Mathematical Modeling and Physicochemical Characterization of Foam-Mat Drying of Acerola (Malpighia emarginata) Pulp

This study aimed to evaluate the physical properties of foam produced with different additives and to mathematically model foam-mat drying at different temperatures. Foams were made with 500 g of acerola pulp and 4% additives (albumin, emustab, and neutral alloy), and density and stability data were obtained. With suitable density (0.14367 g cm^-3) and coalescence (0.0000 mL) values, emustab provided the best acerola pulp foam. Drying was performed at temperatures of 50, 55, 60, 65, and 70 °C, using emustab, and different mathematical models were fitted for each temperature. The fresh pulp and the dried powder were analyzed for water activity, moisture content, ash, pH, total titratable acidity, soluble solids content, reducing sugars, vitamin C, total carotenoids, and instrumental color. The logarithmic model showed the best fit for all temperatures, with increasing k-values (between 0.0021 and 0.0059 s^-1) and effective diffusion coefficient (between 2.570 × 10^-9 m² s^-1 and 5.060 × 10^-9 m² s^-1) with increasing temperature. Temperature directly impacts the effective moisture diffusion coefficient with an activation energy of 30.88 kJ mol^-1. The physicochemical properties of the foams varied significantly with increasing drying temperature. Among all the temperatures tested, 60 °C was the most appropriate to reduce changes in nutritional composition.