Filter Coffee Research Articles

Assessment of antimicrobial activity of coffee brewed in three different ways from different origins

The antimicrobial effect against pathogens such as Staphylococcus aureus, Enterecoccus faecalis, Listeria monocytogenes, Pseudomonas aeruginosa, Escherichia coli and Salmonellacholeraesius was determined in four types of coffee (Coffea arabica L. cv. Colombia, decaffeinated cv. Colombia, cv. Ethiopia and cv. Kenya). Coffee was seen to have significant activity against the growth of food spoilage bacteria. Among the Gram-positive bacteria, coffee was strongly active against S. aureus, moderately active against L. monocytogenes and had a slightly inhibitory effect against E. faecalis. However, coffee samples were found to be less active against Gram-negative bacteria. The results show that espresso Colombia coffee has better antimicrobial activity than filter and Italian coffee with significant differences (p < 0.05). Taking into account the origin, there were significant differences (p < 0.05) between Kenya and decaffeinated Colombia, on the one hand, and Ethiopia and Colombia coffee, on the other, the two last showing the highest antimicrobial activity. The antimicrobial activity of the coffee from different origins studied in this paper increased with concentration. Typical coffee compounds were also analysed, and only caffeic and chlorogenic acids showed any inhibitory effect against the growth of all the analysed bacteria. The antibacterial properties of coffee means that it has a promising potential as natural food ingredient to extend the shelf life of foods such as cake, cookies or biscuits, coffee flavoured with shakes, yoghurt.

Identification of hydrogen peroxide as a major cytotoxic component in Maillard reaction mixtures and coffee

The cytotoxic activity of Maillard reaction products and coffee was studied using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay and the neutral red uptake (NRU) assay. Equimolar mixtures of sugars and lysine were heated at 120 degrees C and used to stimulate bovine aorta endothelial cells for 24 h. The cytotoxic activity increased with increase in educt concentration and heating time. Mixtures containing ribose were most active, followed by lactose and glucose. Hydrogen peroxide, which was present in the Maillard mixtures in concentrations between 7 and 87 microM, was identified as one of their major cytotoxic components. H2O2-concentrations increased further up to 130 microM under cell culture conditions. Filter coffee, espresso, and green coffee extract reduced cell viability significantly to 10, 19, and 83% of PBS-treated control. The effect was largely attenuated by the addition of catalase. Nil, 33, and 41 microM H2O2 was measured in green coffee extract, filter coffee, and espresso, respectively, increasing to 13, 369, and 333 microM during cell culture conditions. No additional H2O2 formation was detected when coffee was incubated for up to 5 h without further treatment. In conclusion, hydrogen peroxide is a major product in Maillard mixtures and coffee inducing cell death in vitro.

Life cycle assessment of spray dried soluble coffee and comparison with alternatives (drip filter and capsule espresso)

This paper aims to evaluate the environmental burdens associated with spray dried soluble coffee over its entire life cycle and compare it with drip filter coffee and capsule espresso coffee. It particularly aims to identify critical environmental issues and responsibilities along the whole life cycle chain of spray dried coffee. This life cycle assessment (LCA) specifically uses foreground data obtained directly from coffee manufacturers and suppliers. Aside from energy consumption and greenhouse gases emissions, water footprint is also studied in detail, including regionalization of water impacts based on the ecological scarcity method 2006. Other impact categories are screened using the IMPACT 2002+ impact assessment method. The overall LCA results for a 1 dl cup of spray dried soluble coffee amounts approximately to 1 MJ of primary non-renewable energy consumption, to emissions of 0.07 kg of CO 2-eq, and between 3 and 10 l of non-turbined water use, depending on whether or not the coffee cultivation is irrigated and wet treated. When considering turbined water, use can be up to 400 l of water per cup. Pouch – and to a lesser extent metal can packaging alternatives – show lower environmental burdens than glass or sticks. On average, about one half of the environmental footprint occurs at a life cycle stage under the control of the coffee producer or its suppliers (i.e., during cultivation, treatment, processing, packaging up to distribution, along with advertising) and the other half at a stage controlled by the user (shopping, appliances manufacturing, use and waste disposal). Key environmental parameters of spray dried soluble coffee are the amount of extra water boiled and the efficiency of cup cleaning during use phase, whether the coffee is irrigated or not, as well as the type and amount of fertilizer used in the coffee field. The packaging contributes to 10% of the overall life cycle impacts. Compared to other coffee alternatives, spray dried soluble coffee uses less energy and has a lower environmental footprint than capsule espresso coffee or drip filter coffee, the latter having the highest environmental impacts on a per cup basis. This study shows that a broad LCA approach is needed to help industry to minimize the environmental burdens directly related to their products. Including all processes of the entire system is necessary i) to get a comprehensive environmental footprint of the product system with respect to sustainable production and consumption, ii) to share stakeholders responsibility along the entire product life cycle, and iii) to avoid problem shifting between different life cycle stages.

Dietary Fiber from Coffee Beverage: Degradation by Human Fecal Microbiota

Arabinogalactans and galactomannans from coffee beverages are part of the dietary fiber complex. Chemical structures and fermentability of soluble dietary fiber obtained from a standard filter coffee beverage (Coffea arabica, origin Colombia, medium roasted) by human intestinal bacteria were investigated. One cup (150 mL) of filter coffee contained approximately 0.5 g of soluble dietary fiber (enzymatic-gravimetric methodology), 62% of which were polysaccharides. The remainder was composed of Maillard reaction products and other nonidentified substances. Galactomannans and type II arabinogalactans were present in almost equal proportions. Coffee dietary fiber was readily fermented by human fecal slurries, resulting in the production of short-chain fatty acids (SCFA). After 24 h of fermentation, 85% of total carbohydrates were degraded. In general, arabinosyl units from the polysaccharide fraction were degraded at a slower rate than mannosyl and galactosyl units. In the process of depolymerization arabinogalactans were debranched and the ratio of (1-->3)-linked to (1-->6)-linked galactosyl residues decreased. Structural units composed of (1-->5)-linked arabinosyl residues were least degradable, whereas terminally linked arabinosyl residues were easily utilized. The impact of coffee fiber on numerically dominant population groups of the intestinal microbiota was investigated by fluorescence in situ hybridization combined with flow cytometry (FISH-FC). After 24 h of fermentation, an increase of about 60% of species belonging to the Bacteroides-Prevotella group was observed. The growth of bifidobacteria and lactobacilli was not stimulated.

Changes in Headspace Volatile Concentrations of Coffee Brews Caused by the Roasting Process and the Brewing Procedure

Headspace-solid-phase microextraction technique (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to characterize the aroma compounds of coffee brews from commercial conventional and torrefacto roasted coffee prepared by filter coffeemaker and espresso machine. A total of 47 volatile compounds were identified and quantified. Principal component analysis (PCA) was applied to differentiate coffee brew samples by volatile compounds. Conventional and torrefacto roasted coffee brews were separated successfully by principal component 1 (68.5% of variance), and filter and espresso ones were separated by principal component 2 (19.5% of variance). By GC olfactometry, a total of 34 aroma compounds have been perceived at least in half of the coffee extracts and among them 28 were identified, among which octanal was identified for the first time as a contributor to coffee brew aroma.

Antioxidant capacity of coffees of several origins brewed following three different procedures

The antioxidant capacity of coffees (Arabica and Robusta) from 12 different points of origin (Uganda, Papua, Jamaica, Ethiopia, Kenya, Puerto Rico, “Caracolillo” Puerto Rico, Nicaragua, Colombia, Vietnam, Brazil and Guatemala) and two decaffeinated coffees from Colombia and Brazil prepared by three commonly used procedures (espresso, filter and Italian) were evaluated and compared with antioxidant standards and other phenolic compounds which have been described in coffee. All the coffees studied were very effective as scavengers of lipoperoxyl and OH radicals. The results also showed that there are no significant differences ( p < 0.05) between the three ways of brewing (espresso, filter and Italian). The H 2O 2 scavenging capacity was analysed in freshly made coffee and 6 h later, the antioxidant activity slightly increasing with time. The filtered coffee showed a greater capacity to react with H 2O 2 ( p < 0.05) than the Italian and espresso coffees. All the coffee samples improved the oxidative stability of butter (Rancimat test), espresso and Italian coffee providing greater protection ( p < 0.05) than the filtered beverages. The coffee beverages from different origins did not show significant differences during 28 days of storage as regards the autoxidation of linoleic acid. However, filter brews produced stronger antioxidant activity ( p < 0.05) during storage than espresso and Italian brewing techniques. The TEAC value provided a ranking in decreasing order of antioxidant capacity for samples at 6 min: Vietnam, Uganda, Nicaragua, Colombia, Brazil, “caracolillo”, Puerto Rico, Guatemala, Kenya, Papua, decaffeinated Colombia, Ethiopia, Jamaica, and decaffeinated Brazil. In general, decaffeinated coffees (Colombia and Brazil) showed lower TEAC values than coffees with caffeine. Filter and Italian coffee analysed after 6 min exhibited higher TEAC value than espresso coffees. All the coffees studied are good antioxidants regardless of their cost, origin and way in which they are brewed (espresso, filter or Italian), which is a point worth considering.

Whitening and sweetening influences on filter coffee preference

As a basis for development of new, and rationalisation of existing products, consumer preferences in commercial filter coffees were examined in a quantitative approach with multivariate mapping. Coffees were brewed from 12 ground bean blends and served to 150 consumers as drunk normally – black, whitened and/or sweetened. In a complete block design with two sessions of six coffees, employing randomisation to reduce order effects, hedonic data on a five‐point scale were collected then processed using Q‐mode principal component analysis yielding preference maps for each presentation. Conventional descriptive profiling provided information on blend characters allowing soft modelling to determine sensory attributes driving preference scoring. From univariate data analyses, gender was a significant factor for presentation style: addition of milk increased preference scores for blends in males and sugar reduced preference ratings for females. The outcome was a series of consumer segmentations for different coffee presentations.

Measuring caffeine-induced changes in middle cerebral artery blood velocity using transcranial Doppler in patients recovering from ischaemic stroke

Acute ingestion of caffeine is known to reduce cerebral blood flow in normal volunteers and in certain patient groups. There is no evidence that this causes problems in the normal population. However, there may be implications if a similar reduction occurs in patients recovering from an ischaemic stroke, in whom local blood flow has already been reduced.Transcranial Doppler provides a non-invasive method for measuring changes in middle cerebral artery (mca) blood velocity. A method for obtaining consistent, reliable measurements was developed and used in a double blind, randomized, crossover study on 20 patients (18 M, 2 F, mean age 70) recovering from ischaemic stroke in the mca territory. Middle cerebral artery blood velocity was measured bilaterally using transcranial Doppler before and after 250 mg caffeine (equivalent to about two cups of filter coffee) or matched placebo.Caffeine caused an average 12% reduction in blood velocity compared to placebo in the hemisphere affected by the stroke (95% CI 8%–16%, p < 0.000 01), and a 12% reduction in the non-affected hemisphere (95% CI 6%–18%, p < 0.001). The clinical implications are unclear at present, and imaging techniques will be required to establish whether caffeine does reduce flow to hypo-perfused regions.

The detection of caffeine in a variety of beverages using Curie-point pyrolysis mass spectrometry and genetic programming

Freeze dried coffee, filter coffee, tea and cola were analysed by Curie-point pyrolysis mass spectrometry (PyMS). Cluster analysis showed, perhaps not surprisingly, that the discrimination between coffee, tea and cola was very easy. However, cluster analysis also indicated that there was a secondary difference between these beverages which could be attributed to whether they were caffeine-containing or decaffeinated. Artificial neural networks (ANNs) could be trained, with the pyrolysis mass spectra from some of the freeze dried coffees, to classify correctly the caffeine status of the unseen spectra of freeze dried coffee, filter coffee, tea and cola in an independent test set. However, the information in terms of which masses in the mass spectrum are important was not available, which is why ANNs are often perceived as a ‘black box’ approach to modelling spectra. By contrast, genetic programs (GPs) could also be used to classify correctly the caffeine status of the beverages, but which evolved function trees (or mathematical rules) enabling the deconvolution of the spectra and which highlighted that m/z 67, 109 and 165 were the most significant masses for this classification. Moreover, the chemical structure of these mass ions could be assigned to the reproducible pyrolytic degradation products from caffeine.

Chronic consumers of boiled coffee have elevated serum levels of lipoprotein(a).

Lipoprotein(a) consists of an LDL-particle attached to apolipoprotein(a), which is made by the liver. Diterpenes present in boiled coffee raise serum levels of LDL cholesterol and of the liver enzyme alanine aminotransferase in man. We investigated the association between intake of boiled coffee and serum levels of lipoprotein(a). Healthy Norwegians 40-42 years of age, who habitually consumed five or more cups of boiled coffee per day (n = 150) were compared with matched filter coffee consumers (n = 159) in a cross-sectional study, as part of the Norwegian National Health Screening in 1992. The median lipoprotein(a) level was 13.0 mg dL-1 (10th and 90th percentile: 2.5 and 75.0 mg dL-1, respectively) on boiled and 7.9 mg dL-1 (10th and 90th percentile: 1.9 and 62.5 mg dL-1, respectively) on filter coffee (P = 0.048). Means +/- SE were 25.8 +/- 2.4 mg dL-1 and 19.6 +/- 2.0 mg dL-1, respectively (P = 0.04). Although not statistically significant, subjects consuming nine or more cups of coffee per day had higher lipoprotein(a) levels than those drinking five to eight cups per day in both coffee groups. Chronic consumers of unfiltered, boiled coffee have higher serum levels of lipoprotein(a) than filter coffee drinkers.

Coffee consumption and risk of ischaemic heart disease--a settled issue?

Based on a meta-analysis, it was recently stated that there is no association between coffee consumption and the risk of coronary heart disease. Why then, have studies on the issue shown quite variable results? A prospective study was performed in the Copenhagen Male Study on 2975 men (53-74 years) without cardiovascular disease at baseline in 1985/1986. They were classified according to self-reported consumption of filter coffee. Some 147 men (5%) were coffee abstainers. Potential confounders were alcohol use, physical activity, smoking, serum cotinine, serum lipids, serum selenium, body mass index, blood pressure, Lewis blood group, hypertension, non-insulin-dependent diabetes mellitus and social class. The incidence of ischaemic heart disease (IHD) 1985/86-1991. Some 184 men had a first IHD event. There was no significant difference between those consuming 1-4, 5-8 or > or = 9 cups per day after controlling for confounders (P-value of trend test: 0.14). The crude incidence rates were 6.8, 6.7 and 4.6%, respectively; the adjusted rates were 6.8, 6.7 and 4.0%, respectively. Coffee consumption was significantly (P < 0.05) inversely correlated with serum selenium concentration (never previously described) and, positively or negatively, with a number of other potential risk factors: smoking, alcohol use, serum triglycerides, serum cholesterol, blood pressure, social class, body mass index, and serum selenium. In nonsmokers and smokers of only a small amount of tobacco, coffee consumption was associated with a lower risk of IHD (P < 0.05). We conclude that the association between coffee consumption and risk of IHD is conditioned by known risk factors correlated with use of coffee, which may partly explain the inconsistencies in the results of previous studies.

The ‘Ring Sign’: Is it a reliable indicator for cerebral spinal fluid?

To study the development of a ring sign when blood is mixed with various fluids. One drop of blood and one drop of either spinal fluid, saline, tap water, or rhinorrhea fluid were placed simultaneously on filter paper, and the specimens were examined after ten minutes for the development of a ring. A variety of filter paper agents were used, including standard laboratory filter paper, paper towels, coffee filters, and bed linens. All fluids, when mixed with blood, gave rise to a ring sign; blood alone did not. The type of filter paper did not affect the development of a ring. In this experimental setting, the ring or halo sign is reliable for detecting cerebrospinal fluids but is not exclusive for cerebrospinal fluid.

Boiled coffee does not increase serum cholesterol in gerbils and hamsters.

In contrast to drip filter coffee, boiled coffee increases the serum cholesterol level in man. To identify the substance(s) responsible for this effect, it is necessary to find an animal model sensitive to boiled coffee. In this study, three groups of 20 male gerbils and three groups of six male hamsters were fed a control diet or a control diet supplemented with either freeze-dried boiled coffee or freeze-dried filtered coffee. At the end of the 5-week feeding period serum cholesterol levels were not different in either species fed the different diets. These results suggest that these animal species are not sensitive to boiled coffee, or that the cholesterol-raising factor in boiled coffee is lost during the process of freeze-drying.

Ultraviolet spectroscopic studies and the prediction of the feathering of cream in filter coffees

SummaryCream feathering was studied in sixteen samples made from six brands of filter coffee. We have used a predictive rule, deduced from our studies of instant coffees, to determine the likelihood of feathering occurring in filter coffee samples upon the addition of coffee cream. The predictive rule makes use of 1,3,4,5-tetra-hydroxycyclohexane carboxylic acid-3-[(3,4) dihydroxycinnamate] (chlorogenic acid) concentration in the coffee, and the ratio of ultraviolet absorbances at 261 nm and 340 nm. We found good agreement between the predicted and observed behaviour of samples of filter coffee and conclude that the predictive rule is reliable for both instant and filter coffees. The effect of increased fat content in the cream was also studied.

Effect of a lipid-rich fraction from boiled coffee on serum cholesterol

Scandinavian-style boiled coffee, which raises serum cholesterol, was found to contain more lipid material than drip filter coffee, which does not. Ten volunteers consumed a lipid-enriched fraction from boiled coffee for six weeks: the supplement provided 77 g of water, 1·3 g of lipid, and 1·6 g of other solids per day. Serum cholesterol rose in every subject; the mean rise was 0·74 mmol/l after three weeks (range - 0·09 to 1·48 mmol/l) and 1 ·06 SD 0·37 mmol/l or 23% after six weeks (range 0·48 to 1·52 mmol/l). The increase was mainly due to low-density-lipoprotein cholesterol, which rose by 29%, but very-low-density lipoprotein cholesterol was also raised, as evidenced by a 55% rise in triglycerides. High-density-lipoprotein cholesterol was unchanged. After supplementation had ended, lipid levels returned to baseline. Boiled coffee thus contains a lipid that powerfully raises serum cholesterol.

Consumption of Boiled Coffee is Correlated with Serum Cholesterol in Finland

The association between coffee consumption and serum cholesterol concentration was studied in a cross-sectional epidemiological study among 5704 men and women in Finland. The mean serum cholesterol values of those consuming boiled coffee (24% of the subjects) was significantly higher than that of drinkers of filtered coffee (69% of the subjects) in both sexes after adjusting for age, body mass index, smoking, serum gamma-glutamyltransferase, index of saturated fat intake, and physical activity: in men 6.37 versus 6.02 mmol/l, in women 6.22 versus 5.84 mmol/l, both significant at p less than 0.001. A significant dose-dependent effect was observed between the consumption of boiled coffee both in men and in women. For filter coffee drinkers a weak coffee dose-cholesterol association was found only for women. The magnitude of the effect of boiled coffee, 0.3-0.4 mmol/l in serum cholesterol values, is in accordance with the results from controlled trials carried out among both hyper- and normocholesterolaemic subjects.

The effect of coffee on blood lipids and blood pressure. results from a Norwegian cross-sectional study, men and women, 40–42 years

The association between boiled and filter coffee consumption and levels of cholesterol, triglycerides and blood pressure was studied, including 14168 men and 14859 women. A total of 94% drank coffee, 55% of the men and 48% of the women drank more than 4 cups per day. The type of coffee consumed varied between the counties, from 11 to 49% boiled and 49 to 87% filter coffee. Serum cholesterol increased linearly with increasing coffee consumption, and most strongly for boiled coffee. Controlling for other variables gave, for boiled coffee, an 8% increase for men and 10% for women. For filter coffee drinkers the coffee dose-cholesterol association remained significant only for women. Triglycerides showed a negative association with coffee, significant after adjustment for other variables. This effect was stronger for filter than for boiled coffee in both sexes. For men and women drinking 1 cup of coffee or more, a significant negative association between both systolic and diastolic blood pressure and number of cups of filter coffee was found. The influence of high consumption of different coffee-types on death rate from coronary heart disease is discussed.