Drying kinetics of uvaia pulp by-product
Brazil has a huge variety of fruit species with great potential of exploitation, such as uvaia (Eugenia pyriformis), an unconventional fruit, native from Brazilian Atlantic Forest. The fruits are commercialized in whole or processed form. When processed, many solid waste are generated. Generally, these by-products are just simply disposed in common waste, used as fertilizers or used to animal feed. However, the by-products might contain compounds that can still be interesting to human nutrition, such as fibers and bioactive compounds. The aim of this study was to evaluate different drying conditions of the solid waste obtained from uvaia pulp processing, using one of the most simple method of drying (hot air drying) in order to obtain a powder to be used in processed products for human nutrition. The by-product was dried in conventional cabin oven, with 0,4 m/s air velocity. Three temperatures: 40°C, 60°C and 80°C and two different conditions prior to drying process were used: with centrifugation (C) (2900 rpm, 5 min) and without centrifugation (NC), totalizing 6 different treatments. The by-product was dried in thin layers in perforated trays. Five different mathematical models were used to simulate the drying curves: Page, Lewis, Henderson and Pabis, Logarithmic and Wang and Singh. The equilibrium moisture was reached between 330 min (80°C/C) and 1100 min (40°C/NC). The models that best fit the uvaia by-product conventional drying were the Logarithimic and Page, with R² above 0,9989. Wang and Singh model, on the other hand, was the one that worst fitted the drying curves, with R² between 0,959 (80°C cent) and 0,9924 (40°C). Generally, Page, Lewis, Henderson and Pabis and Logarithmic models presented good predictions for uvaia by-product drying.