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

Kombucha is a fermented beverage traditionally made from the leaves of Camelia sinensis. The market has drastically expanded recently, and the beverage has become more elaborated with new, healthy food materials and flavors. Pruning and harvesting during coffee production may generate tons of coffee leaves that are discarded although they contain substantial amounts of bioactive compounds, including those found in maté tea and coffee seeds. This study characterized the changes in volatilome, microbial, and sensory profiles of pure and blended arabica coffee leaf tea kombuchas between 3–9 days of fermentation. Acceptance was also evaluated by consumers from Rio de Janeiro (n = 103). Kombuchas (K) were prepared using black tea kombucha starter (BTKS) (10%), sucrose (10%), a symbiotic culture of Bacteria and Yeasts (SCOBY) (2.5%), and a pure coffee leaf infusion (CL) or a 50:50 blend with toasted maté infusion (CL-TM) at 2.5%. The RATA test was chosen for sensory profile characterization. One hundred volatile organic compounds were identified when all infusions and kombucha samples were considered. The potential impact compounds identified in CL K and CL-TM K were: methyl salicylate, benzaldehyde, hexanal, nonanal, pentadecanal, phenylethyl-alcohol, cedrol, 3,5-octadien-2-one, β-damascenone, α-ionone, β-ionone, acetic acid, caproic acid, octanoic acid, nonanoic acid, decanoic acid, isovaleric acid, linalool, (S)-dihydroactinidiolide, isoamyl alcohol, ethyl hexanoate, and geranyl acetone. Aroma and flavor descriptors with higher intensities in CL K included fruity, peach, sweet, and herbal, while CL-TM K included additional toasted mate notes. The highest mean acceptance score was given to CL-TM K and CL K on day 3 (6.6 and 6.4, respectively, on a nine-point scale). Arabica coffee leaf can be a co-product with similar fingerprinting to maté and black tea, which can be explored for the elaboration of potentially healthy fermented beverages in food industries.


Introduction
According to the Food and Agriculture Organization (FAO), sustainable food and agriculture is one in which food is nutritious and accessible to all and where natural resources are managed in a way that sustains ecosystem functions to meet present and future human needs [1].The Sustainable Development Agenda for 2030 adopted by United Foods 2024, 13, 484 4 of 30

Sensory Tests
The Ethical Committee of the Clementino Fraga Filho University Hospital at the Federal University of Rio de Janeiro (UFRJ) approved this study (# 4.513.606).The subjects, including students, teachers, visitors, and employees at the UFRJ Health Sciences and Technology Centers living in different areas of Rio de Janeiro provided written consent after being thoroughly informed.The eligible criteria for this study included habitual consumers of kombucha or sparkling beverages, such as sparkling water, ciders, and soft drinks.Individuals who had a positive COVID-19 diagnosis and experienced loss of taste and/or smell were excluded from the study, as were individuals with any other conditions that could affect sensory evaluation.A total of 103 participants took part in the Acceptance, Purchasing Intent, and Rate All That Apply (RATA) tests after exclusions.
Consumer assessors performed the tests on individual benches in the UFRJ Food and Dietetics Lab according to Sales et al. [35].

Consumer Acceptance and Purchase Intent
The assessors used a nine-point hedonic scale (ranging from one, which means extremely disliked, to nine, which means extremely liked) to evaluate the infusions.This was followed by a five-point purchase intent scale (ranging from one, which means certainly would not buy, to five, which means certainly would buy) [36].To calculate the Acceptability Index (AI) the following equation was used: AI = (X × 100)/N where X = Average score given by assessors and N = Highest score given by assessors.An AI equal to or greater than 70% was considered satisfactory [36].

Rate All That Apply (RATA)
The assessors were provided with a pre-prepared checklist of 34 sensory descriptors related to appearance, aroma, flavor, and mouthfeel.These descriptors were identified in a preliminary session by a trained panel of nine experts (aged  with a minimum of 200 h of experience in evaluating different food products and 30 h of experience in evaluating fermented beverages and infusions.The panelists were asked to generate their individual descriptors using a modified grid method [37].Afterward, they agreed on the best descriptors for fully describing the samples and the evaluation methods [38].The sensory descriptors used in the study were organized by alphabetical order as follows: burnt, fermented, fruity, green leaf, herbal, peach, rosé wine, sweet, toasted leaf, white wine (for odor); acidic/sour, bitter, and sweet (for taste); acetic/vinegar, alcoholic, apple vinegar, fruit syrup, fruity, toasted leaf, green apple, green coffee, herbal, peach, white wine, and brewer's yeast (for flavor); astringency, sparkling, fizzy, full-bodied, refreshing, and watery (for mouthfeel); and clear, brown, and opaque/matte (for appearance).To determine whether assessors perceived the varying intensities in the aroma, taste, and flavor descriptors of the kombucha samples, assessors were asked to score the descriptor based on their intensity using RATA scores (1 = low intensity, 2 = medium intensity, and 3 = high intensity).

Statistical Analysis
Data from physicochemical analyses are presented as mean ± standard deviation.Oneway ANOVA, followed by the Tukey test, was performed to identify significant differences (GraphPad Prism, Version 8.4.2,Informer Technologies, Los Angeles, CA, USA).
Statistical analyses of VOC data was performed by Principal Component Analysis (PCA) using individual peak areas as variables (R version 4.2.2,RStudio team 2022, Boston, MA, USA).Data pretreatment included normalization and scaling, which are required processes for data that present wide-scale differences, as is the case for volatiles.
For sensory tests, statistical analyses were conducted using the XLSTAT software, version 2023.1.1 (Addinsoft, Paris, France).ANOVA followed by the Tukey test was performed for acceptance (fixed factors: fermentation time and maté addition; random factor: consumers; and interaction between fermentation time and maté addition) and purchase intent tests results.For RATA descriptors, ANOVA, followed by Fisher's test and correspondence analysis based on chi-squared distances, was performed to achieve a sensory map of the samples [39].The test of independence between rows and columns was carried out at 5% significance.Cluster analysis (agglomerative hierarchical clustering using Euclidean distance for the Ward method) was also applied [40,41].Differences were considered significant when p ≤ 0.05.

Physicochemical Parameters
Table 1 presents the pH, total acidity, soluble solids, and sucrose values for all evaluated kombuchas.In CL K, the total acidity increased up to d9, and the pH decreased from 3.8/3.9 to 3.4.These values are within the ranges observed in the literature for kombuchas [22,42] and are caused by the fermentation process that forms several organic acids, which are mainly acetic, glucuronic, lactic, and citric acids, and the monosaccharides glucose and fructose [43,44].The addition of TM to CL made the fermentation process slower; therefore, the pH decreased mildly from d0 to d9, which is in agreement with the literature [45].
The pH values are within the kombucha pH range considered safe for human consumption (2.5 to 4.2) [31].Kombucha pH values below 2.5 have a high concentration of acetic acid, posing a risk to consumers' health.Likewise, pH values above 4.2 may compromise the beverage's microbiological safety [22].
Also, the kombucha pH has been shown by Ulusoy and Tamer [45] to stabilize due to the buffer effect caused by the organic acids and carbon dioxide formed during fermentation.According to the authors, the resulting aqueous solution of carbon dioxide dissociates and produces the amphiprotic hydrocarbonate anion (HCO 3 − ), which quickly Foods 2024, 13, 484 6 of 30 reacts with hydrogen ions (H + ) from organic acids, preventing further changes in the (H + ) concentration and contributing to the buffering character of the system.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].

Microbial Taxonomy
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).Proteobacteria was the overwhelmingly dominant phylum, with a percentage exceeding 90%, particularly in CL K and CL-TM K.This result is consistent with previous studies evaluating kombucha beverages' microbial profile [47][48][49].
Komagataeibacter, the most efficient bacterial cellulose producer [50], was the most abundant genus found in both the liquid and biofilm of all kombuchas, which is consistent with previous studies characterizing kombucha cultures [51].Only Komagataeibacter rhaeticus was identified in the starter culture, which accounts for about 40% of the total number of bacteria.This bacterium is known to be one of the most abundant members among kombucha fermenting agents [29,51].In kombucha, Komagateibacter genera are positively correlated with the presence of furfural and benzaldehyde, among other volatile compounds, and less correlated with acetic acid and octanoic acid [52].Data are expressed as mean ± standard deviation (n = 3); different superscript letters on the same column for the same beverage indicate significant difference (at p< 0.05) by ANOVA followed by the Tukey test; CL: coffee leaf tea; CL-TM: blend of coffee leaf tea and toasted maté tea.
The pH values are within the kombucha pH range considered safe for human consumption (2.5 to 4.2) [31].Kombucha pH values below 2.5 have a high concentration of acetic acid, posing a risk to consumers' health.Likewise, pH values above 4.2 may compromise the beverage's microbiological safety [22].
Also, the kombucha pH has been shown by Ulusoy and Tamer [45] to stabilize due to the buffer effect caused by the organic acids and carbon dioxide formed during fermentation.According to the authors, the resulting aqueous solution of carbon dioxide dissociates and produces the amphiprotic hydrocarbonate anion (HCO3 − ), which quickly reacts with hydrogen ions (H + ) from organic acids, preventing further changes in the (H + ) concentration and contributing to the buffering character of the system.
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].

Microbial Taxonomy
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).Proteobacteria was the overwhelmingly dominant phylum, with a percentage exceeding 90%, particularly in CL K and CL-TM K.This result is consistent with previous studies evaluating kombucha beverages' microbial profile [47][48][49].Komagataeibacter, the most efficient bacterial cellulose producer [50], was the m abundant genus found in both the liquid and biofilm of all kombuchas, which consistent with previous studies characterizing kombucha cultures [51].O Komagataeibacter rhaeticus was identified in the starter culture, which accounts for abo 40% of the total number of bacteria.This bacterium is known to be one of the m abundant members among kombucha fermenting agents [29,51].In kombuc Komagateibacter genera are positively correlated with the presence of furfural a benzaldehyde, among other volatile compounds, and less correlated with acetic acid a octanoic acid [52].
In CL K, characterized for the first time, K. rhaeticus comprised more than 70% of K microorganisms and about 90% of CL-TM K microorganisms contained in the liqu and solid cultures.In addition to a high percentage of K. rhaeticus (70-90%), K. europa (7-22%), K. intermedius (0.3%), and Gluconacetobacter entanii (0.5%) were identified in and CL-TM K. K. europaeus and K. intermedius have previously been identified in black kombuchas [29,53,54] and in coffee cascara kombucha [35].According to Yao et al. [55] europaeus and K.rhaeticus are positively associated with acid production in kombuc flavor.
The Gluconacetobacter genus has been detected in black tea kombuchas [29,49], well as in other fermented matrices [56] and kombuchas [57].This genus possess valua characteristics that can be combined with yeast strains for glucuronic acid product [58].
The Gluconacetobacter genus has been detected in black tea kombuchas [29,49], as well as in other fermented matrices [56] and kombuchas [57].This genus possess valuable characteristics that can be combined with yeast strains for glucuronic acid production [58].
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].
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].Pantoea septica was an additional Enterobacteriaceae strain identified in the starter kombucha [63].The Pantoea spp.genus was previously identified in grape cultivars for wine production and was positively correlated with straight-chain fatty alcohols, aromatic aldehydes, and terpenes in wine [64].
Pichia strains were previously identified as the main yeast genera in kombuchas [47,49,54].Pichia strains identified in CL and CL-TM kombuchas were Pichia fermentans, Pichia barkeri, and Pichia dianae, which are different from coffee cascara kombucha, in which the strains Pichia fermentans and Pichia kluyveri were identified [35].
Brettanomyces bruxellensis was the most common yeast identified in black tea kombucha [29,51,64] and in coffee cascara kombucha [35].Ester production during the fermentation is performed by the esterases present in Brettanomyces spp., which are responsible for the formation of ethyl esters, such as ethyl acetate and ethyl lactate, along with the hydrolysis of acetate esters, such as isoamyl acetate and phenethyl acetate, although this strain can also produce negative descriptors in fermentation products [65].In kombucha, Brettanomyces bruxelensis can contribute to alcohols and acids production, such as isoamyl alcohol and phenylehtyl alcohol [66] and is positively associated with the acetic acid formation in kombucha [55].
The percentage of Saccharomyces sp. was similar to that observed by Landis et al. [51] but was lower than coffee cascara kombucha [35].These genera and strains have been previously identified in kombuchas [47,49,55].Saccharomyces sp. is the major yeast genus involved in producing alcoholic beverages [67].Saccharomyces sp.strains have been previously identified in kombuchas [47,49,55].During fermentation, Saccharomyces cerevisiae (0.4-0.5%) presented a higher abundance in CL-TM K.In kombucha, this strain is correlated with ethanol [53,56].Another Saccharomyces strain identified was Saccharomyces paradoxus.This strain can produce high concentrations of hexanol, isoamyl alcohol, 2-phenylethyl ethanol, and ethyl acetate, among other volatile compounds, in wine [68].

Volatile Organic Compounds
Figure 3 presents the relative peak areas of volatile organic compounds (VOCs) (grouped by classes) in infusions and kombuchas made from CL, TM, and CL-TM.We also evaluated the VOCs from BT K starter culture, given that all kombucha beverages contained 10% of it.Although the area does not directly reflect the concentration of the compound, it serves an indicator of its relative abundance and, together with the total areas of the VOCs, provides the volatile profile, which is useful for comparison purposes [14].The potential impact of the compounds will be presented later in this section.
The highest peak areas in BT K starter were from acids, alcohols, and esters due to its advanced fermentation stage.Generally, the infusions tended to present higher area percentages of aldehydes, ketones, monoterpene-alcohols, and furans compared to kombuchas, while the kombuchas presented more acids, esters, and phenols due to the fermentation process [71].The substantial content of alcohols at d0 of fermentation in both kombuchas is derived from CL and TM raw materials and the starter culture [72,73].
For acids, the peak areas tended to increase with fermentation.Volatile acids are produced during alcoholic and acetic fermentation by the symbiosis between acetic acid bacteria and yeasts in SCOBY [73].The starter culture contributes greatly to the percentage and number of acids found in kombuchas [73].The high peak area of monoterpene alcohols could be explained by the free odor-producing forms of monoterpene alcohols, given the presence of glycosidically bound monoterpene alcohols in tea.Another possibility is the release of some aroma constituents when the non-volatile materials from tea leaves were fermented [74].
Fermentation products result from several complex and changeable enzymatic and/or chemical reactions involving volatile and nonvolatile precursors.These chemical changes result in the development of aroma and flavor.While BT, CL, TM, and CL-TM infusions can be characterized as having herbal/green leaf and woody aroma and flavor [14], kombucha production develops richer fruity and sometimes flowery aromas and flavors [75].Common metabolic pathways include those of carbohydrates, amino acids, fatty acids, and other The highest peak areas in BT K starter were from acids, alcohols, and esters due t advanced fermentation stage.Generally, the infusions tended to present higher a percentages of aldehydes, ketones, monoterpene-alcohols, and furans compared kombuchas, while the kombuchas presented more acids, esters, and phenols due to fermentation process [71].The substantial content of alcohols at d0 of fermentatio both kombuchas is derived from CL and TM raw materials and the starter culture [72 For acids, the peak areas tended to increase with fermentation.Volatile acids produced during alcoholic and acetic fermentation by the symbiosis between acetic bacteria and yeasts in SCOBY [73].The starter culture contributes greatly to percentage and number of acids found in kombuchas [73].The high peak area monoterpene alcohols could be explained by the free odor-producing forms monoterpene alcohols, given the presence of glycosidically bound monoterpene alco in tea.Another possibility is the release of some aroma constituents when non-volatile materials from tea leaves were fermented [74].
Fermentation products result from several complex and changeable enzym and/or chemical reactions involving volatile and nonvolatile precursors.These chem changes result in the development of aroma and flavor.While BT, CL, TM, and CLinfusions can be characterized as having herbal/green leaf and woody aroma and fla [14], kombucha production develops richer fruity and sometimes flowery aromas flavors [75].Common metabolic pathways include those of carbohydrates, amino ac fatty acids, and other lipidic components, among other classes.These pathways inte and intertwine to shape the unique flavor of foods [76].
The VOCs identified in the BT K starter and the CL, TM, and CL-TM infusions kombuchas are presented in Table 2.A total of 100 VOCs were identified, considering beverages, among them 23 esters, 19 aldehydes, 13 alcohols, 12 ketones, n monoterpenes, eight acids, five monoterpenes alcohols, five furans, two phenols, The VOCs identified in the BT K starter and the CL, TM, and CL-TM infusions and kombuchas are presented in Table 2.A total of 100 VOCs were identified, considering all beverages, among them 23 esters, 19 aldehydes, 13 alcohols, 12 ketones, nine monoterpenes, eight acids, five monoterpenes alcohols, five furans, two phenols, one pyrrol, and one heterocyclic aromatic compound.In the infusions, 37 VOCs were identified in CL, 48 in TM, and 67 in CL-TM.
When kombuchas were obtained, an increase in the number of VOCs was observed, from 37 to 75 in CL, with 24 derived from the BT K starter and 13 formed during fermentation.Of these newly formed compounds, 54% were esters and 23% were aldehydes.In CL-TM, the number of identified compounds increased from 67 to 90 after fermentation.Of these compounds, 20 were from the BTK starter, and seven were formed during fermentation, with 100% being esters.A similar increase in the number of VOCs was reported for coffee cascara kombucha [35].
In CL-TM K, the aldehyde 2,4-heptadienal is a marker compound in green and toasted maté [85,102].The formation of this VOC is favored by some steps in the maté processing such as scorching and drying, where the material is subjected to heat treatment [86].According to Mei et al. [87], 2,4-heptadienal is an impact compound in coffee leaf, although we did not identify it in CL infusion or CL K.
Regarding alcohols, 2-methyl-1-butanol, identified only in CL K samples, was identified in a green coffee spirit [106].Ethanol, identified in all kombucha samples, can impact the aromatic profile of kombucha [72].Additional alcohol identified was isoamyl alcohol, one of the most important sensory-active higher alcohols for beer aroma [104].Regarding acids, nonanoic acid is an odor active compound in coffee leaf tea [13] and was identified in CL K and CL-TM K. Acetic acid is the main acid responsible for kombucha sourness [72,73].Decanoic and octanoic acid were identified in all CL K and CL-TM K.They are reported as odor-active compounds in sparkling wine [71].
In kombuchas, ethyl acetate and methyl salicylate were identified in all CL Ks and CL-TM Ks; methyl salicylate is an odor-active compound in coffee leaf tea [87], Pu-erh tea [81], and oolong tea [107] and was previously identified in green maté [103].Ethyl acetate imparted apple and banana traits to wine [108], while ethyl decanoate and ethyl octanoate have been reported as abundant compounds in ciders [109]; ethyl isobutyrate and ethyl hexanoate have been reported as impact compounds in sparkling wine [71]; ethyl phenylacetate is one of the important esters in wine aroma compounds formed during alcoholic fermentation [108]; and ethyl laurate was correlated with positive aroma compounds in beer [110].
The only furan identified in all infusions and kombucha samples was dihydroactinidiolide.This VOC is viewed as critical in determining the aroma characteristics of black tea [96] and Pu-erh tea [81].It has been previously identified in coffee leaf tea [14] and green maté [85].This VOC can be generated by photo-oxidation of β-carotene under UV light [96].The presence of the phenols 4-ethylguiacol and 4-ethylphenol in BT K, CL K, and CL-TM K is probably due to the fermentative process by yeasts from the genus Brettanomyces through conversion of hydroxycinnamic acids [112,113].

Acceptance Test
The consumer assessors' main characteristics are presented in Table 3.After exclusions, a total of 103 assessors participated in the sensory assessment.The mean acceptance scores for CL K d3, d6, and d9 were 6.4, 5.9, and 5.4, respectively (Figure 4).Considering that in our previous study [14], blending with toasted maté tea increased the acceptance of CL infusions, we chose to blend CL and TM, aiming to increase the acceptability of CL-K.Acceptance of CL-TM K d3, d6, and d9 were 6.6, 6.2, and 5.9, respectively (Figure 4).Therefore, the highest mean scores were given to CL-TM K d3 and CL K d3, with 75% and 77%, of the scores, respectively, between six and nine.When scoring the samples, the assessors could comment on them if they wished.The most cited descriptors were 'sweet' for CL K and CL-TM K samples on d3 and d6 and 'taste of toasted maté' for CL-TM K.
Additional descriptors cited by assessors for CL K and CL-TM K were soft drink, peach, and peach syrup and bitter (consumers often tend to confuse acidity and bitterness sensations).scoring the samples, the assessors could comment on them if they wished.The most cited descriptors were 'sweet' for CL K and CL-TM K samples on d3 and d6 and 'taste of toasted maté' for CL-TM K.Additional descriptors cited by assessors for CL K and CL-TM K were soft drink, peach, and peach syrup and bitter (consumers often tend to confuse acidity and bitterness sensations).The preference for higher sweetness was caused by the need to balance the acidity caused by the increased number and abundance of the organic acids during fermentation.The preference of Brazilians for sweeter foods and the higher soluble solids in d3 content were also likely responsible for this result.
According to Meilgaard et al. [41], for a sample to be considered "well-accepted," it must obtain a 70% Acceptance Index (AI) or higher.Only the two most-accepted samples The preference for higher sweetness was caused by the need to balance the acidity caused by the increased number and abundance of the organic acids during fermentation.The preference of Brazilians for sweeter foods and the higher soluble solids in d3 content were also likely responsible for this result.
According to Meilgaard et al. [41], for a sample to be considered "well-accepted," it must obtain a 70% Acceptance Index (AI) or higher.Only the two most-accepted samples had higher AI, while the AI for d6 was 67%.The higher acidity was the main reason for the low score given on d9 (AI = 61%, on average).However, in countries where food is less sweet, like in Europe and perhaps in the U.S., d9 might have been better accepted, given that sugar consumption in these countries has decreased considerably over the last years [114,115].As usual, the purchase intent results were associated with those from the acceptance test (Figure 4A).
The high acceptance mean for CL-TM K may be explained by food pairing.The "food pairing hypothesis" states that two ingredients that share chemical compounds are more likely to taste (and smell) good together [116].In the present study, the volatile composition of CL and CL-TM infusions and kombuchas were similar (Table 2).Such similarity has also been observed for infusions in our previous study [14] in which the addition of toasted maté tea increased consumers' acceptance of coffee leaf tea.These two plants also share many non-volatile compounds, including the type and content of polyphenols and methylxanthines [28,117].
Making kombucha from coffee leaf infusions increased its acceptability, as compared to data from DePaula et al. [14] using the same raw materials.The referred study obtained 6.1 as a mean score for coffee leaf tea and 6.3 when a blend with 50% toasted maté was tested.No study using coffee leaf tea as a substrate for kombucha production was found for comparison with the present results.However, a study from the South of Brazil by Dartora et al. [118] conducted a sensory analysis of black tea, green tea, and green maté kombucha prepared with 5% (w/v) sugar, 0.5% (w/v) green maté and a SCOBY composed mainly by Brettanomyces bruxellensis and Komagaeitabacter rhaeticus as the major yeast and bacteria, respectively.Green maté kombucha presented a higher acceptance mean score (6.2) than black tea (5.8) or green tea (5.7) kombuchas.Assessors also expressed good feelings and sensations with emojis for green maté, while for black and green tea kombucha, the emojis were used to express negative feelings.It is worth noting that green maté is largely consumed in the South region of Brazil [118].
In the study conducted by Ulusoy and Tamer [45] in Turkey, the sensory acceptance of kombuchas made from new substrates such as black carrot, cherry laurel, blackthorn, and red raspberry and prepared with 6% w/v of sugar and a similar SCOBY, was evaluated using a nine-point hedonic scale.The beverages fermented for shorter periods (3 and 5 days) received scores between six and eight, while those fermented for 10 and 12 days received scores below five.The authors state that products with ratings below the five-point limit value are unlikely to be commercially successful.Moreover, studies conducted in Brazil and Tunisia have shown that assessors enjoyed herbal and grape kombuchas after 6 days of fermentation, with average acceptance scores ranging from five to seven.[119,120].
It is worth mentioning that the young age assessors were naturally selected by their will for participating in the study.The type of people willing to participate in a study that offers no reward other than the beverage itself indicates the inclination to consume the product.The study findings suggest that young adults are potential consumers of pure and blended CL K with a low fermentation period.In the questionnaire, it was clear that those who frequently consumed soda, a sparkling sweet beverage, were likely to attribute higher scores to kombuchas fermented for 3 days only (p < 0.0001), the samples with the highest amount of sucrose (Table 1).It is possible that adding CO 2 to the beverage will increase acceptance due to the increased resemblance to soda.Considering that the Brazilian consumers show preferences for sweeter beverages, especially among young consumers, d9 samples received low mean acceptance and purchase intent scores.Kombucha is a new beverage in Brazil, and understanding the consumers' and non-consumers' sensory perception toward the product brings essential information for the market to launch new products more accurately and assertively [118].
It is worth mentioning that while commercial kombuchas generally receive additives to increase flavor intensity and variety [121], in the present study, the kombuchas were naturally flavored, that is, with no additions of fruits, herbs, or spices to flavor them.

Rate All That Apply (RATA)
A RATA test was performed to identify changes during the fermentation of CL K (Figure 5) and CL-TM K (Figure 6).The fermentation time caused differences in the intensity of the sensory descriptors (p < 0.0001), while the presence of toasted maté in coffee leaf kombucha did not cause statistical differences.
It is worth mentioning that the young age assessors were naturally selected by their will for participating in the study.The type of people willing to participate in a study that offers no reward other than the beverage itself indicates the inclination to consume the product.The study findings suggest that young adults are potential consumers of pure and blended CL K with a low fermentation period.In the questionnaire, it was clear that those who frequently consumed soda, a sparkling sweet beverage, were likely to attribute higher scores to kombuchas fermented for 3 days only (p < 0.0001), the samples with the highest amount of sucrose (Table 1).It is possible that adding CO2 to the beverage will increase acceptance due to the increased resemblance to soda.Considering that the Brazilian consumers show preferences for sweeter beverages, especially among young consumers, d9 samples received low mean acceptance and purchase intent scores.Kombucha is a new beverage in Brazil, and understanding the consumers' and non-consumers' sensory perception toward the product brings essential information for the market to launch new products more accurately and assertively [118].
It is worth mentioning that while commercial kombuchas generally receive additives to increase flavor intensity and variety [121], in the present study, the kombuchas were naturally flavored, that is, with no additions of fruits, herbs, or spices to flavor them.

Rate All That Apply (RATA)
A RATA test was performed to identify changes during the fermentation of CL K (Figure 5) and CL-TM K (Figure 6).The fermentation time caused differences in the intensity of the sensory descriptors (p < 0.0001), while the presence of toasted maté in coffee leaf kombucha did not cause statistical differences.On d3, CL K presented higher intensities for herbal and sweet odors; sweet taste; fruity, herbal, and peach flavors; and clear appearance (Figure 5).This was also observed by Steger et al. [13], who observed that fermented coffee leaf infusions tended to produce sweetish fruity notes, especially a peach-like aroma and flavor.As expected, due to the microbial activity during fermentation, on d6, while the herbal, fruity, and peach flavors and sweet odor and taste decreased, the intensity of the fermented odor increased together with an acidic/sour taste and acetic/vinegar and apple vinegar flavors.CL K d9 presented the low intensity mean mainly for sweet odor and taste and the highest intensity for acidic/sour and acetic/vinegar tastes, apple vinegar flavors, and a fizzy mouthfeel.On d3, CL K presented higher intensities for herbal and sweet odors; sweet taste; fruity, herbal, and peach flavors; and clear appearance (Figure 5).This was also observed by Steger et al. [13], who observed that fermented coffee leaf infusions tended to produce sweetish fruity notes, especially a peach-like aroma and flavor.As expected, due to the microbial activity during fermentation, on d6, while the herbal, fruity, and peach flavors and sweet odor and taste decreased, the intensity of the fermented odor increased together with an acidic/sour taste and acetic/vinegar and apple vinegar flavors.CL K d9 presented the low intensity mean mainly for sweet odor and taste and the highest intensity for acidic/sour and acetic/vinegar tastes, apple vinegar flavors, and a fizzy mouthfeel.
The descriptors with the highest intensity means attributed to CL-TM K d3 (Figure 6) were the following: herbal, toasted leaf, fruity and sweet aromas, sweet taste, toasted leaf, herbal flavor, and refreshing.Similar descriptors have been obtained for toasted maté in our previous study [14].Higher intensity mean for fermented aroma and an acidic/sour taste and an acetic/vinegar flavor were attributed to CL-TM K d6 and d9, while herbal and toasted leaf odors and sweet taste intensities decreased.CL-TM K also showed a higher frequency of herbal descriptors for aroma and flavor, as observed by DePaula et al. [14], for blended coffee leaf and toasted maté infusions.
Some specific aromas and flavors perceived in kombuchas by the assessors (peach, white, and rosé wine aromas and green coffee, fruit syrup, green apple, peach, and white wine flavors) were not identified in the infusions in our previous study using the same raw materials [14].This result ratifies the change in the sensory profiles and the increases in flavor complexities caused by fermentation by the SCOBY microorganisms.Higher The descriptors with the highest intensity means attributed to CL-TM K d3 (Figure 6) were the following: herbal, toasted leaf, fruity and sweet aromas, sweet taste, toasted leaf, herbal flavor, and refreshing.Similar descriptors have been obtained for toasted maté in our previous study [14].Higher intensity mean for fermented aroma and an acidic/sour taste and an acetic/vinegar flavor were attributed to CL-TM K d6 and d9, while herbal and toasted leaf odors and sweet taste intensities decreased.CL-TM K also showed a higher frequency of herbal descriptors for aroma and flavor, as observed by DePaula et al. [14], for blended coffee leaf and toasted maté infusions.Some specific aromas and flavors perceived in kombuchas by the assessors (peach, white, and rosé wine aromas and green coffee, fruit syrup, green apple, peach, and white wine flavors) were not identified in the infusions in our previous study using the same raw materials [14].This result ratifies the change in the sensory profiles and the increases in flavor complexities caused by fermentation by the SCOBY microorganisms.Higher intensities for sweet aromas and tastes on d3 and d6 can be attributed to high soluble solids contents.In comparison, higher intensity means that the acid/sour tastes on d9 are attributed to the higher organic acid concentration reflected in higher TA and lower pH values [121].
Correspondence Analysis (CA) was applied to the RATA descriptors to generate the sensory map shown in Figure 7A.The first and second dimensions of the map explained 73.86% and 12.84% of the experimental data variance, respectively, representing 86.70% of the total variance (p < 0.0001).It is possible to see similarities between CL K on d3 and d6, between CL K on d9 and between CL-TM K on d9 and CL-TM K on d3 and d6 because the same descriptors were used to best describe these samples.Figure 7B presents the main sensory descriptors reported for the individual samples in the RATA test by the assessors in association with the acceptance scores and classes of volatile compounds used as secondary variables.The first two dimensions explained 83.26% of the variability, with 65.80% of the variance explained by dimension 1 and 17.46% by dimension 2. The descriptors leading to higher acceptance rates were those used to describe the samples at days 3 and 6 of fermentation with a higher intensity mean (Figures 5 and 6), which are associated with fruity, sweet, and herbal descriptors.Although phenols can impart undesirable odors to wine [112], they seem not to impact kombucha aromas because their area in chromatograms was lower than ketones, monoterpenes, and monoterpenes alcohols (Figure 3).
It is worth noting that the distribution of chemical classes in Figure 7B only considered the number of volatile compounds in each chemical class, together with the descriptors obtained in the RATA test.It did not consider the chromatogram peak areas or the odor threshold of the compounds.Nevertheless, the distribution of the classes is reasonably similar to the odor and flavor descriptions in the literature, which can be revisited in Table 2.This type of distribution seems to work better when a food matrix has a high number of volatile compounds of a certain class, given that a small number of important potential impact compounds could be neglected [14].Table 4 contains the RATA and related aroma and flavor descriptors related with the volatile compounds identified.Table 4. RATA aroma and flavor descriptors for coffee leaf and coffee leaf-toasted maté kombuchas and the corresponding volatile compounds identified in the present study (from Table 2).

RATA and Related Aroma and Flavor Descriptors Corresponding Volatile Compounds References
Foods 2024, 13, x FOR PEER REVIEW 24 of 32 Table 4. RATA aroma and flavor descriptors for coffee leaf and coffee leaf-toasted maté kombuchas and the corresponding volatile compounds identified in the present study (from Table 2).

Final Considerations and Conclusions
In the present study, a total of 100 volatile organic compounds were identified after considering all infusions and kombucha samples: 36 in the black tea kombucha starter, 75 in coffee leaf kombuchas, and 90 in coffee-leaf-toasted maté kombuchas.Coffee leaf and

Sparkling wine
Hexanoic acid, octanoic acid, ethyl isobutyrate, ethyl hexanoate, isoamyl acetate [71] The principal component analysis associated the volatile compounds profile with-RATA aroma and flavor descriptors.The biplot obtained (Figure 8) highlights that the changes on the profile of these selected volatiles during the kombucha fermentation are in agreement with those observed in the sensory characteristics.The observed changes in sensory characteristics during kombucha fermentation align with the evolution of the profiles of the selected volatiles.Similar changes in the profiles of the selected volatiles were noted in both CL K and CL-TM K from d3 to d9, although differences were observed between the two, as also noted in the RATA test.The PCA biplot explains the higher intensity of fruit, sweet, herbal, and peach flavors on d3 (associated with 3,5-octadien-2-one, α-ionone, phenylacetaldehyde, phenylethyl alcohol, linalool, β-damascenone, safranal, and linalool) and the impact of microbial activity on d6 and d9 that promoted the highest intensity for acidic/sour taste and acetic/vinegar, apple vinegar flavors, and fizzy mouthfeel (linked with nonanal, octanoic acid, decanoic acid, ethyl hexanoate, ethyl octanoate, ethyl decanoate, β-damascenone, linalool, and isoamyl alcohol).Hexanoic acid, octanoic acid, ethyl isobutyrate, ethyl hexanoate, isoamyl acetate [71] The principal component analysis associated the volatile compounds profile withRATA aroma and flavor descriptors.The biplot obtained (Figure 8) highlights that the changes on the profile of these selected volatiles during the kombucha fermentation are in agreement with those observed in the sensory characteristics.The observed changes in sensory characteristics during kombucha fermentation align with the evolution of the profiles of the selected volatiles.Similar changes in the profiles of the selected volatiles were noted in both CL K and CL-TM K from d3 to d9, although differences were observed between the two, as also noted in the RATA test.The PCA biplot explains the higher intensity of fruit, sweet, herbal, and peach flavors on d3 (associated with 3,5-octadien-2-one, α-ionone, phenylacetaldehyde, phenylethyl alcohol, linalool, β-damascenone, safranal, and linalool) and the impact of microbial activity on d6 and d9 that promoted the highest intensity for acidic/sour taste and acetic/vinegar, apple vinegar flavors, and fizzy mouthfeel (linked with nonanal, octanoic acid, decanoic acid, ethyl hexanoate, ethyl octanoate, ethyl decanoate, β-damascenone, linalool, and isoamyl alcohol).4. Coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9).

Final Considerations and Conclusions
In the present study, a total of 100 volatile organic compounds were identified after considering all infusions and kombucha samples: 36 in the black tea kombucha starter, 75 in coffee leaf kombuchas, and 90 in coffee-leaf-toasted maté kombuchas.Coffee leaf and coffee-leaf-toasted maté kombuchas presented similar volatile profiles.Thirty potential  4. Coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9).
The microbial consortia (SCOBY) used in this study were represented mostly by the acetic acid bacteria and yeasts from the genera Komagateibacter and Pichia, respectively.Komagataeibacter rhaeticus and Saccharomyces cerevisiae were more abundant in coffee-leaftoasted mate kombuchas than in coffee leaf kombuchas, while the contrary was true of Pichia sp.These differences indicate that raw materials can change the initial SCOBY profile during fermentation.This result is ratified by differences observed between the microbial profile found in this study and the one found in coffee cascara kombucha using the same initial starter culture [35].More studies are needed to verify the contribution of each food matrix to the SCOBY profile, and the impact of these differences on the aroma, flavor, and bioactivity of the resulting kombuchas.
Coffee leaf kombuchas and coffee-leaf-toasted maté kombuchas, especially those containing higher sucrose content and lower acidity, were accepted by Rio de Janeiro consumers.With herbal, toasted leaves, fruity and sweet traits, and lower acidity, coffeetoasted maté leaf kombuchas were only slightly more accepted than coffee leaf kombuchas.The authors believe that toasting coffee leaves would have increased acceptance by these assessors given the chemical resemblance to toasted maté.The volatile composition of the beverages supported the sensory characterization of kombucha samples.
Most people who agreed to participate in the study (53%) were aged 18-24 years.These were also the people who most regularly consumed similar beverages to kombucha, like soda, sparkling water, and sparkling wine.It has been estimated that the young people in Latin and North America will shape the market for the next decades [134].Considering that they are looking for natural soft drinks that are perceived as promoting well-being and have a limited amount of added sugar, kombuchas and sparkling kombuchas prepared with pure or blended coffee leaf with other herbs or teas could be of great interest to them, given that these leaves are rich in bioactive compounds and have exerted health-functional properties in vitro [10], with limited amount of caffeine for those who are sensitive to its effect.
In conclusion, coffee leaf was shown to be a suitable raw material for producing aromatic, natural, and potentially healthy kombucha beverages.Given the fact that Brazil is responsible for one-third of the world's coffee production, the acceptance of coffee leaf kombucha by Brazilians opens a large perspective for the national coffee growers and food industry.Concomitantly, this is a way to reduce the environmental pollution caused by incorrect disposal after harvest season and the pruning of coffee trees, improving the coffee chain value and allowing sustainability to be aligned with the United Nations and FAO goals for 2030.Giving the numerous known health benefits of coffee consumption, the similar chemical composition of the leaf in many aspects, and the potential benefits of fermentation for increasing the bioaccessibility of polyphenols and other components of the beverage, the health effects of usual coffee leaf kombucha drinking should be evaluated in future studies.

Figure 1 .
Figure 1.Characterization of the bacterial composition of the black tea kombucha starter (BT K) and that of coffee leaf (CL K) and coffee-leaf-toasted maté (CL-TM K) kombucha consortia after 9 days of fermentation.

FoodsFigure 1 .
Figure 1.Characterization of the bacterial composition of the black tea kombucha starter (BT and that of coffee leaf (CL K) and coffee-leaf-toasted maté (CL-TM K) kombucha consortia afte days of fermentation.

Figure 2 .
Figure 2. Yeast composition of the black tea kombucha starter (BT K) and the coffee leaf (CL K) a coffee-leaf-toasted maté (CL-TM K) kombucha consortia after 9 days of fermentation.

Figure 2 .
Figure 2. Yeast composition of the black tea kombucha starter (BT K) and the coffee leaf (CL K) and coffee-leaf-toasted maté (CL-TM K) kombucha consortia after 9 days of fermentation.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Figure 7 .
Figure 7. Correspondence analysis (CA): bi-dimensional plot of the samples of coffee leaf (CL K) and coffee-toasted maté leaf (CL-TM K) kombuchas after 3, 6, and 9 days of fermentation (d3, d6, and d9) (A) and sensory descriptors attributed by consumer assessors (n = 103) through the RATA test, distributing volatile compounds and descriptors that make up the best acceptance of samples among consumers (B).Overall liking and the volatile compounds were considered to be supplementary variables.Note: O: odor; T: taste; F: flavor; M: mouthfeel; A: appearance.

Table 2 .
Volatile compounds identified in coffee leaf and coffee-toasted maté leaf kombuchas.

Table 3 .
Socio-economic profiles of the sensory tests assessors.

Table 3 .
Socio-economic profiles of the sensory tests assessors.

Table 4 .
RATA aroma and flavor descriptors for coffee leaf and coffee leaf-toasted maté kombuchas and the corresponding volatile compounds identified in the present study (from Table2).

Table 4 .
RATA aroma and flavor descriptors for coffee leaf and coffee leaf-toasted maté kombuchas and the corresponding volatile compounds identified in the present study (from Table2).

Table 4 .
RATA aroma and flavor descriptors for coffee leaf and coffee leaf-toasted maté kombuchas and the corresponding volatile compounds identified in the present study (from Table2).

Table 4 .
RATA aroma and flavor descriptors for coffee leaf and coffee leaf-toasted maté kombuchas and the corresponding volatile compounds identified in the present study (from Table2).

Table 4 .
RATA aroma and flavor descriptors for coffee leaf and coffee leaf-toasted maté kombuchas and the corresponding volatile compounds identified in the present study (from Table2).

Table 4 .
RATA aroma and flavor descriptors for coffee leaf and coffee leaf-toasted maté kombuchas and the corresponding volatile compounds identified in the present study (from Table2).