Color Darkening and Pyrazine Accumulation Associated with Apparent Roasting Intensity and Aroma Quality in Commercial Sesame Paste

Commercial sesame paste exhibits substantial variations in color and aroma, reflecting differences in raw materials and commercial processing conditions, including roasting. This study investigated 15 commercial sesame paste products to characterize associations among color/browning characteristics, sensory attributes, and aroma-active chemical profiles. Across the commercial samples, darker color and higher browning index (BI) values were generally associated with stronger roasted nutty and burnt attributes and weaker grassy notes. Higher pyrazine levels were also observed in samples exhibiting more pronounced apparent roasting-related aroma characteristics and were positively associated with roasted nutty and burnt attributes. GC-O and OAV screening, together with exploratory PLSR further analysis, indicated that Strecker aldehydes, pyrazines, and phenolic compounds were candidate contributors to the observed sensory differences. In aroma addition experiments, under the tested addition conditions, the R mixture containing 2-methylbutanal and selected pyrazines enhanced roasted nutty intensity, whereas the B mixture containing guaiacol and 4-vinyl-2-methoxyphenol enhanced burnt/smoky intensity under the tested addition conditions. These findings demonstrate that color/browning characteristics and aroma-active compound profiles provide complementary information for characterizing apparent roasting-related differences and aroma quality in commercial sesame paste, without representing direct measures of controlled roasting degree.