Aproveitamento de resíduos do processamento semi-seco do café para a produção de compostos de valor agregado

Abstract

Coffee is one of the most cultivated products worldwide. The semi-dry processing generated significant amounts of coffee pulp and coffee wastewater. The objective of this study was to evaluate the feasibility of ethanol and volatile compounds production by fermentation of these residues, testing eight different yeast strains. Batch fermentation studies were performed in 100 mL, employing ground coffee pulp mixed with coffee wastewater. The strain Hanseniaspora uvarum UFLA CAF76 provided the best fermentation performance; hence it was selected to evaluate different culture medium compositions and the inoculum size for improving the fermentation performance. The best results were obtained with the follow conditions: 12% w/v of coffee pulp, 1 g/L of yeast extract and 0.3 g/L of inoculum size. Using these conditions was carried out a fermentation in 1 L of culture medium, achieving higher ethanol yield, ethanol productivity and conversion efficiency with values of 0.48 g/g, 0.55 g/L h and 94.81% respectively. Moreover, twenty-one volatile compounds corresponding to higher alcohols, acetates, terpenes, aldehydes and volatile acids were identified in the fermentation with H. uvarum UFLA CAF76. Such results indicated that coffee residues have excellent potential as culture medium for value-added compounds production, with this process would be attempted simultaneously conserving environment and improving the economic return to coffee producer farmers. Furthermore, H. uvarum UFLA CAF76 demonstrated high fermentative capacity using these coffee residues, thus it is an interesting yeast for further studies.