Grains, starch and protein characteristics of rice bean (Vigna umbellata) grown in Indian Himalaya regions

•Himalayan Rice bean Germ plasm was evaluated.•Relationship among grains size and starch and protein properties was established.•Large seed size had less compact intracellular structure with large starch granules.•Landraces with higher grain hardness contains high amylose.•Higher seed weight showed higher amylose content and higher thermal stability.

The grain, starch and protein characteristics of twenty rice bean lines were evaluated. The relationship between grain and starch properties was described using Principal Component Analysis (PCA). Seed weight was positively correlated with swelling capacity, hydration capacity, soaked and cooked seed hardness; and negative with ash content. Protein, ash and fat content of the lines ranged between 18.64 to 20.4%, 3 to 4.26% and 0.30 to 1.98%, respectively. Amylose content of starch varied between 21.12 and 60.14%. PCA revealed that the lines with higher seed weight had starch with lower amylose content and higher peak and breakdown viscosity. Lines with higher amylose content showed higher cooked grain hardness. Protein profiling revealed a total 27 major proteins of 103-15 kDa consisting of high MW (103.0, 92.0, 63.0 kDa), medium MW (58.0, 56.0, 50.0, 33.0-31.0 kDa) and low MW (29.0-20.0 kDa).