Introduction

101 Toxic Food Ingredients

101 Toxic Food Ingredients

Get Instant Access

Food antimicrobials are chemical compounds added to or present in foods that retard microbial growth or kill microorganisms. The functions of food antimicrobials are to inhibit or inactivate spoilage microorganisms and pathogenic microorganisms. The latter function has increased in importance in the past 10-15 years as food processors search for more and better tools to improve food safety (Davidson, 2001). Prior to recent approvals of certain compounds to control foodborne pathogens by worldwide regulatory agencies, one of the only uses of antimicrobials to control a pathogen was nitrite or nitrate against Clostridium botulinum in cured meats.

A number of compounds are approved by international regulatory agencies for use as direct food antimicrobials (Table 2.1). The question arises as to why, with so many compounds already approved for use in foods, would the food processing industry need a greater number of food antimicrobials? The primary incentive for searching for effective antimicrobials among naturally occurring compounds is to expand the spectrum of antimicrobial activity over that of the regulatory-approved substances. Most of the traditional, currently approved food antimicrobials have limited application due to pH or food component interactions. For example, organic acids function at low concentrations only in high acid foods (generally less than pH 4.5-4.6). This is because the most effective antimicrobial form is the undissociated acid which exists in majority only at a pH below the pKa of the compound. All regulatory-approved organic acids used as antimicrobials have pKa values less than 5.0 (Table 2.2) which means their maximum activity will be in high-acid foods. For food products with a pH of 5.5 or greater, there are very few compounds that are effective at low

Table 2.1 Current regulatory-approved compounds for use as direct addition food antimicrobials

Compound or group of compounds

Alkyl esters ofp-hydroxybenzoic acid (Parabens; methyl, ethyl, propyl, butyl and heptyl)

Acetic acid and acetate salts, diacetates, dehydroacetic acid

Benzoic acid and benzoate salts

Dimethyl dicarbonate, diethyl dicarbonate

Lactic acid and lactate salts

Lysozyme

Natamycin

Nisin

Nitrites and nitrates Phosphates

Propionic acid and propionate salts Sorbic acid and sorbate salts Sulfite derivatives

Table 2.2 pKa of regulatory-approved organic acids

Compound or group of compounds

PKa

Acetic acid

4.75

Benzoic acid

4.19

Lactic acid

3.79

Propionic acid

4.87

Sorbic acid

4.75

concentrations. Another factor leading to reduced effectiveness among food antimicrobials is food component interactions. Most food antimicrobials are amphiphilic. As such, they can solubilize in or be bound by lipids or hydrophobic proteins in foods making them less available to inhibit microorganisms in the food product.

Interest in natural antimicrobials is also driven by the fact that international regulatory agencies are generally very strict about requirements for toxicological evaluation of novel direct food antimicrobials. In many parts of the world, toxicological testing of new synthetic compounds could take many years and many millions of dollars to obtain approval. For some types of food additives a payback may be possible (e.g., artificial sweeteners), but for food antimicrobials it is less likely that obtaining approval would be profitable.

An argument often used to justify natural antimicrobials is that they will produce 'green' labels, i.e., one with few or no 'synthetic' additives in the ingredient list. While this rationale may be true, it must be remembered that many of the antimicrobial compounds approved for use in foods today come from natural sources (Table 2.3). If a truly effective antimicrobial was discovered from a natural source, it may be more economically feasible to synthesize it than to extract it from a natural source. This justification also leads

Table 2.3 Natural sources for antimicrobials

Compound or group of compounds

Natural source

Acetic acid

Vinegar

Benzoic acid

Cranberries, plums, prunes, cinnamon,

cloves, and most berries

Lactic acid

Lactic acid bacteria

Propionic acid

Swiss cheese (Propionibacterium

freudenreichii ssp. shermanii)

Sorbic acid

Rowanberries

consumers to the mistaken belief that food additives currently in use are potentially toxic and should be avoided.

In addition to potential benefits associated with natural antimicrobials in foods, there are a number of potential concerns that need to be examined with respect to food safety. For example, if an antimicrobial is to be used exclusively to inhibit a pathogenic microorganism, it must be uniformly effective, stable to storage, and stable to any processes to which it is exposed. Standardized assays for activity need to be developed to ensure that the antimicrobial compounds retain potency. Finally, producers and users of natural antimicrobials that make claims for efficacy of use will be likely to be liable for any claims they make. In short, natural antimicrobials have excellent potential but probably will not produce miracles.

Was this article helpful?

0 0
Vegetarian Food and Cooking

Vegetarian Food and Cooking

Switch To A Vegetarian Diet And Live To Be A 100. Are You Suffering From Weak Bones And Digestive Disorders? Did You Ever Wonder About Why You Feel Restless, Listless Or Anxious Without Any Plausible Reason? The Answer Probably Lies In Your Dietary Habits.

Get My Free Ebook


Post a comment