Identifying Metabolites in Complex Extract of Sigararutang Coffee Beans with NMR Spectroscopy Method

Abstract

The sigararutang is a superior variety of arabica coffee fruiting continuously and has an exquisite taste. However, the chemical information of sigararutang coffee is still limited in the literature. In this paper, metabolites of sigararutang coffee were analyzed with 1H NMR spectroscopy and then further verified by 2D NMR techniques, comprising TOCSY, COSY, and J-Resolved. The samples used in this study were green beans of sigararutang coffee obtained from Malabar Mountain, Bandung, West Java, Indonesia. Accumulatively, 17 metabolites were successfully recognized in the extracts of sigararutang coffee, including sucrose, caffeine, trigonelline, 3-CQA, 5-CQA, 4-CQA, quinic acid, malic acid, lactic acid, citric acid, asparagine, alanine, lipid, myo-inositol, GABA, formic acid, and choline in the single-step analysis. In addition, some metabolites of sigarangutang coffee were quantified relatively by the integration of 1H NMR signals. Sucrose (6.62%, w/w) was the most rich component in the green coffee bean of the C.arabica var.sigararutang. The amounts of GABA, malic acid, and choline with concentrations below 0.1%, were also calculated successfully. This study demonstrated the ability of NMR techniques for identifying and quantifying metabolites in the extracts of sigararutang coffee without any separation.