辐照辅助接枝反应提高大豆蛋白乳液冻融性质

采用辐照技术辅助大豆分离蛋白(soybean protein isolate,SPI)与麦芽糖(maltose,M)发生接枝反应,进而改善SPI乳液的冻融性质,研究SPI质量分数、m(SPI)∶m(M)、辐照剂量对改性产物的接枝度、褐变程度和乳析指数的影响。结果表明,在SPI质量分数4%、m(SPI)∶m(M)为4∶1和辐照剂量7.5 kGy的条件下,经历1、2、3次冻融循环后,与SPI相比,改性SPI乳析指数分别降低了23.58%、29.9%和31.2%。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果证实SPI与麦芽糖发生接枝反应。改性SPI乳液经过冻融循环的出油率与SPI相比得到明显改善。光学显微镜观察结果也证实优化后的SPI微观结构更稳定。研究表明辐照能够辅助接枝反应,提高大豆蛋白乳液冻融性质,为综合改性技术提供新思路。

Improving Freeze-Thaw Stability of Soybean Protein Emulsion by Irradiation-Assisted Grafting Reaction

Irradiation technology was used to assist the grafting reaction between soybean protein isolate(SPI)and maltose(M)to improve the freeze-thaw stability of SPI emulsion.The effects of SPI concentration,m(SPI)/m(M)ratio,and irradiation dose on the grafting degree,browning degree and creaming index of modified products were studied.It was found that under the conditions:SPI concentration of 4%,m(SPI)/m(M)ratio of 4:1 and radiation dose of 7.5 kGy,the creaming index of modified SPI was decreased by 23.58%,29.9%and 31.2%,respectively,after 1,2 and 3 freeze-thaw cycles when compared with intact SPI.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)confirmed the grafting reaction between SPI and maltose.The oil release rate of the modified SPI emulsion after freezing and thawing was significantly improved when compared with SPI emulsion.Optical microscopy observation also confirmed that the optimized SPI microstructure was more stable.This study suggested that irradiation could enhance the grafting reaction to improve the freeze-thaw stability of SPI emulsion,which will provide a new integrative protein modification approach.