[关键词]
[摘要]
采用三聚磷酸钠(STP)对酪蛋白进行改性,在pH为9、STP的添加量为5%、温度为30 ℃的条件下磷酸化3 h,此时酪蛋白的磷酸化程度为18.18 mg磷/g酪蛋白。利用胰蛋白酶对不同磷酸化程度的酪蛋白进行酶解。研究了STP处理对酶解过程中水解度、水溶性氮含量、氨基氮和肽氮含量变化规律的影响,并且用分子排阻色谱(HPSEC)研究了酶解液中的MWD(分子量分布)。结果表明:磷酸化处理后,酪蛋白的水解度及酶解液中氨基氮含量较对照组显著提高(P<0.01),并且不同磷酸化程度的酪蛋白之间有显著差异(P<0.05)。磷酸化3 h的酪蛋白的酶解液中水溶性氮和肽氮含量显著提高(P<0.01)。磷酸化处理与对照组相比,其保留时间变短,并且在保留时间为12 min时出现新的吸收峰,磷酸化处理显著提高酶解液中分子量为2×104~3.5×104 u之间的多肽含量。
[Key word]
[Abstract]
Casein was phosphorylated using sodium tripolyphosphate (STP) under the following optimal conditions: 5% STP, 30 ℃ and pH 9. The degree of phosphorylation reached to the largest (18.18 mg phosphorus/g casein) after treatment for 3 h under above conditions. And then the different levels of phosphorylated casein were hydrolyzed with trypsin. The degree of hydrolysis, the changes of soluble nitrogen, aminonitrogen and peptide nitrogen contents during enzymatic hydrolysis process were studied. The molecular weight distribution (MWD) of hydrolysate was detected by high performance size exclusion chromatography (HPSEC). The results showed that the degree of hydrolysis and amino nitrogen content significantly (P<0.01) increased after phosphorylated, and obvious (P<0.05) differences were found between different levels of phosphorylation. In the hydrolysates of casein phosphorylated for 3 h, the soluble nitrogen and peptide nitrogen contents were significantly (P<0.01) improved. Compared with the control, the retention time of phosphorylated was shorter, and a new peak appeared at 12 min. The content of peptides with molecular weight between 2×104 u and 3.5×104 u increased obviously compared with the control.
[中图分类号]
[基金项目]
国家自然科学基金项目(31071496)