Relationship between antioxidant capacity, chlorogenic acids and elemental composition of green coffee

The Effect of Combined Elicitation with Light and Temperature on the Chlorogenic Acid Content, Total Phenolic Content and Antioxidant Activity of Berula erecta in Tissue Culture

Chlorogenic acid is one of the most prominent bioactive phenolic acids with great pharmacological, cosmetic and nutritional value. The potential of Berula erecta in tissue culture was investigated for the production of chlorogenic acid and its elicitation combined with light of different wavelengths and low temperature. The content of chlorogenic acid in the samples was determined by HPLC-UV, while the content of total phenolic compounds and the antioxidant activity of their ethanol extracts were evaluated spectrophotometrically. The highest fresh and dry biomasses were obtained in plants grown at 23 °C. This is the first study in which chlorogenic acid has been identified and quantified in Berula erecta. The highest chlorogenic acid content was 4.049 mg/g DW. It was determined in a culture grown for 28 days after the beginning of the experiment at 12 °C and under blue light. The latter also contained the highest content of total phenolic compounds, and its extracts showed the highest antioxidant activity. Berula erecta could, potentially, be suitable for the in vitro production of chlorogenic acid, although many other studies should be conducted before implementation on an industrial scale.

Effect of processing method (natural, washed, honey, fermentation, maceration) on the availability of heavy metals in specialty coffee

The aim of this study was to determine the effect of various methods of processing, such as natural, washed, honey, anaerobic fermentation, and carbonic maceration, on the contents of heavy metals in green and roasted specialty coffees from various countries of origin (Ethiopia, Kenya, Rwanda, Burundi, Guatemala, Nicaragua, and Peru). The heavy metals aluminium (Al), nickel (Ni), chromium (Cr), cadmium (Cd), copper (Cu), and lead (Pb) were identified by a multi-element technique using inductively coupled plasma mass spectrometry. Mercury (Hg) content was determined by atomic absorption spectrometry. The processing method affected the contents of Hg, Al, Ni, Cr, Cd, and Pb in the green and roasted coffees (p < 0.001). Hg content varied in the green coffees processed by fermentation methods vs natural or washed methods (i.e. Rwandan and Guatemalan coffees). Cd content was highest in Guatemalan green coffee processed using carbonic maceration (0.062 mg/kg). Pb content differed between the Ethiopian and Rwandan roasted coffees, with the highest content in the washed method (0.252 mg/kg). The correlations between the contents of Cu and Al, Ni and Cr, and Pb and Cr were significant for both the roasted and green beans. In conclusion, the method of processing can affect the contents of heavy metals in green and roasted specialty coffees. Monitoring heavy metals when processing coffee with new methods, even though further processing such as roasting can substantially reduce their content in some cases, is therefore important.

Variables Affecting the Extraction of Antioxidants in Cold and Hot Brew Coffee: A Review

Coffee beans are a readily available, abundant source of antioxidants used worldwide. With the increasing interest in and consumption of coffee beverages globally, research into the production, preparation, and chemical profile of coffee has also increased in recent years. A wide range of variables such as roasting temperature, coffee grind size, brewing temperature, and brewing duration can have a significant impact on the extractable antioxidant content of coffee products. While there is no single standard method for measuring all of the antioxidants found in coffee, multiple methods which introduce the coffee product to a target molecule or reagent can be used to deduce the overall radical scavenging capacity. In this article, we profile the effect that many of these variables have on the quantifiable concentration of antioxidants found in both cold and hot brew coffee samples. Most protocols for cold brew coffee involve an immersion or steeping method where the coffee grounds are in contact with water at or below room temperature for several hours. Generally, a higher brewing temperature or longer brewing time yielded greater antioxidant activity. Most studies also found that a lower degree of coffee bean roast yielded greater antioxidant activity.

The Bioactive Substances in Spent Black Tea and Arabic Coffee Could Improve the Nutritional Value and Extend the Shelf Life of Sponge Cake after Fortification

The study aimed to evaluate the potential use of spent coffee powder (SCP) and spent tea powder (STP) as bioactive supplements for sponge cake. To achieve this aim, we initially compared the chemical properties of spent tea and coffee powders with those of their raw forms. Subsequently, three supplemented cake blends were prepared (1, 2, and 3% of SCP and STP) to test the effect of their addition on the chemophysical characteristics, sensory attributes, and shelf life of the final products. Our results indicated that spent tea and coffee are prospective materials for polyphenols. Spent tea powder could retain up to 72% (theaflavin trigallate), while spent coffee powder could retain up to 63.9% (1-caffeoylquinic acid) of the identified compounds compared to the raw materials. Furthermore, spent tea and coffee powders contained high levels of dietary fiber (18.95 and 31.65 g/100 g dry weight) and the elements potassium (254.6 and 1218.2 mg/100 g of DW), phosphorus (189.8 and 161.3 mg/100 g of DW), calcium (904.1 and 237.8 mg/100 g of DW), and magnesium (158.8 and 199.6 mg/100 g of DW). In addition, the fortified samples with SCP and STP significantly enhanced the nutritional values while retaining good sensory qualities compared to those of the control sample. Moreover, cakes fortified with the highest concentrations of SCP and STP (3%) showed a significant decrease in malondialdehyde content (MDA; 17.7 and 18.0 μg/g) and microbiological counts (2.4 and 2.5 log cfu/g) compared to the control cake after 14 days of storage. These findings suggest that incorporating SCP and STP into cakes not only enhances their nutritional value but also extends their shelf life. By utilizing these waste products, we can contribute to a more sustainable and ecofriendly food industry.

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.

Quality Evaluation of Hainan Robusta Coffee Bean Oil Produced by Ultrasound Coupled with Coconut Oil Extraction

This study investigates the treatment of coconut oil using thermosonic treatment in combination with green coffee beans. Under a defined ratio of coconut oil to green coffee beans, the effect of different thermosonic time on the quality parameters, active substance content, antioxidant capacity, and thermal oxidative stability of coconut oil were investigated as a strategy to potentially improve the quality of oil. Results showed that the β-sitosterol content of CCO (coconut coffee oil) treated with the thermal method combined with green coffee bean treatment reached up to 393.80 ± 11.13 mg/kg without affecting the lipid structure. In addition, DPPH clearance equivalents increased from 5.31 ± 1.30 mg EGCG/g to 71.34 ± 0.98 mg EGCG/g, and the ABTS clearance equivalent was 45.38 ± 0.87 mg EGCG/g versus 0 for the untreated sample. The improvement in thermal oxidation stability of treated coconut oil is also significant. The TG (Thermogravimetry) onset temperature was elevated from 277.97 °C to 335.08 °C and the induction time was elevated up to 24.73 ± 0.41 h from 5.17 ± 0.21 h. Thermosonic treatment in combination with green coffee beans is an ideal option to improve the quality of coconut oil. The results of this article provide new ideas for the development of plant-blended oil products and the new utilization of coconut oil and coffee beans.

Comprehensive Analysis of Metabolites in Brews Prepared from Naturally and Technologically Treated Coffee Beans

Coffee is one of the most popular beverages in the world. Therefore, this study analyzed 49 coffee samples of Arabica and Robusta species of different geographical origins and the treatment of beans including three degrees of roasting with the use of LC-MS/MS. This is the first study to present a comprehensive analysis of Kopi Luwak coffee brew metabolites in comparison to fully washed coffees and the drying post-harvest treatment of Arabica or Robusta coffee brews. Kopi Luwak showed higher levels of caffeine and theophylline in comparison to the analyzed washed and unwashed Arabica coffees, as well as a different proportion of caffeoylquinic isomers. There was no difference between Kopi Luwak and other Arabica coffees in terms of the concentration of vitamin B₃, amines, and phenolic acids. This was confirmed in PCA. The steaming and roasting of beans as well as the addition of black beans influence the concentration of 4-CQA and the nicotinic, ferulic, and quinic acids content.

Hand-Portable Miniaturized Liquid Chromatography for the Determination of Chlorogenic Acids in Dietary Supplements

With the explosive growth of the dietary supplements industry, new demands have emerged that cannot be faced with the sophisticated instrumentation available in well-equipped laboratories. In particular, there is a demand for simplified and easy-to-use instruments, capable of providing results in short times of analysis. In this study, a hand-portable miniaturized liquid chromatograph (portable LC) has been tested for the determination of chlorogenic acids (CGAs) in products intended to supplement the diet and elaborated with green coffee extracts. CGAs offer several health benefits due to their antioxidant properties, and an increasing number of dietary supplements are marketed with claimed high contents of these compounds. The results obtained with the proposed portable LC approach have been compared with those obtained with two other miniaturized benchtop liquid chromatography instruments, namely, a capillary liquid chromatograph (capLC) and a nano liquid chromatograph (nanoLC). Although compared with the methods that used the benchtop instruments, the sensitivity attainable was lower, the portable LC instrument provided a comparable analytical performance for the quantification of the main GCAs at low mg g^-1 levels, and it was clearly superior in terms of speed. The proposed portable LC-based method can be applied to assess the content and distribution profile of the predominant CGAs in this kind of dietary supplement. It can be also used to estimate the antioxidant power due to CGAs, as well as their preservation state.

The concentration of potentially toxic elements (PTEs) in the coffee products: a systematic review and meta-analysis

Coffee is one of the most consumed products globally, and its contamination with potentially toxic elements (PTEs) occurs throughout the production chain and production. Therefore, the current meta-analysis study aimed to estimate the concentration of essential elements (Cu and Co) and the contamination of PTEs (Ni, Cr, Pb, As, and Cd) in coffee. The recommended databases, including PubMed, Scopus, and ScienceDirect, were investigated to collect data regarding the contamination of PTEs in coffee products from 2010 to 2021. Among 644 retrieved citations in the identification step, 34 articles were included in the meta-analysis. The pooled mean concentration of essential elements in coffee products is much higher than that of toxic elements (Co (447.106 µg/kg, 95% CI: 445.695-448.518 µg/kg) > Ni (324.175 µg/kg, 95% CI: 322.072-326.278 µg/kg) > Cu (136.171 µg/kg, 95% CI: 134.840-137.503 µg/kg) > Cr (106.865 µg/kg, 95% CI: 105.309-108.421 µg/kg) > Pb (21.027 µg/kg, 95% CI: 20.824-21.231 µg/kg) > As (3.158 µg/kg, 95% CI: 3.097-3.219 µg/kg) > Cd (0.308 µg/kg; 95% CI: 0.284-0.332 µg/kg)). Results showed high differences between pooled concentrations of all PTEs in coffee products of different countries.

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

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

Caffeine. A critical review of contemporary scientific literature

Caffeine is a secondary metabolite extensively studied for its stimulatory properties and presumed association with specific pathologies. This alkaloid is typically consumed through coffee, tea, and other plant products but is also an additive in many medications and confectionaries. Nonetheless, despite its worldwide consumption and acceptance, there is controversial evidence as to whether its effects on the central nervous system should be interpreted as stimulatory or as an addiction in which typical withdrawal effects are canceled out with its daily consumption. The following discussion is the product of an extensive review of current scientific literature, which aims to describe the most salient topics associated with caffeine's purpose in nature, biosynthesis, metabolism, physiological effects, toxicity, extraction, industrial use and current plant breeding approaches for the development of new caffeine deficient varieties as a more economical option to the industrially decaffeinated coffees currently available to caffeine intolerant consumers. Keywords: biosynthesis, decaffeination, extraction, metabolism, physiological effects, plant breeding.

Coffee's Phenolic Compounds. A general overview of the coffee fruit's phenolic composition

Phenolic compounds are secondary metabolites ubiquitously distributed in the plant kingdom which come in a wide array of molecular configurations which confer them a comprehensive set of chemical attributes such as, but not limited to: nutraceutical properties, industrial applications (e.g., dyes, rawhide processing, beer production, antioxidants), and plant self-defense mechanisms against natural enemies also known as the Systemic Acquired Resistance (SAR).However, despite the fact, that there is a large number of phenolic-containing food products (e.g., chocolate, green tea, wines, beer, wood barrel-aged spirits, cherries, grapes, apples, peaches, plums, pears, etc.), coffee remains, in the western hemisphere, as the main source of dietary phenolic compounds reflected by the fact that, in the international market, coffee occupies the second trading position after oil and its derivatives. The following discussion is the product of an extensive review of scientific literature that aims to describe essential topics related to coffee phenolic compounds, especially chlorogenic acids, their purpose in nature, biosynthesis, determination, metabolism, chemical properties, and their effect on cup quality. Keywords: phenolic acids, caffeoylquinic acid, antioxidant capacity, metabolism, biosynthesis.

Coffee’s Melanoidins. A critical review of contemporary scientific literature

Melanoidins are brown pigments thermally generated during the non-enzymatic Maillard reaction and are present in a large number of baked and roasted food products (e.g., bakery products, dark beer, coffee, etc.), conferring their typical color and improving their appearance, which is usually considered, by the end-consumer, as an indicator of quality; After all, quality is in the eye of the beholder. The amount of melanoidins varies depending on the precursors’ concentration and the type of processing to which a given food product is submitted (baking time + temperature). Additionally, melanoidins have been in our diets for millennia, not only improving the organoleptic qualities of food but also exerting a great array of physiological benefits directly linked to their chemical composition, molecular conformation, and structural size. Aside from their prebiotic effects, melanoidins also display other beneficial properties, among which the most salient are their antioxidant capacity, antibacterial and chelating activities, and anticancer action. However, regardless of the plethora of in vitro experimental evidence that validates the properties mentioned above, there is still controversy about their significance for human health since many of these properties seem to be associated with high molecular weight melanoidins, which, because of their size, cannot cross the intestinal wall suggesting their action is relegated to the intestinal tract where after being fermented and fragmented are finally converted in a series of metabolic derivatives some of which manage to cross into the bloodstream while others are simply excreted through the feces. The following is a synthesis collected from the available scientific literature which aims to elucidate several aspects of melanoidins (i.e., synthesis, determination, metabolism, & biological activity) to create awareness about their importance for human health and provide information about where to find them to improve our diets. Keywords: Synthesis, fractionation, separation, antioxidant activity.

Quantification of Total Phenols and Antioxidants in Coffee Samples of Different Origins and Evaluation of the Effect of Degree of Roasting on Their Levels

Phenolic and antioxidant compounds have received considerable attention due to their beneficial effects on human health. The aim of this study is to determine the content of total phenols and antioxidants in fifty-two coffee samples of different origins, purchased from the Jordanian local market, and investigate the effect of the degree of roasting on the levels of these compounds. The coffee samples were extracted using the hot water extraction method, while Folin−Ciocalteu (FC) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay methods were used to analyze these compounds. The results showed that the highest content of total phenol (16.55 mg/g equivalent to GAE) was found in the medium roasted coffee, and the highest content of antioxidants (1.07 mg/g equivalent to TEAC) content was found in the green coffee. Only light and medium roasted coffee showed a significant correlation (p < 0.05, R2 > 0.95) between the average of total phenolic and antioxidant content. A negative correlation between the antioxidant content and the degree of roasting (p < 0.05, R2 > 0.95) were shown, while it did not correlate with phenolic contents. Previously, a positive correlation between antioxidant and chlorogenic acids content was observed, with no correlation between the origin of coffee samples nor heavy metal content, which was previously determined for the same coffee samples. These findings suggest that the antioxidant content for coffee extracts is largely determined by its chlorogenic acid content, rather than the coffee origin or total phenolic and heavy metals content.

Characterization of bioactive, chemical, and sensory compounds from fermented coffees with different yeasts species

Selected yeasts for coffee fermentation are correlated with changes in chemical compounds and beverage sensory characteristics. This work aimed to evaluate the chemical and sensory modifications of coffee fermented with one yeast (Saccharomyces cerevisiae CCMA 0543, Candida parapsilosis CCMA 0544, or Torulaspora delbrueckii CCMA 0684) and in co-inoculation (from two to two and the three together) by dry processing. Real-time PCR analyzes, total phenolic content and antioxidant activity (DPPH, ABTS, and FRAP), liquid and gas chromatography, and sensory analysis were performed. Caparaó coffees showed a higher C. parapsilosis (6.14 Log cell.g^-1) population followed by S. cerevisiae (5.85 Log cell.g^-1) and T. delbrueckii (4.64 Log cell.g^-1). The total phenolic content has a strong and positive correlation with the fermentation time and the roasted beans and a moderate and positive correlation with DPPH, FRAP, and ABTS. Coffee inoculated with T. delbrueckii reduced caffeine concentration during the fermentation process. In co-cultivation, the trigonelline concentration showed the most significant decrease (around 4 mg.g^-1) when inoculated with S. cerevisiae and T. delbrueckii. Detection of some organic acids and volatile compounds during fermentation may indicate that the starter cultures used different metabolic routes. All co-inoculation treatments presented the best sensory scores (>86 points). In the inoculated fermentation, fruity, citric, molasses, freshness, and wine notes appeared. The co-inoculated treatment with S. cerevisiae CCMA 0543, C. parapsilosis CCMA 0544, and T. delbrueckii CCMA 0684 was the best, considering the diversity of sensory notes descriptors and the final concentration of organic acids.

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.

Supercritical CO2-ethanol extraction of oil from green coffee beans: optimization conditions and bioactive compound identification

In this research, a supercritical CO₂-ethanol extraction was optimized to obtain a green coffee oil rich in bioactive compounds. A face-centered central composite design was used to evaluate the effect of temperature (50-70 °C), extraction pressure (15.0-30.0 MPa), and cosolvent content (5-20%) on the extraction yield and total phenolic compound content of green coffee supercritical extract (GCSE). The experimental data were fitted to a second-order polynomial model. According to the statistical analyses, the lack of fit was not significant for either mathematical model. From the response surface plots, the extraction pressure and cosolvent content significantly impacted the extraction yield, while the total phenolic compound content was impacted by temperature and cosolvent content. The optimal conditions were a 20% cosolvent content, a pressure of 30 MPa, and a temperature of 62 °C, which predicted an extraction yield of 7.7% with a total phenol content of 5.4 mg gallic acid equivalent g GCSE^-1. The bioactive compounds included 5-caffeoylquinic acid (11.53-17.91 mg g GCSE^-1), caffeine (44.76-79.51 mg g GCSE^-1), linoleic acid (41.47-41.58%), and palmitic acid (36.07-36.18%). Our results showed that GCSE has the outstanding chemical quality and antioxidant potential, suggesting that GCSE can be used as a functional ingredient.

Acids in coffee: A review of sensory measurements and meta-analysis of chemical composition

Coffee contains a variety of organic acids (OAs) and chlorogenic acids (CGAs) that contribute to overall sensory properties. Large variations in preparation and measurement methodology across the literature complicate interpretation of general trends. Here, we perform a systematic review and meta-analysis of the published literature to elucidate the concentrations of OAs and CGAs in both Coffea arabica (arabica) and Coffea canephora (robusta), for both green coffee and roasted coffee at multiple roast levels. A total of 129 publications were found to report acid concentration measurements, yielding 8,634 distinct data points. Analysis of the full data set reveals several trends. First, roasted robusta has considerably more acidic compounds than arabica with 2 to 5 times as much total OAs, and much larger amounts of formic and acetic acid. As for CGAs, in both arabica and robusta 5-CQA is the major component, and progressive roasting decreases the concentration of all CGAs. The total amount of CGA present was more dependent on roast level than the type of coffee (arabica vs. robusta). Overall, this meta-analysis suggests that the increases in certain OAs with roast level might play more of a role in the sensory profile of dark roast coffees than previously suspected.

Green coffee VS dietary supplements: A comparative analysis of bioactive compounds and antioxidant activity

The aim of this work was to assess and compare both the antioxidant potential and content of the selected biologically active substances in green coffee samples and dietary supplements based on green coffee extracts. The newly developed method using HPLC coupled with Corona detector (HPLC-CAD) allowed the analysis of chlorogenic acid, caffeine, caffeic acid, coumaric acid, and ferulic acid in a single run. The method was validated and characterized by a wide concentration range (5-75 μg/mL), sensitivity, accuracy (92.7-112%), repeatability (RSD <5.32%), and precision (1.80-4.04%). The assessment of antioxidant potential was done by the spectrophotometric Folin-Ciocalteu method. Green coffee samples and extract characterized by comparable or, in the case of some samples, even higher antioxidant properties than dietary supplements. There was found a great variety of CGA levels in dietary supplements (0.33-329 mg/g) compared to the green coffee samples (32.7 mg/g - 47.6 mg/g). The highest caffeine content (156 mg/tablet) was determined in one dietary supplement, while green coffee samples contained its lower levels (20.9 mg/g). The quality of some supplements is not satisfactory as their composition does not comply with the manufacturer's declaration. There were found discrepancies between the value determined and declared by the producer (<243%).

Coffee Brews: Are They a Source of Macroelements in Human Nutrition?

Coffee brews, made by pouring water on coffee grounds or brewing in an espresso machine, are among the most popular beverages. The aim of this study was to summarize data on the content of macroelements (sodium, potassium, calcium, magnesium, and phosphorus) in coffee brews prepared with different methods, as well as to review the factors influencing the content of the elements. Studies from 2000 to 2020, published in the PubMed and Google Scholar databases, were reviewed. Taking into account the results presented by the authors, we calculated that one portion of coffee brew can cover 7.5% or 6.4% (for women and men) and 6.6% of the daily requirement for magnesium and potassium, respectively. Coffee provides slightly lower amounts of phosphorus (up to 2.2%), sodium (up to 2.2%), and calcium (up to 0.7% of the daily requirement for women and 0.6% for men). If coffee is drunk in the quantity of three to four cups, it can be an important source of magnesium, considering the risk of magnesium deficiency in modern societies.

Heavy-Metal Contents and the Impact of Roasting on Polyphenols, Caffeine, and Acrylamide in Specialty Coffee Beans

The aim of this study was to determine the effect of roasting on the contents of polyphenols (PPH), acrylamide (AA), and caffeine (CAF) and to analyze heavy metals in specialty coffee beans from Colombia (COL) and Nicaragua (NIC). Samples of NIC were naturally processed and COL was fermented anaerobically. Green beans from COL (COL-GR) and NIC (NIC-GR) were roasted at two levels, light roasting (COL-LIGHT and NIC-LIGHT) and darker roasting (COL-DARK and NIC-DARK), at final temperatures of 210 °C (10 min) and 215 °C (12 min), respectively. Quantitative analyses of PPH identified caffeoylquinic acids (CQA), feruloylquinic acids, and dicaffeoylquinic acids. Isomer 5-CQA was present at the highest levels and reached 60.8 and 57.7% in COL-GR and NIC-GR, 23.4 and 29.3% in COL-LIGHT and NIC-LIGHT, and 18 and 24.2% in COL-DARK and NIC-DARK, respectively, of the total PPH. The total PPH contents were highest in COL-GR (59.76 mg/g dry matter, DM). Roasting affected the contents of PPH, CAF, and AA (p < 0.001, p < 0.011 and p < 0.001, respectively). Nickel and cadmium contents were significantly higher in the COL-GR than in the NIC-GR beans. Darker roasting decreased AA content, but light roasting maintained similar amounts of CAF and total PPH.

On the soil-bean-cup relationships in Coffea arabica L

BACKGROUND

The relationships between soil and coffee beans variables were evaluated and then the influence of bean composition on cup quality attributes was computed by means of relation studies. A total of 139 coffee and soil samples were collected directly from the same number of coffee plantations in Chiapas, Mexico.

RESULTS

In the elemental composition, only phosphorus, potassium, calcium, and copper in coffee beans had a significant (P < 0.05) relationship with the content of the same elements in soil. The level of macro- and microelements in the coffee bean affected some of the cup quality attributes, but variables such as texture, titratable acidity, and pH of water in soil had a major influence on those attributes. Caffeine, trigonelline, and 5-caffeoylquinic acid in green coffee beans also had a significant influence (P < 0.05) on the sensory attributes of the beverage.

CONCLUSION

The elemental composition of soil and coffee beans was important in explaining the cup quality attributes, but the most important variables influencing the sensory quality of coffee were altitude of plantations and moisture of coffee beans. © 2020 Society of Chemical Industry.

Arabica and Conilon coffee flowers: Bioactive compounds and antioxidant capacity under different processes

This study presents innovative research for comparison of the effect of the different dehydration techniques and methods of extraction on the antioxidant potential and bioactive compounds of Conilon and Arabica coffee flowers. The compounds were analyzed by high performance liquid chromatography and the antioxidant capacity evaluated by the 2,2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide assays. Among the compounds evaluated, trigonelline, gallic acid, chlorogenic acid, and caffeine were identified, with trigonelline and caffeine being those with the highest concentration. The investigated factors significantly influenced the profile of the bioactive compounds identified, and the antioxidant capacity. The 92 °C infusion of freeze-dried Conilon coffee flowers, in general, showed greater antioxidant capacity by ABTS and DPPH assays, as well as total phenolic content. Lyophilization had a positive influence on maintaining the content of phenolic compounds and antioxidant capacity of the samples. Coffee flowers proved to be a potential raw material for making tea-like drinks.

Determination of selenium species in beetroot juices

Over the past years, there is an increasing demand for healthy, natural foods. Due to the high content of betalains, beetroots are widely used in the food industry as a natural colorant. In this study, beetroot juices are shown as a great source of selenium compounds. The juices were purchased from a local store and the ecological one was purchased form organic street market. The content of organic selenium species, as well as betalains, were evaluated using hydrophilic interaction liquid chromatography (HILIC) chromatography. The concentrations of selenomethionine (SeMet) and methylselenocysteine (MeSeCys) in analyzed juices were comparable except for juice from ecological cultivation. In that case, the concentration of SeMet is the highest of all studied juices, but simultaneously the concentration of MeSeCys was the lowest one. No traces of major inorganic species of Se, such as Se(IV) and Se(VI) was detected. The reducing power of juices evaluated by Folin-Ciocalteu assay was in range 50.78-166.7 mg GA/L. Juices obtained from beetroot from ecological cultivation showed the highest ability to scavenge the 1,1-diphenyl-2- picrylhydrazyl (DPPH) radicals. There was a correlation between the yellow pigment content and the presence of selenocysteine in studied juices.

Optimization of the Extraction from Spent Coffee Grounds Using the Desirability Approach

The purpose of this work was the optimization of the extraction from spent coffee grounds, specifically 100% Arabica coffee blends, using a desirability approach. Spent coffees were recovered after the preparation of the espresso coffee under the typical conditions used in coffee bars with a professional machine. Spent coffee was subjected to different extraction procedures in water: by changing the extraction temperature (60, 80, or 100 °C) and the solvent extraction volume (10, 20, 30 mL for 1 g of coffee) and by maintaining constant the extraction time (30 min). The ranges of the process parameters, as well as the solvent to be used, were established by running preliminary experiments not reported here. The variables of interest for the experimental screening design were the content of caffeine, trigonelline, and nicotinic acid, quantitatively determined from regression lines of standard solutions of known concentrations by a validated HPLC-VWD method. Since solvent extraction volumes and temperatures were revealed to be the most significant process variables, for the optimization of the extraction process, an approach based on Response Surface Methodology (RSM) was considered. In particular, a Box-Wilson Central Composite Design, commonly named central composite design (CCD), was used to find the optimal conditions of the extraction process. Moreover, the desirability approach was then applied to maximize the extraction efficiency by searching the optimal values (or at least the best compromise solution) for all three response variables simultaneously. Successively, the best extract, obtained in a volume of 20 mL of water at an extraction temperature of 80 °C, was analyzed for total phenol content (TPC) through the Folin–Ciocalteu assay, and the antioxidant capacities (AC) through the trolox equivalent (TE) antioxidant capacity (DPPH), ferric-ion reducing antioxidant parameter (FRAP), and radical cation scavenging activity and reducing power (ABTS). The TPC and the AC for spent coffee were high and comparable to the results obtained in previous similar studies. Then, the extract was evaluated by inductively coupled plasma mass spectrometry (ICP–MS), revealing that potassium was the most abundant element, followed by phosphorus, magnesium, calcium, sodium, and sulfur, while very low content in heavy metals was observed. Preliminary in vitro assays in keratinocyte HaCaT cells were carried out to assess the safety, in terms of cytotoxicity of spent coffee, and results showed that cell viability depends on the extract concentration: cell viability is unmodified up to a concentration of 0.3 mg/mL, over which it becomes cytotoxic for the cells. Spent coffee extract at 0.03 and 0.3 mg/mL showed the ability to reduce intracellular reactive oxygen species formation induced by hydrogen peroxide in HaCaT cells, suggesting its antioxidant activity at intracellular levels.

Evaluation of antioxidant activity of chlorogenic acids and coffee extracts by an electrochemical DNA-based biosensor

Sensitivity of dsDNA structure towards OH radicals as the pro-oxidants has been utilized as the detection principle of an analytical procedure applied for the first time to the evaluation of antioxidant activity (AOA) of 6 chlorogenic acids (CGAs) and extracts of 10 coffees. A nanostructured electrochemical DNA-based biosensor was prepared using a commercial electrode assembly and treated in the DNA cleavage agent formed by the Fenton type reaction. An addition of CGAs and aqueous coffee extracts significantly diminishes the degree of DNA degradation determined using cyclic voltammetry (CV) with the redox indicator [Fe(CN)6]3-/4-. The AOA decreases in order caffeic acid, CFA, >caffeoylquinic acids, CQAs, >dicaffeoylquinic acids, diCQAs, exhibiting the relative portion of survived DNA of about 71%, 70% and 69%, respectively, and of about 72% for C. robusta, Cherry, India (green bean) to 49% for Nescafé Espresso. Mechanisms of antioxidative properties are discussed.

Effects of encapsulated green coffee extract and canola oil on liquid kashk quality

In this study, we used a water-in-oil (W/O) emulsion encapsulation technique to enhance green coffee extract in the novel kashk product and protect it against hot filling. Green coffee extracts (GCE) in free (1%, 0.5%, and 0.25%) and encapsulated form (EGCE) (5%, 2.5%, and 1.25%) were added to kashk during hot filling, and their physicochemical and sensory properties were investigated. The EGCE kashk had higher oxidative stability (0.43 h) than the control due to the extract’s high phenolic content and DPPH radical scavenging activity (74%). Although a high concentration of GCE caused a higher pH (4.02), the latter declined in all the samples during the storage period. Further, the size of droplets in the emulsion varied from 3.20 to 8.51 μm, confirming the well-encapsulated GCE by Fourier transform infrared. In addition, palmitic acid and oleic acid were detected in GCE by gas chromatography as the main saturated and unsaturated fatty acids, respectively. All the treatments had similar rheological properties and the highest flow index was observed in the samples with EGCE 5% on day 60. The sensory evaluation showed that the assessors preferred the kashk formulated with 1% GCE. Finally, GCE encapsulation protected the color of the samples, and the b* value remained unchanged, whereas the lightness (L*) increased. We suggest that a W/O emulsion is a successful technique for GCE encapsulation in kashk and can offer the latter to consumers as an alternative type of flavored dairy product with a better shelf life and health benefits.

Analysis of Methanolic Extracts and Crude Polysaccharides from the Leaves of Chuanminshen violaceum and Their Antioxidant Activities

The root of Chuanminshen violaceum is used as an important edible and medicinal plant in China. However, its leaves are generally considered byproducts, and therefore do not have a use. Thus, the phenolic compounds in the methanolic extracts (CVLMs) and the chemical characteristics of crude polysaccharides (CVLPs) from the leaves of C. violaceum and their in vitro antioxidant activities were explored. The results showed that chlorogenic acid and rutin were the major individual phenolic compounds in the leaves, which ranged from 1.22 ± 0.03 to 2.87 ± 0.04 mg/g DW, and from 2.25 ± 0.04 to 4.03 ± 0.05 mg/g DW, respectively. Meanwhile, the extraction yields of CVLPs from the leaves ranged from 4.73% to 5.41%. The CVLPs consisted of mannose, rhamnose, galacturonic acid, glucose, galactose, and arabinose, suggesting the existence of pectic polysaccharides. Furthermore, both CVLMs and CVLPs exhibited strong antioxidant activities. Chlorogenic acid and rutin were major contributors to the antioxidant activities of CVLMs, and the antioxidant activities of CVLPs were closely correlated to their α-1,4-D-galactosiduronic linkages. The results are beneficial for understanding the chemical properties and in vitro antioxidant activities of CVLMs and CVLPs. The leaves of C. violaceum have potential to be developed as natural antioxidants.

Antioxidant Sources from Leaves of Russian Dandelion

Taraxacum kok-saghyz (TKS) is a dandelion species native to Kazakhstan, Uzbekistan and north-west China, considered as a promising alternative source of natural rubber from its roots. The aim of this study was to investigate the possible exploitation of TKS leaves, a rubber byproduct, as a source of phenolic compounds with antioxidant properties for potential applications in forage, nutraceutical and pharmacological fields. Two accessions (TKS016, TKS018) grown under Mediterranean conditions of Sardinia were evaluated at vegetative and flowering stages. The leaves of TKS018 had the highest antioxidant capacity (19.6 mmol trolox equivalent antioxidant capacity 100 g^-1 ), total phenolic (106.4 g gallic acid equivalent kg^-1 ), tannic phenolics (58.5 g gallic acid equivalent kg^-1 ) and total flavonoid contents (22.9 g catechin equivalent kg^-1 ). At both phenological stages, TKS016 showed significantly lower values than TKS018 in 1,1-diphenyl-2-picrylhydrazyl (DPPH), total phenolic and tannic phenolics. Six individual molecules were identified, namely chlorogenic, cryptochlorogenic, caffeic, sinapic, chicoric and 3,4-dimethoxycinnamic acids. Chicoric (8.53-10.68 g kg^-1 DW) and chlorogenic acids (4.18-7.04 g kg^-1 DW) were the most abundant. TKS leaves represent a valuable source of chicoric acid with potential application as antioxidant to be used as herbal medicine and nutrition for production of healthy food/feed.

Effect of in vitro digestion-fermentation on green and roasted coffee bioactivity: The role of the gut microbiota

Coffee is one of the most consumed beverages and has been linked to health in different studies. However, green and roasted coffees have different chemical composition and therefore their health properties might differ as well. Here, we study the effect of in vitro digestion-fermentation on the antioxidant capacity, phenolic profile, production of short-chain fatty acids (SCFAs), and gut microbiota community structure of green and roasted coffee brews. Roasted coffees showed higher antioxidant capacity than green coffees, with the highest level achieved in fermented samples. Polyphenol profile was similar between green and roasted coffees in regular coffee brews and the digested fraction, but very different after fermentation. Production of SCFAs was higher after fermentation of green coffee brews. Fermentation of coffee brews by human gut microbiota led to different community structure between green and roasted coffees. All these data suggest that green and roasted coffees behave as different types of food.

Antioxidant properties of coffee substitutes rich in polyphenols and minerals

The analysis of general content of polyphenols, minerals and antioxidant activity of infusions from selected coffee substitutes is presented. The obtained results showed that the coffee infusions prepared from acorns exhibit the highest radical scavenging capacities for DPPH (EC₅₀ = 0.063-0.066 mg_d.w./mL), ABTS (EC₅₀ = 0.021-0.029 mg_d.w./mL), OH(EC₅₀ = 2.050-2.378 mg_d.w./mL) as well as the highest ability to Fe³⁺ reduction (FRAP) (∼1.1 mmolFe/g_d.w). These coffee substitutes also contain the greatest values of polyphenols (45-50 mgGA/g_d.w). Analyzed coffee substitutes differ in both quality and quantity of polyphenols, but all tested coffees contain gallic and chlorogenic acids. The most of phenolic compounds was found in herbal-cereal coffee substitute. The quantitative results and PCA analysis indicated a good correlation between the antioxidant activity and total polyphenols, flavonoids and gallic acid content. Using the obtained data on the composition and antioxidant properties of extracts the cluster analysis (CA) was performed to distinguish similar or close types of coffee.

Determination of Three Main Chlorogenic Acids in Water Extracts of Coffee Leaves by Liquid Chromatography Coupled to an Electrochemical Detector

Coffee is a beverage widely consumed in the world. The coffee species most commercialized worldwide are Arabica (Coffea arabica) and Robusta (Coffea canephora). Roasted coffee beans are the most used, but coffee leaves are also consumed as infusion in several countries for traditional medicinal purposes. They contain several interesting phenolic antioxidant compounds mainly belonging to chlorogenic acids (CGAs). In the present work, a liquid chromatography-electrochemical detection (LC-EC) method was developed for the determination of three main chlorogenic acid isomers, namely 3-, 4-, and 5-caffeoylquinic acids (CQA), in coffee leaves aqueous extracts. Samples from eight coffee species, namely; Coffea arabica, Coffea canephora, Coffea liberica, Coffea humilis, Coffea mannii, Coffea charrieriana, Coffea anthonyi, and Coffea liberica var. liberica, were grown and collected in tropical greenhouses. Linearity of the calibration graphs was observed in the range from the limit of quantification to 1.0 × 10-5 M, with R² equal to 99.9% in all cases. High sensitivity was achieved with a limit of detection of 1.0 × 10-8 M for 3-CQA and 5-CQA (i.e., 3.5 µg/L) and 2.0 × 10-8 M for 4-CQA (i.e., 7.1 µg/L). The chromatographic profile of the samples harvested for each Coffea species was studied comparatively. Obtained raw data were pretreated for baseline variations and shifts in retention times between the chromatographic profiles. Principal Component Analysis (PCA) was applied to the pretreated data. According to the results, three clusters of Coffea species were found. In the water sample extracts, 5-CQA appeared to be the major isomer, and some species contained a very low amount of CQAs. Fluctuations were observed depending on the Coffea species and harvesting period. Significant differences between January and July were noticed regarding CQAs content. The species with the best CQAs/caffeine ratio was identified. The LC-EC data were validated by liquid chromatography-high resolution mass spectrometry (LC-HRMS).

Simultaneous quantification of caffeine and chlorogenic acid in coffee green beans and varietal classification of the samples by HPLC-DAD coupled with chemometrics

A chromatographic procedure (HPLC-DAD) using a relatively rapid gradient has been combined with a chemometric curve deconvolution method, multivariate curve resolution-alternating least squares (MCR-ALS), in order to quantify caffeine and chlorogenic acid in green coffee beans. Despite that the HPLC analysis (at these specific operating conditions) presents some coeluting peaks, MCR-ALS allowed their resolution and, consequently, the creation of a calibration curve to be used for the quantification of the analytes of interest; this procedure led to a high accuracy in the quantification of caffeine and chlorogenic acid present in the samples. In a second part of this study, the possibility of classifying the green coffee beans on the basis of their cultivar (Arabica or Robusta), by partial least squares discriminant analysis (PLS-DA) and soft independent modeling of class analogies (SIMCA), has been explored. SIMCA resulted in 100% of sensitivity and specificity for the Arabica class, while for the Robusta, it reached 66.7% of sensitivity and 100% of specificity, or 100% of sensitivity and 100% of specificity, depending on the extraction procedure followed prior to the chromatographic analysis; PLS-DA achieved 100% of correct classification independently of the procedure used for the extraction.

Positive and negative aspects of green coffee consumption - antioxidant activity versus mycotoxins

BACKGROUND

The quality of coffee depends not only on the contents of healthy compounds but also on its contamination with microorganisms that can produce mycotoxins during development, harvesting, preparation, transport and storage.

RESULTS

The antioxidant activity of green coffee brews measured in this study by ABTS, DPPH and Folin-Ciocalteu assays showed that coffee extracts from Robusta beans possessed higher activity in all assays than extracts from Arabica beans. The occurrence of ochratoxin A and aflatoxins (B1, B2, G1 and G2) in green coffee beans was studied using liquid chromatography/mass spectrometry. Apart from mycotoxins, the content of ergosterol as a marker indicating fungal occurrence was also determined. Among aflatoxins, aflatoxin B1 was the dominant mycotoxin in coffee bean samples, with the highest level at 17.45 ng g^-1 . Ochratoxin A was detected in four samples at levels ranging from 1.27 to 4.34 ng g^-1 , and fungi potentially producing this toxin, namely Aspergillus oryzae, Alternaria sp., Aspergillus foetidus, Aspergillus tamarii and Penicillium citrinum, were isolated.

CONCLUSION

Steaming and decaffeination of coffee beans increased antioxidant activities of brews in comparison with those prepared from unprocessed beans. Although toxins can be quantified in green coffee beans and novel fungi were isolated, their concentrations are acceptable according to legal limits. © 2017 Society of Chemical Industry.