Dark Roast Coffee Research Articles

Assessment of the Interaction of Acetylcholinesterase Binding with Bioactive Compounds from Coffee and Coffee Fractions Digested In Vitro in the Gastrointestinal Tract.

The aim of the study was to evaluate the degree of acetylcholinesterase (AChE) inhibition by green and light- and dark-roasted coffee extracts and their fractions after digestion in a simulated gastrointestinal tract. The analysis was carried out using isothermal titration calorimetry, molecular docking, and dynamics simulations. The results showed that 3-O-caffeoylquinic acid binds strongly to AChE through hydrogen interactions with the amino acids ARG289A, HIS440A, and PHE288A and hydrophobic interactions with TYR121A in the active site of the enzyme. The Robusta green coffee extract (ΔG = -35.87 kJ/mol) and dichlorogenic acid fraction (ΔG = -19-29 kJ/mol) showed the highest affinity. Dichlorogenic acids (3,4-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid, and 3,4-O-dicaffeoylquinic acid) have high affinity for AChE as single compounds (ΔG(ITC) = -48.99-55.36 kJ/mol, ΔG(LF/AD) = -43.38-45.38 kJ/mol). The concentration necessary to reduce AChE activity by 50% amounted to 0.22 μmol/μmol chlorogenic acids to the enzyme.

Matrix-assisted laser desorption/ionization mass spectrometry for the rapid and high throughput analysis of betaine and trigonelline in Lycium chinense Mill. and trigonelline in coffee

A rapid, simple, effective, and green method for the determination of betaine and trigonelline from Lycium chinense Mill. (LCM) and the quantification of the trigonelline in coffee was proposed and validated by matrix-assisted laser desorption ionization time-of-flight mass spectrometric (MALDI-TOF MS) detection. Due to without chromatographic separation, the method greatly shortened the detection time. The detection of betaine and trigonelline concentration showed good linearity in the range of 1–100 μg/mL and 0.01–100 μg/mL, with correlation coefficients r2 = 0.9962 and 0.9946, respectively. The good reproducibility and reliability of the method were demonstrated by excellent intraday and interday precisions with RSD <8.3%, and the recovery of betaine and trigonelline ranged from 92.2% to 116.0%. Analysis of LCM and coffee extracts (raw, light-roasted, and dark-roasted coffee beans) gave results in agreement with the literature. The method appeared as a fast and reliable alternative method for routine Lycium chinense and coffee analysis.

The effect of roasting degrees on bioactive compounds levels in Coffea arabica and their associations with glycated hemoglobin levels and kidney function in diabetic rats

The current study aims to assess the content of coffee oil, diterpenes, caffeine, and chlorogenic acid in coffee beans, and to evaluate the effects of roasting degrees on bioactive compound levels in Coffea arabica and their associations with glycated hemoglobin levels and kidney function parameters in streptozotocin-induced diabetic rats. These constituents were quantified using Soxhlet, liquid–liquid extraction (LLE), and high-performance liquid chromatography (HPLC)-diode array detecto (DAD). The outcomes exhibited a positive correlation between levels of coffee oil and diterpenes with a roasting degree. However, it demonstrated a negative correlation between caffeine and chlorogenic acid with a roasting degree. The male rats were categorized into two sections: healthy (nondiabetic) and streptozotocin-induced diabetic groups. Rats have daily administrated 2 ml of coffee extract using an oral gavage subjected to different roasting degrees for 3 weeks. Fasting blood glucose (FBG), urea, and creatinine in serum were assayed at baseline and end of the experiment. The highest significant elevation (Pa = 0.016) in the mean urea and creatinine levels was noted in the diabetic group administrated with dark coffee extract whereas the lowest elevation was in the diabetic group administrated with green coffee extract. In conclusion, our study has shown that coffee roasting degree may have a potential negative effect on kidney function that may accelerate or exacerbate diabetic nephropathy in induced diabetic rats. A noteworthy change in urea levels was observed in diabetic rats treated with dark-roasted coffee, which might be attributed to the decline in antioxidant constituents: chlorogenic acids and diterpenes.

Effects of coffee with different roasting degrees on obesity and related metabolic disorders

This study aimed to assess the effect of unroasted, dark and very dark roasted coffee on obesity and metabolic disorders in obese rats. All coffee samples significantly reduced weight gain (∼17%) compared to obese control. Coffee reduced glucose levels (∼17%) upon a glucose tolerance test in all cases compared to the control, while fasting glucose only decreased (∼26%) with very dark coffee. Insulin levels and insulin resistance significantly decreased (∼77% and 65% respectively) with all coffee samples compared to the control. Unroasted and dark roasted coffee decreased triglycerides (∼21% and ∼ 11%, respectively), and unroasted coffee also reduced free fatty acids (∼43%) and adipocyte size. Coffee decreased liver steatosis (∼55%) and Caspase-3 levels (∼27%), regardless of the roasting degree. Overall, coffee plays a positive role in restraining obesity and related metabolic disorders but, depending on the metabolic pathway and relevant marker, an effect of roasting could be either found or not.

The effect of fluidized bed roaster temperature on the roasted coffee beans antioxidant activity and its sensory evaluation

A fluidized Coffee roaster has been developed. Application of the roaster on coffee beans roasting gave roasted coffee beans with characteristics of being clean and well-roasted. It also could preserve the coffee beans aroma and maintain the antioxidant activity. In this report, the effect of the roasting temperature on the antioxidant activity as well as the aroma and the taste of the roasted coffee beans was examined. The coffee beans used in this experiment were Arabica coffee originating from Tlahap, Temanggung, Indonesia. The roasting conditions were at the temperatures of 205 to 240 °C and it was performed to achieve three degrees of roasted coffee which were light roasts (205 °C), medium roasts (220 °C), and dark roasts (240 °C). The antioxidants were extracted using methanol as a solvent and the antioxidant activity was examined using the scavenging effect method. It was observed that light-roasted coffee, medium-roasted coffee, and dark-roasted coffee have antioxidant activity µg/g BHA equivalent of 58793.333, 39468.000, and 24721.500 respectively. The light-roasted coffee bean was considered the best result with a score of sensory evaluation of 82.25 which is categorized as a specialty grade of coffee.

Chemical and Biological Characterization of Green and Processed Coffee Beans from Coffea arabica Varieties.

Coffee is one of the most consumed beverages in the world; its production is based mainly on varieties of the Coffea arabica species. Mexico stands out for its specialty and organic coffee. In Guerrero, the production is done by small indigenous community cooperatives that market their product as raw material. Official Mexico Standards stipulate the requirements for its commercialization within the national territory. In this work, the physical, chemical, and biological characterizations of green, medium, and dark roasted beans from C. arabica varieties were carried out. Analysis by HPLC showed higher chlorogenic acid (55 mg/g) and caffeine (1.8 mg/g) contents in the green beans of the Bourbon and Oro Azteca varieties. The caffeine (3.88 mg/g) and melanoidin (97 and 29 mg/g) contents increased according to the level of roasting; a dissimilar effect was found in the chlorogenic acid content (14.5 mg/g). The adequate nutritional content and the sensory evaluation allowed the classification of dark-roasted coffee as premium coffee (84.25 points) and medium-roasted coffee as specialty coffee (86.25 points). The roasted coffees presented antioxidant activity without cytotoxic effects; the presence of CGA and caffeine supports the beneficial effects of drinking coffee. The results obtained will serve as a basis for making decisions on improvements to the coffees analyzed.

A Hybrid Stainless-Steel SPME Microneedle Electrode Sensor for Dual Electrochemical and GC-MS Analysis.

A mechanically robust in-tube stainless steel microneedle solid phase microextraction (SPME) platform for dual electrochemical and chromatographic detection has been demonstrated. The SPME microneedle was fabricated by layer-by-layer (LbL) in-tube coating, consisting of carbon nanotube (CNT)/cellulose nanocrystal (CNC) film layered with an electrically conductive polyaniline (PANI) hydrogel layer (PANI@CNT/CNC SPME microneedle (MN)). The PANI@CNT/CNC SPME MN showed effective analysis of caffeine by GC-MS with an LOD of 26 mg/L and excellent precision across the dynamic range. Additionally, the PANI@CNT/CNC SPME MN demonstrated a 67% increase in sensitivity compared to a commercial SPME fiber, while being highly robust for repeated use without loss in performance. For electrochemical detection, the PANI@CNT/CNC SPME MN showed excellent performance for the detection of 3-caffeoylquinic acid (3-CQA). The dynamic range and limits of detection (LOD) for 3-CQA analysis were 75-448 mg/L and 11 mg/L, respectively. The PANI@CNT/CNC SPME MN was demonstrated to accurately determine the caffeine content and 3-CQA in tea samples and dark roast coffee, respectively. The PANI@CNT/CNC SPME MN was used for semiquantitative antioxidant determination and composition analysis in kiwi fruit using electrochemistry and SPME-coupled GC-MS, respectively.

Impact of roasting on javamide-I/-II in Arabica and Robusta coffee beans

Javamide-I/-II are anti-inflammatory compounds found in coffee beans. However, potential effects of roasting on javamide-I/-II in coffee beans are currently unknown. Therefore, in this paper, the effects of roasting on javamide-I/-II were investigated in Arabica and Robusta beans. Coffee beans were roasted light, medium and dark, and the amounts of javamide-I/-II in the beans were quantified by a HPLC method. The data showed the different amounts of javamide-I/-II in the beans; not detected and ≤ 3.1 mg in Arabica beans, and 0.5–3.7 mg and 1.0–13.8 mg in Robusta beans, respectively. Furthermore, the data showed that roasting process significantly reduced the amounts of javamide-I/-II in both Arabica and Robusta beans (p < 0.05). These data were also confirmed by multivariate analyses. Additionally, these differences were validated in light, medium and dark roast coffee products in the market. Altogether, roasting can have a significant impact on javamide-I/-II amounts in coffee beans.

The effect of post-brew holding time and carafe type on the sensory properties of drip brew coffee.

Coffee quality is believed to degrade quickly after brewing, and retail establishments discard unsold brewed coffee after a specified holding time period, sometimes as short as 30 min. We used trained sensory panels to evaluate the flavor profiles of light, medium, and dark roast coffees held in three different carafe types (glass on hot plate, thermal jacket, and vacuum insulated) for times ranging from 15 min to 3h. Furthermore, a panel of 93 coffee-industry professionals performed a blind evaluation of fresh (30 min) versus held (180 min) coffee for overall liking and attribute level adequacy. Sourness increased over time, consistent with acidity increasing over time (i.e., higher titratable acidity, lower pH), but only for the light and medium roasts. Dark roasted coffee became significantly more acidic over 3 h post-brew but was not perceived as more sour over time by the sensory panel. Variations were observed between the thermal jacket and vacuum carafes for the light and dark roast, but few differences were observed with storage type in the medium roast. Surprisingly, the panel of coffee industry professionals showed no preference for fresh over held. More sensory attributes decreased than increased over time, suggesting that the primary concern with loss of quality during coffee holding may be the loss of volatile aroma compounds. Hedonic ratings suggest that even if the changes over time are noticeable, they may not negatively impact overall liking. © 2022 Society of Chemical Industry.

Water Flow &amp; Temperature Control to Increase Extraction Yield of Light-roasted Coffee Beans

Using light-roasted coffee beans for brewing espresso poses a general problem for pump-based espresso machines. Soluble in light-roasted coffee beans is more challenging to extract and requires a higher EY percentage because it has a relatively higher acidity level than dark-roasted coffee beans. The extraction range of 18% - 22% in light-roasted coffee beans for espresso brewing with an 8% - 12% TDS is qualitatively considered insufficient to produce espresso with a balanced taste. To improve the extraction ability of the espresso machine on coffee soluble. We design two features that hypothetically can solve the problem: Temperature Control Module to increase water temperature stability as a replacement for the thermostat, and Flow Control Module to regulate the speed of the vibration pump by adjusting the voltage resistance to reduce the water pressure/ flow rate used during the initial extraction at the preinfusion phase. Based on the results of trials using an espresso machine that has added temperature and flow control modules, there is an increase in the average percentage of extraction compared to the results of trials using stock machines; the average extraction percentage increased by 4.83 points. Qualitatively, this increase of %EY also significantly impacts the espresso taste, which tasted very sour and unbalanced, became relatively more balanced and comfortable to enjoy.

Simultaneously Verifying the Original Region of Green and Roasted Coffee Beans by Stable Isotopes and Elements Combined with Random Forest

Simultaneously verifying the original region of green and roasted coffee beans is very important for protecting legal interests of the stakeholder according to the chemical analyzing method. 131 green coffee bean samples are collected from six different original regions and pretreated with three degrees (green, middle, and dark roasted); five stable isotope ratios (δ13C, δ14N, δ18O, δ2H, and δ32S) and twelve elemental contents (Al, Cr, Ni, Zn, Ba, Cu, Na, Mn, Fe, Ca, K, and Mg) of green, middle, and dark roasted coffee bean samples (131×3) were analyzed. Fractionation of stable isotopes and variation of elemental contents were evaluated, only isotope hydrogen (2H) significantly fractionated, and elemental concentrations increased with a certain rate during the roasting process. One-way analysis of variance (ANOVA) was used to compare the stable isotope ratios and elemental concentrations of all coffee bean samples from six different original regions. Random forest (RF) was employed to build a discriminating model for simultaneously verifying the original regions of green and roasted coffee bean samples; this model provided 100% accuracy. Inclusion of this mathematical model for simultaneously verifying the original region of green and roasted coffee beans had powerful distinguishing capability and which will not be influenced by fractionation of hydrogen (2H) and variation of element contents during the roasted process.

Impact of roasting degree on sensory profile of Turkish coffee and espresso assessed by Turkish and Brazilian panelists

AbstractThis study aimed to assess the effect of roasting degree and brewing techniques on the sensory profile of Turkish coffee and espresso. Descriptive analysis of coffee samples was carried out for 20 flavor attributes by 10 Turkish and 10 Brazilian assessors. Light, medium, and dark roasted coffee beans were brewed with the decoction method and pressure method. Turkish coffee samples were prepared by automatic machine and cezve, which is the traditional method. The roasting degree and brewing method had a significant impact on the sensory profile of coffee samples. Turkish assessors perceived lightly roasted coffee beverages as sour (6.53 and 6.56 for Turkish coffee with machine and espresso) and pungent notes (7.46 for espresso), while Brazilian assessors perceived them as fruity (5.63 for espresso) and sweet attributes (5.76 and 5.90 for Turkish coffee with cezve and espresso). Roasted (7.83), burnt/acrid (7.96), and bitter (8.13) notes became dominant with the degree of roasting in espresso coffees in the Turkish panel. Brazilian assessors perceived Turkish coffee samples made with cezve and dark roasted beans as roasted (6.53), burnt/acrid (6.66), bitter (6.80), and ashy‐sooty (7.26) notes.Practical applicationsThis research indicates the effect of cultural experience, the degree of roasting, and brewing techniques on the sensory profile of coffee brews. Cultural familiarity and unfamiliarity with Turkish coffee and espresso played an important role in the perceptions of the participants. Variations in descriptive analysis between two country panelists may arise from language and ethnicity differences, oral physiological parameters such as the sensitivity of the somatosensory system, the culinary culture, and eating habits. For the first time, Turkish coffee and espresso coffee brewing techniques were compared by trained Turkish and Brazilian assessors.

Safest Roasting Times of Coffee To Reduce Carcinogenicity

Roasting coffee results in not only the creation of carcinogens such as acrylamide, furan, and polycyclic aromatic hydrocarbons but also the elimination of carcinogens in raw coffee beans, such as endotoxins, preservatives, or pesticides, by burning off. However, it has not been determined whether the concentrations of these carcinogens are sufficient to make either light or dark roast coffee more carcinogenic in a living organism. An Ames test was conducted on light, medium, and dark roast coffee from three origins. We found that lighter roast coffee shows higher mutagenicity, which is reduced to the control level in dark roast coffee varieties, indicating that the roasting process is not increasing mutagenic potential but is beneficial to eliminating the existing carcinogens in raw coffee beans. This result suggests that dark roast coffee is safer and promotes further studies of the various carcinogens in raw coffee that have been burned off.

Infrared spectroscopy coupled with chemometrics in coffee post-harvest processes as complement to the sensory analysis

Sensory evaluation provides subjective information about characteristics related to the crop management and post-harvesting of coffee. Fourier Transform Infrared Spectroscopy (FTIR) quickly and easily detects additional coffee characteristics to those obtained through sensory analysis. This work aimed to complement the sensory evaluation of Specialty coffee by using FTIR and chemometrics. Samples from all three post-harvest methods (dry, semi-dry, and wet) were sensory analysed using the protocol of the Specialty Coffee Association (SCA). Infrared spectra were obtained from samples of green beans, medium roast coffee, and dark roast coffee, previously processed by the three post-harvest methods. Sensory evaluation, according to the SCA quality criteria, classified the coffee obtained from semi-dry process as excellent specialty coffee, and coffees obtained by wet and dry processing methods as very good specialty coffees. PCAs discriminated the post-harvest treatments based on the FTIR data. Recognition based on prediction of samples of the post-harvest treatments by LDAs was over 95%. Results demonstrated that FTIR in combination with multivariate analysis complemented the information obtained from the sensory analysis, and allowed to discriminate and identify the post-harvest treatments for green beans, medium roast coffee, and dark roast coffee.

Evaluation of the inhibition of monoamine oxidase A by bioactive coffee compounds protecting serotonin degradation

Monoamine oxidase A (MAO-A) is a major enzyme responsible for the deamination of neurotransmitters such as serotonin (5-HT) in the central nervous system. The decrease in 5-HT levels is accompanied by disorders at the affective and somatic levels, leading to depression and disorders of the satiety center. The aim of this study was to evaluate the degree of MAO-A inhibition by chlorogenic acids, as well as green, light-, and dark-roasted coffee extracts and bioactive compounds from beans of the species Coffea canephora and Coffea arabica. Data for analysis was obtained using isothermal titration calorimetry and molecular docking. The results showed that caffeine and ferulic acid, as well as green Robusta coffee, demonstrated the greatest inhibition of MAO-A activity, which may increase the bioavailability of serotonin. We believe that green coffee shows potential antidepressant activity by inhibiting MAO-A, and may be used for treating depression and potentially, type 2 diabetes.

Projective mapping: potential tool for sensory evaluation of coffees for industrial application

Sensory analysis is an important tool to control and improve the quality of food products. This study aimed to evaluate the sensory attributes and consumer preference of coffee beverages prepared from roasted ground coffee (Coffea arabica) of different brands sold in Minas Gerais, Brazil, using projective mapping and assess the relationship of sensory attributes and consumer preferences with physicochemical properties. Titratable acidity, pH, soluble solids, color, crude fat, protein, total phenolic content, caffeine, trigonelline, 5-caffeoylquinic acid and caffeic acid were determined. Physicochemical properties showed good agreement with projective mapping data. Samples associated with high acidity in the projective mapping task had the highest levels of 5-caffeoylquinic acid. Coffees associated with bitter/roasted taste and darker colors had typical physicochemical characteristics and color properties of dark-roasted coffee. The sample perceived as thin had the lowest soluble solids content. Consumers preferred traditional, dark-roasted coffee over gourmet, light-roasted coffee. Projective mapping is an effective technique for assessing the sensory attributes of brewed coffee.

Removal of hexavalent chromium from water using hydrochar obtained with different types of feedstock

Hydrochar (HC) was obtained through the hydrothermal digestion of beetroot, carrot, or spent coffee grounds. The yield (i.e., mass of HC produced per mass of feedstock used) was ≈80%, ≈20%, and ≈50% with spent coffee, carrot, and beetroot, respectively. The surface area determined with the Brunauer–Emmett–Teller method was 3.06 m2·g–1 for HC from beetroot, 1.19 m2·g–1 for HC from carrot, 2.84 m2·g–1 for HC from dark roast coffee, and 3.22 m2·g–1 for HC from original roast coffee. Fourier transform infrared spectroscopy experiments showed that amine groups had a significantly higher density in HC produced with spent coffee grounds than that produced using either beetroot or carrot. HC could sorb hexavalent chromium (Cr(VI)) from water. The concentration of Cr(VI) in water decreased from 0.3 ppm to ≈0.07 ppm and to ≈0.1 ppm within 90 min using 20 g·L–1 of HC made from spent coffee grounds and from beetroot and carrot, respectively.

Coffee Drinking and Emotions: Are There Key Sensory Drivers for Emotions?

In the past couple of decades the coffee market has exploded, and to remain competitive, it is important to identify the key drivers for consumer acceptance of coffee. This study expanded on the previous emotion study on a population of coffee drinkers in Manhattan, Kansas, USA and focused on identifying the sensory drivers of emotional responses elicited during the coffee drinking experience (CDE). A trained coffee panel performed a descriptive analysis of six coffee samples and identified the key sensory attributes that discriminated each coffee. Utilizing Partial Least Square Regression (PLSR), the descriptive data were then mapped with the emotion data to identify sensory drivers for eliciting the emotional responses. The sensory characteristics of dark roast coffee (roast–aroma and flavor, burnt–aroma and flavor, bitter, and body) might elicit positive-high energy feelings for this population of coffee users. Tobacco (flavor) and cocoa (aroma) may also be responsible for positive emotions (content, good, and pleasant). Citrus and acidity seemed to be negative sensory drivers as they induced the feeling of off-balance. Sensory descriptive data could be useful to describe emotion profiles elicited by coffee drinking, which could help the coffee industry create coffee products for different segments of coffee drinkers.

Daily consumption of a dark-roast coffee for eight weeks improved plasma oxidized LDL and alpha-tocopherol status: A randomized, controlled human intervention study

Abstract Scope Coffee consumption is widely recognized to improve the antioxidant status. We hypothesized a dark-roast coffee to reduce plasma oxidized LDL (oxLDL) and to improve alpha-tocopherol concentrations. Methods and results After a 4 week, coffee-free run-in period, 86 healthy, randomized volunteers completed either a control (CTRL) or coffee (COFF) intervention in which either 750 mL water (CTRL) or coffee (COFF) were consumed daily for 8 weeks. Blood samples were taken at the begin and after the intervention. Mean changes in oxidized LDL concentrations after coffee consumption (−0.47 ± 15.4 U/L) differed from those of the CTRL-G (5.69 ± 18.8 U/L, p Conclusion Improved plasma alpha-tocopherol levels and reduced levels of plasma oxLDL after 8 week consumption of a dark-roast coffee rich in N-methylpyridinium are hypothesized to be caused by coffee-induced lipolysis, resulting in increased alpha-tocopherol mobilisation.

Consumption of a dark roast coffee blend reduces DNA damage in humans: results from a 4-week randomised controlled study.

To determine the DNA protective effects of a standard coffee beverage in comparison to water consumption. The single-blind, randomised controlled study with parallel design included healthy women (n = 50) and men (n = 50) recruited from the general Central European population. The subjects were randomised in a coffee and a control group, with stratification for sex and body mass index. The study comprised two periods of 4weeks: a preconditioning period, with daily consumption of at least 500ml water but no coffee, nor tea, nor any other caffeine-containing product. During the subsequent intervention period the coffee group consumed 500ml of freshly brewed dark roast coffee blend per day, the control group consumed water instead. On the last day of each period, blood was drawn and analysed by comet assay (single-cell gel electrophoresis) to assess the level of DNA damage (strand breakage). At the end of the intervention period the mean level of DNA strand breaks in the coffee group has decreased in comparison to the control group [difference in means 0.23% TI (tail intensity), p = 0.028]. The mean change from baseline (delta value) was - 23% in the coffee group (p = 0.0012). Effects of coffee intake were similar for men and women. During intervention, neither group showed any significant change in body weight or calorie intake. Our results indicate that regular consumption of a dark roast coffee blend has a beneficial protective effect on human DNA integrity in both, men and women.