Volatile, Microbial, and Sensory Profiles and Consumer Acceptance of Coffee Cascara Kombuchas

Abstract

Given the substantial world coffee production, tons of coffee fruit cascara rich in bioactive compounds are discarded annually. Using this by-product to produce potentially healthy and acceptable foods is a sustainable practice that aggregates value to coffee production and may help improve people’s lives. This study aimed to elaborate kombuchas from coffee cascara tea, evaluate their microbial profile, and monitor the changes in the volatile profile during fermentation, together with sensory attributes and acceptance by consumers from Rio de Janeiro (n = 113). Arabica coffee cascaras from Brazil and Nicaragua were used to make infusions, to which black tea kombucha, a Symbiotic Culture of Bacteria and Yeasts (SCOBY), and sucrose were added. Fermentation of plain black tea kombucha was also monitored for comparison. The volatile profile was analyzed after 0, 3, 6, and 9 days of fermentation via headspace solid phase microextraction GC-MS. A total of 81 compounds were identified considering all beverages, 59 in coffee cascara kombuchas and 59 in the black tea kombucha, with 37 common compounds for both. An increase mainly in acids and esters occurred during fermentation. Despite the similarity to black tea kombucha, some aldehydes, esters, alcohols, and ketones in coffee cascara kombucha were not identified in black tea kombucha. Potential impact compounds in CC were linalool, decanal, nonanal, octanal, dodecanal, ethanol, 2-ethylhexanol, ethyl acetate, ethyl butyrate, ethyl acetate, β-damascenone, γ-nonalactone, linalool oxide, phenylethyl alcohol, geranyl acetone, phenylacetaldehyde, isoamyl alcohol, acetic acid, octanoic acid, isovaleric acid, ethyl isobutyrate, ethyl hexanoate, and limonene. The mean acceptance scores for cascara kombuchas varied between 5.7 ± 0.53 and 7.4 ± 0.53 on a nine-point hedonic scale, with coffee cascara from three-day Nicaragua kombucha showing the highest score, associated with sweetness and berry, honey, woody, and herbal aromas and flavors. The present results indicate that coffee cascara is a promising by-product for elaboration of fermented beverages, exhibiting exotic and singular fingerprinting that can be explored for applications in the food industry.

Volatilome, Microbial, and Sensory Profiles of Coffee Leaf and Coffee Leaf-Toasted Maté Kombuchas

“…Figures 1 and 2 characterize the microbial community of the SCOBY and the final kombuchas CL K and CL-TM K (d9). The SCOBY composition was similar to that which was reported by the same authors for coffee cascara kombucha [35], with slight differences in microorganism strains and percentages in the CL and CL-TM kombuchas. All samples were found to contain two bacterial phyla, Proteobacteria and Firmicutes, according to the data analysis of the 16S rRNA gene sequence (Figure 1).…”

“…As also observed in coffee cascara kombucha, Enterobacteria were identified in CL K and CL-TM K, but in a lower percentage than in black tea kombuchas [35]. Enterobacteria are among commonly isolated microbial groups from spontaneous food fermentations, including kombucha fermentation [29,47,49].…”

“…Pediococ pentosaceus was confidently chosen to ferment tilapia surimi, resulting in the producti In CL K, characterized for the first time, K. rhaeticus comprised more than 70% of CL K microorganisms and about 90% of CL-TM K microorganisms contained in the liquid and solid cultures. In addition to a high percentage of K. rhaeticus (70-90%), K. europaeus (7-22%), K. intermedius (0.3%), and Gluconacetobacter entanii (0.5%) were identified in CL and CL-TM K. K. europaeus and K. intermedius have previously been identified in black tea kombuchas [29,53,54] and in coffee cascara kombucha [35]. According to Yao et al [55], K. europaeus and K.rhaeticus are positively associated with acid production in kombucha flavor.…”

“…The final average sucrose content in all kombuchas tended to decrease (37% in CL and 32.7% in CL-TM, from d0 to d9). Fermentation also decreased the soluble solids concentration, probably because of the decrease in the sucrose concentration in the culture medium over time [35,46]. At the beginning of the kombucha fermentation process, yeast produces invertase, which cleaves the disaccharide sucrose to its monosaccharide components: glucose, and fructose [44].…”

“…Staphylococcus carnosus and Staphylococcus xylosus were identified in BT K, CL K, and CL-TM K. It has also been in coffee cascara kombuchas [35]. They are found in several fermented food products and are recognized as non-infective, contributing to acidic and buttery characteristics [61].…”