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At least 613 records · Page 34Linked to original sources
PubMed2006

Characterization of galactomannan derivatives in roasted coffee beverages.

In this work, the galactomannans from roasted coffee infusions were purified by 50% ethanol precipitation, anion exchange chromatography, and phenylboronic acid-immobilized Sepharose chromatography. Specific enzymatic hydrolysis of the beta-(1-->4)-D-mannan backbone allowed us to conclude that the galactomannans of roasted coffee infusions are high molecular weight supports of low molecular weight brown compounds. Also, the molecular weight of the brown compounds linked to the galactomannan increases with the increase of the coffee degree of roast. The reaction pathways of galactomannans during the coffee roasting process were inferred from the detection of specific chemical markers by gas chromatography-electron impact mass spectrometry and/or electrospray ionization tandem mass spectrometry. Maillard reaction, caramelization, isomerization, oxidation, and decarboxylation pathways were identified by detection of Amadori compounds, 1,6-beta-anhydromannose, fructose, glucose, mannonic acid, 2-ketogluconic acid, and arabinonic acid in the reducing end of the obtained oligosaccharides. The implication of the several competitive reaction pathways is discussed and related to the structural changes of the galactomannans present in the roasted coffee infusions.

Chromatography, Gas↗
PubMed2006

Synthesis and structure determination of covalent conjugates formed from the sulfury-roasty-smelling 2-furfurylthiol and di- or trihydroxybenzenes and their identification in coffee brew.

Recent investigations demonstrated that the reaction of odor-active thiols such as 2-furfurylthiol with thermally generated chlorogenic acid degradation products is responsible for the rapid aroma staling of coffee beverages. To get a clear understanding of the molecular mechanisms underlying this aroma staling, the existence of putative phenol/thiol conjugates needs to be verified in coffee. The aim of the present study was therefore to synthesize such conjugates for use as reference substances for LC-MS screening of coffee. To achieve this, catechol, 3-methyl-, 4-methyl-, and 4-ethylcatechol, pyrogallol, hydroxyhydroquinone, 5-O-caffeoylquinic acid, and caffeic acid, respectively, were reacted with 2-furfurylthiol in the presence of iron(III) chloride and air oxygen. After purification, the structures of 25 phenol/thiol conjugates were identified by means of LC-MS/MS and 1D/2D NMR experiments. Using these compounds as reference materials, four conjugates, namely, 3-((2-furylmethyl)sulfanyl)catechol, 3-((2-furylmethyl)sulfanyl)-5-ethylcatechol, 4-((2-furylmethyl)sulfanyl)hydroxyhydroquinone, and 3,4-bis((2-furylmethyl)sulfanyl) hydroxyhydroquinone, were identified for the first time in coffee brew by means of HPLC-MS/MS(MRM). These findings clearly demonstrate catechol, 4-ethylcatechol, and hydroxyhydroquinone as the primary thiol trapping agents involved in the aroma staling of coffee beverages.

Chromatography, High Pressure Liquid↗
PubMed2000

In vitro antioxidant and ex vivo protective activities of green and roasted coffee.

The antioxidant properties of green and roasted coffee, in relation to species (Coffea arabica and Coffea robusta) and degree of roasting (light, medium, dark), were investigated. These properties were evaluated by determining the reducing substances (RS) of coffee and its antioxidant activity (AA) in vitro (model system beta-carotene-linoleic acid) and ex vivo as protective activity (PA) against rat liver cell microsome lipid peroxidation measured as TBA-reacting substances. RS of C. robustasamples were found to be significantly higher when compared to those of C. arabica samples (p < 0.001). AA for green coffee samples were slightly higher than for the corresponding roasted samples while PA was significantly lower in green coffee compared to that of all roasted samples (p < 0.001). Extraction with three different organic solvents (ethyl acetate, ethyl ether, and dichloromethane) showed that the most protective compounds are extracted from acidified dark roasted coffee solutions with ethyl acetate. The analysis of acidic extract by gel filtration chromatography (GFC) gave five fractions. Higher molecular mass fractions were found to possess antioxidant activity while the lower molecular mass fractions showed protective activity. The small amounts of these acidic, low molecular mass protective fractions isolated indicate that they contain very strong protective agents.

Animals↗
PubMed2004

Effects of coffee consumption on oxidative susceptibility of low-density lipoproteins and serum lipid levels in humans.

Since little is known about how coffee intake affects low-density lipoprotein (LDL) oxidative susceptibility and serum lipid levels, we conducted an in vivo study in 11 healthy male students of Wakayama Medical University aged between 20 and 31 years fed an average Japanese diet. On days 1-7 of the study, the subjects drank mineral water. On day 7, the subjects began drinking coffee, 24 g total per day, for one week. This was followed by a one week "washout period" during which mineral water was consumed. Fasting peripheral venous blood samples were taken at the end of each one-week period. LDL oxidation lag time was approximately 8% greater (p < 0.01) after the coffee drinking period than the other periods. Serum levels of total cholesterol and LDL-cholesterol (LDL-C) and malondialdehyde (MDA) as thiobarbituric acid reactive substances (TBARS) were significantly decreased after the coffee drinking period. Finally, regular coffee ingestion may favorably affect cardiovascular risk status by modestly reducing LDL oxidation susceptibility and decreasing LDL-cholesterol and MDA levels.

Adult↗
PubMed2004

Coffee, tea and caffeine and risk of epithelial ovarian cancer.

OBJECTIVE: Studies evaluating the relationships between coffee, tea and caffeine and ovarian cancer risk have given inconsistent results. We have examined these associations using data from an Australian population-based case-control study. METHODS: Women with epithelial ovarian cancer (EOC) (n = 696) and control women selected from the Electoral Roll (n = 786) provided comprehensive reproductive and lifestyle data and completed a food frequency questionnaire. RESULTS: Increasing coffee consumption was associated with a decreased risk of invasive EOC ( p trend = 0.009) with an odds ratio (OR) of 0.51 (95% confidence interval (CI) 0.32-0.80) for consumption of >/=4 cups of coffee per day compared to non-drinkers. The association was significant only for serous and endometrioid/clear cell histological subtypes. There was no association with borderline tumours (OR: 1.20, 95% CI: 0.58-2.47). An inverse relationship was also seen between caffeine intake and EOC but tea consumption was not related to EOC (OR: 1.10 95% CI: 0.76-1.61 for >/=4 cups/day versus none). CONCLUSIONS: As tea contributed significantly to caffeine intake in this population we conclude that the association we observed with coffee is not due to caffeine, but to other components within coffee. We suggest future studies consider the type as well as the amount of each beverage consumed.

Australia↗
PubMed1989

Cardiovascular reactivity, mood, and task performance in deprived and nondeprived coffee drinkers.

Forty habitual, heavy coffee drinkers (M = 5.7 cups/day) participated in two experimental sessions. Participants were deprived of their morning coffee for one of the laboratory sessions, not deprived the other. During each session, subjects consumed 12 oz of caffeinated coffee, decaffeinated coffee, or caffeine-free herbal tea. Measurements of heart rate, blood pressure, mood, and catecholamine response to deprivation and consumption of the beverage, alone and in combination with challenging tasks, were made. This study found that caffeine continues to cause blood pressure increases with chronic, heavy consumption and that these effects do not appear to habituate with regular use. Subjects reacted to behavioral challenge with fewer negative mood effects if they had consumed caffeine or coffee. Mild caffeine deprivation was associated with symptoms of stress.

Adolescent↗
PubMed2006

Joint association of coffee consumption and other factors to the risk of type 2 diabetes: a prospective study in Finland.

OBJECTIVE: To examine joint associations of coffee consumption and other factors (including physical activity, obesity and alcohol consumption) with the risk of type 2 diabetes. DESIGN: Prospective follow-up study. SUBJECTS: In all, 10 188 Finnish men and 11 197 women aged 35-74 years without a history of stroke, coronary heart disease or diabetes at baseline. MEASUREMENT: A self-administered questionnaire data on coffee, tea, alcohol and other food consumption, physical activity, smoking, socio-economic factors and medical history, together with measured height, weight and blood pressure using standardized protocol. RESULTS: During a mean follow-up of 13.4 years, there were 964 incident cases of type 2 diabetes. Multivariate-adjusted (age, study year, systolic blood pressure, education, smoking, physical activity, body mass index (BMI) and fruit, vegetable, sausage, bread, alcohol and tea consumption) hazard ratio of type 2 diabetes in participants who drank 0-2, 3-6 and > or =7 cups of coffee were 1.00, 0.77 and 0.66 (P=0.022 for trend) in men, 1.00, 0.71 and 0.52 (P=0.001 for trend) in women, and 1.00, 0.75 and 0.61 (P<0.001 for trend) in men and women combined (adjusted also for sex), respectively. This inverse association was consistent in subjects with any joint levels of physical activity and BMI, and in alcohol drinkers and non-drinkers. Among obese and inactive people, coffee drinking of seven cups or more daily reduced the risk of type 2 diabetes to half. CONCLUSIONS: Coffee drinking was associated with a reduced risk of type 2 diabetes in both men and women, and this association was observed regardless of the levels of physical activity, BMI and alcohol consumption.

Adult↗
PubMed2004

Coffee and incidence of diabetes in Swedish women: a prospective 18-year follow-up study.

OBJECTIVES: To examine the long-term incidence of diabetes in relation to coffee consumption in Swedish women. DESIGN: Prospective longitudinal cohort study. SETTING: City of Göteborg, Sweden. SUBJECTS: A random population sample of 1361 women, aged 39-65 years, without prior diabetes or cardiovascular disease took part in a screening study in 1979-1981 with questionnaires, physical examination and blood sampling. MAIN OUTCOME MEASURES: The development of diabetes until 1999 was identified by questionnaires in a second screening and the Swedish hospital discharge register. RESULTS: Altogether, there were 74 new cases of diabetes. The risk of developing diabetes was 475 per 100 000 person-years in women who consumed two cups of coffee or less per day, 271 in women who consumed three to four cups per day, 202 with a consumption of five to six cups per day, and 267 in drinkers of seven cups or more per day. Associated hazard ratios, after adjustment for age, smoking, low physical activity, education and body mass index were 0.55 (0.32-0.95), 0.39 (0.20-0.77) and 0.48 (0.22-1.06) for daily consumption of three to four, five to six and seven cups or more, respectively, with a consumption of less than two per day as reference. Additional adjustment for serum cholesterol and triglycerides attenuated the relation between coffee and diabetes slightly, indicating a possible mediating effect on the effect of coffee by serum lipids. CONCLUSIONS: The findings of the present study support the hypothesis that coffee consumption protects from the development of diabetes in women.

Adult↗
PubMed2002

Benign prostatic hyperplasia: the opposite effects of alcohol and coffee intake.

OBJECTIVE: To assess several lifestyle factors influencing benign prostatic enlargement and therefore the severity of benign prostatic hyperplasia (BPH). SUBJECTS AND METHODS: In age-stratified cohorts from population-based random samples of 882 men (aged 65, 70, 75 and 80 years) each participant completed a standardized questionnaire, including weight, height, socio-economic status, use of cigarettes, alcohol and coffee consumption. The questionnaire also elicited detailed information on the medical history of prostatic and (over the past month) lower urinary tract symptoms, applying all questions from the American Urology Association instrument. The lifestyle variables were evaluated for confounding by multiple logistic regression, controlling for age, relative weight and professional education, with those classified as having BPH analysed as the dependent variable. RESULTS: The prevalence of surgery for BPH increased with age from 15% at 65 years to 41% at 80 years. There was a strong inverse association between alcohol intake and men treated surgically for BPH or in 'watchful waiting' for surgical intervention, but a positive correlation with coffee consumption, and although not significantly, with the number of cigarettes smoked. Nevertheless, those who had never smoked have a slightly greater risk of BPH than current smokers. The body mass index and professional education were not associated with the risk of BPH. CONCLUSIONS: Given the opposite effects of coffee and moderate alcohol consumption, together with the increased risk for clinical BPH in men with coronary heart disease, coffee constituents, which increase the serum concentration of low-density lipoprotein cholesterol, may be involved in the pathophysiology of BPH. Further epidemiological studies are needed to evaluate whether avoiding coffee intake reduces the risk of BPH.

Aged↗
PubMed1981

Coffee and cancer of the pancreas.

We questioned 369 patients with histologically proved cancer of the pancreas and 644 control patients about their use of tobacco, alcohol, tea, and coffee. There was a weak positive association between pancreatic cancer and cigarette smoking, but we found no association with use of cigars, pipe tobacco, alcoholic beverages, or tea. A strong association between coffee consumption and pancreatic cancer was evident in both sexes. The association was not affected by controlling for cigarette use. For the sexes combined, there was a significant dose-response relation (P approximately 0.001); after adjustment for cigarette smoking, the relative risk associated with drinking up to two cups of coffee per day was 1.8 (95% confidence limits, 1.0 to 3.0), and that with three or more cups per day was 2.7 (1.6 to 4.7). This association should be evaluated with other data; if it reflects a causal relation between coffee drinking and pancreatic cancer, coffee use might account for a substantial proportion of the cases of this disease in the United States.

Aged↗
PubMed1982

No association between coffee consumption and adverse outcomes of pregnancy.

We analyzed interview and medical-record data of 12,205 non-diabetic, non-asthmatic women to evaluate the relation between coffee consumption and adverse outcomes of pregnancy. Low birth weight and short gestation occurred more often among offspring of women who drank four or more cups of coffee a day and more often among the offspring of smokers. After controlling for smoking, other habits, demographic characteristics, and medical history by standardization and logistic regression, we found no relation between low birth weight or short gestation and heavy coffee consumption. Furthermore, there was no excess of malformations among coffee drinkers. These negative results suggest that coffee consumption has a minimal effect, if any, on the outcome of pregnancy.

Adult↗
PubMed1983

The Tromsø heart study. Does coffee raise serum cholesterol?

We examined the relation between coffee consumption and levels of serum total cholesterol, high-density-lipoprotein (HDL) cholesterol, and triglycerides in a population of 7213 women and 7368 men between the ages of 20 and 54 years. Coffee consumption was positively associated with levels of total cholesterol and triglycerides in both sexes and was inversely associated with levels of HDL cholesterol in women. The coffee-cholesterol relation remained strong and statistically significant (P less than 0.0001 in a covariance analysis) after adjustment for age, logarithm of body-mass index, physical activity in leisure time, cigarette smoking, and alcohol consumption. After adjustment for all covariates, the total cholesterol level was 5.56 +/- 0.05 mmol per liter (mean +/- S.E.) in men drinking less than one cup of coffee a day, as compared with 6.23 +/- 0.03 mmol per liter in those consuming more than nine cups a day. The corresponding figures for women were 5.32 +/- 0.05 and 5.92 +/- 0.04 mmol per liter. None of the other variables considered could explain this relation. We conclude that coffee consumption is a major contributor to the variation in levels of total cholesterol.

Adult↗
PubMed2001

Daily intake of trace metals through coffee consumption in India.

The trace element contents of five varieties of instant coffee powder available in the Indian market have been analysed. Ca, Cr, Fe, K, Mg, Mn, Ni, Sr, Zn and Pb, Cd, Cu have been determined using atomic absorption spectrophotometry and differential pulse anodic stripping voltammetry, respectively. The metal levels in the coffee powders observed in this study are comparable with those reported for green coffe beans (Arabica and Robusta variety) reported worldwide with the exception of Sr and Zn, which were on the lower side of the reported values. Concentrations of these metals have been converted into intake figures based on coffee consumption. The daily intakes of the above metals through ingestion of coffee are 1.4 mg, 1.58 microg, 124 microg, 41.5 mg, 4.9 mg, 17.9 microg, 2.9 microg, 3.8 microg, 12.5 microg, 0.2 microg, 0.03 microg and 15.5 microg, respectively. The values, which were compared with the total dietary, intake of metals through ingestion by the Mumbai population, indicate that the contribution from coffee is less than or around 1% for most of the elements except for Cr and Ni which are around 3%.

Coffee↗
PubMed2001

Ochratoxin A (OTA) in coffee: nation-wide evaluation of data collected by German Food Control 1995-1999.

The evaluation process involved data collected by Official Food Control Laboratories during the period 1995 until 1999. A total of 613 samples analysed for ochratoxin A and complying with a detection limit lower than 0.6 microg/kg were evaluated. With the assistance of statistical process analysis the median concentrations for green coffee (0.4 microg/kg), for roasted coffee (0.6 microg/kg), for decaffeinated roasted coffee along with low-acid decaffeinated roasted coffee (0.4 microg/kg) as well as for soluble coffee (0.7 microg/kg) were determined. The result is a mean daily total intake per consumer of 9 ng OTA.

Carcinogens↗
PubMedDate not supplied

A study of the contamination by ochratoxin A of green and roasted coffee beans.

A study was performed to evaluate the contamination by ochratoxin A in coffee beans. Twenty-nine samples of green coffee were collected from large lots of material by representative sampling. The analyses of green coffee samples showed a significantly high contamination percentage (58%) ranging from 0.2 to 15 micrograms/kg. Naturally and artificially contaminated samples were roasted at different operation times (5-6 min) to verify the percentage of destruction of the mycotoxin. The percentage ranged from 48% to 87% and from 90% to 100% in artificially and naturally contaminated samples respectively. The beverages prepared from artificially contaminated coffee using the most common types of coffee makers showed no residues of ochratoxin A.

Chromatography, High Pressure Liquid↗
PubMed1999

Effect of coffee oil and its unsaponifiable fraction on plasma cholesterol level in female rats.

The present study was conducted to identify the cholesterol-raising factor in coffee oil besides the other two well-known diterpenes, cafestol and kahweol. Female rats fed coffee oil for 4 weeks showed significantly higher level of plasma cholesterol (P < 0.01) and triacylglycerols (P < 0.01). Feeding unsaponifiable lipids of coffee oil caused significant decrease in plasma cholesterol; however, increase in triacylglycerol was observed. Rats given beta-sitosterol showed increase in plasma triacylglecerol and decrease in cholesterol levels, an effect similar to that observed with unsaponifiable lipids. beta-sitosterol is the major constituent of unsaponifiable lipids of the coffee oil. These results show that cafestol and kahweol diterpene alcohols are not the only cholesterol-raising factors in coffee oil.

Analysis of Variance↗
PubMed1979

The effect of coffee consumption on plasma lipids, lipoproteins, and the development of aortic atherosclerosis in rhesus monkeys fed an atherogenic diet.

Rhesus monkeys (seven females and six males) were fed ad libitum a diet comparable to that consumed by humans, containing 25% by weight fat (40% of calories) and 0.15% cholesterol (0.3 mg/kcal) for 12 months (phase 1). From the 13th month all monkeys were continued on the diet while four females and three males were given 50% coffee as their fluid intake and the remainder were water controls (phase 2). Major changes in total plasma lipids and lipoprotein profiles occurred within 3 months and generally plateaued thereafter. Total plasma protein remained constant while total plasma cholesterol, phospholipids, triglycerides, and free fatty acid levels increased. After the initiation of coffee, there was no difference between the diet-water group and the diet-coffee group with respect to total protein and lipids in plasma. Total concentrations of plasma lipoproteins varied throughout the study. The pre-beta (very low density lipoproteins) fraction remained constant while the beta (low density lipoprotein) and alpha (high density lipoprotein) fractions, along with their major components, increased within 3 to 6 months, then fluctuated in absolute weight thereafter. The introduction of 50% coffee was without effect on the dynamic changes in these fractions as fluctuations were found in both groups and to the same magnitude. This leads the authors to suspect that such variations are "normal" or are in response to the diet per se. The atherogenic diet induced fatty streaks in the aortas of all monkeys to a greater extent in males than females. However, there were no gross differences in the quantity or distribution of the streaks between control and coffee-drinking monkeys.

Alanine Transaminase↗
PubMed1997

Separate effects of the coffee diterpenes cafestol and kahweol on serum lipids and liver aminotransferases.

The coffee diterpene cafestol occurs in both robusta and arabica beans. It is present in unfiltered coffee brews and raises serum concentrations of cholesterol, triacylglycerols, and alanine aminotransferase in humans. The effects are linear with the cafestol dose. Unfiltered coffee also contains the related compound kahweol, which occurs only in the major coffee strain arabica. The activity of kahweol is unknown. In a randomized, double-blind crossover study, we gave 10 healthy male volunteers either pure cafestol (61-64 mg/d) or a mixture of cafestol (60 mg/d) and kahweol (48-54 mg/d) for 28 d. Relative to baseline values, cafestol raised mean (+/-SEM) total serum cholesterol concentrations by 0.79 +/- 0.14 mmol/L (31 +/- 5 mg/dL), low-density-lipoprotein (LDL) cholesterol by 0.57 +/- 0.13 mmol/L (22 +/- 5 mg/dL), fasting triacy-glycerols by 0.65 +/- 0.12 mmol/L (58 +/- 11 mg/dL), and alanine aminotransferase by 18 +/- 2 U/L (all P < 0.01). Relative to cafestol alone, the mixture of cafestol plus kahweol increased total cholesterol by another 0.23 +/- 0.16 mmol/L (9 +/- 6 mg/dL) (P = 0.08), LDL cholesterol by 0.23 +/- 0.16 mmol/L (9 +/- 6 mg/dL) (P = 0.09), triacylglycerols by 0.09 +/- 0.10 mmol/L (8 +/- 9 mg/dL) (P = 0.20), and alanine aminotransferase by 35 +/- 11 U/L (P = 0.004). Thus, the effect of cafestol on serum lipid concentrations was much larger than the additional effect of kahweol, and the hyperlipidemic potential of unfiltered coffee mainly depends on its cafestol content. Both cafestol and kahweol raised alanine aminotransferase concentrations, and their hyperlipidemic effect thus seems not to be coupled with their effect on liver cells.

Administration, Oral↗