Structure-modifying alkaline and acidic pH-shifting processes promote film formation of soy proteins |
| |
Authors: | Jiang Jiang Youling L Xiong Melissa C Newman Gregg K Rentfrow |
| |
Affiliation: | 1. State Key Laboratory of Food Science and Technology, and School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China;2. Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40546, USA |
| |
Abstract: | The effect of pH-shifting, a process that induces the molten globule state in proteins, on the film-forming potential of soy protein isolate (SPI) at different temperatures was investigated. Partial unfolding at pH 1.5 or 12, followed by refolding at pH 7.0, was performed to alter the protein structure. Glycerin-plasticised films were prepared from pH-treated SPI at ambient temperature (20 °C), or by heating at 50, 60, 70, or 80 °C (30 min). Tensile strength (TS), elongation at break (EAB), water vapour permeability (WVP), protein solubility (pH 3–7), and non-participating proteins of films were analysed, and the film microstructures were examined. The pH12-treated SPI spontaneously formed a transparent, slightly yellowish film at 20 °C, which had the greatest EAB, while pH1.5-treated and native SPIs required preheating at 50 and 70 °C, respectively, to form a film. Heating generally decreased solubility and WVP but increased TS. Films formed from both pH12- and pH1.5-treated SPIs were more elastic (up to 2-fold greater in EAB, P < 0.05) than the film formed from untreated SPI despite slightly reduced TS and WVP. Electrophoresis revealed disulphide bonds between A and B subunits of glycinin being a dominant force in pH12- and pH1.5-treated SPI films, while noncovalent forces were abundant in untreated SPI films. The pH12-treated SPI film consisted of more interactive protein strands than other SPI films, which seemed to explain its superior elastic properties. |
| |
Keywords: | Edible film Soy protein pH-shifting Microstructure |
本文献已被 ScienceDirect 等数据库收录! |
|