Freezing, dehydration

Chemical analyses and fractionations. Freeze-dehydrated cotton tissue was analyzed for condensed tannin (heated n-BuOH-HCl), gossypol (phlorogluclnol-HCl), and anthocyanlns-anthocyanldlns (ale. HCl at 540 nm). Other analyses performed but not reported here were for catechin, total phenols, (tannin), and aniline reactive terpenes (gossypol). 

Layer-by-layer electrostatic deposition of biopolymers at interface of emulsion droplets Polyelectrolyte capsules microparticles with novel functionality and triggered release multiple layers around oil droplets exhibiting improved stability towards environmental stresses (temperature, ionic strength, pH, freezing, dehydration) McClements, 2005, 2006 Sanguansri and Augustin, 2006... 

Figure 7.27. Location of various food processes, ineluding freezing, dehydration, heating and cooling, on a state diagram (Reproduced with permission from Effeets of glass transition on processing and storage by Karel, Buera, and Roos (In The Glassy State in Foods, Blanshard and Lillford (Eds.)), 1993, Nottingham University Press.)...

Figure 4. Influence of freezing (—20°C) and freeze-dehydration of prerigor muscle tissue on the activities of aconitase and fumarase in the muscle press juice. Percent of the total extractable activity. The press juice was prepared from the thawed tissue and the rehydrated tissue...

Table VI. Influence of Freezing and Freeze-Dehydration of Bovine Longissimus Muscle (Postrigor) on GOT and GOTm in the Muscle-Press Juice6 (26)...

Jones, S. B. (1977). Ultrastructure characteristics of beef muscle. Food Technol. 31(4), 82. Judge, M. D., Okos, M. R., Baker, T. G., Potthast, K., and Hamm, R. (1981). Energy requirements and processing costs for freeze-dehydration of prerigor meat. Food Technol. 35(4), 61. 

As the temperature of the product increases, the reaction rate constant is increased (Equation 24.53). The dependence of reaction constant on temperature implies that low-temperature dehydration would produce products with less nutrient disintegration. The vacuum and freeze dehydration processes thus would result in less nutrient degradation compared with other drying processes. A longer constant rate drying period also increases nutrient retention because, owing to evaporative cooling, product is at rather lower temperatures. 

Karmas, E., J.E. Thompson, and D.B. Peryam. Thiamin retention in freeze-dehydrated irradiated pork. Food Technol. 16 107-108,1962. 

J. Hawkes and J.M. Fhnk, Osmotic concentration of fruit slices prior to freeze dehydration, J. Food Pwc. Pres., 2 265 (1978). 

Canning and freezing result in considerable losses of vitamin B-6 with the losses being smaller in frozen foods. Freeze-dehydration and subsequent storage appear to have no adverse effect on the vitamin B-6 content of meat and pouitry. 

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