米糠蛋白酶解产物功能特性及乳液稳定性研究

Functional properties and emulsion stability of hydrolyzed rice bran protein

目的 改善米糠蛋白的溶解性,探讨米糠蛋白乳液的稳定性。方法 选用胰蛋白酶对米糠蛋白进行酶法改性,分析其在不同水解度下(1%、3%、7%)酶解产物的功能特性及不同pH、离子强度和温度对米糠蛋白酶解产物乳液的影响。结果 酶解可显著提高米糠蛋白的溶解性,在水解度7%时的溶解性最高;而酶解产物的起泡性、起泡稳定性、乳化性和乳化稳定性呈现先增加后下降的趋势,并在水解度为3%时达到最大值;经酶解后持油性显著增加(P<0.05),而持水性显著降低(P<0.05)。米糠蛋白及酶解产物乳液在不同pH下平均粒径和电位总体上呈现相似变化趋势,在等电点附近极不稳定,在pH 7~8时乳液趋于稳定;低水解度(1%、3%)的酶解产物乳液对高温和盐离子的抵抗能力高于米糠蛋白。结论 水解度为3%的酶解产物,其功能特性显著提升,制备的乳液在高离子强度和加热条件下较为稳定,该结果为米糠蛋白酶解产物制备食品乳液提供理论依据。

Objective To improve the solubility of rice bran protein and study the stability of rice bran protein emulsion. Methods Trypsin was used for enzymatic modification of rice bran protein, the functional properties of the hydrolysates at different conditions of hydrolysis(1%, 3%, and 7%) and the effects of different pH, ionic strength and temperature on the emulsion of the hydrolysates were analyzed. Results Enzymatic hydrolysis could significantly improve the solubility of rice bran protein, and the solubility was the highest when the hydrolysis degree was 7%. The foaming ability, foaming stability, emulsification and emulsification stability of the hydrolysates increased firstly and then decreased, and reached the maximum value when the degree of hydrolysis was 3%. The oil holding capacity increased significantly after enzymatic hydrolysis(P<0.05), while the water holding capacity decreased significantly(P<0.05). It was found that the mean particle size and the zeta potential of rice bran protein and its hydrolysates emulsion generally showed a similar trend at different pH, and they were extremely unstable near the isoelectric point, and tended to be stable at pH 7-8. The emulsion with low degree of hydrolysis(1%, 3%) had higher resistance to high temperature and salt ions than rice bran protein. Conclusion The functional properties of the hydrolyzed product with a degree of hydrolysis of 3% are significantly improved, under the condition of high ionic strength and heating, the emulsion is more stable. The results provide a theoretical basis for the preparation of food emulsion from hydrolyzed rice bran protein.