During wet processing of coffee, the ripe cherries are pulped, then fermented and dried. This study reports an experimental approach for target identification and selection of indigenous coffee ...yeasts and their potential use as starter cultures during the fermentation step of wet processing. A total of 144 yeast isolates originating from spontaneously fermenting coffee beans were identified by molecular approaches and screened for their capacity to grow under coffee-associated stress conditions. According to ITS-rRNA gene sequencing, Pichia fermentans and Pichia kluyveri were the most frequent isolates, followed by Candida Candida glabrata, quercitrusa, Saccharomyces sp., Pichia guilliermondii, Pichia caribbica and Hanseniaspora opuntiae. Nine stress-tolerant yeast strains were evaluated for their ability to produce aromatic compounds in a coffee pulp simulation medium and for their pectinolytic activity. P. fermentans YC5.2 produced the highest concentrations of flavor-active ester compounds (viz., ethyl acetate and isoamyl acetate), while Saccharomyces sp. YC9.15 was the best pectinase-producing strain. The potential impact of these selected yeast strains to promote flavor development in coffee beverages was investigated for inoculating coffee beans during wet fermentation trials at laboratory scale. Inoculation of a single culture of P. fermentans YC5.2 and co-culture of P. fermentans YC5.2 and Saccharomyces sp. YC9.15 enhanced significantly the formation of volatile aroma compounds during the fermentation process compared to un-inoculated control. The sensory analysis indicated that the flavor of coffee beverages was influenced by the starter cultures, being rated as having the higher sensory scores for fruity, buttery and fermented aroma. This demonstrates a complementary role of yeasts associated with coffee quality through the synthesis of yeast-specific volatile constituents. The yeast strains P. fermentans YC5.2 and Saccharomyces sp. YC9.15 have a great potential for use as starter cultures in wet processing of coffee and may possibly help to control and standardize the fermentation process and produce coffee beverages with novel and desirable flavor profiles.
•Yeast diversity during wet processing of coffee was analyzed.•Yeast strains were screened to produce aromatic compounds and pectinolytic enzyme.•The potential use of selected yeasts to improve coffee processing was investigated.•Starter yeasts enhanced the aroma compound formation in the fermentation process.•Coffee beverage flavor was influenced by selected yeast starter cultures.
Although postharvest coffee fruit fermentation can improve coffee flavour and quality, the mycotoxin ochratoxin A (OTA) can also be a result of microbiological activity, albeit in the later drying ...step of coffee processing. To evaluate the possible occurrence of OTA contamination in postharvest fruit fermentation, fourteen coffees that entailed two different postharvest fruit fermentation times were evaluated. These coffees originated in the surroundings of the village of Pedra Menina in the qualified Denomination of Origin and coffee producer region of Caparaó on the border between Minas Gerais and Espírito Santo states in Brazil. All coffees were classified according to the Specialty Coffee Association (SCA) protocol and 12 achieved specialty level. OTA was determined in all 14 coffees using immunoaffinity for sample clean-up and high-performance liquid chromatography with fluorescence detection for quantification. One sample presented an OTA concentration of 0.75 µg kg
−1
and two samples showed OTA concentrations of 0.87 µg kg
−1
. The other samples had concentrations of OTA below the limit of quantification obtained in this work (0.64 µg kg
−1
). Thus, all samples showed OTA concentrations far below the most stringent maximum residue limit (MRL) of 5 µg kg
−1
established for roasted coffees by European legislation. These low levels were similar to most of the previous results for Brazilian coffees listed and tabled in this work. This comparison showed that OTA contamination due to this kind of postharvest process - fruit fermentation - should not be a concern for producers and consumers of these fermented coffees.
The aim of this study was to detect and identify the volatile compounds in coffee that was obtained in defect roast processes versus standard roasting and to determine the type and strength of the ...correlations between the roast defects and the volatile compound profile in roasted coffee beans. In order to achieve this goal, the process of coffee bean roasting was set to produce an underdeveloped coffee defect, an overdeveloped coffee defect, and defectless coffee. The "Typica" variety of Arabica coffee beans was used in this study. The study material originated from a plantation that is located at an altitude of 1400-2000 m a.s.l. in Huehuetenango Department, Guatemala. The analyses were carried out with the use of gas chromatography/mass spectrometry (GC-MS) and an electronic nose. This study revealed a correlation between the identified groups of volatile compounds and the following coffee roasting parameters: the time to the first crack, the drying time, and the mean temperatures of the coffee beans and the heating air. The electronic nose helped to identify the roast defects.
Coffee is a beverage consumed globally. Although few studies have indicated adverse effects, it is typically a beneficial health-promoting agent in a range of diseases, including depression, ...diabetes, cardiovascular disease, and obesity. Coffee is rich in caffeine, antioxidants, and phenolic compounds, which can modulate the composition of the gut microbiota and mitigate both inflammation and oxidative stress, common features of the burden of lifestyle diseases. This review will discuss the possible benefits of coffee on complications present in patients with diabetes, cardiovascular disease and chronic kidney disease, outwith the social and emotional benefits attributed to caffeine consumption.
Research has demonstrated that intraspecific functional trait variation underpins plant responses to environmental variability. However, few studies have evaluated how trait variation shifts in ...response to plant pathogens, even though pathogens are a major driver of plant demography and diversity, and despite evidence of plants expressing distinct strategies in response to pathogen pressures. Understanding trait-pathogen relationships can provide a more realistic understanding of global patterns of functional trait variation. We examined leaf intraspecific trait variability (ITV) in response to foliar disease severity, using Coffea arabica cv. Caturra as a model species. We quantified coffee leaf rust (CLR) severity-a fungal disease prominent in coffee systems-and measured key coffee leaf functional traits under contrasting, but widespread, management conditions in an agroforestry system. We found that coffee plants express significant ITV, which is largely related to shade tree treatment and leaf position within coffee canopy strata. Yet within a single plant canopy stratum, CLR severity increased with increasing resource conserving trait values. However, coffee leaves with visible signs of disease expressed overall greater resource acquiring trait values, as compared to plants without visible signs of disease. We provide among the first evidence that leaf traits are correlated with foliar disease severity in coffee, and that functional trait relationships and syndromes shift in response to increased disease prevalence in this plant-pathogen system. In doing so, we address a vital gap in our understanding of global patterns of functional trait variation and highlight the need to further explore the potential role of pathogens within established global trait relationships and spectra.
Adsorption of Ni(II) on low cost activated carbon (AC) from spent coffee (SAC) and coffee husk (HAC) has been studied. Porous textures of adsorbents were characterized by N2 and CO2 sorption ...measurements. Batch adsorption experiments were performed as a function of adsorbent dose, Ni(II)-concentration and pH. Adsorption of Ni(II) was evaluated using different adsorption isotherm models (Langmuir, Freundlich, Monolayer Model for Single-Compound Adsorption and Dubinin – Radushkevich) and thermodynamics and kinetics parameters were determined. Both adsorbents show high affinity for Ni(II), however both the surface area and the pore size of the ACs do not seem to be the determining factor in the adsorption process. These ACs are microporous in nature. In contrast, the higher oxygen amount associated to the mineral matter as K2O and carbon functionalities corresponding with OH in HAC are determining for the Ni-ion adsorption process and multi-ion anchorage mechanism. In addition, the exchange of potassium present in the ACs improves the Ni(II) adsorption process. Thermodynamics and kinetics evidence a fast and endothermic adsorption process. The maximum adsorption capacity using the Langmuir isotherm model was found to be 57.14 mg/g and 51.91 mg/g for HAC and SAC, respectively. The sorption efficiency was higher for HAC as adsorbent. At low concentrations of Ni(II) (30 mg/L) and higher temperatures (308–328 K), removals >94% were measured for HAC, achieving safe discharge concentration values.
Spent coffee ground (SCG) oil is an ideal substrate for the biosynthesis of polyhydroxyalkanoates (PHAs) by
Cupriavidus necator
. The immiscibility of lipids with water limits their bioavailability, ...but this can be resolved by saponifying the oil with potassium hydroxide to form water-soluble fatty acid potassium salts and glycerol. Total saponification was achieved with 0.5 mol/L of KOH at 50 °C for 90 min. The relationship between the initial carbon substrate concentration (
C
0
) and the specific growth rate (
µ
) of
C. necator
DSM 545 was evaluated in shake flask cultivations; crude and saponified SCG oils were supplied at matching initial carbon concentrations (
C
0
= 2.9–23.0 g/L). The Han-Levenspiel model provided the closest fit to the experimental data and accurately described complete growth inhibition at 32.9 g/L (
C
0
= 19.1 g/L) saponified SCG oil. Peak
µ
-values of 0.139 h
−1
and 0.145 h
−1
were obtained with 11.99 g/L crude and 17.40 g/L saponified SCG oil, respectively. Further improvement to biomass production was achieved by mixing the crude and saponified substrates together in a carbon ratio of 75:25% (w/w), respectively. In bioreactors,
C. necator
initially grew faster on the mixed substrates (
µ
= 0.35 h
−1
) than on the crude SCG oil (
µ
= 0.23 h
−1
). After harvesting, cells grown on crude SCG oil obtained a total biomass concentration of 7.8 g/L and contained 77.8% (w/w) PHA, whereas cells grown on the mixed substrates produced 8.5 g/L of total biomass and accumulated 84.4% (w/w) of PHA.
Key points
•
The bioavailability of plant oil substrates can be improved via saponification.
•
Cell growth and inhibition were accurately described by the Han-Levenpsiel model.
•
Mixing crude and saponified oils enable variation of free fatty acid content.
► Chlorogenic acids contents were evaluated in Coffea arabica cultivars from various crops. ► Average chlorogenic acids contents in all cultivars and crops ranged from 6.1±0.7 to 6.6±1.1g100g−1dw. ► ...Chlorogenic acids contents did not vary significantly among cultivars but differed among crops.
The present work evaluated the chlorogenic acids (CGA) content and profile in economically important Brazilian cultivars of Coffea arabica from four to five consecutive crops. The contents of three caffeoylquinic acids (CQA), two feruloylquinic acids (FQA) and three dicaffeoylquinic acids (diCQA) were evaluated in semi-dry processed green seeds of Red Catuai, Yellow Catuai, Bourbon and Mundo Novo cultivars by HPLC and LC–MS. Average CGA contents in all cultivars and crops ranged from 6.1±0.7 to 6.6±1.1g100g−1 (dry weight). The distribution of CGA classes was similar in all evaluated cultivars and crops, being CQA the major class, followed by diCQA and FQA. Total and individual CGA content did not vary significantly among cultivars when all crops were considered, but differed among crops. Our results indicate that in order to compare the CGA composition of different cultivars for selection of a CGA-rich cultivar or for other reason one should evaluate more than three crops.
Abstract
Coffee consists of several biological active compounds, such as caffeine, diterpenes, chlorogenic acids, and melanoidins, which may affect human health. The intake of each compound depends ...on the variety of coffee species, roasting degree, type of brewing method and serving size. The bioavailability and the distribution of each compound and its metabolites also contribute to coffee mechanisms of action. The health benefits of coffee consumption regarding cardiovascular system and metabolism mostly depend on its antioxidant compounds. In contrast, diterpenes and caffeine may produce harmful effects by raising lipid fraction and affecting endothelial function, respectively. Studying the mechanism of action of coffee components may help understanding weather coffee's impact on health is beneficial or hazardous. In this article, we reviewed the available information about coffee compounds and their mechanism of action. Furthermore, benefits and risks for cardiovascular system associated with coffee consumption will be discussed.
