Search Results (103)

Coffee is one of the most widely consumed beverages worldwide, primarily due to the stimulating effects attributed to its caffeine content. However, excessive intake of caffeine results in negative effects, including palpitations, anxiety, and insomnia. Therefore, low-caffeine coffee has captivated growing consumer interest, highlighting its significant market potential. Traditional decaffeination methods often lead to non-selective extraction, resulting in a loss of desirable flavor compounds, thereby compromising coffee quality. In recent years, microbial fermentation has emerged as a promising, targeted, and safe approach for reducing caffeine content during processing. Additionally, mixed-culture fermentation further enhances coffee flavor and overcomes the drawbacks of monoculture fermentation, such as low efficiency and limited flavor profiles. Nonetheless, several challenges are yet to be resolved, including microbial tolerance to caffeine and related alkaloids, the safety of fermentation products, and elucidation of the underlying mechanisms behind microbial synergy in co-cultures. This review outlines the variety of microorganisms with the potential to degrade caffeine and the biochemical processes involved in this process. It explores how microbes tolerate caffeine, the safety of metabolites produced during fermentation, and the synergistic effects of mixed microbial cultures on the modulation of coffee flavor compounds, including esters and carbonyls. Future directions are discussed, including the screening of alkaloid-tolerant strains, constructing microbial consortia for simultaneous caffeine degradation for flavor enhancement, and developing high-quality low-caffeine coffee. Full article

Spent coffee grounds are the most abundant waste generated during the preparation of coffee beverages, amounting to 60 million tons per year worldwide. Excessive food waste production has become a global issue, emphasizing the need for waste valorization through the bioprocess of solid-state fermentation (SSF) for high added-value compounds. This work aims to identify the operational conditions for optimizing the solid-state fermentation process of spent coffee grounds to recover bioactive compounds (as polyphenols). An SSF process was performed using two filamentous fungi (Trichoderma harzianum and Rhizopus oryzae). An exploratory design based on the Hunter & Hunter method was applied to analyze the effects of key parameters such as inoculum size (spores/mL), humidity (%), and temperature (°C). Subsequently, a Box–Behnken experimental design was carried out to recovery of total polyphenols. DPPH, ABTS, and FRAP assays evaluated antioxidant activity. The maximum concentration of polyphenols was observed in treatment T3 (0.279 ± 0.002 TPC mg/g SCG) using T. harzianum, and a similar result was obtained with R. oryzae in the same treatment (0.250 ± 0.011 TPC mg/g SCG). In the Box–Behnken design, the most efficient treatment for T. harzianum was T12 (0.511 ± 0.017 TPC mg/g SCG), and for R. oryzae, T9 (0.636 ± 0.003 TPC mg/g SCG). These extracts could have applications in the food industry to improve preservation and functionality. Full article

Post-harvest processing (PHP) is a key determinant of coffee quality, flavor profile, and market classification, yet verifying PHP claims remains a significant challenge in the specialty coffee industry. This study introduces near-infrared spectroscopy (NIRS) coupled with chemometrics as a rapid, non-destructive approach to classify green coffee beans based on PHP. For the first time, seven distinct PHP categories—Alchemy, Anaerobic Processing (Deep Fermentation), Dry-Hulled, Honey, Natural, Washed, and Wet-Hulled—were discriminated using NIRS, encompassing 20 different processing protocols under varying environmental and fermentation conditions. The NIR spectra (350–2500 nm) of 524 green Arabica coffee samples were analyzed using PCA-LDA models (750–2450 nm), achieving classification accuracies up to 100% for underrepresented categories and strong performance (91–95%) for dominant PHP groups in an independent test set. These results demonstrate that NIRS can detect subtle chemical signatures associated with diverse PHP techniques, offering a scalable tool for quality assurance, fraud prevention, and traceability in global coffee supply chains. While limited sample sizes for some PHP categories may influence model generalization, this study lays the foundation for future work involving broader datasets and integration with digital traceability systems. The approach has direct implications for producers, traders, and certifying bodies seeking reliable, real-time PHP verification. Full article

Novel methods of coffee processing, including animal-assisted fermentation, are gaining popularity—among them, elephant dung coffee stands out for its rarity and high price, making it a likely target for adulteration. This study aims to discover candidate biomarkers for elephant coffee by comparing the chemical composition, antioxidant activity, and volatile profiles of Arabica coffee processed by three methods: conventional, civet-derived, and elephant-derived (all originated from Southeast Asia, medium roast). Analytical methods included HPLC-UV and GC-SPME-MS, along with in vitro antioxidant assays (DPPH, ORAC, ABTS, total phenolics, and total flavonoids). Principal Component Analysis (PCA) was used to evaluate differences between the samples. While elephant coffee showed lower caffeine (0.93%) and antioxidant capacity across all assays, it was richer in selected volatile compounds, such as pyrazines (e.g., 3-ethyl-2,5-dimethylpyrazine; 3.73% RPA), 2- and 3-methybutanal (1.18 and 0.19% RPA), and furfuryl acetate (18.00% RPA; p < 0.05). These changes are likely to be due to fermentation in the gastrointestinal tract. Despite differences, no definitive biomarker of elephant coffee was found, suggesting that discrimination from other coffee samples may not be as simple as previous studies indicated. More studies with a higher number of samples that employ an extensive analytical approach (e.g., omics or NMR) to thoroughly analyze the phytochemical profile of coffee beans before and after digestion by the elephant are needed. Full article

Volcanic fermentation is an innovative technique in post-harvest coffee processing that involves forming conical mounds, called “volcanoes”, to create specific biotransformation conditions. This study investigates the impact of different volcano fermentation methods on the chemical composition and sensory attributes of coffee. Four methods were evaluated: asphalt patio (E1), on pallets (E2), in steel containers under the sun (E3), and in steel containers in the shade (E4). The chemical composition was analyzed in terms of sugars (sucrose, glucose, fructose), organic acids (citric, malic, succinic, lactic, acetic) and alcohols (glycerol, ethanol). In addition, color differences (ΔE) and sensory analysis of the fermented coffees were evaluated. The results of this study reveal that volcanic fermentation produces high-quality specialty coffees, but with divergent profiles of acids and alcohols, thus influencing the sensory characteristics of the resulting beverage. However, the different methods of volcanic fermentation did not significantly affect pH and soluble solids, indicating that the microbiota developed an efficient and consistent fermentation regardless of the solar exposure conditions. The most frequently mentioned sensory descriptors were chocolate, citrus fruits, honey/molasses, caramel, floral, and brown sugar. These findings highlight the significant influence of the volcanic fermentation method on the chemical and sensory quality of coffee fermented. Full article

Submerged fermentation offers a controlled environment for coffee processing, ensuring a consistent temperature and aerobic–anaerobic conditions, making it a superior alternative to solid-state fermentation. This study aimed to optimize submerged fermentation conditions for green coffee beans to maximize total phenolic content (TPC) and antioxidant activity, such as ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), DPPH (2,2-Diphenyl-1-picrylhydrazyl), and FRAP (the ferric reducing antioxidant power). Additionally, pH, yeast, and lactic acid bacteria counts were monitored. Fermentation was conducted with selective microbial starters, a varying temperature (25–35 °C), incubation time (3–9 days), and coffee weight (5–10 g) using a Box–Behnken design. To enhance bioactive compound infusion, fresh coffee cherries underwent ultrasonic treatment, increasing their porosity and water-holding capacity. Vacuum impregnation was then used to infuse fermented green coffee bean extract into the cherries. The lowest pH coincided with peak yeast growth, while the coffee weight significantly influenced all responses. The incubation time affected most parameters except DPPH activity, and the temperature impacted only ABTS and DPPH activities. Optimal conditions (35 °C; 7.21 days; 10 g) yielded a TPC of 480.25 µmol GAE/100 g with ABTS, DPPH, and FRAP activities of 725.71, 164.15 and 443.60 µmol TE/g, respectively. Ultrasound-treated coffee cherries exhibited increased porosity and absorption capacity, facilitating enhanced bioactive compound infusion during 3 h of vacuum impregnation. In conclusion, submerged fermentation effectively improves bioactive compound production, while ultrasound treatment and vacuum impregnation present promising methods for developing high-value dehydrated coffee cherry products. Full article

Coffee quality can be modified with microorganism addition during post-harvest processing. While most studies focus on yeasts and lactic acid bacteria, other species identified in the digestive tract of palm civets might also contribute to the quality of luwak coffee. Bacteria akin to those identified in palm civets’ gastrointestinal tract or feces were evaluated for their potential to modify coffee bean composition. Among those, Bacillus subtilis ATCC 6633, Gluconobacter sp. KKP 3751 and Lactiplantibacillus plantarum ATCC 4080 exhibited strong growth in green coffee extract. The use of these bacteria significantly changed the amounts of basic coffee components (taste and aroma precursors), and slightly altered bioactive compound levels in green and roasted beans. The influence of fermentation duration was evaluated using L. plantarum. A stationary growth phase and positive changes regarding phenolic content were achieved after 24 h of fermentation. Overall, the use of bacteria can influence bean composition, offering the potential to create unique coffee products. Full article

To investigate the metabolic differences and mechanisms during the fermentation process of coffee-grounds craft beer, HS-SPME-GC/MS untargeted metabolomics technology was used to study the metabolic differences during the fermentation process of coffee-grounds craft beer. Multivariate statistical analysis and pathway analysis were combined to screen for significantly different metabolites with variable weight values of VIP ≥ 1 and p < 0.05. The results indicate that at time points T7, T14, T21, and T28, a total of 183 differential metabolites were detected during the four fermentation days, with 86 metabolites showing significant differences. Its content composition is mainly composed of lipids and lipid-like molecules, organic oxygen compounds, and benzoids, accounting for 63.64% of the total differential metabolites. KEGG enrichment analysis of differentially expressed metabolites showed a total of 35 metabolic pathways. The top 20 metabolic pathways were screened based on the corrected p-value, and the significantly differentially expressed metabolites were mainly enriched in pathways such as protein digestion and absorption, glycosaminoglycan biosynthesis heparan sulfate/heparin, and benzoxazinoid biosynthesis. The different metabolic mechanisms during the fermentation process of coffee-grounds craft beer reveal the quality changes during the fermentation process, providing theoretical basis for improving the quality of coffee-grounds craft beer and having important theoretical and practical significance for improving the quality evaluation system of coffee-grounds craft beer. Full article

Orange peel represents 50% of the fruit, and more than 124 million tons are consumed worldwide, which represents a worrying contamination problem. This study sought to add this waste as flour in coffee fermentation to enhance the process. Since this is a new alternative in the processing of coffee beans, the study focused on modelling the reducing sugars of coffee fermentation by adding citrus waste to relate artificial intelligence to the practical application of using waste in production processes. Standardised analyses were performed regarding pH (4.86 ± 0.05), humidity (8.17 ± 0.74%), ash content (4 ± 0.03%), and reducing sugars (20.23 ± 0.20 mg/mL), and orange peel flour was added to coffee beans at concentrations of 0, 2, 4, and 6% for solid-state fermentation. The results indicate that the 2% concentration accelerated fermentation times, increased reducing sugars, and maintained favourable sensory qualities in the coffee (flavour profile of delicate fruity and floral notes). Artificial neural networks revealed a strong overall correlation (R² = 0.866) between pH changes and sugar concentrations throughout the process. This research highlights the potential of utilizing orange peel flour to enhance coffee fermentation, supporting further investigation into their application across various stages of coffee processing to maximise overall quality and environmental benefits. Full article

This study developed an inoculum culture for semi-controlled coffee fermentation using lactic acid bacteria (LAB) and yeast, with coffee production by-products as carbon sources. The viability of the inoculum was optimized by using a mixture design to vary the proportions of coffee pulp (CP) and wastewater (CWW) in 0.25 increments; as a process variable, fermentation time ranged from 36 to 48 h for LAB and 12 to 36 h for yeast. Soluble solids (SS), pH, and titratable acidity (TA) were monitored, and the response variable was the variation in microbial viability. The optimized inoculums were used for coffee fermentation alone and in combination, and fermentation parameters and sensory evaluation were measured. The optimal by-product combination for LAB inoculum was 100% CP, with a 48 h fermentation, reaching a maximum of 7.8 × 10⁷ CFU/mL. The optimal formulation for yeast was 100% CWW for 36 h, achieving a maximum concentration of 8.3 × 10⁸ CFU/mL. Experimental results for both inoculums were fit to a quadratic statistical model with R² of 0.84 and 0.88 and Adj-R² of 0.77 and 0.83 for LAB and yeast, respectively. The optimized inoculums produced high sensory scores, particularly in balance, fragrance, and acidity. Using mixed inoculums, we achieved the highest fragrance/aroma score (8.25) and an improved balance, attributed to higher TA and lower pH, which are linked to enhanced flavor complexity. This demonstrates that by-product-based inoculums can not only increase microbial viability but also improve the sensory quality of coffee, supporting sustainable practices in coffee processing. Full article

The market for probiotic foods has grown significantly in recent years. Some microorganisms isolated from food fermentations, mainly lactic acid bacteria (LAB) and yeasts, may have probiotic potential. During the fermentation of cocoa and coffee, a plethora of microorganisms are involved, including yeasts and lactic acid bacteria (LAB), several of which may have probiotic potential. For this reason, this study aimed to overview the probiotic potential of some LAB and yeasts isolated from these fermentation processes. For this purpose, a search was conducted in several specialized databases (Google Scholar, PubMed, ScienceDirect, and Scopus). As a result of this search, some strains of LAB and yeasts from cocoa were found to be potentially probiotic, with characteristics like those of commercial probiotic strains. The LAB genera that showed the most substantial probiotic potential were Lactiplantibacillus, Limosilactobacillus, and Lactococcus, while for yeasts, it was Saccharomyces and Pichia. Full article

The coffee industry, while processing coffee beans, generates residues like husk, pulp, and silverskin, which have been considered a promising source of bioactive metabolites. Recovering these metabolites offers a sustainable strategy to obtain natural food additives. Based on the above, this study aimed to determine the effect of the aqueous extract obtained from maceration and fungal fermented coffee silverskin (CSS) on ground pork meat’s oxidative and microbiological stability. Treatments used to recover bioactive compounds from CSS were the following: maceration extraction (ME) using 0, 1.5, and 3.0% of CSS (ME–0%, ME–1.5%, and ME–3%); fungal submerged fermentation extraction (FE) using 0, 1.5, and 3.0% of CSS (FE–0%, FE–1.5%, and FE–3%) and Pleurotus pulmonarius mycelium. Concerning metabolite content and bioactivity, results showed a decrease in the carbohydrate content of the ME and FE-obtained, as well as an increase in the phenol, flavonoid, and caffeoylquinic acid content. Also, an increase in radical cation scavenging activity, reducing power values and antibacterial activity of the extracts obtained with FE, was observed. Regarding pork meat homogenate treated with ME and FE extracts and subjected to oxidation with potassium ferrocyanide, results demonstrated that inclusion of FE-obtained extract led to decreased pH, lipid oxidation, metmyoglobin, and color changes (L*, a*, b*, C*, and h*), and microbial growth. These results demonstrate that CSS aqueous extract obtained with FE can be considered a potential additive for the meat industry with antioxidant and antibacterial activity. Nevertheless, further research is necessary to assess the sensory impact, biochemical mechanism, food safety, sustainability, and industrial feasibility of these extracts for broader applications. Full article

Based on coffee’s unique and fascinating flavor, coffee has become the most popular nonalcoholic drink in the world and is a significant agricultural economic crop in tropical- and subtropical-planted coffee countries and regions. It is also beneficial for human health because of its rich active compounds, such as caffeine, chlorogenic acids, trigonelline, tryptophan alkaloids, diterpenes, melanoidins, etc. These compounds often relate to the prevention of cardiovascular disease, Alzheimer’s disease, and antibacterial, anti-diabetic, neuroprotection, and anti-cancer activities. The formation of coffee’s flavor results from various influence factors, including genetics, shade, elevation, post-harvest processing, fermentation, roasted methods, etc. The first stage of coffee production is obtaining green coffee beans through the primary process. Fermentation is critical in the primary process of coffee, which is often related to yeasts, bacteria, and filamentous fungi. Therefore, microorganisms play a key role in coffee fermentation and coffee flavor. To provide an understanding of the role of microorganisms in coffee fermentation, the coffee fermentation overview and microbial characteristics in different coffee primary processing methods and different coffee fermentation regions were reviewed in this paper. Brazil and China are the main study countries in coffee fermentation, which contribute a large number of technologies and methods to improve coffee flavor by fermentation. Different primary processing methods (wet, dry, or semi-dry processing) and coffee producer countries had obvious microbial community characteristics. Moreover, the application of yeast and bacteria for improving coffee flavor by microbial fermentation was also introduced. Full article

Utilizing coffee by-products in the fermentation process of coffee offers a sustainable strategy by repurposing agricultural waste and enhancing product quality. This study evaluates the effect of applying a starter culture, derived from coffee residues, on the dynamics of reducing and total sugars during coffee fermentation, as well as the composition of aromatic compounds, organic acids, and the sensory profile of coffee inoculated with yeast (Saccharomyces cerevisiae) and lactic acid bacteria (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus), in comparison to a spontaneously fermented sample. Volatile compounds were identified and quantified using dynamic headspace gas chromatography-mass spectrometry (HS/GC-MS), with predominant detection of 2-furancarboxaldehyde, 5-methyl; 2-furanmethanol; and furfural—compounds associated with caramel, nut, and sweet aromas from the roasting process. A reduction in sugars (glucose, fructose, and sucrose) occurred over the 36 h fermentation period. Lactic acid (2.79 g/L) was the predominant organic acid, followed by acetic acid (0.69 g/L). The application of the inoculum improved the sensory quality of the coffee, achieving a score of 86.6 in evaluations by Q-graders, compared to 84 for the control sample. Additionally, descriptors such as red apple, honey, and citrus were prominent, contributing to a uniform and balanced flavor profile. These findings indicate that controlled fermentation with starter cultures derived from coffee by-products enhances sustainability in coffee production. It achieves this by supporting a circular economy, reducing reliance on chemical additives, and improving product quality. This approach aligns with sustainable development goals by promoting environmental stewardship, economic viability, and social well-being within the coffee industry. Full article

The washed process is one of the traditional post-harvest processes of coffee beans, which include selective harvesting, flotation, pulping, submerged fermentation underwater, washing, and drying operations. During the washed processing, fermentation underwater can remove coffee mucilage and change metabolites by microorganisms. Therefore, coffee fermentation is a key factor influencing coffee’s flavor. To compare the influence of fermentation duration in an open environment of Coffea arabica in 48 h during the washed processing on the coffee’s flavor, the sensory characteristics of the coffee at different fermentation durations were evaluated using the Specialty Coffee Association of America (SCAA) cupping protocol. Moreover, ultra performance liquid chromatography–triple quadrupole mass spectrometry (UHPLC–MS/MS) and gas chromatography–mass spectrometry (GC–MS) were combined to analyze and compare the chemical compounds of coffee samples from fermentation durations of 24 h (W24) and 36 h (W36) during the washed processing method. The results showed that W36 had the highest total cupping score with 77.25 in all different fermentation duration coffee samples, and 2567 non-volatile compounds (nVCs) and 176 volatile compounds (VCs) were detected in W36 and W24 during the washed processing method. Furthermore, 43 differentially changed non-volatile compounds (DCnVCs) and 22 differentially changed volatile compounds (DCVCs) were detected in W36 vs. W24. Therefore, suitable fermentation duration in an open environment is beneficial to coffee flavor, judging by chemical compound changes. For the washed primary processing of C. arabica from Yunnan, China, 36 h fermentation was the suitable fermentation duration in an open environment, which presented potential value as the reference for washed coffee processing in the food industry. Full article