壳聚糖对低脂牛乳凝块流变特性与蛋白回收率的影响

Effect of Chitosan on the Rheological Properties and Protein Recovery of Low-fat Rennet-induced Curd

为改善低脂干酪质地坚硬的缺陷,本研究在脱脂乳中分别添加0.01%,0.02%,0.03%的壳聚糖,通过监测牛乳经酶凝作用后形成的凝块的理化及流变特性的变化,探讨应用壳聚糖改善低脂干酪品质的可行性。试验结果表明,添加壳聚糖后凝块的水分含量显著降低(P<0.05),蛋白质含量及回收率显著提高(P<0.05)。其中壳聚糖添加量为0.03%时,凝块蛋白回收率为80.77%,产率为8.77%,显著高于对照组(P<0.05);同时,添加壳聚糖显著地增大了凝块的弹性模量值(P<0.05),显著地降低了黏弹特性值(tanδ值)(P<0.05);壳聚糖的添加虽对酪蛋白糖巨肽(CMP)的释放量和释放速率没有显著性影响(P<0.05),但显著性影响凝胶的形成速率和最终的凝胶强度(P<0.05)。壳聚糖对低脂凝块的质地及流变性无显著性影响,可增加低脂凝块的蛋白回收率。

Chitosan was added to skim milk at the concentration of 0.01%, 0.02%, and 0.03% to improve the texture of low-fat rennet-induced curd. The physicochemical and rheological propertiesof the curds were investigated. The caseinomacropeptide（CMP） release and the aggregation were also monitored to study the effect of chitosan on the gel formation process. Compared to the control, the presence of chitosan significantly decreased the moisture content and increased the protein content of the curds. The addition of 0.03% chitosansignificantly increased the protein recovery and curd yield. The storage modulus significantly increased and loss tangentsignificantly decreased with the increase in chitosan concentration. The CMP release during renting was not significantly affected by chitosan, however, the coagulation time was brought forward and the final gel strength significantlyincreased by the incorporation of chitosan. Our finding suggested that chitosan can used to increase the protein recovery.