基于UPLC-MS/MS探究烘焙程度对咖啡豆中有机酸含量影响

Exploring the Effect of Roasting Degree on the Content of Organic Acids in Coffee Beans Based on UPLC-MS/MS

为探究烘焙工艺对咖啡豆口感的影响,本文研究了烘焙程度对咖啡豆中有机酸含量的影响。采用新建立超高效液质联用法(UPLC-MS/MS)测定不同烘焙条件下7种有机酸的含量。结果表明:7种有机酸化合物在0.5~20.0 mg/kg范围内线性关系良好,决定系数均大于0.990。7种有机酸的加标回收率在81.9%~104.7%,RSD为0.53%~6.64%。洪都拉斯咖啡豆样品检测结果显示随烘焙程度增加,苹果酸和柠檬酸含量下降,富马酸含量先升后降,琥珀酸、酒石酸、莽草酸和奎尼酸含量上升。轻度烘焙下苹果酸与柠檬酸总量最高,达到1201.5 mg/kg,酸度最佳;奎尼酸含量最少,为1363.7 mg/kg,涩度最低。肯尼亚、印尼、巴西、萨尔瓦多咖啡豆中有机酸在相同烘焙条件下表现相似。

The influence of roasting degrees of coffee beans on contents of organic acids which directly affect the coffee taste was investigated in this study,using a newly established ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)method to measure seven kinds of organic acids.The method showed a good linearity over the range of 0.5~20.0 mg/kg for 7 organic acids with R2>0.990.Recovery rates of 7 organic acids were 81.9%~104.7%at three spiked levels in roasted coffee beans and the relative standard deviations were 0.53%~6.64%.Honduras coffee bean samples results showed that with increasing roasting degree,the contents of malic acid and citric acid decreased gradually,fumaric acid content first increased and then decreased,succinic acid,tartaric acid,shikimic acid as well as quinic acid gradually increased.Light roast had the highest total contents of malic acid and citric acid and lowest content of quinic acid at a concentration of 1201.5 mg/kg and 1363.7 mg/kg,respectively,showing the best taste.Organic acids of coffee beans from Kenya,Indonesia,Brazil and Salvador showed the similar regular changes in the roasting process.