Secagem de pequi (Caryocar brasiliensis cambess) precedida de desidratação osmótica

Abstract

Pequi is a typical fruit of the Brazilian cerrado of great nutritional, gastronomic and economic importance to the region. Its use is not widespread around the country mainly to its high perishability. The aim of this study was to evaluate the drying of pulp pequis by two methods: natural convective drying and vacuum drying, both in an oven, preceded or not by osmotic dehydration (OD) in sucrose solution. Analysis of drying kinetic, water activity (aw) and shrinkage were made. First tests were performed at two sucrose concentrations of OD: 40 °Brix and 60 °Brix, with moisture and solids content in immersion measured up to 120 minutes. The effective diffusivity of water and solids was calculated according to Fick's second law. At characterization after the osmotic process was concluded that, according to Tukey's test, both concentrations have similar results to raw material, in terms of final water content, water loss, solids gain, aw and shrinkage, being chosen concentration of 40 °Brix in time of 120 minutes for the pre-treatment to drying. Fresh and osmotically dehydrated samples, which had an initial moisture content (wb) of 51.49% and 31.86%, respectively, were dried to 13% (wb). The drying was done at two ways: natural convection and vacuum, at two temperatures: 40 °C and 60 °C. The kinetics of drying was adjusted according to the model of Fick, Newton, Page, Henderson and Pabis. The settings of all models were satisfactory, and the Page had a higher R². Both the use of OD as increasing the temperature decreased the final drying time. The use of vacuum did not significantly alter the process time. Differences in aw and shrinkage between treatments were analyzed using the Tukey’s test, with no significant difference between treatments for aw, and shrinkage was greater at higher temperature and time of process.