Frozen food temperature decrease

Upon further storage, the concentration in the outer layer decreases until it reaches the equilibrium concentration. The duration of this decrease depends on the DF value and this can decrease rapidly with decreasing temperature. Because of this it is possible to get a concentration of odor compounds in a thin external layer of frozen foods. 

It has been proposed that the absorption of ultrasound energy depends on the thermo-elastic relaxation of ice crystals in food and is affected by ice crystal orientation and size, impurities present in the ice crystals, as well as temperature (Kissam et al., 1981). Miles and Shore (1978) and Shore et al. (1986) found that ultrasound was more attenuated in frozen meats than in unfrozen tissues and that the attenuation increased markedly with temperature, reaching the maximum near the initial freezing points of the foods before decreasing rapidly at higher temperatures, thus making ultrasound particularly suitable for the controlled thawing of foods (Miles et al., 1999 Torley and Bhandari, 2007). 

Applications such as thin-wall injection molded containers require processability for easier flow and faster cycle times, and impact strength for durability and crack resistance—especially at low temperatures for refrigerated and frozen food applications. Yet for typical HDPE injection molding resins, when the processing index is decreased for improved mold flow and extrudability, dart impact also decreases. 

Along the line AB, solid is in equilibrium with vapor. If the pressure is decreased below the line AB, the solid will sublime. This relationship is the basis of freeze-drying foods, such as those shown in Figure 25. The food is frozen, and then a vacuum is applied. Water sublimes, which dehydrates the food very quickly. The food breaks down less when water is removed at the low temperature than when water evaporates at normal temperatures. 

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