Lentil seed coat as a source of phenolic compounds: influence of geographical origin and genotype

Lentils (Lens culinaris spp.) are promising legumes whose seed coats, the by-products produced from dehulling, can represent a valuable source of functional components. This work aimed at valorizing lentils seed coat as functional ingredients, by investigating its profile across 11 genotypes grown in two different growing locations in Italy. The total phenolic, flavonoids, and condensed tannins contents (mg/g dry weight,) ranged from 30.60 to 70.37 gallic acid equivalents, 0.86 to 2.21 catechin equivalents, and 22.34 to 77.49 catechin equivalents, respectively. The untargeted phenolic profiling through UHPLC/QTOF-MS, followed by multivariate statistics, revealed differences in the quality and quantity of polyphenols. A broad and diverse profile could be highlighted, including 420 compounds, mainly ascribable to flavonoids, phenolic acids, and low-molecular-weight phenolic compounds. Unsupervised cluster analysis highlighted that origin is hierarchically more important than genotype in determining the phenolic profiles. Pearson's correlation analysis showed that color was only partially related to phenolic content, while the geographic location and the genotype were more relevant. The significant accumulation of phenolics in some genotypes suggests that the genetic background should be taken into account, when lentils seed coat is to be included in food design as a sustainable source of phenolic compounds.