Modeling and Optimization of the Blanching and Freeze-Drying Process of Cantaloupe Slices (Cucumis melo L.) Based on Bioactive Components and Antioxidant Activity

Abstract

Cantaloupes (Cucumis melo L.) were blanched and freeze-dried under various conditions. Single-factor and two-factor experiments were conducted to determine the optimal processing conditions for achieving the best physicochemical properties, including polyphenols, flavonoids, ascorbic acid, antioxidant activity, and L∗. Two Box–Behnken design experiments, utilizing the response surface methodology (RSM), were employed to optimize both the blanching and drying processes. Blanching temperature (60°C–100°C), blanching time (2–10 min), slice thickness (0.2–1.2 cm), freezing time (24–72 h), freeze-drying time (15–45 h), and vacuum drying time (12–18 h) were investigated as independent variables. The results showed that polyphenol variation during blanching followed a linear model. However, the variations in flavonoids, ascorbic acid, antioxidant activity, and L∗ during blanching followed a quadratic model. This model was also found to be highly suitable for describing the changes in polyphenol, ascorbic acid, and moisture content during the drying process. The RSM identified the optimal conditions for producing freeze-dried cantaloupe slices, with blanching at 82.42°C for 4.83 min and a slice thickness of 1 cm. The proposed drying conditions include a freezing time of 43.12 h, a freeze-drying time of 26.74 h, and a vacuum drying time of 14.79 h, resulting in a total polyphenol content of 8.89 mgGAE/gDW, a total flavonoid content of 1.13 mgQE/gDW, and a moisture content of approximately 5%. The findings of this study provide a foundation for developing an optimized freeze-dried cantaloupe production process that ensures high product quality while minimizing operational costs.