Using volatile compounds for the identification of coffee adulterants: marker compounds and non-targeted analysis

Coffee is one of the most highly valued, consumed and comercialized foods in the world. Due to its considerable importance, it has become the target of numerous adulterations. Detecting a possible adulteration and the presence of additional adulterants in coffee has become an issue of great concern mainly because the compounds used as adulterants exhibit physical features very similar to ground roasted coffee. Aiming to overcome these difficulties, this work reports the development and application of a relatively faster, highly effective and reliable method for the detection and identification of adulterations in roasted coffee through the analysis of the composition of the volatile fraction in the presence of adulterants such as rice, corn, soybeans and barley. The proposed method was based on gas chromatography coupled with mass spectrometry (GC-MS) and chemometric tools. The application of the method led to the exclusive identification of many compounds in the volatile fraction of the adulterants investigated. The adulterants, despite having compounds similar to coffee, differed in terms of their volatile profiles, and consisted mainly of hydrocarbons, aldehydes, esters and carboxylic acids. Among all the compounds identified, five compounds were found to be the main determinants of adulteration: 2-furanmethanol-acetate, 2-methoxy-4-vinylphenol, 5-methyl-2-furancarboxaldehyde, 2-furanmethanol and glycerol-1,2-diacetate.