ABSTRACT
For the first time, the dual effect of coffee cherry sanitization methods to control the microbial load in processing and the influence of fermentation time on coffee quality parameters was evaluated. Two assays were carried out by wet processing: I) Sanitization of the coffee cherry (ST1: Unclassified processed cherries; ST2: Classified and sanitized cherries with drinking water; ST3: Classified and sanitized cherries with a chemical agents and II) Fermentation times (FT1: 12 h; FT2: 24 h; FT3: 48 h; FT4: 72 h and FT5: 96 h). pH, temperature, and dissolved oxygen were monitored during fermentation. Counts of Lactic Acid Bacteria - LAB, mesophiles, and yeasts were carried out on the coffee mass before and after fermentation. Caffeine and chlorogenic acid contents were determined by HPLC-DAD and the sensory profile by methodology for specialty coffees (SCA). The main findings showed that: sanitization with Timsen® did not significantly influence the evolution of pH during fermentation (p > 0.05), but it can reduce to a small extent the action of LAB at the end of the process. It was observed that the temperature of the coffee mass tends to balance with the ambient temperature, with significant effects (p < 0.05) of sanitization (ST2 and ST3) on the stability of this variable during fermentation. Timsen® as a disinfectant affected microbial populations and improved the sensory profile in the cup. In prolonged coffee fermentations (FT3, FT4 and FT5), the pH of the coffee mass tended to stabilize after 36 h, regardless of the process time. Likewise, a correlation was evident between a higher microbial load correlated with better sensory profiles in FT4 and FT5. Neither the sanitization process nor the fermentation time significantly affected the caffeine and chlorogenic acid contents of the coffee, both in its green and roasted states. Consequently, the sanitization of cherry coffee with Timsen® and prolonged fermentation times favor the safety and coffee final quality in the cup.
ABSTRACT
RESUMEN Este trabajo presenta los resultados obtenidos a escala de laboratorio para el aprovechamiento de la pulpa de café (residuos) en el proceso de beneficio húmedo aplicando el concepto de biorrefinería. Los resultados mostraron que es posible tratar este residuo mediante procesos fermentativos y obtener bioetanol separado por medio de la destilación simple con un contenido de alcohol entre 3,85 % al 6,90 % por cada 250 ml de biomasa tratada en condiciones ambientales. Se observó en todos los ensayos que una variable importante es el tiempo de fermentación y la estructura inicial del residuo ya que esto influye sobre el rendimiento obtenido en términos del bioalcohol producido. Este trabajo forma parte de un estudio preliminar para la implementación del concepto de biorrefinería a los residuos generados en el beneficio húmedo del café. La búsqueda de alternativas que permitan el aprovechamiento de los residuos del café constituye una problemática actual. Estos residuos al no ser tratados, por lo general son vertidos a las fuentes hídricas y en ocasiones utilizados como enmiendas agrícolas en los cultivos, lo cual puede causar graves problemas de contaminación. Por este motivo es necesario realizar investigaciones en este campo que permitan su tratamiento o aprovechamiento integral.
ABSTRACT This work presents the results obtained at a laboratory scale for the use of coffee pulp (residues) in the wet milling process applying the concept of biorefinery. The results showed that it is possible to treat this residue through fermentative processes and obtain bioethanol through simple distillation with an alcohol content between 3.85% to 6.90% for each 250ml of biomass with a solid-liquid ratio of 4 to 1 to environmental conditions. It was observed in all the tests that the fermentation time and the initial structure of the residue are important variables since they influence the yield obtained in terms of produced alcohol. This work is part of a preliminary study for the implementation of the biorefinery concept to the residues generated in the wet coffee mill. The search of alternatives that allow the use of coffee residues is a current problem. These residues, when not treated, are generally dumped into water sources and sometimes used as agricultural amendments in crops, which can cause serious contamination problems. For this reason, it is necessary to carry out research in this field for its treatment or comprehensive use.