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

食品和细胞冷冻中冰晶形成的机制及其与食品加工和细胞活力的关系

基本信息

批准号：
02660136
负责人：
MIYAWAKI Osato
金额：
$ 1.28万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

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.

在食品生产过程中，控制食品和活细胞中形成的冰结构对于预测和控制食品的性质是非常重要的。研究了结冰过程中冰结构与冻结条件的关系，以及结冰结构对冷冻干燥、渐进冻结浓缩和冻结质化行为的影响。研究结果表明：(1)我们提出的三步冻结模型能较好地预测随温度变化的含冰量冻结和过冷过程中的相变行为.(2)从理论和实验上描述了冻结锋的结构：(冻结前沿的移动速度)=(冻结时水的传质速率)x(冻结前沿的表面积).(3)在冷冻干燥过程中，由于形成了细小的冰晶结构，冻结速度越快干燥速度越慢.在悬浮液和溶液的渐进式冷冻浓缩中，冻结速度越快，通过冻结前沿复杂的结构，冷冻浓缩率越低。为了提高冷冻浓缩率，可以通过搅拌来提高冻结前沿的传质速率。在大豆蛋白的冷冻质构过程中，冷冻越慢，蛋白质的变性程度越高。所有这些结果都可以用(2)中描述的冻结前沿结构与冻结速度之间的理论关系来解释。(4)Bailey Alicante A的酵母和培养细胞的冻结伴随着相当程度的过冷。作为冷冻保护剂，DMSO具有两种不同的作用：降低冰点和增加不冻水含量。