Optimising drying conditions for maximum nutritional quality and bioactivity of Cucurbita pepo L var. fastigata flesh and seeds

Transformation of pumpkin flesh and seeds into dry flours increases their shelf stability and versatility. This study sought to optimise drying conditions for production of flour with high nutritional and nutraceutical value from flesh and seeds of C. pepo L var. fastigata using Response Surface Methodology, I optimal design.

Pumpkin flesh and seeds were dried following temperature time combinations got using I optimal design. All dry samples were tested for ascorbic acid, total carotenoids, total antioxidant capacity and starch digestibility. Seeds were also tested for in vitro protein digestibility, trypsin inhibitor activity, alpha tocopherol, beta tocopherol, and alpha tocotrienol.

The predicted optimum drying conditions for production of C. pepo L var. fastigata flour with maximum nutritional quality and bioactivity were 57°C; 6.9 hours for flesh and 60°C; 3.15 hours for seeds. The most influential model terms were temperature for resistant starch, in vitro protein digestibility, trypsin inhibitor activity, total carotenoids, alpha tocopherol, beta tocopherol and alpha tocotrienol; quadratic term of temperature and time for ascorbic acid; and drying time for total antioxidant activity of the flesh and temperature for antioxidant activity for seeds.

Dryer air flow rate was not included as a variable.

Results give, for the first time, an objective basis for choice of the drying conditions C. pepo L var. fastigata flesh and seeds for maximum nutritional and health benefits.