运用SPE-GC/MS技术分析马克思克鲁维酵母对发酵乳中游离脂肪酸的影响

摘要

利用固相萃取及气相色谱质谱联用仪(solid-phase extraction-gas chromatography mass spectrometry,SPE-GC/MS)技术,分析以马克思克鲁维酵母菌(Kluyveromyces marxianus)和乳酸菌(Streptococcus thermophilus,ST;Lactobacillus bulgaricus,LB)为混合发酵剂的发酵乳中游离脂肪酸含量变化,并对整个发酵过程进行跟踪监测.结果发现:使用SPE-GC/MS共检测出12种游离脂肪酸,其中短链及中链脂肪酸(C4-C12)有5种,长链饱和脂肪酸(C14-C18)7种,不饱和脂肪酸2种.2种发酵乳中主要的游离脂肪酸为棕榈酸、硬脂酸、肉豆蔻酸、油酸,且随着发酵时间的延长,混菌发酵乳中的含量显著高于双菌发酵乳(P ＜0.001).在发酵l～6h范围内,马克思克鲁维酵母菌的添加显著增加了双菌发酵乳中游离脂肪酸的含量(P ＜0.001).%Mixed bacteria fermented milk was fermented from mixed culture of Kluyveromyces marxianus and lactic acid bacteria and was analyzed by the solid phase extraction and gas chromatography mass spectrometry.The whole fermentation process was monitored.The results showed that the total 12 kinds of free fatty acids were detected using SPE-GC/MS,including 5 kinds of short-chain and medium-chain fatty acids (C4-C12),7 kinds of long chain saturated fatty acids (C14-C18),2 kinds of unsaturated fatty acids.The main free fatty acids in the two kinds of fermented milk were palmitic acid,stearic acid,myristic acid,oleic acid,and with the extension of fermentation time,their contents in the mixed bacteria fermented milk were significantly higher than those in the double bacteria fermented milk (P ＜0.001).Within 1 ～ 6h of fermentation,Kluyveromyces marxianus significantly increased the contents of free fatty acids in double bacteria fermented milk (P ＜0.001).