Fermentation of coffee fruit with sequential inoculation of Lactiplantibacillus plantarum and Saccharomyces cerevisiae: effect on sensory attributes and chemical composition of the beans.

This study has innovative aspects related to the use of sequential inoculation technique in the coffee bean fermentation process: the inoculation of Lactiplantibacillus plantarum followed by Saccharomyces cerevisiae, in the fermentation of coffee fruit for the production of specialty natural coffees. The objective was to evaluate the effect of this technique and of the total fermentation time on the sensory attributes of the coffee beverage and on the organic acid profile, bioactive compounds, and fatty acid profile of the beans. The fermentation of coffee fruit with sequential inoculation resulted in greater acidity of the beverage and contributed to increases of up to 2 points in coffee fermented. The total fermentation time was directly related to the organic acid content, and the longer the total fermentation time was, the greater the organic acid content. The fatty acid content and bioactive compound content showed little variation among treatments.

Fermentation of coffee fruit with sequential inoculation of Lactiplantibacillus plantarum and Saccharomyces cerevisiae: Effects on volatile composition and sensory characteristics.

Mixed starter cultures of lactic acid bacteria and yeasts used in the production of fermented foods, including coffee, can improve the sensory quality and food safety. The objective of this study was to evaluate the effects of fermentation of coffee with inoculation of Lactiplantibacillus plantarum followed by Saccharomyces cerevisiae and the effects of fermentation time on the aroma and flavor of the coffee beverage and on the volatile composition of the roasted coffee beans. The coffee was fermented for 48 h or 96 h after inoculation of Lactiplantibacillus plantarum followed by inoculation of Saccharomyces cerevisiae or the respective controls. The aroma and flavor of the coffee beverage fermented with sequential inoculation showed complexity, with a predominance of fruity and fermented sensory notes. Forty-seven volatile compounds were identified. In addition, the sequentially inoculated coffees had greater formation of volatiles and led to greater perception of fruity and fermented flavor and aroma.

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

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.

Discharge of solubilized and Dectin-1-reactive ß-glucan from macrophage cells phagocytizing insoluble ß-glucan particles: involvement of reactive oxygen species (ROS)-driven degradation.

Phagocytes engulf pathogenic microbes, kill them and degrade their cellular macromolecules by hydrolytic enzymes in phagolysosomes. However, such enzymes are unable to degrade some microbial polysaccharides, and fate of such indigestible polysaccharides in phagocytes remains uncertain. Using the extracellular domain of Dectin-1 as ß-glucan-specific probes, we succeeded in detection of soluble and Dectin-1-reactive ß-glucan discharged from mouse RAW 264.7 and human THP-1 macrophage cell lines as well as mouse peritoneal macrophages, which had phagocytized insoluble ß-glucan particles. The RAW 264.7 cell culture-supernatant containing the discharged ß-glucan stimulated naïve RAW 264.7 cells, resulting in the induction of cytokine expression. Such discharge of Dectin-1-reactive ß-glucan from macrophage cells was inhibited by either NADPH oxidase inhibitors (apocynin and diphenylene iodonium) or radical scavengers (N-acetyl cysteine and MCI-186). Moreover, reactive oxygen species (ROS) produced by a Cu(2+)/ascorbic acid system solubilized insoluble ß-glucan particles in vitro, and a part of the solubilized ß-glucan was Dectin-1 reactive and biologically active in macrophage activation. The soluble and biologically active ß-glucan was degraded further during prolonged exposure to ROS. These results suggest that degraded but Dectin-1-reactive ß-glucan is discharged from macrophage cells phagocytizing insoluble ß-glucan particles and stimulates not only themselves again but also the other naïve phagocytes, leading to the effective elimination of infecting microbes and the ultimate breakdown and inactivation of metabolically resistant ß-glucan.