Optimization of Heat pump-assisted dehumidified air drying (HPD) temperature on phytochemicals, drying characteristics and nutrient compound retention of drumstick by GC-MS and principle component analysis

Abstract

Drumstick (Moringa oleifera Lam.) is an incredible plant to humans because of its pharmacognostic and nutraceutical properties. M. oleifera contains vital nutrients such as minerals, vitamins, and phytochemicals like tannins and flavonoids. The present work aims to study the optimization and quality attributes retention in drumstick through Heat Pump-assisted dehumidified air Dryer (HPD) because the conventional drying process takes more time and energy, affecting the product quality and safety. Different solvents, such as ethanol, chloroform, hexane, acetone and ethyl acetate, were used to determine the presence of phytochemicals (alkaloids, tannins, flavonoids, steroids, terpenoids and saponins) in the drumstick. The phytochemicals were highly present in methanol and ethanol extracts from qualitative screening of drumstick. Dried drumstick powder was prepared by using fresh drumstick pieces, steam blanched for 2-5 min and then sulfated at 0.1 % for 10 min. After that, the dehydration process was performed at different temperatures (45, 55 and 65°C) in an HPD drier. HPD dried drumstick powder at 55⁰C was found to have maximum physicochemical properties, drying characteristics and higher retention of bioactive compounds with special reference to high powder recovery (97.22 %), excellent flowability and better retention of nutrients like β – carotene (174.49 mg), total antioxidant (266.02 mg), flavonoids (6.207 mg/RE), phenol (229.54 mg/GAE) and vitamin C (253.16 mg). The extract of fresh and HPD dried drumstick powder contained 50 major bioactive compounds such as 2,6-Dihydroxybenzoic acid 3TMS derivative, Butanal 2-ethyl-3-methyl- etc., these bioactive compounds act as various nutraceuticals and therapeutic values.