Optimization of spray-drying conditions using response surface methodology, physico-chemical characterization and shelf-life estimation of pineapple powder

Abstract

Response surface methodology (RSM) was used in this study to optimize spray drying process conditions for pineapple juice powder (PJP) production. Box–Behnken design (BBD) with three factorials and three levels was used for experimental design. The inlet air temperature (X₁), feed rate (X₂) (10–20 ml min⁻¹), and maltodextrin (10DE) content (X₃) (30–50% of TSS of pineapple juice) were the independent factors. Multiple regression was used to build the model and statistical analysis of variance (ANOVA) was performed to establish the significance of the data. Moisture content and powder yield were the response variables employed for analysis. Moisture content and yield both had R² values of 0.92 and 0.90, respectively. The response model, which had a lower p-value (0.05), produced results that were statistically significant for the experimental data. The optimization conditions of an inlet air temperature of 171 °C, feed rate of 14.57 ml min⁻¹, and maltodextrin content of 40.83% were achieved and used to provide 68.20 ± 0.22 powder yield and 5.27 ± 0.12 moisture content (w.b). Adsorption isotherm curves of the powder revealed the characteristics of a type III shape. The Guggenheim–Anderson–de Boer (GAB) and Iglesias & Chirife models were the best-fitted models to demonstrate the sorption isotherm behaviour of dried PJP powder. The accelerated storage studies of PJP was performed at temperatures 40, 50, 60 & 70 °C where ascorbic acid loss was taken as the marker of thermal degradation of the product. At 40 °C, the shelf life of pineapple powder was obtained as 12.35 days, whereas on increasing the storage temperature the shelf life of the powder decreased. Similarly, the shelf life of pineapple powder at 50, 60 & 70 °C was obtained as 6.11, 2.78, and 0.8 days, respectively, and the calculated activation energy was 19.534 kJ mol⁻¹.