利用魔芋葡甘聚糖与大豆分离蛋白(soybean protein isolate,SPI)发生美拉德反应可改性SPI,但魔芋葡甘聚糖的氧化度对该反应及其产物性质的影响还未清楚.因此,该研究首先制备不同氧化度的氧化魔芋葡甘聚糖(oxidized konjac glucomannan,OKGM),再通过美拉德反应与SPI制备相应产物(SPI-OKGM),探究OKGM氧化度(26.80%、42.98%和59.66%)、SPI与OKGM质量比(1∶4~4∶1)对SPI-OKGM结构和功能特性的影响.结果表明,SPI-OKGM 26.80、SPI-OKGM 42.98和SPI-OKGM 59.66的美拉德反应程度分别在SPI与OKGM质量比为1∶2、1∶1和1∶1时较高,其中接枝度分别为35.15%、38.38%和40.62%,褐变强度分别为0.27、0.42和0.46;SPI-OKGM 的理化性能较SPI和SPI+OKGM共混物显著提高,其中SPI-OKGM 26.80、SPI-OKGM 42.98和SPI-OKGM 59.66的乳化活性分别提高63.32%、65.37%和70.50%,乳化稳定性分别提高23.08、27.52、27.26 min,抗脂质氧化能力分别提高了 26.56%、28.96%和23.34%.扫描电镜结果表明SPI-OKGM呈现出松散的薄片状,蛋白质聚集程度降低.该研究结果可为改善KGM功能性质并拓展OKGM在美拉德反应改性蛋白等方面的应用提供一定借鉴.
Soybean protein isolate(SPI)can be modified by the Maillard reaction between konjac glucomannan and SPI,but the effect of the oxidation degree of konjac glucomannan on the reaction and the properties of the Maillard reaction products(SPI-OKGM)is not clear.Therefore,in this study,oxidized konjac glucomannan(OKGM)with different degrees of oxidation was prepared,and then the SPI-OKGM were prepared by the Maillard reaction of SPI and OKGM.The effects of the oxidation degree of OKGM(26.80%,42.98%,and 59.66%)and the mass ratio of SPI to OKGM(1∶4-4∶1)on the structural and functional properties of SPI-OKGM were investigated.Results showed that the degree of Maillard reaction of SPI-OKGM 26.80,SPI-OKGM 42.98,and SPI-OKGM 59.66 was higher when the mass ratios of SPI to OKGM were 1∶2,1∶1,and 1∶1,respectively.The grafting degree was 35.15%for SPI-OKGM 26.80,38.38%for SPI-OKGM 42.98,and 40.62%for SPI-OKGM 59.66 and the corresponding browning intensity was 0.27,0.42,and 0.46,respectively.The physicochemical properties of SPI-OKGM were significantly higher than those of the SPI and SPI+OKGM mixture.The emulsification activity of SPI-OKGM 26.80,SPI-OKGM 42.98,and SPI-OKGM 59.66 was 63.32%,65.37%,and 70.50%higher than that of the SPI+OKGM mixture,respectively.The emulsion stability increased by 23.08 min,27.52 min,and 27.26 min,and the resistance to lipid oxidation increased by 26.56%,28.96%,and 23.34%respectively.Scanning electron microscopy results showed that SPI-OKGM exhibited a loose flake shape and reduced protein aggregation.This study provided a reference to improve the functional properties of KGM and expand the application of OKGM in the Maillard reaction.