富含大豆异黄酮的大豆蛋白功能特性研究

Functional Properties of Soy Protein Enriched with Soybean Isoflavones

摘要:

本文研究了不同加热条件制备和表征富含异黄酮的大豆蛋白及其功能性，该蛋白极大改善了异黄酮的难溶性。选择了在pH 6.4和pH 7.0加热制备了富含纯天然大豆异黄酮（SPIG）和苷元型异黄酮（SPIA）的大豆蛋白。与大豆分离蛋白（SPI）相比，加热的SPI (HSPI)、SPIG和SPIA的发泡能力提高，pH 7.0条件下的SPIG的发泡能力为165.77±2.90%，强于其它几种条件下添加异黄酮的蛋白。同SPI相比，加入异黄酮后大豆蛋白的持水能力下降，其中SPIA6.4的持水能力最低。采用SPI、大豆蛋白与纯天然大豆异黄酮的混合物及与苷元异黄酮的混合物(MixG和MixA)、HSPI及SPIG、SPIA分别制备了乳液。SPI制备的乳液的d43为1.35±0.12 μm，MixG和MixA制备的乳液的d43为25.41±1.32 μm和24.57±1.73 μm，SPIG、SPIA制备乳液的d43为38.99±0.89 μm和34.50±0.48 μm。离心条件下的SPIG和SPIA制备的乳液的稳定系数相对降低，但该乳液同SPI制备的乳液相比具有更加良好的塑性，激光共聚焦显微镜（CLSM）的结果与d43结论相一致。

Abstract:

Soy protein enriched with isoflavones was prepared under different heating conditions and its functional characteristics were studied. The insolubility of isoflavones in protein was greatly changed. Soy protein enriched with natural soybean isoflavones (SPIG) and aglycone isoflavones (SPIA) prepared under pH 6.4 and pH 7.0 were selected. Compared with soybean protein isolate (SPI), the foaming abilities of the heated SPI (HSPI), SPIG and SPIA were enhanced after isoflavone was added. When the pH value was 7.0, the foaming ability of SPIG was 165.77 ± 2.90 %, which was stronger than that of the other proteins enriched with isoflavones. However, water holding ability of the soybean proteins decreased after adding isoflavone, and SPIA 6.4 demonstrated the lowest water holding ability. Then, SPI, the mix of soy protein and natural soybean isoflavones and aglycone isoflavones (MixG and MixA), SPIG and SPIA were respectively adopted to make emulsion. The d43 of fresh emulsion was determined; the average droplet size of SPI was 1.35 ± 0.12 μm, while the average droplet size of MixG and MixA was 25.41 ± 1.32 and 24.57 ± 1.73 μm, respectively. After heating, the average droplet size of SPIG and SPIA increased to 38.99 ± 0.89 μm and 34.50 ± 0.48 μm, respectively. The emulsion stability coefficients of SPIG and SPIA under centrifugal condition were relatively low, but the emulsion had better plasticity than the emulsion of SPI. The conclusion derived?from confocal laser scanning photomicrographs (CLSM) was corresponded with d43.