Bioactive compounds of whole, dal, milling byproduct and fractions of milling byproduct of pigeonpea (Cajanus cajan L.)

Abstract

Milling of pigeonpea is an essential process to improve culinary properties. Byproducts obtained from the milling have many bioactive components which can have significant favorable effects on human health. In commercial mills, pigeonpea dal recovery is about 70% against the potential dal recovery of 85%. As the seed coat is tightly attached to the cotyledons due to the presence of a gum layer in between. During abrasive dehusking, a commonly adopted method in commercial mills, about 15% of protein-rich peripheral cotyledons get mixed with seed coat. The milling byproduct thus obtained includes pulse proteins in the form of broken, powder of cotyledons, and phenol and antioxidant rich husk. The present study focuses on biochemical estimation of pigeonpea whole, dehusked splits (dal), milling byproduct, and fractions of milling byproduct. The husk and the broken fraction of milling byproduct (about 75% of the byproduct) are rich in phenolic compounds, antioxidants, and dietary fiber, whereas the remaining cotyledon powder fraction is found to be rich in protein. These components were separated and analyzed for biochemical estimations. The results indicate that cotyledon powder separated from pigeonpea milling byproduct contains the highest protein (20.6%). Husk fraction of the byproduct is reported to have maximum total phenolic content (845.55 mg GAE/100g) and total antioxidant activity (59.68 m mole TE/100 g). Dehusked splits were observed to have the highest calorific value (386.17 kcal/100g). Till now, the milling byproduct is used as low-value cattle feed. Results of the biochemical studies reveal that protein, phenol and antioxidant-rich pigeonpea milling byproduct can be utilized for the development of value-added edible products and also find applications in therapeutic usage.