不同甲酯化方法对瓜蒌籽油中十八碳三烯酸种类和含量的影响

Effect of Different Esterification Methods on the Type andContent of Octadecatrienoic Acid in Trichosanthes Kirilowii Maxim Seed Oil

摘要:

以索氏抽提的瓜蒌籽油为原料，测定其酸值、碘值和皂化值。分别采用酸催化法、碱催化法和BF3催化法对瓜蒌籽油进行甲酯化处理，利用气相色谱-质谱联用仪分析其脂肪酸中十八碳三烯酸的种类和含量。结果表明：瓜蒌籽油酸值为0.51 mg KOH/g，碘值为1.3398 g I2/g，皂化值为1.9143 g KOH/g。酸催化法鉴定出5种十八碳三烯酸，为栝楼特征性脂肪酸-瓜蒌酸、梓树酸、α-桐酸、γ-亚麻酸和α-亚麻酸，含量分别为6.43%、9.5%、7.00%、5.82%和1.52%；碱催化法和BF3催化法均鉴定出4种，为瓜蒌酸、α-桐酸、梓树酸和α-亚麻酸，其含量分别为31.24%和27.17%、3.33%和3.56%、1.23%和2.02%和0.38%和0.78%。结论：瓜蒌籽油品质符合国家食用油标准，可进一步开发利用；碱催化甲酯化法对十八碳三烯酸的异构效应最小，更适合用于瓜蒌籽油脂肪酸分析。

Abstract:

Trichosanthes kirilowii Maxim. seed oil extracted by Soxhletex traction were used as material. The acid value, iodine value and saponification value were analyzed. Trichosanthes kirilowii Maxim seed oil were esterified by acid catalyst, alkali catalyst and BF3 catalyst.The differences in type and content between the different kinds of octadecatrienoic acid were studied via gas chromatography-mass spectrometry (GC-MS). The results showed that the acid value, the iodine value and the saponification value were 0.51 mg KOH/g, 1.3398 g I2/g and 1.9143 g KOH/g. 5 octadecatrienoic acids were identified by acid-catalyzed esterification method, being of punicic acid (6.43%),catalpa acid (9.5%), α-eleostearic acid (7%), γ-linolenic acid (5.82%), and α-linolenic acid (1.52%). 4 octadecatrienoic acids were identified by alkali-catalyzed esterification method and BF3- catalyzed esterification method, being of punicic acid (31.24% and 27.17%), α-eleostearic acid (3.33% and 3.56%), catalpa acid (1.23% and 2.02%) and α - linolenic (0.38% and 0.78%). The quality indexes of the Trichosanthes kirilowii Maxim. seed oil met the national standards and it could be popularized. Alkali-catalyze esterification method was the most suitable method for Trichosanthes kirilowii Maxim. seed oil because of the minimum isomerization.