蛹虫草的稳定碳同位素和脂肪酸研究

Fatty Acids and Stable Carbon Isotope Ratios in Cordyceps militaris

摘要:

本文旨在对冬虫夏草替代品的脂肪酸组成和稳定碳同位素比值及其变异规律开展研究。采用元素分析-同位素比值质谱仪（EA-IRMS）先对8种冬虫夏草替代品（包括6种蛹虫草和2种虫草菌丝体）和1个冬虫夏草子座样品的稳定碳同位素比值进行测定，再采用化学方法将其中性油脂和极性油脂进行高效分离，并采用气相色谱-质谱联用仪（GC-MS）对中性油脂和极性油脂的脂肪酸组成进行测定；最后将检测结果与作者之前报道的冬虫夏草数据进行对比分析。对比研究表明，不同冬虫夏草替代品在稳定碳同位素比值、粗脂肪含量和脂肪酸组成上存在明显差异；冬虫夏草替代品的粗脂肪和不饱和脂肪酸含量低于冬虫夏草，显现出冬虫夏草的不可替代性；稳定碳同位素比值和脂肪酸组成是冬虫夏草替代品掺杂判识的两类重要标志。

Abstract:

This paper aims to study the fatty acid composition and stable carbon isotope ratios as well as their variational trends of several substitutes of Ophiocordyceps sinensis. Firstly, the stable carbon isotope ratios of eight substitutes of Ophiocordyceps sinensis, including six kinds of Cordyceps militaris and two kinds of Cordyceps mycelium, and one stroma sample of Ophiocordyceps sinensis were determined by elemental analysis-isotope ratio mass spectrometry (EA-IRMS). Then, the neutral and polar lipids were effectively extracted from the samples by a chemical saparation method, and their fatty acid compositions were measured by chromatography mass spectrometry (GC-MS). Finally, the measured data was compared with our previously-published data of Ophiocordyceps sinensis. Evident differences were found among different substitutes of Ophiocordyceps sinensis in their stable carbon isotope ratios, fat contents and fatty acid compositions. The contents of fat and unsaturated fatty acids in the substitutes were lower than those of Ophiocordyceps sinensis, exhibiting the irreplaceability of Ophiocordyceps sinensis. Results also showed that the stable carbon isotope ratios and fatty acid composition might be two important markers to discriminate the adulteration among the substitutes of Ophiocordyceps.