Sugar based legume authentication metod: snap bean vs faba bean

Legumes have a great importance in human diet due to their richness in proteins, fibers, carbohydrates and minerals. Moreover, legumes do not contain gluten, so their application is very wide lately. The aim of this paper was to develop a legume authentication method based on sugar composition. Two legume species were included in this research: snap bean (4 samples, 1-4) and faba bean (8 samples, 5-12). Before sugar extraction, lipids needed to be removed from the samples using solvent n-hexane for triple extraction of liposoluble compounds. Further, methanol was used as a solvent for extraction of sugars from the samples. Derivatization of the sugar compounds was performed using reagent trimethylsilyl-imidazole (TMSI). A GC-MS (gas chromatography coupled to mass spectrometry) analysis was performed and the obtained chromatograms were processed in term to identify the eluting compounds. Peak surface areas of identified sugar compounds were collected into a data matrix for further multivariate analysis. By performing hierarchical cluster analysis (HCA), a similarity dendrogram was obtained. Faba bean samples are grouped together in the same cluster with the similarity level of about 0.7. On the other hand, snap bean samples 1-3 are clustered together with the similarity level of also about 0.7, while snap bean sample 4 is an outlier showing the least similarity to all other analyzed samples. This sugar composition based method exhibits a strong potential in developing procedures for legume authentication.