Determination of the fatty acid (FA) profile of milk fat generally involves total lipid extraction from liquid milk, transesterification and GC analysis. The lipid extraction step is time consuming and often employs toxic solvents such as chloroform. Two alternative methods are presented here that skip the lipid extraction step and allow the determination of FA composition via direct transesterification of dried milk and liquid milk respectively. We have shown that dried milk can be used directly in alkaline-catalysed methylation, whereas direct transesterification of both dried milk and fresh milk is feasible with acidic methanol. Both methods generate similar results as compared to the classical two-step method (i.e. lipid extraction and FA methylation) when optimised methylation parameters (temperature, time, milk and reagent volume) are followed. By omitting the lipid extraction step, these simplified one-step methods offer a much higher throughput and a reduced cost in FA composition analysis of milk samples.

中文翻译：

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一步一步制备乳脂中脂肪酸的样品制备方法。

乳脂中脂肪酸（FA）谱的确定通常涉及从液态乳中提取总脂质，酯交换和GC分析。脂质提取步骤很费时，并且经常使用有毒溶剂，例如氯仿。此处介绍了两种替代方法，它们跳过脂质提取步骤，并分别通过干奶和液态奶的直接酯交换反应确定FA组成。我们已经证明，干乳可以直接用于碱催化的甲基化反应，而干乳和新鲜乳都可以通过酸性甲醇直接酯交换。在优化的甲基化参数（温度，时间，温度和温度）下，与经典的两步法（即脂质提取和FA甲基化）相比，两种方法均产生相似的结果。牛奶和试剂量）。通过省略脂质提取步骤，这些简化的单步方法在牛奶样品的FA成分分析中提供了更高的通量并降低了成本。