EVALUATION of DRYING CHARACTERISTICS of PINEAPPLE IN the PRODUCTION of PINEAPPLE POWDER

The drying behaviour of osmosed and fresh pineapple, and the development of pineapple powder for use as dry food ingredient were investigated in this study. It was found that by osmotic dehydration alone 30 to 40% of the water content of pineapples could be removed in a day. the effects of temperature and sample thickness were evaluated when drying was carried out with air under controlled conditions. A mass transfer model, based on Fick's law of diffusion as applied to thin slab, was used to determine the effective diffusivity by using the experimental data where the shrinkage in sample thickness due to loss of water was taken into account. A power law equation was used to correlate the shrinkage in thickness with the moisture content of the sample. the effective diffusivity was found to be in the order of 10⁻¹⁰ m²/S. the activation energy for pineapple, which was estimated by using Arrhenius equation, was found to be 35.5 kJ/mol. For the production of pineapple powder, hygroscopicity and caking are considered to be the main problems. Chemical treatment with magnesium stearate was found useful at a concentration of 1% by weight.