Characterization of Freeze-dried Pumpkin Powders: Powder Quality and Nutrient Stability

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°.