不同甲酯化方法对裂壶藻产油脂肪酸的影响及GCMS分析

为了研究不同的甲酯化方法对裂壶藻产油脂肪酸的影响,本文通过对裂壶藻进行发酵培养得到纯藻体,再经过酶法破壁、冷冻干燥得到干藻体后采用索氏提取法提取油脂。运用酸法、碱法和三氟化硼法三种甲酯化方法对藻油进行处理,基于气相色谱-质谱联用(GC-MS)技术分析了藻油中DHA(二十二碳六烯酸)等脂肪酸的组成和含量。结果表明:酸法、碱法、三氟化硼法分别鉴定出11种、19种和12种脂肪酸,占裂壶藻藻油总量的89.50%、97.88%和90.12%。其中酸法酯化的藻油中DHA占脂肪酸总量的38.89%;碱法酯化的藻油中DHA占脂肪酸总量的46.76%;三氟化硼法酯化的藻油中DHA占脂肪酸总量的40.54%。所以,碱法相较于酸法和三氟化硼法有明显的优势,更适合用于裂壶藻藻油的脂肪酸分析。进一步对碱法的甲酯化温度进行梯度实验,结果表明温度为55℃时,DHA的相对含量为47.45%,藻油的甲酯化效果最好。这一研究对长链多不饱和脂肪酸的检测鉴定有着重要的意义。

Effects of different methyl esterification methods on the production of fatty acids from Schizochytrium and GC-MS analysis

This study was aimed to explore the effects of different methyl esterification methods on the production of fatty acids from Schizochytrium. In this paper, the pure algae bodies were obtained by fermentation and culture, then the dried algae were acquired by enzymatic breaking and freeze-drying, soxhlet extraction method was used to extract the oil from the dried mycelium of Schizochytrium. The fatty acids in algal oil were esterified by three different methyl esterification methods, the composition and content of DHA(Docosahexaenoic acid)fatty acids in algal oil were analyzed by gas chromatography-mass spectrometry(GC-MS)technique. The results showed that 11 fatty acids were identified by acid-catalyzed esterification method, 19 fatty acids were identified by alkali-catalyzed esterification method and 12 fatty acids were identified by BF₃-catalyzed esterification method. The contents of the identified fatty acids accounted for 89.50%, 97.88% and 90.12% of oil of Schizochytrium, respectively. The content of DHA accounted for 38.89%, 46.76% and 40.54% of the total fatty acids, respectively. Therefore, alkali-catalyzed esterification method compared to acid-catalyzed and BF₃-catalyzed esterification method had obvious advantages, more suitable for fatty acid analysis of algae oil in Schizochytrium. Further more, the esterification temperature of the optimal alkali-catalyzed esterification method was conducted a gradient experiment, and the result showed that 55℃ was the optimal esterification temperature and the relative content of DHA was 47.45%. In a word, this research had an important significance for the detection of polyunsaturated fatty acid with long chain.