Characterization of Fatty Acid, Amino Acid and Volatile Compound Compositions and Bioactive Components of Seven Coffee (Coffea robusta) Cultivars Grown in Hainan Province, China

Literature Review of Proteomics Approach Associated with Coffee

As a significant crop growing all across the world, coffee is mostly produced in the bean belt of our global atlas. Worldwide variations in environmental conditions are causing a decline in the yield and quality of coffee varieties. Coffee production is the main emphasis of several traditional breeding techniques. But conventional breeding methods are not sufficient to tackle the problems related to coffee. The field of genomics, which includes transcriptomics, proteomics, and metabolomics, has made great paces in the last ten years. Proteomics is a well-known technique used to enhance the growth, yield, breeding, and quality of different plants under stable and shifting environments. The regulation of specific enzymes, genes, protein expression, modification, translation, and other features played an important role in the enhancement of important plants. However, relatively less research on the proteomics approach for coffee has been published in the last few years. For this reason, some of the most important aspects of proteome profiling for coffee plants have been covered in this review, including growth, the somatic embryo technique, altitude, environmental adoption, drought, and the role that proteins and important enzymes play in the flavor and taste of coffee. This review can aid in the breeding of new cultivars and improve coffee attributes. Furthermore, the present literature can pave the way for proteomics research on coffee.

Exploring the microbiome of coffee plants: Implications for coffee quality and production

Coffee stands as one of the world's most popular beverages, and its quality undergoes the influence of numerous pre- and post-harvest procedures. These encompass genetic variety, cultivation environment, management practices, harvesting methods, and post-harvest processing. Notably, microbial communities active during fermentation hold substantial sway over the ultimate quality and sensory characteristics of the final product. The interaction between plants and microorganisms assumes critical significance, with specific microbes assuming pivotal roles in coffee plant growth, fruit development, and, subsequently, the fruit's quality. Microbial activities can synthesize or degrade compounds that influence the sensory profile of the beverage. However, studies on the metabolic products generated by various coffee-related microorganisms and their chemical functionality, especially in building sensory profiles, remain scarce. The primary aim of this study was to conduct a literature review, based on a narrative methodology, on the current understanding of the plant-microorganism interaction in coffee production. Additionally, it aimed to explore the impacts of microorganisms on plant growth, fruit production, and the fermentation processes, directly influencing the ultimate quality of the coffee beverage. Articles were sourced from ScienceDirect, Scopus, Web of Science, and Google Scholar using specific search terms such as "coffee microorganisms", "microorganisms-coffee interactions", "coffee fermentation", "coffee quality", and 'coffee post-harvest processing". The articles used were published in English between 2000 and 2023. Selection criteria involved thoroughly examining articles to ensure their inclusion was based on results about the contribution of microorganisms to both the production and quality of the coffee beverage. The exploration of microorganisms associated with the coffee plant and its fruit presents opportunities for bioprospecting, potentially leading to targeted fermentations via starter cultures, consequently generating new profiles. This study synthesizes existing data on the current understanding of the coffee-associated microbiome, its functionalities within ecosystems, the metabolic products generated by microorganisms, and their impacts on fermentation processes and grain and beverage quality. It highlights the importance of plant-microorganism interactions in the coffee production chain.

Inverted U-shaped relationship between coffee consumption and serum uric acid in American chronic kidney disease population

Objective

The objective of this study was to examine the contentious relationship between coffee consumption and serum uric acid (SUA) levels, specifically within American population with chronic kidney disease (CKD).

Methods

A total of 23,381 participants from the 2001-2018 National Health and Nutrition Examination Survey (NHANES) were selected for inclusion in this investigation. Linear regression models and generalized additive models with smooth curve fitting were employed to analyze the association between log coffee consumption and serum uric acid levels. Furthermore, the robustness of the findings was assessed across diverse populations.

Results

The results of the linear regression analysis indicate a positive and marginally statistically significant (p = 0.0307) association between log coffee consumption and SUA, even after controlling for other variables. Furthermore, the generalized additive model revealed a nonlinear relationship characterized by an inverted U-shape between log coffee consumption and SUA. The inflection point, identified as 11.43 g/day, marks the point at which this relationship changes direction. Moreover, this inverted U-shaped relationship was consistently observed across various subgroups, including gender, age (<60 and ≥ 60 years), hypertensive and non-hypertensive individuals, those with and without cardiovascular disease, non-diabetic individuals, and those who consumed coffee with or without caffeine or sugar.

Conclusion

An inverse U-shaped correlation has been observed between log coffee consumption and SUA levels. This finding implies that once coffee consumption surpasses a specific threshold, it promotes a decline in SUA levels.

Development of rapid and non-destructive electric nose (E-nose) system for shelf life evaluation of different edible seeds

Shelf life estimation is crucial in ensuring the quality of food products. However, traditional methods are time-consuming and inefficient. Therefore, there is an urgent need for simple, efficient and rapid techniques for quality assessments. An electronic nose (E-nose) serves as a solution by rapidly and accurately detecting release of volatile organic compounds (VOCs) during food deterioration. This study aims to develop Arduino-Uno R3 microprocessor based E-nose, equipped with MQ4, MQ5, MQ9 and MQ135 sensors for evaluating shelf life of different edible seeds over the storage period of 150 days. Sensor values were recorded, revealing a significant increase (p-value ≤ 0.05) in MQ5 sensor readings for Nigella seeds from 349 to 480. Sensor values were positively correlated with physical, microbiological and Fourier-transform infrared (FTIR) spectroscopy parameters. Maximum peak shifts were observed from 3000 cm^-1 to 2800 cm^-1 and 1500 cm^-1 to 1000 cm^-1 wavenumbers. Hence, this study provides successful E-nose system to determine shelf life of seeds.

Effect of different drying airflows and harvest periods on the quality of specialty coffee (Coffea arabica L.)

Coffee is one of the most consumed commercial beverages worldwide, and coffee growers are constantly seeking innovative processing techniques to improve the quality of the final product. This study evaluated the influence of four drying airflows and three harvest periods on the chemical composition of green and roasted specialty coffee beans. The samples were obtained from the Hacienda La Papaya in Loja, Ecuador. Liquid and gas chromatographic techniques characterized the chemical profile of coffee beans, and sensory analysis was performed using the Specialty Coffee Association of America methodology. In total, 49 compounds were described, 29 in green beans and 20 in roasted beans. A significant (p<0.05) effect of the harvest period was observed in all phenolic compounds except for chlorogenic acid. The drying type significantly affected the levels of rutin and trigonelline. In addition, samples from different harvest periods observed significant differences in the levels of the amino acids serine, arginine, phenylalanine and leucine. Similarly, the drying type significantly influenced glycine, alanine, valine and isoleucine levels. For all drying-harvest combinations, the final cupping score was higher than 85/100, as the different drying processes slightly influenced the cupping attributes. Drying with minimal airflow was characterized by a low balance and intense flavor while drying with medium airflow presented a high ratio and soft body. The harvest period and drying type cannot be used as cupping predictors since no clear trends were observed to classify specialty coffee organoleptic attributes. Therefore, other variables involved in specialty coffee processing should be explored to evaluate higher sensitivity toward flavor prediction and innovation. Keywords: chromatographic analysis, Coffea arabica L., sensory analysis, specialty coffee.

Potential therapeutic benefits of unconventional oils: assessment of the potential in vitro biological properties of some Rubiaceae, Cucurbitaceae, and Brassicaceae seed oils

Introduction

Seed oils are versatile in the food sector and for pharmaceutical purposes. In recent years, their biological properties aroused the interest of the scientific world.

Materials and methods

We studied the composition of fatty acids (FAs) and some in vitro potential therapeutic benefits of five cold-pressed commercial oils obtained from broccoli, coffee, green coffee, pumpkin, and watermelon seeds. In particular, we assayed the antioxidant activity (using diphenyl-1-picrylhydrazyl (DPPH) and azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays). In addition, through the fatty acid composition, we calculated the atherogenicity index (AI) and thrombogenicity index (TI) to evaluate the potential impact of such oils on cardiovascular diseases. Furthermore, we assessed the in vitro anti-inflammatory capacity of the oils (evaluated through their effectiveness in preventing protein degradation, using bovine serum albumin as protein standard) and the ability of the oils to inhibit in vitro activity of three among the essential enzymes, cholinesterases and tyrosinase, involved in the Alzheimer's and Parkinson's neurodegenerative diseases. Finally, we evaluated the capacity of the oils to inhibit the biofilm of some pathogenic bacteria.

Results

The unsaturated fatty acids greatly predominated in broccoli seed oil (84.3%), with erucic acid as the main constituent (33.1%). Other unsaturated fatty acids were linolenic (20.6%) and linoleic (16.1%) acids. The saturated fatty acids fraction comprised the palmitic (6.8%) and stearic acids (0.2%). Broccoli seed oil showed the best AI (0.080) and TI (0.16) indexes. The oils expressed a good antioxidant ability. Except for the watermelon seed oil, the oils exhibited a generally good in vitro anti-inflammatory activity, with IC₅₀ values not exceeding 8.73 micrograms. Broccoli seed oil and green coffee seed oil showed the best acetylcholinesterase inhibitory activity; coffee seed oil and broccoli seed oil were the most effective in inhibiting butyrylcholinesterase (IC₅₀ = 15.7 μg and 20.7 μg, respectively). Pumpkin and green coffee seed oil showed the best inhibitory activity against tyrosinase (IC₅₀ = 2 μg and 2.77 μg, respectively). In several cases, the seed oils inhibited the biofilm formation and the mature biofilm of some gram-positive and gram-negative bacteria, with Staphylococcus aureus resulting in the most sensitive strain. Such activity seemed related only in some cases to the capacity of the oils to act on the sessile bacterial cells' metabolism, as indicated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric method.

Supercritical Carbon Dioxide in Presence of Water for the Valorization of Spent Coffee Grounds: Optimization by Response Surface Methodology and Investigation of Caffeine Extraction Mechanism

Spent coffee grounds are a promising bioresource that naturally contain around 50 wt% moisture which requires, for a valorization, a drying step of high energy and economic costs. However, the natural water in spent coffee grounds could bring new benefits as a co-solvent during the supercritical CO₂ extraction (SC-CO₂). This work reports the influence and optimization of pressure (115.9-284.1 bars), temperature (33.2-66.8 °C), and moisture content (6.4-73.6 wt%) on simultaneous extraction of lipids and polar molecules contained in spent coffee grounds by supercritical CO₂ (SC-CO₂) using Central Composite Rotatable Design and Response Surface Methodology. The results show that for lipids extraction, pressure is the most influent parameter, although the influence of moisture content is statistically negligible. This suggests that water does not act as barrier to CO₂ diffusion in the studied area. However, moisture content is the most influent parameter for polar molecules extraction, composed of 99 wt% of caffeine. Mechanism investigations highlight that H₂O mainly act by (i) breaking caffeine interactions with chlorogenic acids present in spent coffee grounds matrix and (ii) transferring selectively caffeine without chlorogenic acid by liquid/liquid extraction with SC-CO₂. Thus, the experiment for the optimization of lipids and polar molecules extraction is performed at a pressure of 265 bars, a temperature of 55 °C, and a moisture content of 55 wt%.

Characteristic Volatile Organic Compound Analysis of Different Cistanches Based on HS-GC-IMS

Cistanche is a medicinal and food homologous substance with a long history of consumption and medicinal use in China. In order to further understand the volatile organic compound differences between different cistanches, this study selected oil cistanche, blood cistanche and cistanche tubulosa in Xinjiang for HS-GC-IMS volatile organic compounds, and established the characteristic fingerprints of different cistanches for organic content and characteristic organic compound analysis. PCA and cluster analysis were used to study the similarity between different cistanches. After qualitative analysis, a total of 32 volatile organic compounds were identified, covering aldehydes (17), ketones (5), furans (1), alcohols (5), lactones (1) and esters (3), and the volatile organic compounds between samples a, b and c could be significantly distinguished, affecting the flavor of cistanche itself. It provides a basic theoretical basis for the study of cistanche flavor.

A Green Analytical Method Combined with Chemometrics for Traceability of Tomato Sauce Based on Colloidal and Volatile Fingerprinting

Tomato sauce is a world famous food product. Despite standards regulating the production of tomato derivatives, the market suffers frpm fraud such as product adulteration, origin mislabelling and counterfeiting. Methods suitable to discriminate the geographical origin of food samples and identify counterfeits are required. Chemometric approaches offer valuable information: data on tomato sauce is usually obtained through chromatography (HPLC and GC) coupled to mass spectrometry, which requires chemical pretreatment and the use of organic solvents. In this paper, a faster, cheaper, and greener analytical procedure has been developed for the analysis of volatile organic compounds (VOCs) and the colloidal fraction via multivariate statistical analysis. Tomato sauce VOCs were analysed by GC coupled to flame ionisation (GC-FID) and to ion mobility spectrometry (GC-IMS). Instead of using HPLC, the colloidal fraction was analysed by asymmetric flow field-fractionation (AF4), which was applied to this kind of sample for the first time. The GC and AF4 data showed promising perspectives in food-quality control: the AF4 method yielded comparable or better results than GC-IMS and offered complementary information. The ability to work in saline conditions with easy pretreatment and no chemical waste is a significant advantage compared to environmentally heavy techniques. The method presented here should therefore be taken into consideration when designing chemometric approaches which encompass a large number of samples.

A Comparative Study for Nutritional and Phytochemical Profiling of Coffea arabica (C. arabica) from Different Origins and Their Antioxidant Potential and Molecular Docking

Coffee is the most widely used beverage globally and contains many bioactive compounds, including phenolic compounds, alkaloids, triterpenes, organic acids, amino acids, hormones, and fatty acids. The main objective of this study was the comparative profiling of Australian, Colombian, Ethiopian, and Peruvian C. arabica using LC-ESI-QTOF-MS/MS. In this study, we tentatively identified 136 bioactive metabolites, including five (05) organic acids, six (06) alkaloids, three (03) amino acids (l-phenylalanine, l-tyrosine, and l-pyroglutamic acid), two (02) hormones (melatonin and serotonin), two fatty acids, one (01) furopyrans (goniothalenol), one (01) carotenoid (crocetin), three (03) terpenoids, thirty-eight (38) phenolic acids, forty-one (41) flavonoids, five (05) stilbenes, three (03) lignans and twenty-three (23) other polyphenols in C. arabica. The highest TPC value (17.74 ± 0.32 mg GAE/g) was measured in Colombian coffee while the lowest TPC value (10.24 ± 0.73 mg GAE/g) was in Peruvian coffee. Colombian coffee has a higher antioxidant potential than other studied coffee samples. A total of nineteen phenolic metabolites were mapped through LC-MS/MS. Quinic acid derivatives were quantified in higher concentrations than other metabolites. Furthermore, molecular docking predicted that chlorogenic acid is a main bioactive compound that contributes to anti-Alzheimer and anti-diabetic activities of C. arabica. The obtained results indicate that C. arabica contains a vast number of bioactive compounds which have potential health benefits. Furthermore, research could be conducted to validate the effect of these metabolites on the flavor profile of coffee beverages.

Comprehensive analysis of quality characteristics in main commercial coffee varieties and wild Arabica in Kenya

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The contents of key non-volatile compounds, including chlorogenic acid, trigonelline, caffeine, and sucrose, vary significantly among Arabica cultivars in Kenya.

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Trigonelline is strongly associated with quality attributes of coffee brews.

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Pyrazines and thiols are major coffee flavor determinants in commercial cultivars in Kenya.

Coffee flavor is a complex commercial trait and its generation mechanisms remain largely unclear. Here, we investigated non-volatile and volatile compounds in the AA grade coffee beans of cultivated and wild Coffea arabica accessions in Kenya. An increased accumulation of trigonelline and sucrose along with a decreased accumulation of caffeine and 5-caffeoylquinic acid or chlorogenic acid (CGA) relative to wild Arabica contribute to the improved flavor of commercial varieties. Trigonelline was strongly associated with attributes of coffee brews such as pH, aroma intensity and antioxidant activity, suggesting that it is one of the main flavor precursors. Partial least squares discriminant analysis (PLS-DA) identified 18 volatiles that could potentially define flavor quality of coffee brews, with pyrazines and thiols as the major coffee flavor determinants.

Comparative Analysis of Selected Chemical Parameters of Coffea arabica, from Cascara to Silverskin

Nowadays, there is an increased interest in coffee derivatives (green beans, roasted beans, and coffee by-products (Cascara and Silverskin)) due to their particular chemical composition. This study aimed to compare the content of dry matter, total fat, fatty acids, and fiber (ADF, NDF) of coffee by-products (Cascara and Silverskin) and coffee beans (green and roasted under different conditions). Coffee beans and their by-products were obtained from 100% C. arabica coffee cherries from Panama by dry process. The lowest concentrations of fat corresponded to Cascara 4.24 g·kg⁻¹ and Silverskin 23.70 g·kg⁻¹, respectively. The major fatty acids detected in all samples were palmitic, stearic, oleic, and linoleic acids, the latter two being essential fatty acids. LDA showed that 89.01% of the variability between beans and by-products was explained by lignoceric, myristic, behenic, tricosanoic, arachidic, and heneicosanoic acids. Silverskin appeared to be a good source of lignoceric, myristic, and behenic acids and had a higher concentration of dietary fiber (314.95 g·kg⁻¹) than Cascara (160.03 g·kg⁻¹). Coffee by-products (Silverskin and Cascara) are low-fat products enriched in dietary fiber. Their incorporation, after adjustment, into the global diet may contribute to nutrition security, the sustainability of the coffee sector, and human health.

Review on factors affecting coffee volatiles: from seed to cup

The objective of this review is to evaluate the influence of six factors on coffee volatiles. At present, the poor aroma from robusta or low-quality arabica coffee can be significantly improved by advanced technology, and this subject will continue to be further studied. On the other hand, inoculating various starter cultures in green coffee beans has become a popular research direction for promoting coffee aroma and flavor. Several surveys have indicated that shade and altitude can affect the content of coffee aroma precursors and volatile organic compounds (VOCs), which remain to be fully elucidated. The emergence of the new roasting process has greatly enriched the aroma composition of coffee. Cold-brew coffee is one of the most popular trends in coffee extraction currently, and its influence on coffee aroma is worthy of in-depth and detailed study. Omics technology will be one of the most important means to analyze coffee aroma components and their quality formation mechanism. A better understanding of the effect of each parameter on VOCs would assist coffee researchers and producers in the optimal selection of post-harvest parameters that favor the continuous production of flavorful and top-class coffee beans and beverages. © 2021 Society of Chemical Industry.

Volatile Flavor Profile and Sensory Properties of Vegetable Soybean

The volatile flavor profiles and sensory properties of different vegetable soybean varieties popularized and cultivated in China for 20, 10, and 2 years (TW292, X3, and SX6, respectively) were investigated. Nutrient composition analysis revealed that TW292 had a high soluble protein and soluble sugar content but low fat content. The total free amino acid content (15.43 mg/g) and umami free amino acid content (6.08 mg/g) of SX6 were significantly higher (p < 0.05) than those of the other varieties. An electronic tongue effectively differentiated between the umami and sweetness characteristics of the vegetable soybeans. Differences in sensory evaluation results were mainly reflected in texture and taste. A total of 41 volatile compounds were identified through HS-SPME-GC-MS, and the main flavor compounds were 1-octen-3-ol, hexanal, (Z)-2-heptenal, 2-octene, nonanal, (Z)-2-decenal, and 3,5-octadien-2-one. However, the volatile composition of different vegetable soybean varieties exhibited large variability in type and relative contents. Considerable differences in nutritional, organoleptic, and aroma characteristics were found among different varieties. The results of this study will provide a good basis for the assessment and application of the major vegetable soybean varieties grown in China.

Comparative flavor analysis of four kinds of sweet fermented grains by sensory analysis combined with GC-MS

Four types of cereals (glutinous rice, purple rice, red rice, yellow millet) were selected to produce sweet fermented grains. Flavor profiles of sweet fermented grains are comparatively studied to distinguish various flavor types by using GC-MS, electronic nose (E-nose), and sensory analysis, and the amino acid composition and physicochemical properties of sweet fermented grains were analyzed. The results showed that the volatile compounds of sweet fermented grains were significantly different. Esters and alcohols were the major volatile compounds in sweet fermented grains. The electronic nose, electronic tongue and sensory analysis jointly verified that the volatile components of sweet fermented grains had differences between them. The sweet fermented grains could be classified based on differences in volatile compounds. In the amino acids analysis, Glu, Pro, Asp and Leu were the most abundant. The difference in physicochemical properties is more helpful to distinguish different types of sweet fermented grains. Correlation analysis between antioxidant active substances and color value showed a positive correlation between with a* value, and a negative correlation with L*, b* value. Our results suggested that there were differences in the flavor characteristics of sweet fermented grains fermented from different types of cereals. The results of the study will provide valuable information for the selection of raw materials for sweet fermented grains.

Development of an Online Detection Setup for Dissolved Gas in Transformer Insulating Oil

The type and concentration of dissolved gases in transformer insulating oil are used to assess transformer conditions. In this paper, an online detection setup for measuring the concentration of multicomponent gases dissolved in transformer insulating oil is developed, which consists of an oil-gas separation system and an optical system for acquiring the transformer status in real time. The oil-gas separation system uses low pressure, constant temperature, and low-frequency stirring as working conditions for degassing large-volume oil samples based on modified headspace degassing. The optical system uses tunable diode laser absorption spectroscopy (TDLAS) to determine the gas concentration. Six target gases (methane, ethylene, ethane, acetylene, carbon monoxide, and carbon dioxide) were detected by three near-infrared lasers (1569, 1684, and 1532 nm). The stability of the optical system was improved by the common optical path formed by time-division multiplexing (TDM) technology. The calibration experiments show that the second harmonics and the concentrations of the six gases are linear. A comparison experiment with gas chromatography (GC) demonstrates that the error of acetylene reaches the nL/L level, while the other gases reach the μL/L level. The data conforms to the power industry testing standards, and the state of the transformer is analyzed by the detected six characteristic gases. The setup provides an effective basis for the online detection of dissolved gas in transformer insulating oil.

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.

Climate Change and Coffee Quality: Systematic Review on the Effects of Environmental and Management Variation on Secondary Metabolites and Sensory Attributes of Coffea arabica and Coffea canephora

Climate change is impacting crop performance and agricultural systems around the world with implications for farmers and consumers. We carried out a systematic review to synthesize evidence regarding the effects of environmental factors associated with climate change and management conditions associated with climate adaptation on the crop quality of a culturally-relevant perennial crop, coffee (Coffea arabica and Coffea canephora). Seventy-three articles were identified that addressed the study's research question including 42 articles on environmental factors, 20 articles on management conditions, and 11 articles on both. While variation was found between studies, findings highlight that coffee quality is vulnerable to changes in light exposure, altitude, water stress, temperature, carbon dioxide, and nutrient management. Both increases as well as decreases were found in secondary metabolites and sensory attributes that determine coffee quality in response to shifts in environmental and management conditions. The most consistent evidence identified through this systematic review includes the following two trends: (1) increased altitude is associated with improved sensory attributes of coffee and; (2) increased light exposure is associated with decreased sensory attributes of coffee. Research gaps were found regarding the effects of shifts in carbon dioxide, water stress, and temperature on the directionality (increase, decrease, or non-linear) of coffee quality and how this varies with location, elevation, and management conditions. This systematic review further identified the following research needs: (1) long-term studies that examine the interactive effects of multiple environmental factors and management conditions on coffee quality; (2) studies that examine the interaction between sensory attributes and secondary metabolites that determine coffee quality and; (3) studies on the feasibility of various climate-adaptation strategies for mitigating the effects of climate change on coffee quality. Evidence-based innovations are needed to mitigate climate impacts on coffee quality toward enhanced sustainability and resilience of the coffee sector from farm to cup.

Green coffee: economic relevance and a systematic review of the effects on human health

Coffee is probably the most popular beverage after water and is an important component in diet and health since its consumption is high worldwide. Globally, it is the most relevant food commodity being just behind crude oil. Besides its pleasant flavor, it is an antioxidant source due to polyphenols, which are protective compounds against several diseases. This study aimed to evaluate the economic relevance and perform a systematic review of green coffee's effects on human health. Databases such as MEDLINE-PubMed, EMBASE, COCHRANE, and GOOGLE SCHOLAR were searched, and PRISMA guidelines were followed. Green coffee is considered a novel food product because consumers usually consume only roasted coffee. It can be marketed as such or as an extract. Due to the content of bioactive compounds, which are partially lost during the roasting process, the extracts are usually marketed concerning the potential regarding health effects. Green coffee can be used as dietary supplements, cosmetics, and pharmaceuticals, as a source of antioxidants. It can benefit human health, such as improvement in blood pressure, plasma lipids, and body weight (thus contributing to the improvement of risk components of Metabolic Syndrome). Moreover, benefits for cognitive functions may also be included.

Sniff Species: SURMOF-Based Sensor Array Discriminates Aromatic Plants beyond the Genus Level

Lamiaceae belong to the species-richest family of flowering plants and harbor many species that are used as herbs or in medicinal applications such as basils or mints. The evolution of this group has been driven by chemical speciation, mainly volatile organic compounds (VOCs). The commercial use of these plants is characterized by adulteration and surrogation to a large extent. Authenticating and discerning this species is thus relevant for consumer safety but usually requires cumbersome analytics, such as gas chromatography, often coupled with mass spectroscopy. Here, we demonstrate that quartz-crystal microbalance (QCM)-based electronic noses provide a very cost-efficient alternative, allowing for fast, automated discrimination of scents emitted from the leaves of different plants. To explore the range of this strategy, we used leaf material from four genera of Lamiaceae along with lemongrass, which is similarly scented but from an unrelated outgroup. To differentiate the scents from different plants unambiguously, the output of the six different SURMOF/QCM sensors was analyzed using machine learning (ML) methods together with a thorough statistical analysis. The exposure and purging of data sets (four cycles) obtained from a QCM-based, low-cost homemade portable e-Nose were analyzed using a linear discriminant analysis (LDA) classification model. Prediction accuracy with repeated test measurements reached values of up to 0%. We show that it is possible not only to discern and identify plants at the genus level but also to discriminate closely related sister clades within a genus (basil), demonstrating that an e-Nose is a powerful device that can safeguard consumer safety against dangers posed by globalized trade.

The level variation of Nε-(carboxymethyl)lysine is correlated with chlorogenic acids in Arabica L. Coffee beans under different process conditions

N^ε-(carboxymethyl) lysine (CML) is universally used as a marker of the occurrence of advanced glycation end products (AGEs) in foods. This study investigated the level changes of CML, chlorogenic acids (CQAs), lysine (Lys), fat and pH in coffee during roasting. The CML level went up slowly in the first 10 mins, then declined sharply during the next 2 mins, and kept increasing constantly in the following baking time, while the lowest CML level was obtained by roasting at 235 °C for 12 mins. The three CQAs isomers had different efficacy in affecting the levels of CML and other factors, indicating the CQAs isomers may play an important role in influencing the CML level. So it might be possible to regulate the formation of CML and gain better coffee quality via adjusting the levels of CQAs in baking process. This study provided important enlightenment on CML control during coffee baking.

Comparison of Batch and Continuous Wet-Processing of Coffee: Changes in the Main Compounds in Beans, By-Products and Wastewater

Many technical challenges still need to be overcome to improve the quality of the green coffee beans. In this work, the wet Arabica coffee processing in batch and continuous modus were investigated. Coffee beans samples as well as by-products and wastewaters collected at different production steps were analyzed in terms of their content in total phenols, antioxidant capacity, caffeine content, organic acids, reducing sugars, free amino group and protein content. The results showed that 40% of caffeine was removed with pulp. Green coffee beans showed highest concentration of organic acids and sucrose (4.96 ± 0.25 and 5.07 ± 0.39 g/100 g DW for the batch and continuous processing). Batch green coffee beans contained higher amount of phenols. 5-caffeoylquinic Acid (5-CQA) was the main constituent (67.1 and 66.0% for the batch and continuous processing, respectively). Protein content was 15 and 13% in the green coffee bean in batch and continuous processing, respectively. A decrease of 50 to 64% for free amino groups during processing was observed resulting in final amounts of 0.8 to 1.4% in the processed beans. Finally, the batch processing still revealed by-products and wastewater with high nutrient content encouraging a better concept for valorization.

Coffee Flavor: A Review

Flavor continues to be a driving force for coffee’s continued growth in the beverage market today. Studies have identified the sensory aspects and volatile and non-volatile compounds that characterize the flavor of different coffees. This review discusses aspects that influence coffee drinking and aspects such as environment, processing, and preparation that influence flavor. This summary of research studies employed sensory analysis (either descriptive and discrimination testing and or consumer testing) and chemical analysis to determine the impact aspects on coffee flavor.

Comparison of the Antioxidant Activities and Volatile Compounds of Coffee Beans Obtained Using Digestive Bio-Processing (Elephant Dung Coffee) and Commonly Known Processing Methods

There are different types of coffee processing methods. The wet (WP) and dry processing (DP) methods are widely practiced in different parts of coffee-growing countries. There is also a digestive bioprocessing method in which the most expensive coffee is produced. The elephant dung coffee is produced using the digestive bioprocessing method. In the present experiment, the antioxidant activity and volatile compounds of coffee that have been processed using different methods were compared. The antioxidant activity, total phenolic content (TPC), total flavonoid content (TFC), and total tannin content (TTC) of green coffee beans from all treatments were higher as compared to roasted coffee beans. Regarding the green coffee beans, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of elephant dung coffee beans was higher as compared to that of the DP and WP coffee beans. The green coffee beans had higher DPPH activity and ferric reducing antioxidant power (FRAP) value compared to the roasted coffee beans. The green beans of elephant dung coffee had a high TPC than the beans obtained by WP and DP methods. TFC in elephant dung coffee in both green and roasted condition was improved in contrast to the beans processed using dry and wet methods. The elephant dung coffee had an increased TTC in comparison to the DP and WP coffee (green beans). About 37 volatile compounds of acids, alcohols, aldehydes, amide, esters, ethers, furans, furanones, ketones, phenols, pyrazines, pyridines, Heterocyclic N, and pyrroles functional classes have been found. Some of the most abundant volatile compounds detected in all treatments of coffee were 2-furanmethanol, acetic acid, 2-methylpyrazine, 2,6-dimethylpyrazine, pyridine, and 5-methylfurfural. Few volatile compounds have been detected only in elephant dung coffee. The principal component analysis (PCAs) was performed using the percentage of relative peak areas of the volatile compound classes and individual volatile compounds. This study will provide a better understanding of the impacts of processing methods on the antioxidants and volatile compounds of coffee.

Detection and Differentiation of Volatile Compound Profiles in Roasted Coffee Arabica Beans from Different Countries Using an Electronic Nose and GC-MS

This paper describes the possibility of electronic nose-based detection and discrimination of volatile compound profiles of coffee from different countries roasted in a Gothot roaster under identical time and thermal regimes. The material used in the study was roasted Arabica coffee beans from Brazil, Ethiopia, Guatemala, Costa Rica, and Peru. The analyses were carried out with the use of the Agrinose electronic nose designed and constructed at the Institute of Agrophysics of the Polish Academy of Sciences in Lublin. The results of the volatile compound profile analysis provided by the Agrinose device were verified with the GC-MS technique. Chemometric tests demonstrated a dominant role of alcohols, acids, aldehydes, azines, and hydrazides in the coffee volatile compound profile. The differences in their content had an impact on the odor profile of the coffees originating from the different countries. High content of pyridine from the group of azines was detected in the coffee from Peru and Brazil despite the same roasting conditions. The results of the Agrinose analysis of volatile substances were consistent and correlated with the GC-MS results. This suggests that the Agrinose is a promising tool for selection of coffees based on their volatile compound profile.

Characterization of the Lipid Oxidation Process of Robusta Green Coffee Beans and Shelf Life Prediction during Accelerated Storage

The lipid oxidation process of Robusta green coffee beans was characterized during accelerated storage for 20 days at 40 °C, 50 °C, and 60 °C. The conventional oxidation indexes and fatty acid compositions were evaluated, and the shelf life of the green coffee beans was predicted using the Arrhenius model. The acid value, iodine value, peroxide value, total oxidation value, thiobarbituric acid reactive substances, and free fatty acid content increased throughout storage, while the moisture content, p-anisidine value, and unsaturated fatty acid content decreased, which suggests that lipid oxidation occurred during accelerated storage. The predicted shelf life of green coffee bean samples were 57.39 days, 44.44 days, and 23.12 days when stored at 40 °C, 50 °C, and 60 °C, respectively. This study provided scientific evidence of the impact of lipid oxidation on the loss of quality during the accelerated storage of green coffee beans.

Gas Chromatography-Mass Spectrometry and Single Nucleotide Polymorphism-Genotype-By-Sequencing Analyses Reveal the Bean Chemical Profiles and Relatedness of Coffea canephora Genotypes in Nigeria

The flavor and health benefits of coffee (Coffea spp.) are derived from the metabolites that accumulate in the mature bean. However, the chemical profiles of many C. canephora genotypes remain unknown, even as the production of these coffee types increases globally. Therefore, we used Gas Chromatography-Mass Spectrophotometry to determine the chemical composition of C. canephora genotypes in Nigeria—those conserved in germplasm repositories and those cultivated by farmers. GC-MS revealed 340 metabolites in the ripe beans, with 66 metabolites differing (p-value < 0.05) across the represented group. Univariate and multivariate approaches showed that the ‘Niaouli’ genotypes could be clearly distinguished from ‘Kouillou’ and ‘Java’ genotypes, while there was almost no distinction between ‘Kouillou’ and ‘Java,’. Varietal genotyping based on bean metabolite profiling was synchronous with that based on genome-wide Single Nucleotide Polymorphism analysis. Across genotypes, the sucrose-to-caffeine ratio was low, a characteristic indicative of low cup quality. The sucrose-to-caffeine ratio was also highly correlated, indicative of common mechanisms regulating the accumulation of these compounds. Nevertheless, this strong correlative link was broken within the ‘Niaouli’ group, as caffeine and sucrose content were highly variable among these genotypes. These ‘Niaouli’ genotypes could therefore serve as useful germplasm for starting a Nigerian C. canephora quality improvement breeding program.

Evaluation of the impact of different drying methods on the phenolic compounds, antioxidant activity, and in vitro digestion of green coffee beans

We investigated the effects of different drying methods (room temperature drying, heat pump drying, freeze drying, microwave vacuum drying [MVD], and combined microwave power vacuum drying) on the active ingredients of green coffee beans. We specifically focused on eleven phenolic acids, total phenolic content (TPC), total flavonoid content, antioxidant activity, polyphenol oxidase (PPO), the inhibition of linoleic acid peroxidation (LPO), and enzyme activity, and the bio-accessibility in vitro and bioavailability of phenolics and antioxidant activities were also evaluated. MVD-treated beans had the lowest PPO activity and the highest contents of 5-caffeoylquinic acid (1.39 g/100 g DW), 3-feruloylquinic acid (0.25 g/100 g DW), 4-feruloylquinic acid (0.25 g/100 g DW), 5-feruloylquinic acid (1.52 g/100 g DW), and TPC (5.98 g GAE/100 g DW), and the highest antioxidant activity. MVD was the least time-consuming (0.63 hr/kg) and energy-consuming (1.88 kwh/kg) method. Moreover, the strongest inhibition of LPO and α-glucosidase was observed in MVD-treated beans. Thus, MVD is suggested to be the most suitable drying technique for the preservation of phenolic compounds and bioactivities of green coffee beans.

The Impact of Coffee and Its Selected Bioactive Compounds on the Development and Progression of Colorectal Cancer In Vivo and In Vitro

Coffee is one of the most popular beverages worldwide. Coffee contains bioactive compounds that affect the human body such as caffeine, caffeic acid, chlorogenic acids, trigonelline, diterpenes, and melanoidins. Some of them have demonstrated potential anticarcinogenic effects in animal models and in human cell cultures, and may play a protective role against colorectal cancer. Colorectal cancer (CRC) is the third leading cause of cancer-related mortality in the USA and other countries. Dietary patterns, as well as the consumption of beverages, may reduce the risk of CRC incidence. In this review, we focus on published epidemiological studies concerning the association of coffee consumption and the risk of development of colorectal cancer, and provide a description of selected biologically active compounds in coffee that have been investigated as potential cancer-combating compounds: Caffeine, caffeic acid (CA), chlorogenic acids (CGAs), and kahweol in relation to colorectal cancer progression in in vitro settings. We review the impact of these substances on proliferation, viability, invasiveness, and metastasis, as well as on susceptibility to chemo- and radiotherapy of colorectal cancer cell lines cultured in vitro.

Effect of Roasting Levels and Drying Process of Coffea canephora on the Quality of Bioactive Compounds and Cytotoxicity

Coffee is a popular drink consumed all over the world. Besides its long-recognized stimulant effect, it has important nutritional and health effects. However, the type of bean processing modifies the composition of brewed coffee and possibly its bioactivity. In this study, extracts obtained from green and roasted beans of Coffea canephora (Coffea canephora var. robusta) were submitted to spray- or freeze-drying and were tested for antiproliferative activity, using MTT assay, and their influence on the cell cycle and apoptosis by flow cytometry analysis. Moreover, colors and nutrient contents were measured to identify the changes due to the roasting process. The results obtained showed that extracts from green and light roasted beans exhibited strong bioactive capacity. Coffee extracts promoted a decrease in cell viability, modulated cell cycle and induced apoptosis in human prostate carcinoma cell line (DU-145). The level of roasting reduced this property, but the type of drying did not in all cases.

Advanced Classification of Coffee Beans with Fatty Acids Profiling to Block Information Loss

Classification is a kernel process in the standardization, grading, and sensory aspects of coffee industries. The chemometric data of fatty acids and crude fat are used to characterize the varieties of coffee. Two category classifiers were used to distinguish the species and roasting degree of coffee beans. However, the fatty acid profiling with normalized data gave a bad discriminant result in the classification study with mixed dimensions in species and roasted degree. The result of the predictive model is in conflict with the context of human cognition, since roasted coffee beans are easily visually distinguished from green coffee beans. By exploring the effects of error analysis and information processing technologies, the lost information was identified as a bias–variance tradeoff derived from the percentile normalization. The roasting degree as extensive information was attenuated by the percentile normalization, but the cultivars as intensive information were enhanced. An informational spiking technique is proposed to patch the dataset and block the information loss. The identified blocking of informational loss could be available for multidimensional classification systems based on the chemometric data.

Coffee, caffeine, chlorogenic acid, and the purinergic system

Coffee is a drink prepared from roasted coffee beans and is lauded for its aroma and flavour. It is the third most popular beverage in the world. This beverage is known by its stimulant effect associated with the presence of methylxanthines. Caffeine, a purine-like molecule (1,3,7 trymetylxantine), is the most important bioactive compound in coffee, among others such as chlorogenic acid (CGA), diterpenes, and trigonelline. CGA is a phenolic acid with biological properties as antioxidant, anti-inflammatory, neuroprotector, hypolipidemic, and hypoglicemic. Purinergic system plays a key role inneuromodulation and homeostasis. Extracellular ATP, other nucleotides and adenosine are signalling molecules that act through their specific receptors, namely purinoceptors, P1 for nucleosides and P2 for nucleotides. They regulate many pathological processes, since adenosine, for instance, can limit the damage caused by ATP in the excitotoxicity from the neuronal cells. The primary purpose of this review is to discuss the effects of coffee, caffeine, and CGA on the purinergic system. This review focuses on the relationship/interplay between coffee, caffeine, CGA, and adenosine, and their effects on ectonucleotidases activities as well as on the modulation of P1 and P2 receptors from central nervous system and also in peripheral tissue.

Exploring the impacts of postharvest processing on the aroma formation of coffee beans - A review

The aim of this review is to describe the volatile aroma compounds of green coffee beans and evaluate sources of variation in the formation and development of coffee aroma through postharvest processing. The findings of this survey showed that the volatile constituents of green coffee beans (e.g., alcohols, aldehydes, and alkanes) have no significant influence on the final coffee aroma composition, as only a few such compounds remain in the beans after roasting. On the other hand, microbial-derived, odor-active compounds produced during removal of the fruit mucilage layer, including esters, higher alcohols, aldehydes, and ketones, can be detected in the final coffee product. Many postharvest processing including drying and storage processes could influence the levels of coffee aroma compositions, which remain to be elucidated. Better understanding of the effect of these processes on coffee aroma composition would assist coffee producers in the optimal selection of postharvest parameters that favor the consistent production of flavorful coffee beans.

Comparative evaluation of the volatile profiles and taste properties of roasted coffee beans as affected by drying method and detected by electronic nose, electronic tongue, and HS-SPME-GC-MS

In this study, room-temperature drying, solar drying, heat pump drying (HPD), hot-air drying, and freeze drying were applied to investigate the volatile profiles and taste properties of roasted coffee beans by using electronic nose, electronic tongue, and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). Results indicated that the drying process markedly affected pH, total titratable acidity, total solids, and total soluble solids. Significant differences existed among all samples based on drying method; and the HPD method was superior for preserving ketones, phenols, and esters. Principal component analysis (PCA) combined with E-nose and E-tongue radar charts as well as the fingerprint of HS-SPME-GC-MS could clearly discriminate samples from different drying methods, with results obtained from hierarchical cluster analysis (the Euclidean distance is 0.75) being in agreement with those of PCA. These findings may provide a theoretical basis for the dehydration of coffee beans and other similar thermo-sensitive agricultural products.

Identification of Volatile Compounds and Selection of Discriminant Markers for Elephant Dung Coffee Using Static Headspace Gas Chromatography-Mass Spectrometry and Chemometrics

Elephant dung coffee (Black Ivory Coffee) is a unique Thai coffee produced from Arabica coffee cherries consumed by Asian elephants and collected from their feces. In this work, elephant dung coffee and controls were analyzed using static headspace gas chromatography hyphenated with mass spectrometry (SHS GC-MS), and chemometric approaches were applied for multivariate analysis and the selection of marker compounds that are characteristic of the coffee. Seventy-eight volatile compounds belonging to 13 chemical classes were tentatively identified, including six alcohols, five aldehydes, one carboxylic acid, three esters, 17 furans, one furanone, 13 ketones, two oxazoles, four phenolic compounds, 14 pyrazines, one pyridine, eight pyrroles and three sulfur-containing compounds. Moreover, four potential discriminant markers of elephant dung coffee, including 3-methyl-1-butanol, 2-methyl-1-butanol, 2-furfurylfuran and 3-penten-2-one were established. The proposed method may be useful for elephant dung coffee authentication and quality control.

The influence of high-temperature heating on composition and thermo-oxidative stability of the oil extracted from Arabica coffee beans

The aim of the present study was to establish the influence of high-temperature heating on the composition and thermal behavior of coffee oils obtained from Arabica green and roasted coffee beans, respectively. Morphological studies performed using scanning electron microscopy revealed the oil bodies uniformly distributed within the cells in both types of coffee beans analyzed. The obtained oils have a fatty acid composition rich in linoleic acid, palmitic acid, oleic acid, stearic acid, arachidic acid and linolenic acid. The total content of saturated fatty acids of investigated oils was 49.38 and 46.55%, the others being unsaturated fatty acids. The thermal behavior and thermo-oxidative stability of coffee oils extracted from green coffee beans and roasted coffee beans, the coffee oil high-temperature heated up to 200 °C, were investigated using simultaneous thermal analysis TG/DTG/DTA, in an oxidizing atmosphere. The data obtained for the analyzed samples depend mainly on the nature and compositions of fatty acids, and to a lesser extent on the roasting process of the coffee beans and the high-temperature heating process of the extracted oil. The chromatographic and TG/DTG/DTA data suggest that Arabica coffee oil has great potential for use in technological processes which require high-temperature heating (e.g. food industry or pastries).

Effect of Microwave Vacuum Drying on the Drying Characteristics, Color, Microstructure, and Antioxidant Activity of Green Coffee Beans

The aim of this study is to investigate the effect of microwave vacuum drying (MVD) on the drying characteristics and quality attributes of green coffee beans. We specifically focused on the effective moisture diffusion coefficient (D_eff), surface temperature, glass transition temperature (T_g), water state, and microstructure. The kinetics of color changes during drying, total phenolic content (TPC), and antioxidant activity (DPPH, FRAP, and ABTS) were also characterized. Microwave power during MVD affected the porosity of coffee beans, their color, TPC, and antioxidant activity. The Allometric 1 model was the most suitable for simulating surface temperature rise kinetics. Thermal processing of green coffee beans resulted in increased b*, L*, ΔE, and TPC values, and greater antioxidant capacity. These findings may provide a theoretical reference for the technical improvement, mechanisms of flavor compound formation, and quality control of dried green coffee beans.

Differentiation of Chinese robusta coffees according to species, using a combined electronic nose and tongue, with the aid of chemometrics

Electronic nose and tongue sensors and chemometric multivariate analysis were applied to characterize and classify 7 Chinese robusta coffee cultivars with different roasting degrees. Analytical data were obtained from 126 samples of roasted coffee beans distributed in the Hainan Province of China. Physicochemical qualities, such as the pH, titratable acidity (TA), total soluble solids (TSS), total solids (TS), and TSS/TA ratio, were determined by wet chemistry methods. Data fusion strategies were investigated to improve the performance of models relative to the performance of a single technique. Clear classification of all the studied coffee samples was achieved by principal component analysis, K-nearest neighbour analysis, partial least squares discriminant analysis, and a back-propagation artificial neural network. Quantitative models were established between the sensor responses and the reference physicochemical qualities, using partial least squares regression (PLSR). The PLSR model with a fusion data set was considered the best model for determining the quality parameters.