Food materials changes

Environmental agents that influence microsomal reactions will influence hexachloroethane toxicity. The production of tetrachloroethene as a metabolite is increased by agents like phenobarbital that induce certain cytochrome P-450 isozymes (Nastainczyk et al. 1982a Thompson et al. 1984). Exposure to food material or other xenobiotics that influence the availability of mixed function oxidase enzymes and/or cofactors will change the reaction rate and end products of hexachloroethane metabolism and thus influence its toxicity. 

Using the time-dependent aspect of state diagrams, Roos (2003) illustrated the effects of temperature, water activity, or water content on relaxation times and relative rates of mechanical changes in amorphous systems (Figure 36). This diagram can be considered as a type of mobility map, where mobility increases (relaxation time decreases) as temperature and/or water content/activity increases. Le Meste et al. (2002) suggested the establishment of mobility maps for food materials showing characteristic relaxation times for different types of molecular motions as a function of temperature and water content. 

The main unique feature of osmotic dehydration, compared to other dehydration processes, is the penetration of solutes into the food material. Through a calculated incorporation of specific solutes into the food system, it is possible, to a certain extent, to change nutritional, functional, and sensory properties, making it more suitable to processing by... 

During the process, the solute diffuses into the intercellular space and, depending on the characteristics of the solute, it may pass through the membrane and enter the intracellular space. Differences in chemical potentials of water and solutes in the system result in fluxes of several components of the material and solution water drain and solute uptake are the two main simultaneous flows. Together with the changes in chemical composition of the food material, structural changes such as shrinkage, porosity reduction, and cell collapse take place and influence mass transfer behavior in the tissue. 

Food materials leaching into the oil, breakdown of the oil itself, and oxygen absorption at the oil -air interface contribute to change the pure triglyceride oil into a mixture of hundreds of compounds. These materials increase heat transfer and also reduce the surface tension between the... 

S. B. 1984. Characterisation of rheological changes during the processing of food materials. In Gums and Stabilisers for the Food Industry, 2 (G.O. Phillips, D.J. Wedlock, andP.A. Williams, eds.) pp. 357-366. Pergamon Press, Oxford. 

Table II gives the results of residual trypsin inhibitor levels for the various soymilk preparations. The 90 and 120 sec microwave treatments were the most effective in inactivating the trypsin inhibitor complex while hot water treated and unheated samples showed the highest levels. It is not surprising to find that microwave processing is more efficient than hot water in suppressing trypsin inhibitor considering the rapid penetration of food material by microwaves and the susceptibility of protein action to small heat induced changes in tertiary structure. Hence, Collins and McCarty (12) found microwaves produced a more rapid destruction of endogenous potato enzymes (polyphenol oxidase and peroxidase) than hot water heating.

The physical/chemical states and the thermal transitions of food materials determine the process conditions, functionality, stability and overall quality, including the texture, of the final food products. Carbohydrates and proteins— two major biopolymers in various food products—can exist in an amorphous metastable state that is sensitive to moisture and temperature changes (Cocero and Kokini 1991 Madeka and Kokini 1994, 1996). The physical states of components in a biopolymer mixture determine the transport properties, such as viscosity, density, mass and thermal dif-fusivity, together with reactivity of the material. 

Flavor Release Flavor release is the process whereby flavor molecules move out of a food and into the surrounding saliva or vapor phase during mastication (126, 127). The release of flavors from a food material occurs under extremely complex and dynamic conditions (136). A food usually spends a relatively short period (typically 1 to 30 seconds) in the mouth before being swallowed. During this period, it is diluted with saliva, experiences temperature changes, and is subjected to a variety of mechanical forces. Mastication may therefore cause dramatic changes in the structural characteristics of a food emulsion. 

Thixotropic Fluids. Thixotropic fluids are characterized by a decrease in their viscosity with time at a constant shear rate and fixed temperature. When shear rate is steadily increased from 0 to a maximum value and then immediately decreased toward 0, a hysteresis loop is formed, as shown in Figure 3. The shape of the hysteresis loop is also a function of the rate by which the shear rate, 7, is changed. Oil-well drilling muds, greases, and food materials are examples of thixotropic fluids. 

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