In this study, a peptide‐based method employing ultra high performance liquid chromatography electrostatic field orbitrap high‐resolution mass spectrometry and triple quadrupole mass spectrometry was developed for quantification of A1‐type and A2‐type β‐casein in milk from Yak, cows, and their offspring of crosses, Pien‐niu. The specific peptides of A1‐type and A2‐type β‐casein were screened and confirmed by protein software after analysis of high‐resolution mass spectrometry. The multiple reaction monitoring method was established based on the qualitative results, and isotope‐label peptides were used as internal standards. The linear correlation coefficients of this method were >0.99. The relative standard deviations of repeatability test were 0.2‐3.6%. The recovery rate ranged from 93.3 to 114.4% with relative standard deviations <6% at three different spiking levels. The method was applied to analyze 45 milk samples from different species. The results showed that β‐casein in Yak and Pien‐niu milk was about 30% higher than that in cow milk. Furthermore, the β‐casein in the Yak milk only contains A2‐type β‐casein. A1‐type and A2‐type β‐casein coexist in most samples of Pien‐niu and cow milk, a few samples contain only one type of β‐casein. These results provide further understanding in nutritional value of milk from Yak and Pien‐niu.

中文翻译：

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用高效液相色谱-高分辨质谱和串联质谱分析麦瓦牦牛和片牛乳中的 A1 型和 A2 型 β-酪蛋白

在这项研究中，开发了一种采用超高效液相色谱静电场轨道阱高分辨率质谱和三重四极杆质谱的基于肽的方法，用于定量牦牛、奶牛、奶牛、和他们杂交的后代，貔貅。A1型和A2型β-酪蛋白的特异性肽经高分辨率质谱分析后通过蛋白质软件进行筛选和确认。基于定性结果建立多反应监测方法，同位素标记肽段作为内标。该方法的线性相关系数>0.99。重复性测试的相对标准偏差为0.2-3.6%。回收率范围为 93.3% 至 114.4%，相对标准偏差 < 在三个不同的加标水平下为 6%。该方法用于分析来自不同物种的 45 份牛奶样品。结果表明，牦牛乳和片牛乳中的β-酪蛋白含量比牛奶高出约30%。此外，牦牛乳中的β-酪蛋白仅含有A2型β-酪蛋白。A1型和A2型β-酪蛋白共存于大部分片牛和牛奶样品中，少数样品仅含有一种β-酪蛋白。这些结果为进一步了解牦牛乳和片牛乳的营养价值提供了依据。A1型和A2型β-酪蛋白共存于大部分片牛和牛奶样品中，少数样品仅含有一种β-酪蛋白。这些结果为进一步了解牦牛乳和片牛乳的营养价值提供了依据。A1型和A2型β-酪蛋白共存于大部分片牛和牛奶样品中，少数样品仅含有一种β-酪蛋白。这些结果为进一步了解牦牛乳和片牛乳的营养价值提供了依据。