Coffee Species Research Articles

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.

Establishment of Discrimination System Using Multivariate Analysis of FT-IR Spectroscopy Data from Different Species of Coffee (<i>C. arabica</i>)

Establishment of Discrimination System Using Multivariate Analysis of FT-IR Spectroscopy Data from Different Species of Coffee (<i>C. arabica</i>)

New plant associations for Monalonion velezangeli (Hemiptera: Miridae) in green urban areas of Bogotá (Colombia)

Monalonion velezangeli Carvalho and Costa (Hemiptera: Miridae) es un mírido polífago reconocido como una de las especies plaga más importantes del café y el aguacate en regiones rurales de Colombia. M. velezangeli es reportado por primera vez en áreas verdes urbanas en la cordillera de los Andes en la ciudad de Bogotá (Colombia). Los especímenes fueron recolectados en ocho especies de árboles plantados en la ciudad, de los cuales cinco representan nuevas asociaciones de M. velezangeli. La especie Schinus molle L. (Anacardiaceae) es por primera vez reportada como nueva planta hospedera afectada por M. velezangeli bajo las condiciones urbanas.

Variability of single bean coffee volatile compounds of Arabica and robusta roasted coffees analysed by SPME-GC-MS

We report on the analysis of volatile compounds by SPME-GC-MS for individual roasted coffee beans. The aim was to understand the relative abundance and variability of volatile compounds between individual roasted coffee beans at constant roasting conditions. Twenty-five batches of Arabica and robusta species were sampled from 13 countries, and 10 single coffee beans randomly selected from each batch were individually roasted in a fluidised-bed roaster at 210 °C for 3 min. High variability (CV = 14.0–53.3%) of 50 volatile compounds in roasted coffee was obtained within batches (10 beans per batch). Phenols and heterocyclic nitrogen compounds generally had higher intra-batch variation, while ketones were the most uniform compounds (CV < 20%). The variation between batches was much higher, with the CV ranging from 15.6 to 179.3%. The highest variation was observed for 2,3-butanediol, 3-ethylpyridine and hexanal. It was also possible to build classification models based on geographical origin, obtaining 99.5% and 90.8% accuracy using LDA or MLR classifiers respectively, and classification between Arabica and robusta beans. These results give further insight into natural variation of coffee aroma and could be used to obtain higher quality and more consistent final products. Our results suggest that coffee volatile concentration is also influenced by other factors than simply the roasting degree, especially green coffee composition, which is in turn influenced by the coffee species, geographical origin, ripening stage and pre- and post-harvest processing.

Sensory characterization and acceptance of coffee brews of C. arabica and C. canephora blended with steamed defective coffee.

Steam treatment has been reported as an alternative to improve the cup quality of coffee; in this research, it was applied to C. canephora defective coffee. The aim of the study was to evaluate the sensory perception of steamed defective C. canephora coffee (SDC) in roasted coffee blends, by Flash Profile and acceptance tests. SDC was produced by steam treatment (5 bar, 16 min) and a standardized roasting process was applied to all coffees. Four samples were prepared as follows: AB (100% C. arabica), CB (100% C. canephora), ASDB and CSDB, both blends with 50% of SDC and C. arabica or C. canephora, respectively. Coffee brews were prepared through percolation (50 g coffee/500 mL water at 92 °C). Coffee species were more relevant in sensory discrimination of the brews than SDC addition. AB and ASDB were characterized as having brown color, fruity/herbal/green bean aroma and coffee/residual coffee flavor. CB and CSDB were described as viscous, with foam, black color, bitter taste, and aroma/taste related to the roasting process. With SDC addition, typical sensory characteristics of each species were maintained, but the intensity of the attributes was reduced. Coffee brews blends with 50% SDC C. canephora are well accepted.

Physiological and Agronomic Performance of the Coffee Crop in the Context of Climate Change and Global Warming: A Review.

Coffee is one of the most important global crops and provides a livelihood to millions of people living in developing countries. Coffee species have been described as being highly sensitive to climate change, as largely deduced from modeling studies based on predictions of rising temperatures and changing rainfall patterns. Here, we discuss the physiological responses of the coffee tree in the context of present and ongoing climate changes, including drought, heat, and light stresses, and interactions between these factors. We also summarize recent insights on the physiological and agronomic performance of coffee at elevated atmospheric CO2 concentrations and highlight the key role of CO2 in mitigating the harmful effects of heat stress. Evidence is shown suggesting that warming, per se, may be less harmful to coffee suitability than previously estimated, at least under the conditions of an adequate water supply. Finally, we discuss several mitigation strategies to improve crop performance in a changing world.

Qualitative carbonyl profile in coffee beans through GDME-HPLC-DAD-MS/MS for coffee preliminary characterization

In this work, an analytical methodology for volatile carbonyl compounds characterization in green and roasted coffee beans was developed. The methodology relied on a recent and simple sample preparation technique, gas diffusion microextraction for extraction of the samples' volatiles, followed HPLC-DAD-MS/MS analysis. The experimental conditions in terms of extraction temperature and extraction time were studied. A profile for carbonyl compounds was obtained for both arabica and robusta coffee species (green and roasted samples). Twenty-seven carbonyl compounds were identified and further discussed, in light of reported literature, with different coffee characteristics: coffee ageing, organoleptic impact, presence of defective beans, authenticity, human's health implication, post-harvest coffee processing and roasting. The applied methodology showed to be a powerful analytical tool to be used for coffee characterization as it measures marker compounds of different coffee characteristics.

Population genomic footprints of host adaptation, introgression and recombination in coffee leaf rust.

Coffee leaf rust, caused by Hemileia vastatrix (Hv), represents the biggest threat to coffee production worldwide and ranks amongst the most serious fungal diseases in history. Despite a recent series of outbreaks and emergence of hypervirulent strains, the population evolutionary history and potential of this pathogen remain poorly understood. To address this issue, we used restriction site-associated DNA sequencing (RADseq) to generate ∼19000 single nucleotide polymorphisms (SNPs) across a worldwide collection of 37 Hv samples. Contrary to the long-standing idea that Hv represents a genetically unstructured and cosmopolitan species, our results reveal the existence of a cryptic species complex with marked host tropism. Using phylogenetic and pathological data, we show that one of these lineages (C3) infects almost exclusively the most economically valuable coffee species (tetraploids that include Coffea arabica and interspecific hybrids), whereas the other lineages (C1 and C2) are severely maladapted to these hosts, but successfully infect diploid coffee species. Population dynamic analyses suggest that the C3 group may be a recent 'domesticated' lineage that emerged via host shift from diploid coffee hosts. We also found evidence of recombination occurring within this group, which could explain the high pace of pathotype emergence despite the low genetic variation. Moreover, genomic footprints of introgression between the C3 and C2 groups were discovered and raise the possibility that virulence factors may be quickly exchanged between groups with different pathogenic abilities. This work advances our understanding of the evolutionary strategies used by plant pathogens in agro-ecosystems with direct and far-reaching implications for disease control.

Birds and beans: Comparing avian richness and endemism in arabica and robusta agroforests in India\u2019s Western Ghats

Coffee is a major tropical commodity crop that can provide supplementary habitat for native wildlife. In Asia, coffee production is an increasingly important driver of landscape transformation and shifts between different coffee species is a major dimension of agroforestry trends. Yet few studies have compared the ecological impacts of conversion between different coffee species. We evaluated whether or not the two species of coffee grown globally—Coffea arabica and C. canephora (denoted “robusta”)—had equivalent avian conservation value in the Western Ghats, India, where robusta production has become increasingly dominant. We found that habitat specialist and functional guild diversity was higher in arabica, and that arabica was more profitable. However, robusta farms generally supported the same or slightly higher abundances of habitat specialists and functional guilds, largely due to dense canopy and landscape-level forest cover. Farming practices, chiefly pesticide use, may affect the suitability of coffee agroforests as habitat for avian specialists, and at present, robusta farmers tended to use less pesticide. Given future projections for arabica to robusta conversion in tropical Asia, our study indicates that certification efforts should prioritize maintaining native canopy shade trees and forest cover to ensure that coffee landscapes can continue providing biodiversity benefits.

Neutron activation analysis of major and trace elements in Arabica and Robusta coffee beans samples consumed in Algeria

Abstract The Algerian neutron activation analysis laboratory is highly involved in nutrition applications in the framework of research activities using the Es-Salam research reactor. The main objective of this work is to contribute, by using nuclear analytical techniques, for studying a large number of natural food samples consumed in Algeria related to nutrition and human health. The present study focuses on the analysis of the most popular beans consumed worldwide, namely, the coffee species of Arabica and Robusta, based on the international markets. Chemical content of samples was assessed by instrumental neutron activation analysis (INAA) and k 0-INAA techniques, through the irradiation of samples during 6 h at a thermal neutron flux of 4.5×1013cm−2s−1 of Es-Salam research reactor. A total of 17 elements were assessed such as, (Br, Ca, Ce, Co, Cr, Cs, Fe, K, La, Na, Rb, Sc, Sm, Sr, Zn, Lu and Th) obtained by using INAA and k 0-INAA methods, While we used the radiochemical neutron activation analysis (RNAA and k 0-RNAA) to determine Selenium at low level concentrations, the accuracy of the method was evaluated by analyzing CRM and SRM. QC/QA was evaluated by using the statistical parameter U-score. Results were compared with those obtained for samples from Brazilian, Caribbean, Indian and Kenyan coffee beans reported in the literature. The daily intake of essentials and toxic elements was determined and compared with the recommended values. The probable cumulative intake of toxic elements was found to be well below the tolerance limits.

Development of a rapid and efficient DNA-based method to detect and quantify adulterations in coffee (Arabica versus Robusta)

Worldwide appreciated beverage, “Arabica” and “Robusta” coffee produced from Coffea arabica and C. canephora respectively, represents a high economical value product. Arabica coffee is generally sold at a higher price than Robusta coffee. As both intentional and accidental adulterations of Arabica with Robusta are frequent, a reliable, inexpensive, and high-throughput adulteration detection technology is required for the coffee industry. We developed a DNA-based authentication method that overcomes limitations of metabolic profiling of Robusta and Arabica coffees. The identification of Arabica and Robusta coffee species, as well as the quantification of their relative proportion in blends were performed by High Resolution Melting (HRM) analysis on green and roasted coffee products. For a more sensitive detection method, chloroplastic rather than nuclear genetic variations were targeted between Coffea species. By the developed method, the Coffea species of origin can be quickly differentiated and in case of adulteration, the percentage can be determined.

First Report of Colletotrichum fructicola Causing Anthracnose on Camellia sinensis in Guangdong Province, China

Colletotrichum Corda is one of the most important plant pathogens that has a wide range of hosts including apple (Velho et al. 2016), coffee (Prihastuti et al. 2009), and many other species of plants. Meanwhile, anthracnose on tea plants (Camellia sinensis) caused by Colletotrichum spp. is one of the most severe diseases. During 2014 and 2015, a leaf and twig blight occurred with a disease incidence of 20 to 40% on tea plants in growing regions of Jiaoling County, in Guangdong Province. Symptoms began as small, water-soaked lesions on young leaves, and later became larger, semicircular or irregular, dark brown, reddish-brown at the margin. At later stages, the lesions became grayish white with black acervuli on surface. Six Colletotrichum-like isolates were isolated from symptomatic leaves on PDA, and pure cultures were obtained by single-spore isolation. All isolates initially produced white fluffy aerial hyphae and turned dark grayish with bright orange conidial masses. Ascomata 109.2 to 252.6 × 97.1 to...

Metabolomics fingerprint of coffee species determined by untargeted-profiling study using LC-HRMS

Coffee bean extracts are consumed all over the world as beverage and there is a growing interest in coffee leaf extracts as food supplements. The wild diversity in Coffea (Rubiaceae) genus is large and could offer new opportunities and challenges. In the present work, a metabolomics approach was implemented to examine leaf chemical composition of 9 Coffea species grown in the same environmental conditions. Leaves were analyzed by LC-HRMS and a comprehensive statistical workflow was designed. It served for univariate hypothesis testing and multivariate modeling by PCA and partial PLS-DA on the Workflow4Metabolomics infrastructure. The first two axes of PCA and PLS-DA describes more than 40% of variances with good values of explained variances. This strategy permitted to investigate the metabolomics data and their relation with botanic and genetic informations. Finally, the identification of several key metabolites for the discrimination between species was further characterized.

Formation kinetics of furfuryl alcohol in a coffee model system

The production of furfuryl alcohol from green coffee during roasting and the effect of multiple parameters on its formation were studied employing HPLC-DAD. Results show that coffee produces furfuryl alcohol in larger quantities (418µg/g) compared to other beans or seeds (up to 132µg/g) roasted under the same conditions. The kinetics of furfuryl alcohol production resemble those of other process contaminants (e.g., HMF, acrylamide) produced in coffee roasting, with temperature and time of roasting playing significant roles in quantities formed. Different coffee species yielded different amounts of furfuryl alcohol. The data point out that the amounts of furfuryl alcohol found in roasted coffee do not reflect the total amounts produced during roasting because great amounts of furfuryl alcohol (up to 57%) are evaporating and released to the atmosphere during roasting. Finally the effect of the moisture content on furfuryl alcohol formation was found to be of little impact.

Determination of selenium in roasted beans coffee samples consumed in Algeria by radiochemical neutron activation analysis method

Abstract The essential trace element selenium is a focus of attention due to its effects on human health, there being consequences of both its deficiency and excess. Due to the ultra-trace content of selenium, the neutron activation analysis method (NAA) is difficult to apply. We therefore made use of the radiochemical neutron activation analysis (RNAA) to determine Se at low level concentrations in several consumed food items in Algeria. A radiochemical procedure based on liquid–liquid separation was established in our laboratory. In this research we focused on the determination of selenium in two species of coffee: Arabica and Robusta. The accuracy of the method was assessed by analyzing the certified reference material NIST-SRM 1573a (tomato leaves). The results obtained show a selenium variation from 0.025 to 0.052 μg/g in coffee beans and an average yield of the separation of about 85%. The results of this study were compared with those obtained with samples from Brazilian, Caribbean, Indian and Kenyan coffee beans.

Volatile compounds profiles in unroasted Coffea arabica and Coffea canephora beans from different countries

Abstract Aroma is the most important factor in assessing the quality of coffee. The volatile compounds profile could be very important to confirm the authenticity of Coffea arabica. The study was carried out on two species of unroasted coffee beans: Coffea arabica from Colombia and Nepal and Coffea robusta from Uganda and Vietnam. Both Coffea arabica and Coffea canephora were imported to the country of analysis approximately 5 months prior to the research. Before the analysis, the coffee beans were kept in a sealed, dark container, at 21 °C. The tests were performed using an electronic nose. Its functioning is based on gas chromatography with two columns of different polarities in parallel and with 2 ultra sensitive Flame Ionization Detectors (FID). With multivariate statistics – Principal Components Analysis – it was possible to reduce the number of links and present them in two dimensions, which allowed for the unambiguous identification and assignment of samples to a particular species of coffee. By using an electronic nose, one can distinguish and group unroasted coffee beans’ flavours depending on the country of origin and species.

Transcripts of pectin-degrading enzymes and isolation of complete cDNA sequence of a pectate lyase gene induced by coffee white stem borer (Xylotrechus quadripes) in the bark tissue of Coffea canephora (robusta coffee).

Of the two commercially cultivated coffee (Coffea) species, C. arabica (arabica) is highly susceptible and C. canephora (robusta) is highly resistant to the insect pest Xylotrechus quadripes (Coleoptera: Cerambycidae), commonly known as coffee white stem borer (CWSB). We constructed a forward-subtracted cDNA library by Suppression Subtractive Hybridization (SSH) from robusta bark tissue for profiling genes induced by CWSB infestation. Among the 265 unigenes of the SSH EST library, 7 unigenes (5 contigs and 2 singletons) matching different pectin-degrading enzymes were discovered. These ESTs matched one pectate lyase, three polygalacturonases, and one pectin acetylesterase gene. Quantitative real-time PCR (qRT-PCR) revealed that CWSB infestation strongly induces the pectate lyase gene at 72h. Complete cDNA sequence of the pectate lyase gene was obtained through 3' and 5' RACE reactions. It was a 1595bp long sequence that included full CDS and both UTRs. Against C. canephora genome sequences in Coffee Genome Hub database ( http://coffee-genome.org/ ), it had 22 matches to different pectate lyase genes mapped on 9 of the 11 pseudochromosomes, the top match being Cc07_g00190 Pectate lyase. In NCBI database, it matched pectate lyase sequences of several plants. Apart from C. canephora, the closest pectate lyase matches were from Sesamum indicum and Nicotiana tabacum. The pectinolytic enzymes discovered here are thought to play a role in the production of oligogalacturonides (OGs) which act as Damage-Associated Molecular Pattern (DAMP) signals eliciting innate immunity in plants. The pectate lyase gene, induced by CWSB infestation, along with other endogenous pectinolytic enzymes and CWSB-specific elicitors, may be involved in triggering basal defense responses to protect the CWSB-damaged tissue against pathogens, as well as to contain CWSB in robusta.

Digital Fingerprinting of Coffee Blending by Sensitive Crystallization

The authenticity and quality of productions is an area of priority interest that involves safety of consumers and potential economic damages deriving from frauds on origin, adulteration and labeling of products. Several investigation techniques are currently used to characterize food matrices from physical-chemical-biological point of view using different methods in order to limit possible adulterations. In this work, we have developed an experimental and computational framework to improve the potentialities of sensitive crystallization: an experimental technique known since 1936, but never used for quantitative assessment of food quality. As a test case, it has been applied to investigate the geographical traceability and quality of coffee samples. An extensive statistical analysis associated with a careful choice of advanced image descriptors allows gathering quantitative information about the samples, which can constitute a digital fingerprint of their composition. With this new tool we are able to distinguish with blind tests high-quality coffee brands from low-quality mixtures, different coffee species, green from toasted condition of beans and, to a lesser extent, the macro-geographical provenience. A powder X-ray diffraction analysis reinforces the results obtained by sensitive crystallization for the case where crystalline domains are present in the coffee sample.

Levels of Antioxidant Activity and Fluoride Content in Coffee Infusions of Arabica, Robusta and Green Coffee Beans in According to their Brewing Methods

Coffee is a rich source of dietary antioxidants, and this property links with the fact that coffee is one of the world’s most popular beverages. Moreover, it is a source of macro- and microelements, including fluoride. The aim of this work was to determine antioxidant activity of coffee beverages and fluoride content depending on different coffee species and conditions of brewing. Three species of coffee, arabica, robusta and green coffee beans obtained from retail stores in Szczecin (Poland) were analyzed. Five different techniques of preparing drink were used: simple infusion, french press, espresso maker, overflow espresso and Turkish coffee. Antioxidant potential of coffee beverages was investigated spectrophotometrically by DPPH method. Fluoride concentrations were measured by potentiometric method with a fluoride ion-selective electrode. Statistical analysis was performed using Stat Soft Statistica 12.5. Antioxidant activity of infusions was high (71.97–83.21% inhibition of DPPH) depending on coffee species and beverage preparing method. It has been shown that the method of brewing arabica coffee and green coffee significantly affects the antioxidant potential of infusions. The fluoride concentration in the coffee infusions changed depending, both, on the species and conditions of brewing, too (0.013–0.502 mg/L). Methods of brewing didn’t make a difference to the antioxidant potential of robusta coffee, which had also the lowest level of fluoride among studied species. Except overflow espresso, the fluoride content was the highest in beverages from green coffee. The highest fluoride content was found in Turkish coffee from green coffee beans.

Marker-assisted selection provides arabica coffee with genes from other Coffea species targeting on multiple resistance to rust and coffee berry disease

Selecting superior genotypes is facilitated by marker-assisted selection (MAS), which is particularly suitable for transferring disease resistance alleles because it nullifies environmental effects and allows selection of resistant individuals in the absence of the pathogen or race, enabling preventive breeding. Molecular markers linked to two major genes (SH3 and SH?), conferring resistance to coffee rust, and those linked to the Ck-1 gene, conferring resistance to coffee berry disease (CBD), have previously been identified. These markers were validated and used in a progeny of crosses between Indian selections with Coffea arabica cultivars. Eleven resistant individuals homozygous for SH3 were identified by MAS. Of these, seven carry SH? from Hibrido de Timor and the gene introduced from Coffea liberica (SH3). SH? was characterized as derived from Coffea canephora. Thus, it was possible to identify C. arabica genotypes carrying important genes for rust resistance introgressed from other coffee species. MAS also allowed identification of sources of CBD resistance for use in preventive breeding for resistance to this serious disease. Using two validated molecular markers, two coffee plants carrying Ck-1 were identified: the UFV 328-60 genotype (F2) was resistant and homozygous based on both molecular markers but exhibited no markers related to SH3 and SH?, and the UFV 317-12 genotype (F1) was resistant and homozygous but resistant and heterozygous based on CBD-Sat207 and CBD-Sat235, respectively. Along with possessing Ck-1, the latter carries SH?. Overall, plants carrying different genes for resistance to rust and CBD were identified. These plants are important sources for gene pyramiding in breeding programs aimed at multiple and durable resistance.