Abstract

In this study, sterols in milk fat of cow, goat, buffalo and camel were analyzed for their variability across different season and species. A GC–MS-SIM (gas chromatography- mass spectrometry-single ion monitoring mode) method was developed for accurate determination of sterols through the selection of correct set of target and reference ions in different time windows. The simple and rapid method enabled accurate analysis of sterols without subjecting them to derivatization. The sterols characterized in milk fat included cholesterol, lathosterol, desmosterol, lanosterol and dihydrolanosterol. Species compared to season had a pronounced effect on variability of sterols. Among the different species, goat milk contained the highest cholesterol level (325.18 mg 100 g⁻¹ fat) while minor sterols were most abundant in buffalo milk (20.62 mg 100 g⁻¹ fat). The content of minor sterols: lanosterol, lathosterol, desmosterol and dihydrolanosterol in milk of different animals varied from 5.94 to 9.11, 3.01 to 7.50, 0.60 to 2.77 & 0.57 to 1.25 mg 100 g⁻¹ fat respectively. Chemometric statistical approaches consisting of principal component analysis and hierarchical cluster analysis (PCA and HCA) were used to process the data. PCA was a suitable approach to find out the similarity and differences between different species and accounted for 96.6% of total variability in data. However, the variation based on season could not be explained well by PCA. HCAcould suitably classify the milch animals into four clusters based on sterol content.

Graphic abstract

中文翻译：

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基于化学计量学分析的印度不同奶牛乳脂中固醇的比较研究

摘要

在这项研究中，分析了牛，山羊，水牛和骆驼的乳脂中的固醇在不同季节和物种之间的变异性。开发了GC-MS-SIM（气相色谱-质谱-单离子监测模式）方法，可通过在不同时间窗口内选择正确的目标离子和参考离子组来准确测定固醇。简单，快速的方法可以对固醇进行精确分析，而无需进行衍生化。以乳脂为特征的固醇包括胆固醇，谷甾醇，去甾醇，羊毛甾醇和二氢羊毛甾醇。与季节相比，物种对固醇的变异性有显着影响。在不同物种中，山羊奶中胆固醇含量最高（325.18 mg 100 g ^-1水牛乳中次固醇含量最高（20.62 mg 100 g ^-1脂肪）。100 g ^-1脂肪中不同动物的牛奶中次要甾醇的含量分别为5.94至9.11、3.01至7.50、0.60至2.77和0.57至1.25 mg，变化范围分别为：羊毛甾醇，谷甾醇，去水甾醇和二氢羊毛甾醇。由主成分分析和层次聚类分析（PCA和HCA）组成的化学计量学统计方法用于处理数据。PCA是找出不同物种之间相似性和差异性的合适方法，占数据总变异性的96.6％。但是，PCA无法很好地解释基于季节的变化。HCA可以根据固醇含量适当地将家畜分为四类。

图形摘要