• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文会议>The 8th International Symposium on the Properties of Water, 8th, Sep 16-21, 2000, Zichron Yaakov, Israel >Mechanisms of Shrinkage during Dehydration
【24h】

Mechanisms of Shrinkage during Dehydration

机译：脱水过程中的收缩机理

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

This presentation reviews different mechanisms of shrinkage that have been studied by using hydrophilic polyacrylamide or hydrophobic poly N-isopropylacrylamide gels as a model system. Very gentle dehydration processes were used to prevent moisture gradients and constrained shrinkage. With regard to contraction upon water removal, food products may be viewed as being constructed of two groups of elements. The first group includes all those elements that have a negligible moisture content and thus do not change their volume in a dehydration process. Such elements consist of crystalline material (cellulose, starch granules, sugars and salts crystals), lipids, gas phase and even very highly cross-linked polymers. Shrinkage of a system of such elements will take place only by their deformation and change in their organization. The second group includes all the elements that their volume depends on their moisture content, namely solutions of polymers and of low molecular solutes as well as gel-like polymeric network. These elements contract when water is removed in the same way as any solution. Plant and animal tissue cells, containing a solution, behave in the same way as long as the cell wall follows the receding liquid front. The solution-like behaviour continues until phase separation or transition to a glassy state occurs. In a hydrophobic polymer system, a phase separation may be induced by the combine effect of the temperature and the type and concentration of the solutes present in the system. In heterogeneous food systems, percolation of rigid enough particulates may determine the end point of the macroscopic volumetric shrinkage.
机译：本演示文稿回顾了通过使用亲水性聚丙烯酰胺或疏水性聚N-异丙基丙烯酰胺凝胶作为模型系统研究的不同收缩机制。使用非常温和的脱水过程来防止水分梯度和收缩受限。关于除水时的收缩，食品可被视为由两组元素构成。第一组包括水分含量可忽略不计，因此在脱水过程中不会改变其体积的所有那些元素。这些元素由结晶物质（纤维素，淀粉颗粒，糖和盐晶体），脂质，气相甚至非常高度交联的聚合物组成。这种元件的系统的收缩仅通过它们的变形和组织的改变而发生。第二组包括其体积取决于其水分含量的所有元素，即聚合物和低分子溶质的溶液以及凝胶状聚合物网络。当以与任何溶液相同的方式除去水时，这些元素会收缩。只要细胞壁跟随液体后退，含有溶液的动植物组织细胞就会以相同的方式起作用。溶液状的行为一直持续到发生相分离或转变为玻璃态。在疏水性聚合物体系中，温度和体系中存在的溶质的类型和浓度的综合作用可引起相分离。在异质食品系统中，足够刚性的颗粒的渗滤可能决定宏观体积收缩的终点。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号