DRYING BEHAVIOR ON DIFFERENT COFFEE FRUIT MATURATION STAGES

The maturation stage is directly related to the moisture content in foods; therefore, it influences drying processes of agroindustrial products. This work aimed to analyze the dehydration of coffee fruits (Coffea arabica L., Arara variety), cultivated at an altitude of 1050 m in the Cerrado Mineiro region. The fruits were manually selected and divided by the green, cane green, cherry, ripe cherry and raisin stages. In the tests, about 5 g of each sample were dried at 160°C for up to 120 min via infrared radiation (300 W ceramic emitter), in triplicate, comparing means by Tukey's test. From the analysis of the initial moisture w.b. for green (0.677a), cane green (0.671a), cherry (0.654a), ripe cherry (0.553b) and raisin (0.342c) fruits, all tests reached equilibrium moisture content (equal to zero) between 45 to 60 min, without significant differences. After 30 min of drying, the moisture w.b. of the fruits was 0.132a, 0.144a, 0.139a, 0.0809ab and 0.0356b, for green, cane green, cherry, ripe cherry and raisin, respectively. The maximum drying rates obtained were: green (94.4a mg/g.min), cane green (84.5ab mg/g.min), cherry (78.3b mg/g.min), ripe cherry (60.2c mg/g.min) and raisin (36.4d mg/g.min). According to the moisture ratio calculation, the drying kinetics constant, estimated through a mathematical adjustment using the Lewis model, were: green (0.0515ab min-1, R2 = 0.971, RMSE = 0.0529), cane green (0.0483a min-1, R2 = 0.964, RMSE = 0.0595), cherry (0.0487a min-1, R2 = 0.968, RMSE = 0.0561), ripe cherry (0.0570ab min-1, R2 = 0.968, RMSE = 0.0550) and raisin (0.0753b min-1, R2 = 0.972, RMSE = 0.0237). Then, it is noted that the greater the degree of maturation of the coffee fruits, the lower are the initial moisture and the drying rates, and the higher the drying constants tends to be, which indicates faster dehydration kinetics and water loss behavior.