Fang Yapeng, Li Liangbin, Inoue Chiharu, Lundin Leif, Appelqvist Ingrid
Unilever Food and Health Research Institute, Olivier van Noortlaan 120, 3133AT Vlaardingen, The Netherlands.
Langmuir. 2006 Nov 7;22(23):9532-7. doi: 10.1021/la061865e.
The effects of ionic strength, temperature, and pH on the phase separation behavior of type B pigskin gelatin/sodium-type kappa-carrageenan aqueous mixtures were investigated. Depending on the different combinations of temperature and sodium chloride (NaCl) concentration, the mixtures showed compatible, associative, and segregative phase separation behaviors. Additionally, a coexistence of associative and segregative (associative-co-segregative) phase separations was expected at low temperature and low NaCl concentration. These different phase separation events were observed using confocal scanning laser microscopy. Moreover, it was found that the segregative phase separation when alone is induced by the ordering of kappa-carrageenan chains, while that in the coexistence region is induced by the ordering of gelatin chains. pH had a significant effect on the associative phase separation, resulting in morphologies changing from compatible solution to liquid coacervate and further to solid precipitate with decreasing pH. These were attributed to the dramatic changes of the charge density of amphoteric gelatin during the pH decrease.
研究了离子强度、温度和pH值对B型猪皮明胶/钠型κ-卡拉胶水性混合物相分离行为的影响。根据温度和氯化钠（NaCl）浓度的不同组合，混合物表现出相容、缔合和分离的相分离行为。此外，在低温和低NaCl浓度下，预计会同时存在缔合和分离（缔合-共分离）相分离。使用共聚焦扫描激光显微镜观察到了这些不同的相分离事件。此外，还发现单独的分离相分离是由κ-卡拉胶链的有序排列引起的，而共存区域中的分离相分离是由明胶链的有序排列引起的。pH值对缔合相分离有显著影响，随着pH值的降低，形态从相容溶液变为液体凝聚层，进而变为固体沉淀。这些归因于两性明胶在pH值降低过程中电荷密度的剧烈变化。
