Characterization of Freeze-dried Pumpkin Powders: Powder Quality and Nutrient Stability
Swathi, B.S *
Department of Postharvest Management, College of Agriculture, Vellayani, Kerala Agricultural University, Thiruvananthapuram, Kerala, 695522, India.
Mini, C.
Department of Postharvest Management, College of Agriculture, Vellayani, Kerala Agricultural University, Thiruvananthapuram, Kerala, 695522, India.
*Author to whom correspondence should be addressed.
Abstract
Being a good source of nutrients, viz., ascorbic acid, β-carotene, phenols, and antioxidants, pumpkin pulp (Cucurbita moschata) can be utilised as a functional ingredient in many food products by converting them into a more stable product like pumpkin powder. Hence the present study is focused on the production of freeze-dried pumpkin powder by two different methods (drying in petri plates with 5mm sample thickness and in 250 ml flask). The moisture content and water activity were reduced by 92.50% and 74.73%, respectively, compared to the fresh pumpkin pulp, indicating safe storage limits. Freeze-dried pumpkin powders exhibited a decrease of 25% ascorbic acid, 21.58% β-carotene, 39.39% reduction in total polyphenols and 72.98% in antioxidant content. The powder properties of the developed freeze-dried powders exhibited water activity of 0.4aw to 0.35aw bulk density of 0.15 to 0.12 g cm-3, and flow ability of 18.39° to 22.74°.
Keywords: Pumpkin, freeze-drying, nutritional properties, powder quality