Complexity of coffee flavor: A compositional and sensory perspective

Insight into how fermentation might contribute to the distinctiveness of Australian coffee

With a view to modulating the flavour profiles of Australian coffee, this investigation focused on three estates in New South Wales. Coffee cherries were processed into beans with wet fermented and non-fermented methods to evaluate the effects of fermentation and terroir on microbial population dynamics, volatile composition, and sensory properties. Thirty-three volatiles were quantified in green and roasted coffee beans - 12 esters, 9 alcohols, 6 acids, 3 monoterpenes, 2 norisoprenoids, 1 aldehyde - and 5 thiols were quantified in roasted coffee brews. Sensory descriptive analysis defined appearance, aroma, and flavour attributes to describe the coffee brews. Fermented coffees were characterised by increased intensity of 'black tea leaves' and 'dark chocolate' aromas and 'burnt toast' flavour. Results suggested that wet fermentation of Australian coffee cherries could enhance the content of some volatile compounds known to convey "floral" and "fruity" aromas commonly ascribed to premium coffees from traditional producing regions.

The high-resolution molecular portrait of coffee: A gateway to insights into its roasting chemistry and comprehensive authenticity profiles

The direct-infusion of 130 coffee samples into a Fourier-transform ion cyclotron mass spectrometer (FT-ICR-MS) provided an ultra-high resolution perspective on the molecular complexity of coffee: The exceptional resolving power and mass accuracy (± 0.2 ppm) facilitated the annotation of unambiguous molecular formulas to 11,500 mass signals. Utilizing this molecular diversity, we extracted hundreds of compound signals linked to the roasting process through guided Orthogonal Partial Least Squares (OPLS) analysis. Visualizations such as van Krevelen diagrams and Kendrick mass defect analysis provided deeper insights into the intrinsic compositional nature of these compounds and the complex chemistry underlying coffee roasting. Predictive OPLS-DA models established universal molecular profiles for rapid authentication of Coffea arabica versus Coffea canephora (Robusta) coffees. Compositional analysis revealed Robusta specific signals, indicative of tryptophan-conjugates of hydroxycinnamic acids. Complementary LC-ToF-MS2 confirmed their compound class, building blocks and structures. Their water-soluble nature allows for application across raw and roasted beans, as well as in ready-made coffee products.

Kluyveromyces lactis and Saccharomyces cerevisiae for Fermentation of Four Different Coffee Varieties

One strategy for adding unique characteristics and flavors to improve coffee quality is the selection of starter microorganisms. Here, we aimed to evaluate the effect of Saccharomyces cerevisiae LNFCA11 and Kluyveromyces lactis B10 as starter cultures on the quality of four different wet-fermented coffee varieties. Microbiological, molecular, and chemical analyses were carried out to identify yeast, bacteria, volatile compounds, carbohydrates and bioactive compounds in coffee. Sensory analysis was performed by Q-graders certified in coffee. Starter yeasts affected bioactive and volatile compounds as well as sensory descriptors in the coffee varieties. S. cerevisiae CA11 allowed a higher content of trigonelline and chlorogenic acid in MGS Paraíso 2 (P2) and Catuai Amarelo IAC62 (CA62) varieties. K. lactis B10 fermentation resulted in higher chlorogenic acid only on the P2 cultivar and MGS Catucaí Pioneira (CP). In addition, 5-methyl-2-furfuryl alcohol and n-hexadecanoic acid were produced exclusively by yeast fermentation compared to spontaneous fermentation. The coffee cultivars P2 presented more complex sensory descriptors and the attributes of aroma, acidity, and balance when fermented with S. cerevisiae CA11. Sensory descriptors such as lemongrass, citrus, and lemon with honey were related to K. lactis B10. Starter cultures allowed the coffees to be classified as specialty coffees. The fermentation showed that the choice of starter yeast depends on the desired sensory descriptors in the final product.

Effect of Temperature and Storage on Coffee's Volatile Compound Profile and Sensory Characteristics

The study investigated the effects of storage temperature, type of coffee, and brewing method on coffee's volatile compound profile and sensory quality. Three types of coffee were included in the study: Arabica, Robusta, and their 80/20 blend. Samples were stored at 5 °C and 20 °C for one month, after which the changes in the composition of volatile compounds were analysed and the sensory quality of espresso and cold brew coffee was assessed. The results showed that storing coffee at a lower temperature slows the changes in the profile of volatile compounds such as aldehydes, alcohols, pyrazines, and furans, helping preserve the desired aroma and flavour characteristics. Storage at higher temperatures resulted in greater changes in the volatile profile and sensory quality, with higher perceptions of earthy, sharp, and smoky notes and lower chocolatey and sweet notes. The brewing method also had a significant effect on the sensory quality. The espresso coffee had a higher intensity of coffee aroma, chocolate flavour, smoky aroma, and roasted notes. In contrast, cold brew coffee was perceived as sweeter, fruitier, and had more pronounced rum notes. The coffee type also significantly influenced the aroma and flavour profile. Arabica had a more harmonious and mild aromatic profile, while Robusta had a sharper aroma. The blend of Arabica and Robusta combined the characteristics of both coffees and offered a balanced aromatic profile.

The Growing Altitude Influences the Flavor Precursors, Sensory Characteristics and Cupping Quality of the Pu'er Coffee Bean

The growing altitude is an important factor affecting the quality of coffee. We explored the flavor precursors, sensory characteristics, and cupping qualities of coffee growing at different altitudes and discussed their associated relationships. The altitude at which coffee is grown has different effects on its chemical composition. Fatty acid contents increased with increasing altitudes, whereas alkaloid and chlorogenic acids contents decreased with increasing elevation. There was no obvious trend in either organic acids or monosaccharides. Eleven of the 112 detected volatile components were significantly affected by the growing altitude. The contents of pyrazines and alcohols tended to decrease, whereas those of aldehydes tended to increase. A significantly altered composition reduces the nutty and roasted flavors of coffee, while increasing the sweet sugar and caramel aromas. The aroma and flavor tended to increase with increasing altitudes during cupping, whereas the other indicators did not change significantly. The results provide a theoretical reference for the sales and promotion of Pu'er coffee.

Predicting best planting location and coffee cup quality from chemical parameters: An evaluation of raw Arabica coffee beans from São Paulo over two harvests

Arabica coffee is one of the most consumed beverages in the world. The chemical components present in raw Arabica coffee beans (RACB) are directly related to the cup quality of the beverage. Environmental and genetic factors influence the content and profile of these components. Then, this work aimed to evaluate different chemical parameters of RACB from 3 varieties planted in 3 different experimental farms located within the "Alta Mogiana" terroir harvested in 2021 and 2022 to identify a better variety for each farm to produce a high cup quality Arabica coffee. The harvest period had a strong influence on most of the studied parameters because atypical weather conditions occurred in the 2021 harvest. The RACB harvested in 2022 yielded better results and supposedly will produce a beverage of high cup quality. Samples harvested in this period presented mainly average moisture levels closer to optimum (11.02 against 8.56 % in 2021); low total titratable acidity (98.00 against 169.75 mL 0.1 M NaOH/100 g in 2021); high amounts of free amino acids (0.96 against 0.93 g GAE/100 g in 2021), low amounts of CGA (4.27 against 4.85 g/100 g in 2021) and caffeine (1.08 against 1.76 g/100 g in 2021) and high amounts of trigonelline (1.12 against 0.96 g/100 g in 2021). The Rome Sudan variety had the best combination of chemical results, mainly when cultivated in Farm 2 in 2022, presenting high amounts of protein content (15.24 %) and free amino acids (0.96 g GAE/100 g), low total titratable acidity (98.3 mL 0.1 M NaOH/100 g), low amounts of CGA (4.55 g/100 g) and caffeine (1.29 g/100 g) and high amounts of trigonelline (1.11 g/100 g). The analysis of chemical compounds could predict the best farm to cultivate each variety studied and was a guide to foresee a higher cup quality of RACB beverages.

Qualitative and Quantitative Sex-Related Differences in the Perception of Single Molecules from Coffee Headspace

One of the still-debated topics regarding the olfactory function concerns the presence or absence of sex-related differences in individuals. In this study, we checked for a relationship between the olfactory function of females and males and their ability to perceive single molecules, and researched how this can influence the intensity with which the complex odor formed by a set of single molecules is perceived. First, females and males were classified as normosmic or hyposmic based on the TDI olfactory score obtained using the Sniffin' Sticks test. Subsequently, the headspace of roasted coffee beans, as a complex olfactory stimulus, was broken down into single molecules by means of a chromatographic column; these were simultaneously conveyed to a mass spectrometer (for their subsequent classification) and to the human nose, which acts as a chemical sensor by means of an olfactometer port. The results obtained with this gas chromatography-olfactometry approach show both qualitative and quantitative differences between females and males, with females performing better than males. In addition, the odor intensity reported by females when sniffing pen #10, containing coffee aroma, is significantly higher than that reported by males. In conclusion, these data highlight that the human ability to perceive both single compounds and complex odors is strongly conditioned, not only by the olfactory function of individuals, but also by their sex.

Caffeic Acid: Numerous Chemoprotective Effects are Mediated via Hormesis

Caffeic acid is a common phenolic acid found in coffee and numerous fruits and vegetables. Known for its antioxidant properties, it is widely used as a dietary supplement as part of a polyphenol mixture or as an extract in the form of a capsule or powder. It is also available in liquid form as a homeopathic supplement. Caffeic acid phenethyl ester (CAPE) is an active component of propolis produced by honey bees. Propolis extract is used as a supplement and is available in various forms. The present paper is a comprehensive review of the biomedical literature, showing that caffeic acid effects are hormetic and occur in numerous biological models and cell types for a broad range of endpoints including many aging-related processes. Hormesis is a biphasic dose/concentration response displaying a low concentration/dose stimulation and a high concentration/dose inhibition. Complex alternative search strategies for caffeic acid were used since publications rarely used the terms hormesis or hormetic. Evaluation of the data provides the first assessment of caffeic acid-induced hormetic concentration/dose responses and their quantitative features. Their mechanistic foundations, extrapolative strengths/limitations, and their biomedical, clinical, and public health implications are discussed. Suggestions for future research are presented.

Comprehensive investigation of coffee acidity on eight different brewing methods through chemical analyses, sensory evaluation and statistical elaboration

Even if the acids composition and their role in coffee still need to be clarified, acidity is one of the main sought-after features in coffee and it is becoming one of the main quality markers. Hence, the aim of this paper was to evaluate the main parameters influencing coffee acidity with a focus on carboxylic acids. To the best of our knowledge, this is the first study regarding filter coffee prepared from specialty and mainstream coffee, differently roasted and through eight diverse extraction methods. Coffee cup chemical composition in terms of organic and chlorogenic acids, caffein and physicochemical parameters were correlated with perceived sourness and mouthfeel to better understand the influence of extracted compounds on the final beverage acidity. Statistical tools revealed that a major impact of chlorogenic acids emerged in pH and titratable acidity, while the sensorial sourness appeared more correlated with organic acids concentration. Thus, these findings suggests that organic acids could be potential predictors of beverage perceived acidity.

Optimization and validation of high throughput methods for the determination of 132 organic contaminants in green and roasted coffee using GC-QqQ-MS/MS and LC-QqQ-MS/MS

Recently some major safety concerns have been raised on organic contaminants in widely consumed plants such as coffee. Hence, this study aimed to develop specifically optimized methods for determining organic contaminants, such as pesticides and polychlorinated biphenyls (PCBs), in coffee using GC-MS/MS and LC-MS/MS. QuEChERS method was used as a base extraction method, and 27 experiments were studied using design of experiments with categorical variables (extraction buffers, cleanup sorbents, and coffee roasting degree) to find the optimum method for each matrix type. The optimum method for green coffee was acetate buffer and chitosan for clean-up, while no-buffer extraction and the PSA + C18 method were ideal for light and dark-roasted coffee. The optimized methods were validated in accordance with SANTE/11312/2021. Furthermore, ten real samples (4 green, and 6 roasted) from the markets were analysed; ortho-phenylphenol was found in all the roasted coffee samples, and carbendazim was found in one green coffee sample.

Evaluation of physical and chemical characteristics of bean and cup quality of arabica coffee genotypes grown in Southern Ethiopia

The study aimed to investigate physical characteristics, cup quality, and biochemical content variability among thirty South Ethiopian Arabica coffee genotypes over three locations. The results revealed the existence of statistically significant variation among genotype, location, and GEI effects for all studied traits. The overall coffee quality score for most of the tested genotypes in three locations was above 80 %. Therefore, in terms of quality, most of the tested genotypes can be used to produce specialty coffee in the study areas. A wider range of caffeine (0.52 % dwb to 1.53 % dwb) was recorded among the studied genotypes. Accordingly, the low caffeine contenting genotypes could be a promising candidate for the development of low caffeine varieties through selection and hybridization. Cluster analysis grouped genotypes into different clusters based on quality trait variation and similarity among genotypes. According to the PCA, caffeine content (0.35), chlorogenic acid (0.34), aromatic quality (0.31), trigonelline (0.29), acidity (0.28), astringency (0.28), color (0.27) in the first PCA, flavor (-0.48), and screen size (0.46) in the second PCA were the important variables contributing more to the variation, and these traits could be considered for effective parent selection in quality improvement programs. Genotype AW9648 achieved the highest score in overall quality attributes at all three locations and could be promoted as a promising candidate and best parent for hybridization in terms of quality. Hence, genotype by environment interaction was significant, the coffee quality improvement program should give due attention to incorporating genetic and environmental influences by using a multi-locational selection strategy.

Coffee and stress management: How does coffee affect the stress response?

This chapter explores the complex relationship between coffee drinking and stress management, highlighting the advantages and disadvantages of this widely consumed beverage. The chapter explores the physiological, psychological, and social effects of coffee on stress response and resilience through a thorough analysis of recent studies. It highlights the negative consequences of excessive intake on cardiovascular, gastrointestinal, and mental health while also discussing how moderate coffee consumption may lower stress levels, improve coping skills, and promote relaxation. Considerations for vulnerable populations, interactions with medications and supplements, and sustainability concerns in coffee production and consumption are also addressed. By identifying missing gaps in our understanding of coffee and stress management, the chapter underscores the need for future research to elucidate underlying mechanisms and promote mindful consumption practices. Ultimately, by embracing a holistic approach that considers individual health, environmental sustainability, and social responsibility, we can harness the potential of coffee to support resilience, well-being, and sustainability for individuals and communities worldwide.

Rapid classification of coffee origin by combining mass spectrometry analysis of coffee aroma with deep learning

Mislabeling the geographical origin of coffee is a prevalent form of fraud. In this study, a rapid, nondestructive, and high-throughput method combining mass spectrometry (MS) analysis and intelligence algorithms to classify coffee origin was developed. Specifically, volatile compounds in coffee aroma were detected using self-aspiration corona discharge ionization mass spectrometry (SACDI-MS), and the acquired MS data were processed using a customized deep learning algorithm to perform origin authentication automatically. To facilitate high-throughput analysis, an air curtain sampling device was designed and coupled with SACDI-MS to prevent volatile mixing and signal overlap. An accuracy of 99.78% was achieved in the classification of coffee samples from six origins at a throughput of 1 s per sample. The proposed approach may be effective in preventing coffee fraud owing to its straightforward operation, rapidity, and high accuracy and thus benefit consumers.

Steam distillation process for flavor enhancement of milk coffee: Effects of condensation temperature on volatile compounds and flavor characteristics

To enhance the flavor characteristics of milk coffee, steam distillation was applied to roasted ground coffee to obtain extracts that were then added to the hot water extract of the residue. The effects of different condensation temperatures for steam distillation on the volatile compounds of condensates and the flavor characteristics of the milk coffees prepared with each condensate were investigated. The volatile compounds were analyzed by gas chromatography/mass spectrometry, and principal component analysis (PCA) was performed on the mean peak areas of the volatiles that showed significant differences between the samples. The five types of milk coffees prepared with/without condensates were evaluated by consumer panelists using the check-all-that-apply question combined with the milk coffee flavor lexicon. The results showed that the concentration of volatile compounds tended to be higher in response to decreasing condensation temperature in steam distillation. The volatile compounds were grouped into four patterns based on their concentration in the condensates, which was affected by the volatility of the compounds and the duration of the condensation process in steam distillation. PCA clarified the characteristic volatile compounds that contribute to differences between the three condensates. The check-all-that-apply results indicated that the samples prepared with the condensates enhanced some specific coffee flavors, although acceptances for them were not enhanced. Implementing a steam distillation step in the milk coffee production process could lead to enhancing the coffee flavor strength of milk coffee products, and changing the condensation temperature for steam distillation was effective for providing different flavor characteristics of milk coffee. PRACTICAL APPLICATION: Changing the condensation temperature for steam distillation is effective in differentiating the flavor characteristics of milk coffee. Increasing the condensation temperature resulted in decreased concentrations of volatile compounds, which enhanced the milk and rich flavor. Decreasing the condensation temperature resulted in increased concentrations of volatile compounds, which provided a stronger coffee flavor to the milk coffee, possibly leading to a reduction in the use of coffee for milk coffee production. The check-all-that-apply question combined with the milk coffee flavor lexicon could effectively evaluate consumers' perceptions of the milk coffee flavor characteristics and their acceptances in a single survey.

Identification of antioxidant and flavour marker compounds in Kalosi-Enrekang Arabica brewed coffee processed using different postharvest treatment methods

This research aims to predict the presence of marker compounds that differentiate tubruk brew from coffee beans with different postharvest processing. This research also aims to predict compounds correlating with antioxidant activity and sensory flavour attributes. This research used Kalosi-Enrekang Arabica coffee beans, which were processed with three different postharvest processing (honey, full-washed and natural), roasted at medium level, and brewed using the tubruk method. Each brew was analyzed for chemical profiles using LC-MS and GC-MS, antioxidant analysis using the DPPH IC50 and FRAP methods, and sensory analysis for flavour using the QDA and SCAA methods for cupping scores. OPLS-DA analysis revealed the presence of marker compounds from each brew, and the dried fruit flavour attribute was to be an inter-process marker. After that, OPLS analysis showed marker compounds that correlate to antioxidant activity and flavour attributes. Rhaponticin is thought to be one of the marker compounds in natural coffee brews and is one of the compounds that correlates to the antioxidant activity of the DPPH method (IC50); prunin is thought to be one of the marker compounds for full-washed coffee brews and is one of the compounds that correlates to the activity antioxidants of FRAP method. Triacetin, which is thought to be a marker compound in natural brewed coffee, correlates with fruity flavour. 3-acetylpyridine, as a marker in honey-brewed coffee, correlates with nutty flavour. Even though there are differences in dominant flavours, the cupping score shows the brew is categorized as a specialty. This research shows that different post-harvest processing processes influence the compound profile, antioxidant activity and flavour attributes of Tubruk brewed coffee.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-05948-8.

Potential safety concerns of volatile constituents released from coffee-ground-blended single-use biodegradable drinking straws: A chemical space perspective

Incorporating spent coffee grounds into single-use drinking straws for enhanced biodegradability also raises safety concerns due to increased chemical complexity. Here, volatile organic compounds (VOCs) present in coffee ground straws (CGS), polylactic acid straws (PLAS), and polypropylene straws (PPS) were characterized using headspace - solid-phase microextraction and migration assays, by which 430 and 153 VOCs of 10 chemical categories were identified by gas chromatography - mass spectrometry, respectively. Further, the VOCs were assessed for potential genetic toxicity by quantitative structure-activity relationship profiling and estimated daily intake (EDI) calculation, revealing that the VOCs identified in the CGS generally triggered the most structural alerts of genetic toxicity, and the EDIs of 37.9% of which exceeded the threshold of 0.15 μg person-1 d-1, also outnumbering that of the PLAS and PPS. Finally, 14 VOCs were prioritized due to their definite hazards, and generally higher EDIs or detection frequencies in the CGS. Meanwhile, the probability of producing safer CGS was also illustrated. Moreover, it was uncovered by chemical space that the VOCs with higher risk potentials tended to gather in the region defined by the molecular descriptor related to electronegativity or octanol/water partition coefficient. Our results provided valuable references to improve the chemical safety of the CGS, to promote consumer health, and to advance the sustainable development of food contact materials.

Influence of divalent cations on the extraction of organic acids in coffee determined by GC-MS and NMR

The perceived flavor of coffee varies depending on the composition of the brewing water, and the influencing mechanisms are poorly understood. To investigate the effect of dissolved divalent cations on the extraction of organic acids in coffee, magnesium and calcium chloride salts were added pre- and post-brew. Citric, malic, lactic and quinic acid were analyzed using gas chromatography - mass spectrometry and nuclear magnetic resonance techniques. At concentrations typically found in drinking water, the salts resulted in limited variation of the acid content, while ten-fold higher salt concentrations produced more pronounced variations. Comparisons between pre- and post-brew additions showed similar acid content in most cases, suggesting that extraction of acids proceeds independent of the water composition. Interactions taking place post-brew may, however, influence the perceived flavor. A scientific basis for water quality recommendations in the coffee industry is long overdue and this work provides experimental and analytical contributions to continued research.

Functioning of Saccharomyces cerevisiae in honey coffee (Coffea canephora) and their effect on metabolites, volatiles and flavor profiles

Post-harvesting and microbial activity of coffee play a critical role in the metabolites and the sensory quality of the brew. The pulped natural/honey coffee process is an improvised semi-dry technique consisting of prolonged fermentation of depulped coffee beans excluding washing steps. The starter culture application in coffee industry plays an important role to enhance the cup quality. This work focuses on the fermentation of pulped natural/honey Robusta coffee with a starter culture (Saccharomyces cerevisiae MTCC 173) and the identification of fermentation patterns through 1H NMR, microbial ecology, volatomics and organoleptics of brew. Fermentation was accelerated by yeast populace (10 cfu log/mL) for 192 h. Principal compound analysis performed on 1H NMR led to the investigation of metabolites such as sugars, alkaloids, alcohols, organic acids and amino acids. Detection of some sugars and organic acids represented that the starter cultures imparted few metabolic changes during the process. A major activity of sugars in fermentation with 83.3 % variance in PC 1 and 16.7 % in PC 2 was observed. The chemical characteristics such as carbohydrates (41.88 ± 0.77 mg/g), polyphenols (34.16 ± 0.79 mg/g), proteins (58.54 ± 0.66 mg/g), caffeine (26.54 ± 0.06 mg/g), and CGA (21.83 ± 0.04 mg/g) were also evaluated. The heatmap-based visualization of GC-MS accorded characterization of additional 5 compounds in treated (T) coffee contributing to sweet, fruity and caramelly odor notes compared to untreated (UT). The sensory outlines 72.5 in T and 70.5 in UT scores. Preparation of honey coffee with Saccharomyces cerevisiae is the first report, which modulated the flavor and quality of coffee.

Electronic Prediction of Chemical Contaminants in Aroma of Brewed Roasted Coffee and Quantification of Acrylamide Levels

The aim of this research was to apply an electronic device as indirect predictive technology to evaluate toxic chemical compounds in roasted espresso coffee. Fresh coffee beans were subjected to different thermal treatments and analyzed to determine volatile organic compounds, content of acrylamide and 5-hydroxymethylfurfural, sensory characteristics and electronic nose data. In total, 70 different volatile compounds were detected and grouped into 15 chemical families. The greatest percentage of these compounds were furans, pyrazines, pyridines and aldehydes. The positive aroma detected had the intensity of coffee odor and a roasted aroma, whereas the negative aroma was related to a burnt smell. A linear relationship between the toxic substances and the sensory defect was established. A high sensory defect implied a lower content of acrylamide and a higher content of 5-hydroxymethylfurfural. Finally, electronic signals were also correlated with the sensory defect. This relationship allowed us to predict the presence of these contaminants in the roasted coffee beverage with an indirect method by using this electronic device. Thus, this device may be useful to indirectly evaluate the chemical contaminants in coffee beverages according to their sensory characteristics.

Genomic-assisted breeding for climate-smart coffee

Coffee is a universal beverage that drives a multi-industry market on a global basis. Today, the sustainability of coffee production is threatened by accelerated climate changes. In this work, we propose the implementation of genomic-assisted breeding for climate-smart coffee in Coffea canephora. This species is adapted to higher temperatures and is more resilient to biotic and abiotic stresses. After evaluating two populations, over multiple harvests, and under severe drought weather condition, we dissected the genetic architecture of yield, disease resistance, and quality-related traits. By integrating genome-wide association studies and diallel analyses, our contribution is four-fold: (i) we identified a set of molecular markers with major effects associated with disease resistance and post-harvest traits, while yield and plant architecture presented a polygenic background; (ii) we demonstrated the relevance of nonadditive gene actions and projected hybrid vigor when genotypes from different geographically botanical groups are crossed; (iii) we computed medium-to-large heritability values for most of the traits, representing potential for fast genetic progress; and (iv) we provided a first step toward implementing molecular breeding to accelerate improvements in C. canephora. Altogether, this work is a blueprint for how quantitative genetics and genomics can assist coffee breeding and support the supply chain in the face of the current global changes.

The Lipidic and Volatile Components of Coffee Pods and Capsules Packaged in an Alternative Multilayer Film

Coffee pods and capsules require packaging that guarantees the optimal coffee preservation. The chemical composition of coffee can undergo quality decay phenomena during storage, especially in terms of lipidic and volatile components. Amongst coffee packaging, aluminum multilayer materials are particularly widely diffused. However, aluminum is a negative component because it is not recoverable in a mixed plastic structure and its specific weight gives significant weight to packaging. In this study, a multilayer film with a reduced content of aluminum was used to package coffe pods and capsules and compared to a standard film with an aluminum layer. Their influence on the peroxides and volatile organic compounds of two coffee blends, 100% Coffea arabica L., 50% Coffea arabica L., and 50% Coffea canephora var. robusta L., were studied during their 180-day shelf life. The predominant volatile organic compounds detected belonged to the class of furans and pyrazines. Both packaging materials used for both coffee blends in the pods and capsules showed no significant differences during storage. Thus, the alternative packaging with less aluminum had the same performance as the standard with the advantage of being more sustainable, reducing the packaging weight, with benefits for transportation, and preserving the coffee aroma during the shelf life.

Antioxidant, antimicrobial and healing properties of an extract from coffee pulp for the development of a phytocosmetic

Consumer demand for natural, chemical-free products has grown. Food industry residues, like coffee pulp, rich in caffeine, chlorogenic acid and phenolic compounds, offer potential for pharmaceutical and cosmetic applications due to their antioxidant, anti-inflammatory, and antibacterial properties. Therefore, the objective of this work was to develop a phytocosmetic only with natural products containing coffee pulp extract as active pharmaceutical ingredient with antioxidant, antimicrobial and healing activity. Eight samples from Coffea arabica and Coffea canephora Pierre were analyzed for caffeine, chlorogenic acid, phenolic compounds, tannins, flavonoids, cytotoxicity, antibacterial activity, and healing potential. The Robusta IAC-extract had the greatest prominence with 192.92 μg/mL of chlorogenic acid, 58.98 ± 2.88 mg GAE/g sample in the FRAP test, 79.53 ± 5.61 mg GAE/g sample in the test of total phenolics, was not cytotoxic, and MIC 3 mg/mL against Staphylococcus aureus. This extract was incorporated into a stable formulation and preferred by 88% of volunteers. At last, a scratch assay exhibited the formulation promoted cell migration after 24 h, therefore, increased scratch retraction. In this way, it was possible to develop a phytocosmetic with the coffee pulp that showed desirable antioxidant, antimicrobial and healing properties.

A Systematic Analysis of the Correlation between Flavor Active Differential Metabolites and Multiple Bean Ripening Stages of Coffea arabica L

Coffee cherries contain a crucial flavor-precursor and chemical substances influencing roasted bean quality, yet limited knowledge exists on metabolite changes during cherry ripening. Our study identified 1078 metabolites, revealing 46 core differential metabolites using a KEGG pathway analysis. At the GF vs. ROF stage, amino acid synthesis dominated; ROF vs. BRF featured nucleotide catabolism; BRF vs. PRF exhibited glycoside and flavonoid synthesis; and PRF vs. PBF involved secondary metabolite synthesis and catabolism. The PRF stage emerged as the optimal cherry-harvesting period. A correlation analysis identified core differential metabolites strongly linked to taste indicators, suggesting their potential as taste markers. Notably, nucleotides and derivatives exhibited significant negative correlations with glycosides and flavonoids during ripening. This research systematically analyzed flavor and active substances in green coffee beans during cherry ripening, offering valuable insights into substance formation in Coffea arabica L.

Variables Affecting the Extraction of Antioxidants in Cold and Hot Brew Coffee: A Review

Coffee beans are a readily available, abundant source of antioxidants used worldwide. With the increasing interest in and consumption of coffee beverages globally, research into the production, preparation, and chemical profile of coffee has also increased in recent years. A wide range of variables such as roasting temperature, coffee grind size, brewing temperature, and brewing duration can have a significant impact on the extractable antioxidant content of coffee products. While there is no single standard method for measuring all of the antioxidants found in coffee, multiple methods which introduce the coffee product to a target molecule or reagent can be used to deduce the overall radical scavenging capacity. In this article, we profile the effect that many of these variables have on the quantifiable concentration of antioxidants found in both cold and hot brew coffee samples. Most protocols for cold brew coffee involve an immersion or steeping method where the coffee grounds are in contact with water at or below room temperature for several hours. Generally, a higher brewing temperature or longer brewing time yielded greater antioxidant activity. Most studies also found that a lower degree of coffee bean roast yielded greater antioxidant activity.

Revealing the dynamic changes of lipids in coffee beans during roasting based on UHPLC-QE-HR-AM/MS/MS

Coffee is popular worldwide and its consumption is increasing in recent years. Although mass spectrometry-based lipidomics approaches have been prevalent, their application in studies related to detailed information and dynamic changes in lipid composition during coffee bean roasting is still limited. The aim of this study was to investigate the dynamic changes in coffee bean lipids during the roasting process. The lipid classes and lipid molecular species in coffee beans were characterized by lipidomic analysis combined with chemometrics. A total of 12 lipid classes and 105 lipid molecular species were identified and quantified. Triacylglycerols (TAG) was the most abundant lipid class in both green beans and roasted beans. The content of phosphatidylethanolamine (PE) and lysophosphatidylethanolamine (LPE) in green beans was obviously higher than that in roasted beans. Other phospholipids, such as phosphatidylinositol (PI), lysophosphatidylinositol (LPI), phosphatidylcholine (PC), lysophophatidylcholine (LPC) and phosphatidic acid (PA), showed a tendency to increase at the beginning of roasting, then decreased gradually. Several differential lipid molecule species, for instance, PE (16:0_18:2), PC (18:2_18:2) were significantly down-regulated, and PI (18:1_18:2) was significantly up-regulated. This study provided a scientific basis for the change of coffee bean lipids during the roasting process.

Diterpenes stability of commercial blends of roasted and ground coffees packed in copolymer coupled with aluminium and eco-friendly capsules

Diterpenes are group of compounds of the terpenic fraction of roasted coffee and account for about 7-20 % (w/w) of the lipid fraction. Several parameters can influence their occurrence in coffee beans and beverages including species and post-harvest processing. Diterpenes in coffee have been studied extensively, but to the best of the authors' knowledge, there is no information in the literature on their stability over time. Coffee is a relatively stable product under optimal temperature, humidity and oxygen conditions. However, during storage it can undergo a series of chemical and physical reactions that alter its flavour and lead to rancidity, mainly due to the oxidative reactions that take place on the lipid fraction. In this study, the effect of long-term storage on the diterpene content of different commercial coffee blends and packaging is analysed and critically discussed. The Results show that the storage influences the internal environment of the capsules with an increase in moisture and a decrease in pH favouring more reactive conditions, especially for Eco capsules. Relative stability over time is observed for cafestol and kahweol. dehydro derivatives show a degradation up to T60 independently on the blends and packaging, which is not related to their precursors. The permeability of packaging and blends affect the modification of these components: while a drastic oxidation process takes place in Arabica eco compatible capsules (PC) when acidity and moisture increase, in Arabica/Robusta eco compatible capsules (IC) as well as in Arabica/Robusta and Arabica standard capsules (IS and PS) the peroxides tend to increase resulting in an autocatalytic propagation.

Evaluation of the behaviour of phenols and alkaloids in samples of roasted and ground coffee stored in different types of packaging: Implications for quality and shelf life

The most important factor in determining coffee quality and consumer choice is the flavour. During roasting, hundreds of simultaneous chemical reactions take place that contribute to the formation of the basic flavour of the coffee drink, imparting bitterness, astringency and acidity. The main chemical compounds responsible for these qualitative sensory properties are chlorogenic acids (CQAs), hydroxycinnamic acids and alkaloids. However, during storage, roasted and ground coffee can undergo several chemical and physical reactions that alter its flavour. This study focuses on LC-DAD analysis to investigate the effects of storing commercial coffee blends in different packaging, namely standard (multilayer film with aluminium barrier) and Eco-capsules. The results show relative stability of the phenolic and alkaloid fractions, although the CQA isomers behave differently and a decrease in caffeine and caffeic acid is observed during prolonged storage under 75% relative humidity compared to 65%, especially in Eco-friendly packaging.

Metabolomics as a tool for geographic origin assessment of roasted and green coffee beans

Coffee is widely consumed across the globe. The most sought out varieties are Arabica and Robusta which differ significantly in their aroma and taste. Furthermore, varieties cultivated in different regions are perceived to have distinct characteristics encouraging some producers to adopt the denomination of origin label. These differences arise from variations on metabolite content related to edaphoclimatic conditions and post-harvest management among other factors. Although sensory analysis is still standard for coffee brews, instrumental analysis of the roasted and green beans to assess the quality of the final product has been encouraged. Metabolomic profiling has risen as a promising approach not only for quality purposes but also for geographic origin assignment. Many techniques can be applied for sample analysis: chromatography, mass spectrometry, and NMR have been explored. The data collected is further sorted by multivariate analysis to identify similar characteristics among the samples, reduce dimensionality and/or even propose a model for predictive purposes. This review focuses on the evolution of metabolomic profiling for the geographic origin assessment of roasted and green coffee beans in the last 21 years, the techniques that are usually applied for sample analysis and also the most common approaches for the multivariate analysis of the collected data. The prospect of applying a wide range of analytical techniques is becoming an unbiased approach to determine the origin of different roasted and green coffee beans samples with great correlation. Predictive models worked accurately for the geographic assignment of unknown samples once the variety was known.

Identification of potential quality markers in Indonesia's Arabica specialty coffee using GC/MS-based metabolomics approach

INTRODUCTION

The cupping test is a widely used method for quality assessment of Arabica coffee. However, the cupping test is limited by the low number of certified panelists and the low throughput. Therefore, an analytical-based quality assessment may be a promising tool to complement the cupping test. A present, there is no report investigating quality marker candidates, focusing only on "specialty" grade Arabica coffee from Indonesia.

OBJECTIVE

This study identified the potential quality marker(s) in Arabica Specialty coffee at different stages (green beans, roasted beans, and brewed coffee.

METHODS

The metabolite profiles of ten different Arabica specialty-grade coffees were analyzed with different cup scores using gas chromatography-mass spectrometry (GC/MS). From the ten samples, green coffee beans, roasted coffee beans, and brewed coffee were selected. In addition, an orthogonal projection to latent structure (OPLS) regression analysis was conducted to obtain a potential quality marker based on the variable importance in projection (VIP). The potential quality marker(s) were validated by GC/MS metabolome profiling and OPLS analysis of different sets of samples consisting of 35 Arabica specialty-grade coffee samples.

RESULTS

In Arabica coffee samples, the OPLS model of the three stages showed galactinol to have a high VIP score. Galactinol showed a consistent positive correlation with cup scores at all stages of coffee production (green beans, roasted beans, and brewed coffee). The correlation suggests galactinol is a potential quality marker after further validation using different samples.

CONCLUSION

GC/MS combined with OPLS regression analysis suggested galactinol as a quality marker and provide an early screening method for Arabica coffee quality that complements the cupping test performed by certified panelists.

Discrimination of Filter Coffee Extraction Methods of a Medium Roasted Specialty Coffee Based on Volatile Profiles and Sensorial Traits

An untargeted gas chromatography-mass spectrometry (GC-MS) approach combined with sensory analysis was used to present the effects of different extraction methods (i.e., Pure Brew, V60, AeroPress, and French Press) on specialty graded Coffea arabica from Kenya. Partial Least Square Discriminant analysis and hierarchical clustering were applied as multivariate statistical tools in data analysis. The results showed good discrimination and a clear clustering of the groups of samples based on their volatile profiles. Similarities were found related to the filter material and shape used for the extraction. Samples extracted with paper filters (V60 and AeroPress) resulted in higher percentages of caramel-, and flowery-related compounds, while from metal filter samples (Pure Brew and French Press), more fruity and roasted coffees were obtained. Discriminant analysis allowed the identification of eight compounds with a high VIP (variable important in projection) discriminant value (i.e., >1), with 2-furanmethanol being the main feature in discrimination. Sensorial analyses were carried out through an expert panel test. The main evaluations revealed the French Press system as the lowest-scored sample in all the evaluated parameters, except for acidity, where its score was similar to V60. In conclusion, the data obtained from GC-MS analyses were in line with the sensorial results, confirming that the extraction process plays a fundamental role in the flavor profile of filter coffee beverages.

Application of GC-TOF/MS and GC×GC-TOF/MS to Discriminate Coffee Products in Three States (Bean, Powder, and Brew)

The volatiles in coffee play an important part in the overall flavor profile. In this study, GC-TOF/MS and GC×GC-TOF/MS were used to detect the volatile organic compounds (VOCs) in coffee samples of three different brands at three states (bean, powder, and brew). The differences between the two methods in characterizing VOCs were analyzed using the Venn diagram and PCA (principal component analysis). The important aroma-contributing compounds were further compared and analyzed. The results of the venn diagrams of different coffee samples showed that most VOCs existed in 2-3 kinds of coffee. The PCA of VOCs in different coffee samples showed that the VOCs detected by GC-TOF/MS could distinguish the coffee samples in the different states. GC×GC-TOF/MS was suitable for the further identification and differentiation of the different brands of coffee samples. In addition, pyridine, pyrrole, alcohols, and phenols greatly contributed to distinguishing coffee in three states, and alcohols greatly contributed to distinguishing the three brands of coffee.

Interaction and Metabolic Function of Microbiota during the Washed Processing of Coffea arabica

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.

Coffee bean processing: Emerging methods and their effects on chemical, biological and sensory properties

Emerging processing methods have been applied in coffee bean processing for improved sensory quality. The processes focus on optimizing the fermentation process of the coffee cherries and beans. This involves various pathways, including the formation of volatiles, flavor precursors and organic acids and the reduction in the concentrations of bioactive compounds. Comprehensive information regarding the effect of these emerging processes on the chemical, biological and sensory properties of the coffee beans is summarized. Emerging processes affected the coffee bean to various degrees depending on the raw material and the method used. The emerging methods promoted the reduction of bioactives such as caffeine and phenolics in coffee beans. Substantial improvement of these processes is needed to obtain coffee beans with improved biological activities. Effort to simplify the methods and optimize the post-fermentation process is crucial for the methods to be easily accessible by the producers and to produce defect-free coffee beans.

Optimizing drip fertigation at different periods to improve yield, volatile compounds and cup quality of Arabica coffee

How to improve and regulate coffee bean yield and quality through split fertilization in the whole life cycle of coffee is still unclear and deserves further study. A field experiment of 5-year-old Arabica coffee trees was conducted for 2 consecutive years from 2020 to 2022. The fertilizer (750 kg ha^-1 year^-1, N-P₂O₅-K₂O:20%-20%-20%) was split in three times at early flowering (FL), the berry expansion (BE), and the berry ripening (BR). Taking equal fertilization throughout the growth cycle (FL₂₅₀BE₂₅₀BR₂₅₀) as the control check, variable fertilizations including FL₁₅₀BE₂₅₀BR₃₅₀, FL₁₅₀BE₃₅₀BR₂₅₀, FL₂₅₀BE₁₅₀BR₃₅₀, FL₂₅₀BE₃₅₀BR₁₅₀, FL₃₅₀BE₁₅₀BR₂₅₀, and FL₃₅₀BE₂₅₀BR₁₅₀. Leaf net photosynthetic rate (A _net), stomatal conductance (g _s), transpiration rate (T _r), leaf water use efficiency (LWUE), carboxylation efficiency (CE), partial factor productivity of fertilizer (PFP), bean yield, crop water use efficiency (WUE), bean nutrients, volatile compounds and cup quality, and the correlation of nutrients with volatile compounds and cup quality was evaluated. FL₃₅₀BE₂₅₀BR₁₅₀ had the maximum A _net and g _s, followed by FL₂₅₀BE₃₅₀BR₁₅₀. The highest dry bean yield and WUE were obtained from FL₂₅₀BE₃₅₀BR₁₅₀, which increased by 8.86% and 8.47% compared with FL₂₅₀BE₂₅₀BR₂₅₀ in two-year average. The ash, total sugar, fat, protein, caffeine and chlorogenic acid in FL₂₅₀BE₃₅₀BR₁₅₀ were 6.47%, 9.48%, 3.60%, 14.02%, 4.85% and 15.42% higher than FL₂₅₀BE₂₅₀BR₂₅₀. Cluster analysis indicated FL₁₅₀BE₃₅₀BR₂₅₀, FL₂₅₀BE₃₅₀BR₁₅₀, FL₃₅₀BE₁₅₀BR₂₅₀ and FL₃₅₀BE₂₅₀BR₁₅₀ under medium roasted degree increased pyrazines, esters, ketones and furans, FL₁₅₀BE₃₅₀BR₂₅₀ and FL₂₅₀BE₃₅₀BR₁₅₀ under dark roasted degree increased ketones and furans. The aroma, flavor, acidity and overall score of medium roasted coffee were higher than dark roasted coffee, while the body score of dark roasted coffee was higher than medium roasted coffee. The nutrient contents were correlated with the volatile compounds and cup quality. TOPSIS indicated that FL₂₅₀BE₃₅₀BR₁₅₀ was the optimal fertilization mode in the xerothermic regions. The obtained optimum fertilization mode can provide a scientific basis for coffee fertilization optimization and management.

The effect of post-brew holding time and carafe type on the sensory properties of drip brew coffee

BACKGROUND

Coffee quality is believed to degrade quickly after brewing, and retail establishments discard unsold brewed coffee after a specified holding time period, sometimes as short as 30 min. We used trained sensory panels to evaluate the flavor profiles of light, medium, and dark roast coffees held in three different carafe types (glass on hot plate, thermal jacket, and vacuum insulated) for times ranging from 15 min to 3 h. Furthermore, a panel of 93 coffee-industry professionals performed a blind evaluation of fresh (30 min) versus held (180 min) coffee for overall liking and attribute level adequacy.

RESULTS

Sourness increased over time, consistent with acidity increasing over time (i.e., higher titratable acidity, lower pH), but only for the light and medium roasts. Dark roasted coffee became significantly more acidic over 3 h post-brew but was not perceived as more sour over time by the sensory panel. Variations were observed between the thermal jacket and vacuum carafes for the light and dark roast, but few differences were observed with storage type in the medium roast. Surprisingly, the panel of coffee industry professionals showed no preference for fresh over held.

CONCLUSIONS

More sensory attributes decreased than increased over time, suggesting that the primary concern with loss of quality during coffee holding may be the loss of volatile aroma compounds. Hedonic ratings suggest that even if the changes over time are noticeable, they may not negatively impact overall liking. © 2022 Society of Chemical Industry.

The Use of Carbon Dioxide as a Green Approach to Recover Bioactive Compounds from Spent Coffee Grounds

Spent coffee grounds (SCG) contain bioactive compounds. In this work, given the increasing demand to valorize waste and use green technologies, SCG were submitted to extraction by carbon dioxide (CO2) in supercritical and liquid conditions. The extraction parameters were varied to obtain the maximum yield with the maximum antioxidant activity. The use of supercritical and liquid CO2 with 5% ethanol for 1 h provided yields (15 and 16%, respectively) comparable to those obtained by control methods for 5 h and extracts with high total polyphenolic contents (970 and 857 mg GAE/100 g oil, respectively). It also provided extracts with DPPH (3089 and 3136 μmol TE/100 g oil, respectively) and FRAP (4383 and 4324 μmol TE/100 g oil, respectively) antioxidant activity levels higher than those of hexane extracts (372 and 2758 μmol TE/100 g oil, respectively) and comparable to those of ethanol (3492 and 4408 μmol TE/100 g oil, respectively). The SCG extracts exhibited linoleic, palmitic, oleic, and stearic acids (predominant fatty acids) and furans and phenols (predominant volatile organic compounds). They were also characterized by caffeine and individual phenolic acids (chlorogenic, caffeic, ferulic, and 3,4-dihydroxybenzoic acids) with well-known antioxidant and antimicrobial properties; therefore, they could be used in the cosmetic, pharmaceutical, and food sectors.

Using ground coffee particle size and distribution to remodel beverage properties

This study examined the influence of ground coffee granulometry and particle distribution on extraction parameters. They have been investigated the physicochemical properties, and the bioactive and volatile compound content in coffee obtained by a conventional filter method, the French Press, as a function of particle size and distribution. Some samples have been used for the extraction the directly the grinding machine, set at different grinding grade, and other samples have been seed before the usage in order to reproduce samples at different particle size class very homogeneous. The results showed that bioactive and volatile compounds are released differently in the beverages depending on the specific particle size. The results have been demonstrated that a homogeneous grind was more deficient in bioactive compounds and total dissolved solids than a classical, bimodal grind. Moreover, extraction from a very fine homogeneous grind was poorest with respect to these compounds, despite the greater surface in contact with the solvent. Conversely, bimodal grinds obtained conventional by the grinding machine, which were more heterogeneous from a granulometric point of view, were found to be richer in volatile organic and bioactive compounds. The study highlights that the grind plays a key role in producing well-extracted coffee and, therefore, in making the most of the potential inherent in the roasted bean.

Ecological quality as a coffee quality enhancer. A review

As both coffee quality and sustainability become increasingly important, there is growing interest in understanding how ecological quality affects coffee quality. Here we analyze, for the first time, the state of evidence that ecological quality, in terms of biodiversity and ecosystem functions, impacts the quality of Coffea arabica and C. canephora, based on 78 studies. The following ecosystem functions were included: pollination; weed, disease, and pest control; water and soil fertility regulation. Biodiversity was described by the presence, percentage, and diversity of shade trees. Coffee quality was described by the green bean physical characteristics, biochemical compounds, and organoleptic characteristics. The presence and diversity of shade trees positively impacted bean size and weight and reduced the percentage of rejected beans, but these observations were not consistent over different altitudes. In fact, little is known about the diversity of shade trees and their influence on biochemical compounds. All biochemical compounds varied with the presence of shade, percentage of shade, and elevation. Coffee beans from more diverse tree shade plantations obtained higher scores for final total organoleptic quality than simplified tree shade and unshaded plantations. Decreasing ecological quality diminished ecosystem functions such as pollination, which in turn negatively affected bean quality. Shade affected pests and diseases in different ways, but weeds were reduced. High soil quality positively affected coffee quality. Shade improved the water use efficiency, such that coffee plants were not water stressed and coffee quality was improved. While knowledge on the influence of shade trees on overall coffee quality remains scarce, there is evidence that agroecosystem simplification is negatively correlated with coffee quality. Given global concerns about biodiversity and habitat loss, we recommend that the overall definition of coffee quality include measures of ecological quality, although these aspects are not always detectable in certain coffee quality characteristics or the final cup.

Detection of Markers in Green Beans and Roasted Beans of Kalosi-Enrekang Arabica Coffee with Different Postharvest Processing Using LC-MS/MS

Our study is aimed at evaluating the effect of postharvest processing (natural, honey, and fully washed) on the compounds profile in green beans and roasted beans of Kalosi-Enrekang Arabica coffee and determining the marker compounds for each process. These beans were extracted using boiling water, and the extract was analyzed using LC-MS/MS. The results of this work confirmed the significant impact of postharvest processing on compounds in the coffee beans, and each process has a marker compound. Green beans by natural processing have 3 marker compounds, honey processing has 6 marker compounds, and fully washed processing has 2 marker compounds. Meanwhile, roasted beans by natural processing have 4 marker compounds, honey processing has 5 marker compounds, and fully washed processing has 7 marker compounds. In addition, our research identified caffeoyl tyrosine in green beans from natural and honey processing, which was previously only identified in Robusta coffee. These marker compounds can differentiate postharvest processing (natural, honey, and fully washed). These results can also help understand the effect of postharvest processing on the chemical composition of green and roasted beans.

Potential Aroma Chemical Fingerprint of Oxidised Coffee Note by HS-SPME-GC-MS and Machine Learning

This study examines the volatilome of good and oxidised coffee samples from two commercial coffee species (i.e., Coffea arabica (arabica) and Coffea canephora (robusta)) in different packagings (i.e., standard with aluminium barrier and Eco-caps) to define a fingerprint potentially describing their oxidised note, independently of origin and packaging. The study was carried out using HS-SPME-GC-MS/FPD in conjunction with a machine learning data processing. PCA and PLS-DA were used to extrapolate 25 volatiles (out of 147) indicative of oxidised coffees, and their behaviour was compared with literature data and critically discussed. An increase in four volatiles was observed in all oxidised samples tested, albeit to varying degrees depending on the blend and packaging: acetic and propionic acids (pungent, acidic, rancid), 1-H-pyrrole-2-carboxaldehyde (musty), and 5-(hydroxymethyl)-dihydro-2(3H)-furanone.

Effect of Three Post-Harvest Methods at Different Altitudes on the Organoleptic Quality of C. canephora Coffee

C. canephora (syn. C. robusta) is distinctive due to its rising industrial value and pathogen resistance. Both altitude and post-harvest methods influence coffee cup quality; however, modest information is known about this coffee species. Therefore, the aim of this study was to determine the relationship between four different altitudes and post-harvest processes (dry, honey, and wet) to the improvement of the organoleptic quality of the C. canephora congolensis and conilon drink. For dry processing, congolensis and conilon showed the lowest scores in terms of fragrance/aroma, flavour, aftertaste, salt–acid, bitter–sweet, and body. Above 625 m, coffees from dry, honey, and wet processes increased scores in their sensory attributes, but there was no difference at such high altitudes when comparing post-harvest samples. Dry-processed coffee samples had total scores over 80 points at high altitudes. Conilon was perceived to have the best sensory attributes at high altitudes using honey processing. In general, the wet-processed congolensis and conilon samples had a tastier profile than dry-processed ones.

Unraveling the impact of the capsule material on the aroma of brewed coffee by headspace analysis using a HiSorb probe followed by reverse fill/flush flow modulation GC×GC-MS

The present paper discusses the use of a high-concentration-capacity tool, HiSorb, to investigate the impact of capsule material on the aroma profile of espresso-brewed coffee. The specific high-concentration-capacity probe used is characterized by a sorbent volume (63 μL) intermediate between the solid-phase microextraction (SPME) fiber (0.6 μL) and the stir-bar sorptive extraction rod (126 μL). The extraction performance of the HiSorb was compared, in terms of both absolute signal and compound coverage, with both an equivalent sorbent (polydimethylsiloxane) and a divinylbenzene/carboxen/polydimethylsiloxane SPME fiber using both targeted and untargeted approaches. The HiSorb showed superior extraction compared with the SPME fibers. The HiSorb was then optimized in terms of extraction time and temperature and used to investigate the volatile profile of 23 espresso-brewed coffees prepared with capsules made of different materials-aluminum, compostable, and aluminum multilayer pack-prepared using a refillable capsule. Comprehensive two-dimensional gas chromatography equipped with a reverse fill/flush flow modulator and coupled to mass spectrometry was used to obtain a chromatographic fingerprint of the volatile profile of the brewed coffee. The data were aligned and compared using a tile-based approach, and the results were obtained by performing raw data mining within the same software platform. The data mining enabled the extraction of informative features responsible for the differentiation between the different capsule materials, showing a significant depletion in aroma intensity in the compostable capsule.

How to Identify Roast Defects in Coffee Beans Based on the Volatile Compound Profile

The aim of this study was to detect and identify the volatile compounds in coffee that was obtained in defect roast processes versus standard roasting and to determine the type and strength of the correlations between the roast defects and the volatile compound profile in roasted coffee beans. In order to achieve this goal, the process of coffee bean roasting was set to produce an underdeveloped coffee defect, an overdeveloped coffee defect, and defectless coffee. The "Typica" variety of Arabica coffee beans was used in this study. The study material originated from a plantation that is located at an altitude of 1400-2000 m a.s.l. in Huehuetenango Department, Guatemala. The analyses were carried out with the use of gas chromatography/mass spectrometry (GC-MS) and an electronic nose. This study revealed a correlation between the identified groups of volatile compounds and the following coffee roasting parameters: the time to the first crack, the drying time, and the mean temperatures of the coffee beans and the heating air. The electronic nose helped to identify the roast defects.