Functional properties of coffee and coffee by-products

Rapid assessment of bioactive phenolics and methylxanthines in spent coffee grounds by FT-NIR spectroscopy

Spent coffee grounds (SCGs) are a great source of bioactive compounds with interest to pharmaceutical and cosmetic industries. Phenolics and methylxanthines are the main health related compounds present in SCG samples. Content estimation of these compounds in SCGs is of upmost importance in what concerns their profitable use by waste recovery industries. In the present work, near-infrared spectroscopy (NIRS) was proposed as a rapid and non-destructive technique to assess the content of three main phenolics (caffeic acid, (+)-catechin and chlorogenic acid) and three methylxanthines (caffeine, theobromine and theophylline) in SCG samples obtained from different coffee brands and diverse coffee machines. The content of these compounds was determined for 61 SCG samples by HPLC coupled with diode-array detection. Partial least squares (PLS) regression based models were calibrated to correlate diffuse reflectance NIR spectra against the reference data for the six parameters obtained by HPLC. Spectral wavelength selection and number of latent variables were optimized by minimizing the cross-validation error. PLS models showed good linearity with a coefficient of determination for the prediction set (Rp(2)) of 0.95, 0.92, 0.88, 071 and 0.84 for caffeine, caffeic acid, (+)-catechin, chlorogenic acid and theophylline, respectively. The range error ratio (RER) was higher for caffeine (17.8) when compared to other compounds (12.0, 10.1, 7.6 and 9.2, respectively for caffeic acid, (+)-catechin, chlorogenic acid and theophylline). Moreover, the content of caffeine could be used to predict the antioxidant properties of SCG samples (R=0.808, n=61), despite not presenting this property itself. The results obtained confirmed that NIRS is a suitable technique to screen SCG samples unveiling those with high content of bioactive compounds, which are interesting for subsequent extraction procedures.

Comparison of antioxidant activity between green and roasted coffee beans using molecular methods

Coffee is one of the most popular and widely consumed beverages worldwide due to its pleasant taste and aroma. A number of studies have been performed to elucidate the possible beneficial effects of coffee consumption on human health and have shown that coffee exhibits potent antioxidant activity, which may be attributed mainly to its polyphenolic content. However, there is also evidence to suggest that coffee roasting (the procedure which turns green coffee beans to the dark, roasted ones from which the beverage derives) may alter the polyphenolic profile of the beans (e.g., via the Maillard reaction) and, concomitantly, their antioxidant activity. In the present study, the antioxidant activity of 13 coffee varieties was examined in both green and roasted coffee bean extracts using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-eth-ylbenzothiazoline-6-sulfonic acid) (ABTS^•+) radical scavenging assays. In addition, 5 selected varieties were also examined for their protective effects against peroxyl and hydroxyl radical-induced DNA strand cleavage. Finally, C2C12 murine myoblasts were treated with non-cytotoxic concentrations of the most potent extract in order to examine its effects on the cellular redox status by measuring the glutathione (GSH) and reactive oxygen species (ROS) levels by flow cytometry. Our results revealed that, in 8 out of the 13 coffee varieties, roasting increased free radical scavenging activity as shown by DPPH and ABTS^•+ assays. Moreover, we found that when one coffee variety was roasted for different amounts of time, the increase in the antioxidant activity depended on the roasting time. By contrast, in 5 varieties, roasting reduced the antioxidant activity. Similar differences between the roasted and green beans were also observed in the free radical-induced DNA strand cleavage assay. The observed differences in the antioxidant activity between the different coffee varieties may be attributed to their varying polyphenolic content and composition, as well as to the different molecules produced during roasting. In addition, in the cell culture assay, the tested coffee extract led to increased GSH levels in a dose-dependent manner, indicating the enhancement of cellular antioxidant mechanisms.

Spent coffee ground extract suppresses ultraviolet B-induced photoaging in hairless mice

The aim of this study is to evaluate the effect of spent coffee ground (SCG) ethanol extract on UVB-induced skin aging in hairless mice. An ethanol extract of SCG (ESCG) was prepared using the residue remaining after extraction of oil from roasted SCG. High performance liquid chromatography (HPLC) analysis showed that the content of caffeine (41.58 ± 0.54 μg/mg) was higher than that of chlorogenic acid isomers (~9.17 μg/mg) in ESCG. ESCG significantly decreased the UVB-induced intracellular reactive oxygen species in HaCaT cells. UVB-induced wrinkle formation in mice dorsal skin was effectively reduced by ESCG administration; high dose of ESCG (5 g/L) caused the reduction of wrinkle area by 30% compared with UVB-treated control (UVBC). This result correlated with the ESCG-mediated decrease in epidermis thickness (25%). In addition, ESCG administration significantly reduced transdermal water loss (20%) and erythema formation (35%) derived from UVB exposure. Collagen type I (COL-1) level in dorsal skin was effectively recovered by ESCG administration. These results were supported by down-regulation of collagen-degrading matrix metalloproteinase 2 (MMP2) and 9 (MMP9) expressions. Our results indicate that ESCG protects mouse skin from UVB-induced photoaging by suppressing the expression of matrix metalloproteinases. Our study suggests that ESCG may be anti-photoaging agent.

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

Compositions of fatty acid, amino acids, and volatile compound were investigated in green coffee beans of seven cultivars of Coffearobusta grown in Hainan Province, China. The chlorogenic acids, trigonelline, caffeine, total lipid, and total protein contents as well as color parameters were measured. Chemometric techniques, principal component analysis (PCA), hierarchical cluster analysis (HCA), and analysis of one-way variance (ANOVA) were performed on the complete data set to reveal chemical differences among all cultivars and identify markers characteristic of a particular botanical origin of the coffee. The major fatty acids of coffee were linoleic acid, palmitic acid, oleic acid, and arachic acid. Leucine (0.84 g/100 g DW), lysine (0.63 g/100 g DW), and arginine (0.61 g/100 g DW) were the predominant essential amino acids (EAAs) in the coffee samples. Seventy-nine volatile compounds were identified and semi-quantified by HS-SPME/GC-MS. PCA of the complete data matrix demonstrated that there were significant differences among all cultivars, HCA supported the results of PCA and achieved a satisfactory classification performance.

Influence of coffee genotype on bioactive compounds and the in vitro capacity to scavenge reactive oxygen and nitrogen species

The influence of green coffee genotype on the bioactive compounds and the in vitro antioxidant capacity against the principal reactive oxygen (ROO(•), H2O2, HO(•), and HOCl) and nitrogen (NO(•) and ONOO(-)) species of biological relevance was investigated. This is the first report on the capacity of green coffee to scavenge H2O2, HOCl, and NO(•). Variations in the contents of total chlorogenic acids (22.9-37.9 g/100 g), cinnamoyl-amino acid conjugates (0.03-1.12 g/100 g), trigonelline (3.1-6.7 g/100 g), and caffeine (3.9-11.8 g/100 g) were found. Hydrophilic extracts of Coffea canephora and Coffea kapakata were the most potent scavengers of ROO(•), H2O2, HO(•), NO(•), and ONOO(-) due to their chlorogenic acid contents, which were, on average, 30% higher than those found in Coffea arabica and Coffea racemosa. The results showed that genotype is a determinant characteristic in the bioactive compound contents and consequently in the antioxidant capacity of green coffee.

A comprehensive review on utilization of wastewater from coffee processing

The coffee processing industry is one of the major agro-based industries contributing significantly in international and national growth. Coffee fruits are processed by two methods, wet and dry process. In wet processing, coffee fruits generate enormous quantities of high strength wastewater requiring systematic treatment prior to disposal. Different method approach is used to treat the wastewater. Many researchers have attempted to assess the efficiency of batch aeration as posttreatment of coffee processing wastewater from an upflow anaerobic hybrid reactor (UAHR)-continuous and intermittent aeration system. However, wet coffee processing requires a high degree of processing know-how and produces large amounts of effluents which have the potential to damage the environment. Characteristics of wastewater from coffee processing has a biological oxygen demand (BOD) of up to 20,000 mg/l and a chemical oxygen demand (COD) of up to 50,000 mg/l as well as the acidity of pH below 4. In this review paper, various methods are discussed to treat coffee processing wastewaters; the constitution of wastewater is presented and the technical solutions for wastewater treatment are discussed.

Coffee silverskin: a possible valuable cosmetic ingredient

CONTEXT

Currently, there is a great tendency in cosmetic area to use natural extracts. Coffee silverskin (CS) is the most abundant solid by-product generated during roasting of coffee processing.

OBJECTIVES

To evaluate different CS extracts as promising cosmetic ingredients, regarding antioxidant, antimicrobial, and cytotoxic properties.

MATERIALS AND METHODS

Aqueous, hydroalcoholic and ethanolic CS extracts were obtained by an environmentally friendly procedure considering costs and pollution. Extracts were characterized for total phenolic and flavonoid contents (TPC and TFC, respectively), antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), antimicrobial activity expressed as minimal inhibitory concentration (MIC) and cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and lactate dehydrogenase (LDH) assays in two skin cell lines (fibroblasts and keratinocytes).

RESULTS

The TPC of extracts was 18.33-35.25 mg of gallic acid equivalents per g of material on a dry basis (mg GAE/g db). The TFC of extracts was 1.08-2.47 µg cathechin equivalents per g dry material (µg CE/g db). The antioxidant activity was high, with values ranging between 95.95 and 216.40 µmol Fe(2+)/g for aqueous and alcoholic samples, respectively. Preliminary assays for antimicrobial potential showed that extracts display antibacterial activity. The MIC varied from 31.3 to 250 µg/mL for Gram-positive, and from 31.3 to 1000 µg/mL for Gram-negative. Extracts did not affect in vitro cell viability, with values near 100% in all concentrations tested.

CONCLUSION

RESULTS seem show that CS is a safe source of natural antioxidants with antifungal and antibacterial activity and no cytotoxicity, with potential usefulness for cosmetic applications.

Fungal and mycotoxin contamination of coffee beans in Benguet province, Philippines

Coffee remains an important agricultural product in Benguet province, Philippines, but is highly susceptible to fungal and mycotoxin contamination in various stages of growth and processing and in different local climates. In this study, pre- and post-harvest coffee bean samples from temperate and warm farming areas were assessed for their fungal and mycotoxin contaminants. One hundred eighty-five fungal isolates belonging to six genera were isolated representing 88.1% of mycotoxigenic fungi. The predominant species belonged to the genus Aspergillus, which are known producers of mycotoxins. Coffee beans from the post-harvest temperate group were found to have the highest percentage mycotoxigenic contamination of 98.4%, suggesting that the risk for fungal contamination is high after drying. Determination of the mycotoxins indicated 28.6% contamination. Ochratoxin A was found to be highest in dried whole cherries which contained 97.3 μg kg(-1), whilst sterigmatocystin was also highest in dried whole cherries at 193.7 μg kg(-1). These results indicate that there are risks of fungal and mycotoxin contamination of Benguet coffee at the post-harvest stage.

Coffee with ginger - interactions of biologically active phytochemicals in the model system

This study evaluated the interactions between antiradical and anti-inflammatory compounds from coffee and ginger. Results obtained for whole plant material extracts were compared with those for chlorogenic and caffeic acids (the main hydroxycinnamic acids of plant material). All the tested samples showed the ability to scavenge free radicals and to inhibit lipoxygenase (LOX) activity. Both of these activities increased after simulated gastrointestinal digestion. Aromatic additives, such as ginger, are able to change the antioxidant properties of coffee extract and antioxidant interactions may be identified using two methods. Antiradical phytochemicals from coffee and ginger acted synergistically - isoboles adopted a concave form, while after digestion in vitro an additive reaction was observed; in turn, chemical standards acted antagonistically. Water extractable LOX inhibitors acted antagonistically; however, after digestion in vitro synergism was observed. The same kind of interaction was determined for standard compounds. These results were confirmed by IF (interaction factor) analysis.

Transfer of ochratoxin A into tea and coffee beverages

Ochratoxin A (OTA) is nephrotoxic, hepatotoxic, immunotoxic, neurotoxic, reprotoxic, teratogenic, and carcinogenic (group 2B), being characterized by species and sex differences in sensitivity. Despite the fact that OTA is in some aspects a controversial topic, OTA is the most powerful renal carcinogen. The aim of this study was to make a small survey concerning OTA content in black tea, fruit tea, and ground roasted coffee, and to assess OTA transfer into beverages. OTA content was measured using a validated and accredited HPLC-FLD method with a limit of quantification (LOQ) of 0.35 ng/g. The OTA amount ranged from LOQ up to 250 ng/g in black tea and up to 104 ng/g in fruit tea. Black tea and fruit tea, naturally contaminated, were used to prepare tea infusions. The transfer from black tea to the infusion was 34.8% ± 1.3% and from fruit tea 4.1% ± 0.2%. Ground roasted coffee naturally contaminated at 0.92 ng/g was used to prepare seven kinds of coffee beverages. Depending on the type of process used, OTA transfer into coffee ranged from 22.3% to 66.1%. OTA intakes from fruit and black tea or coffee represent a non-negligible human source.

The influence of roasting and additional processing on the content of bioactive components in special purpose coffees

ABSTRACT

Coffee being the beverage consumed worldwide is also a very competitive commodity. Consequently, producers seek ways of attracting consumers by proposing e.g. novel ingredient combinations usually without evaluating their health quality. In this study, variations in health-promoting determinants for five special purpose coffee brews were characterized. The major bioactive components - chlorogenic acids (CAs) - detected by HPLC-DAD-MS included caffeoyl-, feruloyl- and dicaffeoylquinic acids. Roasting declined CAs content by 50 %, while caffeine content increased by about 30 % during this process. In roasted coffee brews studied, CAs content varied from 14.1 to 26.6 mg/g; smaller variations were seen in antioxidant potential (determined by spectrophotometric and cyclic voltammetry assays). Profiles generated by HPLC with post-column on-line antioxidant detection revealed that caffeoylquinic acids were the most abundant antioxidants in samples studied. The highest antioxidative potential exhibited coffee enriched with green coffee extract confirming the soundness of such an approach to obtain healthier products.

HIGHLIGHTS

• Special purpose coffees are equivalent to regular ones as regards antioxidant potential. • Caffeoylquinic acids are the most abundant antioxidants in coffee samples studied. • Roasting process causes some degradation of chlorogenic acids but not caffeine. • Special purpose coffees retain health benefits while being more attractive to consumers.

Coffee silverskin: characterization, possible uses, and safety aspects

The reuse of coffee silverskin (CS), the main waste product of the coffee-roasting industry, could be an alternative to its environmental disposal. However, CS could also contain undesirable compounds, such as ochratoxin A (OTA) and phytosterol oxidation products (POPs). A study on the composition of CS (caffeine, moisture, dietary fibers, carbohydrates, and polyphenol contents) was carried out, with emphasis on OTA and POPs for safety reasons. The lipid fraction showed significant amounts of linoleic acid and phytosterols (7.0 and 12.1% of lipid fraction). Noticeable levels of POPs (114.11 mg/100 g CS) were found, and the phytosterol oxidation rate varied from 27.6 to 48.1%. The OTA content was 18.7-34.4 μg/kg CS, which is about 3 times higher than the European Commission limits for coffee products. The results suggest that CS could be used as a source of cellulose and/or bioactive compounds; however, the contents of POPs and OTA might represent a risk for human safety if intended for human or livestock use.

Soluble and bound hydroxycinnamates in coffee pulp (Coffea arabica) from seven cultivars at three ripening stages

The contents of soluble and bound hydroxycinnamates (HCAs) were analyzed in coffee pulp (CP) of seven cultivars of Coffea arabica at three different ripening stages. Methodologies for the extraction and analysis of HCAs were evaluated and improved. HCAs were present mainly in the soluble fraction (68-97%). Chlorogenic acid was the main phenolic acid (94-98%) in the soluble fraction, whereas caffeic acid was the most abundant HCA found in the bound fraction (72-88%). Small amounts of free and bound ferulic and p-coumaric acids were also detected. The content of total HCAs in CP reached the maximum concentration at the semiripe stage (7.4-25.5 mg/g CP, dw) but decreased at the ripe stage for six of the seven cultivars. These findings suggest that unripe or semiripe coffee cherries, considered as defective cherries, are a potential inexpensive source of phenolic compounds, such as chlorogenic and caffeic acids.

Utilization of coffee by-products obtained from semi-washed process for production of value-added compounds

The semi-dry processing of coffee generates significant amounts of coffee pulp and wastewater. This study evaluated the production of bioethanol and volatile compounds of eight yeast strains cultivated in a mixture of these residues. Hanseniaspora uvarum UFLA CAF76 showed the best fermentation performance; hence it was selected to evaluate different culture medium compositions and inoculum size. The best results were obtained with 12% w/v of coffee pulp, 1 g/L of yeast extract and 0.3 g/L of inoculum. Using these conditions, fermentation in 1 L of medium was carried out, achieving higher ethanol yield, productivity and efficiency with values of 0.48 g/g, 0.55 g/L h and 94.11% respectively. Twenty-one volatile compounds corresponding to higher alcohols, acetates, terpenes, aldehydes and volatile acids were identified by GC-FID. Such results indicate that coffee residues show an excellent potential as substrates for production of value-added compounds. H. uvarum demonstrated high fermentative capacity using these residues.

The study of interactions between active compounds of coffee and willow (Salix sp.) bark water extract

Coffee and willow are known as valuable sources of biologically active phytochemicals such as chlorogenic acid, caffeine, and salicin. The aim of the study was to determine the interactions between the active compounds contained in water extracts from coffee and bark of willow (Salix purpurea and Salix myrsinifolia). Raw materials and their mixtures were characterized by multidirectional antioxidant activities; however, bioactive constituents interacted with each other. Synergism was observed for ability of inhibition of lipid peroxidation and reducing power, whereas compounds able to scavenge ABTS radical cation acted antagonistically. Additionally, phytochemicals from willow bark possessed hydrophilic character and thermostability which justifies their potential use as an ingredient in coffee beverages. Proposed mixtures may be used in the prophylaxis or treatment of some civilization diseases linked with oxidative stress. Most importantly, strong synergism observed for phytochemicals able to prevent lipids against oxidation may suggest protective effect for cell membrane phospholipids. Obtained results indicate that extracts from bark tested Salix genotypes as an ingredient in coffee beverages can provide health promoting benefits to the consumers; however, this issue requires further study.

Simplified sample treatment for the determination of total concentrations and chemical fractionation forms of Ca, Fe, Mg and Mn in soluble coffees

A simpler, and faster than wet digestion, sample treatment was proposed prior to determination of total concentrations for selected macro- (Ca, Mg) and microelements (Fe, Mn) in soluble coffees by flame atomic absorption spectrometry. Samples were dissolved in water and acidified with HNO3. Precision was in the range 1-4% and accuracy was better than 2.5%. The method was used in analysis of 18 soluble coffees available on the Polish market. Chemical fractionation patterns for Ca, Fe, Mg and Mn in soluble coffees, as consumed, using a two-column solid-phase extraction method, determined Ca, Mg and Mn were present predominantly as cations (80-93% of total content). This suggests these elements are likely to be highly bioaccessible.