Quality Of Coffee Beverage Research Articles

Genetic diversity of the fungal community that contributes to the sensory quality of coffee beverage after carbonic maceration and fermentation.

Understanding the effects of microorganisms on coffee fermentation is crucial to ensure sensory quality and food security. The analysis of the dynamics of the microbial community during fermentation can contribute to a better understanding of the beneficial and harmful effects of microorganisms and help select starter cultures to improve coffee quality. Furthermore, the anaerobic environment produced by carbonic maceration of the coffee fruits inhibits aerobic respiratory processes and stimulates fermentative metabolism, modulating the microbial community during coffee fermentation. This study evaluated the effects of carbonic maceration in the fungal community dynamics during the fermentation of Coffea arabica fruits at 18, 28, and 38°C for 24, 48, 72, 96, and 120h. Fungal diversity was accompanied by high-throughput sequencing (NGS) of the Internal Transcribed Spacer (ITS) region. During the coffee fermentation, the fungal community changed over time, with the most significant changes occurring at 18 and 28°C after 72h. However, at 38°C, there were greater variations in fungal composition and fungal diversity was highest after 120h. The yeast Pichia cephalocereana was predominant in the fermentations. These results indicated that temperature and fermentation conditions influence the fungal community during coffee fermentation. Lower temperatures might favor a more stable microbial environment, while higher temperatures lead to more intense changes. Thus, our data from NGS can help in the identification, isolation, and metabolic characterization of fungi for the fermentation of coffee fruits.

Increased fruit load influences vegetative growth, dry mass partitioning, and bean quality attributes in full-sun coffee cultivation

Coffee fruits are highly competitive compared to other functional sink organs. This can affect the vegetative growth of the shoot, dry mass partitioning, and the size and amount of healthy beans. Therefore, this research aimed to evaluate changes in vegetative growth, physical and sensory attributes of the coffee bean, and total crop yield in response to varying fruit load at the tree level established under full-sun cultivation. The experiment was carried out for two consecutive years under field conditions with coffee trees of the cultivar “Cenicafé 1.” Nine different fruit load intensities at the whole-plant level of 20, 30, 40, 50, 60, 70, 80, 90, and 100% were evaluated. The vegetative growth of leaves and branches, leaf area-to-fruit ratio, and dry mass accumulation were evaluated, and growth indices were calculated. Total coffee fruit production, size and distribution of healthy beans, and sensory analysis were determined. As expected, for coffee trees with a 100% fruit load, we found significant decreases in the total number of leaves, leaf area-to-fruit ratio, and branch growth; less dry mass allocated to leaves and branches with a negative correlation between this and the fruit dry mass accumulation; and lower distribution of large and healthy beans. Unexpectedly, annual and accumulated patterns of total production and sensory quality of coffee beverage were not affected by the high fruit load. The findings suggest that increased fruit load in coffee trees of the “Cenicafé 1” variety led to changes in vegetative growth, dry mass partitioning, and physical quality of the beans. However, there was no impact on production patterns and sensory attributes.

Enhancing Sensory Quality of Coffee: The Impact of Fermentation Techniques on Coffea arabica cv. Catiguá MG2.

Fermentation, a critical post-harvest process, can be strategically manipulated to augment coffee quality. This enhancement is achieved through the activity of microorganisms, which generate metabolites instrumental in the formation of distinct sensory profiles. This study investigated the impact of different fermentation methods on the quality of coffee beverages, specifically utilizing the Catiguá MG2 variety. The experimental setup involved fermenting the coffee in 200 L bioreactors, employing both natural and pulped coffee beans. The fermentation process utilized was self-induced anaerobic fermentation (SIAF), conducted in either a solid-state or submerged medium over a 96 h period. Analytical sampling was conducted initially and at 24 h intervals thereafter to quantify the concentration of sugars, alcohols, and organic acids. Sensory evaluation was performed using the established protocols of the Specialty Coffee Association (SCA). The outcomes of this investigation reveal that fermentation substantially enhances the quality of coffee, with each treatment protocol yielding divergent profiles of acids and alcohols, thereby influencing the sensory characteristics of the resulting beverage. Notably, superior quality beverages were produced from naturally processed coffee subjected to solid-state fermentation for durations exceeding 24 h. These findings underscore the significant influence of fermentation techniques and duration on the sensory attributes and overall quality of coffee.

Purchasing Decisions and Consumer Preferences of Millennials and Zoomers at Coffee Shops

The transformational era has given rise to a new generation that is presumed to have different preferences than the previous generation. The proliferation of coffee shops has expanded consumer alternatives for purchasing decisions. This research aims to identify and segment Millennial and Zoomer consumers based on demographic, behavioral, and psychographic characteristics in the purchase of coffee beverages at coffee shops. The research employed a non-probability sampling method, specifically judgmental sampling, with a sample size of 180 coffee shop consumers in Madiun City. The data were analyzed using descriptive statistics, independent sample t-tests, and K-means clustering. The research findings indicate that millennials and Zoomer consumers tend to be dominated by females, mostly visiting once a week for leisure and prioritizing taste quality. There are significant differences between Millennial and Zoomer consumers in terms of promotional media attributes, WiFi/power outlet availability, live music entertainment, ordering process, and payment options. Based on consumer segmentation analysis, three segments were identified: coffee enthusiasts, adventurous coffee connoisseurs, and consumers who prioritize coffee beverage quality. The managerial implications for coffee shops involve directing marketing strategies specifically towards the adventurous taste segment and emphasizing quality by prioritizing innovation and differentiation in serving high-quality coffee beverages.

Inoculação de Saccharomyces cerevisiae com caldo de cana-de-açúcar como cultura iniciadora na fermentação do café (Coffea arabica)

ABSTRACT This study aims to evaluate the effect of sugarcane juice and the addition of commercial yeast Saccharomyces cerevisiae var. bayanus (≥ 1 × 1010 cfu/g) during the fermentation of coffee to the beverage’s sensory characteristics and the coffee bean’s chemical composition. A completely randomized experimental design with two replicates is carried out for four treatments, distributed as follows: i) water addition (0.78 kg), ii) sugar cane juice addition (0.78 kg), iii) sugar cane juice addition (0.78 kg) combined with yeast Oenoferm® Freddo (0.12 g) and iv) sugar cane juice addition (0.78 kg) combined with yeast Oenoferm® Color (0.12 g). After fermentation and drying, the samples were subjected to medium roasting and analyzed using infrared spectroscopy and sensory analysis according to the methodology of the Specialty Coffee Association. The implementation of organic additives directly affected the attributes and sensory notes, allowing coffee to be classified as a specialty coffee with a score above 80 points. Adding sugar cane juice or a combination of sugar cane juice and Saccharomyces cerevisiae showed promising results in improving coffee beverage quality. Additionally, chemometric analysis of the infrared spectrum showed that the chemical characteristics of roasted coffee were affected, which correlated with the sensory results. The addition of cane juice only (T2) and the Oenoferm® Freddo yeast strain (T3) presented the best sensory quality.

Microbial Diversity of Anaerobic-Fermented Coffee and Potential for Inhibiting Ochratoxin-Produced Aspergillus niger.

Coffee flavor considerably depends on the fermentation process, with contributing factors including fermentation temperature, oxygen concentration, and microbial diversity. Efficient controlling of the fermentation can improve the quality of coffee beverages. Therefore, several studies on coffee fermentation processes have been conducted in various regions. The objective of this study was to assess the microbial diversity of coffee beans undergoing anaerobic fermentation at various temperatures (4 °C or 37 °C) and fermentation durations (12 h or 36 h) using full-length 16S rRNA sequencing. This analysis aimed to evaluate the inhibitory effects of the fermented metabolites against ochratoxin-producing Aspergillus niger. From our results, Acetobacter was identified as the dominant microbial community at higher fermentation temperatures, whereas Leuconostoc and Gluconobacter were the dominant genera at lower temperatures. However, at lower temperatures, changes in microbial communities were relatively slow. This study expands our knowledge of the microbial diversity involved in the anaerobic fermentation of coffee beans in Taiwan. The findings of this study can be used in future research to cultivate microorganisms linked to the quality and improve the quality of coffee beverages through fermentation.

POTENCY OF YEAST AS A BIOCONTROL AGENT OF OCHRATOXIN A-PRODUCING FUNGI AND ITS EFFECT ON ARABICA COFFEE TASTE

Biocontrol agents can be used to control mycotoxigenic fungi, which include different species of yeast. The objectives of this research were to select yeast isolates that can inhibit the growth of ochratoxin A (OTA)-producing fungi (Aspergillus ochraceus BIO 37310) and to increase the taste of Arabica coffee processed using wet and semi-wet methods. Twenty-two yeast isolates (KA, KA2, KB, KB2, KC, KD, Endomyces decipiens BIO 131215, E. fibuliger BIO 132216, BIO 132217, BIO 13218, BIO 132219, BIO 132220, Candida krusei (= Issatchenkia orientalis) BIO 211285, BIO 211286, BIO 211287, BIO 211288, BIO 211289, BIO 211290, BIO 211291, Saccharomyces cerevisiae BIO 341363, BIO 341364, and BIO 341365) were screened for their antagonistic property against A. ochraceus BIO 37310 in vitro using well (dip) test method. The results showed that C. krusei (BIO 211287, BIO 211288, and BIO 211289) inhibited A. ochraceus BIO 37310. In vivo the highest yeast population was found in coffee beans processed using a semi-wet method inoculated with C. krusei BIO 211288 (46,222 ± 9,576 cfu/g), which was not significantly different from that of the coffee beans inoculated with C. krusei BIO 211287 (36,333 ± 14,000 cfu/g). The three yeast isolates were also able to grow either in coffee beans processed using wet or semi-wet methods inoculated with A. ochraceus BIO 37310 and each yeast isolate. Interaction between the three yeast isolates and A. ochraceus BIO 37310 resulted in E-type interaction, i.e. the fungus was not able to grow anymore, while the yeasts grew further. The total cupping scores of coffee beans inoculated with the three yeast isolates were higher than those of coffee beans uninoculated and inoculated with commercial lactic acid bacteria. The three yeast isolates could be used as biocontrol agents of A. ochraceus BIO 37310 and increase the sensorial quality of coffee beverages.

Genetic-environment interactions and climatic variables effect on bean physical characteristics and chemical composition of Coffea arabica.

The effects of the environment and genotype in the coffee bean chemical composition were studied using 9 trials covering an altitudinal gradient (600-1100 m.a.s.l) with 3 genotypes of Coffea arabica in the Northwest mountainous region of Vietnam. The impacts of the climatic conditions on bean physical characteristics and chemical composition were assessed. We showed that the environment had a significant effect on the bean density and on all bean chemical compounds. The environment effect was stronger than the genotype and genotype-environment interaction effects for cafestol, kahweol, arachidic (C20:0), behenic acid (C22:0), 2,3-butanediol, 2-methyl-2-buten-1-ol, benzaldehyde, benzene ethanol, butyrolactone, decane, dodecane, ethanol, pentanoic acid, and phenylacetaldehyde bean content. A 2°C increase in temperature had more influence on bean chemical compounds than a 100 mm increase in soil water content. Temperature was positively correlated with lipids and volatile compounds. With an innovative method using iterative moving averages, we showed that correlation of temperature, VPD and rainfall with lipids and volatiles was higher between the 10th and 20th weeks after flowering highlighting this period as crucial for the synthesis of these chemicals. Genotype specific responses were evidenced and could be considered in future breeding programs to maintain coffee beverage quality in the midst of climate change. This first study of the effect of the genotype-environment interactions on chemical compounds enhances our understanding of the sensitivity of coffee quality to genotype environment interactions during bean development. This work addresses the growing concern of the effect of climate change on speciality crops and more specifically coffee. This article is protected by copyright. All rights reserved.

Heat and Mass Transfer Kinetics on the Chemical and Sensory Quality of Arabica Coffee Beans

Roasting has been used by the coffee industry to promote changes in the physical and chemical structure of coffee beans that influence the sensory quality of coffee beverages. However, there are no standardization rules for the temperature and roasting time. Thus, this study evaluated the influence of four roasting profiles obtained by two different roasters on the chemical and sensory quality of the coffee bean. Baked, light, medium, and dark roasting were evaluated using medium infrared spectroscopy and cupping test. Individual and joint effects of temperature and time for each roasting profile were observed on the loss of grain mass. There are specific regions in the infrared spectrum that can be used as markers to discriminate the roasting profiles and the type of roaster used. Despite the difference observed in the ranges of the infrared spectra, the roasters did not present significant differences in the average of the final sensory notes. This result shows the need to use analytical chemical techniques together with sensory analysis in order to better determine differences between coffee samples. Therefore, differences observed in the chemical analyzes and in the sensory attributes of roasted coffee are related to the roasting profile and type of roaster.

Mapping the mountainous climate in the Matas de Minas region, Brazil which influences the top-quality coffee beverages

All the characteristics of the mountainous environment directly influence the coffee crops, and subsequently, on the final coffee note, that reflects the quality of the beverage produced in a region. Despite increasing coffee research, little is known about the influence of the water indices, factors, and the elements of climate on top-quality coffee production potential. Thus, the present study was carried out aiming to analyze the water indices, causes, and aspects of clime, to identify those that most contribute to the potential production of high-quality Arabica coffee beverages in a mountain environment. We considered harvesting the coffee fruits at the cherry stage in 26 municipalities in the Matas de Minas region in the Atlantic Forest Biome in the eastern state of Minas Gerais, and the International Cup of Excellence method was adopted for the sensory evaluation. The principal components analysis and the multiple linear regression (MLR) were used to relate the local environmental variables with the final grade of the coffee beverage. As a result, the Multiple Linear Regression model showed the value of 0.63 for R2. This result means that the joint variability of all the variables considered explained 63% of the changes in coffee beverage quality. And the altitude impact on the grade achieved for the coffee beverage produced in the Matas de Minas region, represented by β, was 0.008068, meaning that for every 100 meters of increase in the altitude, there is an approximate increment of 0.8 points in the final note achieved for the coffee beverage. Among all the environmental characteristics studied, the climatic factor altitude was the main contributor to the coffee top-quality production potential in the Matas de Minas region.

New approach for screening of microorganisms from Arabica coffee processing for their ability to improve Arabica coffee flavor.

The purpose of this research was to isolate microorganisms from coffee fermentation processes and screen them for their potential to improve the flavor of Arabica coffee using a new approach that included pectin degradation ability and growth in mucilage broth. All of the studied microorganisms were isolated from 38 different samples of fresh coffee cherries, coffee mucilage and coffee pulp. A total of 262 microbial isolates were obtained and subjected to screening using pectinase screening agar medium for pectinolytic organisms. The results of the pectinase production test showed that 18 yeast isolates were found to produce pectinase that could degrade the pectin present in solid media. The sugar assimilation profiles and growth of selected strains in mucilage broth were studied. Therefore, 18 isolates from the selected yeasts were subjected to molecular identification by the use of 18S rRNA gene sequencing. The diversity of the yeast isolates was studied, and they were identified as Wickerhamomyces anomalus, Naganishia liquefaciens, Pichia kudriavzevii, Kazachstania naganishii and Kazachstania sp. Moreover, isolates SWU3YWP1-3, SWU3YSK9 and INFCY1-4 were used as a seed culture for Arabica coffee fermentation. The cupping sensory scores of the control (without yeast inoculation) and those inoculated with three isolated yeast strains that were determined by Q-Arabica Graders were 73.75, 84.75, 80.25 and 75.00, respectively. Unique flavors and aromas were detected. This is the first report of screening microorganisms from the Arabica coffee fermentation process by the combination of various properties with success in improving the quality of coffee beverage.

Chemical and sensory characteristics in the selection of bourbon genotypes

The evaluation of coffee quality in Brazil for commercialization is conducted mainly through sensory analysis, also known as the "cup test", in which professional tasters evaluate and score various attributes. The adoption of chemical methods could complement the sensory classification of beverages, if correlations between these chemical and sensory analyses exist, making classification less subjective. This work aimed to identify the relationships between the chemical and sensorial traits of coffee-beverage quality and to evaluate the use of these traits as criteria for the selection of Bourbon cultivars. Twenty coffee genotypes from the first three harvests across five municipalities of the state of Minas Gerais, Brazil were evaluated. The genotypic values, predicted for each genotype, were used to determine the index based on the sum of ranks from Mulamba and Mock. The genetic correlations among the evaluated traits were also estimated. The presented evaluations were not able to efficiently detect genetic and phenotypic relationships between the chemical and sensorial characteristics of drink quality, but as selection criteria for generation advancement in the beverage quality, it is possible to use these characteristics. Bourbon Amarelo LCJ 9-IAC, Bourbon Amarelo-Procafé, Bourbon Amarelo-Boa Vista, Bourbon Vermelho-São João Batista, and Bourbon Amarelo-Samambaia were the genotypes with the most promising cup quality in the studied regions. Through the selection of these five genotypes, the selection gain was 1.65% for sensory score for beverage quality, when the interaction among the studied environments was removed. The heritability was 92% for improving this trait.

Evaluation of genetic divergence of coffee genotypes using the volatile compounds and sensory attributes profile.

The quality of the coffee beverage is related to the chemical, physical, and sensory attributes of the coffee beans that vary with the geographic location of the crop, genetic factors, and post-harvest processing. So, the objective of this study was to evaluate the genetic divergence of 27 genotypes of Coffea canephora using the volatile compounds and sensory attributes profile to select genotypes that produce a coffee beverage with high sensory quality. This genetic diversity was estimated from the Euclidean distance matrix using non-standard data and the Unweighted Pair-Group Method Using Arithmetic Averages (UPGMA). The 2-furyl-methanol, 4-ethenyl-2-methoxyphenol, furfural, 5-methylfurfural, methylpyrazine, and 2,6-dimethylpyrazine were predominating volatile compounds in the genotypes. The sensory attributes had a positive Pearson's correlation with the total score. The volatile compounds had a different relative contribution to the genetic divergence between the genotypes of C. canephora. The 4-ethenyl-2-methoxyphenol, 2-furyl-methanol, and furfural were volatile compounds that most contributed to the formation of the groups in the UPGMA dendrogram. The relative contribution of sensory attributes to dissimilarity among genotypes was 6.42% to 20.20%. Therefore, this study verified the relative contribution of volatile compounds, in specially 4-ethenyl-2-methoxyphenol, 2-furyl-methanol, and furfural, and sensory attributes (flavor, mouthfeel, and bitterness/sweetness) to the genetic divergence between the genotypes of the three clonal varieties. Thus, this work points out compounds that positively contribute to the sensory quality of the Conilon coffee beverage.

From Plantation to Cup: Changes in Bioactive Compounds during Coffee Processing.

Coffee is consumed not just for its flavor, but also for its health advantages. The quality of coffee beverages is affected by a number of elements and a series of processes, including: the environment, cultivation, post-harvest, fermentation, storage, roasting, and brewing to produce a cup of coffee. The chemical components of coffee beans alter throughout this procedure. The purpose of this article is to present information about changes in chemical components and bioactive compounds in coffee during preharvest and postharvest. The selection of the appropriate cherry maturity level is the first step in the coffee manufacturing process. The coffee cherry has specific flavor-precursor components and other chemical components that become raw materials in the fermentation process. During the fermentation process, there are not many changes in the phenolic or other bioactive components of coffee. Metabolites fermented by microbes diffuse into the seeds, which improves their quality. A germination process occurs during wet processing, which increases the quantity of amino acids, while the dry process induces an increase in non-protein amino acid γ-aminobutyric acid (GABA). In the roasting process, there is a change in the aroma precursors from the phenolic compounds, especially chlorogenic acid, amino acids, and sugars found in coffee beans, to produce a distinctive coffee taste.

Cluster analysis of coffee blends for some sensory properties: a comparative approach to the ABIC’s classification criteria

In Brazil, coffee beverage quality is classified according to technical recommendations of the Associação Brasileira da Indústria de Café (ABIC), which determines cutoff points to discriminate from non-recommended to gourmet coffees. Accordingly, this study aimed to propose the use of cluster analysis to evaluate coffee blends composed of coffees with different qualities and of different varieties regarding a few sensory properties, using continuous and binary scales obtained by a cutoff, which defines whether the coffee is recommendable or not according to the ABIC criteria. It is believed, therefore, that this technique can be used to analyze coffee beverage quality as it is easily accessible and implemented by researchers. In conclusion, a qualitative cluster analysis using the minimum cutoff value of the ABIC had more promising results. This is because blends whose composition contained high and moderate proportions of specialty coffees were more homogeneous in the clustering.

Beverage quality of Coffea canephora genotypes in the western Amazon, Brazil

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.

Classification of Lampung robusta Specialty Coffee According to Differences in Cherry Processing Methods Using UV Spectroscopy and Chemometrics

The postharvest processing factors including cherry processing methods highly influence the final quality of coffee beverages, especially in the composition of several coffee metabolites such as glucose, fructose, the amino acid (glutamic acid), and chlorogenic acids (CGA) as well as trigonelline contents. In this research, UV spectroscopy combined with chemometrics was used to classify a ground roasted Lampung robusta specialty coffee according to differences in the cherry processing methods. A total of 360 samples of Lampung robusta specialty coffee with 1 g of weight for each sample from three different cherry processing methods were prepared as samples: 100 samples of pure dry coffee (DRY), 100 samples of pure semi-dry coffee (SMD), 100 samples of pure wet coffee (WET) and 60 samples of adulterated coffee (ADT) (SMD coffee was adulterated with DRY and WET coffee). All samples were extracted using a standard protocol as explained by previous works. A low-cost benchtop UV-visible spectrometer (Genesys™ 10S UV-Vis, Thermo Scientific, Waltham, MA, USA) was utilized to obtain UV spectral data in the interval of 190–400 nm using the fast scanning mode. Using the first three principal components (PCs) with a total of 93% of explained variance, there was a clear separation between samples. The samples were clustered into four possible groups according to differences in cherry processing methods: dry, semi-dry, wet, and adulterated. Four supervised classification methods, partial least squares–discriminant analysis (PLS-DA), principal component analysis–linear discriminant analysis (PCA-LDA), linear discriminant analysis (LDA) and support vector machine classification (SVMC) were selected to classify the Lampung robusta specialty coffee according to differences in the cherry processing methods. PCA-LDA is the best classification method with 91.7% classification accuracy in prediction. PLS-DA, LDA and SVMC give an accuracy of 56.7%, 80.0% and 85.0%, respectively. The present research suggested that UV spectroscopy combining with chemometrics will be highly useful in Lampung robusta specialty coffee authentication.

Effect of Broken Coffee Beans Particle Size, Roasting Temperature, and Roasting Time on Quality of Coffee Beverage

Optimum flavor and aroma of the coffee are developed during the roasting process. However, certain problems exist in the coffee roasting process such as partial charring, over roasting, and poor temperature distribution across the coffee bean (due to the low thermal conductivity of bean), if conditions are not optimized. Hence, uniform temperature distribution across the coffee bean in the roasting process is highly desirable. To achieve these requirements, the broken coffee beans were positioned in a single layer packed bed arrangement using the closed system by circulating hot air. In this experiment, three factors were arranged in a completely randomized design with three levels and three replications. The first factor considered was roasting temperature (200°C, 230°C, and 260°C), second factor was roasting time (5 min, 10 min, and 15 min), and third was particle size (4–6 mm, 2.36–3.35 mm, and 1.7–2.36 mm). The initial moisture content of raw beans (cv. Limu) was determined. The data were collected on selective physical properties of roasted coffee beans and sensory acceptability of prepared beverage. The results showed that the physical properties and sensory acceptability are significantly high ( P < 0.001 ). It depends on the interaction effect of all the studied factors. Among the studies parameters, roasting temperature of 230°C with a particle size range of 4–6 mm showed the steady transition in dry mass loss and change in bulk density with increase in roasting duration. Coffee roasted at 230°C for 10 min with a particle size of 4–6 mm showed the highest sensory acceptability score (89.21). In conclusion, it can be said that a temperature of 230°C, a time of 10 min, and a particle size between 2.36–3.35 mm and 4–6 mm are recommended conditions for the roasting process of coffee beans.

Identification of markers of sensory quality in ground coffee: an untargeted metabolomics approach

IntroductionIn the last years, consumers increased the demand for high-quality and healthy beverages, including coffee. To date, among the techniques potentially available to determine the overall quality of coffee beverages, metabolomics is emerging as a valuable tool.ObjectiveIn this study, 47 ground coffee samples were selected during the 2018 Edition of the “International coffee tasting” (ICT) in order to provide discrimination based on both chemical and sensory profiles. In particular, 20 samples received a gold medal (“high quality” group), while lower sensory scores characterized 27 samples (without medal).MethodsUntargeted metabolomics based on ultra-high pressure liquid chromatography coupled with quadrupole-time-of-flight (UHPLC-QTOF) and head space-gas chromatography coupled with mass spectrometry platforms followed by multivariate statistical approaches (i.e., both supervised and unsupervised) were used to provide new insight into the searching of potential markers of sensory quality.ResultsSeveral compounds were identified, including polyphenols, alkaloids, diazines, and Maillard reaction products. Also, the headspace/GC-MS highlighted the most important volatile compounds. Polyphenols were scarcely correlated to the sensory parameters, whilst the OPLS-DA models built using typical coffee metabolites and volatile/Maillard compounds possessed prediction values > 0.7. The “high quality” group showed specific metabolomic signatures, thus corroborating the results from the sensory analysis. Overall, methyl pentanoate (ROC value = 0.78), 2-furfurylthiol (ROC value = 0.75), and L-Homoserine (ROC value = 0.74) established the higher number of significant (p < 0.05) correlations with the sensory parameters.ConclusionAlthough ad-hoc studies are advisable to further confirm the proposed markers, this study demonstrates the suitability of untargeted metabolomics for evaluating coffee quality and the potential correlations with the sensory attributes.Graphic abstract

Genetic and chemical control of coffee rust (Hemileia vastatrix Berk et Br.): impacts on coffee (Coffea arabica L.) quality.

The occurrence of diseases can alter coffee (Coffea arabica L.) metabolism, causing changes in the composition of coffee beans and beverage quality. However, little is known about which aspects of coffee quality are actually altered by rust (Hemileia vastatrix Berk et Br.) and by its main control methods. The effect of chemical and genetic methods for the control of coffee rust on the quality of coffee beans and beverage was investigated. Both genetic and chemical control reduce the damage caused by the disease in the composition of coffee beans. Genotypes with resistant ancestry, even with resistance breakdown, respond better to chemical control. The combination of genetic and chemical control favors an increase in the sugar content in the beans. Despite the fact that both genetic and chemical control are effective in reducing disease damage regarding the chemical composition of beans, the quality potential of Timor Hybrid genotypes associated with the cancellation of rust expression through the joint action of genetic and chemical control favors the composition of beans and, consequently, the quantitative assessment of sensory attributes, adding value to the final product. © 2020 Society of Chemical Industry.