Drying methods influence the physicochemical and functional properties of seed-used pumpkin

The effects of far-infrared radiation drying (FIRD), freeze drying (FD), vacuum drying (VD), and hot air drying (HAD) on appearance, physicochemical properties, antioxidant activities, antityrosinase capacity using B16F10 melanoma cell from seed-used pumpkins (hull-less pumpkin and hull pumpkin) were evaluated. Results suggested that hull-less pumpkin (HLP) dehydrated by FIRD provided the highest total polyphenols content (37.11 ± 1.05 mg GAE/ g DW) and the ability of scavenging free radicals. HPLC analysis exhibited that coumaric acid was predominant phenolic acid in pumpkin. The correlation analysis demonstrated that polyphenolic compounds were related to antioxidant capacity. HLP-FD possessed better colour, higher preservation of β-carotene, ascorbic acid and higher sugar contents compared with HLP-HAD. The highest antityrosinase activity was recorded in HLP-VD with a concentration of 37.16%. The melanin inhibition increased to 76.61%, and intracellular tyrosinase activity in B16F10 melanoma cells decreased to 88.63% at 800 μg/mL of polyphenol extract.