Analysis of coffee seed vigor by extractive electrospray ionization mass spectrometry

Water extracts of coffee seeds of various ages were analyzed in positive ion mode by extractive electrospray ionization mass spectrometry (EESI-MS) without any sample pretreatment, and the typical metabolites were identified by tandem mass spectrometry. Further assessment using principal component analysis (PCA), cluster analysis (CA), and discriminant analysis (DA) demonstrated that a combination of EESI-MS and multivariate analysis could effectively distinguish coffee seeds with different vigor. In PCA, the first three principal components explained 99.3% of the total variation, and coffee seeds with the same vigor were clustered closely together in CA with an accuracy of 100%. In DA, both the accuracy rate of discrimination of the training samples and the success rate of cross validation analysis were 100%. We concluded that coffee seeds with diverse vigor could be differentiated by EESI-MS coupled with multivariate analysis, providing a novel, sensitive, and rapid measurement of seed vigor in coffee.