On Line Instrumentation

In a few cases moisture measurements have been carried out on line, or at least beside a production line. In order to build an on line system a number of special spatial and temporal considerations have to be considered (Bjorkstam and Listerud, 1985). Most of these relate to the design of the NMR magnet and the radio frequency excitation coil. The sample must pass through both components simultaneously. Both must clearly be sufficiently large to accommodate the product but an overlarge magnet...

Low Resolution Nuclear Magnetic Resonance

When a sample containing magnetic nuclei such as hydrogen protons is placed in a static magnetic field, B0, the nuclei align with the field and a bulk nuclear magnetisation develops. This process occurs exponentially in a characteristic time T1( the spin lattice relaxation time such that where M(t) is the magnetisation at time t and M0 is the equilibrium magnetisation. In almost all food systems commonly encountered Tj values are of order 1.0 s. If the magnetisation is disturbed from the...

Future Technologies And Challenges

The world energy consumption, conservation, environmental concerns, worldwide market globalization, frozen, refrigerated, shelf stable processed food products competition and the high manufacturing costs will force the frozen food products industry to increase R& D challenges and to develop new technologies. These new technologies could be based on 1. Equipment Automation. Improvement in equipment automation, by using sensors and computer control systems to increase equipment efficiency and...

Irradiation Sources And Facilities

Two types of radiation sources are used in food irradiation, radionuclide and machine radiation. Radionuclides are radioactive elements which upon decay release deeply penetrating gamma rays. Cobalt-60, produced by exposing Cobalt-59 to neutrons, and cesium-137, a by-product of nuclear reactors, are the only radionuclides permitted in food processing. However, cesium-137 is less widely used because of its limited availability. The machine sources are electron beam generators or electron...

Crystallisation And Freezing

Decrease in mobility during freezing or crystallisation greatly attenuates MR signal amplitude, providing a means of following these related processes. Intensity of the MR signal depends on the relaxation rate of the interrogated nuclei the very fast relaxation rates found in solids prevent observation by use of liquid MR techniques. This inability to observe nuclei in a solid matrix presents a method for observation of kinetics of the liquid-solid phase transition. Disappearance of signal from...

References

Ionizing Energy for Food Processing. Council for Agricultural Science and Technology. Special Publication No. 15. Anon. 1986 . CAST. Ionizing Energy in Food Processing and Pest Control. Council on Agricultural Science and Technology, Report 109. Anon. 1989 . CAST. Ionizing Energy in Food Processing and Pest Control. Council for Agricultural Science and Technology, Task Force Report No. 115. Anon. 1991a . IAEA-TECDOC-587. Analytical Detection Methods for Irradiated Foods. A...

Application To Triglyceride Crystallization

Turning at last to foods, the rates at which oils crystallize and undergo polymorphic transitions are important in determining texture and physical stability in a variety of food products Larsson, 1982 . Edible oils consist almost entirely of triglycerides, with small amounts of mono- and di-glycerides and other minor components Swern, 1979, Chapter 1 . Hence attention has been concentrated on crystallization of triglycerides TG's . Before continuing this section, it may be useful to the reader...

Syneresis

Our discussion now moves from the very slow movement of separating emulsions to the faster flow of syneresis, an earlier process in cheesemaking. Syneresis, the expulsion of whey from shrinking cheese curd, begins immediately after disturbance of the curd by cutting. Control and understanding of conditions affecting rates of syneresis would aid in the reproducible manufacture of quality cheese. Until recently, all methods for measuring syneresis involved mechanical disturbance of the curd...

Types Of Online Sensors

A new generation of sophisticated analytical sensors is beginning to allow real-time on-line information on the plant floor of food manufacturing operations. There are a number of different ways to classify and describe on-line sensors for processing systems. Sensors may be invasive or non-invasive. Due to the harshness of food processing environments, it is always desirable to use sensors that do not contact the food system. However, in many situations including some of those involved in...