HIGROSCOPICIDADE DO EPICARPO, MESOCARPO E FARINHA DA AMÊNDOA DE BARU (Dipteryx alata Vogel)

Abstract

The present study deals with the pulp and almond of Baru (Dipteryx alata Vog.) fruits, which is part of the legume family, and it is inserted in the Cerrado biome. It is used by the local population as food and also for profit purposes such as wood, medicinal, industrial and landscape. The objective of this study was to determine the pulp and almond hygroscopicity of baru fruits in different air conditions and to adjust different mathematical models to the experimental data, as well as to obtain isosteric desorption heat values in function of the equilibrium water content of the product. The fruits were harvested and separated according to integrity, discarding those that present degraded parts, soon after they were sanitized and then they went through a process of rinsing. After the sanitization step the fruits were soaked in water at 30 °C for 18 hours, this step is necessary because of the mesocarp (pulp) hardness which was scraped with a knife after this softening period. The almonds were extracted from the interior of the woody endocarp using an equipment called coconut baru breaking machine produced exclusively by the company Metal Mix. For conducting the experiment, the water contents were obtained by drying the epircarpus, mesocarp and almonds in a forced ventilation oven, maintained at a temperature of 45 ° C. The reduction of the water content during the drying was accompanied by the gravimetric method, with weighing sequences until the desired water content was reached from 0.3737 to 0.8903 (decimal). The sorption isotherms of the epicarp, pulp and almond of the baru fruits were determined using the indirect static method while the water activity (aw) was determined by means of the Hygropalm Model Aw1 equipment. For each water content, three samples of approximately 20 g were used, which were placed individually in the equipment container and packaged in B.O.D. regulated at 10, 20, 30 and 40øC. According to the results it was conclude that: The water content of hygroscopic equilibrium of the baru epicarp is proportional to the water activity and reduces with the temperature increase for a same value of equilibrium water content. The Sigma Copace model is the one that best represents the baru epicarp hygroscopicity. The isosteric seed heat of the baru epicarp increases with the decrease of the equilibrium water content, requiring a greater amount of energy to remove the water. Among the models analyzed to the experimental data, it was verified that the model that best represented the experiment was the Sigma Copace model with mean error values estimated SE (1.396), and a chi-square χ2 (1.949), coefficient of determination of R² (98.10), respectively P% (5.350). The model Copace was another model that presented results close to the Sigma Copace model, with mean error values estimated SE (1.450), and a chi-square χ2 (2.102), determination coefficient of R² (97.95), respectively P% (5,505), but these small differences may prove to be biased and lead to error. Therefore, all the models tested presented a satisfactory performance in relation to the hygroscopic equilibrium water contents for the baru mesocarp samples, although the Sabbah model did not fit properly. The reduction in water content provides an increase in the energy required to remove the water from the baru mesocarp. The water content of the hygroscopic balance of the baru almond flour was directly proportional to the water activity and decreased with the temperature increase, for a same value of water activity. The Chung-Pfost model was the one that best represented the baru almond flour hygroscopicity by have the highest determination coefficient and the lowest values of mean relative and estimated errors and the Chi-square test.