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Abstract：
Factors influencing the sour taste of coffee and the properties of chlorogenic acid are not yet fully understood. This study aimed to evaluate the impact of roasting degree on pH-associated changes in coffee bean extract and the thermal stability of chlorogenic acid. Coffee bean extract pH decreased up to a chromaticity value of 75 but increased with higher chromaticity values. Ultraviolet-visible spectrophotometry and structural analysis attributed this effect to chlorogenic and caffeic acids. Moreover, liquid chromatography-mass spectrometry analysis identified four chlorogenic acid types in green coffee bean extract. Chlorogenic acid isomers were eluted broadly on HPLC, and a chlorogenic acid fraction graph with two peaks, fractions 5 and 9, was obtained. Among the various fractions, the isomer in fraction 5 had significantly lower thermal stability, indicating that thermal stability differs between chlorogenic acid isomers.
摘要：
影响咖啡酸味和绿原酸性质的因素尚未完全了解。本研究旨在评估烘烤程度对咖啡豆提取物pH相关变化和绿原酸热稳定性的影响。咖啡豆提取物的pH值降低至75的色度值，但随着色度值的升高而升高。紫外可见分光光度法和结构分析将这种作用归因于绿原酸和咖啡酸。此外，液相色谱-质谱分析确定了绿咖啡豆提取物中的四种绿原酸类型。绿原酸异构体在HPLC上广泛洗脱，和有两个峰的绿原酸级分图，获得馏分5和9。在各种分数中，组分5中的异构体具有显著较低的热稳定性，表明绿原酸异构体之间的热稳定性不同。
