CHANGES IN PHYSICOCHEMICAL PROPERTIES OF CATIGUÁ COFFEE AFTER FERMENTATION

The application of different fermentation processes to produce specialty coffees is a technique of interdisciplinary scientific-industrial interest, in which changes in the fruit composition can influence the final quality of the beverage. This work aimed to monitor physicochemical parameters in loco during the fermentation process of natural coffee (Coffea arabica L., Catiguá MG2 variety), cultivated at an altitude of 1048 m in the Cerrado Mineiro region. The tests were carried out in 200 L high-density-polyethylene canisters for a period of 60 h at room temperature, using spontaneous self-induced anaerobic fermentation in solid-state. The fruits were sorted in two groups: green and ripe cherry – G1 (apparent specific mass of 0.865a ±0.0222 g/cm3) and raisin with buoy – G2 (apparent specific mass of 0.740b ±0.0164 g/cm3); the statistical differences were analyzed using Tukey's test. Regarding the total soluble solids content, the G1 fruits changed from 17.3a ±1.59 to 14.7a ±2.51 °Brix, while G2 fruits changed from 20.2b ±1.97 to 15.8a ±3.34 °Brix. For pH values, both experiments obtained more acidic media after fermentation, either for G1 (5.27a ±0.149 to 4.44b ±0.0288) and G2 (5.24a ±0.151 to 4.55b ±0.0727) fruits. Regarding temperature analysis, G1 fruits changed from 20.9a ±0.247 to 23.3b ±0.152 °C, while G2 fruits changed from 20.4a ±0.555 to 26.6c ±0.817 °C. Thus, the occurrence of fermentation was identified through the reduction in total soluble solids and pH values and also by the increase in temperature, which indicates the exothermic conversion of sugars into organic and volatile acids. In addition, variations in total soluble solids content and temperature were more significant in the raisin and buoy fermentation, while the green and ripe cherry fermentation had a greater decrease in pH, with significant differences between the maturation stages analyzed.