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Coffee beverage presents unique organoleptic characteristics of aroma and taste. These sensory attributes depend on the chemical composition of the brewed coffee. Our objectives were to determine the sensory quality of the coffee beverage obtained by different brewing methods as assessed by untrained tasters and to characterize the solid residues of this extraction using the medium infrared spectrum. Four brewing methods were evaluated by 124 untrained consumers. The infusion method presented better global impression and preference of these consumers than the other brewing methods. Significant changes in the chemical composition of the coffee residues were observed. These changes influenced the acceptance of the consumers and can be due to the potential of retention or filtering of organic compounds by the brewing method. Thus, there was a sensory quality difference among the brewing methods and the infrared spectrum indicated the need to distinguish the classes of organic compounds for a better understanding of how coffee brewing interacts with the chemical composition.

The health benefits and detrimental effects of coffee consumption may be linked to chemical compounds contained in coffee beans. The aim of our study was to evaluate the concentration of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), copper (Cu), zinc (Zn), aluminum (Al), nickel (Ni), lead (Pb) and cadmium (Cd) in green and roasted samples of coffee beans purchased in Bosnia and Herzegovina, and to determine the potential health implications at current consumption level.

An electrochemical analysis using a multi-walled carbon nanotube (MWCNT) electrode is applied to examine chlorogenic acids (3-cafeoylquinic (3CQ), 4-cafeoylquinic (4CQ), 5-cafeoylquinic (5CQ), 3,4-dicafeoylquinic (34dCQ), 3,5-dicafeoylquinic (35dCQ), 4,5-dicafeoylquinic (45dCQ), 3-feruloylquinic (3FQ), 4-feruloylquinic (4FQ), and 5-feruloylquinic (5FQ) acid), which are the main ingredients of coffee polyphenols. The MWCNT electrode shows an excellent performance in the electrochemical quantification of chlorogenic acids. Cyclic voltammetry (CV) of all the chlorogenic acids shows redox peak pairs ranging between + 0.27 and + 0.31 V that are assigned to the redox reaction of the catechol group. Changes in the current due to individual chlorogenic acids at the peak potentials are proportional to their concentrations (3CQ, 4CQ, and 5CQ: linear range 0.4–194 μM, sensitivity 1.8 μA μM−1 cm−2; 34dCQ, 35dCQ, and 45dCQ: linear range 9.5–194 μM, sensitivity 4.3 μA μM−1 cm−2; and 3FQ, 4FQ, and 5FQ: linear range 5–194 μM, sensitivity 0.094 μA μM−1 cm−2). High-performance liquid chromatography (HPLC) analysis of coffee infusions shows that chlorogenic acids are almost entirely composed of 3CQ, 4CQ, and 5CQ. The total amounts of 3CQ, 4CQ, and 5CQ in coffee infusions obtained by HPLC show good agreement with those obtained by CV using the MWCNT electrode. This result indicates that the redox peak current can quantify the total amount of chlorogenic acid in a coffee infusion. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the interactions between insoluble fractions of different coffee infusions and major cocoa free antioxidants, catechin and epicatechin, as well as the interactions between different coffee infusions and dark chocolate. Espresso, filtered coffee, French press and Turkish coffee were used for this purpose. Antioxidant capacity (AC) measurements were performed by monitoring the percentage inhibition of 2,2-Diphenyl-1-picrylhydrazil (DPPH) radical. Multivariate approach was adopted for experimental design and data analysis steps. In dry basis, the AC values of infusions (mmol Trolox/kg) were ranged between 953 ± 2.6 and 1184 ± 11.3, while the AC values for their insoluble fractions were ranged between 45 ± 0.0 and 105–1.3. Interactions between the insoluble fractions of coffee infusions and catechins were synergistic for espresso and additive/antagonistic for the other infusions. Interactions between coffee infusions and chocolate were synergistic for French press and Turkish coffee and additive/antagonistic for the other infusions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The concentrations of nine essential metals (K, Mg, Ca, Na, Mn, Fe, Cu, Zn, Co) and two non-essential (Pb, Cd) metals were determined in three brands of commercially available roasted Ethiopian coffee powders (Abyssinia, Alem and Pride) obtained from local markets and their infusions using flame atomic absorption spectrometry (FAAS). An optimized digestion procedure was developed using 5 mL of HNO3 and 1 mL of HClO4 with 4 hours total time at temperature around 350 oC for digestion of 0.5 g of powder sample while 4 mL of HNO3 and 1 mL of HClO4 with 4 hours total time for 25 mL infusion evaporated to dryness. The validity of the optimized procedure was evaluated by the analysis of spiked samples whose recovery of analytes was in the range of 97−103 % for the coffee powder and 95−102 % for the infusion samples. The mean concentration of each metal in the three brands of coffee powder samples was (g element/g): K (14488467), Mg (196478), Ca (94565), Na (48412), Fe (52.04.0), Mn (23.00.9), Cu (14.00.6), Zn (15.00.8), Co (1.600.05) while that in their infusions (g element/100 mL): K (372051501), Mg (2829105), Ca (1619102), Na (59120), Fe (18.31.5), Mn (23.71.2), Cu (3.00.3), Zn (24.01.1), Co (1.80.1), respectively. The metal concentrations of the coffee powders were higher than those of coffee infusions, when expressed in the same units. The extraction was highest for K (85.6%), intermediate for Zn (57.5%), Ca (56.6%), Mg (48.0%), Na (40.7%), Co (39.8%), and Mn (33.5%) and lowest for Fe (11.6%) and Cu (6.8%). The concentrations of metals in the Ethiopian coffees were comparable to the values reported in other parts of the world.

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

A simple and fast method of the analysis of green coffee infusions was developed to measure total concentrations of Ca, Cu, Fe, Mg and Mn by high resolution-continuum source flame atomic absorption spectrometry. The precision of the method was within 1–8%, while the accuracy was within −1% to 2%. The method was used to the analysis of infusions of twelve green coffees of different geographical origin. It was found that Ca and Mg were leached the easiest, i.e., on average 75% and 70%, respectively. As compared to the mug coffee preparation, the rate of the extraction of elements was increased when infusions were prepared using dripper or Turkish coffee preparation methods. Additionally, it was established that the antioxidant activity of green coffee infusions prepared using the mug coffee preparation was high, 75% on average, and positively correlated with the total content of phenolic compounds and the concentration of Ca in the brew. [ABSTRACT FROM AUTHOR]

Highlights: [•] Simple and fast method of the analysis of coffee infusions by FAAS was developed. [•] Ca, Cu, Fe, Mg, Mn and Zn were determined in six ground coffees of the Polish market. [•] Leachability of metals depends on water used, its temperature and the brewing time. [Copyright &y& Elsevier]

The paper studies the influence of work parameters expressed as brewing time, temperature of water, particle sizes and contact time on the releasing of mineral elements (Ca, Mg, Zn, Cu, Fe and Pb) in coffee infusion. The higher extractability was obtained in the first 10 minutes for infusion made of coffee samples with particles in range of 125 µm - 500 mm and hot water for Ca (33.02 mg/100g) while in case of diffusion made of coffee beans (diameter > 2 mm) in contact with cold water no lead was noticed after 60 minutes. [ABSTRACT FROM AUTHOR]

Aqueous coffee and tea infusions were decolorized by adsorption onto activated carbon. The color of the infusions has changed gradually from brown to colorless during the decolorization process. To understand the potentiality of activated carbon, experiments were conducted to determine equilibrium time, optimum dose of adsorbent, intraparticle diffusion, adsorption isotherm, optimum pH, and desorption of color from the coffee and tea infusions. The corresponding results show that around 80-82% of color removal was achieved with 100 mg/L of activated carbon within 2 h. The isothermal equilibrium sorption data fitted well into the Langmuir isotherm. Film diffusion seems to be the rate limiting step for coffee infusions but pore diffusion for tea infusions. The sorption process appears to follow anionic type as the extent of sorption is decreasing with increasing pH. Desorption studies revealed that the sorption interaction was more of chemical nature. [ABSTRACT FROM AUTHOR]

Measurement of 40K was used for determination of potassium concentrations in leaves of agave and maguey cactus leaves, and coffee beans of various origins. The procedure was also used to study potassium transfer to tequila (alcoholic drink made of agave cactus), and the cactus and coffee infusions using 40K as a natural radioactive tracer. Counting of 40K in Marinelli containers with the aid of a low background NaI(Tl) scintillation detection system for 12–24 hours was employed. The method appeared to be simple and suitable for determination of potassium concentrations in large samples, which eliminates homogeneity problems. [ABSTRACT FROM AUTHOR]