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Effect of parboiling on decortication yield of millet grains and phenolic acids and in vitro digestibility of selected millet products

Bora, Pragyani, Ragaee, Sanaa, Marcone, Massimo
Food chemistry 2019 v.274 pp. 718-725
2,2-diphenyl-1-picrylhydrazyl, Panicum miliaceum subsp. miliaceum, Pennisetum glaucum, antioxidant activity, crop yield, digestible protein, glycemic index, in vitro digestibility, millets, milling, parboiling, phenolic acids, rice, starch
Parboiling is a common method used in rice processing to improve milling yield and physicochemical properties. The current study evaluates parboiling as a pre-treatment step in millet decortication and its impact on phenolic profile and in vitro digestibility of two traditional millet products, steam-cooked couscous and porridge, made from pearl (Pennisetum glaucum) and proso (Panicum miliaceum) millets. Parboiling increased decorticated yield of pearl and proso millet by 37% and 28% respectively. It resulted in significant (P < 0.05) rise in free and bound phenolic contents and DPPH (2,2-diphenyl-1- picrylhydrazyl) radical scavenging activity of the millet products. This method significantly (P < 0.05) changed starch digestion fractions of both products thereby reducing expected glycemic index (eGI) while the in vitro protein digestibility of products decreased by 14–17%. Parboiling could be an effective way to improve millet decortication yield as well as produce millet products with higher phenolic acids antioxidant activity and lower GI.