Metabolite Profiling of Giant Green Wax Apples (Syzygium samarangense) for Differentiation of the Maturity Stages and...

This study identifies the changes of metabolite fingerprinting and their potential role in biological activities at each maturity stage in fruits of the 'giant green' cultivar of wax apple. Different mature fruits were differentiated by using FTIR (Fourier transform infrared spectroscopy), GC─MS (gas chromatography-mass spectrometry) and GC─MS with united chemometric tools. The PCA (principal component analysis), HCA (hierarchical clustering analysis) and PLS-DA (partial least square-discrimination analysis) of FTIR and GC─MS data revealed the separation cluster within the maturity stages. Twenty-eight metabolites were identified from fruit that were classified into the following classes: alkane (9), alkene (4), ether (1), ester (7), alcohol (3), ketone (3) and lipid (1). A total of 18, 21 and 20 metabolites were identified from unripe, half-ripened and ripened fruits. The highest number of bioactive metabolites (13) with higher concentrations were detected from unripe fruits. PLS-DA model reported that three mature fruits improved their separation according to their maturity. The PLS (partial least square) model also showed a strong positive correlation between metabolite quantities and biological activities of unripe fruits. The number and concentration of the bioactive metabolites were highest in unripe 'giant green' wax apple fruits, which shows their potential role in the pharmaceutical and food industries.