State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University , 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China.
J Agric Food Chem. 2014 Nov 12;62(45):10989-97. doi: 10.1021/jf503952s. Epub 2014 Nov 3.
Phytate is an important antinutritional factor in food products. In this study, a phytase-assisted processing method was used to produce low-phytate soybean protein isolate (SPI) samples, and their physicochemical and functional properties were examined. Hydrolysis condition at low temperature (room temperature) and pH 5.0 was better than that recommended by manufacturer (pH 5.0, 55 °C) at keeping the properties of SPI, so the former condition was selected to prepare SPI samples with phytate contents of 19.86-0.11 mg/g by prolonging hydrolysis time (0 (traditional method), 5, 10, 20, 40, and 60 min). Ash content (R(2) = 0.940), solubility (R(2) = 0.983), ζ-potential value (R(2) = 0.793), denaturation temperatures (β-conglycinin, R(2) = 0.941; glycinin, R(2) = 0.977), emulsifying activity index (R(2) = 0.983), foaming capacity (R(2) = 0.955), and trypsin inhibitor activity (R(2) = 0.821) of SPI were positively correlated with phytate content, whereas protein content (R(2) = 0.876), protein recovery (R(2) = 0.781), emulsifying stability index (R(2) = 0.953), foaming stability (R(2) = 0.919), gel hardness (R(2) = 0.893), and in vitro digestibility (R(2) = 0.969) were negatively correlated with phytate content. Simulated gastrointestinal digestion and subsequent dialysis showed that percentages of dialyzable Zn and Ca were increased with decreasing phytate content, whereas the amounts of dialyzable Zn and Ca revealed different behaviors: the former was increased and the latter was decreased. Circular dichroism spectra showed that secondary structure of SPI was changed by phytase. Compared with traditional processing method, the phytase-assisted processing method could produce SPI with lower phytate and higher protein contents, which had better in vitro digestibility and could be used to prepare gels with higher hardness by partially losing some other functional properties.
植酸是食品中的一种重要抗营养因子。在本研究中，采用植酸酶辅助加工方法生产低植酸大豆分离蛋白（SPI）样品，并对其理化和功能特性进行了研究。在保持 SPI 特性方面，低温（室温）和 pH 值 5.0 的水解条件优于制造商推荐的条件（pH 值 5.0，55°C），因此选择前者通过延长水解时间（0（传统方法）、5、10、20、40 和 60 分钟）来制备植酸含量为 19.86-0.11mg/g 的 SPI 样品。灰分含量（R²=0.940）、溶解度（R²=0.983）、ζ-电位值（R²=0.793）、变性温度（β-伴大豆球蛋白，R²=0.941；大豆球蛋白，R²=0.977）、乳化活性指数（R²=0.983）、泡沫能力（R²=0.955）和胰蛋白酶抑制剂活性（R²=0.821）与植酸含量呈正相关，而蛋白质含量（R²=0.876）、蛋白质回收率（R²=0.781）、乳化稳定性指数（R²=0.953）、泡沫稳定性（R²=0.919）、凝胶硬度（R²=0.893）和体外消化率（R²=0.969）与植酸含量呈负相关。模拟胃肠道消化和随后的透析表明，可透析的 Zn 和 Ca 的百分比随着植酸含量的降低而增加，而可透析的 Zn 和 Ca 的量表现出不同的行为：前者增加，后者减少。圆二色光谱表明植酸酶改变了 SPI 的二级结构。与传统加工方法相比，植酸酶辅助加工方法可以生产出植酸含量较低、蛋白质含量较高的 SPI，具有更好的体外消化率，并且可以通过部分损失一些其他功能特性来制备硬度更高的凝胶。
