Meyer Marjolaine D, Terry Leon A
Plant Science Laboratory, Cranfield University, Bedfordshire MK43 0AL, United Kingdom.
J Agric Food Chem. 2008 Aug 27;56(16):7439-45. doi: 10.1021/jf8011322. Epub 2008 Aug 5.
Methods devised for oil extraction from avocado (Persea americana Mill.) mesocarp (e.g., Soxhlet) are usually lengthy and require operation at high temperature. Moreover, methods for extracting sugars from avocado tissue (e.g., 80% ethanol, v/v) do not allow for lipids to be easily measured from the same sample. This study describes a new simple method that enabled sequential extraction and subsequent quantification of both fatty acids and sugars from the same avocado mesocarp tissue sample. Freeze-dried mesocarp samples of avocado cv. Hass fruit of different ripening stages were extracted by homogenization with hexane and the oil extracts quantified for fatty acid composition by GC. The resulting filter residues were readily usable for sugar extraction with methanol (62.5%, v/v). For comparison, oil was also extracted using the standard Soxhlet technique and the resulting thimble residue extracted for sugars as before. An additional experiment was carried out whereby filter residues were also extracted using ethanol. Average oil yield using the Soxhlet technique was significantly (P < 0.05) higher than that obtained by homogenization with hexane, although the difference remained very slight, and fatty acid profiles of the oil extracts following both methods were very similar. Oil recovery improved with increasing ripeness of the fruit with minor differences observed in the fatty acid composition during postharvest ripening. After lipid removal, methanolic extraction was superior in recovering sucrose and perseitol as compared to 80% ethanol (v/v), whereas mannoheptulose recovery was not affected by solvent used. The method presented has the benefits of shorter extraction time, lower extraction temperature, and reduced amount of solvent and can be used for sequential extraction of fatty acids and sugars from the same sample.
从鳄梨（Persea americana Mill.）中果皮提取油脂的方法（如索氏提取法）通常耗时较长，且需要在高温下操作。此外，从鳄梨组织中提取糖分的方法（如80%乙醇，体积/体积）无法方便地对同一样品中的脂质进行测量。本研究描述了一种新的简单方法，该方法能够从同一鳄梨中果皮组织样品中依次提取并随后定量分析脂肪酸和糖分。对不同成熟阶段的鳄梨品种哈斯果实的冻干中果皮样品，用己烷匀浆提取，提取的油脂用气相色谱法定量分析脂肪酸组成。所得滤渣很容易用于甲醇（62.5%，体积/体积）提取糖分。为作比较，还用标准索氏技术提取油脂，所得的滤筒残渣按之前的方法提取糖分。还进行了一项额外实验，即用乙醇提取滤渣。尽管差异仍然非常微小，但索氏技术的平均出油率显著高于（P < 0.05）用己烷匀浆法获得的出油率，且两种方法提取的油脂提取物的脂肪酸谱非常相似。随着果实成熟度的增加，油脂回收率提高，采后成熟过程中脂肪酸组成的差异较小。去除脂质后，与80%乙醇（体积/体积）相比，甲醇提取在回收蔗糖和鳄梨糖醇方面更具优势，而甘露庚酮糖的回收率不受所用溶剂的影响。所提出的方法具有提取时间短、提取温度低、溶剂量减少的优点，可用于从同一样品中依次提取脂肪酸和糖分。
