Drip Coffee Research Articles

Characterization of Headspace Aroma Compounds of Freshly Brewed Arabica Coffees and Studies on a Characteristic Aroma Compound of Ethiopian Coffee

A sampling method to isolate headspace volatiles of freshly brewed drip coffee using a solid-phase microextraction fiber (fiber type: divinylbenzene/carboxen/polydimethylsiloxane) in a short time (2 min) immediately after extraction has been developed. Volatile compounds and potent odorants obtained from each headspace aroma of various arabica coffee extracts (3 production countries: Ethiopia, Tanzania, and Guatemala; 3 roasting degrees for each country: L26, L23, and L18) using the sampling method were examined by gas chromatography/mass spectrometry (GC/MS) and GC/olfactometry (GC/O, CharmAnalysis). The results of principal component analysis (PCA) using the data of GC/O analysis showed that the aroma profile of Ethiopian coffee was discriminately different from those of Tanzanian coffee and Guatemalan coffee. In addition, it was suggested from the factor loading of the PCA that 4-(4'-hydroxyphenyl)-2-butanone (raspberry ketone; sweet-fruity odor) characterized the aroma profile of freshly brewed Ethiopian coffee. Therefore, the 4-(4'-hydroxyphenyl)-2-butanone was quantified in the 9 kinds of coffee extracts. Ethiopian coffee extract of the lightly roasted degree (roasting degree: L26) contained the highest amount of this component, while it was only a little over the reported threshold. In the sensory test, the headspace aromas of Tanzanian and Guatemalan coffees in which 4-(4'-hydroxyphenyl)-2-butanone was added were, respectively, discriminated from not added samples, and "sweet" odor was selected as an odor description that assessors found similarity between the added Tanzanian or Guatemalan coffee aroma and the Ethiopian coffee aroma. It was suggested that 4-(4'-hydroxyphenyl)-2-butanone made some detectable change on total aroma profile even though the added amount was only near threshold level.

Analysis of the Headspace Volatiles of Freshly Brewed Arabica Coffee Using Solid‐Phase Microextraction

Headspace volatiles of freshly brewed drip coffee were investigated by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/olfactometry (GC/O, CharmAnalysis) analyses. For this purpose, a solid-phase microextraction (SPME) sampling method for the headspace volatiles of freshly brewed drip coffee was developed. SPME fiber coated with divinylbenzene (DVB)/carboxen/polydimethylsiloxane (PDMS) was selected from 6 types, and sampling time was determined at 2 min. The headspace coffee volatiles stayed constant in proportion for the first 2 min to keep the freshness of the brewed coffee aroma. Using this sampling method, the headspace volatiles of freshly brewed drip coffee (Ethiopian arabica coffee, roast degree: L value; 23) were examined by GC/MS and GC/O analyses. From the GC/O results, 1-(3,4-dihydro-2H-pyrrol-2-yl)-ethanone (nutty-roast odor) and 4-(4'-hydroxyphenyl)-2-butanone (raspberry ketone, sweet-fruity odor) were newly detected as components in the aroma of coffee.

A structural component-based approach for designing product family

This study presents a novel approach for establishing an intelligent support system in order to design a product family through managing variety. Two approaches are applied successively. First, the Quality Function Deployment (QFD) approach identifies the exterior drivers of design variation. Second, the Interpretive Structural Model (ISM) technique is applied to visualize the hierarchy of component interactions within a product. This approach represents the design priority and related design constraints within a product using a structural graph, helping designers to create variant design solutions in a product family for different market requests. The methodology proposed here is illustrated via the example of the design of a family of automatic drip coffee makers.

It takes the whole brain to make a cup of coffee: the neuropsychology of naturalistic actions involving technical devices

Left hemisphere dominance has been established for use of single familiar tools and tool/object pairs, but everyday action in natural environment frequently affords multi-step actions with more or less novel technical devices. One purpose of our study was to find out whether left hemisphere dominance extends to such naturalistic action. Another aim was to analyze the cognitive components contributing to success or failure. Patients with LBD and aphasia, patients with RBD, and healthy controls were examined on experimental tests assessing retrieval of functional knowledge from semantic memory, inference of function from structure, and solution of mechanical and non-mechanical multi-step problems, and were confronted with two naturalistic tasks involving technical devices: preparing coffee with a drip coffee maker and fixing a cassette recorder. Both patient groups were about equally impaired on both naturalistic actions. Analysis of the experimental tests and their correlations to naturalistic actions suggested that different cognitive deficits caused failure in both patient groups, and that in LBD patients there were also different causes for failure on both naturalistic actions. The main difficulty of RBD patients seemed to reside in the demand to keep track of multi-step actions. In aphasic LBD patients difficulties with making coffee but not the cassette recorder were correlated with aphasia and defective retrieval of functional knowledge from semantic memory, whereas the cassette recorder correlated more strongly with a test probing solution of multi-step mechanical problems. Inference of function from structure which had been shown to be important for use of single familiar tools or tool/objects pairs [Goldenberg, G., Hagmann, S. (1998). AT Tool use and mechanical problem solving in apraxia. Neuropsychologia, 36, 581–589] appeared to play only a subordinate role for naturalistic actions involving technical devices.

Removal of soluble Cu and Pb by the automatic drip coffee brewing process: Application to risk assessment

Three commercial brands of coffee were examined for sorption of Cu and Pb. We kept experimental conditions close to those in ordinary situations by using an automatic drip coffee maker. One‐liter increments of de‐ionized water spiked with increasing amounts of Cu and Pb were used to make pots of coffee. Influent (water) metal concentration was then compared with effluent (coffee) metal concentration. We kept influent metal concentrations in ranges that might be expected due to contamination from storage tanks and pipes in municipal water delivery systems (0.1 to 5.0 mg/L). The coffee brewing process removed 78 to 90% of both Cu and Pb from influent water. We ran experiments by varying coffee strength (function of bed depth) and varying brewed coffee volume (function of bed depth and water volume) . Most of the metal that goes through the coffee bed does so in the early stages of the brewing process before the coffee bed is wetted. The main factor influencing removal of soluble metal by coffee is contact time with the wetted coffee bed. Therefore, the strength and/or volume of coffee brewed play a critical role in metal removal. Preliminary work with steeping teabags in metal spiked water showed little to no reduction in the soluble Cu and Pb concentration. Results of this study are important for risk assessment model formulations. Daily human exposure to Cu and Pb from municipal water systems may be grossly overestimated if a large proportion of tapwater ingestion by an individual is filtered through coffee.

Toxicological and biochemical effects of different beverages on human intestinal cells

The objective of the present study was to examine and compare the effects of frequently consumed beverages on the human intestinal cell line, Caco-2, in terms of toxicity, growth, and differentiation. For this purpose, Caco-2 cells were incubated for 24 h in the presence of: a mineral water, fresh orange juice, packaged orange juice, a cola drink, an energy drink, black, camomille, and green teas, and drip coffee. Toxicity was evaluated firstly by measuring the lactate dehydrogenase leakage from the cells and secondly by performing the MTT assay. Cell differentiation was determined by measuring two brush border membrane enzyme activities. Growth rates of Caco-2 cells were evaluated by cell counting. The results indicated that there were no significant differences between the beverages in toxicity and cell proliferation. Cells exposed to fresh orange juice exhibited higher tetrazolium reduction rates in the MTT assay (121.3% of control). These cells also showed higher succinate cytochrome c reductase activities than the other samples, implying that the contents of fresh orange juice, such as ascorbic acid, stimulated mitochondrial metabolism. The alkaline phosphatase and aminopeptidase N activities of the Caco-2 cells lay between 61.50 and 110.00%, indicating a partial influence of some beverages on Caco-2 differentiation.

Caffeine intake and low birth weight: a population-based case-control study.

The authors conducted a matched case-control study to investigate the effects of caffeine intake during pregnancy on birth weight. From January to November 1992, in the first 24 hours after delivery, 1,205 mothers (401 cases and 804 controls) were interviewed and their newborns were examined to assess birth weight and gestational age by means of the method of Capurro et al. (J Pediatr 1978;93:120-2). The cases were children with birth weight < 2,500 g and gestational age > or = 28 weeks. Cases and controls were matched for time of birth and hospital of delivery and were recruited from the four maternity hospitals in Pelotas, southern Brazil. Daily maternal caffeine intake during pregnancy for each trimester was estimated. To assess caffeine intake, 10% of the mothers were reinterviewed at their households and samples of reported information on drip coffee and maté (a caffeine-containing drink widely used in South America) were collected and sent to the laboratory for caffeine determination through liquid chromatography. When instant coffee was reported, the weight of powder was measured using a portable scale, and caffeine intake was estimated from a reference table. Caffeine intake from tea, chocolate, soft drinks, and medicines was estimated from a reference table. Analyses were performed by conditional logistic regression. Crude analyses showed no effect of caffeine on low birth weight, preterm births or intrauterine growth retardation. The results did not change after allowing for confounders.

Assessing the Importance of Design Through Product Archaeology

This paper assesses the importance of design in determining product costs by measuring the variation in design performance among a set of competing design efforts. This assessment is completed for a set of functionally similar products in a single product category: automatic drip coffee makers. The approach of this study is to measure the manufacturing content—the attributes of the design that drive cost—through analysis of the physical products themselves, and to estimate how variation in manufacturing content relates to variation in cost in a hypothetical manufacturing setting. We call this approach product archaeology. For the domain of coffee makers, we find significant variation in manufacturing content. This variation in manufacturing content corresponds to a range of estimated manufacturing costs, for a hypothetical manufacturing system, of approximately 50 percent of the average manufacturing cost of the products. We also find that differences in capabilities among product development efforts are the most plausible explanation for the differences in manufacturing content.

When Liquids Stay Dry

If you are in the habit of watching your drip coffee maker prepare your morning beverage, you'll occasionally witness something interesting: As the coffee drips into the pot, you'll often see one of the drops land on the surface and remain intact for a second or so before coalescing with the bulk liquid. This temporary noncoalescence of two bodies of the same liquid is neither an isolated phenomenon nor one that has been observed only in the era of drip coffee makers. As early as 1879, Lord Rayleigh examined how water jets bounce over each other, and in 1881 Osborne Reynolds observed what he called floating drops. (See the box on page 40.) A century later, “a scientific curiosity” was how Jearl Walker referred to the phenomenon.

Caffeine intake in relation to the risk of primary cardiac arrest.

We conducted a population-based case-control study in King County, WA, to evaluate the association between usual caffeine intake and primary cardiac arrest. We identified primary cardiac arrest cases (N = 362) without a history of clinical heart disease or major comorbidity through paramedic incident reports during the period 1988-1994. We identified controls (N = 581), individually matched to cases on age (+/-7 years) and gender and meeting the same general health criteria, through random digit dialing. We interviewed the spouses of cases and controls to obtain information on usual caffeine intake from coffee, tea, and cola during the prior year. After adjusting for cigarette smoking and other risk factors, we observed little association between daily consumption of the caffeine equivalent of fewer than 5 cups per day of drip coffee (< 687 mg per day) and primary cardiac arrest. High usual caffeine consumption (> or = 687 mg per day) was associated with a modestly elevated risk of primary cardiac arrest [odds ratio = 1.44; 95% confidence interval (CI) = 0.82-2.53]. The elevated risk associated with high caffeine consumption appeared to be restricted to never-smokers (odds ratio for > or = 687 mg per day = 3.2; 95% CI = 1.3-8.1).

Effect of coffee drinking on cell proliferation in rat urinary bladder epithelium

A possible effect of freshly brewed drip coffee on urinary bladder carcinogenesis was investigated in male Wistar rats using cell proliferation in urinary bladder epithelium as the indicator of tumour promotion. Male rats were given either undiluted coffee brew (100% coffee), coffee diluted 10 times (10% coffee) or tap water (controls), as their only source of drinking fluid for 2 or 6 wk. Uracil, known to induce cell proliferation in urinary bladder epithelium, was included in the study as a positive control. In rats receiving 100% coffee, body weights, liquid intake and urinary volume were decreased. Neither histopathological examination of urinary bladder tissue nor the bromodeoxyuridine labelling index revealed biologically significant differences between rats receiving coffee and the tap water controls. Uracil increased the labelling index and induced hyperplasia of the urinary bladder epithelium, as expected. It was concluded that these results produced no evidence that drinking coffee predisposes to tumour development in the urinary bladder.

Two Views of My Grandmother

Two Views of My Grandmother

Inhibition of food iron absorption by coffee

Dual isotope studies were performed in iron replete human subjects to evaluate the effect of coffee on nonheme iron absorption. A cup of coffee reduced iron absorption from a hamburger meal by 39% as compared to a 64% decrease with tea, which is known to be a potent inhibitor of iron absorption. When a cup of drip coffee or instant coffee was ingested with a meal composed of semipurified ingredients, absorption was reduced from 5.88% to 1.64 and 0.97%, respectively, and when the strength of the instant coffee was doubled, percentage iron absorption fell to 0.53%. No decrease in iron absorption occurred when coffee was consumed 1 h before a meal, but the same degree of inhibition as with simultaneous ingestion was seen when coffee was taken 1 h later. In tests containing no food items, iron absorption from NaFeEDTA was diminished to the same extent as that from ferric chloride when each was added to a cup of coffee. These studies demonstrate that coffee inhibits iron absorption in a concentration-dependent fashion.

Best bits: Applications of microprocessors: Chip makes drip coffee

Best bits: Applications of microprocessors: Chip makes drip coffee