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•Relation between yeast cultures, organic acids and volatile profiles is proposed.•Starter cultures exhibit different behavior according to variety and processing.•The use of yeasts ...is an alternative for sensorial differentiation of coffee.•Coffees with different sensorial profiles increase the final value of the product.
Volatile and non-volatile compounds in coffee directly affect the beverage’s quality. This study aimed to demonstrate how the organic acids and volatile profiles were impacted by coffee fermentation using four starter cultures (Meyerozyma caribbica (CCMA 0198), Saccharomyces cerevisiae (CCMA 0543), Candida parapsilosis (CCMA0544), and Torulaspora delbrueckii (CCMA 0684)) inoculated in two varieties of coffee (Bourbon Amarelo and Canário Amarelo) using natural and pulped natural processing methods and sensory perception. Real-time PCR (qPCR) was used to verify the dynamic behavior of yeast populations. Organic acids were detected using high performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC–MS) was used to detected volatile compounds. Sensory analysis was performed on the roasted coffee. Citric, malic, succinic, lactic, oxalic, isobutyric, and propionic acids and 105 volatile compounds were detected. At the beginning of fermentation, treatments with natural processing presented higher number of volatiles compounds. After fermentation, the main compounds groups were acids, alcohols, and aldehydes. The perception of sensory attribute (fruity, nutty, cocoa) varied with the coffee variety, type of processing, and type of inoculum. The use of yeasts is an alternative for sensorial differentiation of coffee variety Canário Amarelo and Bourbon Amarelo. The stainless-steel containers showed good results for coffee fermentation.
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•Environmental conditions affected the dynamical behavior of yeast inoculation.•Yeast inoculation enhanced coffee beverage quality.•Pyrrole and furan groups were able to differentiate ...the coffee processing types.•S. cerevisiae inoculation was the most suitable for pulped coffee.•T. delbrueckii inoculation showed the best performance in natural coffee.
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.
All coffee production stages occur in a microbiome, which is generally composed of bacteria, yeasts, and filamentous fungi. The use of starter cultures in post-harvest processing stages is an ...interesting alternative, since they promote faster removal of mucilage and incorporation of compounds that improve sensory quality, which can result in diverse sensory attributes for the beverage. This study was therefore developed with the objective of evaluating the effect of the following processing procedures on the chemical and sensory characteristics of the coffee beverage: first, fermentation of coffee fruit of the yellow Catucaí variety of Coffea arabica with indigenous microorganisms, followed by inoculation of the starter culture Torulaspora delbrueckii CCMA 0684 during the drying stage. The fruit was divided into two lots, which were differentiated by a natural fermentation process before drying began. The starter culture was inoculated on the coffee at different times during the drying process: at 0 h, 24 h, 48 h, or 72 h after drying began. The sensory attributes, the volatile compound composition of the roasted beans, the organic acid profile, the bioactive compounds, and the fatty acid profile of the green coffee beans were analyzed. The fatty acid and bioactive compound content showed little variation among treatments. Analysis of volatile compounds and organic acids and evaluation of sensory attributes made it possible to distinguish the two treatments. We conclude that natural fermentation of coffee fruit improve the chemical and sensory quality of the coffee beverage. The effect of natural fermentation may be before inoculation of the starter cultures or even during drying.
•Raman spectroscopy associated with chemometrics identified chemical changes in pulped natural coffee stored.•Raman spectroscopy detecting chemical changes in stored coffee before sensory ...analysis.•Modifications of kahweol are related deterioration during storage coffee.
Raman spectroscopy was used to identify chemical changes associated sensory quality of coffee beans, for natural and pulped natural coffee stored in different packaging. The green beans of natural coffee and pulped natural coffee were stored in three types of packaging materials in a commercial warehouse. Sensory analyses were performed, and Raman spectra were collected after 0, 3, 6, 9, 12, and 18 storage months. Raman spectra were used to construct multivariate control charts. The charts, which were constructed using principal component analysis, can only be used to identify chemical changes in the green beans from pulped natural coffee stored in different packaging materials. Raman spectroscopy is more sensitive than sensory analysis for detecting chemical changes in stored pulped natural coffee. The measured changes ultimately affect the quality of the beverage because samples stored for six months in paper packaging were determined to no longer meet the quality control requirements.
The final quality of pre-processed coffees is influenced by the applied drying technology. Thus, the aim of the study was to develop and validate a heated air flow diffusion system to optimize and ...reduce the drying time of rotary dryers and improve the final quality of coffee. Computational fluid dynamics was used for the simulation of the air fluid dynamics in the combustion chamber of the heat generator. It was observed that the energy losses in the upper and lower walls of the heat generator chamber were higher with an increase in the convective heat transfer coefficient. It was found that the rate of fluid flow presented a fully developed profile, in which the higher speed value was found in the central region of the outlet. The reduction in moisture content during coffee drying was directly proportional to the increase in temperature. The Midilli model shows the best fit to describe the drying curves of the coffee. The effective diffusion coefficient increases with increasing temperature of the drying air. It was observed that the adjustments of the fluid dynamics in the burning of gas and the adaptation of the diffuser system significantly influenced the drying time and final quality of naturally processed and pulped coffees. In conclusion, the adapted technological set, a rotary dryer with gas heating and diffusion of heated air, had a high performance in the final quality of the coffee, and for this reason it is recommended to producers and the industry.
Starter cultures during fermentation of Coffea arabica var. Mundo Novo processed in open stainless-steel vessels by natural and pulped natural methods were studied. The yeasts Meyerozyma caribbica ...(CCMA 0198), Saccharomyces cerevisiae (CCMA 0543), Candida parapsilosis (CCMA 0544), and Torulaspora delbrueckii (CCMA 0684) were inoculated separately in two different coffee processes: natural and pulped natural. The qPCR (real-time quantitative polymerase chain reaction) was used as a culture-independent method to monitor the inoculum's permanence. Changes in microbial metabolites (organic acids and volatile) production were evaluated by high-performance liquid chromatography (HPLC) and gas chromatograph-mass spectrometry (GC–MS), respectively. The sensory analysis was assessed in roasted beans. The fermentation lasted 27 h, and the coffee temperature ranged from 16.5 to 24.0 °C. The starter culture population was dominant throughout fermentation. S. cerevisiae (CCMA 0543) and T. delbrueckii (CCMA 0684) presented a higher population in natural processing. However, in pulped natural processing, M. caribbica (CCMA 0198) and C. parapsilosis (CCMA 0544) were the dominant populations. Citric, malic, and succinic acids were naturally present in coffee. Lactic, isobutyric, and isovaleric acids were detected at the end of the fermentation in different treatments. Lactic acid was detected in samples at the end of fermentation in Control and CCMA 0198 treatment. NAT coffee inoculated with CCMA 0684 presented isobutyric acid and isovaleric acid concentrations. Volatile compounds, such as 2,6-diethylpyrazine was detected in treatments inoculated with yeasts, but not in Controls. 2-acetoxymethylfuran was only detected in samples inoculated with CCMA 0198 from both NAT and PN methods. Samples fermented with S. cerevisiae (CCMA 0543) presented the highest sensorial scores in both processing (84.75 and 84.92). The inoculated coffee beans showed higher scores of sweetness, long aftertaste, and greater complexity. The starter cultures influenced the sensorial profiles through the synthesis of specific volatile constituents. However, considering all parameters analyzed, S. cerevisiae (CCMA 0543) would be the most suitable yeast for the var. Mundo Novo processed by both fermentation methods.
•A new method of inoculation to improve coffee quality has been proposed.•Yeasts exhibit different behavior for natural and pulped natural processing.•Selection of yeast as a starter culture in fermentation coffee var. Mundo Novo.•Starter yeasts produced different aroma compounds in the fermentation process.•The use of yeasts is an alternative to the sensorial differentiation of coffee.
The results of sensory evaluations of coffees are associated with latent factors, such as the particular subjectivity of each individual. Based on the foregoing, assessing the quality of a sensory ...panel for product discrimination basically depends on the statistical methodology to be used in data analysis. Following this argument, this study aimed to evaluate the feasibility of the EM - Expectation Maximization algorithm in discriminating groups of individuals, characterized by the degree of experience and knowledge in sensory analysis of coffees of different varieties, produced in the Serra da Mantiqueira micro-region, with different processing and altitudes. The main advantage of this algorithm is the fast convergence, when the current solution approaches the optimal solution with high precision. The disadvantage is because it is a deterministic optimization technique, which can only achieve a local optimization depending on the initialization, i.e., initial values input in the iterative procedure. It can be concluded that estimates of the correlation matrices obtained by the EM algorithm showed that the final grade has a greater influence of sweetness, in addition to discriminating groups of consumers with different sensory perceptions and in situations where the number of individuals in each group is unknown, the EM algorithm was accurate in estimating the proportion of individuals belonging to each group, assuming that the correlations of sensory responses follow a bivariate normal distribution.
•High barrier packaging can be used as a replacement for vacuum packaging without loss of quality for 18 months of storage.•It is possible to anticipate by up to 3 months the identification of ...chemical changes that would only be noticed through sensory analysis after six months of storage.•Choline and glycerophosphocholine were associated with changes in aging of green coffee packaged in paper bags.
Nuclear magnetic resonance (NMR) was used to identify metabolic changes in green coffee beans stored in 3 different packages. Sensory and NMR analyses were performed at 0, 3, 6, 9, 12 and 18 months of storage. The decrease in the sensory quality of beverages by aging was more pronounced in the paper bags after 6 months of storage. High barrier bags and vacuum packs were able to maintain quality for 18 months of storage, regardless of the coffee processing method. The NMR technique allowed the differentiation of coffee packed in paper bags from the 3rd month of storage. These results indicate that it is possible to anticipate by up to 3 months the identification of changes that would otherwise only be noticed through sensory analysis after six months of storage. Choline and glycerophosphocholine are the main chemical compounds associated with the changes observed in the storage of green coffee in paper bags.
Sensory analysis is one of the most important techniques to assess coffee quality. This study aimed to evaluate the sensory effect of inoculating two varieties of coffee (Ouro Amarelo and Mundo Novo) ...processed by a semi-dry method, with three yeast strains (Saccharomyces cerevisiae CCMA 0200 and CCMA 0543 and Torulaspora delbrueckii CCMA 0684, respectively) obtained from the Culture Collection of Agriculture Microbiology (CCMA). Two sensory analysis techniques were used (cup taste and temporal dominance of sensations analysis). Pulped coffee beans were inoculated with the respective yeast strains and compared to a non-inoculated (control) sample. Ouro Amarelo showed the highest scores for the attributes evaluated compared to variety Mundo Novo. The use of strains CCMA 0543 and CCMA 0684 improved the beverage sensations of both coffee varieties. Variety Ouro Amarelo inoculated with CCMA 0543, highlighted acidity and nuts sensations and Mundo Novo inoculated with CCMA 0543 and CCMA 0684 treatments, respectively, reduced the astringency sensation. The addition of CCMA 0543 starter culture highlighted the acidity of the coffee, improving the sensory results among the yeast strains, for both coffee varieties. The use of two sensory analysis techniques provided better descriptive and comparative analysis of the sensory characteristics of the treatments.
•Sensory analysis of two varieties of coffee inoculated with yeasts.•Strains of Saccharomyces cerevisiae and Torulaspora delbrueckii improve quality of beverage.•TDS and cupping proof provided better descriptive results of sensory characteristics.•S. cerevisiae CCMA 0543 improve acidity and nuts sensations in coffee of Ouro Amarelo variety.•S. cerevisiae CCMA 0543 and T. delbrueckii reduced astringency sensation in Mundo Novo variety.
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