Food Science and Technology Program, School of Public Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia.
Food Chem. 2014 Mar 1;146:345-52. doi: 10.1016/j.foodchem.2013.09.057. Epub 2013 Sep 18.
A highly selective and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous identification and quantification of beta-casomorphin 5 (BCM5) and beta-casomorphin 7 (BCM7) in yoghurt. The method used deuterium labelled BCM5-d10 and BCM7-d10 as surrogate standards for confident identification and accurate and quantification of these analytes in yoghurt. Linear responses for BCM5 and BCM7 (R(2)=0.9985 and 0.9986, respectively) was observed in the range 0.01-10ng/μL. The method limits of detection (MLDs) in yoghurt extracts were found to be 0.5 and 0.25ng/g for BCM5 and BCM7, respectively. Analyses of spiked samples were used to provide confirmation of accuracy and precision of the analytical method. Recoveries relative to the surrogate standards of these spikes were in the range of 95-106% for BCM5 and 103-109% for BCM7. Precision from analysis of spiked samples was expressed as relative standard deviation (%RSD) and values were in the range 1-16% for BCM5 and 1-6% for BCM7. Inter-day reproducibility was between 2.0-6.4% for BCM5 and between 3.2-6.1% for BCM7. The validated isotope dilution LC-MS/MS method was used to measure BCM5 and BCM7 in ten commercial and laboratory prepared samples of yoghurt and milk. Neither BCM5 nor BCM7 was detected in commercial yoghurts. However, they were observed in milk and laboratory prepared yoghurts and interestingly their levels decreased during processing. BCM5 decreased from 1.3ng/g in milk to 1.1ng/g in yoghurt made from that milk at 0day storage and <MLQ at 1 and 7days storage. BCM7 decreased from 1.9ng/g in milk to <MLQ in yoghurts immediately after processing. These preliminary results indicate that fermentation and storage reduced BCM5 and BCM7 concentration in yoghurt.
建立并验证了一种高效液相色谱-串联质谱法，用于同时鉴定和定量酸奶中的β-酪啡肽 5（BCM5）和β-酪啡肽 7（BCM7）。该方法使用氘标记的 BCM5-d10 和 BCM7-d10 作为替代标准，以确保在酸奶中对这些分析物进行准确的鉴定和定量。在 0.01-10ng/μL 范围内，BCM5 和 BCM7 的线性响应（R2 分别为 0.9985 和 0.9986）。在酸奶提取物中的方法检测限（MLD）发现 BCM5 和 BCM7 分别为 0.5 和 0.25ng/g。对加标样品的分析用于确认分析方法的准确性和精密度。这些加标样品的回收率相对于替代标准在 BCM5 为 95-106%，在 BCM7 为 103-109%的范围内。加标样品分析的精密度表示为相对标准偏差（%RSD），BCM5 的值在 1-16%之间，BCM7 的值在 1-6%之间。BCM5 的日间重现性在 2.0-6.4%之间，BCM7 的日间重现性在 3.2-6.1%之间。验证后的同位素稀释 LC-MS/MS 方法用于测量 10 种商业和实验室制备的酸奶和牛奶样品中的 BCM5 和 BCM7。商业酸奶中均未检测到 BCM5 或 BCM7。然而，在牛奶和实验室制备的酸奶中观察到了它们，并且有趣的是，它们的水平在加工过程中降低了。BCM5 从牛奶中的 1.3ng/g 降低到 0 天储存时酸奶中的 1.1ng/g，在 1 和 7 天储存时低于检测限（MLQ）。BCM7 从牛奶中的 1.9ng/g 降低到加工后立即低于检测限（MLQ）的酸奶中。这些初步结果表明，发酵和储存降低了酸奶中 BCM5 和 BCM7 的浓度。
