Uso de culturas iniciadoras na fermentação do café arábica (Coffea arabica) em biorreatores

Abstract

Coffee arrived in Brazil in the year 1727 and currently the country is considered the largest producer. This crop belongs to the Rubiaceae family, the genus Coffea, being the most cultivated C. arabica and C. canefora. This culture has aroused the interest of consumers looking for special classified drinks considered coffees with unique flavors and aromas. The formation of the characteristics of the drink occurs during the formation of the fruit and the plant as a whole. Therefore it is important to perform good agronomic practices to ensure product quality. Preprocessing methods such as natural, CD and wet can be used, with subsequent drying of the grains. During the fermentation of the fruit can be found microorganisms such as bacteria, yeast and fungi. Yeasts are of great importance and can be used as starter cultures because they produce pectinolytic enzymes, alcohols, acids and release sugars, improving the taste of the drink. Saccharomyces cerevisiae and Torulasporadelbrueckii, both derived from natural coffee fermentation, have high pectinolytic activity, excellent fermentative capacity and release desirable metabolic products in the final beverage. Depending on how the fermentation is done the characteristic of the drink also varies. As an example, would be the use of containers such as bioreactors to perform the fermentation process. This study aimed to inoculate Saccharomyces cerevisiae (CCMA 0543) and Torulasporadelbrueckii (CCMA 0684) in coffees in the Sul de Minas Gerais, Zona da Mata and Cerrado regions, both processed by cherry and pulped cherry in order to improve the quality of final drink. Inoculum viability was assessed by real time polymerase chain reaction (qPCR) and volatile and nonvolatile compounds were evaluated by gas chromatography coupled to mass spectrometer (GC-MS) and high performance liquid chromatography (HPLC) respectively, the sensory analysis of the treatments was also performed. S. cerevisiae was dominant during spontaneous fermentations and inoculated for both types of processing. T. delbrueckii showed similar population with and without inoculation. Glucose and fructose were consumed rapidly during fermentation. Malic and succinic acids were detected in the coffee fermentation process and when present contribute to the quality of the beverage, as they intensify the sweetness. The results of volatile compound analysis showed that each treatment correlated with different groups, the cherry coffee from locality 1 inoculated with S. cerevisiae correlated with furan, pyrrole and alcohol. However, cherry coffee from locality 2 and inoculated with T. delbruckii (CCMA0684) were correlated with pyrrole, furan, ester and acids. The coffees inoculated with T. delbruekii presented higher scores in relation to the control. In region 2, for example, cherry coffee increased by 5.75 points with inoculation use compared to treatment without starter culture. The use of S. cerevisiae influenced mainly the coffees processed by the cherry method, in region 3 the scores reached 83 points, while the control was 79.75. Among the evaluated regions, the use of starter cultures showed an increase in grade according to the results of the sensory analysis, being a recommended practice.