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Wet fermentation of Coffea canephora by lactic acid bacteria and yeasts using the self-induced anaerobic fermentation (SIAF) method enhances the coffee quality
Abstract
This work aimed to evaluate the impact of inoculation single and co-cultivation of LAB and yeasts during the wet process of Coffea canephora using the self-induced anaerobic fermentation method. Saccharomyces cerevisiae, Totulaspora delbrueckii delbrueckii, Leuconostoc mesenteroides, and Lactiplantibacillus plantarum were monitored during fermentation. L. mesenteroides was detected in high concentrations in the coffee fruits (8.54 log10 cells/mL) and remained until the end of fermentation. Lactic and acetic acids were the main acids produced during fermentation. After 36 h of fermentation, 75.39% of malic acid was consumed in the L. mesenteroides + S. cerevisiae (MC) fermentations. In roasted coffee, the caffeine concentration reached 3.29 higher than the green beans in MC fermentation. Specific volatile compounds were detected in inoculated fermentation and may contribute to the beverage quality. Coffee inoculated with Leuconostoc mesenteroides was classified as fine (80.0–89.0), while the other fermentations were classified as premium (70.0–79.0). L. mesenteroides inoculation showed the best sensory score, and the beverage was characterized by caramel, fruity, and spices notes. L. mesenteroides inoculated alone or in co-culture with S. cerevisiae are promising starter cultures to improve Conilon coffee quality and obtain beverages with differentiated sensory profiles.
... performance of lactic acid bacteria (LAB), as these microorganisms develop in low-oxygen environments and utilize available carbohydrates for fermentation. Studies indicated that higher concentrations of LAB in coffee fermentation using SIAF contributed to a reduction in fermentation time and produced organic compounds that enhance the final quality of the coffee [1,2]. Besides yeasts, some Lactiplantibacillus plantarum (L. ...
... Besides yeasts, some Lactiplantibacillus plantarum (L. plantarum) strains have been identified as promising starter cultures for coculture with yeasts and monoculture, as these species can impart red fruits, milk chocolate, citrus fruits, and wine aromas in coffee beverages [1,2]. ...
... The use of starter cultures in wet coffee fermentation, aiming to improve beverage quality and modify sensory profiles, was reported by Cassimiro et al. [2] in whole fruits of Coffee canephora. However, this study limits the understanding of the effects of starter cultures in other processing methods, such as in pulped coffee beans. ...
Volatile and nonvolatile compounds directly impact the quality of coffee beverages. This study demonstrated how chemical and sensory compounds were affected by three starter cultures (Saccharomyces cerevisiae, Torulaspora delbrueckii, and Lactiplantibacillus plantarum) inoculated separately and co-inoculation using the self-induced anaerobic fermentation (SIAF) method for pulped coffee.High-Performance Liquid Chromatography (HPLC) analyzed carbohydrates, bioactive compounds, and organic acids. Gas chromatography (GC‒MS) examined volatile compounds, monitored microbial composition by quantitative real-time PCR (qPCR), and performed sensory analysis using the cupping test. During fermentation, fructose was the predominant carbohydrate. Lactic acid concentrations were more expressive at the end of the process in the liquid fraction, with higher levels detected in the control (6.93 g·kg⁻¹). In all fermentations, the concentrations of chlorogenic acids and trigonelline decreased after the roasting process, while the levels of caffeine increased. Esters, such as methyl salicylate and 2-hydroxy benzoic acid ethyl ester, which contribute to the perception of fruity and caramelized notes, were formed during the fermentation process. The fermentation with S. cerevisiae and T. delbrueckii presented different descriptors from spontaneous fermentation, such as chocolate, nuts, and almonds. L. plantarum fermentation showed blackberry, spices, and nut/cocoa flavors. Fermentation using co-inoculation (S. cerevisiae and L. plantarum) produced coffees with unique aromas, including honey, brown pepper, nutmeg, and cinnamon. Therefore, wet coffee processed using the SIAF method, adding inoculum of yeasts and lactic acid bacteria, delivers a more complex and exquisite beverage.
... the fermentation method has contributed to the improvement of sensory profiles, becoming an alternative approach for increasing the quality of Canephora coffees (Agnoletti et al., 2022;Bravim et al., 2023;Cassimiro et al., 2023). ...
... Using selected bacteria and yeasts is an economically viable alternative to obtain coffees with different flavors and aromas. In addition, it contributes to greater standardization of the process, reduction of fermentation time, inhibition of the growth of undesirable microorganisms, and production of promising compounds for improving the quality of the beverage (da Prakash et al., 2022;Bravim et al., 2023;Cassimiro et al., 2023). ...
... M. guilliermondii combined with the SIAF method increased the coffee score by over three points, improved the production of desirable volatile compounds (2methylpyrazine, two-ethylpyrazine, furfuryl alcohol, and 5methylfurfural), enhanced the perception of sweetness and the sensory complexity of Conilon coffee. Leuconostoc mesenteroides resulted in a beverage with notes of caramel, fruits, and spices in wet-processed Conilon coffee subject to SIAF method (Bravim et al., 2023;Cassimiro et al., 2023;da Silva et al., 2021;do Rosário et al., 2023). ...
Recent investigations into the microbiota and fermentation of Coffea canephora fruits and beans have yielded limited advancements globally, highlighting a developing field of study. Consequently, this review seeks to consolidate existing literature through an analysis focusing on the microbiota and fermentation processes inherent in the postharvest processing of Canephora coffee. To this end, a comprehensive examination of the principal microorganisms inherent to this species, the application of starter cultures in fermentation, and the repercussions of fermentation on the chemical and sensory attributes of the beverage will be expounded. These investigations underscore the influence exerted by the fermentation process and the introduction of microorganism inoculation on Canephora coffees’ chemical composition and sensory characteristics. Fermentation emerges as a mechanism facilitating the modification of coffee flavor and aroma, thereby presenting avenues for innovative enhancements in producing distinct Canephora coffee beverages. Research to assess the microbiota of Canephora coffees from various origins has the potential to advance our understanding of the microbial ecology specific to this species. Such studies will play a crucial role in identifying pertinent starter cultures that could be used to produce high-quality coffees.
... When properly conducted, fermentation reduces the growth of undesirable microorganisms such as filamentous fungi, increases the number of volatile and non-volatile compounds, and improves the beverage score [4][5][6][7]. Recently, a fermentation method called self-induced anaerobiosis fermentation (SIAF) was proposed [8] and has obtained good results in Arabica and Canephora coffee [9][10][11][12][13][14]. In the SIAF method, coffee is fermented in closed bioreactors, in which oxygen is consumed, and CO 2 is gradually produced due to the metabolic activity of microorganisms. ...
... The application of starter cultures isolated from coffee has been explored and demonstrated improvements in beverage quality [4,5,19,21,22]. Recently, the use of starter cultures combined with the SIAF method has been proposed and has yielded promising results for Arabica and Canephora coffees [8,12,13]. In this study, the inoculation of the yeast M. guilliermondii using SIAF was evaluated for the first time, resulting in a significant improvement in the score of Canephora coffee. ...
... The production of alcohols by yeasts during fermentation favors the formation of esters via lipid and acetyl-CoA metabolism [24]. Compounds in this class are related to fruity and floral aromas [12]. Floral and vanilla aromas were perceived in Canephora coffee with yeast inoculation. ...
... The flavor-enhancing capabilities of "wild-type" LAB cultures in coffee fermentation have drawn attention due to the variety of aromas these strains can produce, including floral, fruity, and buttery notes [11]. Recent research on the co-culture of lactic yeast and lactic acid bacteria has been crucial in improving beverage quality and achieving coffees with distinct sensory profiles [12]. ...
... includes mannose, galactose, and arabinose, which further support LAB fermentation [47]. Additionally, studies [12,43] have demonstrated that employing LAB and yeast as starter cultures enhances coffee quality. Figure 4 presents a contour plot showing yeast viability under various combinations of components (X1, X2, and X3). ...
... includes mannose, galactose, and arabinose, which further support LAB fermentation [47]. Additionally, studies [12,43] have demonstrated that employing LAB and yeast as starter cultures enhances coffee quality. correlation is logical, as a larger population of lactic acid bacteria facilitates the production of lactic acid, leading to a decrease in the pH of the medium (coffee pulp and mucilage broth) to an optimal growth pH of 4.5. ...
Recent research has highlighted the effectiveness of starter inocula in fermentation processes. In this sense, this study examines the use of an inoculum composed of coffee pulp, mucilage broth, and microorganisms such as Saccharomyces cerevisiae, L. delbrueckii ssp. bulgaricus, and S. thermophilus in fermenting Castillo variety coffee. An inoculum was prepared, measuring variables such as the pH, acidity, °Brix, lactic acid bacteria, and yeast viability. Following optimization, the inoculum was evaluated in a fermentation process, evaluating the pH, °Brix, acidity, microbiological analysis, ochratoxin A, and cup quality post-drying and roasting. The findings demonstrated a significant reduction in the pH from 4.47 to 4.05 and in the °Brix from 15.8 to 8.45, indicating efficient organic acid production and sugar degradation. Acidity levels increased from 20.02 mg/g to 42.69 mg/g, while microbial viabilities remained above 107 CFUs/g, suggesting effective biomass production. The process effectively reduced the microbial load without detecting ochratoxin A. Sensory evaluations confirmed the enhanced cup quality, validating the positive impact of inoculum use in coffee fermentation. The results support the use of coffee pulp and mucilage broth as effective substrates for the growth of the evaluated microorganisms, and the application of starter cultures containing lactic acid bacteria and yeast can elevate the coffee to a specialty grade.
... Using an anaerobic system favours the metabolism of lactic acid bacteria and yeast, promoting the production of specific metabolites (Pereira et al., 2022). According to Cassimiro et al. (2023), anaerobic conditions increase the production of lactic acid, contributing to the acidic flavour of coffee. Furthermore, the absence of oxygen induces an alternative metabolic pathway that mainly results in the formation of CO 2 , ethanol, glycerol, acid pyruvic and succinic, volatile alcohols, and esters (Ferreira et al., 2023). ...
... Caffeine, trigonelline, and chlorogenic acids are examples of bioactive compounds responsible for functional characteristics such as coffee's antioxidant potential. These compounds may have their concentration altered due to fermentation with selected starter cultures, and correlate with the sensory profile contributing to the pigmentation, astringency, and bitterness of the coffee beverage (Cassimiro et al., 2023). As a result, several studies aiming at the use of starter cultures have been developed (Table 1), highlighting the importance of selecting microbial strains suitable for the process conditions and desired characteristics of the final product. ...
... The biotransformation of coffee through submerged fermentation is widely reported (Elhalis et al., 2021;Agnoletti et al., 2022;Cassimiro et al., 2023), and several beneficial effects for coffee quality are evidenced. In a study by Mahingsapun et al. (2022), where 24 types of Arabica coffee beans inoculated with different starter cultures were tested, wet fermentation promoted the production of specialty coffees with distinct sensory characteristics. ...
Fermentation has been studied to improve the chemical composition and sensory profile of coffee, of interest to the food industry and farmers seeking competitiveness in the international market. This study addresses the influence of biotransformation on the synthesis of flavour precursor compounds and correlates subsequent processes, such as roasting, and chemical mechanisms responsible for the formation of coffee's sensory profiles. The results indicate that coffee fermentation contributes to the formation of precursor metabolites of volatile compounds and the different fermentation techniques favour the production of high‐quality coffee. Bibliometrics analysis from 2012 to 2022 highlighted Brazil and China with a high number of research, scientific collaborations, and international cooperation, indicating a current trend in research focused on sensory modulation. Fermentation technologies point to a promising scenario with the possibility of producing coffee with previously defined sensory characteristics. This market is in full development and corroborates the growing pace of coffee consumption.
... When properly conducted, fermentation reduces the growth of undesirable microorganisms such as filamentous fungi, increases the number of volatile and non-volatile compounds, and improves the beverage score [4][5][6][7]. Recently, a fermentation method called self-induced anaerobiosis fermentation (SIAF) was proposed [8] and has obtained good results in Arabica and Canephora coffee [9][10][11][12][13][14]. In the SIAF method, coffee is fermented in closed bioreactors, in which oxygen is consumed, and CO 2 is gradually produced due to the metabolic activity of microorganisms. ...
... The application of starter cultures isolated from coffee has been explored and demonstrated improvements in beverage quality [4,5,19,21,22]. Recently, the use of starter cultures combined with the SIAF method has been proposed and has yielded promising results for Arabica and Canephora coffees [8,12,13]. In this study, the inoculation of the yeast M. guilliermondii using SIAF was evaluated for the first time, resulting in a significant improvement in the score of Canephora coffee. ...
... The production of alcohols by yeasts during fermentation favors the formation of esters via lipid and acetyl-CoA metabolism [24]. Compounds in this class are related to fruity and floral aromas [12]. Floral and vanilla aromas were perceived in Canephora coffee with yeast inoculation. ...
Specialty coffee has become increasingly consumed in recent years. The growth of the specialty coffee market has also led to a greater appreciation of the unique flavors and characteristics of different coffee species. Coffea arabica (Arabica coffee) and Coffea canephora (Canephora coffee, known internationally as Robusta) are the main species of most significant economic importance worldwide. This study aims to evaluate the use of Meyerozyma guilliermondii in the self-induced anaerobiosis fermentation (SIAF) of Coffea arabica and Coffea canephora. SIAF without inoculation (spontaneous fermentation) and with inoculation of yeast M. guilliermondii was conducted for five days in closed bioreactors. Volatiles and sensory analyses were performed in the roasted coffees. Twenty volatile compounds were identified in Arabica coffee and fifteen in Canephora coffee. The classes found were esters (7), pyrazines (7), ketones (4), alcohols (2), aldehydes (2), phenols (1), and pyrrole (1). Furfuryl alcohol was a significant compound for Arabica coffee, while 4-ethenyl-2-methoxyphenol was notable for Canephora coffee. M. guilliermondii increased significantly (p < 0.05) the score by over 3 points, improved the production of desirable volatile compounds (2-methylpyrazine, 2-ethylpyrazine, furfuryl alcohol, and 5-methylfurfural), enhanced the perception of sweetness and the sensory complexity of Canephora coffee. The SIAF method combined with M. guilliermondii can be a practical approach for improving the sensory quality of the Canephora coffee beverage. Spontaneous fermentation combined with the SIAF method resulted in an Arabica coffee beverage of good quality.
... Improving coffee flavor quality through fermentation with selected special microbiota and different processing methods has become very popular and effective. Species of yeastincluding Picha fermentans, P. kudriavzevii, Saccharomyces cerevisiae, and Candida parapsilosis-and bacteria-including Lactiplantibacillus plantarum, Leuconostoc mesenteroids, and Bacilus subtilis-have been used for coffee fermentation [7][8][9][10][11][12]. For example, coffee fermentation inoculation with L. mesenteroides improved the sensory score to 81, providing the coffee with dark chocolate, caramel, nutty, and spicy characteristics [7]. ...
... Species of yeastincluding Picha fermentans, P. kudriavzevii, Saccharomyces cerevisiae, and Candida parapsilosis-and bacteria-including Lactiplantibacillus plantarum, Leuconostoc mesenteroids, and Bacilus subtilis-have been used for coffee fermentation [7][8][9][10][11][12]. For example, coffee fermentation inoculation with L. mesenteroides improved the sensory score to 81, providing the coffee with dark chocolate, caramel, nutty, and spicy characteristics [7]. In addition, the cocultivation of L. mesenteroides with Leuconostoc plantarum led to a higher sensory score of 81.33 than that of a single inoculation with L. mesenteroides [7]. ...
... For example, coffee fermentation inoculation with L. mesenteroides improved the sensory score to 81, providing the coffee with dark chocolate, caramel, nutty, and spicy characteristics [7]. In addition, the cocultivation of L. mesenteroides with Leuconostoc plantarum led to a higher sensory score of 81.33 than that of a single inoculation with L. mesenteroides [7]. ...
Coffee fermentation is crucial for flavor and aroma, as microorganisms degrade mucilage and produce metabolites. This study aimed to provide a basis for understanding the impact of microorganisms on Coffea arabica from Yunnan, China, during washed processing. The microbial community structure and differentially changed metabolites (DCMs) of C. arabica beans during washed processing were analyzed. The results indicated that the top five predominant microorganisms at the genera level were Achromobacter, Tatumella, Weissella, Streptococcus, and Trichocoleus for bacteria and Cystofilobasidium, Hanseniaspora, Lachancea, Wickerhamomyces, and Aspergillus for fungi. Meanwhile, the relative content of 115 DCMs in 36 h samples decreased significantly, compared to non-fermentation coffee samples (VIP > 1, p < 0.05, FC < 0.65), and the relative content of 28 DCMs increased significantly (VIP > 1, p < 0.05, FC > 1.5). Furthermore, 17 DCMs showed a strong positive correlation with microorganisms, and 5 DCMs had a strong negative correlation (p < 0.05, |r| > 0.6). Therefore, the interaction and metabolic function of microbiota play a key role in the formation of coffee flavor, and these results help in clarifying the fermentation mechanisms of C. arabica and in controlling and improving the quality of coffee flavor.
... Regardless of the processing type, natural, pulped, or wet process, the Self-Induced Anaerobiosis Fermentation (SIAF) method has been shown to enhance the quality of the beverage (da Mota et al., 2022;Pereira et al., 2022;Schwan et al., 2023). SIAF is a fermentation method in which microbial metabolism gradually produces the anaerobiosis using the remaining O 2 for its metabolic reactions, releasing CO 2 and volatile and non-volatile compounds (Cassimiro et al., 2023). Furthermore, this method positively impacts the fermentative performance of lactic acid bacteria (LAB) and yeasts during coffee processing (da Mota et al., 2020;Pereira et al., 2022). ...
... Candida parapsilosis showed an initial population of 3.23 log 10 cells/g in natural coffee and 2.68 log 10 cells/g in pulped coffee, both in SIAF control. The highest populations reported by the yeasts S. cerevisiae and T. delbrueckii may have inhibited the growth of C. parapsilosis by competing for nutrients (Cassimiro et al., 2023;Martinez et al., 2017;Silva et al., 2008). Considering the population growth of microorganisms present in coffee, sugars are considered the primary source of energy for these microorganisms (Kim et al., 2022) and essential in the coffee fermentation process. ...
Our objective was to monitor the main enzymes of coffee germinal metabolism and chemical composition during Self-Induced Anaerobiosis Fermentation (SIAF) with yeasts (Saccharomyces cerevisiae (CCMA0543), Candida parapsilosis (CCMA0544) and Torulospora delbrueckii (CCMA0684)) evaluating their relationship with seed germination. The starter cultures were assessed by qPCR. The organic acids were analyzed by liquid chromatography. Catalase (CAT), Esterase (EST), Alcohol dehydrogenase (ADH), and Isocitrate Lyase (ICL) enzyme activity was confirmed by the presence of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-Page) gel bands. The formation of a white halo confirmed the activity of the enzyme endo-β-mannanase, and its quantification was performed using the diameter of the halo of both the samples and the standard curve. At the end of the fermentation process, S. cerevisiae and T. delbrueckii presented the highest populations (>7 log10 cells/g). Succinic
acids (average −1.11 g/kg) were consumed during SIAF. Lactic acid increased after 180 h in coffees fermented by the SIAF method (average 3.57 g/kg). CAT and EST showed high activity in the conventional process. ADH activity was detected in both processes after 180 h of the SIAF method. Yeast inoculation during the SIAF method increased the activity of ICL and showed more intense activity in the first 96 h of fermentation, especially the pulped coffee. Endo-β-mannanase activity was intense during conventional coffee processing (9.89–10.99 pmol/min/g). Natural processing tends to preserve a higher percentage of viable seeds. Therefore, the processing and fermentation methods impact seed quality differently.
... If the total score of the cupping analysis is in the range of 70.00-79.00, it is considered premium [20]. C. arabica is the main cultivated species of coffee in Yunnan province, China, which is a well-known cultivation base of C. arabica in the world [21]. ...
... Coffee fermentation duration is often uncertain; a complete coffee fermentation needs 12-36 h [5]. In addition, the study on the fermentation method has become an effective way to improve coffee quality [31,32] and special microbial fermentation also been used as a starter to improve coffee flavor [20,33]. ...
The washed process is one of the traditional post-harvest processes of coffee beans, which include selective harvesting, flotation, pulping, submerged fermentation underwater, washing, and drying operations. During the washed processing, fermentation underwater can remove coffee mucilage and change metabolites by microorganisms. Therefore, coffee fermentation is a key factor influencing coffee’s flavor. To compare the influence of fermentation duration in an open environment of Coffea arabica in 48 h during the washed processing on the coffee’s flavor, the sensory characteristics of the coffee at different fermentation durations were evaluated using the Specialty Coffee Association of America (SCAA) cupping protocol. Moreover, ultra performance liquid chromatography–triple quadrupole mass spectrometry (UHPLC–MS/MS) and gas chromatography–mass spectrometry (GC–MS) were combined to analyze and compare the chemical compounds of coffee samples from fermentation durations of 24 h (W24) and 36 h (W36) during the washed processing method. The results showed that W36 had the highest total cupping score with 77.25 in all different fermentation duration coffee samples, and 2567 non-volatile compounds (nVCs) and 176 volatile compounds (VCs) were detected in W36 and W24 during the washed processing method. Furthermore, 43 differentially changed non-volatile compounds (DCnVCs) and 22 differentially changed volatile compounds (DCVCs) were detected in W36 vs. W24. Therefore, suitable fermentation duration in an open environment is beneficial to coffee flavor, judging by chemical compound changes. For the washed primary processing of C. arabica from Yunnan, China, 36 h fermentation was the suitable fermentation duration in an open environment, which presented potential value as the reference for washed coffee processing in the food industry.
... This method ensures anaerobiosis by gradual O 2 consumption and CO 2 production. Consequently, the lactic acid bacteria and yeast populations increase, producing metabolites that favor the flavor and aroma of coffee beverages [6][7][8]. ...
Variation in fermentation time may be an essential alternative to provide coffee beverages with different and unique sensory profiles. This work investigated the microbiological, chemical, and sensory changes in coffees submitted to different fermentation durations (0, 24, 48, 72, and 96 h). Self-induced anaerobiosis fermentation (SIAF) was used, and two treatments were performed: spontaneous fermentation and inoculation with S. cerevisiae CCMA0543. Microbiological analyses were performed, and the permanence of the inoculum was monitored. Chromatography (sugars, organic acids, and volatile compounds) was analyzed, and sensory analysis (temporal dominance of sensations - TDS) was performed. A total of 228 isolates were identified during spontaneous fermentation. The dominant bacteria and yeasts were Leuconostoc mesenteroides, Lactiplantibacillus plantarum, Staphylococcus warneri, Bacillus sp., Torulaspora delbrueckii, Hanseniaspora uvarum, and Meyerozyma caribbica. High concentrations of citric (18.67 mg.g− 1) and succinic (5.04 mg.g− 1) acids were detected at 96 h in SIAF fermentation. One hundred twenty-one volatile compounds were detected, but 22 were detected only in inoculated coffees. In spontaneous fermentation, 48 h of fermentation showed woody notes, while 72 h showed chestnuts. However, in the inoculated coffee, 72 h of fermentation showed high fruity dominance, and 96 h of fermentation was the only one with herbaceous notes. In addition, yeast inoculation increased the intensity of caramel notes in the first 48 h and increased the fruity flavor after 72 h of fermentation. Therefore, the type of fermentation (with or without inoculation) and the chosen fermentation time will depend on the sensorial profile the producer intends to obtain.
... It was found that cofermentation application with Lactobacillus plantarum HLJ29L2 and yeast (DN-1) firmly improved the protein digestibility of crackers . Another work reported by Cassimiro et al. (2023), they developed superior-quality conilon coffee with co-cultivation of LAB and yeasts using the self-induced anaerobic fermentation methodology. However, there is a lack of extensive report on jackfruit and related byproducts fermentation by LAB or mixed strains. ...
Thus far, little is known about whether jackfruit flake, a byproduct of jackfruit, can be used as a fermentation substrate to obtain value-added products through microbial fermentation. Here, jackfruit flake puree was fermented by three different ways: spontaneous fermentation (JF), inoculated with LAB (JFL), inoculated co-fermentation with LAB and yeast (JFC). In contrast to JF, the total polyphenol and flavonoid content and syndrome-associated enzyme inhibition are significantly increased in JFC at the end of fermentation. Electronic tongue analysis revealed that the JFC was significantly lower in astringency and higher in bitterness. 41 volatile compounds were identified during fermentation by HS-SPME-GC–MS, and JFC was richer in honey, rose, and fruity flavors. A total of 290 compounds were screened for discriminative pre- and post-fermentation differential metabolites by non-target metabolomics analysis. These results provide a potential reference for the conversion of jackfruit waste into functional products using fermentation.
... More than a mere technical stage in production, fermentation is a sensory alchemy that transforms raw coffee beans into a truly exceptional tasting experience. Currently, the primary techniques employed in the coffee fermentation process rely on human sensory methods [12], [13], as evidenced by a study involving six certified Q-Grader coffee tasters [14]. This evaluation takes place after the completion of the fermentation and roasting processes, where coffee beverage samples corresponding to each treatment are assessed following the Fine Robusta Cupping protocol. ...
The coffee fermentation process is a crucial step in the production of high-quality coffee. However, the traditional methods of monitoring the fermentation process are subjective, expensive, and time-consuming. In this study, we developed a novel approach using electronic CO2 and temperature sensors, combined with a 3D-printed encapsulation, to monitor and characterize the coffee fermentation process. Our methodology involved the following steps: Development of a sensor probe for aroma characterization during the coffee fermentation process, implementation of a robust data processing pipeline, including clustering techniques and Principal Component Analysis, to effectively identify and classify aromas, collection of data from the sensor probe throughout the fermentation process, analysis of the collected data to identify patterns and trends that correlate with different stages of the fermentation process. The results of our study demonstrate that our proposed approach is an effective and reliable tool for monitoring and characterizing the coffee fermentation process. Our findings suggest that the use of electronic sensors and data processing techniques has the potential to significantly improve the quality and efficiency of coffee production.
... Among these factors, we highlight the potential of fermentation, where microorganisms use fruit compounds as an energy source, changing the composition profile and, consequently, the sensory attributes (Pereira et al., 2021). Coffee fruits can undergo aerobic and/or anaerobic fermentation, either spontaneously (due to endophytic microorganisms) (Pereira et al., 2019;Silva et al., 2008), or induced (by endophytic or added microorganisms) Cassimiro et al., 2023;Pereira et al., 2022). The induced fermentation of C. canephora is a recent alternative to enhance fruit quality, producing unique beverages with different nuances and offering more diversified coffees Souza et al., 2021). ...
This study describes the sensory profile of beverages of Coffea canephora hybrids (clones BRS 2314 and BRS 2357) in natural (N) and fermented (F) versions. Flash Profile and Temporal Dominance of Sensations were performed; physicochemical characteristics were evaluated. Increase in total titratable acidity and reduction in pH was observed with fermentation. BRS 2314 beverages had higher contents of 5‐caffeoylquinic acid and caffeine. Natural coffees were described as having brown/coffee color, coffee aroma and flavor, roasted aroma and flavor, sweet aroma, and sour taste, and presenting dominance of coffee and tobacco flavors, and bitter and sour tastes. Fermented coffees were described as full‐bodied and having non‐characteristic, fermented and herbal aromas, astringent sensation, bitter taste and bitter aftertaste, and residual flavors, with the dominance of chocolate, fermented and roasted flavors, and bitter taste. BRS 2357 beverages were characterized by bitter taste and bitter aftertaste. BRS 2314N beverage presented attributes considered positive for quality.
Practical Applications
The results are relevant for the coffee production chain and consumers. Intervarietal hybrids of Conilon and Robusta are grown in an area characterized by family farming and with great prospects for sustainable production (in the Rondônia/BR state, Western Amazon) and are developed to express the best characteristics of both botanical varieties, as the high potential of Robusta coffees for fine cup beverages. The hybrid clones were successfully evaluated by experts, but the results do not necessarily correspond to the consumers' insights into coffee brew quality. In addition, fermentation allows to produce beverages with different nuances. The joint use of quick methodologies for static (Flash Profile) and temporal (Temporal Dominance of Sensations) sensory descriptions provided a closer representation of the consumers' perception of those products. This information brings new market perspectives for high‐yield Coffea canephora coffees that are now going through a moment of breaking paradigms regarding quality.
... thus indicating a premium quality (70.00-79.00) [37]. In this study, the total scores of SC, WC, and MC were 77.75, 79.50, and 77.25, respectively. ...
The primary processing method of coffee plays a crucial role in determining its flavor profile. In this study, roasted coffee beans were subjected to three primary processing methods, i.e., natural processing (SC), washed processing (WC), and honey processing (MC), that were analyzed by LC-MS/MS and GC-MS metabolomics. Additionally, sensory evaluation was conducted by the Specialty Coffee Association of America (SCAA) to assess coffee flavor characteristics. The results showed that 2642 non-volatile compounds and 176 volatile compounds were detected across the three primary processing methods. Furthermore, significant differentially changed non-volatile compounds (DCnVCs) and volatile compounds (DCVCs) were detected among SC/WC (137 non-volatile compounds; 32 volatile compounds), MC/SC (103 non-volatile compounds; 25 volatile compounds), and MC/WC (20 non-volatile compounds; 9 volatile compounds). Notable compounds, such as lichenin, 6-gingerdiol 5-acetate, 3-fluoro-2-hydroxyquinoline, and 4-(4-butyl-2,5-dioxo-3-methyl-3-phenyl-1-pyrrolidiny)benzenesulfonamide, were identified as important DCnVCs, while ethyl alpha-D-glucopyranoside, 2,3-butanediol, maltol, and pentane-1,2,5-triol were identified as significant DCVCs in SC/WC. In MC/SC, 3-fluoro-2-hydroxyquinoline, etimicin, lichenin, and imazamox were important DCnVCs, whereas ethyl alpha-D-glucopyranoside, 2-pyrrolidinone, furfuryl alcohol, and pentane-1,2,5-triol were import DCVCs. Lastly, MC/WC samples exhibited notable DCnVCS, such as (S)-2-hydroxy-2-phenylacetonitrile O-[b-D-apiosyl-1->2]-b-D-glucoside], CMP-2-aminoethyphosphonate, talipexole, and neoconvallatoxoloside, along with DCVCS including citric acid, mannonic acid, gamma-lactone, 3-(1-hydroxy-1-methylethyl)benzonitrile, and maltol. Therefore, the primary processing method was a useful influence factor for coffee compositions.
El desarrollo del análisis se centra en identificar un conjunto de prácticas efectivas que contribuyan a mejorar la sostenibilidad en la cadena de suministro de cafés especiales. Metodológicamente, el análisis se fundamenta en un ejercicio de análisis de contenido temático en un corpus evaluado a través de un indicador construido que permite medir el impacto estructural de artículos científicos en la base de datos de Web of Science. Como resultado, se identificaron tres categorías de análisis para las prácticas que incluyen múltiples dimensiones de análisis: Tecnología y procesos de producción sostenible; Impacto ambiental y calidad del café; y, Comportamiento del consumidor y valor agregado. A partir de estos hallazgos, se contribuye a responder cómo se pueden mejorar las prácticas de producción, comercialización y consumo de cafés especiales para lograr una mayor sostenibilidad en la cadena de suministro en el mercado internacional.
Background
Building on the success of traditional fermented foods, the coffee industry has experienced a surge in research on the use of yeast in coffee bean fermentation. As the coffee industry continually seeks innovative approaches, it becomes crucial to understand the nuances of yeast’s impact on coffee quality.
Scope and approach
This review explores the transformative impact of yeast on coffee fermentation and product quality. By investigating traditional (wet and dry processing) and emerging techniques (carbonic maceration and induced fermentation), it aims to understand how yeast selection and fermentation methods affect coffee's flavor, aroma, and quality. Additionally, this review provides critical discussions on underexplored topics, such as optimal storage conditions and health properties of fermented coffee, as well as regulatory, safety, and environmental concerns, offering a complete view of yeast's role in enhancing coffee's market appeal and quality.
Key Findings and Conclusions
Based on criteria such as pectinolytic activity, stress tolerance, and aroma production, Saccharomyces cerevisiae and Pichia fermentans are the most studied yeasts affecting coffee quality. Their impact on the chemical of coffee is evident through the accumulation of aroma-enhancing compounds, such as alcohols, aldehydes, organic acids, esters, ketones, and terpenoids. Recent protocols involving co-inoculation between distinct yeast groups and lactic acid bacteria have emerged, exhibiting metabolic synergism and producing coffees with heightened body perception, improved aroma, and enhanced acidity. However, ongoing research is needed to explore novel fermentation systems, storage methods, and sustainable yeast biomass disposal practices, ensuring a more efficient and sustainable future for the coffee market.
A inoculação de culturas microbianas em fermentação de cafés especiais acelera o processo, compete com micro-organismos indesejados e pode imprimir no grão aromas variados que fomentam sua valorização mercadológica. Nesse trabalho foi comparado a ação de diferentes linhagens iniciadoras autóctones e comerciais na fermentação anaeróbica de um cultivar de café arábica numa fazenda localizada em Garça-SP. Cafés predominantes no estádio cereja foram adicionados em Bombonas de 200 L e nestes inoculadas diferentes leveduras e ou bactérias láticas (BAL), sendo as fermentações feitas em área externa a um Galpão por até 94h. Nas amostras foram feitas análises microbiológicas, físicas, químicas, e sensoriais seguindo metotologia americana. As leveduras ORO e CIMA da linha Lalcafé aceleram a fermentação em 24 h do café estadio cereja cultivar Obatã Vermelho quando comparados aos fermentos Nucoffee Artisans, Pichia kluyveri FA (regional) e BAL (M036L-Sacco). As fermentações agiram antagonicamente à família indesejada Enterobacteriaceae, principalmente aonde teve adição de Pichia kluyveri FA. A maioria dessas fermentações resultou em cafés especiais, além de diferentes características sensoriais, e a maior nota sensorial foi obtida do processo com a cultura Artisans-Syngenta. Pichia kluyveri FA teve melhor resultado sensorial quando associada ao fermento BAL Sacco, e as demais culturas de leveduras comerciais aplicadas resultaram em cafés especiais, apresentando variados nuances sensoriais positivos, ou seja, aumentando as possibilidades para as diferentes preferências de mercados consumidores.
Saccharomyces cerevisiae LBTF 21.3, Pichia manshurica LBTF 21.1 and Leuconostoc lactis LBTF 21.1 were used as single and mixed cultures in coffee fermentations. Fermentations carried out in glass jars with P. manshurica LBTF 21.1/ Leuc. lactis LBTF 21.1 showed higher fermentation rates than S. cerevisiae LBTF 21.3/ P. manshurica LBTF 21.1 or S. cerevisiae LBTF 21.3/ Leuc. lactis LBTF 21.1. The highest cup quality was reached with P. manshurica LBTF 21.1/ Leuc. lactis LBTF 21.1 (83.0 points). Full factorial design (2 ² ) carried out with Pichia manshurica LBTF 21.1 revealed that the higher proportion of water added before the fermentation resulted in higher production of acetic acid. A contrary effect of this variable was observed on the production of lactic acid with Leuconostoc lactis LBTF 21.1. Fermentations conducted in bioreactor evidenced the production of acetaldehyde by P. manshurica LBTF 21.1/ Leuc. lactis LBTF 21.1, P. manshurica LBTF 21.1 and Leuc. lactis LBTF 21.1. Additionally, the highest cup quality was reached in fermentations with P. manshurica LBTF 21.1 (82.5 points) followed by Leuc. lactis LBTF 21.1 (81.5 points) and P. manshurica LBTF 21.1/ Leuc. lactis LBTF 21.1 (81.0 points). Fermentations of coffee with single and mixed cultures are interesting strategies for the improvement of the sensory quality.
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The coffee quality is affected by 40% pre-harvest, 40% post-harvest, and 20% export handling. Besides, future risks for the coffee industry are related with climate change and increased pathogens. Considering the importance of the aroma profile and unique flavor of Arabica coffee, most literature focuses on this variety because of the high market share; however, nowadays, Robusta coffee stands out for its increasing industrial value and resistance to drought. In this review, both species are emphasized, highlighting sensory aspects of possible new products mixed with a higher proportion of Robusta given market trends for bitter beverages. In the present work, a systematic search of peer-reviewed literature evaluates how the coffee cup quality and physicochemical characteristics of Robusta and Arabica are influenced by environmental, agronomic, and further processing factors.
Coffee fermentation is pivotal in post-harvest process to attain quality brew. Exploration of improved coffee profile was carried out by solid state fermentation with Yeast, Saccharomyces cerevisiae as starter (Y) on Robusta coffee (CXR variety). The microbial ecology, metabolism, volatomics and organoleptics of Y along with natural fermentation (NF) were evaluated. The proximate composition of mucilage was recorded to have 43.3 Kcal/100g. Fermentation was accelerated by Y populace (13 cfu log/g). The fermentation with Y was 52 h and NF 60h. The green beans displayed 12% moisture, uniform color, size and shape. Changes in alkaloids and chlorogenic acid content were insignificant. The GC-MS accorded additional 10 compounds in Y green coffee (GC), contributing 50.62% of total volatiles compared to NF. The aldehydes (30.1%), alcohols (13.8%), fatty acids (10.7%), and carboxylic acids (10%) are the major volatiles in Y fermented GC followed by Pyrazines and Furans in both the groups. The principal component analysis (PCA) of Y and NF volatilomics denoted 62.10% variance between GC and 99.38% in Roasted coffee (RC). The sensory contours 8 for Y, 6.5 in NF (scale of 0–10). Y can be a determining factor for flavour modulation and quality.
This study characterised a commercial New Zealand gluten free (GF) rice sourdough and its starter culture composition. Acidity of the mother sourdough, dough before proofing and dough after proofing was determined during the production of rice sourdough bread, and colour was measured for the baked bread. Yeast and lactic acid bacteria (LAB) were enumerated in the rice sourdough samples and representative colonies characterised using API kits and sequenced by the Internal Transcribed Spacer and 16 S rRNA region. Sourdough LAB isolates were identified as Lactobacillus (L.) papraplantarum DSM 10667 and L. fermentarum CIP 102980 and the yeast isolates as Saccharomyces (S.) cerevisiae CBS 1171. Dough acidity increased significantly (p < 0.05) during fermentation due to the metabolic activities of the sourdough cultures. After baking, the colour of the rice sourdough bread crust was similar to that of unleavened wheat bread (golden brown). The improved colour of the rice sourdough bread crust may be a result of combined use of sourdough technique and optimal baking conditions. The results of this study may allow bakers to improve the overall quality of GF rice sourdough baked bread by selecting suitable fermentation and baking parameters.
This study aimed to evaluate the beverage quality of Coffea canephora genotypes in different environments of the western Amazon to assist plant selection and new cultivar development. To analyze beverage quality, samples of cherry coffee beans were collected separately for each genotype from clonal competition trials installed in the municipalities of Ouro Preto do Oeste, Alta Floresta do Oeste, Porto Velho, and Ariquemes in Rondônia State and Rio Branco in Acre State (Brazil). The beverage quality was assessed using the Robusta Cupping Protocol, which attribute to each genotype a score in a range from 0 to 100, highlighting nuances. Analysis of variance and principal components using reference points were used to quantify genotype x environment interaction (G x E). The analysis of variance indicated that genotypic and G x E interaction effects were significant (p < 0.01). By using a centroid dispersion method, we could identify four clones of low, eight of specific (to favorable or unfavorable environments), and seven of broad adaptability to the environments. The clones BRS 2314, 11, and 17 had average quality scores above 80 in all environments, with potential for specialty coffee production. The clones BRS 1216, BRS 3220, and BRS 3193 presented unstable behavior, with beans of higher quality in some of the evaluated environments. Such inconsistency in clone behavior is caused by unpredictable changes in plant performance in different environments. Our results indicate that both genotypic (clones) and G x E interaction effects are important for the expression of coffee beverage quality. However, the clones BRS 3213, BRS 3210, and BRS 2299 had less prominent nuances, with lower potential for specialty coffee production.
Hansinaspora uvarum and Pichia kudriavzevii were used as starter cultures to conduct inoculated wet fermentations of coffee beans, and their growth, metabolic activities and impact on the flavor, aroma and overall sensory quality of coffee were compared with spontaneous fermentation (control). H. uvarum and P. kudriavzevii dominated the fermentations, growing to maximum populations of about 10.0 log CFU/ml compared with 8.0 log CFU/ml in the spontaneous fermentation. The dominance of the inoculated yeasts led to faster and more complete utilization of sugars in the mucilage, with resultant production of 2–3 fold higher concentrations of metabolites such as glycerol, alcohols, aldehydes, esters, and organic acids in the fermented green beans. Cup tests showed coffee produced from the inoculated fermentations, especially with P. kudriavzevii , received higher scores for flavor, aroma and acidity than the control. The findings of this study confirmed the crucial role of yeasts in the wet fermentation of coffee beans and their contribution to high quality coffee, and demonstrated the potential H. uvarum and P. kudriavzevii as starter cultures in the process.
BACKGROUND
The terrain slope and field altitude where the plant is cultivated influence the composition of coffee cherries. The aim of this study was to analyze the effects of different levels of altitude and terrain slope on the Coffea canephora cherries, as well as on the quality of the final beverage. C. canephora harvested in fields with 300 and 600 m altitude and with southeast‑ and northwest‐facing slopes was evaluated.
RESULTS
Lower pH values were observed for cherries cultivated at higher altitudes. The highest percentage of soluble solids (525.00 g kg⁻¹) was found on northwest‐facing slopes at 300 m. The highest values of phenolic compounds were observed at 600 m. Significant differences were found in the moisture of coffee cherries grown in different terrain slope and in the fiber content at different altitudes. The results do not enable us to conclude how the altitude and terrain slope influence the mineral content of cherries. Acidity, proteins, lipids, and carbohydrates were not influenced by altitude or terrain slope. The scores of cup quality were significantly affected by the altitude but not by the terrain slope. Coffees from cherries harvested in fields with 600 m altitude obtained the higher scores.
CONCLUSION
Results show that altitude and terrain slope influence some compounds of coffee fruits, whereas others remain unaffected. The findings are important because, during coffee fruits processing, these compounds are used to produce others that will have an influence on the bean and coffee beverage quality. © 2020 Society of Chemical Industry
Syrah must was co-inoculated with mixed cultures of Saccharomyces + O. oeni/Lb. plantarum and Saccharomyces + non-Saccharomyces + O. oeni/Lb. plantarum to evaluate the effect on phenolics and sensory attributes. Reference wines were produced by S. cerevisiae. Malvidin-3-O-glucoside, flavan-3-ols, flavonols and phenolic acids were quantified using a RP-HPLC technique. Physicochemical characteristics and sensory attributes were measured. Total acidity and alcohol in mixed co-inoculations were different from reference wines. The concentration of l-malic acid was 7-times less in mixed co-inoculations. Mixed co-inoculations had ca. 1.3-times more malvidin-3-O-glucoside and phenolic acids than reference wines. Flavan-3-ols and flavonols were not different between mixed co-inoculations and reference wines. Acidity and astringency were least in mixed co-inoculations. Mouthfeel and bitterness least in S. cerevisiae wines. Tasters preferred mixed co-inoculated wines. Mixed co-inoculation is a strategy to contemplate for Syrah vinification but the modalities of inoculation need further investigation. Success depends on a suitable combination of yeast/bacteria and consideration of strain variation.
Removal of the mucilage layer of coffee fruits by a fermentation process has became an interesting strategy to improve coffee quality, which is able to assist the formation of flavored molecules. In this study, four sets of inoculation protocols were evaluated using ripe and immature coffee fruits, respectively, including (i) pure culture fermentation with Pichia fermentans, (ii) pure culture fermentation with Pediococcus acidilactici, (ii) combined fermentation with P. fermentans and P. acidilactici, and (iv) spontaneous, non-inoculated control. The initial pulp sugar concentration of ripe coffee fruits (0.57 and 1.13 g/L glucose and fructose content, respectively) was significantly higher than immature coffee pulp (0.13 and 0.26 g/L glucose and fructose content, respectively). Combined inoculation with P. fermentans and P. acidilactici of ripe coffee beans increased pulp sugar consumption and production of metabolites (lactic acid, ethanol, and ethyl acetate), evidencing a positive synergic interaction between these two microbial groups. On the other hand, when immature coffee fruits were used, only pure culture inoculation with P. fermentans was able to improve metabolite formation during fermentation, while combined treatment showed no significant effect. Altogether, 30 volatile compounds were identified and semi-quantified with HS-solid phase microextraction (SPME)-gas chromatography coupled to mass spectrophotometry (GC/MS) in fermented coffee beans. In comparison with pure cultures and spontaneous process, combined treatment prominently enhanced the aroma complexity of ripe coffee beans, with a sharp increase in benzeneacetaldehyde, 2-heptanol, and benzylalcohol. Consistent with the monitoring of the fermentation process, only P. fermentans treatment was able to impact the volatile composition of immature coffee beans. The major impacted compounds were 2-hexanol, nonanal, and D-limonene. In summary, this study demonstrated the great potential of the combined use of yeast and lactic acid bacteria to improve fermentation efficiency and to positively influence the chemical composition of coffee beans. Further studies are still required to investigate the mechanisms of synergism between these two microbial groups during the fermentation process and influence the sensory properties of coffee products.
Hyperspectral imaging (HSI) is a novel technology for the food sector that enables rapid non-contact analysis of food materials. HSI was applied for the first time to whole green coffee beans, at a single seed level, for quantitative prediction of sucrose, caffeine and trigonelline content. In addition, the intra-bean distribution of coffee constituents was analysed in Arabica and Robusta coffees on a large sample set from 12 countries, using a total of 260 samples. Individual green coffee beans were scanned by reflectance HSI (980–2500 nm) and then the concentration of sucrose, caffeine and trigonelline analysed with a reference method (HPLC-MS). Quantitative prediction models were subsequently built using Partial Least Squares (PLS) regression. Large variations in sucrose, caffeine and trigonelline were found between different species and origin, but also within beans from the same batch. It was shown that estimation of sucrose content is possible for screening purposes (R² = 0.65; prediction error of ~ 0.7% w/w coffee, with observed range of ~ 6.5%), while the performance of the PLS model was better for caffeine and trigonelline prediction (R² = 0.85 and R² = 0.82, respectively; prediction errors of 0.2 and 0.1%, on a range of 2.3 and 1.1% w/w coffee, respectively). The prediction error is acceptable mainly for laboratory applications, with the potential application to breeding programmes and for screening purposes for the food industry. The spatial distribution of coffee constituents was also successfully visualised for single beans and this enabled mapping of the analytes across the bean structure at single pixel level.
The mode of coffee processing strongly influences the quality of green coffee and thereby establishes the characteristic differences in the flavor of wet and dry processed coffees. These variations are due to differences in the metabolic processes occurring within the vital coffee seeds during the course of processing. Biochemical and molecular biological studies revealed that germination is initiated during postharvest treatment, and stress metabolism is induced in the coffee beans, especially while drying. The detected differences in the time courses and amplitudes of metabolic processes are responsible for the distinct substantial composition characteristic of differently processed green coffees, and the peculiarities of wet and dry process coffees are established. Accordingly, it should be possible to modify the substantial composition of green coffee by deliberately changing the processing conditions, thereby improving its quality and health promoting effects.
Fermentation is one of the oldest forms of food preservation in the world. In South America, most fermented beverages are non-dairy products featuring several other food raw-materials such as cereals, fruits and vegetables. Generally, natural fermentations are carried out by yeast and lactic acid bacteria forming a complex microbiota that acts in cooperation. Yeast has a prominent role in the production of beverages, due to the ability to accumulate high levels of ethanol and to produce highly desirable aroma compounds, but lactic acid bacteria are particularly important in fermentation because they produce desirable acids, flavour compounds and peptides that inhibit the growth of undesirable organisms. Amongst the South America beverages based on cereals and vegetables, could be cited the fermented beverages chicha, caxiri, cauim and champús, and cachaça, a fermented and distilled beverage. Genetic and physiological analyses of S. cerevisiae strains isolated from cachaça have been shown to present interesting traits for beer production, such as flocculation and production of aroma compounds, fundamental to high quality beer. The study of these traditional beverages allows the identification of new microorganism strains displaying enhanced resistance or new flavour and aroma profiles that could lead to applications in several industries and ultimately new products
The dynamic of Saccharomyces cerevisiae, Pichia kluyveri and Hanseniaspora uvarum during spontaneous and inoculated cocoa fermentations and their effect on sensory characteristics of chocolate were investigated. Yeast populations were assessed by qPCR. S. cerevisiae was predominant during spontaneous (average 5.4 log cell/g) and inoculated (average 7.2 log cell/g) fermentations. The H. uvarum seemed to be suppressed by the other two yeasts, as it showed similar population (approximately 4.0 log cell/g) even in the inoculated assay. Carbohydrates were consumed quickly at inoculated fermentation (68% and 42% were consumed in the inoculated and control assays respectively, at 24 h). Ethanol content was higher in the inoculated (8.3 g/kg at 48 h) than in the control (4.6 g/kg at 96 h) fermentation. Consumers did not report a significant preference for either chocolate (p < 0.5). However, differences in the flavor attributes were noted, as consumers reported stronger coffee and sour attributes in the inoculated assay. This is the first time qPCR has been used to assess the dynamic of yeasts during the complex fermentation of cocoa beans. The inoculation accelerated the process. S. cerevisiae and P. kluyveri likely contributed coffee, sour and bitter flavors to the inoculated chocolate.
In this work, the occurrence of HMF (5-hydroxymethylfurfural) in honey marketed in Porto Alegre - RS was investigated using Micellar Electrokinetic Capillary Chromatography. The HMF, which is the product of the fructose condensation, is an indicator of honey quality and conservation. Eleven types of honey commercialized in Porto Alegre were analyzed, and all of them contained HMF in a range from 0.191to 6.206 mg.kg-1. In order to quantify the HMF present in the samples, the technique of standard addition was employed. The recovery was 98% and the detection limit was 0.025 mg.kg-1. The allowed limit of HMF in honey, according to the Brazilian Legislation, is 60 mg.kg-1.
This research was conducted to evaluate trigonelline, chlorogenic acids (5-CQA) and caffeine contents in grains of different cultivars of coffee (Coffea arabica L). The cultivars were colleted at the Experimental Farm of the EPAMIG-Lavras, Minas Gerais state, during 2005/2006. The experimental design was completely randomized with eight cultivars of coffee: Oeiras MG 6851, Acaiá Cerrado MG 1474, Catuaí Vermelho IAC 99, Rubi MG 1192, Topázio MG 1190, Mundo Novo IAC 379-19, Catucaí Amarelo 2 SL and Catuaí Amarelo IAC 62. After the harvest on cloth, the fruits were depulped and washed. After the removal of parchment, the grains were dried until reaching 11%-12% moisture. The samples were submitted to caffeine, trigonelline and 5-CQA analysis by HPLC. The cultivars showed differences in the non-volatile compounds under same crop management environment for all cultivars. Catuaí Amarelo IAC 62 and Rubi MG 1192 showed the highest trigonelline contents; Catuaí Amarelo IAC 62, Catuaí Vermelho IAC 99, Rubi 1192 and Oeiras MG 6851 showed the highest 5-CQA contents; Oeiras MG 6851 and Mundo Novo IAC 379-19 cultivars showed the lowest caffeine content.
During the fermentation of Coffea arabica L., the most frequently found pectolytic bacteria were Erwinia herbicola and Klebsiella pneumoniae. These micro-organisms produce pectatelyase which is unable to depolymerize esterified pectins of mucilage without previous de-esterification. Furthermore, the optimal activities are observed at pH 8.5 whereas fermentation conditions are acidic (5.3–3.5). The major lactic acid bacteria, Leuconostoc mesenteroides, do not produce pectolytic enzymes. Only a Lactobacillus brevis strain, rarely isolated with a low frequency, shows a polygalacturonase activity compatible with fermentation conditions. Mucilage decomposition seems to be correlated to acidification and not to enzymatic pectolysis. Inoculation with pectolytic micro-organisms allows microbiological control of the fermentation but does not speed up the process. It would be preferable to use lactic acid bacteria so that the pH remained as close as possible to natural fermentation, where acidification is important. This practice would standardize the coffee fermentation microflora and therefore control the end product quality.
This paper is a concise review of the research on coffee flavour to serve as a rapid reference on the subject. It covers the process of roasting coffee beans, the volatile and non-volatile components generated by the process and the chemical reactions responsible for their formation. Volatile compounds significant on the determination of coffee aroma are given according to the most recent research. Finally, the paper discusses the chemical indexes used over the years to characterize coffee flavour deterioration and estimation of shelf-life. Copyright © 2004 John Wiley & Sons, Ltd.
Considerable knowledge has been accumulated on the volatile compounds contributing to the aroma and flavor of yogurt. This review outlines the production of the major flavor compounds in yogurt fermentation and the analysis techniques, both instrumental and sensory, for quantifying the volatile compounds in yogurt. The volatile compounds that have been identified in plain yogurt are summarized, with the few key aroma compounds described in detail. Most flavor compounds in yogurt are produced from lipolysis of milkfat and microbiological transformations of lactose and citrate. More than 100 volatiles, including carbonyl compounds, alcohols, acids, esters, hydrocarbons, aromatic compounds, sulfur-containing compounds, and heterocyclic compounds, are found in yogurt at low to trace concentrations. Besides lactic acid, acetaldehyde, diacetyl, acetoin, acetone, and 2-butanone contribute most to the typical aroma and flavor of yogurt. Extended storage of yogurt causes off-flavor development, which is mainly attributed to the production of undesired aldehydes and fatty acids during lipid oxidation. Further work on studying the volatile flavor compounds-matrix interactions, flavor release mechanisms, and the synergistic effect of flavor compounds, and on correlating the sensory properties of yogurt with the compositions of volatile flavor compounds are needed to fully elucidate yogurt aroma and flavor.
Lactic acid bacteria play an essential role in many food fermentation processes. They are anaerobic organisms which obtain their metabolic energy by substrate phosphorylation. In addition three secondary energy transducing processes can contribute to the generation of a proton motive force: proton/substrate symport as in lactic acid excretion, electrogenic precursor/product exchange as in malolactic and citrolactic fermentation and histidine/histamine exchange, and electrogenic uniport as in malate and citrate uptake in Leuconostoc oenos. In several of these processes additional H+ consumption occurs during metabolism leading to the generation of a pH gradient, internally alkaline. Lactic acid bacteria have also developed multidrug resistance systems. In Lactococcus lactis three toxin excretion systems have been characterized: cationic toxins can be excreted by a toxin/proton antiport system and by an ABC-transporter. This cationic ABC-transporter has surprisingly high structural and functional analogy with the human MDR1-(P-glycoprotein). For anions an ATP-driven ABC-like excretion systems exist.
This study evaluated the inoculation of Meyerozyma guilliermondii and Bacillus licheniformis, separately or in co-culture, in wet-processed conilon coffee. Wet fermentation was conducted for 48 hours. Mesophilic bacteria, lactic acid bacteria, yeasts, and filamentous fungi were counted during fermentation. The inoculation of B. licheniformis and M. guilliermondii stimulated the multiplication of lactic acid bacteria. Acetic, citric, lactic, oxalic, malic, succinic, tartaric acids, glucose, and fructose were identified in all treatments at different concentrations. Methyl salicylate, 2-heptanol, 2-nonanol, and heptanone were found during fermentation. Methylpyrazine, 2,6-dimethylpyrazine, 2,5-dimethylpyrazine, and 3-ethyl-2,5-dimethylpyrazine identified after roasting notes of “almond” and “chocolate” to the beverages. All treatments were classified as “premium,” with the B. licheniformis treatment receiving the highest score. Bacillus licheniformis obtained better performance in fermentation, increasing coffee score and producing volatile compounds that provided positive sensory notes to the beverage.
The kombucha market is a fast-growing segment in the functional beverage category. The selection of kombuchas on the market varies between the traditional and flavoured kombuchas. Our research aimed to characterise the chemical, microbial, and sensory profiles of the commercial kombuchas. We analysed 16 kombuchas from 6 producers. The dominant metabolites were acetate, lactate, and ethanol, the last of which might put some kombuchas into the alcoholic beverage section in some countries. The metagenomic analyses demonstrated that LAB dominates in green tea, and AAB in black tea kombuchas. The main bacterial species were Komagataeibacter rhaeticus and Lactobacillus ssp, and yeast species Dekkera anomala and Dekkera bruxellensis. The sweet and sour balance correlated with acid concentrations. The free sorting task showed that commercial kombuchas clustered into three main categories “fruity and artificial flavour”, herbal and tea notes”, and “classical notes”. Our research results showed the necessity of the definition of kombucha.
Wet coffee fermentation is widely used in coffee-producing regions such as Colombia and Hawaii, but it is not widespread in Brazil. This study aimed to evaluate inoculating the lactic acid bacteria Leuconostoc mesenteroides CCMA1105 and Lactiplantibacillus plantarum CCMA 1065 and the yeasts Saccharomyces cerevisiae CCMA0543 and Torulaspora delbrueckii CCMA0684 as starter cultures on wet coffee fermentation using the SIAF method (self-induced anaerobiosis fermentation). The microbial activity resulted in high consumption of the carbohydrates glucose (98.6%), fructose (97.6%), and sucrose (100%), in addition to the production of lactic and acetic acids, impacting the final quality of the beverage. A total of 108 volatile compounds belonging to 17 classes were identified in the green and roasted coffee samples, including 2,3-butanediol produced by lactic acid bacteria, contributing to coffee's aromatic profile. The final scores for the coffees from the different treatments ranged from 79.0 to 83.25. The inoculated fermentations were classified as specialty according to the Specialty Coffee Association. Therefore, whole coffee fruit processed via wet using SIAF method and yeast and lactic acid bacteria starter is an alternative for improving wet fermented coffee quality and obtaining coffee beverages with a different sensory profile.
Microbial communities associated with coffee fermentation have been widely investigated. However, few reports about self-induced anaerobiosis fermentation (SIAF) on microbial diversity and the chemical and sensory profile of coffees grown under different environmental conditions have been studied. This study evaluated the microbial, chemical, and sensorial profile of the natural and pulped coffee fermented with and without induced anaerobiosis. The microbial diversity was determined by plating and next-generation sequencing, the chemical profile through 1H NMR and chemometrics analysis, and sensory analysis was conducted by Temporal Dominance of Sensations (TDS). Three hundred and eighty microorganisms were isolated; 149 mesophilic bacteria, 147 lactic acid bacteria, and 84 yeasts. Hanseniaspora uvarum, Lactiplantibacillus plantarum, Leuconostoc mesenteroides, and Weissella cibaria were identified in Monte Carmelo, Três Pontas, Carmo de Minas, and Lajinha in Minas Gerais, Brazil. New generation sequencing (NGS) analysis identified a high yeast species diversity (74). Some metabolites such as chlorogenic acid, sucrose, lactic acid, and trigonelline were identified in fermented coffees with the joint analysis of NMR and the loadings of PC1. Monte Carmelo coffees processed by the pulped method stood out sensorially showed a higher dominance rate for woody, herbaceous and fruity attributes. The SIAF positively impacts microbial behavior, resulting in coffees with a more intensified fruity attribute.
Selected yeasts for coffee fermentation are correlated with changes in chemical compounds and beverage sensory characteristics. This work aimed to evaluate the chemical and sensory modifications of coffee fermented with one yeast (Saccharomyces cerevisiae CCMA 0543, Candida parapsilosis CCMA 0544, or Torulaspora delbrueckii CCMA 0684) and in co-inoculation (from two to two and the three together) by dry processing. Real-time PCR analyzes, total phenolic content and antioxidant activity (DPPH, ABTS, and FRAP), liquid and gas chromatography, and sensory analysis were performed. Caparaó coffees showed a higher C. parapsilosis (6.14 Log cell.g⁻¹) population followed by S. cerevisiae (5.85 Log cell.g⁻¹) and T. delbrueckii (4.64 Log cell.g⁻¹). The total phenolic content has a strong and positive correlation with the fermentation time and the roasted beans and a moderate and positive correlation with DPPH, FRAP, and ABTS. Coffee inoculated with T. delbrueckii reduced caffeine concentration during the fermentation process. In co-cultivation, the trigonelline concentration showed the most significant decrease (around 4 mg.g-1) when inoculated with S. cerevisiae and T. delbrueckii. Detection of some organic acids and volatile compounds during fermentation may indicate that the starter cultures used different metabolic routes. All co-inoculation treatments presented the best sensory scores (greater than 86 points). In the inoculated fermentation, fruity, citric, molasses, freshness, and wine notes appeared. The co-inoculated treatment with S. cerevisiae CCMA 0543, C. parapsilosis CCMA 0544, and T. delbrueckii CCMA 0684 was the best, considering the diversity of sensory notes descriptors and the final concentration of organic acids.
Coffee fermentation involves the action of microorganisms, whose metabolism has a significant influence on the composition of the beans and, consequently, on the beverage's sensory characteristics. In this study, the microbial diversity during the wet fermentation of Coffea arabica L. in the Sierra Nevada of Santa Marta (SNSM) in Colombia was explored by high-throughput sequencing and the resulting cup quality through the standards of the Specialty Coffee Association. The taxonomic assignment of sequence reads showed a high microbial diversity comprised of 695 bacterial and 156 fungal genera. The microbial community was dominated by the Lactic Acid Bacteria (LAB) Leuconostoc, the yeast Kazachstania, and the Acetic Acid Bacteria (AAB) Acetobacter. Co-occurrence relationships suggested synergistic patterns between populations of LAB-AAB, yeasts-AAB, Leuconostoc-Prevotella, LAB-ABB-Selenomonas, and yeasts-fungi-nonLAB-nonAAB, which may result in the production of metabolites that positively impact the sensory attributes of coffee. The beverages produced were classified as specialty coffees, and their score was positively influenced by the fungal richness and the abundance of unclassified Lactobacillales, Pichia, and Pseudomonas. The findings show the richness and microbial diversity of the SNSM and serve as input for future research such as the analysis of microbial-derived metabolites and the establishment of starter cultures in coffee processing that guarantee the generation of high-quality beverages, the standardization of processes, the reduction of economic losses, and the production of value-added products that allow taking advantage of specialty coffee market.
This work aimed to evaluate Coffea canephora's microbiological, chemical, and sensory characteristics at 300 and 600 m elevation plantations processed by the natural method inoculated with yeasts. The coffee was spread on suspended terraces and sprayed with approximately 10⁷ cfu/mL of Meyerozyma caribbica CCMA 1738 or Pichia kluyveri CCMA 1743, separately. Cherries containing bark and parchment were collected during fermentation for microbial groups counting, qPCR, quantification of organic acids, and sugars (HPLC). Volatile compounds (GC–MS) and sensory analyses, cupping test with expert coffee tasters and triangular test with consumers, were performed on roasted coffee beans. The inoculated yeasts persisted during the entire fermentation process. M. caribbica reduced the filamentous fungal population by 63% and 90% in the 300- and 600-m coffees, respectively. The 300-m coffee fruits showed higher concentrations of organic acids in all fermentation times when compared to the 600-m reaching out to 8 times more. Twenty-four volatile compounds were identified in the roasted coffee beans, with the predominance of pyrazines. The 600-m coffee inoculated with M. caribbica showed an increase of more than one point in the score given by certified tasters. Consumers noticed the M. caribbica inoculation in the 300- and 600-m-elevation coffees. M. caribbica is a promising starter culture for Conilon coffee with the potential to increase the beverage quality.
Fermenting in bioreactors can improve coffee quality, standardize the fermentation process, and generate specialty coffees. This work aimed to evaluate novel stainless steel bioreactors with inoculated and non-inoculated coffees processed via natural and pulped natural. Yeast and bacteria populations were evaluated and grown on Yeast Extract Peptone Glucose; De Man, Rogosa, and Sharpe; and Nutrient agar media. Volatile compounds from roasted beans were analyzed in a Gas Chromatography-Mass Spectrometry equipment, and the sensory perception was evaluated through a cup test. The mesophilic bacteria population was statistically significant in pulped natural coffee compared to yeast and lactic acid bacteria. Furans had the highest concentration among the chemical groups. Beverage inoculated with CCMA 0535 presented the highest SCA score. Prune, peach, and floral attributes were only perceived in Nat CCMA 0535. The sensory perception indicated that the inoculated yeasts modified the flavor attributes, enhanced the quality, and increase their SCA scores.
Glucose and fructose are the main fermentable sugars in cocoa pulp. During fermentation, glucose is consumed within 48-72 h and fructose only after 120 h, mainly associated with the preferential use of glucose by microorganisms. In the first stage of this study, the complete genome sequence of a lactic acid bacterium with high fructose consumption capacity (Lactobacillus plantarum LPBF35) was reported. The notable genomic features of L. plantarum LPBF35 were the presence of alcohol/acetaldehyde dehydrogenase gene and improved PTS system, confirming its classification as a “facultatively” fructophilic bacterium. Subsequently, this bacterium was introduced into cocoa fermentation process in single and mixed cultures with Pediococcus acidilactici LPBF66 or Pichia fermentans YC5.2. Community composition by Illumina-based amplicon sequencing and viable counts indicated suppression of wild microflora in all treatments. At the beginning of the fermentation processes, cocoa pulp consisted of approximately 73.09 mg/g glucose and 73.64 mg/g fructose. The L. plantarum LPBF35 + P. fermentans YC5.2 process showed the lowest levels of residual sugars after 72 h of fermentation (7.89 and 4.23 mg/g, for fructose and glucose, respectively), followed by L. plantarum LPBF35 + Ped. acidilactici LPBF66 (8.85 and 6.42 mg/g, for fructose and glucose, respectively), single L. plantarum LPBF35 treatment (4.15 and 10.15 mg/g, for fructose and glucose, respectively), and spontaneous process (22.25 and 14.60 mg/g, for fructose and glucose, respectively). A positive interaction between L. plantarum LPBF35 and P. fermentans YC5.2 resulted in an improved formation of primary (ethanol, lactic acid, and acetic acid) and secondary (2-methyl-1-butanol, isoamyl acetate, and ethyl acetate) metabolites during fermentation. The primary metabolites accumulated significantly in cocoa beans fermented by P. fermentans YC5.2 + L. plantarum LPBF35, causing important reactions of color development and key flavor molecules formation. The results of this study suggest that fructophilic lactic acid bacteria and yeast is a microbial consortium that could improve sugar metabolism and aroma formation during cocoa beans fermentation.
Effect of lactic acid bacteria and yeasts on the structure and fermentation properties of Tibetan kefir grains, International Dairy Journal, https://doi. ABSTRACT 24 25 To better understand the effects of lactic acid bacteria (LAB) and yeasts on the 26 structure and fermentation properties of Tibetan kefir grains (TKGs), we treated 27 TKGs for 1 month with high doses of mycillin and cycloheximide to inhibit LAB and 28 yeasts, respectively. The results showed that in each group of TKGs, Lactobacillus 29 kefiranofaciens was the only dominant and stable bacterial species, and it exhibited 30 two distinct morphologies in TKGs, short rods in the LAB-inhibited group, and long 31 rods in the yeast-inhibited and control groups, which might directly result in the 32 inability of the grains in the LAB-inhibited group to grow further. Compared with 33 bacteria, the relative abundance of yeasts in TKGs was very low. However, even 34 though yeast had no effect on the structure and growth characteristics of TKGs, they 35 had a great influence on the fermentation characteristics of Tibetan kefir, such as acid 36 production and aroma. 37 _____________________________________________________________________ 38 J o u r n a l P r e-p r o o f 1.
Fermentation is one of the post-harvest steps that influence coffee quality. This work evaluated the effect of Saccharomyces cerevisiae (CCMA 0543) and Torulaspora delbrueckii (CCMA 0684) inoculation on the quality of natural and pulped natural processed coffee in different producing regions. Yeast populations were assessed by the real-time polymerase chain reaction. Volatile and nonvolatile compounds were evaluated by gas chromatography-mass spectrometry and high-performance liquid chromatography, respectively. S. cerevisiae was predominant during spontaneous (average of 4 log cells/g) and inoculated (average of 7 log cells/g) fermentations in both processes. T. delbrueckii showed a similar population (3.79 log cells/g) in all assays. Glucose and fructose were the most detected sugars in coffee beans. Succinic acid was found at the end of the fermentative process. The lactic acid concentration was inversely proportional to ethanol concentration. Pyrrole and furan, which are volatile groups, allowed to differentiate the coffee processing methods. Yeast inoculation modified the sensorial profile and increased the coffee beverage scores by up to 5 points. S. cerevisiae inoculation was most suitable for pulped natural coffee, and T. delbrueckii inoculation showed the best performance in natural coffee.
The microbial ecology in the fermentation of Australian coffee beans was investigated in this study. Pulped coffee beans were kept underwater for 36 h before air dried. Samples were collected periodically, and the microbial communities were analyzed by culture-dependent and independent methods. Changes in sugars, organic acids and microbial metabolites in the mucilage and endosperm of the coffee beans during fermentation were monitored by HPLC. Culture-dependent methods identified 6 yeast and 17 bacterial species, while the culture-independent methods, multiple-step total direct DNA extraction and high throughput sequencing, identified 212 fungal and 40 bacterial species. Most of the microbial species in the community have been reported for wet fermentation of coffee beans in other parts of the world, but the yeast Pichia kudriavzevii was isolated for the first time in wet coffee bean fermentation. The bacterial community was dominated by aerobic mesophilic bacteria (AMB) with Citrobacter being the predominant genus. Hanseniaspora uvarum and Pichia kudriavzevii were the predominant yeasts while Leuconostoc mesenteroides and Lactococcus lactis were the predominant LAB. The yeasts and bacteria grew significantly during fermentation, utilizing sugars in the mucilage and produced mannitol, glycerol, and lactic acid, leading to a significant decrease in pH. The results of this study provided a preliminary understanding of the microbial ecology of wet coffee fermentation under Australian conditions. Further studies are needed to explore the impact of microbial growth and metabolism on coffee quality, especially flavour.
The objective of this work was to evaluate the influence of different altitudes on the epiphytic microbiota of coffee beans and on sensorial and chemical quality of coffees grown at 800, 1000, 1200, and 1400 m in Serra do Caparaó, Espírito Santo, Brazil. For microbiological analysis, the population counts of mesophilic bacteria, lactic acid bacteria (LAB), and yeasts were performed from the surface plating. The isolates were grouped and identified from the Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) and sequencing of the ribosomal region was used. The chemical composition of the green grains was evaluated by Raman spectroscopy, and the sensory analysis of the roasted grains was performed using temporal dominance of sensations (TDS). During fermentation, there was a decrease in the LAB in pulped coffee from 800 and 1000 m altitude, while an increase was observed at 1200 and 1400 m. In natural coffee, there was an increase of LAB population at all altitudes. The highest diversity of mesophilic bacteria and yeast were identified in natural 1400 m and 1000 m, respectively. However pulped coffee treatments it was at 1200 m and 800 m. The chlorogenic acid and fatty acids in the green bean changed with altitude variation and processing. The floral attribute was detected only at altitude 1400 m. Caramel, chocolate and almond attributes were most frequently detected in coffees at different altitudes and processing. Therefore, pulped coffee processing was most suitable at low altitude while at high altitudes, both processes can be conducted to obtain a beverage with unusual sensory profile.
Fermented foods and beverages are mainly consumed by the indigenous people of Africa and other developing countries. Traditional fermentation is an age-long means of preserving perishable foods especially when other methods of preservation are not available and/or not consistent. The main beneficial microorganisms that are responsible for the fermentation of African indigenous fermented foods and beverages are lactic acid bacteria and yeasts which may be present as microflora on the substrates or added as starter cultures. The understanding of the synergistic interaction between these microorganisms in the fermented food matrices result in improved nutrient availability, food quality, palatability, organoleptic properties, increased shelf life, safety, digestibility and also play beneficial roles in modulating host immune system thereby minimizing the risk of certain diseases.
While lactic acid-producing fermentation has long been used to improve the storability, palatability, and nutritive value of perishable foods, only recently have we begun to understand just why it works. Since the publication of the third edition of Lactic Acid Bacteria: Microbiological and Functional Aspects, substantial progress has been made in a number of areas of research. Completely updated, the Fourth Edition covers all the basic and applied aspects of lactic acid bacteria and bifidobacteria, from the gastrointestinal tract to the supermarket shelf. Topics discussed in the new edition include: • Revised taxonomy due to improved insights in genetics and new molecular biological techniques • New discoveries related to the mechanisms of lactic acid bacterial metabolism and function • An improved mechanistic understanding of probiotic functioning • Applications in food and feed preparation • Health properties of lactic acid bacteria • The regulatory framework related to safety and efficacy Maintaining the accessible style that made previous editions so popular, this book is ideal as an introduction to the field and as a handbook for microbiologists, food scientists, nutritionists, clinicians, and regulatory experts.
This work evaluated the bacterial diversity during coffee wet fermentation of the three coffee varieties—Mundo Novo (MN), Ouro Amarelo (OA), and Catuaí Vermelho (CV). Isolates were identified by polyphasic techniques: biochemical tests, matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and DNA sequencing. Chemical compositions were determined by high (HPLC) and gas chromatography-mass spectrometry (GC-MS) and the roasted beans were sensorial evaluated using the cupping test. Thirty-six mesophilic bacteria and six lactic acid bacteria were identified. Lactobacillus plantarum and Leuconostoc mesenteroides were often found in all varieties. Citric acid was the acid detected in higher concentrations. The volatile profile of the green coffee beans changed during the fermentation in the tank, but more significantly, during the roasting process. These volatiles belonged to the classes of acids, alcohols, aldehydes, and hydrocarbons. Temporal dominance of sensations analysis showed sensorial sensations of acidity (OA and CV), bitterness, chocolate, nuts (MN), and sweetness (CV). The characteristics of each coffee variety were distinct, mainly in relation to total bacteria population, volatile compounds, and sensorial profile. In conclusion polyphasic methodology was efficiently done for bacteria identification; the dominant bacteria might be used for starter cultures and the chemical and sensory analyses helped to understand the changes in coffee fermentation. Our findings are relevant to future select starter bacteria for coffee processing to improve quality and standardization of quality.
This study evaluates the behavior of Saccharomyces (S.) cerevisiae (CCMA 0543), Candida (C.) parapsilosis (CCMA 0544), and Torulaspora (T.) delbrueckii (CCMA 0684) as starter cultures for semi-dry processed coffee using two inoculation methods: (1) direct inoculation and (2) bucket inoculation. The microbial population was evaluated by plating and real-time polymerase chain reaction (qPCR). The microbial metabolic changes of both bucket and direct inoculation methods during fermentation were evaluated using high performance liquid chromatography (HPLC), and gas chromatography–mass spectrometry (GC–MS). A sensorial test was also carried out. Citric and succinic acids were detected throughout the fermentation period. Chlorogenic acid concentration levels were higher for the bucket method after roasting. Roasted coffee beans also had a higher caffeine concentration, with the exception of the T. delbrueckii (CCMA0684) assay. Acids, pyrazines and pyridines were the main volatile compounds in both green and roasted coffee beans. Coffee cupping results proved that both inoculation methods scored well in terms of coffee quality. The bucket method favored the permanence of the microorganisms during coffee processing, especially the treatment inoculated with S. cerevisiae.
Bacteriocins, defined as ribosomally synthesized antimicrobial peptides, have traditionally been used as food preservatives, either added or produced by starter cultures during fermentation. In-depth studies of a select few bacteriocins opened exiting new research fields and broadened the application of these antimicrobial peptides. The possibility of developing bacteriocins into next generation antibiotics, accompanied with the rapid development in genetics and nanotechnology, paves the way to even more fascinating applications such as novel carrier molecules (delivery systems) and the treatment of cancer. Also, some bacteriocins are found to regulate quorum sensing which suggests novel applications for this group of substances. While there is some interesting translational research on bacteriocins from Gram-negative bacteria, the majority of application-oriented studies are focused on bacteriocins from Gram-positive microorganisms, mostly lactic acid bacteria. The applications of bacteriocins are expanding from food to human health.
Pulped Mundo Novo and Ouro Amarelo coffee beans were inoculated with Saccharomyces cerevisiae (CCMA 0200 and CCMA 0543) during semi-dry coffee fermentation and compared with a non-inoculated control. Samples were collected throughout the fermentation process (12 days) to evaluate the persistence of the inoculum by Real-Time quantitative PCR (qPCR). Also, the chemical composition of the beans was determined by HPLC and GC–MS and the roasted beans were sensorial evaluated using the cupping test. S. cerevisiae CCMA 0543 had an average population of 5.6 log cell/g (Ouro Amarelo cultivar) and 5.5 log cell/g (Mundo Novo cultivar). Citric, malic, succinic and acetic acid were found in all samples, along with sucrose, fructose, and glucose. There were 104 volatile compounds detected: 49 and 55 in green and roasted coffee, respectively. All coffee samples scored over 80 points in the cupping test, indicating they were specialty-grade. Inoculation with the CCMA 0543 strain performed better than the CCMA 0200 strain. This is the first time that qPCR has been used to assess the persistence of the inoculated strains populations during coffee processing. Strain CCMA 0543 was the most suitable as an inoculant due to its enhanced persistence during the process and number of volatile compounds produced.
This study describes, for the first time, the potential use of selected lactic acid bacteria (LAB) to conduct improved coffee bean fermentation during on-farm wet processing. Among different strains tested, Lactobacillus plantarum LPBR01 showed a suitable production of organic acids and flavor-active esters in a coffee pulp simulation medium and was used as starter culture under field conditions. The results indicated that L. plantarum LPBR01 was able to establish an accelerated coffee-pulp acidification process and potentially reduced the fermentation time from 24 to 12 h. The inoculation of LPBR01 strain also increased significantly the formation of volatile aroma compounds during fermentation process (such as ethyl acetate, ethyl isobutyrate and acetaldehyde) and enabled the production of beverage with distinct sensory notes and a remarkable increase in quality compared with the conventional process. Our results suggest that the use of LAB in coffee processing is an ideal alternative way to conduct faster and improved coffee bean fermentation.
The evaluation of the microbiota present during coffee wet fermentation was done in two distinct regions of Minas Gerais, Brazil: one farm in the South of Minas Gerais (Lavras=L) and another farm in the savannah region (Monte Carmelo=MC). The yeast population ranged from 2.48 to 4.92logCFU/g and from 2 to 4.81logCFU/g, the mesophilic bacteria population ranged from 3.83 to 8.47logCFU/g and from 5.37 to 7.36logCFU/g, and the LAB population ranged from 2.57 to 5.66logCFU/g and from 3.40 to 4.49logCFU/g in the L and MC farms, respectively. Meyerozyma caribbica and Hanseniaspora uvarum were the dominant yeasts in coffee wet fermentation at L farm, and Torulaspora delbrueckii was the dominant yeast at MC farm. The species Staphylococcus warneri and Erwinia persicina were the predominant bacteria at L farm, and Enterobacter asburiae and Leuconostoc mesenteroides were the dominant species at MC farm. Lactic acid was the principal acid detected, reaching 2.33g/kg at L farm and 1.40g/kg at MC farm by the end of the process. The volatiles composition was similar for roasted coffee from the two different regions and furans, acids, and alcohol were the main groups detected. Temporal Dominance Sensation (TDS) analyses showed that the coffee beverage from L farm was dominated by citrus and herbaceous sensory characteristics, while the coffee from MC farm was dominated by citrus, herbaceous, and nuts sensory characteristics. Evaluating the microbiota in these two regions was important in improving the knowledge of the microbial species present during coffee wet fermentation in Brazil.
Copyright © 2015 Elsevier B.V. All rights reserved.
Coffee is an important commercial product to Brazil with its consumption distributed globally. The aim of this work was to evaluate the potential of yeast strains as starter cultures for dry fermentation of washed and non-washed coffee beans. Four yeast strains (Saccharomyces cerevisiae UFLAYCN727, S. cerevisiae UFLAYCN724, Candida parapsilosis LELA YCN448 and Pichia guilliermondii UFLA YCN731) were inoculated separately in washed and non washed coffee cherries and in the control was not added any of the starter cultures. The fruits inoculated were spread on trays and placed on a terrace until the coffee beans reached 11% of moisture. Samples were collected for evaluation of the persistence of the inoculum by PCR-DGGE, and for chemical composition by HPLC and GC-FID. Sensory analysis was performed using the Temporal Dominance of Sensations (TDS) methodology. In all tests the yeasts persisted until the end of fermentation. There was no propionic and butyric add production in concentrations that could compromise the final quality of the beverage. Forty-eight volatile compounds were identified, some were similar for green and roasted coffee. The most abundant class of compounds was alcohols (11-27%) followed by furan in roasted grains (similar to 27%), and aldehydes (similar to 13%) in green grains. The coffee inoculated with yeast showed sensations of flavors higher than the control coffee indicating increased sensory quality. The treatment with C parapsilosis UFLA YCN448 showed dominance rate higher (near 1) for the sensation of caramel. In non-washed coffee those sensations were not pleasant in relation to the washed coffee, except when P. guilliermondii UFLA YCN731 was inoculated, suggesting that washing the fruit before the fermentation process positively influenced the final product quality. A coffee with special aroma of caramel, herbs and fruits could be produced using the starter cultures C parapsilosis UFLA YCN448 and S. cerevisiae UFLA YCN727 in coffee processed by the dry method.
Volatile compounds were isolated from Cheddar cheese headspace by purge and trap extraction, enriched by cryofocusing, and analyzed by multidimensional GC equipped with odor port and by GC/MS. In total, 5 aldehydes, 6 ketones, 8 alcohols, 3 esters, 11 hydrocarbons, 3 halides, and 3 sulfur compounds were positively identified. Ethanol, 2,3-butanedione, and 3-hydroxy-2-butanone were the major components isolated in cheese headspace. The paper describes the aroma characteristics of some of these volatiles and their impact on the overall Cheddar flavor. Esters, aldehydes, methyl ketones, and sulfur compounds had direct impact on Cheddar aroma by virtue of their characteristic aroma. On the other hand, alcohols and hydrocarbons formed the major portion of the GC profile but contributed little to the aroma.
The levels of nine chlorogenic acids, caffeine, trigonelline and sucrose were determined by HPLC-UV and HPLC-RI systems in wet and semi-dry post-harvested coffee seeds from 17 Brazilian Arabica cultivars and progenies. Coffees processed by wet method showed higher contents of chlorogenic acids (p = 0.02) and trigonelline (p < 0.01), and lower content of sucrose (p = 0.02) compared to those produced by a semi-dry method. Regarding caffeine, no difference was observed between both methods. The implications of the differences observed in the chemical composition of coffee seeds treated by wet and semi-dry methods on cup quality deserve investigation.
Wine is a highly complex mixture of compounds which largely define its appearance, aroma, flavour and mouth-feel properties. The compounds responsible for those attributes have been derived in turn from three major sources, viz. grapes, microbes and, when used, wood (most commonly, oak). The grape-derived compounds provide varietal distinction in addition to giving wine its basic structure. Thus, the floral monoterpenes largely define Muscat-related wines and the fruity volatile thiols define Sauvignon-related wines; the grape acids and tannins, together with alcohol, contribute the palate and mouth-feel properties. Yeast fermentation of sugars not only produces ethanol and carbon dioxide but a range of minor but sensorially important volatile metabolites which gives wine its vinous character. These volatile metabolites, which comprise esters, higher alcohols, carbonyls, volatile fatty acids and sulfur compounds, are derived from sugar and amino acid metabolism. The malolactic fermentation, when needed, not only provides deacidification, but can enhance the flavour profile.
Volatile components isolated from Hawaiian green coffee beans (Coffea arabica L.) were identified by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). The mass of total volatile components recovered from 200 g C. arabica beans was 2.7 ± 0.3 mg. The volatile components identified in this extract were: ten alcohols, four aldehydes, one ketone, one lactone, three heterocyclic compounds, two hydrocarbons, and two miscellaneous compounds. The major constituents were 3-methyl butanoic acid (32.8%), phenyl ethyl alcohol (17.3%), hexanol (7.2%), 4-hydroxy-3-methylacetophenone (3.7%), and 3-methyl butanol (3.6%). Heterocyclic compounds, important components in providing coffee with their characteristic flavours, were not found in the extract from green coffee beans, except for 2-methoxy-3-(2-methylpropyl)-pyrazine. Copyright © 2002 John Wiley & Sons, Ltd.
Sensory-guided fractionation of a roasted coffee brew by means of sequential solvent extraction, ultrafiltration, and RP-HPLC
demonstrated a group of ethyl acetate soluble compounds formed from O-hydroxycinnamoyl quinic acid derivatives upon coffee roasting as the key compounds contributing to the bitter taste of roasted
coffee beverages. LC-MS/MS studies, 1D- and 2D-NMR spectroscopy, syntheses, and model roast experiments with 5-O-caffeoyl- and 5-O-feruloylquinic acid led to the unequivocal identification of 3-O-caffeoyl-γ-quinide (2a), 4-O-caffeoyl-γ-quinide (3a), 5-O-caffeoyl-epi-δ-quinide (4a), 4-O-caffeoyl-muco-γ-quinide (5a), 5-O-caffeoyl-muco-γ-quinide (6a), 3-O-feruloyl-γ-quinide (2b), and 4-O-feruloyl-γ-quinide (3b) as intense coffee bitter tastants. Besides these individual bitter compounds, a highly complex and intensely bitter HPLC
fraction was isolated from the ethyl acetate extractables of coffee brew. Application of COSY spectroscopy and alkaline hydrolytic
degradation gave strong evidence that the bitter taste of that fraction is due to a multiplicity of rather complex quinic
acid lactone isomers multiply esterified with p-coumaric acid, caffeic acid, ferulic acid, 3,4-dimethoxycinnamic acid, and quinic acid, respectively. As representatives
of this fraction, 3,4-O-dicaffeoyl-γ-quinide (10), 3,5-O-dicaffeoyl-epi-δ-quinide (11), and 4,5-O-dicaffeoyl-muco-γ-quinide (12) have been isolated, purified, and identified as strongly bitter-tasting compounds in roasted coffee. For the first time,
bitter taste recognition thresholds were determined for the individual compounds showing that, strongly depending on their
chemical structure, the bitter threshold levels ranged between 9.8 and 180μmol/l (water).
The magnitude and diversity of the microbial population associated with dry (natural) processing of coffee (Coffea arabica) has been assessed during a 2-year period on 15 different farms in the Sul de Minas region of Brazil. Peptone water-washed samples were taken of maturing cherries on trees (cherries, raisins and dried cherries) and from ground fermentations. The microbial load varied from 3×104 to 2.2×109 cfu/cherry with a median value of 1.6×107 cfu/cherry. The microbial load increased after heavy rainfall on cherries that were drying on the ground. At all stages, bacteria were usually the most abundant group, followed by filamentous fungi and finally yeasts. Counts of bacteria, yeasts and fungi varied considerably between farms and at different stages of maturation and processing and no consistent pattern could be seen. Yeasts showed an increase during the fermentation process. Median counts were not significantly different for fungi, yeasts and bacteria between the 2 years although Gram-negative bacteria dominated in the wet year and Gram-positive bacteria dominated in the dry year. Of a total of 754 isolates, 626 were identified to at least genus level comprising 44 genera and 64 different species. The 164 isolates of Gram-negative bacteria included 17 genera and 26 species, the most common of which were members of the genera Aeromonas, Pseudomonas, Enterobacter and Serratia. Of 191 isolates of Gram-positive bacteria, 23 were spore-forming and included six Bacillus species, and 118 were non-spore-formers of which over half were Cellulomonas with lesser numbers of Arthrobacter, Microbacterium, Brochothrix, Dermabacter and Lactobacillus. Of the 107 yeast isolates, 90 were identified into 12 genera and 24 different species and almost all were fermentative. The most common genera, in decreasing frequency, were Pichia, Candida, Arxula and Saccharomycopsis. There were many rarely described yeasts including Pichia lynferdii and Arxula adeninivorans. Almost all 292 fungal isolates were identified to genus level and 52 were identified to species level. Cladosporium, Fusarium and Penicillium each comprised about one third of the isolates and were found on all farms. Only 3% of the isolates were Aspergillus. Beauvaria, Monilia, Rhizoctonia and Arthrobotrys species were also occasionally found. The microbial flora is much more varied and complex than found in wet fermentations. The genera and species identified include members known to have all types of pectinase and cellulase activities.
Minas cheese is a food product of significant economic importance to the Brazilian dairy industry. With the intent of providing product identity for legal, economic and manufacturing purposes, several studies have been conducted to define the proximate composition, starter and ripening microflora and manufacturing protocol for Minas cheese. However, studies have yet to characterize the flavor character of Minas cheese, namely the volatile profile. For this purpose, volatiles were investigated using dynamic headspace sampling and GC-MS analysis. Quantitation was based on the recovery of authentic compounds where available. A total of 54 compounds were positively identified and 51 quantified, including fatty acids (11), alcohols (14), aldehydes (5), ketones (6), esters (7), terpenes (8) and lactones (2). The impact of individual volatile compounds on the flavor profile of Minas cheese is discussed. Some of major metabolic pathways for their biosynthesis are reviewed to indicate the possible origin of the compounds identified.