Differences in Flavor Characteristics of Coffee Drinks Originating from Thermal Sterilization Process

Abstract

Differences in flavor characteristics of coffee drinks originating from different thermal sterilization processes (ultra-high temperature (UHT) and retort sterilization) were investigated. The sensory evaluation by an analytical panel revealed that the sensory characteristics of a retort-sterilized product were significantly different from those of unsterilized and UHT-sterilized products, suggesting that the sensory characteristics of the UHT-sterilized product are more similar to those of the unsterilized product. The results of gas chromatography/olfactometry analysis revealed three odorants (2-furanemethanethiol, 3-(methylthio)propanal, and 3-mercapto-3-methylbutyl formate) whose flavor dilution (FD) factors decreased in the unsterilized, UHT-sterilized, and retort sterilized products in this order and eight odorants (2-((methylthio)methyl)furan, 3-mercapto-3-methyl-1-butanol, 3-methylbutyric acid, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 4-methylphenol, and three unidentified odorants) whose FD factors increased in the unsterilized, UHT-sterilized, and retort sterilized products in this order. Changes in these odorants, which decrease or increase with an increase in the F₀ value (sterilization value), which serves as an indicator of heating, supported the sensory evaluation results that the retort-sterilized product is significantly dissimilar to the unsterilized and UHT-sterilized products. Electronic nose and taste-sensing measurements further supported the sensory evaluation results.