Optimizing novel drying process for Carissa carandas pulp: process parameters, drying kinetics, and thin-layer drying model validation

Foam-mat drying is widely used for fruit pulps; however, limited studies have systematically integrated process optimization, drying kinetics, and functional powder properties for underutilized fruits such as Carissa carandas. This study aimed to optimize foam-mat drying of C. carandas pulp to produce high-quality powder. Different levels of methyl cellulose, xanthan gum, and gum tragacanth, and whipping time were evaluated using Taguchi’s orthogonal array design. Optimized foams were dried at varying temperatures (45–90 °C) and thicknesses (5 and 10 mm). According to Taguchi’s optimization, the best-performing treatments methyl cellulose (0.4%), xanthan gum (0.3%), and gum tragacanth (0.1%), and whipping time (20 min) yielded lower foam density (0.172 g/cm3), higher foam expansion (550%), better foam stability (100%), lower moisture content (7.00%), and bulk density (0.192 g/cm3). The effective moisture diffusivity ranged from 3.93 × 10−1 to 2.50 × 10−9 m2/s across all treatments, while activation energy values were 27.58 and 22.07 kJ/mol for 5 and 10 mm foams, respectively. Among the tested models, the Hasibuan & Daud and Midilli et al. models provided the best fit for drying curves under various drying conditions. The study demonstrates the potential of foam-mat drying for producing stable and functional powder from C. carandas, contributing to improved utilization and quality assurance of underutilized fruit resources.