白酒糟醇溶蛋白的磷酸化改性及功能性质

酒糟是酿酒产业的最大副产物。酒糟富含醇溶蛋白,然而由于水溶性差,限制其进一步应用。采用醇碱法从清香型白酒糟中提取醇溶蛋白(prolamin from distiller’s grains, PDG),用三聚磷酸钠对PDG进行磷酸化改性,通过溶解度、持水性、持油性、乳化性等方面的分析,研究磷酸化改性对PDG功能性质的影响。结果表明,醇碱法提取的白酒糟PDG主要由4种不同分子质量的蛋白组成,原材料酒糟粉粉碎度影响PDG的提取率,粒度小时有利于提高蛋白提取率,以200目细粉为原料时PDG的提取率可达22.69%±0.26%。差示扫描量热实验结果显示PDG的热变性温度为123.47℃,PDG具有良好的热稳定性。傅里叶红外光谱结果表明与三聚磷酸钠反应后磷酸基团修饰到PDG上。磷酸化改性改善了PDG在水中的溶解度,30℃时磷酸化后PDG的溶解度较PDG提高了3.53倍,达到943.08±16.04μg/mL。由于引入磷酸基团,PDG的功能性质显著改善,磷酸化改性后PDG较PDG的持水性和持油性分别增加了44.9%和33.8%(30℃),乳化性及乳化稳定性分别提高了54.9%和3.6倍(pH10)。...

Phosphorylated Modification and Functional Properties of Prolamin from Baijiu Distiller's Grains

Distiller's grains are the major by-product in spirits industry. Baijiu distiller's grains after fermentation and distillation are rich in prolamin. However, the poor water solubility of prolamin from distiller's grains (PDG) limits its further application. In this work, PDG was extracted by ethanol-alkali method and phosphorylated with sodium tripolyphosphate (STP). Furthermore, the effect of phosphorylation on the functional properties of PDG was evaluated by water solubility, water holding capacity, oil holding capacity and emulsion capacity. The results showed that PDG extracted by ethanol-alkali method was mainly composed of four proteins with different molecular weights. The extraction rate of PDG was affected by the crushing degree of distiller’s grains powder, and small particle size was conductive to improve the protein extraction rate. The extraction rate of PDG reached 22.69%±0.26% when the powder was 200 mesh. The differential scanning calorimeter results indicated that PDG possessed good thermostability with the denaturation temperature of 123.47 ℃. Fourier transform infrared spectrometer (FTIR) results showed that PDG was modified with phosphate groups after reaction with STP. The water solubility of PDG after phosphorylation was improved and it was 3.53 times higher than that of PDG, reaching 943.08±16.04 μg/mL at 30 ℃. Due to the combination of phosphate groups, the functional properties of PDG were significantly improved. Compared with PDG, the water holding capacity and oil holding capacity of phosphorylated PDG at 30 ℃ were increased by 44.9% and 33.8% respectively, and the emulsifying property and emulsifying stability at pH10 were increased by 54.9% and 3.6 times respectively. The improvement of the functional properties was conductive to the expansion of PDG's application fields. This work laid a foundation for the high added-value utilization of distiller's grains.