胰蛋白酶限制性修饰乳清浓缩蛋白纤维聚合物表面性质的研究

Surface Properties of Whey Protein Concentrate Fibrils Selectively Modified by Trypsin

为了研究胰蛋白酶限制性修饰对乳清浓缩蛋白(WPC)热致聚合物的微观形态及表面性质的影响,本文制备了胰蛋白酶在不同水解度(DH为0.2%、0.6%和1%)限制性修饰后的WPC在p H 2.0、90℃下热致聚合物,利用透射电镜分析了聚合物的微观形态特征,测定了不同聚合物的表面性质。结果表明,纤维聚合物较常规p H条件下形成的无定形聚合物具有较差的乳化活性和乳化稳定性以及较优的起泡和泡沫稳定性。胰蛋白酶修饰促进WPC纤维聚合物的形成,乳化活性较天然WPC形成纤维稍有提高;起泡性和泡沫稳定性显著提高,在DH为0.6%时起泡提高幅度最大,较天然WPC纤维提高了11.76%;在DH为1%时,泡沫稳定性较天然WPC纤维提高了12.59%。WPC经胰蛋白酶修饰后所形成更优的纤维结构以及表面疏水性的提高有利于其界面性质的提高。

To gain insight into the effect of proteolysis on the fibril formation and surface properties of whey protein concentrate（WPC）, it was selectively modified using trypsin at low degrees of hydrolysis（DH）（0.2%, 0.6%, and 1%） before adjusting the p H to 2.0 and heating at 90 ℃. The microscopic morphology of the aggregates was analyzed using transmission electron microscopy（TEM）, and surface properties of the aggregates were also evaluated. The results showed that the fibrils exhibited lower emulsifying activity index（EAI） and emulsifying stability index（ESA）, but higher foaming and foam stability than amorphous polymers under similar p H conditions. Trypsin modification was found to promote WPC fibril formation. The EAI was slightly increased compared to native WPC, while foaming and foam stability were significantly increased. The greatest increase in foaming（11.76%） was observed at a DH of 0.6%. At a DH of 1%, the foam stability was increased by 12.59%. Thus, trypsin modification of WPC improved fibril structure and increased surface hydrophobicity of the formed fibril, thus improving the interface properties.