16-O-methylcafestol is present in ground roast Arabica coffees: Implications for authenticity testing

Coffee Oil Extraction Methods: A Review

Green and roasted coffee oils are products rich in bioactive compounds, such as linoleic acid and the diterpenes cafestol and kahweol, being a potential ingredient for food and cosmetic industries. An overview of oil extraction techniques most applied for coffee beans and their influence on the oil composition is presented. Both green and roasted coffee oil extractions are highlighted. Pressing, Soxhlet, microwave, and supercritical fluid extraction were the most used techniques used for coffee oil extraction. Conventional Soxhlet is most used on a lab scale, while pressing is most used in industry. Supercritical fluid extraction has also been evaluated mainly due to the environmental approach. One of the highlighted activities in Brazilian agribusiness is the industrialization of oils due to their increasing use in the formulation of cosmetics, pharmaceuticals, and foods. Green coffee oil (raw bean) has desirable bioactive compounds, increasing the interest of private companies and research institutions in its extraction process to preserve the properties contained in the oils.

Impact of coffee and its bioactive compounds on the risks of type 2 diabetes and its complications: A comprehensive review

BACKGROUND

Coffee beans have a long history of use as traditional medicine by various indigenous people. Recent focus has been given to the health benefits of coffee beans and its bioactive compounds. Research on the bioactivities, applications, and effects of processing methods on coffee beans' phytochemical composition and activities has been conducted extensively. The current review attempts to provide an update on the biological effects of coffee on type 2 diabetes (T2D) and its comorbidities.

METHODS

Comprehensive literature search was carried out on peer-reviewed published data on biological activities of coffee on in vitro, in vivo and epidemiological research results published from January 2015 to December 2022, using online databases such as PubMed, Google Scholar and ScienceDirect for our searches.

RESULTS

The main findings were: firstly, coffee may contribute to the prevention of oxidative stress and T2D-related illnesses such as cardiovascular disease, retinopathy, obesity, and metabolic syndrome; secondly, consuming up to 400 mg/day (1-4 cups per day) of coffee is associated with lower risks of T2D; thirdly, caffeine consumed between 0.5 and 4 h before a meal may inhibit acute metabolic rate; and finally, both caffeinated and decaffeinated coffee are associated with reducing the risks of T2D.

CONCLUSION

Available evidence indicates that long-term consumption of coffee is associated with decreased risk of T2D and its complications as well as decreased body weight. This has been attributed to the consumption of coffee with the abundance of bioactive chemicals.

On the Cholesterol Raising Effect of Coffee Diterpenes Cafestol and 16-O-Methylcafestol: Interaction with Farnesoid X Receptor

The diterpene cafestol represents the most potent cholesterol-elevating compound known in the human diet, being responsible for more than 80% of the effect of coffee on serum lipids, with a mechanism still not fully clarified. In the present study, the interaction of cafestol and 16-O-methylcafestol with the stabilized ligand-binding domain (LBD) of the Farnesoid X Receptor was evaluated by fluorescence and circular dichroism. Fluorescence quenching was observed with both cafestol and 16-O-methylcafestol due to an interaction occurring in the close environment of the tryptophan W454 residue of the protein, as confirmed by docking and molecular dynamics. A conformational change of the protein was also observed by circular dichroism, particularly for cafestol. These results provide evidence at the molecular level of the interactions of FXR with the coffee diterpenes, confirming that cafestol can act as an agonist of FXR, causing an enhancement of the cholesterol level in blood serum.

Graphical exploration of 600- and 60-MHz proton NMR spectral datasets from ground roast coffee extracts

This article uses a variety of graphical and mathematical approaches to analyse 600- and 60-MHz ('benchtop') proton NMR spectra acquired from lipophilic and hydrophilic extracts of roasted coffee beans. The collection of 40 authenticated samples comprised various coffee species, cultivars and hybrids. The spectral datasets were analysed by a combination of metabolomics approaches, cross-correlation and whole spectrum methods, assisted by visualisation and mathematical techniques not conventionally employed to treat NMR data. A large amount of information content was shared between the 600-MHz and benchtop datasets, including in its magnitude spectral form, suggesting the potential for a lower cost, lower tech route to conducting informative metabolomics studies.

Identification of New Diterpenoids from the Pulp of Coffea arabica and Their α-Glucosidase Inhibition Activity

Six new (1, 2, 3, 5, 6, and 8) and seven known (4, 7, 9, 10, 11, 12, and 13) diterpenoids have been identified in the pulp of Coffea arabica. The structures of new diterpenoids were elucidated by extensive spectroscopic analysis, including 1D, 2D NMR (HSQC, HMBC, 1H-1H COSY, and ROESY), HRESIMS, IR, DP4+, electronic circular dichroism, and X-ray crystallography analysis. Compound 1 is ent-labdane-type diterpenoid, whereas compounds (2-13) are ent-kaurane diterpenoids. The result of α-glucosidase inhibitory assay demonstrated that compounds (1, 3, 5, 7, and 10) have moderate inhibitory activity with IC50 values of 55.23 ± 0.84, 74.02 ± 0.89, 66.46 ± 1.05, 49.70 ± 1.02, and 76.34 ± 0.46 μM, respectively, compared to the positive control (acarbose, 51.62 ± 0.21 μM). Furthermore, molecular docking analysis has been conducted to investigate the interaction between the compounds and the receptors of α-glucosidase to interpret their mechanism of activity. This study is the first investigation that successfully discovered the presence of diterpenoids within the coffee pulp.

Using 1H low-field NMR relaxometry to detect the amounts of Robusta and Arabica varieties in coffee blends

Low-field nuclear magnetic resonance (LF-NMR) is a method of widespread use in food research due to its non-destructive character and the relatively low cost of the instruments, allowing the determination of oil / fat contents and the achievement of images of different types of food materials, among other uses. In this work, 1H LF-NMR relaxometry was used to distinguish the contributions due to Arabica and Robusta coffee varieties present in coffee blends. As the method detects preferentially the NMR signals due to phases with high molecular mobility, which exhibit longer values of the 1H transverse relaxation time (T2), the difference in the oil contents associated with Arabica and Robusta coffee was the key factor responsible for the detection of the contributions due to each variety. The analysis presented in this work showed that the relative hydrogen index is a useful parameter to be used in quantitative analyses of the contents of each coffee variety present in the blends. The results illustrate the high potential of applicability of LF-NMR relaxometry as a screening tool for quality control and adulteration detection of coffee-related products.

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.

Solid-state NMR spectroscopy of roasted and ground coffee samples: Evidences for phase heterogeneity and prospects of applications in food screening

The advancement in the use of spectroscopic techniques to investigate coffee samples is of high interest especially considering the widespread problems with coffee adulteration and counterfeiting. In this work, the use of solid-state nuclear magnetic resonance (NMR) is investigated as a means to probe the various chemically-distinct phases existent in roasted coffee samples and to detect the occurrence of counterfeiting or adulterations in coffee blends. Routine solid-state ¹H and ¹³C NMR spectra allowed the distinction between different coffee types (Arabica/Robusta) and the evaluation of the presence of these components in coffee blends. On the other hand, the use of more specialized solid-state NMR experiments revealed the existence of phases with different molecular mobilities (e.g., associated with lipids or carbohydrates). The results illustrate the usefulness of solid-state NMR spectroscopy to examine molecular mobilities and interactions and to aid in the quality control of coffee-related products.

Extraction of Diterpene-Phytochemicals in Raw and Roasted Coffee Beans and Beverage Preparations and Their Relationship

Cafestol and kahweol are expressive furane-diterpenoids from the lipid fraction of coffee beans with relevant pharmacological properties for human health. Due to their thermolability, they suffer degradation during roasting, whose products are poorly studied regarding their identity and content in the roasted coffee beans and beverages. This article describes the extraction of these diterpenes, from the raw bean to coffee beverages, identifying them and understanding the kinetics of formation and degradation in roasting (light, medium and dark roasts) as the extraction rate for different beverages of coffee (filtered, Moka, French press, Turkish and boiled). Sixteen compounds were identified as degradation products, ten derived from kahweol and six from cafestol, produced by oxidation and inter and intramolecular elimination reactions, with the roasting degree (relationship between time and temperature) being the main factor for thermodegradation and the way of preparing the beverage responsible for the content of these substances in them.

Authentication of Coffee Blends by 16-O-Methylcafestol Quantification Using NMR Spectroscopy

In 2019, a coffee chain in Taiwan was found to be mixing relatively cheap Robusta beans into products marketed as 100% Arabica. Many studies show 16-OMC is a remarkable marker to distinguish Robusta from Arabica beans, and nuclear magnetic resonance (NMR) is a convenient and efficient technique for 16-OMC quantification. Here, a 500 MHz NMR was employed to determine the content of 16-OMC in coffee for adulterate evaluation. A total of 118 samples were analyzed including products from the coffee chain, raw materials (single coffee beans), and other commercial products. The contents of 16-OMC in single Robusta beans were between 1005.55 and 3208.32 mg/kg and were absent from single Arabica beans. The surveillance results indicate that 17 out of 47 blend products claiming to contain 100% Arabica had 16-OMC quantifications in the range of 155.74–784.60 mg/kg. Furthermore, all 17 products were produced by the same coffee chain. We confirmed that coffee chain adulterated Arabica with Robusta in parts of their products, which claimed to include 100% Arabica. Moreover, this work highlights the free form of 16-OMC was esterified by coffee instantly. The decomposition products of 16-OMC were observed obviously in green Robusta while the mechanisms remain unclear. Future research should focus more on these aspects to further increase our understanding of these mechanisms.

Benchtop (60 MHz) proton NMR spectroscopy for quantification of 16-O-methylcafestol in lipophilic extracts of ground roast coffee

We present a method for analysing the lipophilic fraction extracted from ground coffee beans using 60 MHz proton (¹H) NMR spectroscopy. In addition to the triglycerides from coffee oil, spectral features are seen from a range of secondary metabolites, such as various diterpenes. We demonstrate quantitation of a peak attributed to one such compound, 16-O-methylcafestol (16-OMC), which is of interest as a coffee species marker. It is present in low concentrations (<<50 mg/kg) in Coffea arabica L. ('Arabica') beans, but in orders of magnitude greater concentrations in other coffees, in particular the other commercially grown species C. canephora Pierre ex A. Froehner (commonly known as 'robusta'). A series of coffee extracts spiked with 16-OMC analytical standard are used to establish a calibration, and to estimate 16-OMC concentrations in a range of different coffees (Arabicas and blends with robustas). To validate the method, values obtained are compared with an analogous quantitation method that uses high field (600 MHz) NMR spectroscopy. •Quantitation of 16-O-methylcafestol in ground roast coffee extracts using benchtop (60 MHz) NMR spectroscopy•Validated by comparison with quantitative high field (600 Mz) NMR spectroscopy•Detection limit is sufficient for discovering adulteration of Arabica coffee with non-Arabica species.

The Potential of Spent Coffee Grounds in Functional Food Development

Coffee is a popular and widely consumed beverage worldwide, with epidemiological studies showing reduced risk of cardiovascular disease, cancers and non-alcoholic fatty liver disease. However, few studies have investigated the health effects of the post-brewing coffee product, spent coffee grounds (SCG), from either hot- or cold-brew coffee. SCG from hot-brew coffee improved metabolic parameters in rats with diet-induced metabolic syndrome and improved gut microbiome in these rats and in humans; further, SCG reduced energy consumption in humans. SCG contains similar bioactive compounds as the beverage including caffeine, chlorogenic acids, trigonelline, polyphenols and melanoidins, with established health benefits and safety for human consumption. Further, SCG utilisation could reduce the estimated 6-8 million tonnes of waste each year worldwide from production of coffee as a beverage. In this article, we explore SCG as a major by-product of coffee production and consumption, together with the potential economic impacts of health and non-health applications of SCG. The known bioactive compounds present in hot- and cold-brew coffee and SCG show potential effects in cardiovascular disease, cancer, liver disease and metabolic disorders. Based on these potential health benefits of SCG, it is expected that foods including SCG may moderate chronic human disease while reducing the environmental impact of waste otherwise dumped in landfill.

NMR-Based Approaches in the Study of Foods

In this review, the three different NMR-based approaches usually used to study foodstuffs are described, reporting specific examples. The first approach starts with the food of interest that can be investigated using different complementary NMR methodologies to obtain a comprehensive picture of food composition and structure; another approach starts with the specific problem related to a given food (frauds, safety, traceability, geographical and botanical origin, farming methods, food processing, maturation and ageing, etc.) that can be addressed by choosing the most suitable NMR methodology; finally, it is possible to start from a single NMR methodology, developing a broad range of applications to tackle common food-related challenges and different aspects related to foods.

Targeted and Non-Targeted HPLC Analysis of Coffee-Based Products as Effective Tools for Evaluating the Coffee Authenticity

Coffee is a very popular beverage worldwide. However, its composition and characteristics are affected by a number of factors, such as geographical and botanical origin, harvesting and roasting conditions, and brewing method used. As coffee consumption rises, the demands on its high quality and authenticity naturally grows as well. Unfortunately, at the same time, various tricks of coffee adulteration occur more frequently, with the intention of quick economic profit. Many analytical methods have already been developed to verify the coffee authenticity, in which the high-performance liquid chromatography (HPLC) plays a crucial role, especially thanks to its high selectivity and sensitivity. Thus, this review summarizes the results of targeted and non-targeted HPLC analysis of coffee-based products over the last 10 years as an effective tool for determining coffee composition, which can help to reveal potential forgeries and non-compliance with good manufacturing practice, and subsequently protects consumers from buying overpriced low-quality product. The advantages and drawbacks of the targeted analysis are specified and contrasted with those of the non-targeted HPLC fingerprints, which simply consider the chemical profile of the sample, regardless of the determination of individual compounds present.

Relationship between the Chemical Composition and the Biological Functions of Coffee

Coffee is a Rubiaceae coffee plant ranked as the first of the three most important beverages in the world, with effects including lowering blood sugar, protecting the liver, and protecting the nerves. Coffee contains many chemical components, including alkaloids, phenolic acids, flavonoids, terpenoids, and so on. Chemical components in coffee are the basis of its biological function and taste. The chemical components are the basis of biological activities and form the characteristic aroma of coffee. The main chemical components and biological activities of coffee have been extensively studied, which would provide a relevant basis and theoretical support for the further development of the coffee industry.

Natural Intervarietal Hybrids of Coffea canephora Have a High Content of Diterpenes

The present investigation characterized the diterpene profile of Coffea canephora coffees, which are natural intervarietal hybrids of Conilon and Robusta. The impact of genetic diversity and environment on these compounds was also evaluated. Five genotypes (clones 03, 05, 08, 25, and 66) from six growing sites in the State of Rondônia in the western Amazon (Alto Alegre dos Parecis, São Miguel do Guaporé, Nova Brasilândia do Oeste, Porto Velho, Rolim de Moura, and Alto Paraíso) were analyzed. The contents of kahweol, cafestol, and 16-O-methylcafestol in light-medium roasted coffees were assessed by UPLC. Data were analyzed by ANOVA and Tukey’s test (p ≤ 0.05). The contents of cafestol and 16-O-methylcafestol ranged from 96 to 457 mg 100 g−1 and 75 to 433 mg 100 g−1, respectively. As for kahweol, from absence up to contents of 36.9 mg 100 g−1 was observed. The diterpene profile was dependent on genetics, growing site, and the interaction between these factors. A higher variability was observed for kahweol contents. The natural intervarietal hybrid coffees stood out for their high contents of diterpenes and increased frequency of kahweol presence (77% of the samples).

Recent Applications of Benchtop Nuclear Magnetic Resonance Spectroscopy

Benchtop nuclear magnetic resonance (NMR) spectroscopy uses small permanent magnets to generate magnetic fields and therefore offers the advantages of operational simplicity and reasonable cost, presenting a viable alternative to high-field NMR spectroscopy. In particular, the use of benchtop NMR spectroscopy for rapid in-field analysis, e.g., for quality control or forensic science purposes, has attracted considerable attention. As benchtop NMR spectrometers are sufficiently compact to be operated in a fume hood, they can be efficiently used for real-time reaction and process monitoring. This review introduces the recent applications of benchtop NMR spectroscopy in diverse fields, including food science, pharmaceuticals, process and reaction monitoring, metabolomics, and polymer materials.

Quantitative Monitoring of the Fermentation Process of a Barley Malt Mash by Benchtop 1H NMR Spectroscopy

In order to investigate benchtop NMR spectroscopy as a monitoring tool for fermentation processes, we used a barley malt mash and took various samples over time and analysed them by NMR spectroscopy with 3-(trimethylsilyl)-2,2,3,3-tetradeuteropropionic acid sodium salt (TSP-d4) as an internal standard for the quantification of ethanol and validated the results by two different enzymatic standard test kits for ethanol analysis. We could show that the results between NMR spectroscopy and test kits were consistent with NMR having a much lower standard deviation. Finally, we discussed the applicability of the method as well as the possibility to quantify various other substances.

Low-field benchtop NMR spectroscopy: status and prospects in natural product analysis†

INTRODUCTION

Since a couple of years, low-field (LF) nuclear magnetic resonance (NMR) spectrometers (40-100 MHz) have re-entered the market. They are used for various purposes including analyses of natural products. Similar to high-field instruments (300-1200 MHz), modern LF instruments can measure multiple nuclei and record two-dimensional (2D) NMR spectra.

OBJECTIVE

To review the commercial availability as well as applications, advantages, limitations, and prospects of LF-NMR spectrometers for the purpose of natural products analysis.

METHOD

Commercial LF instruments were compared. A literature search was performed for articles using and discussing modern LF-NMR. Next, the articles relevant to natural products were read and summarised.

RESULTS

Seventy articles were reviewed. Most appeared in 2018 and 2019. Low costs and ease of operation are most often mentioned as reasons for using LF-NMR.

CONCLUSION

As the spectral resolution of LF instruments is limited, they are not used for structure elucidation of new natural products but rather applied for quality control (QC), forensics, food and health research, process control and teaching. Chemometric data handling is valuable. LF-NMR is a rapidly developing niche and new instruments keep being introduced.

Quantitative NMR Methodology for the Authentication of Roasted Coffee and Prediction of Blends

In response to the need from the food industry for new analytical solutions, a fit-for-purpose quantitative ¹H NMR methodology was developed to authenticate pure coffee (100% arabica or robusta) as well as predict the percentage of robusta in blends through the study of 292 roasted coffee samples in triplicate. Methanol was chosen as the extraction solvent, which led to the quantitation of 12 coffee constituents: caffeine, trigonelline, 3- and 5-caffeoylquinic acid, lipids, cafestol, nicotinic acid, N-methylpyridinium, formic acid, acetic acid, kahweol, and 16-O-methylcafestol. To overcome the chemical complexity of the methanolic extract, quantitative analysis was performed using a combination of traditional integration and spectral deconvolution methods. As a result, the proposed methodology provides a systematic methodology and a linear regression model to support the classification of known and unknown roasted coffees and their blends.

Detection of Peanut Adulteration in Food Samples by Nuclear Magnetic Resonance Spectroscopy

The addition of cheap and also readily available raw materials, such as peanut powder, to visually and chemically similar matrices is a common problem in the food industry. When peanuts are used as an adulterant, there is an additional risk of potential health hazard to consumers as a result of allergy-induced anaphylaxis. In this study, different series of peanut admixtures to visually similar food products, such as powdered hazelnuts, almonds, and walnuts, were prepared and analyzed by ¹H nuclear magnetic resonance (NMR) spectroscopy. For identification, an isolated signal at 3.05 ppm in the ¹H NMR spectrum of polar peanut extract was used as an indicator of peanut adulteration. The chemical marker was identified as (2S,4R)-N-methyl-4-hydroxy-l-proline by resynthesis of the compound and used as an internal standard. The signal-to-noise ratio and the integral of the signal of the marker can both be used to detect peanut impurities. Overall, an approximate limit of detection of 4% admixtures of peanut in various food products was determined using a 400 MHz spectrometer. With regard to food fraud, we present a viable screening method for detection of economic-relevant peanut adulteration.

Demystifying NMR spectroscopy: Applications of benchtop spectrometers in the undergraduate teaching laboratory

Undergraduate students can find some aspects of NMR Spectroscopy daunting, and difficult to understand. Due to their flexibility and ease-of-use, 'benchtop' spectrometers can help to clarify key concepts and enhance learning. Here we suggest approaches to demystifying resolution, sensitivity, magnetic field variation and its consequent impact on spectra, quantitation and mixtures.

16-O-Methylated diterpenes in green Coffea arabica: ultra-high-performance liquid chromatography-tandem mass spectrometry method optimization and validation

Coffee diterpenes are the main constituents of the coffee oil unsaponifiable fraction. The three most important diterpenes are cafestol, kahweol, and 16-O-methylcafestol (16-OMC), and they are produced, except for cafestol, only by plants of the Coffea genus. Recently, in addition to these three major diterpenes, another 16-O-methylated diterpene (16-O-methylkahweol: 16-OMK) has been identified and quantified, for the first time, in Robusta coffee. For many years, 16-OMC has been considered present exclusively in Robusta, and so it has been reputed an excellent authenticity marker for the presence of Robusta in coffee products. For its quantification, nuclear magnetic resonance (NMR) has proved very useful when compared with other methods. Quite recently, the detection of very low levels of the two 16-O-methylated diterpenes (16-OMD) 16-OMC and 16-OMK in roasted Arabica was reported. This finding makes the use of NMR methods in 16-OMD quantification in Arabica coffee particularly challenging in view of both the trace amounts of 16-OMD and the impossibility to discriminate between 16-OMC and 16-OMK. The ultra-high performance liquid chromatography mass spectrometry (UHPLC-MS) method, already used to detect 16-OMC and 16-OMK in Arabica roasted coffee, is then more suitable for quantitative analyses. Up to now however, no quantification of coffee 16-OMD via ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) has been carried out; this largely stimulated the present study. For the first time, a simple procedure for the quantitative detection of 16-OMD in Arabica coffee has been developed, and as far as 16-OMC is concerned, fully validated in terms of specificity, linearity, concentration range, limit of detection (LOD), limit of quantification (LOQ), and repeatability following the criteria specified in the EU Commission Decision 2002/675/EC. This method proved to be very specific and sensitive. In order to avoid the chemical complexity generated by the roasting process, the method was optimized and validated on several green Arabica samples from different geographical origins.

Limited genotypic and geographic variability of 16-O-methylated diterpene content in Coffea arabica green beans

The acknowledged marker of Robusta coffee, 16-O-methylcafestol (16-OMC), can be quantified by NMR as a mixture with 16-O-methylkahweol (16-OMK), which accounts for approximately 10% of the mixture. In the present study, we detected and quantified 16-O-methylated diterpenes (16-OMD) in 248 samples of green Coffea arabica beans by NMR. We did not observe any differences between genotypes introgressed by chromosomal fragments of Robusta and non-introgressed genotypes. Environmental effects suggesting a possible protective role of 16-OMD for adaptation, as well as genotypic effects that support a high heritability of this trait were observed. Altogether, our data confirmed the presence of 16-OMD in green Arabica at a level approximately 1.5% that of a typical Robusta, endorsing the validity of 16-OMD as a marker for the presence of Robusta.

New trends in coffee diterpenes research from technological to health aspects

The coffee oil is rich in diterpenes, mainly cafestol and kahweol, which are predominantly present in the esterified form with different fatty acids. Despite their beneficial effects including anti-angiogenic and anti-carcinogenic properties, they have been also associated with negative consequences such as elevation of blood cholesterol. Considering the coffee, it is an important human beverage with biological effects, including potentially health benefits or risks. Therefore, it may have important public health implications due to its widespread massive consumption, with major incidence in the varieties Arabica and Robusta. According to literatures, cafestol (182-1308 mg/100 g), kahweol (0-1265 mg/100 g) and 16-O-methycafestol (0-223 mg/100 g) are the main diterpenes in green and roasted coffee beans. Nevertheless, the coffee species, genetic background, and technological parameters like roasting and brewing have a clear effect on coffee diterpene content. Besides that, bibliographic data indicated that limited studies have specifically addressed the recent analytical techniques used for determination of this class of compounds, being HPLC and GC the most common approaches. For these reasons, this review aimed to actualize the occurrence and the profile of diterpenes in coffee matrices, focusing on the effect of species, roasting and brewing and on the other hand, introduce the current state on knowledge regarding coffee diterpenes determination which are nowadays highly regarded and widely used. In general, since diterpenes exhibit different health effects depending on their consumption dosage, several parameters needs to be carefully analyzed and considered when comparing the results.

Review of Analytical Methods to Detect Adulteration in Coffee

As one of the most consumed beverages in the world, coffee plays many major socioeconomical roles in various regions. Because of the wide coffee varieties available in the marketplaces, and the substantial price gaps between them (e.g., Arabica versus Robusta; speciality versus commodity coffees), coffees are susceptible to intentional or accidental adulteration. Therefore, there is a sustaining interest from the producers and regulatory agents to develop protocols to detect fraudulent practices. In general, strategies to authenticate coffee are based on targeted chemical profile analyses to determine specific markers of adulterants, or nontargeted analyses based on the “fingerprinting” concept. This paper reviews the literature related to chemometric approaches to discriminate coffees based on nuclear magnetic resonance spectroscopy, chromatography, infrared/Raman spectroscopy, and array sensors/indicators. In terms of chemical profiling, the paper focuses on the detection of diterpenes, homostachydrine, phenolic acids, carbohydrates, fatty acids, triacylglycerols, and deoxyribonucleic acid. Finally, the prospects of coffee authentication are discussed.

Interaction of the Coffee Diterpenes Cafestol and 16-O-Methyl-Cafestol Palmitates with Serum Albumins

The main coffee diterpenes cafestol, kahweol, and 16-O-methylcafestol, present in the bean lipid fraction, are mostly esterified with fatty acids. They are believed to induce dyslipidaemia and hypercholesterolemia when taken with certain types of coffee brews. The study of their binding to serum albumins could help explain their interactions with biologically active xenobiotics. We investigated the interactions occurring between cafestol and 16-O-methylcafestol palmitates with Bovine Serum Albumin (BSA), Human Serum Albumin (HSA), and Fatty Free Human Serum Albumin (ffHSA) by means of circular dichroism and fluorimetry. Circular Dichroism (CD) revealed a slight change (up to 3%) in the secondary structure of fatty-free human albumin in the presence of the diterpene esters, suggesting that the aliphatic chain of the palmitate partly occupies one of the fatty acid sites of the protein. A warfarin displacement experiment was performed to identify the binding site, which is probably close but not coincident with Sudlow site I, as the affinity for warfarin is enhanced. Fluorescence quenching titrations revealed a complex behaviour, with Stern–Volmer constants in the order of 10³–10⁴ Lmol⁻¹. A model of the HSA-warfarin-cafestol palmitate complex was obtained by docking, and the most favourable solution was found with the terpene palmitate chain inside the FA4 fatty acid site and the cafestol moiety fronting warfarin at the interface with site I.

The potentiality of NMR-based metabolomics in food science and food authentication assessment

In the last years, there was an increasing interest on nuclear magnetic resonance (NMR) spectroscopy, whose applications experienced an exponential growth in several research fields, particularly in food science. NMR was initially developed as the elective technique for structure elucidation of single molecules and nowadays is playing a dominant role in complex mixtures investigations. In the era of the "omics" techniques, NMR was rapidly enrolled as one of the most powerful methods to approach metabolomics studies. Its use in analytical routines, characterized by rapid and reproducible measurements, would provide the identification of a wide range of chemical compounds simultaneously, disclosing sophisticated frauds or addressing the geographical origin, as well as revealing potential markers for other authentication purposes. The great economic value of high-quality or guaranteed foods demands highly detailed characterization to protect both consumers and producers from frauds. The present scenario suggests metabolomics as the privileged approach of modern analytical studies for the next decades. The large potentiality of high-resolution NMR techniques is here presented through specific applications and using different approaches focused on the authentication process of some foods, like tomato paste, saffron, honey, roasted coffee, and balsamic and traditional balsamic vinegar of Modena, with a particular focus on geographical origin characterization, ageing determination, and fraud detection.

High extinction risk for wild coffee species and implications for coffee sector sustainability

Wild coffee species are critical for coffee crop development and, thus, for sustainability of global coffee production. Despite this fact, the extinction risk and conservation priority status of the world's coffee species are poorly known. Applying IUCN Red List of Threatened Species criteria to all (124) wild coffee species, we undertook a gap analysis for germplasm collections and protected areas and devised a crop wild relative (CWR) priority system. We found that at least 60% of all coffee species are threatened with extinction, 45% are not held in any germplasm collection, and 28% are not known to occur in any protected area. Existing conservation measures, including those for key coffee CWRs, are inadequate. We propose that wild coffee species are extinction sensitive, especially in an era of accelerated climatic change.

Coffea arabica and C. canephora discrimination in roasted and ground coffee from reference material candidates by real-time PCR

To produce specific desirable coffee blends, Coffea arabica and C. canephora are mixed each other, in some cases to suit consumer preference, but in others to reduce production costs. In this scenario, the aim of this work was to evaluate standard candidate reference materials (RMc) for analysis of different blends of roasted and ground coffee. For this purpose, we analyzed different percentages of C. arabica and C. canephora (100:0; 50:50; 25:75; and 0:100, respectively). These RMc samples were developed in a previous study with green coffee beans submitted to medium roasting. In this work, coffee species differentiation (C. arabica and C. canephora) was analyzed by real-time PCR, using specific primers previously developed, called ARA primers. The RMc material with 100% C. canephora did not present amplification, in contrast with the samples containing C. arabica, which all presented amplification. These results indicate the specificity of ARA primers for C. arabica and that the detection system assay can be used as a promising molecular tool to identify and quantify percentages of C. arabica in different coffee blends.