Profiling of carbonyl compounds in fresh cabbage with chemometric analysis for the development of freshness assessment method

Abstract The aim of this study was to screen the distribution of carbonyl compounds (CCs) in fresh cabbage as a sample model of multi-layered leafy vegetables for discovering the universal freshness marker of fresh produces. The distribution of CCs was observed in the three outer leaf layers of the cabbage. The profile of CCs in each leaf will guide the selection of which leaf is the appropriate part to be used to further discover a freshness marker of cabbage during storage treatment at the postharvest stage. The carbonyl compounds in each leaf were extracted using a mixture of chloroform and methanol (2:1). The extracted CCs from samples were derivatized with dansyl hydrazine. A high-performance liquid chromatography-mass spectrometer with multiplexed multiple reactions monitoring (MRM) was used for the comprehensive detection of carbonyl compounds. More than 400 peaks were observed in the MRM chromatogram from all leaves. The distribution of m/z values that represent CCs were analyzed employing the principle component analysis-discriminant analysis by relating it to the leaf position. The distribution of CC was different for each leaf where the leaves of the second and third layers were similar and significantly different from the leaves of the first layer. The accumulation of trans-2-hexenal was dominant in the first layer; therefore, the utilization of the first layer is not suitable as the part of the sample to discover the freshness marker of multi-layered leafy vegetables.