本研究目的為探討台灣市售植物油如橄欖油、葵花油、芥花油與大豆油等大宗食用油之組成特性，包 含脂肪酸、三酸甘油酯之當量碳數 (equivalent carbon number, ECN)、植物固醇及生育酚等，並利用主成分分析 (principal component analysis, PCA) 針對上述各項油脂參數進行解析，以評估不同植物油間具顯著差異化的特 徵指標。分析結果顯示，橄欖油與大豆油、葵花油等兩種植物油之間具有較顯著差異的特徵指標以脂肪酸及 ECN為主，包含肉豆蔻酸 (myristic acid, C14:0)、棕櫚油酸 (palmitoleic acid, C16:1)、油酸 (oleic acid, C18:1)、亞麻 油酸 (linoleic acid, C18:2)、ECN 42、ECN 44、ECN 48及植物固醇β-sitosterol等；芥花油之花生酸 (arachidic acid, C20:0)、二十碳烯酸 (gadoleic acid, C20:1)、二十四碳烯酸 (nervonic acid, C24:1) 及brassicasterol等參數的含量則明 顯高於其他三種植物油，可作為區分芥花油與其他油種的代表性指標，其中二十四碳烯酸及brassicasterol僅存 在於芥花油中，為芥花油的重要特徵。本研究篩選出判別四種台灣常見市售植物油的特徵指標，有利於增進 油種鑑別的效率，提升油脂混摻辨別的準確性。

The aim of this study is to investigate the characteristics of several common commercial vegetable oils including olive oils, sunflower oils, canola oils and soybean oils in Taiwan. The oil compositions and some minor compounds such as fatty acid composition, triacylglycerol composition (equivalent carbon number, ECN), phytosterols and tocopherols of all oil samples were evaluated by the principal components analysis (PCA) for the classification of different vegetable oils and the measurement of factors with better discriminating power. The results show that the significantly different characteristic indicators for differentiating olive oils from soybean oils and sunflower oils are mainly fatty acids and ECNs, including myristic acid, palmitoleic acid, oleic acid, linoleic acid, ECN 42, ECN 44, ECN 48 and β-sitosterol. The arachidic acid, gadoleic acid, nervonic acid and brassicasterol contents of canola oils are significantly higher than other three kinds of vegetable oils, especially nervonic acid and brassicasterol exist only in canola oils, which means these parameters are important characteristics of canola oils. In this study, the characteristic indicators among these four common commercial vegetable oils were selected, which is beneficial to oil identification and improves discrimination accuracy of oil adulteration.