Biochemical characterization of buckwheat main seed storage protein for its geographical traceability

The genus Fagopyrum has about 15 species distributed in different parts of the world. Among these species, only two types of buckwheat are used as food: common buckwheat (Fagopyrum esculentum) and Tartary buckwheat (Fagopyrum tartaricum). Buckwheat is a pseudocereal crop. Typically, buckwheat seed contains 55% starch, 12% protein, 4% lipid, 2% soluble carbohydrates and 7% total dietary fiber. Approximately 64% of the proteins are 13S globulins, whereas albumins are 12,5% and glutelins are 8%. The main seed storage protein belongs to the legumin protein family (sedimentation coefficients: 13S). It is an hexameric protein, where each monomer is formed by two different subunits linked by a disulphide bond. Previous studies have shown its isoforms can be subgrouped according to their charge, identified as “high charge isoform” and “low charge isoform” [1]. This work aimed to test if the structural characteristics of the 13S isoforms may allow to define the geographical origin and provenience of cultivated buckwheat. Achieving this goal is relevant for food traceability and consumer protection in global trading. In this study, we investigated different buckwheat varieties from different parts of the world: F. tartaricum and F. esculentum from Teglio (Valtellina) and other two Tartary buckwheat from China and Germany. A biochemical approach based on 2D electrophoresis analyses was suitable for highlighting the biodiversity. The results indicate that differences between Tartary and common buckwheat and samples with different geographical origins could be detected. [1] Capraro, J. Biomolecules 2020, 10(5), 795;