Metabolomic Analysis of the Degradation of Ascorbic Acid in a Commercial Green Tea Beverage Stored in PET Bottles

摘要

The purpose of this paper was to use metabolomics to investigate the chemical changes occurring in a green tea beverage packaged in polyethylene terephthalate (PET) bottles. The analysis methodology uses trimethylsilyl derivatization followed by gas chromatography-mass spectrometry (GC/MS) and multivariate analysis of principal component analysis (PCA). Bottled tea samples were stored at 4 degrees C (control) or 55 degrees C for 2 and 4 weeks. The samples were pretreated and then derivatized. The data set was analyzed using PCA. Two-dimensional PCA plots were constructed, then the stored tea samples were divided into three groups according to their storage temperature and duration. PCA showed a clear classification reflecting the deterioration of each tea sample and revealed two indicator compounds, identified by GC/MS and LC/MS analysis as xylonic acid and lyxonic acid (belonging to the aldonic acid family). These compounds, generated from ascorbic acid present in the green tea infusion, increased in concentration during storage at 55 degrees C. Thus, the results indicated the presence of a degradation pathway involving ascorbic acid in green tea products.