【摘要】 通过凯氏定氮法、高效液相色谱法和氨基酸分析仪研究了离心预除菌的UHT乳（C-UHT）和常规UHT乳（N-UHT）在常温6个月贮藏过程中乳蛋白和氨基酸成分的变化。热处理和贮藏过程中乳清蛋白质量浓度逐渐降低，非蛋白氮（NPN）质量分数逐渐增加，N-UHT和C-UHT的NPN质量分数从4.2%分别增加到8.7%和7.9%。热处理导致部分酪蛋白胶束解聚和酪蛋白组分进入了乳清相，乳清蛋白聚合进入胶束相，贮藏过程中这种作用持续进行。N-UHT和C-UHT中酪蛋白的解聚量分别为28.6%和22.6%，乳清蛋白的聚合量分别为8.5%和11.3%。热处理导致所有的乳蛋白组分发生了降解，贮藏过程中乳蛋白继续降解。N-UHT和C-UHT中总蛋白由39.81 g/L分别降解到29.57 g/L和31.42 g/L；游离氨基酸总量由原乳的31.4 mg/L增加到35.1～35.7 mg/L。C-UHT乳的乳蛋白降解和乳蛋白相转移程度显著低于N-UHT乳。更多还原

【Abstract】 This study focuses on the effect on milk protein and amino acid compositions of bactofugation UHT milk(C-UHT) and normal UHT milk(N-UHT) during 6 months of storage at room temperature by Kjeldahl method, high performance liquid chromatography and amino acid analyzer. It was revealed that during heat treatment and storage, whey protein mass concentration decreased and non-protein nitrogen(NPN)mass fraction increased. NPN of N-UHT and C-UHT mass fraction increased from 4.2% to 8.7% and 7.9% respectively.During heat treatment, some depolymerized casein micelles migrated into the whey phase and the polymerised whey protein migrated into the micelle phase. The amount of depolymerized casein in N-UHT and C-UHT was 28.6% and 22.6% respectively, and the amount of polymerized whey protein was 8.5% and 11.3% respectively. Heat treatment degraded all milk protein components and this degradation continued during storage. The total protein in N-UHT and C-UHT was degraded from 39.81 g/L to 29.57 g/L and 31.42 g/L respectively,and the total free amino acids increased from 31.4 mg/L to 35.1～35.7 mg/L. The degree of milk protein degradation and phase transfer of CUHT milk was significantly lower than that of N-UHT milk.更多还原