TEMPERATURE AND pH MONITORING DURING THE COFFEE FERMENTATION PROCESS

Coffee pulp and mucilage serve as a substrate for the development of bacteria, yeasts and filamentous fungi, supplying them with sources of carbon and nitrogen. During coffee fermentation, microorganisms can be associated with the degradation of pectin and other carbohydrates, production of desirable volatile and non-volatile compounds, and positive and differentiated sensory characteristics. Therefore, in this study, the temperature and pH were monitored during the solid state (FES) and submerged fermentation process (with the addition of 30% of the volume of water) for 72 hours, of the natural coffee Paraiso variety located at 1090 meters altitude in the municipality of Patos de Minas, with these coffees fermented in 20-liter bioreactors. For this, the temperature and initial pH were evaluated in quintuplicate, presenting an average of (23.51°C±0.49) and (5.25±0.11) respectively. After 72 hours of fermentation, there was an increase in the average temperature of the fruit fermented in solid state and submerged state, (29.58 °C±1.03) and (32.00°C±1.53), respectively. It was also observed that there was a drop in the pH value after 72 hours for (4.11±0.06) FES cherry and (3.80±0.28) submerged cherry. This process was observed indirectly due to the exothermic behavior of the fermentation process due to the increase in temperature inside the bioreactor and reduction in the pH of the medium during the 72-hour fermentation process. The production of acids seen from the decline in pH observed in this study is related to the fermentation of sugars, such as glucose and fructose present in fruits, culminating in the generation of organic acids such as citric, malic, tartaric, acetic, lactic, phosphoric and succinct. Thus, it was observed that due to the fermentative processes, both in solid and submerged states, there was an increase in the internal temperatures of the bioreactors and a reduction in the pH of the fermented coffee.