Natural fermentation with delayed inoculation of the yeast Torulaspora delbrueckii: Impact on the chemical composition and sensory profile of natural coffee.

Abstract

All coffee production stages occur in a microbiome, which is generally composed of bacteria, yeasts, and filamentous fungi. The use of starter cultures in post-harvest processing stages is an interesting alternative, since they promote faster removal of mucilage and incorporation of compounds that improve sensory quality, which can result in diverse sensory attributes for the beverage. This study was therefore developed with the objective of evaluating the effect of the following processing procedures on the chemical and sensory characteristics of the coffee beverage: first, fermentation of coffee fruit of the yellow Catucaí variety of Coffea arabica with indigenous microorganisms, followed by inoculation of the starter culture Torulaspora delbrueckii CCMA 0684 during the drying stage. The fruit was divided into two lots, which were differentiated by a natural fermentation process before drying began. The starter culture was inoculated on the coffee at different times during the drying process: at 0 h, 24 h, 48 h, or 72 h after drying began. The sensory attributes, the volatile compound composition of the roasted beans, the organic acid profile, the bioactive compounds, and the fatty acid profile of the green coffee beans were analyzed. The fatty acid and bioactive compound content showed little variation among treatments. Analysis of volatile compounds and organic acids and evaluation of sensory attributes made it possible to distinguish the two treatments. We conclude that natural fermentation of coffee fruit improve the chemical and sensory quality of the coffee beverage. The effect of natural fermentation may be before inoculation of the starter cultures or even during drying.