基質輔助雷射脫附游離飛行時間質譜分析食用油中 三酸甘油酯

Abstract

本研究旨在建立以MALDI-TOF質譜法分析食用油三酸甘油酯之平台，並探討如何從MALDI-TOF質譜獲得更多的食用油成分資訊(三酸甘油酯CN:DB以外的資訊)。 先以MALDI-TOF質譜分析出16種食用油樣品的三酸甘油酯的脂肪酸總碳數及總雙鍵數(CN:DB)，再利用餘弦相似性分析，比較16個不同來源的食用油樣品。本研究將16種食用油樣品交叉比較，得到16 × 16個cosine值，每一個油種樣品與其他樣品比較之cosine值組合，可作為此油種樣品的特徵資料。 另外以MALDI-TOF/TOF分析豬油中相同碳數之三酸甘油酯(依照總碳數分為54個碳、52個碳、50個碳三群)的sn-2脂肪酸種類和sn-1/3脂肪酸種類。此脂肪酸資訊在未來可以應用於對照食用油中其他接有脂肪酸之微量成分(如phosphotidylcholine、MCPD ester、GE等)的脂肪酸組成是否合理，因為脂肪酸源自於同樣的生合成過程。並且三酸甘油酯的MALDI-TOF/TOF片段的餘弦相似性分析將6個劣質豬油樣品與三個市售豬油樣品區分開來。 本實驗整理出的MALDI-TOF圖譜上之與MCPDE及GE分子量相符之訊號，可供做進一步MALDI-TOF/TOF分析之參考。另外以與三酸甘油酯同樣的分析條件可分析出soybean lecithin中的phosphatidylcholine及lysophosphatidylcholine訊號，可做為未來平台延伸應用的參考。

An analytical platform for triacylglycerol (TAG) in edible oil by MALDI-TOF MS was established. 16 kinds of edible oil samples were analyzed by MALDI-TOF to obtain the information of total carbon number (CN) and total double bond number (DB) of the fatty acids on the TAG molecule. Cosine similarity analysis compared this 16 edible oil samples, and a table of cross comparison was established. Each edible oil sample in the table was assigned a series of cosine values (by the comparison with the other oils), and this series of values were characteristic to each sample. MALDI-TOF/TOF analysis of the lard sample was done on the three groups of TAGs of the same total carbon number (54 carbons, 52 carbons, 50 carbons, respectively). The sn-2 fatty acids and sn-1/3 fatty acids of each group of TAG were profiled. This profile could be used in rationalization of the fatty acid profile of other components in edible oil (minor components such as phosphotidylcholine, MCPD ester and GE that carry fatty acids in their structure), because the fatty acid biosynthesis usually can be traced to the same pathways in one organic body. Cosine similarity analysis was conducted on the TAG fragments in the MALDI-TOF/TOF analysis of lard samples, and the 6 low lard samples from TFDA were separated from the three lard sample from the market. Signals recognized as MCPD ester and GE were recognized in the MALDI-TOF spectra of lard samples, and can be used in further MALDI-TOF/TOF analysis for structure confirmation. Soybean lecithin was analyzed by the same method as TAG platform, and phosphatidylcholine and lysophosphatidylcholine signals were recognized, which could be used for more application of the MALDI-TOF platform developed in this study.