人常乳与牛常乳中全谱游离氨基酸和水解氨基酸的对比

以产后30～40 d的人常乳和牛常乳为原料,采用同位素标记相对和绝对定量结合高效液相色谱-串联质谱技术对人常乳和牛常乳中全谱游离氨基酸和水解氨基酸的种类及含量进行对比分析。结果表明,人常乳和牛常乳中游离氨基酸质量浓度分别为0.37 g/L和0.16 g/L,水解氨基酸质量浓度分别为2.5 g/L和3.3 g/L。在全谱游离氨基酸中,人常乳和牛常乳均检测到9种必需氨基酸以及15种非蛋白质编码氨基酸,分别检测到11种和7种非必需氨基酸,其中人常乳9种必需氨基酸、10种非必需氨基酸以及7种非蛋白质编码氨基酸质量浓度显著高于牛常乳(P0.05);在全谱水解氨基酸中,人常乳和牛常乳均检测到8种必需氨基酸、10种非必需氨基酸以及12种非蛋白质编码氨基酸,其中人常乳γ-氨基丁酸、牛磺酸、α-氨基正丁酸和β-丙氨酸质量浓度显著高于牛常乳(P0.05)。本研究对比分析人常乳与牛常乳中全谱游离氨基酸和水解氨基酸的种类和含量差异,为配方乳制品以及功能性食品的发展提供一定的参考。

Comparison of Full-Spectrum Free and Hydrolyzed Amino Acids in Human and Bovine Milks

For this experiment, we collected human and bovine milks at 30–40 days postpartum. Isobaric tags for relative and absolute quantification combined with high performance liquid chromatography-tandem mass spectrometry (iTRAQ-HPLCMS/ MS) was used to compare the composition of full-spectrum free and hydrolyzed amino acids in milk samples. The results indicated that total free amino acid content was 0.37 and 0.16 g/L in human and bovine milks, and total hydrolyzed amino acid content was 2.5 and 3.3 g/L, respectively. Among the full-spectrum free amino acids, 9 essential amino acids and 15 non-protein amino acids were detected in both milks, and 11 and 7 non-essential amino acids were detected in human and bovine milks, respectively. Moreover, 9 essential amino acids, 10 non-essential amino acids and 7 non-protein amino acids in human milk were significantly more abundant than in bovine milk (P < 0.05). Among the full-spectrum hydrolyzed amino acids, 8 essential amino acids, 10 non-essential amino acids and 12 non-protein amino acids were detected simultaneously in human and bovine milks. Moreover, the levels of γ-aminobutyric acid, taurine, α-amino-n-butyric acid and β-alanine in human milk were significantly higher than in bovine milk (P < 0.05). This study provides a theoretical basis for the development of milk formulaeand functional foods.