Institute for Food, Nutrition and Well-being and Department of Food Science, University of Pretoria, Private Bag X 20, Hatfield 0028, South Africa.
Food Chem. 2018 Apr 15;245:178-188. doi: 10.1016/j.foodchem.2017.10.082. Epub 2017 Oct 16.
Zeins of differing sub-class composition much more readily formed visco-elastic masses in water or acetic acid solutions than equivalent kafirin preparations. Visco-elastic masses could be formed from both zein and kafirin preparations by coacervation from glacial acetic acid. Dissolving the prolamins in glacial acetic acid apparently enabled protonation and complete solvation. Stress-relaxation analysis of coacervated zein and kafirin visco-elastic masses showed they were initially soft. With storage, they became much firmer. Zein masses exhibited predominantly viscous flow properties, whereas kafirin masses were more elastic. The γ-sub-class is apparently necessary for the retention of visco-elastic mass softness with kafirin and zein, and for elastic recovery of kafirin. Generally, regardless of water or acetic acid treatment, all the zein preparations had similar FTIR spectra, with greater α-helical conformation, than the kafirin preparations which were also similar to each other. Kafirin visco-elastic masses have a much higher elastic character than zein masses.
与等量的醇溶蛋白制剂相比，不同亚类组成的玉米醇溶蛋白在水或乙酸溶液中更容易形成黏弹体。通过从冰醋酸共凝聚，可以从玉米醇溶蛋白和醇溶蛋白制剂中形成黏弹体。在冰醋酸中溶解醇溶蛋白显然可以实现质子化和完全溶解。共凝聚玉米醇溶蛋白和醇溶蛋白黏弹体的应力松弛分析表明，它们最初是柔软的。随着储存时间的延长，它们变得更加坚硬。玉米醇溶蛋白的黏弹体表现出主要的粘性流动特性，而醇溶蛋白的黏弹体则更具弹性。γ-亚类显然对于保持醇溶蛋白和玉米醇溶蛋白黏弹体的柔软性以及醇溶蛋白的弹性恢复是必要的。一般来说，无论用水还是乙酸处理，所有的玉米醇溶蛋白制剂都具有比醇溶蛋白制剂更大的α-螺旋构象，而醇溶蛋白制剂彼此之间也很相似。醇溶蛋白黏弹体具有比玉米醇溶蛋白黏弹体更高的弹性特性。
