Drying behaviour and optimization of drying conditions of pineapple puree and slices using refractance window drying technology.

Refractance window drying technology can be used to produce high quality dried fruit products due to its excellent retention of heat sensitive nutrients, organoleptic properties and bioactive compounds. This study optimised conditions for drying of pineapple slices and puree using RWDT. i-optimal design in Design Expert software was used to generate temperature-thickness combinations in form of runs. The independent factors considered included drying temperature (70-90 °C) and thickness (2-3 mm), and the responses included drying time and vitamin C concentration. The optimum solutions generated for RW drying temperature and pulp thickness were 86.2 °C and 2.9 mm for puree and 78.9 °C and 2 mm for slices. The drying times for puree and slices were 58 and 96 min, respectively with corresponding vitamin C content of 64.88 and 46.83 mg/100 g. Drying kinetics of puree and slices were determined at optimal conditions. Drying was found to follow Modified Midilli et al. Model. Pineapple powder obtained using optimal RWD conditions had low water activity (0.41), high solubility (74.64%) and dehydration ratio (4.12). Pineapple reconstituted drinks were developed and evaluated for consumer preference. Acceptability was highest at 15% inclusion of pineapple powder. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-021-05302-2. © Association of Food Scientists & Technologists (India) 2021.