone developing a new method of preserving food. It was Nicholas Appert, a Parisian confectioner, who accepted the challenge and developed a wide-mouth glass bottle that was filled with food, corked and heated in boiling water for about six hours. In 1810, Durand...

Preservation techniques and food safety

Food preservation systems have to function in the context of the total food chain. In that respect it is crucial to apply the Hazard Analysis and Critical Control Points (HACCP) concept. This is a systematic approach to the identification, assessment and control of hazards in a particular food operation. It aims to identify problems before they occur and establish measures for their control at stages in production that are critical to ensuring the safety of food. Control is proactive, since remedial action is taken in advance of problems occurring. The

Understanding the heterogeneity in stress resistance in microbial populations at the molecular level

Food spoilage organisms are confronted with various forms of stress. As discussed extensively, the environment may change in terms of water availability, acidity, temperature profile, presence of antimicrobial compounds (preservatives), absence of nutrients, etc. Similar to other biological systems, microbial populations of relevance to the food chain also generally respond non-homogeneously to stress conditions (Peleg and Cole, 1998). Differences may be due to cell age, state of the cell cycle, but also to stochastic variations in exact molecular cellular composition (discussed in Sumner and Avery, 2002). McAdams and Arkin (1997) analysed the distribution of transcription factors over cells in a given population. It was shown that the transcript concentration can frequently be low to very low (theoretically to significantly below one copy per cell). These observations imply that stochastic variations in the concentrations of transcription factors may contribute significantly to the...

Predictive modelling of stress adaptation what will be the future role of metabolomics transcriptomics and proteomics

This integration of molecular microbiology and classical physiology into what is now often called functional genomics is we believe the major challenge and driving force for future research both in biology in general and in food preservation in particular. This view is shared with other leading food researchers as is reflected by the papers of Desiere et al. (2002) and Weimer and Mills (2002) in the context of the American Institute for Food Technologists.

Preservation process modelling prospectives

Finally, the current scientific developments also facilitate the construction of tools that allow for tracing and tracking of micro-organisms through the whole food chain based on their physiological and molecular ecological characteristics. Currently, projects have been and are being defined in order to obtain a transparent view of the food chain with respect to microbial food spoilage and resistance development against food preservation techniques. These projects are joint efforts by academia, research institutes and major multinational food processing companies including Nestl and Unilever. It will be these public-private consortia that we expect to see moving forward with the right practical focus and the required speed whilst ensuring incorporation of state-of-the art new scientific and technological developments.

Combining traditional and new preservation techniques

The use of high pressure in combination with mild heat is promising (Patterson, et al., 1995a). This strategy is successful because there is evidence that microbial injury can occur at significantly lower pressures than that required for inactivation (Patterson et al., 1995b). E. coli cells surviving pressurization become sublethally injured and develop sensitivity to physical and chemical environments to which the normal cells are resistant (Kalchayanand et al., 1998a Hauben et al., 1996). This suggests that exposing E. coli to a combination of different intervention strategies renders the bacterium sublethally injured and serves as an effective food preservation method. Hauben et al. (1996) assessed the destruction and sublethal injury of E. coli by hydrostatic pressure and by combinations of high pressure treatments with lysozyme, nisin, and or EDTA. High pressure treatments (180 to 320 MPa) disrupt the bacterial cells outer membrane, causing periplasmic leakage and sensitization...

Process and equipment

Some factors that impact the type of equipment needed to achieve food preservation with high-intensity light are ozone build up, surface area of the food product and dimensions of each treatment unit and desired degree of decontamination.9 A product that requires a specified temperature, during processing10 to maintain optimal quality, may require a model of high-intensity light equipment that is fitted with a cooling unit (Fig. 15.5). For example, McGregor et al. (1998) developed a power light source equipment suitable for inactivation of microorganisms by utilizing a clear quartz tube filled within Xenon and subjected to 100 W of power.11 This lamp equipment was attached to an inverting Marx pulse generator with a charge of 30kVdc (U.S. Food and Food processing engineers and food scientists recognize that microbial inactivation is not the only issue when designing high-intensity and UV light irradiation equipment for foods. Designers of equipment used for food products must take...

Problems in combining traditional preservation techniques

It is logical to consider the stress responses of E. coli in the context of food formulation factors that have systematically been demonstrated to affect growth and survival in food systems. Food preservation factors, such as temperature, aw, pH, etc., constitute environmental stresses to bacteria. If the stress is mild, it causes injury to the bacteria and if it is severe, it causes inactivation. Injured bacteria in food are of concern, since they can survive when favorable conditions are encountered, as well as multiply and grow in food. As consumers demand enhanced freshness and appeal, minimal processing is employed in which mild treatments are applied to the food products. As such, the bacteria are exposed to mild stress, which can induce resistance responses and compromise the safety and shelf-life of these food products. According to Gould (1995), homeostasis and stress reactions enable microorganisms to keep important physiological systems operating, in balance, and...

Other concentration and separation processes

The application of the full range of membrane processes has been investigated in all sectors of the food processing industries, and detailed reviews can be found elsewhere (e.g., Cheryan 1998 Lewis 1996a and b Kosikowski 1986). This section will take an overview of selected applications to illustrate the breadth and scope of the techniques as contributors to food preservation. Membranes are widely incorporated into fermentation or enzyme reactors in the biotechnology industries, UF or MF membranes being effective means of immobilising enzymes or cells and thus permitting continuous processing. This type of application will not be discussed further here.

Osmotic stress and osmoregulation in microorganisms

From the microbiological point of view, food preservation implies exposing the microorganisms to a hostile environment (i.e., to one or more adverse factors) to prevent or delay their growth, shorten their survival or cause their death. Unfortunately, microorganisms have evolved different mechanisms to resist the effects of these environmental stress factors. Internal media stability (composition and volume of fluids) is vital for survival and growth. This stability or homeostasis is maintained through feedback mechanisms that act in response to relatively minor changes in physiological variables, leading to a series of events that will in turn restore the altered variable to its original value (Gould, 1996). These mechanisms, called 'homeostatic mechanisms', act to ensure that key physiological activities and parameters in the microorganisms remain relatively unchanged, even when the environment around the cell is different and greatly perturbed (Leistner and Gould, 2002). In the...

Combining control of water activity with other preservation techniques

The most important techniques commonly used in food preservation act by inhibiting the growth of microorganisms rather than by inactivating them (Gould, 1995). Among the inhibitory techniques are As stated by Leistner (1978, 1987) it soon became apparent that in most foods for which aw is important for quality and stability, other factors, referred to by Leistner as 'hurdles', contribute to the desired product, and the interest taken initially in aw for food manufacturers was extended to other factors (e.g., Eh, pH, temperature, incorporation of additives, etc.). The goal was to obtain stable products based on an intelligent combination of factors by combination preservation technology or hurdle technology. More than 60 potential hurdles for foods of animal or plant origin, which improve the stability and or quality of these products, have been already described, and the list of possible hurdles for food preservation is by no means complete (Leistner, 2000).

Applications for the stabilization of lard and meat products

Smoke is traditionally used as a preservative for meat products. Smoke preparations from ash and beech wood are rich in phenolics so that they may prolong the stability of lard or pork meat, which is important in the production of smoked meat products. Sodium nitrite, added in curing preparations, inhibits the oxidation of pork meat, but its activity decreases with increasing cooking time as it reacts with other meat components. The antioxidant activity was higher in cooked ground pork and beef treated with nitrite, during cold storage, compared to untreated meat (Zubillaga and Marker, 1987). Maillard products also protect sausages against oxidative degradation during frozen storage (Lingnert and Lundgren, 1980) and in cookies (Lingnert, 1980). The antioxidant activity of soy sauce in ground pork fat patties is probably due to free amino acids present in soy sauce.

Effect of acidulante

Propionic, sorbic and benzoic acids are classified by food legislators as 'preservatives' rather than 'acidulants', e.g., in Annex III to EU Directive 95 2. In foods manufactured with the addition of vinegar, acetic acid acts both as a source of external hydrogen ions and as a proton carrier though the membranes. However, because acetic acid is a natural metabolite in human metabolism and because it has been used in food preservation for thousands of years (see Adams, 1998), it is not classified as a food preservative in EU Directive 95 2. There are strict limitations on the use of weak lipophilic organic acids in food preservation. In many foods, only low levels of acetic acid are tolerated sensorially. Limits on the use of propionate, sorbate and benzoate are set by sensory criteria, by legislation and by the poor acceptance of 'chemically' preserved food by consumers.

Preservatives

Most preservatives are weak acids active in their undissociated forms. As pH is lowered, the percentage of this form and thus the antimicrobial activity increases. In the pH range of most cured meats, relevant equilibrium levels of nitrous acid (pKa 3.36) are formed from nitrite. Unlike weak organic acids, nitrous acid perturbs energy-yielding reactions directly by reacting with iron involved in electron transport systems (heme iron in the respiratory chain, non-heme iron in ferredoxin and in pyruvate ferredoxin oxidoreductase, factors essential for clostridial energy metabolism Cammack et al., 1999).

Sodium chloride

The effect of sodium chloride in combination with other factors on E. coli has been investigated. The combination of reduced pH (to pH 4.5) and increased salt concentration (5 NaCl) inhibited growth of the pathogen at 22 0C in a beef gravy medium simulating fermented dried meat (Uyttendaele et al., 2001). Gibson and Roberts (1986) examined the combined effects of pH, temperature, NaCl, and NaN02 on the growth of 10 pathogenic strains of E. coli and reported that the maximum NaCl concentration that permitted growth was 6 at pH values between 5.6 and 6.8 and temperatures between 15 and 300C. In this latter study, growth occurred in any combination of 0 to 4 NaCl and 0 to 400mg l of NaN02 at pH values between 6.2 and 6.8 and temperatures between 15 and 35 0C. However, a concentration of 8 or more of sodium chloride completely inhibited growth of enteropathogenic E. coli at different temperature and pH levels, while a concentration of 4 in combination with pH 5.6 and 200 ppm of nitrite...

Conclusions

The US Food and Drug Administration examined ultrasound as a basis for use in the food industry. Their conclusions were that ultrasound used alone was insufficient to inactivate many bacterial species and would therefore not be effective as a method of food preservation alone. However, it had, in some cases, synergistic effects with other methods of food preservation and as such could be explored for its potential as a significant aid to food preservation techniques. Unfortunately, one of the major problems in writing a chapter such as this is that it is well known that several large food and drink companies do have significant investment in ultrasound but, unfortunately, none of them is willing to reveal details of their work.

Thermometers

Temperature is very often the most important parameter in food preservation. This is especially the case in heat preservation (see Chapters 9 and 10), where the heating process must result in a certain temperature for a certain time in the centre (the coldest point) of the product. The thermal process for each product (in each container) must be specified, including information on heating-up time, cooking time and temperature, cooling rate and time, etc. This is established by means of a heat penetration test, in which the temperature at the centre of the product is monitored during thermal processing in order to calculate the sterilising pasteurising effect. As heat penetration during heating in water or steam is well known, this is fairly simple. In order to monitor the heating process, it is necessary to monitor the temperature in the water or steam, and this is normally done continuously, i.e., measuring and recording the temperature at least once every minute. The accuracy of...

Highintensity light

High-intensity light, also described as pulsed broad-spectrum white light, is a decontamination or sterilization technology that can be used for the rapid inactivation of microorganisms on food surfaces, equipment and food packaging materials. Surface decontamination of food products using pulsed high-intensity light has many potential benefits to the food industry. High-intensity light is a non-thermal food preservation intervention, with the ability to minimize the deleterious effects of thermal processing and chemical treatments on quality and sensory attributes. Two additional advantages of this technology are, first, it is cost effective, with minimal operating and maintenance costs once equipment is in place and secondly, it is regarded as a relatively safe and non-toxic treatment. Data submitted to the Food and Drug Administration (FDA) of the United States, for approval of UV light treatments for fruit juices, supports the claim that broad-spectrum white light provides...

Preface to the First Edition

Part IV deals with the role of fats and oils in overall nutrition. The importance of antioxidants in nutrition and food preservation is presented. Excess fat intake is associated with many disease conditions. This section describes various omega fatty acids and their sources, the role of dietary fats in atherosclerosis, eicosanoids production, immune system, coronary heart disease and obesity. The various types of lipid-based synthetic fat substitutes are discussed.

Antimicrobial Compounds

Food antimicrobials are chemical compounds added to or present in foods for the purpose of retarding microbial growth or killing microorganisms. The major targets for antimicrobials are bacteria, molds, and yeasts that are either pathogenic or cause spoilage of foods. The effectiveness of food antimicrobials against viruses and parasites carried by foods is less well characterized. Food antimicrobials are sometimes referred to as food preservatives however, the latter include food additives that are antimicrobials, antibrowning agents, and antioxidants. Under normal use conditions, food antimicrobials are bacteriostatic or fungistatic rather than bactericidal or fungicidal. The former indicates inhibition of growth of cells while the latter indicates killing of a population. Bacteriostasis is often reversible. Because food antimicrobials are generally static in nature, they will not preserve a food indefinitely. Depending on storage conditions, the food product eventually spoils or...

Classification of Bacteria

Bacteria are now classified into two major groups, the Eubacteria and the Archaebacteria (which were formerly grouped under the Protista). The majority of bacteria involved with food systems are Eubacteria. The Archaebacteria presently house the unique halobacteria, which are obligate halophiles and can cause the red tainting of salted fish. All bacteria fall into two convenient groups, those that stain purple with the Gram stain (Gram-positive) and those that stain red with the Gram stain (Gram-negative). In Gram-positive bacteria, there is a bi-lipid membrane between the cell wall and cytoplasm, with the cell wall consisting mainly of peptidoglycan linked with teichoic acids. The cell envelope of Gram-negative bacteria is more complex, consisting of three layers, often referred to collectively as the sacculus. The innermost layer (i.e., the inner cytoplasmic membrane) is adhered to the peptidoglycan layer (otherwise referred to as the murein sacculus (7)), which is covalently linked...

Scurvy The History and Discovery of Vitamin C

Foods (wheat flour and oatmeal), salted meat, dried peas, cheese, butter, and ale, i.e., whatever could be dried and preserved, often for long periods in adverse tropical climates. The signs and symptoms that were commonly described in classical accounts of scurvy, written long before its cause was understood, included lassitude, swollen joints, putrid and bleeding gums, failure of wound healing and the opening of old wounds and sores, intradermal bleeding due to capillary fragility, heart failure, and sudden death (Table 2). Although nowadays we carefully distinguish the symptoms of true scurvy (now known to be produced specifically by vitamin C deficiency) from conditions such as beriberi (thia-mine deficiency, which is associated with oedema of the lower limbs), vitamin A deficiency (associated with night-blindness and corneal lesions), and rickets (caused mainly by a lack of exposure to sunlight in children), in the older literature these conditions were often not recognized as...

Fermentation In Food Biotechnology

Fermentation is an important part of our lives. The relevance of fermentation to day to day life is evident from the fact that food can be both spoiled and made by fermentation. Many of the foods used for human consumption are fermented foods. Fermentation is one of the oldest techniques used for food preservation. Muscle cells use fermentation to provide energy for a quick response. The oldest food biotechnological processes include the baking of yeast leavened breads, brewing of beer, sake and wine, and production of yogurt and cheese. Biotechnology can improve the baking process with improvements in cereal grains and starter culture through recombinant DNA technology, use of enzymes as processing aids, and application of advanced batch and continuous fermentation technologies (3). Brewing is regarded as a typical example of traditional or old biotechnology, because of its long history (4). Preservation of food remains one of the major objectives of fermentation. In addition, there...

Cultural Overview

The traditional method of hunting bison was to drive a herd into a corral built against a bluff or at the end of a ravine. Corrals continued to be used until the extermination of wild bison in the 1870s, although pursuit from horseback was an alternative method for the final century of Blackfoot independence. Once the bison had been slaughtered in a corral, teams of six (men and women) butchered the kill. Hides were tanned for tipi covers, winter robes, and bedding. The meat was sliced thin and air-dried for preservation. Pounding dried meat with berries and rendered fat made pemmican, a highly nutritious compact food that could be stored in hide bags for months. Bison bones were made into cutting blades, scrapers, and tool handles. Bison wool could be spun and woven, although historically Blackfoot preferred to purchase woven bags from neighboring nations and cloth from European traders. Blackfoot made pottery before the European trade introduced more durable metal kettles.

Fish And Shellfish Products The Seafood Chain

It is known that humans have used rather advanced techniques for obtaining and processing seafood throughout recorded history. A main source of protein for the ancient Egyptians was fish from the Nile, Mediterranean, and pond culture. Fish was consumed fresh and salted for preservation by the Greeks. Dried fish became a major source of animal protein in Europe when the Roman church banned meat consumption on Fridays and during Lent.

Cultural Construction of Gender

Oral lore and linguistic conventions continually draw a symbolic boundary between men and women. These include proverbs commonly recited in a jesting fashion by the opposite sex when observing others engaged in some strenuous activity. Thus a man butchering a moose or caribou who cannot remove a hindquarter or forequarter with one well-placed cut from his knife is judged not ready for marriage. More ominously, a wife who pokes a hole in the thin-cut sheets when preparing smoke-dried meat is deemed fit to be killed by her husband (Jarvenpa, 1999). During middle age, a married couple focused their energies upon raising their children into their apprenticeship years when the latter's assistance in providing a livelihood for the family became increasingly significant. Another major concern of middle-aged Chipewyan was finding good marriage partners for their young adult children from compatible families who would become sources of helpful in-laws during stressful times of need. As...

Degradation Turnover and Factors that Induce Increased Requirements for Vitamin C

The instability of vitamin C in air, and especially in neutral or alkaline aqueous solution, is attributable to the fact that in the presence of oxygen or other oxidizing agents it readily undergoes two successive one-electron oxidation steps to produce dehydro-ascorbate. Since the oxidation products are also unstable and undergo an irreversible lactone ring opening to diketogulonic acid, the vitamin is very easily destroyed, both in foods and (to a lesser extent because of efficient recycling mechanisms) in the body. Diketogulonic acid is one of several degradation products of vitamin C that cannot be reconverted to the vitamin and are further degraded to stable excretory products, such as oxalic acid, by oxidative metabolism. Of all the micronutrients that are essential for human health and survival, vitamin C is the most easily destroyed during drying and other traditional methods of preserving food. Citrus fruits contain other organic acids that inhibit this process of oxidation...

Foodprocessing Facilities

Certain food products are highly perishable, have marginal value, or have only regional acceptance. Dairy products, bread, soft drinks, beer, glass-packed items, and certain cured-meat products are usually manufactured from more stable raw materials or are locally produced starting materials and are distributed daily. With such distribution, production schedules are determined by local weather forecasts, by day of the week and holidays, and by seasonal factors so that returns of stale or overage products can be minimized. Considerable progress has been made in the analysis of perishable food distribution practices. A universal product code applicable to all processed foods for retail sale has further improved distribution efficiencies by allowing automatic retail checkout and continuous inventory review.

Food Science And Technology Definition And Development

Food science and technology arose as separate disciplines through the coalescing of those portions of other sciences that dealt with foods. Traditionally, chemists, microbiologists, and other kinds of scientists studied or taught about foods from their particular points of view, but food processing transcends any one of the traditional disciplines. The distinction between chemists and microbiologists who study foods and food scientists and technologists is that the former devote their efforts chiefly to determining chemical composition, or the microbial state of foods. They are concerned with only one aspect of food. There is a need for those whose vision and competency cuts across discipline lines. When food processing is involved, knowledge of only one branch of science is not enough. There is a need for scientists and technologists whose knowledge of the different fields germane to various aspects of food preservation enables them to couple principles from the traditional fields...

Freezing Systems For The Food Industry Fundamentals

The purpose of all food preservation methods is to inhibit or decrease the speed of reaction responsible for the deterioration. All of these reactions are among other factors influenced by temperature. The speed of reaction is decreased at lower temperatures. Cooling and chill storage therefore are perhaps the most important methods of enhancing the storage life of most food products. But even at temperatures near the freezing point some reactions, including growth of many microorganisms, continue at a rate that will limit the preservability to a relatively short period of time.

Fermented Fish Products

(a) Japanese katsuobushi This is made from fish and used for seasoning. A. glaucus is involved in the fermentation (Graikoski 1973) (b) Cambodian Phaak or Mamchas This is a fermented paste produced from eviscerated salted fish. Glutinous rice pretreated with yeast is also added to the fish (Padmaja and George 1999) (c) Vietnamese Nuoc-mam This is a brown liquid produced by fermentation of small marine or fresh water fish that are placed in earthenware vessels buried in the ground for several months. Bacteria and yeasts contribute to proteolysis and flavor. Enzymes from A. oryzae can be used for reduced fermentation time to increase yield of nuoc-mam (Richard 1959).

Origin Botanical Facts

Roots that are firm and free of blemishes should be selected. The root can be refrigerated in a plastic bag for up to a week. Usually grated and used raw, the root must be washed, scrubbed, and peeled before grating by hand or with a food processor. Vinegar or lemon juice can be added to the grated horseradish to retard the enzyme process that produces the distinctive bite. For a mild sauce, 2 to 3 tablespoons of lemon juice or vinegar can be added to a cup of horseradish along with a half teaspoon of salt immediately after grating. For a hot sauce, the grated horseradish should be allowed to stand a few minutes before the lemon juice or vinegar is added. Because heat causes the root to release a pungent smell, horseradish should never be cooked. Grated horseradish is used as a condiment on fish, beef, chicken, and sausages. It is usually combined with oil and vinegar or with cream to make sauces for beef, smoked fish, or asparagus. Horseradish is the ingredient that provides the...

Highpressure Processing

Consumers are shifting their food purchases from heat-processed to fresh-tasting, minimally processed foods since excessive heat treatment can reduce the perceived freshness of foods. Salads, fruits, vegetables, nuts, spices, oysters, and selected cheeses are traditionally consumed without heat treatment. However, the incidence of pathogenic microbes is increasing in minimally processed and in raw foods previously considered safe. Escherichia coli 0157 H7 has been found in fresh apple and orange juice. This has caused the U.S. Food and Drug Administration (FDA) to recommend pasteurization. High-pressure processing (HPP) is one alternative to heat to achieve the pasteurization or commercial sterility of many fresh and freshlike processed foods. An advantage of HPP is that the treatment does not break covalent bonds. As a result, HPP does not change the flavor, color, or nutrient content of the food. Heat and ionizing radiation break covalent bonds as a function of dose and thus have...

Introduction the development of thermal processing

Thermal processing is one of the conventional preservation methods which assures processed foods to be safe and shelf-stable. The origin of commercial thermal processing dates back to 1809 when the Frenchman Nicholas Appert was awarded a prize by the French government for developing a new and successful means of preserving foods, a method that eventually became known as 'canning'. Appert found a new and effective way to preserve food, but did not understand why it prevented food spoilage. In 1864, Louis Pasteur, another Frenchman, explained that the heating process killed (or inactivated) the microorganisms which limited the shelf-life of foods. This laid the foundation for advances in canning methods that eventually revolutionized the industry. In the 1890s, Prescott and Underwood established the relationship between thermophilic bacteria and the spoilage of canned corn. At about the same time, the same type of spoilage was discovered in canned peas by Russell in Wisconsin and Barlow...

Organoleptic Description Of Spoilage

Changes in the visual, tactile, olfactory, and flavor characteristics of food constitute spoilage, symptoms varying with the commodity. As an aid to summarize the types of spoilage occurring in many of the major food commodities, Table 1 lists some of these spoilage descriptors and the associated factor mechanism for their development. Examples of visual changes would include the surface darkening of red meats, greening of cooked and cured meats, surface darkening of cut fruits, and fuzzy areas being generated on the surface of fruit, bread, or cheese. Other visual changes that also overlap tactile perceptions include sliminess on meats and vegetables and ropiness and curdling in fluid milk products. Off-odors and off-flavors associated with spoiled foods may be described by the terms putrid, rancid, bitter, soapy, sour, stale, and earthy. These off-odors and off-flavors vary not only between food categories but may also vary within a food category. For instance, the spoilage of...

Evaporated Milk History

Evaporated milk, like other processed canned foods, originated with the experiments of the French scientist Nicholas Appert. Appert, whose work on food preservation began in 1795, was the first to evaporate milk by boiling it in an open container and preserve it by heating the product in a sealed container. Fifty years later, Louis Pasteur laid the scientific foundation for heat preservation by demon

Food Storage And Prediction Of Shelf Life

Quality deterioration in the form of decrease of nutritional value, color change, development of off-flavor, and textural change may occur in foods during storage. The purpose of food preservation is to minimize such quality deterioration. To provide adequate but not excess protection, the studies of environmental factors affecting quality deterioration are of prime importance. To predict quality changes, or to predict shelf life of foods, kinetics studies of essential parameters, such as product characteristics, storage environment, and container protection are necessary. Computer-aided simulation of models derived from such kinetics studies can provide information for adequate design of a preservation scheme for foods and also for prediction of the shelf life of foods (39-43). The success of such design and prediction depends mainly on the understanding of the nature of the chemical and physical changes of the food system involved and the subsequent derivation of a correct kinetics...

Applications Of Hurdle Technology

The intelligent application of hurdle technology for a mild but efficient food preservation is advancing worldwide in industrialized as well as in developing countries. Some examples and trends are presented next. Deliberate and intelligent hurdle technology for food preservation started about 20 years ago in Germany with meat products. First it was used for the gentle preservation of mildly heated, freshlike meats storable without refrigeration (4). In the meantime, several categories of these shelf-stable meat products have evolved, which are in large quantities on the German market and have caused no problems related to spoilage or food poisoning. In the manufacturing plants, processing these shelf-stable meats requires no microbiological tests to be carried out however, other process parameters have to be strictly controlled these are time, temperature, pH, and aw (15). Furthermore, a better understanding of the sequence of hurdles that leads to microbial stability of fermented...

Influence of food processing practices and technologies on consumerpathogen interactions

This chapter will cover the role of food processing in increasing or decreasing contamination, growth and survival of pathogens in food. There is a long history of preservation of foods however, the science behind the safety of food preservation is relatively new, as is noted in Section 5.2. Section 5.3 addresses how science and technology have influenced production and manufacturing processes, including the impact of the adoption of the Hazard Analysis and Critical Control Point (HACCP) system in the food manufacturing sector. Section 5.3 also describes how foodborne illness outbreaks and new surveillance strategies have resulted in the development of new food safety control measures. Section 5.4 describes how consumer preferences can sometimes have a negative impact on public health, when preservation systems are reduced to meet

Historical perspective on food processing Roman sausage to canning to space food

Early humans were hunters and gatherers. Getting food was a daily process, and food spoilage and foodborne illnesses must have been common. Agricultural production of grains and animal husbandry followed the hunting gathering stage, although hunting and gathering remained common means of obtaining food. Early forms of preservation such as salting, drying, smoking and fermenting were practiced long before people understood why they worked, and were likely discovered by accident. Although food safety was probably not at the forefront of early man's concern when they were just trying to get enough food to survive, these food preservation techniques that inhibited food spoilage microorganisms had the added benefit of inhibiting many pathogenic organisms. Early attempts at fermentation were probably especially fraught with dangers. Clostridium botulinum is derived from the Latin term botulus, meaning sausage. The 'controlled spoilage' under the specific conditions of fermentation allows...

Interaction Of Factors

The level of a single growth-limiting factor that will inhibit a microorganism is usually determined under conditions in which all other factors are optimum. In preserving foods more that one factor is usually relied upon to control microbial growth. Addition of a substance, which in itself does not give full inhibition, can effectively preserve products in the presence of other subinhibitory factors. The effect of superimposing limiting factors is known as the hurdles concept (Leistner 1999).

The First Of The Teaching Departments

Just a little bit earlier than investigations such as that of the NCA, universities began to teach phases of food preservation that would be called food science today. Dairy processing and meats processing were taught during the nineteenth century, but the subject matter of each tended to be taught from the point of view of that commodity alone. In the 1910s things changed. At four different universities, predecessor departments to food science and technology arose. Like dairy manufacturers, their first departmental names were descriptive of the commodity area that they represented, but the pioneer teachers of food preservation recognized that the principles and facts that applied to their products had application to other commodities thus, they tended to broaden their approach by teaching food preservation across commodity and discipline lines. At the University of Massachusetts, the departmental designation was Horticultural Manufacturers at the University of California, it was...

Trehalose In Plants And Drosophila

Utilization of trehalose as an additive for food preservation or storage has recently become feasible through the development of new techniques enabling economical large scale production from starch (24,29). The sugar's mild sweetness 45 that of sucrose (29) and masking effect of bitter-tasting compounds, as well as lack of an aftertaste or laxative effect, enhance its versatility as a contributor to the texture and balance of flavors in foods (90). It is not easily degraded during processing, and its resistance to taking up moisture reduces caking in mixtures with other ingredients (29). The protective effects of trehalose prolong the shelf life of starch-containing products by preventing retrogradation, as noted similarly, the stabilization of proteins and lipids during freezing and drying extends the shelf life of products containing eggs or meat (29).

Foodpreservation Techniques

Food-preservation techniques can be grouped under drying, low-temperature freeze-drying, high-temperature, radiation, and chemical treatments. The technologies of these processes are recorded in other articles in this encyclopedia. In this article only their effects on microorganisms are discussed. Drying is the most widely used method of food preservation in the world. Meat, fish, cereals, fruits, and vegetables are dried and preserved for a long time. Controlled dehydration and sun drying of foods removes water from foods so that microorganisms cannot grow. This process does not sterilize the food, so when water is reintroduced resurged on an international scale in the use of radiation for food preservation. In 1999, U.S. approved levels of radiation in foods are 1.5 to 3.0 kGy for poultry (fresh or frozen) and 4.5 kGy max for fresh red meat and 7.0 kGy max for frozen red meat (1 Gy 100 rad 1 kGy 1000 Gy).

Reduction of preservatives

As a result of concerns about the potential for formation of carcinogenic nitrosamines in products containing nitrite, there have been numerous studies, reports, and debates about safe levels. However, nitrite serves as a means of preventing growth of Clostridium botulinum and is thus an important safety component of these products restricting its use presents an increased risk of botulism from cured products (Marriott et al., 1981 Tompkin, 1980). The residual level of nitrite in today's cured meats is five times lower than in the 1970s (CAST, 1997), as a result in part of introducing other compounds such as ascorbates in the curing system to allow reduction of nitrites while maintaining the ability to inhibit C. botulinum (Marriott et al., 1981). Similarly, salt plays a key role in the safety of many products. Salt levels decreased considerably during the twentieth century, from levels greater than 6 in the first half of the century to around 2 today (CAST, 1997). Much emphasis has...

Scope For Future Research

The past 20 years have seen a significant increase in our understanding of the chemical, physical and biological effects of ionizing radiation on food and methodology of irradiation detection, as well as remarkable advances in industrial irradation technology, design of food irradiation plants, dosimetry, and commercial applications. Today the use ionizing energy in the processing of various food items is approved. That the irradiation treatment is a major food preservation method of great potential is quite clear. However, major research efforts are needed to find the combinations of parameters required to maximize achievement of the desired objectives while minimizing unwanted side effects, e.g., softening of certain fresh fruits and vegetables, discoloration, off-flavors. Combinations of irradiation with heat treatment or with the addition of certain additives, e.g antioxidants, should be explored further.

Increasing Energy Costs

Increasing energy costs associated with traditional methods of food preservation storage, such as freezing, has resulted in the growth of less energy-intensive and more economical methods of short- and long-term preservation, such MAP. It has been estimated that MAP is 18 to 20 less energy intensive compared to freezing for shelf-life extension of bakery products. Thermal processing to achieve ambient temperature shelf stability is energy intensive, but not nearly as much as freezing, which requires removal of heat of fusion as well as temperature reduction and maintenance of low temperature. Further, it has been demonstrated repeatedly that the 0 F (- 18 C) traditionally employed for frozen storage is well above the optimum temperature. Frozen foods are best stored at below their glass transition temperatures, a more costly and energy-intensive process being overtly resisted by commercial frozen food-distribution interests. These groups have failed to recognize the quality and hence...

Influence of emerging technologies and potential negative impacts

In addition to new physical processing technologies, manufacturers are exploring novel food preservation systems, including the use of natural preservatives such as bacteriocins, competitive microflora, lysozyme, chitinases, lactoferrin, and lactoperoxidase, to name a few. By combining physical processes with these novel food processing systems, it may be possible to design processes for the precision destruction (or inhibition) of pathogenic and or spoilage organisms, yet allow the desired fresh-like characteristics of the food to remain.

Impact of injury and stress

Archer (1996) stated that traditional food preservation systems work well to inhibit the growth of toxin-producing bacteria such as S. aureus or C. botulinum that require relatively high numbers for the toxin to cause disease. However, he expressed concern that infectious bacteria such as E. coli 0157 H7 and strains of Salmonella may increase in virulence during stressful conditions of food preservation. Stresses such as starvation and extremes of temperature, pH, and osmolarity cause adaptive responses, one of which may be to potentiate expression of virulence genes or, even worse, create unpredictable mutations in the virulence genes. To date there is little evidence that this occurs in food production, but it warrants vigilance.

Impact of technologies that reduce competitive microflora

An example of a new food preservation technology that presents a potential concern is the use of vacuum packaging and modified atmosphere packaging of foods to extend shelf-life. This would seem to be a very useful technology for packaging fresh fish, which is highly perishable. Greater shelf-life could increase consumption of what has become recognized as a very healthy food. However, a natural concern would be to question whether this technology would create conditions that would allow neurotoxin to be produced by non-proteolytic C. botulinum sooner than in fish stored in non-oxygen-reduced environments. In one study, not only was neurotoxin produced faster in modified atmospheres, it was produced before the fish was considered spoiled (Post et al., 1985). Therefore, a technology that provides a longer shelf-life for this very perishable food may suppress the natural warning system for consumers by suppressing the growth of the natural spoilage microorganisms.

Color of Fresh and Processed Poultry Meat

The basic color differences between muscles are a result of the relative amounts of white and red muscle fibers. These fibers have different characteristics, and the most noticeable difference to the consumer is their color. Meat color is largely dependent on the amount of meat pigment-myoglobin present in these fibers. Chicken breast muscle is predominantly composed of white fibers, which have a low level and therefore their color is light. On the other hand, thigh meat is mainly composed of red fibers and shows a darker color. Different poultry species also vary in the inherited amount of pigment in their muscles (chicken vs duck). The myoglobin is a complex molecule consisting of two major parts the protein portion (called globin) and the nonprotein portion (called heme). The latter is capable of binding different compounds and, by that, changing the color of the meat. When the myoglobin is bound to oxygen, chicken leg meat will appear bright pink (Fig. 2). When the same fresh meat...

Frankfurters and Bologna

Frankfurters and bologna are examples of finely comminuted meat products where the final product has a very homogeneous appearance. Dark muscle chunks and or mechanically deboned meat are usually emulsified with the fat. A bowl chopper or an emulsion mill are used to achieve an efficient particle size reduction. Salt is added to extract the meat proteins, which is essential in binding the small meat particles and stabilizing the small fat globules within the protein matrix (10). Nitrite is added to inhibit Clostridium botulinum growth and to provide the typical cured meat color (Fig. 2). The meat batter is then stuffed into cellulose casings and smoked and cooked in a smokehouse. Since frankfurters are such a high volume item, some processors have dedicated an entire continuous line for this product. As with other meat products, low microbial contamination and refrigerated temperature can help prolong the shelf life (Fig. 3).

Byproducts of irradiation

As with all preservation or cooking methods, some chemical changes occur in irradiated food. When high-energy particles strike matter, electrons are lost from atoms and ions are formed. Newly formed radiolytic products may then interact to create new compounds in the food that were not present before treatment, a few of which could produce off-flavors. In meat, this can be partly controlled by maintaining low product temperatures during the irradiation process. The most common chemical reaction during food irradiation is the conversion of water to hydrogen peroxide. Reactions such as these occur in all types of food preservation, and the few reactions unique to irradiation are not harmful.

The Impact of Refrigeration on Salt Intakes

Salt intake varies widely across the world. Some agricultural communities, e.g., the Yanomano Indians from Brazil and the Chimbus of New Guinea, do not consume salt other than that found in natural food sources. The Kamtschadales and the Tungouses nomadic tribes from the north of Russia and Siberia are also averse to added salt, whereas the Japanese have traditionally consumed large quantities of salt in pickled salted fish and vegetables. Without some form of food preservation it would be impossible to supply urban populations with food in any systematic way. Refrigerators were introduced on a mass scale from the 1960s onwards and this was accompanied by a fall in salt consumption in most countries (Table 2) refrigeration has taken over from salting as a method of preserving food. In Japan, intakes as high as the 60-g intake of a farmer recorded in 1955 and the average of 27-30 gday-1 had fallen dramatically to 8-15 g day1 by 1988. In the US, salt intake probably started to decline...

Gastric Cancer and Stroke

There is a strong geographical correlation between stomach cancer and stroke mortality, both of which correlate with salt intake. There are four recognized major etiological factors for gastric adenocarci-noma infection with Helicobacter pylori, excessive salt consumption, and low intakes of ascorbic acid, carotenoids or more generically of vegetables and fruits. Sodium chloride induces atrophic gastritis and enhances the mutagenic effect of nitrosated foods. Salt may also play a role in the later steps involving the transformation of mucosal dysplasia to carcinoma. The salted pickles and salted fish of Japanese cultures appear to be strongly linked to the development of stomach cancers.

Assessment of Total Discretionary Salt

Figure 2 compares the traditional and lithium marker techniques for assessing both total salt intake and the distribution of its sources. When table and cooking salt are combined to form a single value, the percentage contribution of these discretionary sources to the total intake measured by the lithium marker technique is significantly lower in the UK compared with that assessed by traditional methods, which do not consider salt losses during cooking and at the table. This intake in the UK seemed unusually low, but when discretionary sources (table and cooking salt) were assessed in various regions of Italy using the lithium marker technique, discretionary salt intake varied between 31 and 41 of total intake. In rural Benin the use of discretionary sources in women was higher (52 ) and in rural Guatemala was as much as 77 of total intake. Thus, the more industrialized the food system the greater the proportion of nondiscretionary salt intake, which then makes it more difficult for...

General References

Cassens, Use of Sodium Nitrite in Cured Meats Today, Food Technol. 49, 72-79, 115-116 (1995). C. N. Mendoza et al., Level and Occurrence of AT-Nitrosodimeth-ylamine, AT-Nitrosodiethylamine and AT-Nitrosopyrrolidine in Cured Meat Products, Alimentos 18, 15-19 (1993).

Scientific Basis And Implications

The majority of the pathogens that contaminate food products are natural inhabitants of the environment, soil, plants, and animals. Their survival and growth in foods is affected by a wide range of factors, which have been categorized as intrinsic and extrinsic. Application of combined or synergistic effects of these intrinsic and extrinsic factors in food preservation is the basis of barrier or hurdle technology. Pathogen growth and survival are also affected by the relationships among the varied types of microorganisms that make up the complex microbial flora. Depending on environmental conditions, these microorganisms may grow either competitively or cooperatively.

Nitrates nitrites and nitrosamines

Nitrates and nitrites in preserved meats (bacon, cold cuts) can prevent growth of Clostridium botulinum, the organism that can produce the potent botulinum toxin. However, nitrates and nitrites have been shown to have adverse effects, such as methemoglobinemia and carcinogenesis, the latter resulting from the formation of nitrosamines. Coincidentally, reduction of nitrate to nitrite is a common reaction for bacteria in the GI tract. Usually, the GI effect on nitrite is preceded by nitrate being reduced to nitrite by microflora of mouth saliva. The minimum nitrate intake for a person is estimated at 75 mg d. The resulting nitrite can oxidize hemoglobin to methemoglobin, which results in the loss of oxygen-binding ability. Consequently, dietary or water sources of nitrate and nitrite can have life-threatening effects (methemoglobinemia), particularly in young children. NADH reductase is the major enzyme responsible for the reduction of methemoglobin. Because of a transient deficiency of...

The microbial spoilage of food

Some foodstuffs are more susceptible to spoilage than others fresh items such as meat, fish, dairy produce and fruit and vegetables are all highly perishable. Foods such as rice and flour, on the other hand, are much more resistant, because having no water content they do not provide suitable conditions for microbial growth. Drying is one of a number of methods of food preservation, all designed to prevent growth of microorganisms by making conditions unfavourable. Other methods include heating canning, drying, pickling, smoking and, in many countries, irradiation.

Technological Procedures Related To Shelf Life

Table 10.7 shows the traditional methodologies that have been used by humans in order to extend the shelf life of foods and their basic preservation principles.2125-127 Freezing, canning, and drying are the three principal food preservation techniques used nowadays. The baking of bread, manufacture of ice cream, production of fruit jams, fermentation of yogurt, smoking of sausage, and many other processes result in foods with prolonged shelf life. These techniques, however, are more properly classified as manufacturing since their principal goal is the creation of a new food product. Freezing, drying, and canning are used to protect all foods (raw agricultural produce as well as manufactured food items) from microbial, chemical, or physical spoilage for many months.125

Effect Of Processing Treatments On Oxidation

Meat preservation by means of curing is typically obtained by application of mixtures containing nitrite as the key ingredient. Other ingredients in the curing mixture include sodium chloride, sugars, ascorbate, polyphosphates, and spices. Nitrite imparts multiple functional roles to cured products, inhibiting spore germination of Clostridium botulinum when added in combination with sodium chloride, producing the characteristic cured meat color, contributing to the characteristic cured meat flavor, and inhibiting the development of warmed-over flavor in cooked cured meats. Mechanisms proposed for the antioxidative activity of nitrite include formation of a strong complex with heme pigments (thereby preventing the release of nonheme iron and its subsequent catalysis of lipid oxidation), complexation of nonheme iron (which is catalytically less active than noncomplexed iron), and reaction with membrane-un-saturated lipids (which stabilizes the lipids) 301-303 . multicomponent...

Food Engineering Directorate

The Technology Acquisition Division (TAD) is structured and staffed to conduct basic research and exploratory development involving new technologies for food preservation and processing, and for foodservice equipment and operations. The TAD's function is to explore, assess, adapt and refine new materials, equipment and operational concepts as basis for establishing new technological opportunities for exploitation to meet near- and long-term military feeding requirements. As with all FED Divisions, the emphasis on R& D conducted by TAD is on military-unique requirements, for which there are no civilian counterparts.

Sterilization Versus Pasteurization

Thermal processing covers the broad area of food preservation technology in which heat treatments are used to inactivate microorganisms to accomplish either commercial sterilization or pasteurization. Sterilization processes are used with canning to preserve the safety and wholesomeness of ready-to-eat foods over long terms of extended storage at normal room temperature (nonrefrigerated) without additives or preservatives, and pasteurization processes are used to extend the refrigerated storage life of fresh foods. Although both processes make use of heat treatments for the purpose of inactivating microorganisms, they differ widely with respect to the classification or type of microorganisms targeted, and thus the range of temperatures that must be used and the type of equipment systems capable of achieving such temperatures.

Poultry Marine and Milk Products

Fish meals are produced from fish caught specifically for making meals or from the residues remaining after processing fish mostly for human consumption. Dried fish solubles are by-products of the canning and oil-production industries. After centrifuging to remove the oil, the remaining fraction can be dried to make the product. Dried skim milk and dried whey have been used for young animals. Most of the fat and fat-soluble vitamins are removed in the skim milk, and whey is the part of milk that

Packaging Part Ivcontrolled Modified Atmospherevacuum Food Packaging

The shelf life of foods such as fresh and processed meat, eggs, fish, poultry, fresh fruits, fresh vegetables, and soft bakery goods is limited in the presence of atmospheric oxygen due to three important factors the biochemical effect of atmospheric oxygen, the activity of oxidative enzymes, and the growth of aerobic spoilage microorganisms. A fourth factor of no small importance is attack by insects. Each of these factors, alone or in conjunction with one another, can result in changes in color, flavor, odor, and overall deterioration in food quality, and the hazard of microbiological safety. Technologies employed by food processors to retard these deteriorative changes include chilled storage, freezing, thermal processing, water removal, osmotic adjustment, pH change, and the use of chemical additives and preservatives. However, increasing energy costs associated with freezing and drying, quality changes imposed by the processes themselves, and growing consumer concerns about...

Thermal Sterilization Of Canned Liquid Foods

Perhaps least recognizable, however, is the important role that thermal processing technology has played in the pharmaceutical and health care industry. Large quantities and varieties of sterile solutions are required daily for surgical and patient care procedures. Sterile saline solutions, irrigation solutions, intravenous solutions with dextrose or glucose, and dialysate solutions, along with a host of other large-volume parenteral solutions in glass, plastic, flexible and semirigid containers, are sterilized in retort systems using the technology of canning for food preservation. Such products, of course, are neither thought of nor considered to be canned foods, but they are in fact a very important use of thermal processing technology throughout the world.

Thermal Processing Of Food

Thermal processing of canned foods has been one of the most widely used methods of food preservation during this century. In its broadest sense, it refers to the technology of using heat sterilization to preserve ready-to-eat foods and other biological products so that they can remain safe and wholesome under long-term extended storage at room temperature without chemical additives or preservatives. Foods preserved in this manner have become so commonplace in the human diet that the health of the world population now depends in great measure on the safety and wholesomeness of these foods. Thermal processing consists of heating food containers in pressurized retorts at specified temperatures for prescribed lengths of time. These process times are calculated on the basis of achieving sufficient bacterial inactivation (lethality) in each container to comply with public health standards and to ensure that the probability of spoilage will be less than some minimum. Associated with each...

The Concept Of Food Irradiation Has A Long History

The concept of using ionizing energy to process food has a long history. Soon after the discovery of roentgen rays in 1895, a number of visionaries suggested that this new form of energy could be of benefit to food preservation. Indeed, one of the first patents based on this idea dates back to the early years of this century (1). However, as history subsequently showed, practical limitations precluded early industrial and commercial development and application of these concepts. It is only much more recently that progress has advanced to the stage where significant industrial utilization of food irradiation is becoming widespread. This follows several decades of research and development, in government, university, military, and industrial laboratories around the world, which put in place the technical and scientific foundation for the safe and effective utilization of radiation for the processing of food.

Snack Foods from Eggs

A number of egg-rich snack foods have been proposed but, thus far, none have become significant users of eggs. A breaded, fried egg white ring that looks much like an onion ring was patented (21), and a procedure for producing an egg jerky flavored to taste like dried meat jerky was suggested (22). A cookie formulation was prepared so that each cookie contained one egg equivalent. Another snack food that is quite common is yogurt. It is possible to make a yogurt-type product using egg albumen as a partial replacement for the milk. In a sensory comparison of normal yogurt and the egg-substituted product, the latter was judged superior for mouth-feel and smoothness.

Refrigeration History

The early development of mechanical refrigeration was targeted to medical needs rather than to food preservation. John Gorrie developed a mechanical system, using air compression and expansion and the Joule-Thomson effect, to In 1923, Clarence Birdseye created the first modern frozen food business, which set in motion a revolution in food preservation that has had significant consequences to the American diet. By 1930, the list of frozen foods consisted mainly of fish, small fruits, poultry, meat, eggs, and a few vegetables. Quality was variable. Joslyn and Cruess recognized the role of enzymes in quality degradation and introduced the blanching process for the destruction of enzymes. This led to significant quality improvement. During the past 60 years, the research efforts of frozen food processors, packaging manufacturers, and university and government scientists have led to further improvements in the quality and stability of frozen foods.

Production of Vinegar

Vinegar is literally a result of souring (aigre) of wine (vin). The origin of vinegar no doubt followed the production of wine, because a bad batch of wine will result in some form of vinegar. Vinegar has been used as a flavoring agent, food preservation agent, and even as medicine. Both Eastern and Western cultures have records of vinegar in ancient history. Although vinegar production is always treated as a part of food fermentation, it is, in reality, an oxidative process. In the presence of molecular oxygen and Aceto-bacter aceti, or related species, alcohol is oxidized to acetic acid. Historically vinegar was made by the let-alone process or the field process poor quality wine was allowed to sit in the open air for oxidation to occur. Currently the methods to make vinegar are the trickling process and the

Characteristics of patients with food intolerance

Subjects reported reactions to the common allergenic foods - legumes, tree nuts, crustaceans and fish. Twenty-one out of the 22 subjects in this group had positive skin prick tests to the offending food. The second group reported reactions to food such as sugar, wheat, egg, cured meat and yeasts. Only four out of the 23 subjects in group 2 had a positive skin prick test in this group (evidence of IgE) that supported their reported reactions (chi-squared 24.68, p value < 0.0001). The second group's symptoms started at an older age - 28.9 years versus 17.1 years (p 0.0015) - and were related to a much broader range of foods - 25.6 versus an average of 5.5 (p 0.0002).

Relevance of phenolic antioxidants for functional food and comparative metabolic biology considerations

Sources have a history of use in food preservation, however, many increasingly have therapeutic and disease prevention applications (69-72). Therefore, understanding the nutritional and the disease protective role of dietary phytochemicals and particularly phenolic antioxidants is an important scientific agenda well into the foreseeable future (73). This disease protective role pf phytochemicals is becoming more significant at a time when the importance of in the prevention of oxidation linked chronic diseases is gaining rapid recognition globally. Therefore, disease prevention and management through the diet can be considered an effective tool to improve health and reduce the increasing health care costs for these oxidation linked chronic diseases, especially in low income countries.

Dietary Exposure To Nnitroso Compounds

The dietary exposure to NDMA (the most commonly occurring VNA in the diet) has been calculated in a number of food surveys and is summarized in Table 1. It should be taken into consideration that exposure estimates of this kind suffer from uncertainties in food consumption trends averaged over a population. Over the last decade, reductions in the use of nitrates and nitrites used for curing meats to the minimum amount required to inhibit bacterial growth, and modification of malting techniques in the brewing industry have resulted in significant reductions in the levels of NDMA. In most dietary surveys, cured meats and beer have been implicated as the major dietary sources of NDMA. As a direct consequence, NDMA exposure over the last decade has probably decreased from about 1 jug d to ca 0.3 fig d NDMA in most Western countries. An exposure estimate of between 10-100 fig d for currently identified NVNA would not seem unreasonable. In developing countries, particularly China and other...

Cost Reduction Methods

As indicated by Turner (2000), inexpensive biological receptors is a critical issue in the high development costs of biosensors. There is a lack of suitable biological recognition molecules that are inexpensive to manufacture and also stable during storage. Turner further indicates that this problem is exacerbated when one is manufacturing high-density arrays to be used in medical diagnostics, functional genomics, proteomics, environmental monitoring, food preservation and safety, etc.

Total Lipid Recovery

The Bligh and Dyer system can yield more lipid than most other methods, and Table 3.1 compares the recovery of lipid by three methods in the difficult case of oxidizing fishmeal, which is in essence cooked and dried fish muscle (de Koning and Mol, 1989). Food applications of solvent systems are reviewed by Sheppard et al. (1974), Hubbard et al. (1977), and Sahasrabudhe and Smallbone (1983). Particular cases, such as recovery of all the free fatty acids formed in frozen stored fish, may require modification of standard techniques such as the Bligh and Dyer chloroform-methanol system (Hardy et al., 1979). Incomplete lipid recovery is sometimes not a problem if the material recovered is a representative sample but can be misleading if food fatty acid composition data are needed. Fish phospholipids include substantial proportions of polyunsaturated fatty acids (Table 3.2), and in lean fish samples, failure to recover phospholipids can give low values of 20 5n-3 and 22 6n-3. In red meat,...

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