Optimization of Process Parameters for Foam-Mat Drying of Peaches
Peach (Prunus persica) is a highly perishable fruit with short shelf-life and susceptible to mechanical damage during harvest and post-harvest operations such as sorting, processing, packaging, and transport. Therefore, converting peaches into dehydrated products will not only reduce their post-harvest losses but also retain their nutritional and sensory qualities. The current study aimed at the optimization of process parameters of foam-mat drying for the production of peach powder from the peaches grown in Ontario, Canada. The operating parameters of foam-mat dryer such as temperatures (65°C, 70°C, and 75°C), foam thickness (3, 5, and 7 mm) and the concentration of foaming agents (soy and pea protein isolates (0.5% w/w, 1% w/w, and 1.5% w/w), were optimized using response surface methodology. The resulting peach powder obtained after drying was assessed for moisture, color, total phenols, antioxidant activity, microstructure, and thermal properties. It was observed that drying time increased with an increase in foam thickness and decreased with an increase in temperature and foaming agent concentrations. The optimum drying rate obtained for both proteins based foams was observed at 65°C. Physico-chemical analysis of peach powder showed significantly higher retention of bioactive components such as total phenols and antioxidants in foam mat dried peach powder containing PPI as the foaming agent. The differential scanning calorimetry thermogram for both protein isolates suggested a denaturation temperature of proteins was around 85°C. No significant difference was observed in the morphological structure of powders obtained by using both protein isolates as foaming agents.