Isotopes as tracers of the Hawaiian coffee-producing regions

The effect of roasting on boron isotope ratio in coffee beans: Implications for provenance studies of roasted coffee

We determined δ11B values of green and roasted coffee beans from 20 locations worldwide and conducted laboratory experiments with the aim to investigate boron isotope fractionation during roasting. Authentic single origin roasted coffees were found to be isotopically lighter than their green bean counterparts, with an average difference of 1.5‰. This isotope fractionation can be explained as arising from partial dissociation of boric acid in capillary water of green beans, where 11B isotopes are preferentially partitioned into molecules of undissociated boric acid and are then volatised during roasting. However, boron isotope fractionation induced by roasting was significantly smaller than between-origin variations in δ11B values of green coffee beans that had the range of ∼54‰. This implies that δ11B isotopic composition of roasted coffee retains the geographical origin information within δ11B values of green beans when regional differences in boron isotopic composition of coffee are considered.

Probabilistic Risk Characterization of Heavy Metals in Peruvian Coffee: Implications of Variety, Region and Processing

Heavy metals are chemical contaminants, toxic, potentially carcinogenic and/or mutagenic, stable, persistent and are of concern in the food chain. The risk to the consumer of the presence of inorganic arsenic (iAs), cadmium (Cd), chromium (Cr), mercury (Hg) and lead (Pb) in five varieties (Bourbon, Típica, Catimor, Caturra and Pache) of parchment coffee from five regions (Amazonas, Cajamarca, Cusco, Huánuco and San Martín) was investigated in this study. A predictive model of the stages of coffee bean hulling, roasting and infusion was built to simulate the process. The results by region showed significant differences in which San Martín had the highest iAs, Cr and Pb values. The variety was only significant for Cr, of which Pache presented the highest concentration. The Cd and Hg values were below the detection limits. The hazard index (HI) was less than 1 for iAs, Cd, Cr and Hg and the combination of margin of exposure and the probability of exceedance (MOE-POE) for Pb indicated that an adverse health effect was not likely. The cancer risk (CR) for iAs and Pb in the 95th percentile was considered as both high and acceptable, respectively.

Stable isotope and trace element analyses with non-linear machine-learning data analysis improved coffee origin classification and marker selection

BACKGROUND

This study investigated the geographical origin classification of green coffee beans from continental to country and regional levels. An innovative approach combined stable isotope and trace element analyses with non-linear machine learning data analysis to improve coffee origin classification and marker selection. Specialty green coffee beans sourced from three continents, eight countries, and 22 regions were analyzed by measuring five isotope ratios (δ¹³ C, δ¹⁵ N, δ¹⁸ O, δ² H, and δ³⁴ S) and 41 trace elements. Partial least squares discriminant analysis (PLS-DA) was applied to the integrated dataset for origin classification.

RESULTS

Origins were predicted well at the country level and showed promise at the regional level, with discriminating marker selection at all levels. However, PLS-DA predicted origin poorly at the continental and Central American regional levels. Non-linear machine learning techniques improved predictions and enabled the identification of a higher number of origin markers, and those that were identified were more relevant. The best predictive accuracy was found using ensemble decision trees, random forest and extreme gradient boost, with accuracies of up to 0.94 and 0.89 for continental and Central American regional models, respectively.

CONCLUSION

The potential for advanced machine learning models to improve origin classification and the identification of relevant origin markers was demonstrated. The decision-tree-based models were superior with their embedded variable identification features and visual interpretation. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Near-infrared reflectance spectroscopy accurately predicted isotope and elemental compositions for origin traceability of coffee

Stable isotope ratios and trace elements are well-established tools that act as signatures of the product's environmental conditions and agricultural processes; but they involve time, money, and environmentally destructive chemicals. In this study, we tested for the first time the potential of near-infrared reflectance spectroscopy (NIR) to estimate/predict isotope and elemental compositions for the origin verification of coffee. Green coffee samples from two continents, 4 countries, and 10 regions were analysed for five isotope ratios (δ¹³C, δ¹⁵N, δ¹⁸O, δ²H, and δ³⁴S) and 41 trace elements. NIR (1100-2400 nm) calibrations were developed using pre-processing with extended multiplicative scatter correction (EMSC) and mean centering and partial-least squares regression (PLS-R). Five elements (Mn, Mo, Rb, B, La) and three isotope ratios (δ¹³C, δ¹⁸O, δ²H) were moderately to well predicted by NIR (R²: 0.69 to 0.93). NIR indirectly measured these parameters by association with organic compounds in coffee. These parameters were related to altitude, temperature and rainfall differences across countries and regions and were previously found to be origin discriminators for coffee.

Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), a Useful Tool in Authenticity of Agricultural Products' and Foods' Origin

Fraudulent practices are the first and foremost concern of food industry, with significant consequences in economy and human's health. The increasing demand for food has led to food fraud by replacing, mixing, blending, and mislabeling products attempting to increase the profits of producers and companies. Consequently, there was the rise of a multidisciplinary field which encompasses a large number of analytical techniques aiming to trace and authenticate the origins of agricultural products, food and beverages. Among the analytical strategies have been developed for the authentication of geographical origin of foodstuff, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) increasingly dominates the field as a robust, accurate, and highly sensitive technique for determining the inorganic elements in food substances. Inorganic elements are well known for evaluating the nutritional composition of food products while it has been shown that they are considered as possible tracers for authenticating the geographical origin. This is based on the fact that the inorganic component of identical food type originating from different territories varies due to the diversity of matrix composition. The present systematic literature review focusing on gathering the research has been done up-to-date on authenticating the geographical origin of agricultural products and foods by utilizing the ICP-MS technique. The first part of the article is a tutorial about food safety/control and the fundaments of ICP-MS technique, while in the second part the total research review is discussed.

Simultaneously Verifying the Original Region of Green and Roasted Coffee Beans by Stable Isotopes and Elements Combined with Random Forest

Simultaneously verifying the original region of green and roasted coffee beans is very important for protecting legal interests of the stakeholder according to the chemical analyzing method. 131 green coffee bean samples are collected from six different original regions and pretreated with three degrees (green, middle, and dark roasted); five stable isotope ratios (δ13C, δ14N, δ18O, δ2H, and δ32S) and twelve elemental contents (Al, Cr, Ni, Zn, Ba, Cu, Na, Mn, Fe, Ca, K, and Mg) of green, middle, and dark roasted coffee bean samples (131×3) were analyzed. Fractionation of stable isotopes and variation of elemental contents were evaluated, only isotope hydrogen (2H) significantly fractionated, and elemental concentrations increased with a certain rate during the roasting process. One-way analysis of variance (ANOVA) was used to compare the stable isotope ratios and elemental concentrations of all coffee bean samples from six different original regions. Random forest (RF) was employed to build a discriminating model for simultaneously verifying the original regions of green and roasted coffee bean samples; this model provided 100% accuracy. Inclusion of this mathematical model for simultaneously verifying the original region of green and roasted coffee beans had powerful distinguishing capability and which will not be influenced by fractionation of hydrogen (2H) and variation of element contents during the roasted process.

Strontium Isotope Systematics of Tenerife Wines (Canary Islands): Tracing Provenance in Ocean Island Terroir

The production of fraudulent goods remains widespread and economically damaging. The high value of the wine industry makes it particularly vulnerable, and a number of geochemical methods have been developed to ensure traceability and identification of origin. Here, strontium (Sr) isotope data on wines from five defined regions in Tenerife (Canary Islands, Spain) show that the young volcanic geology imparts a clearly identifiable low 87Sr/86Sr signature (<0.7072). These values discriminate Tenerife wines from mainland Spanish and continental European produce, as these are much more radiogenic in general. However, unlike continental wine regions, wines from Tenerife show small but ubiquitous enrichments in 87Sr/86Sr above what is expected in the soils. Bentonite addition has not affected the 87Sr/86Sr signatures, with white wines at lower Sr concentrations than red wines in all regions. A number of natural contributions to the terroir are evaluated in relation to Tenerife’s unique combination of geology and geography. Atmospheric precipitation (rainfall) is likely a dominant influence on Sr isotope systematics in northern Denominación de Origen regions, and evaporation may play a role in buffering signatures in southern regions. Other natural additions of 87Sr are not precluded at a local scale, given the large range in climatic conditions of island terroir and known input of mineral dust from Africa. Despite natural explanations affecting the overall small shift observed, there are clear outliers with considerably higher 87Sr/86Sr and Sr concentration. This confirms the utility of Sr isotope systematics for oceanic-island viticulture and demonstrates the use of young volcanic soils for tracing natural inputs that may be masked in other regions.

Coffee Infusions: Can They Be a Source of Microelements with Antioxidant Properties?

Coffee is a beverage that is very popular all over the world. Its pro-health effect has been demonstrated in many publications. This drink can counteract the effects of oxidative stress thanks to its antioxidant properties. The aim of this study was to collect data on the content of microelements with antioxidant activity (manganese, zinc, copper, iron) in coffee infusions, taking into account various factors. The study considered publications from the years 2000–2020 found in Google Scholar and PubMed databases. It was noted that coffee can provide up to 13.7% of manganese requirements per serving, up to 4.0% and 3.1% of zinc requirements for women and men, up to 2.7% and 2.1% of copper requirements for women and men, and up to 0.4% and 0.6% of iron requirements for women and men. Coffee infusions can also be a source of fluoride (up to 2.5%), chromium (up to 0.4% of daily intake for women and 0.2% for men), and cobalt (up to 0.1%). There are no data in the literature regarding the content of selenium in coffee infusions. The origin of coffee beans and the type of water used (especially regarding fluoride) may have an impact on the content of minerals in infusions. The brewing method does not seem to play an important role. As it is a very popular beverage, coffee can additionally enrich the diet with such micronutrients as manganese, zinc, and copper. This seems beneficial due to their antioxidant properties, however the bioavailability of these elements of coffee should be taken into account. It seems necessary to carry out more research in this area.

The Provenance of Slovenian Milk Using 87Sr/86Sr Isotope Ratios

This work presents the first use of Sr isotope ratios for determining the provenance of bovine milk from different regions of Slovenia. The analytical protocol for the determination of ⁸⁷Sr/⁸⁶Sr isotope ratio was optimised and applied to authentic milk samples. Considerable variability of ⁸⁷Sr/⁸⁶Sr ratios found in Slovenian milk reflects the substantial heterogeneity of the geological background of its origin. The results, although promising, cannot discount possible inter-annual or annual variation of the Sr isotopic composition of milk. The ⁸⁷Sr/⁸⁶Sr ratios of groundwater and surface waters are in good correlation with milk, indicating that the Sr isotopic fingerprint in milk is reflective of cow drinking water. The ⁸⁷Sr/⁸⁶Sr ratio has the potential to distinguish between different milk production areas as long as these areas are characterised by geo-lithology. Discriminant analysis (DA) incorporating the elemental composition and stable isotopes of light elements showed that ⁸⁷Sr/⁸⁶Sr ratio together with δ¹³C_cas and δ¹⁵N_cas values have the main discrimination power to distinguish the Quaternary group (group 6) from the others. Group 1 (Cretaceous: Carbonate Rocks and Flysch) is associated with Br content, 1/Sr and δ¹⁸O_w values. The overall prediction ability was found to be 63.5%. Pairwise comparisons using OPLS-DA confirmed that diet and geologic parameters are important for the separation.

Achieving Food Authenticity and Traceability Using an Analytical Method Focusing on Stable Isotope Analysis

High-value agricultural products are characterized by the geographical conditions of the production areas such as climatic and soil conditions. These products are protected by the geographical indication (GI) protection system, which has been introduced in more than 100 countries. Because GI products are expensive in the market, products are often mislabeled as GI. Thus, there is an urgent need for the development of analytical methods that enable the tracing of geographical origins of food materials. Stable isotope analysis is used to trace the geographical origin of food materials. In this study, we review the applications for tracing the geographical origin of agricultural products (especially rice, beef, and honey) focusing on an analytical method for analyzing stable isotopes (δD, δ¹³C, δ¹⁵N, δ¹⁸O, and δ³⁴S).

A predictive spatial model for roasted coffee using oxygen isotopes of α-cellulose

RATIONALE

Fraudulent region-of-origin labeling is a concern for high-value, globally traded commodities such as coffee. The oxygen isotope ratio of cellulose is a useful geographic tracer, as it integrates climate and source water signals. A predictive spatial model ("isoscape") of the δ¹⁸ O values of coffee bean cellulose is generated to evaluate coffee region-of-origin claims.

METHODS

The oxygen isotope ratio of α-cellulose extracted from roasted coffee beans was measured via high-temperature conversion elemental analyzer/isotope ratio mass spectrometry (TC-EA/IRMS) and used to calculate the δ¹⁸ O value of coffee bean water. The ¹⁸ O enrichment of coffee bean water relative to the δ¹⁸ O value of local precipitation was modeled as a function of local temperature and humidity. This function was incorporated into a mechanistic model of cellulose δ¹⁸ O values to predict the δ¹⁸ O values of coffee bean cellulose across coffee-producing regions globally.

RESULTS

The δ¹⁸ O values of analyzed coffee bean cellulose ranged from approximately +22‰ to +42‰ (V-SMOW). As expected, coffees grown in the same region tended to have similar isotope ratios, and the δ¹⁸ O value of coffee bean cellulose was generally higher than the δ¹⁸ O value of modeled stem cellulose for the region. Modeled δ¹⁸ O values of coffee cellulose were within ±2.3‰ of the measured δ¹⁸ O value of coffee cellulose.

CONCLUSIONS

The oxygen isotope ratio of coffee bean cellulose is a useful indicator of region-of-origin and varies predictably in response to climatic factors and precipitation isotope ratios. The isoscape of coffee bean cellulose δ¹⁸ O values from this study provides a quantitative tool that can be applied to region-of-origin verification of roasted coffee at the point-of-sale.

Fully Automated Identification of Coffee Species and Simultaneous Quantification of Furfuryl Alcohol Using NMR Spectroscopy

BACKGROUND

Coffee is a popular beverage with two species, Coffea canephora and C. arabica, being commercially exploited. The quality and commercial value of coffee is dependent on species and processing. C. arabica typically obtains a higher price on the market compared to C. canephora. Coffee beans undergo roasting during processing, resulting in the formation of flavor compounds including furfuryl alcohol which has been classified by the International Agency for Research on Cancer as possibly carcinogenic to humans (Group 2B).

OBJECTIVE

The aim of this study was to identify coffee species and other properties using nuclear magnetic resonance (NMR) spectroscopy, specifically to conduct quantification of the roasting process contaminant furfuryl alcohol.

METHOD

The quantification of furfuryl alcohol was performed from the NMR spectra using the pulse length-based concentration (PULCON) methodology. Prior to NMR analysis, samples were extracted using deuterated chloroform.

RESULTS

Roasting experiments identified the maximum roasting temperature to be the most significant factor in the formation of furfuryl alcohol. Among the coffee species, C. canephora was found to contain a relatively lower amount of furfuryl alcohol compared to C. arabica. The roasting of wet processed coffee resulted in higher contents of furfuryl alcohol. Geographical origin and variety within species had no influence on the furfuryl alcohol content.

CONCLUSION

Validation results show that NMR spectroscopy is fit-for-purpose to obtain targeted information of coffee samples.

HIGHLIGHTS

The PULCON NMR methodology allows a simple, rapid and accurate determination of constituents of coffee.

Validation of a Quantitative Proton Nuclear Magnetic Resonance Spectroscopic Screening Method for Coffee Quality and Authenticity (NMR Coffee Screener)

Monitoring coffee quality as a means of detecting and preventing economically motivated fraud is an important aspect of international commerce today. Therefore, there is a compelling need for rapid high throughput validated analytical techniques such as quantitative proton nuclear magnetic resonance (NMR) spectroscopy for screening and authenticity testing. For this reason, we sought to validate an ¹H NMR spectroscopic method for the routine screening of coffee for quality and authenticity. A factorial experimental design was used to investigate the influence of the NMR device, extraction time, and nature of coffee on the content of caffeine, 16-O-methylcafestol (OMC), kahweol, furfuryl alcohol, and 5-hydroxymethylfurfural (HMF) in coffee. The method was successfully validated for specificity, selectivity, sensitivity, and linearity of detector response. The proposed method produced satisfactory precision for all analytes in roasted coffee, except for kahweol in canephora (robusta) coffee. The proposed validated method may be used for routine screening of roasted coffee for quality and authenticity control (i.e., arabica/robusta discrimination), as its applicability was demonstrated during the recent OPSON VIII Europol-Interpol operation on coffee fraud control.

Characterization of Brazilian coffee based on isotope ratio mass spectrometry (δ13C, δ18O, δ2H, and δ15N) and supervised chemometrics

Authentication of ground coffee has become an important issue because of fraudulent activities in the sector. In the current work, sixty-seven Brazilian coffees produced in different geographical origins using organic (ORG, n = 25) and conventional (CONV, n = 42) systems were analyzed for their stable isotope ratios (δ¹³C, δ¹⁸O, δ²H, and δ¹⁵N). Data were analyzed by inferential analysis to compare the factors whereas linear discriminant analysis (LDA), k-nearest neighbors (k-NN), and support vector machines (SVM) were used to classify the coffees based on their origin. ORG and CONV cultivated coffees could not be differentiated according to C stable isotope ratio (δ¹³C; p = 0.204), but ORG coffees presented higher values of the N stable isotope ratio (δ¹⁵N; p = 0.0006). k-NN presented the best classification results for both ORG and CONV coffees (87% and 67%, respectively). SVM correctly classified coffees produced in São Paulo (75% accuracy), while LDA correctly classified 71% of coffees produced in Minas Gerais.

GC-MS profiling of fatty acids in green coffee (Coffea arabica L.) beans and chemometric modeling for tracing geographical origins from Ethiopia

BACKGROUND

This study was aimed at the development of objective analytical method capable of verifying the production region of the coffee beans. One hundred samples of green coffee (Coffea arabica L.) beans from the major producing regions, comprising various sub-regional types, were studied for variations in their fatty acid compositions by using gas chromatography coupled with mass spectrometry. Principal component analysis (PCA) was used to visualize data trends. Linear discriminant analysis (LDA) was used to construct classification models.

RESULTS

Twenty-one different fatty acids were detected in all of the samples. The total fatty acid content varied from 83 to 204 g kg^-1 across the regions. Oleic, linoleic, palmitic, stearic and arachidic acids were identified as the most discriminating compounds among the production regions. The recognition and prediction abilities of the LDA model for classification at regional level were 95% and 92%, respectively, and 92% and 85%, respectively, at sub-regional level.

CONCLUSION

Fatty acids contain adequate information for use as descriptors of the cultivation region of coffee beans. Chemometric methods based on fatty acid composition can be used to detect fraudulently labeled coffees, with regard to the production region. These can benefit the coffee production market by providing consumers with products of the expected quality. © 2019 Society of Chemical Industry.

Differentiating the geographical origin of Ethiopian coffee using XRF- and ICP-based multi-element and stable isotope profiling

To test the potential of different analytical tools to determine the geographical origin of Ethiopian coffee, 103 green arabica coffee samples from four coffee regions in Ethiopia were subjected to multi-elements and δ¹³C, δ¹⁵N and δ¹⁸O determinations. Multi-elements were determined by using inductively coupled plasma (ICP)- and X-ray fluorescence spectrometry (XRF)-based techniques, and δ¹³C, δ¹⁵N and δ¹⁸O were determined by using elemental analyzer-isotope ratio mass spectrometry. Using linear discriminant analysis, XRF-based multi-elements with and without δ¹³C appeared to be most effective in discriminating the geographical origin of coffee, giving higher classification accuracy (89 and 86%, respectively) than ICP-based multi-elements with and without stable isotopes (80%, each). These results demonstrate the potential of XRF-based multi-element profiling as a relatively fast and low-cost tool to trace the geographical origin of Ethiopian coffee. All together this study offers the proof of concept for a promising method that, upon standardization, could be used for coffee provenance authentication and fraud detection.

Comparison of Attenuated Total Reflectance Mid-Infrared, Near Infrared, and 1H-Nuclear Magnetic Resonance Spectroscopies for the Determination of Coffee's Geographical Origin

The sensorial properties of Colombian coffee are renowned worldwide, which is reflected in its market value. This raises the threat of fraud by adulteration using coffee grains from other countries, thus creating a demand for robust and cost-effective methods for the determination of geographical origin of coffee samples. Spectroscopic techniques such as Nuclear Magnetic Resonance (NMR), near infrared (NIR), and mid-infrared (mIR) have arisen as strong candidates for the task. Although a body of work exists that reports on their individual performances, a faithful comparison has not been established yet. We evaluated the performance of ¹H-NMR, Attenuated Total Reflectance mIR (ATR-mIR), and NIR applied to fraud detection in Colombian coffee. For each technique, we built classification models for discrimination by species (C. arabica versus C. canephora (or robusta)) and by origin (Colombia versus other C. arabica) using a common set of coffee samples. All techniques successfully discriminated samples by species, as expected. Regarding origin determination, ATR-mIR and ¹H-NMR showed comparable capacity to discriminate Colombian coffee samples, while NIR fell short by comparison. In conclusion, ATR-mIR, a less common technique in the field of coffee adulteration and fraud detection, emerges as a strong candidate, faster and with lower cost compared to ¹H-NMR and more discriminating compared to NIR.

Negative correlation between altitudes and oxygen isotope ratios of seeds: exploring its applicability to assess vertical seed dispersal

Vertical seed dispersal, which plays a key role in plant escape and/or expansion under climate change, was recently evaluated for the first time using negative correlation between altitudes and oxygen isotope ratio of seeds. Although this method is innovative, its applicability to other plants is unknown. To explore the applicability of the method, we regressed altitudes on δ18O of seeds of five woody species constituting three families in temperate forests in central Japan. Because climatic factors, including temperature and precipitation that influence δ18O of plant materials, demonstrate intensive seasonal fluctuation in the temperate zone, we also evaluated the effect of fruiting season of each species on δ18O of seeds using generalized linear mixed models (GLMM). Negative correlation between altitudes and δ18O of seeds was found in four of five species tested. The slope of regression lines tended to be lower in late-fruiting species. The GLMM analysis revealed that altitudes and date of fruiting peak negatively affected δ18O of seeds. These results indicate that the estimation of vertical seed dispersal using δ18O of seeds can be applicable for various species, not just confined to specific taxa, by identifying the altitudes of plants that produced seeds. The results also suggest that the regression line between altitudes and δ18O of seeds is rather species specific and that vertical seed dispersal in late-fruiting species is estimated at a low resolution due to their small regression slopes. A future study on the identification of environmental factors and plant traits that cause a difference in δ18O of seeds, combined with an improvement of analysis, will lead to effective evaluation of vertical seed dispersal in various species and thereby promote our understanding about the mechanism and ecological functions of vertical seed dispersal.

Elemental composition of green coffee and its contribution to dietary intake

The concentration of twenty-seven elements (Li, Be, B, Mg, Al, P, K, Ca, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Sn, Sb, Ba, Hg, Pb, Bi, Th, and U) in green coffee samples and their infusions were determined by using inductively coupled plasma-mass spectrometry (ICP-MS). Prior to analysis, green coffee samples were prepared by microwave digestion, while infusions were analyzed without any pre-treatment. The accuracy and precision of the proposed methods were verified by recovery experiments. Considering samples; K, Cu, and Al had the highest mean concentrations with 6714.5μgg(-1), 12.1μgg(-1), and 25.9μgg(-1) among major, trace and toxic elements, respectively. The impact of brewing type on leachability of elements was also studied and the results outlined that mean leachability of elements to Turkish coffee were greater than to mud coffee. Furthermore, dietary element intakes through green coffee consumption were also estimated. This is the first study presenting wide range of elements in green coffee brews and calculating dietary intakes.

Classification of Coffee Beans by GC-C-IRMS, GC-MS, and (1)H-NMR

In a previous work using (1)H-NMR we reported encouraging steps towards the construction of a robust expert system for the discrimination of coffees from Colombia versus nearby countries (Brazil and Peru), to assist the recent protected geographical indication granted to Colombian coffee in 2007. This system relies on fingerprints acquired on a 400 MHz magnet and is thus well suited for small scale random screening of samples obtained at resellers or coffee shops. However, this approach cannot easily be implemented at harbour's installations, due to the elevated operational costs of cryogenic magnets. This limitation implies shipping the samples to the NMR laboratory, making the overall approach slower and thereby more expensive and less attractive for large scale screening at harbours. In this work, we report on our attempt to obtain comparable classification results using alternative techniques that have been reported promising as an alternative to NMR: GC-MS and GC-C-IRMS. Although statistically significant information could be obtained by all three methods, the results show that the quality of the classifiers depends mainly on the number of variables included in the analysis; hence NMR provides an advantage since more molecules are detected to obtain a model with better predictions.

Elemental profiling and geographical differentiation of Ethiopian coffee samples through inductively coupled plasma-optical emission spectroscopy (ICP-OES), ICP-mass spectrometry (ICP-MS) and direct mercury analyzer (DMA)

This study was aimed to establish the elemental profiling and provenance of coffee samples collected from eleven major coffee producing regions of Ethiopia. A total of 129 samples were analyzed for forty-five elements using inductively coupled plasma (ICP)-optical emission spectroscopy (OES), ICP-mass spectrometry (MS) and direct mercury analyzer (DMA). Among the macro elements, K showed the highest levels whereas Fe was found to have the lowest concentration values. In all the samples, Ca, K, Mg, P and S contents were statistically significant (p<0.05). Micro elements showed the concentrations order of: Mn>Cu>Sr>Zn>Rb>Ni>B. Contents of the trace elements were lower than the permissible standard values. Inter-regions differentiation by cluster analysis (CA), linear discriminant analysis (LDA) and principal component analysis (PCA) showed that micro and trace elements are the best chemical descriptors of the analyzed coffee samples.

Long-term elevated air [CO2 ] strengthens photosynthetic functioning and mitigates the impact of supra-optimal temperatures in tropical Coffea arabica and C. canephora species

The tropical coffee crop has been predicted to be threatened by future climate changes and global warming. However, the real biological effects of such changes remain unknown. Therefore, this work aims to link the physiological and biochemical responses of photosynthesis to elevated air [CO2 ] and temperature in cultivated genotypes of Coffea arabica L. (cv. Icatu and IPR108) and Coffea canephora cv. Conilon CL153. Plants were grown for ca. 10 months at 25/20°C (day/night) and 380 or 700 μl CO2 l(-1) and then subjected to temperature increase (0.5°C day(-1) ) to 42/34°C. Leaf impacts related to stomatal traits, gas exchanges, C isotope composition, fluorescence parameters, thylakoid electron transport and enzyme activities were assessed at 25/20, 31/25, 37/30 and 42/34°C. The results showed that (1) both species were remarkably heat tolerant up to 37/30°C, but at 42/34°C a threshold for irreversible nonstomatal deleterious effects was reached. Impairments were greater in C. arabica (especially in Icatu) and under normal [CO2 ]. Photosystems and thylakoid electron transport were shown to be quite heat tolerant, contrasting to the enzymes related to energy metabolism, including RuBisCO, which were the most sensitive components. (2) Significant stomatal trait modifications were promoted almost exclusively by temperature and were species dependent. Elevated [CO2 ], (3) strongly mitigated the impact of temperature on both species, particularly at 42/34°C, modifying the response to supra-optimal temperatures, (4) promoted higher water-use efficiency under moderately higher temperature (31/25°C) and (5) did not provoke photosynthetic downregulation. Instead, enhancements in [CO2 ] strengthened photosynthetic photochemical efficiency, energy use and biochemical functioning at all temperatures. Our novel findings demonstrate a relevant heat resilience of coffee species and that elevated [CO2 ] remarkably mitigated the impact of heat on coffee physiology, therefore playing a key role in this crop sustainability under future climate change scenarios.

Isotopic and Elemental Composition of Roasted Coffee as a Guide to Authenticity and Origin

This study presents the stable isotopic and elemental compositions of single-origin, roasted coffees available to retail consumers. The δ(13)C, δ(15)N, and δ(18)O compositions were in agreement with those previously reported for green coffee beans. The δ(15)N composition was seen to be related to organic cultivation, reflected in both δ(2)H and δ(18)O compositions. The δ(13)C composition of extracted caffeine differed little from that of the bulk coffee. Stepwise discriminant analysis with jackknife tests, using isotopic and elemental data, provided up to 77% correct classification of regions of production. Samples from Africa and India were readily classified. The wide range in both isotopic and elemental compositions of samples from other regions, specifically Central/South America, resulted in poor discrimination between or within these regions. Simpler X-Y and geo-spatial plots of the isotopic data provided effective visual means to distinguish between coffees from different regions.

Steep spatial gradients of volcanic and marine sulfur in Hawaiian rainfall and ecosystems

Sulfur, a nutrient required by terrestrial ecosystems, is likely to be regulated by atmospheric processes in well-drained, upland settings because of its low concentration in most bedrock and generally poor retention by inorganic reactions within soils. Environmental controls on sulfur sources in unpolluted ecosystems have seldom been investigated in detail, even though the possibility of sulfur limiting primary production is much greater where atmospheric deposition of anthropogenic sulfur is low. Here we measure sulfur isotopic compositions of soils, vegetation and bulk atmospheric deposition from the Hawaiian Islands for the purpose of tracing sources of ecosystem sulfur. Hawaiian lava has a mantle-derived sulfur isotopic composition (δ(34)S VCDT) of -0.8‰. Bulk deposition on the island of Maui had a δ(34)S VCDT that varied temporally, spanned a range from +8.2 to +19.7‰, and reflected isotopic mixing from three sources: sea-salt (+21.1‰), marine biogenic emissions (+15.6‰), and volcanic emissions from active vents on Kilauea Volcano (+0.8‰). A straightforward, weathering-driven transition in ecosystem sulfur sources could be interpreted in the shift from relatively low (0.0 to +2.7‰) to relatively high (+17.8 to +19.3‰) soil δ(34)S values along a 0.3 to 4100 ka soil age-gradient, and similar patterns in associated vegetation. However, sub-kilometer scale spatial variation in soil sulfur isotopic composition was found along soil transects assumed by age and mass balance to be dominated by atmospheric sulfur inputs. Soil sulfur isotopic compositions ranged from +8.1 to +20.3‰ and generally decreased with increasing elevation (0-2000 m), distance from the coast (0-12 km), and annual rainfall (180-5000 mm). Such trends reflect the spatial variation in marine versus volcanic inputs from atmospheric deposition. Broadly, these results illustrate how the sources and magnitude of atmospheric deposition can exert controls over ecosystem sulfur biogeochemistry across relatively small spatial scales.

Determination of the source of bioavailable Sr using ⁸⁷Sr/⁸⁶Sr tracers: a case study of hot pepper and rice

The geographical origin of agricultural products has been intensively studied, but links between agricultural products and the environments are poorly established. Soils, water (streamwater and groundwater), and plants (hot pepper, Capsicum annuum; and rice, Oryza sativa) were collected from all regions of South Korea and measured Sr isotope ratios ((87)Sr/(86)Sr). Sequential leaching of soil showed that Sr in the exchangeable and carbonate fractions (bioavailable) had a lower (87)Sr/(86)Sr ratio than that in the silicate fraction, consistent with a low (87)Sr/(86)Sr ratio in the plant. Although the bedrock-soil-water-plant system is closely linked, statistical analysis indicated that (87)Sr/(86)Sr ratios of the plant showed the greatest agreement with those of water and the exchangeable fraction of soil. This study is the first report of (87)Sr/(86)Sr isoscapes in South Korea and first demonstrates that the agricultural product is strongly linked with the exchangeable fraction of soil and water.

Photosynthesis of Quercus suber is affected by atmospheric NH3 generated by multifunctional agrosystems

Montados are evergreen oak woodlands dominated by Quercus species, which are considered to be key to biodiversity conservation and ecosystem services. This ecosystem is often used for cattle breeding in most regions of the Iberian Peninsula, which causes plants to receive extra nitrogen as ammonia (NH(3)) through the atmosphere. The effect of this atmospheric NH(3) (NH(3atm)) on ecosystems is still under discussion. This study aimed to evaluate the effects of an NH(3atm) concentration gradient downwind of a cattle barn in a Montado area. Leaves from the selected Quercus suber L. trees along the gradient showed a clear influence of the NH(3) on δ(13)C, as a consequence of a strong limitation on the photosynthetic machinery by a reduction of both stomatal and mesophyll conductance. A detailed study of the impact of NH(3atm) on the photosynthetic performance of Q. suber trees is presented, and new mechanisms by which NH(3) affects photosynthesis at the leaf level are suggested.

Geographic determination of coffee beans using multi-element analysis and isotope ratios of boron and strontium

This study aims to evaluate the feasibility of using chemical and isotopic compositions of coffee beans to identify their geographic origins. Twenty-one Coffea arabica beans collected from 14 countries in 3 major coffee-producing regions, Africa, America and Asia, were analysed for multi-element of B, Rb, Sr, Ba, Fe, Mn and Zn, as well as isotopic compositions of B and Sr. Our results demonstrate that the geographic origin of coffee beans could be classified based on concentrations of Rb, Sr and Ba. However, the isotope ratios of B and Sr provide more sensitive information for the growth localities. Combined with literature data, this study indicates that B and Sr isotopes are excellent indicators of the origin of coffee beans.

Using elemental profiles and stable isotopes to trace the origin of green coffee beans on the global market

A broad elemental profile incorporating 54 elements (Li, Be, B, Na, Mg, Al, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Y, Mo, Pd, Ag, Cd, Sn, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er, Tm, Yb, Re, Ir, Pt, Au, Hg, Tl, Pb, Bi and U) in combination with δ(2) H, δ(13) C, δ(15) N and δ(18) O was used to characterise the composition of 62 green arabica (Coffea arabica) and robusta (Coffea canephora) coffee beans grown in South and Central America, Africa and Asia, the four most internationally renowned areas of production. The δ(2) H, Mg, Fe, Co and Ni content made it possible to correctly assign 95% of green coffee beans to the appropriate variety. Canonical discriminant analysis, performed using δ(13) C, δ(15) N, δ(18) O, Li, Mg, P, K, Mn, Co, Cu, Se, Y, Mo, Cd, La and Ce correctly traced the origin of 98% of coffee beans.