Changes in the Volatile Profiles of Commercial Straight Pressed Tomato Juice Upon Heating

Abstract

Tomato juice is a popular beverage and a convenient cooking ingredient. Especially, straight pressed tomato juice (not from concentrate) maintains fresh flavor, showing different characteristics from the juice from concentrate. We studied changes in the profile of volatile compounds in straight pressed tomato juice upon heating. We heated two types of commercial packaged straight pressed tomato juices at 95 – 100°C for 0 – 5 h and extracted volatile compounds in each sample by headspace-solid phase microextraction. A total of 176 and 187 compound peaks were detected, of which 81 and 86 compounds were identified or tentatively identified by GC/MS analysis, respectively. Principal component analysis (PCA) indicated that the samples could be divided into six groups based on heating time; the volatile profiles changed in a time-dependent manner. Furthermore, seven chemicals were identified as heat markers using partial least squares (PLS) regression, namely 2-pentylfuran, phenylacetaldehyde, hexanal, furfural, cyclohexanone, β-damascenone, and 1,4-dimethylbenzene. A prediction model based on only these seven marker profiles for heating period, also showed good linear regression (R²＞0.987). Gas chromatography-mass spectrometry/olfactometry (GC-MS/O) analysis and quantification of these volatiles suggested that phenylacetaldehyde, hexanal, β-damascenone and 2-pentylfuran influence the flavor characteristics of tomato juice.