Metabolic profiling of Goji berry extracts for discrimination of geographical origin by non-targeted liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

The fruit of Lycium barbarum (Solanaceae), known as Goji berry, or wolfberry, has long been used in traditional Chinese medicine, and is increasingly becoming popular in Western diets due to its potential health benefits. The majority of commercially produced Goji berries come from certain regions in Asia. In this study we explored the discrimination of phytochemical content between four different geographic origins of Goji berries by applying non-targeted liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-qTOF-MS) metabolite profiling. Principal component analysis was able to clearly distinguish the berries by the geographic origin when applied to the non-targeted profiling data of Mongolian, Chinese and two Tibetan origin Goji berry extracts. Furthermore, partial least squares discriminant analysis (PLS-DA) provided indicative markers of discrimination between the different origins, and quality threshold cluster analysis classified the most discriminative compounds according to their occurrence between the different origins. The largest cluster included the most discriminative metabolites in the Mongolian variety, which was also seen as the most distant group in the PCA analysis as compared to the other countries of origin. Mongolian Goji berries were mainly characterized by significantly higher levels of several flavonol glycosides, such as quercetin and kaempferol glycosides; isomers of dicaffeoylquinic acid and phenolic acids such as coumaric acid. In addition to the various phytochemical metabolites identified, a pesticide compound was found especially in the extracts of Goji berries from China. The present non-targeted metabolite profiling proved to be a useful approach of the Foodomics field for assessment of geographical origin of berries