Pós obtidos da polpa de pequi (Caryocar brasilense Camb.) liofilizada: higroscopicidade e microestrutura

Abstract

Food powders from the freeze-dried pequi pulp were developed in this work. These food powders were made with the addition of alcohol (ethanol and isopropyl alcohol) at concentrations of 0%, 5% and 10% and sugars (sucrose and fructose) at concentrations of 0%, 5% and 10% and its stability for the carotenoids retention and water adsorption during storage was evaluated. The carotenoid content was evaluated by measures of the water activity variation of the powders as related with time when put in controlled relative humidity environments. Isotherms obtained at 25 oC related with the equilibrium water activity of the product with the environment relative humidity were ploted and the Oswin model was the one which gave the best adjustment. Microstructural analyses by photonic microscopy and scanning electron microscopy of the freeze-dried pequi powders were done to visualize the powders crystallinity degree. Also, powders adhesiveness obtained from different treatments were measured. The results showed that the powders hygroscopicity presented characteristic differences. Sucrose and ethanol combination the one was which presented less variation of water activity, crystalline structures, lower adhesiveness values and reasonable carotenoids retention. Treatments with fructose and isopropyl alcohol yielded typically amorphous powders with the occurrence of the caking phenomenon.