索氏提取法测定海洋微藻粗脂肪含量及其优化方法的研究

Improvement of soxhlet extraction used for determination of crude lipids content of marine microalgae

摘要:

微藻油脂含量是评价其作为生物柴油原料的关键指标。采用索氏提取法，以乙醚为溶剂，在60～80 ℃的温度条件下，对7种海洋微藻细胞内粗脂肪含量进行测定，并对提取方法做了优化。优化的方法是将样品预先在乙醚溶剂中浸泡一定时间，使部分油脂在乙醚溶剂中浸出，然后再按索氏方法进行脂肪抽提。结果显示，7种海洋微藻油脂含量都占干重的15%以上，其中牟氏角毛藻、湛江等边金藻和微绿球藻油脂含量最高，超过25%。结果还显示，传统方法和优化方法测定结果的差异低于3.5%，说明优化后的索氏提取法没有对测定结果造成显著影响。采用索氏提取优化方法不仅能够更彻底地提取微藻粗脂肪，而且还大大缩短提取时间，因此，优化后的索氏提取法具有提取效率高、提取成本低和提取完全等优点，并且该方法缩短了抽提时间，从而降低了乙醚等有机萃取剂因挥发而造成的污染。

Abstract:

The lipid content is a critical criterion for the evaluation whether the microalga was qualified as biofuel material. In the present study, the crude lipid of seven species of marine microalgae was extracted by ethyl ether using Soxhlet extraction method, under a temperature of approximately 60-80 ℃. The Soxhlet extraction method was improved by dipping the microalgae in ethyl ether for some time before leaching. The results show that the lipid contents were higher than 15% for the seven species of marine microalgae. The lipid contents of Nannochloropsis Oculata, Isochrysis zhanjiangensis and Chaetoceros muelleriwere are higher than 25%. Variation of the results acquired by the traditional method and the improved method was less than 3.5%, which indicated that there was no significant difference. Moreover, the crude lipid was extracted more thoroughly by the improved method, within a much shorter time. In conclusion, the improved Soxhlet extraction was more efficient, with lower cost and more thorough extraction. What’s more, the pollution caused by ethyl ether was reduced due to a shorter extraction time.