Physical-Chemical, Functional and Antioxidant Properties of Dehydrated Pumpkin Seeds: Effects of Ultrasound Time and Amplitude and Drying Temperature

This study aimed to investigate the influence of ultrasound pretreatment conditions and drying temperature on the quality parameters of pumpkin seeds. Various parameters, including drying time, water content, water activity, pH, total titratable acidity, proteins and lipid content, vitamin C, antioxidant activity and instrumental color, were evaluated. An experimental design (2(3) + 3 central points) was employed, with independent variables of ultrasound time (5, 10 and 15 min), ultrasound amplitude (30, 50 and 70%), and drying temperature (50, 60 and 70 degrees C). The water content and water activity showed lower values in samples submitted to higher ultrasound amplitudes and drying temperatures. The pH of the samples ranged from 6.90 to 7.04, and the total titratable acidity ranged from 1.83 to 2.39. Milder ultrasound experiments promoted more remarkable preservation of vitamin C than the others, presenting values ranging from 15.76 to 26.02 mg/100 g. The increase in drying air temperature caused more significant protein denaturation. The antioxidant potential was not affected by the application of the ultrasound process. Among the compounds evaluated in the phenolic profile, Procyanidin B2 and Gallic Acid components were predominantly present. The most abundant fatty acids in the samples were oleic and linoleic. The results provide insights into the optimization of the drying process and the quality attributes of pumpkin seeds. [GRAPHICS] .