Mechanism of the ice crystal formation in the freezing of foods and cells and its relationship to the food processing and cell viability

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Control of the ice structure formed in foods and living cells is very important for the prediction and the control of food properties in the food manufacturing process. Relationship between the ice structure and the conditions at the freezing was investigated along with the effects of the ice structure formed on the behaviors in the freeze drying, the progressive freeze concentration, and the freeze texutization. The results obtained from the present project were as follows.(1)The three step freezing model proposed by us was effective for the prediction of the phase change behavior involving the freezing of the temperature dependent ice fraction and the supercooling.(2)The structure of the freezing front was described theoretically and experimentally by the equation ; (moving speed of the freezing front)=(mass transfer rate of the water at the freezing frotit)x(surface area of the freezing front).(3)In the freeze dryinic, the faster freezing speed gave the slower drying rate because of the fine ice structure formed. In the progressive freeze concentration of suspension and solution, the faster freezing speed gave the poorer freeze concentration yield through the complex structure of the freezing front. For the improvement in the freeze concentration yield, increase in the mass transfer rate at the freezing front by agitation was erective. In the freeze texurization of soy protein, the slower freezing gave the higher extent of the protein denaturation. All of these results were generally explained by the theoretical relationship between the freezing front structure and the freezing speed described in(2).(4)Freezing of yeast and the culture cell of Bailey Alicante A was accompanied with a substantial extent of supercooling. As a cryoprotectant, DMSO had two different fucnctions : the freezing point depression and the increase in the unfreezable water content.