Process optimization of spray drying conditions for custard apple (Annona squamosa L.) pulp powder using response surface methodology

Response Surface Methodology (RSM) was employed to optimize the spray-drying conditions for the production of custard apple (Annona squamosa L.) pulp powder using maltodextrin as a carrier agent. The pulp of the custard apple is highly perishable and contains numerous bioactive compounds that are heat sensitive. This complicates the production of a stable powder that retains its nutrients during conventional drying methods. The inlet and outlet air temperatures were identified as the most significant process factors affecting the physicochemical, nutritional and functional properties of the produced powder. Higher inlet temperature enhanced drying efficiency and augmented powder output; however, they also accelerated the degradation of ascorbic acid and exacerbated non-enzymatic browning. Higher outlet temperatures positively influenced functional attributes such as wettability, swelling capacity and water absorption capability. The developed RSM models exhibited a high degree of predictive accuracy (R² > 0.92), with experimental and anticipated values closely aligned, indicating their adequacy. Multi-response optimization identified the optimal drying conditions, with an inlet temperature of 175.2 °C and an outlet temperature of 90 °C. The custard apple powder exhibited low residual moisture, moderate hygroscopicity, substantial vitamin C retention, negligible browning and favorable immediate properties that facilitated reconstitution. The results indicate that optimal spray-drying conditions can produce high quality custard apple powder, suitable for use as a functional ingredient in ready-to-drink beverages, nutraceuticals and fortified foods.