單、雙酸甘油酯油於加熱下生成3-單氯丙二醇酯與縮水甘油酯之模型探討

Abstract

雙酸甘油酯油 (diacylglycerol oil) 是以雙酸甘油酯為主成分的食用油。外觀及用途與一般由三酸甘油酯組成之食用油無異，具有不易被腸道吸收的優點。然而，雙酸甘油酯及單酸甘油酯是可能致癌物質3-單氯丙二醇酯 (3-monochloro-1,2-propanodiol ester, 3-MCPD-E) 及縮水甘油酯 (glycidyl ester, GE) 的主要前驅物。本研究將單棕櫚酸甘油酯、1,3-雙棕櫚酸甘油酯及兩者之混和物 (單:雙 = 2:8、5:5、8:2) 與氯化四丁基胺進行高溫反應，以氣相層析質譜儀分析3-單氯丙二醇酯、縮水甘油酯及棕櫚酸甘油酯含量，以離子層析測定游離氯離子含量變化。藉由模型試驗，了解雙酸甘油酯與單酸甘油酯對3-MCPD-E及GE生成的影響，作為雙酸甘油酯油配方參考。數據顯示，溫度愈高，愈易生成3-MCPD-E及GE，於220℃加熱 10 分鐘時，3-MCPD-E生成量就已高於在180℃加熱 60 分鐘。在220℃加熱超過30 分鐘，3-MCPD-E可能因降解為脂肪酸甘油酯而含量下降。雙酸甘油酯與單酸甘油酯並存時，具加乘效應，無法以純單、雙酸甘油酯的生成結果，線性加成計算混和物的3-MCPD-E及GE生成量。混和物中，若單酸甘油酯比例愈高，愈易生成3-MCPD-E；雙酸甘油酯比例愈高，愈易生成GE。若要降低雙酸甘油酯油生成3-MCPD-E及GE的風險，可調整單、雙酸甘油酯所占比例，以不同加熱溫度、時間等情境評估，與產品實際使用情況連結。

Diacylglycerol oil is one of the edible oils which is mainly composed of diglycerides. It has been recognized to possess many health benefits such as reducing fat accumulation in the body. However, diglyceride and monoglyceride is the precursor of carcinogenic compounds, 3-monochloro-1,2-propanodiol ester (3-MCPD-E) and glycidyl ester (GE). In this study, monopalmitin, 1,3-dipalmitin and their mixture (20:80, 50:50 and 80:20 ratio) was heated with tetrabutylammonium chloride at various temperatures (140-220°C) and durations (5-60 min) in order to simulate thermal processing of mono- and di-acylglycerol oil. The 3-MCPD-E, GE and palmitin content was determined by GC/MS and the free chloride ion content was determined by ion chromatography. Result showed that the higher temperature resulted in higher 3-MCPD-E and GE content. 3-MCPD-E content of system heated in 220℃ for 10 minutes is already significantly higher than that heated in 180℃ for 60 minutes. Due to synergy, the 3-MCPD-E and GE content in mixture could not be calculated by synthesis condition of pure monopalmitin and 1,3-dipalmitin. In mixture, high ratio of monopalmitin showed greater tendency to form 3-MCPD-E; whereas, high ratio of 1,3-dipalmitin favored GE. Conclusively, ratio of different glyceride could be optimized to reduce 3-MCPD-E and GE formation of diglyceride oil and the condition of heating temperature and time should be carefully assessed.