酶改性大豆种皮多糖对蛋白乳液稳定性的影响

Effect of enzymatically modified soybean polysaccharides on stability of protein emulsion

利用β-半乳糖苷酶、β-葡聚糖酶和木瓜蛋白酶酶解大豆种皮多糖(soybean hull polysaccharide,SHP),确定不同酶解作用对SHP乳化能力的影响,从基本成分的测定、红外、原子力显微镜、粒径分布、Zeta电位、乳化活性和乳化稳定性及多重光散射等方面来分析酶解后的多糖对乳液性质的影响。结果表明,4种多糖总糖含量为35%~50%,β-葡聚糖酶处理多糖(SHP modified byβ-glucanase,GLU)含量最高,为47.82%;β-半乳糖苷酶酶解多糖(SHP modified byβ-galactosidase,GAL)糖醛酸含量最高,为34.27%。5种乳液中,添加木瓜蛋白酶酶解多糖(SHP modified by papain,PAP)的乳液Zeta电位最高,为-29.1 mV,未添加多糖与添加SHP,PAP的乳液液滴均较大,添加GAL与GLU的乳液液滴粒径较小且分散均匀。添加GLU的乳液乳化活性指数(emulsifying activity index,EAI)及乳化稳定性指数(emulsifying stability index,ESI)分别是39.72 m 2/g和4198.11 min,活性及稳定性最好,而添加PAP与SHP的乳液EAI及ESI相近,均比未添加多糖的乳液好。同时,添加PAP的乳液剪切应力和黏度随剪切速率增大变化最明显。此外,多重光散射数据表明,添加GAL和GLU的乳液较稳定,而添加PAP的乳状液稳定性较差,未添加多糖乳液稳定性最差,14 d后出现乳液分层。因此,β-半乳糖苷酶、β-葡聚糖酶酶解后的多糖可以用于改善食品乳液的稳定性。

Soy hull polysaccharide(SHP)was modified byβ-galactosidase(GAL),β-glucanase(GLU)or papain(PAP)and their emulsifying ability were analyzed and characterized.The basic composition,Fourier transform infrared spectroscopy,atomic force microscope of different polysaccharides,particle size,Zeta potential,emulsifying activity index,emulsifying stability index,rheological properties and multiple light scattering of different emulsions were examined.The results showed that the GLU modified SHP had the highest total sugar content(47.82%),while the GAL modified SHP had the highest level of uronic acid(34.27%).Emulsion stabilized by PAP had the highest absolute value of Zeta potential,-29.1 mV and the droplet of the emulsion stabilized by GAL was smaller and uniform.The emulsions stabilized by SHP,PAP and soy protein isolate had the similar but larger droplet.The emulsification activity and emulsion stability of the GLU emulsion was the best,which was 39.72 m 2/g and 4189.81 min,respectively;the stability of PAP emulsion was similar to the SHP emulsion,and both of them were better than the emulsion without polysaccharide.In addition,the shear stress and viscosity of the PAP emulsion changed most obviously with the increase of shear rate.Multiple light scattering data indicated that the GAL emulsion and GLU emulsion were stable but the PAP emulsion had poor stability,and the emulsion without SHP was the worst in stability which became creaming after stored 14 d.Therefore,the polysaccharide modified withβ-galactosidase,β-glucanase can effectively improve the stability of the emulsion.