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Sensory Characteristics of Espresso Coffee in Relation to the Classification of Green Arabica Coffee
Abstract
Arabica coffee has been classified for trading according to the New York Board of Trade (NYBOT) green coffee classification. The aim of the present study is to evaluate the physiochemical and sensorial characteristics of coffees classified by NYBOT as NY2 (specialty coffee), NY3/4 and NY4/5 (commercial coffee). The density of green coffee was higher for the NY2 sample. The amount of total solids in brewed coffee increase as the green coffee grade decreased and the pH levels decreased as the coffee grade decreased. Descriptive analysis using a 15cm line scale was carried out by 12 trained panelists prepared by espresso coffee and consumer preference tests were carried out by 168 consumers. The NY2 sample had the highest fruity, acidity, sweetness and aftertaste characteristics. In addition, green, rio, sour and astringency characteristics increased as the coffee grade decreased. Acceptance of aroma, flavor, taste balance and overall were higher for the NY2 sample. In the consumer preference test, the NY2 and NY4/5 samples had a similar distribution, but consumers between the ages of 20 to 30 who like to drink brewed coffee more than instant coffee preferred the NY2 than sample over the NY3/4 sample. In conclusion, significant differences were observed among the three groups of green coffee classification in all physicochemical and sensory parameters.
... For each cup for the straw samples, there was a clear plastic lid (Dart Container Corporation, Mason, MI, USA). Although samples were referred to as iced coffee, no ice cubes were added to prevent any dilution effects on the iced coffee beverage samples that have in fact been capable of impacting iced coffee perception (Choi & Yoon, 2010;Tekulsky, 2013). ...
A recent trend of environmental sustainability has induced many coffee providers to offer alternatives to plastic straws. There has been little research regarding consumer perception of these alternative drinking conditions. This study aimed to determine differences in consumer perception of iced coffee beverages (without ice cubes) between plastic straw and alternative drinking conditions. Brewed samples of medium roast ground coffee beans blend were cooled down and served at 5 °C in the five drinking conditions using different straw materials (plastic, paper, or stainless steel), sippy cup lid, or no lid. Seventy-five consumers rated attribute intensities and acceptances of iced coffee beverages in all five drinking conditions. The results showed that both the mean hedonic ratings of flavor, mouthfeel, or overall impression and the mean amount consumers were willing to pay (US$) for iced coffee beverages were greater in the sippy-cup lid condition than in the paper straw condition. After analyzing consumer comments of the drinking conditions, it was also found that the sippy-cup lid condition induced a more pleasant drinking experience than the paper straw condition. Notably, no significant differences between the plastic and alternative drinking conditions were observed in attribute intensity, acceptance, and monetary value perception of iced coffee beverages. In conclusion, this study shows that consumer experience and acceptability of iced coffee beverages can vary with drinking conditions. Therefore, the coffee industry and sensory professionals should consider not only sensory aspects of coffee, but also drinking conditions to improve consumer experience with coffee beverages.
The physicochemical characterstics of El Salvadoran Coffea arabica cv. Bourbon coffee extracts under various roasting conditions were investigated. Green beans were roasted under four different conditions (Light-medium, Medium, Moderately dark, and Very dark). The coffee extracts were prepared by using the espresso or drip methods. As the roasting degree increased, the coffee bean moisture content decreased and the ash content increased. The lightness and yellowness of the beans and coffee extracts decreased along with the increasing roasting degree. In the drip coffee, the reducing sugar content decreased and the pH value increased along with the increasing roasting degree. Both in the espresso and drip coffee, total organic acid and chlorogenic acid contents decreased, while the caffeine content increased along with the increasing roasting degree. Therefore, it is suggested that the roasting degree affects the physicochemical characteristics of coffee extracts.
Coffee beans are processed from coffee cherries by either natural, pulped natural, or washing. The aim of the present study was to evaluate the physiochemical and sensory characteristics of espresso coffees processed by different methods. The color of the washed coffee sample presented the highest value of lightness while the natural coffee sample presented the highest value of redness and yellowness. The biggest difference in brewed coffee, whether natural, pulped natural, or washed, was in the TDS content, which was higher in natural coffee and lower in washed coffee. Sensory descriptive analysis and acceptance test for espresso coffee using a 15 cm line scale were carried out by 12 trained panelists. Natural coffee had the highest cherry-like flavor and sweetness taste while washed coffee had the highest citrus flavor and acidity taste. An important attribute of espresso coffee is body, and natural coffee presented strong body while washed coffee presented a low body attribute. In conclusion, significant differences were observed among the three processing methods of green coffee. Pulped natural coffees presented intermediate physiochemical and sensory characteristics compared to washed and natural coffee. Natural coffees are appreciated for their increased body, and washed coffees are appreciated for added citrus flavors and acidity espresso coffee blends.
Grinding is an indispensible step in preparation of espresso coffee. The purpose of this study was to evaluate physicochemical and sensory characteristics of espresso according to the grinding grades of coffee beans. Specifically, physicochemical characteristics according to the grinding grades of coffee beans were tested based on foam index, persistence of foam, total solids, concentration, extraction yield, pH, viscosity, total soluble solid content and density. With regard to sensory characteristics, QDA were carried out by 10 trained panels. Persistence of foam, total solids, concentration, extraction, pH and viscosity in physicochemical test showed significant differences among the three categories of the samples. In other words, the finer the size of particles was, the higher value was, at the p=0.001 value. Meanwhile, the value of foam index and total soluble solid content to the grinding grades was the highest in 'fine', at the p=0.001 value. Tiger-skin effect in crema, an important attribute for excellent espresso coffee, was perceived by all of the panels in 'fine'. Also, intensity of flavor was perceived as to the strongest in 'fine'. Moreover, 'fine' had the sweetness to balance the acids and bitters. In conclusion, according to the grinding grades, it was identified that there were differences in the physicochemical and sensory characteristics. Furthermore, when the size of particles was 'fine', it brought to the most positive result.
This study aims to understand college students customer's preference and the difference of coffee grade by comparing the result of Q-grader, who was trained professionally and received certification for a sensory evaluation of coffee grade. The results of the chemical analysis of raw coffee and coffee berry show that those of specialty grade had slightly higher, but not significant, water content. Further, the pH of specialty grade coffee was high in coffee beans and after roasting, the commercial grade became high. There was no significant difference between the specialty degree and commercial degree in color before and after roasting. In this study, the panels for the sensory evaluation included 24 university students. The preference of evaluation items of sensory evaluation consist of aroma, acidity, bitterness, astringency, aftertaste, and overall satisfaction. Items for the strength evaluation consist of aroma, acidity and bitterness. The sensory evaluation was expressed by applying a 5 point Likert scale (1: extremely low~5: extremely high). In the sensory evaluation, it was evaluated that specialty grade coffee had strong acidity and commercial grade coffee was strongly bitter. The result of the sensory evaluation shows that female students are sensitive to coffee taste. In the analysis of frequent visit to coffee shop, the not-frequently-use-group rated that specialty grade coffee with higher overall satisfaction than commercial grade coffee in factors such as aroma and acidity. The group which did not prefer Americano coffee rated that specialty grade was higher than commercial grade in all factors except aroma, of which the result is similar to the cupping test.
To investigate the optimum ratio of sucrose replacement with high intensity sweeteners, the sensory characteristics and consumer acceptability of coffee drinks containing sucralose and acesulfame-K were studied using descriptive analysis and consumer testing. The relative sweetness of the sucralose and acesulfame-K to sucrose were 600-700 and 200-400 times greater, respectively, within the coffee drink system. The sucrose-replaced coffee drinks containing 100% sucralose, as well as mixtures of sucralose/acesulfame-K in ratios of 75/25 and 50/50, showed sensory profiles that were more similar to those of the original 100% sucrose coffee drink, which had a greater sweet taste, vegetable cream, caramel flavor, viscosity, and mouthcoating. These samples were not different from the 100% sucrose sample in terms of overall consumer acceptability.
Immature-black beans (VP) and immature beans (V), known by the Brazilian coffee terminology as ‘café verde-preto’ and ‘café verde’, are defective beans and cause a reduction of the quality of the beverage. Their presence in raw coffee samples is due to a high percentage of immature fruits at harvest. In this study, some of their physico-chemical properties and chemical composition were investigated and compared with non-defective coffee beans (B). B beans were heavier and had higher humidity than VP and V. Although they did not differ with respect to pH, V beans were more acidic (titrable acidity). Sucrose was the main soluble carbohydrate in all samples and its content in B beans was higher than defective beans. Reducing sugars were found at higher concentration in V and B beans. Protein contents increased from VP to B (VP<V<B); however, there was no relationship with free amino acid contents, which were higher in V beans. Qualitative analysis showed that asparagine was the main amino acid in these beans. Denaturing electrophorectic (SDS-PAGE) profiles of proteins did not show qualitative differences among the three coffee types. The contents of 5-caffeoylquinic acid (5CQA) and soluble phenols were also higher in V beans, and their ratio increased from VP to B (VP<V<B). In this order, the reversed-phase high-performance liquid chromatography profile at 280 nm of methanolic extracts prepared similarly showed, in general, a reduction of detected peak areas. Polyphenol oxidase activity was inversely associated with 5CQA contents, V beans showing the lowest activity. Similar caffeine contents were observed in the samples. Total oil content was higher in B beans. In addition, the defective beans were individually mixed with B beans in different proportions and analysed for some constituents. The results showed that, depending on the substance analysed, its content in the B beans is significantly affected. Although the influence of each component of the raw coffee bean that determines beverage quality has never been established, our results show that the presence of defective beans can drastically change the chemical composition of the final product.
Brazilian arabica coffee is classified for trading according to the quality of the beverage obtained after roasting and brewing. In the present study, Brazilian green and roasted coffee beans were investigated for possible correlations between cup quality and the levels of sucrose, caffeine, trigonelline and chlorogenic acids, determined by HPLC analysis. Trigonelline and 3,4-dicaffeoylquinic acid levels in green and roasted coffee correlated strongly with high quality. To a lesser extent, caffeine levels were also associated with good quality. On the other hand, the amount of defective beans, the levels of caffeoylquinic acids (predominantly 5-caffeoyilquinic acid), feruloylquinic acids, and their oxidation products were associated with poor cup quality and with the Rio-off-flavor. The fact that similar correlations between cup quality and chemical attributes were observed in green and light roasted samples – the latter used for coffee cup classification – indicates that chemical analysis of green beans may be used as an additional tool for coffee quality evaluation.
Arabica coffee is classified for trading according to the New York Board of Trade(NYBOT) green coffee classification. NYBOT's grading system is based on classification derived from a defect count on a 300 g sample. In the present study, green and roasted coffees were investigated for possible correlations between the content of defective beans and sensory characteristics. Sensory evaluation was performed by expert tasters used by the Specialty Coffee Association of America(SCAA) cupping method. For green coffee, the percentage of defective beans increased. as the coffee grade decreased. Black and sour beans were not found in the NY2 grade coffee out of all natural, pulped natural, and washed coffee samples. Sour and insect damage were found in more natural coffee samples as the green coffee grade decreased. Green and broken beans were found in more washed coffee samples as the green coffee grade decreased. Flavor, clean, uniformity, aftertaste, and overall sensory characteristics were significantly different among the NY2, NY3/4 and NY4/5 grade coffee in all natural, pulped natural and washed coffee samples. The natural coffee in the NY2 sample presented the highest body characteristic. The pulped natural coffee in the NY2 sample presented the highest sweetness and balance characteristics. The washed coffee in the NY2 sample presented the highest acidity and flavor characteristics. In conclusion, the percentage of defective beans increased as sensory characteristics decreased.
One of the most important criteria used for assessing coffee quality is based on sensory analysis and is referred to as cup quality. The presence of defective coffee beans is quite relevant to coffee quality. However, the majority of data on coffee properties are restricted to supposedly good quality beans. Therefore, the present study is aimed at an evaluation of physical and chemical attributes of coffees of different qualities, both green and roasted. Arabica coffee samples, previously classified by cup as soft (higher quality), hard, rioysh and rio (lower quality), were roasted at 200°C for 1h. Regarding attributes of green coffee beans, both bean density and volume were higher for the soft sample compared to the rio one. The soft sample also presented higher protein levels, due to its higher caffeine contents. The rio sample presented lower lipid contents, probably associated to the presence of defective beans. Acidity increased and pH levels decreased as cup quality decreased, probably due to the effect of defective beans that undergone fermentation (sour beans). After roasting, the rio sample presented higher density and trigonelline levels, indicating that it did not roast to the same degree as the other samples.
Grading systems since their conception have aimed at facilitating commercialisation of food stuff world-wide. However, while many food products can have their quality assessed by analytical means, there are many foods that are sold according to their sensory quality and for which quality is not easily measured by conventional analytical techniques. Measuring sensory quality in some products has moved forward and utilises fully trained panels to set-up quality control systems and routine evaluations while others still rely on traditional commercial classifications and grading systems. The grading discussed here must be differentiated from grading using “trained experts” to evaluate food products according to legislated standards. There are specific cases in which the need to comply with national or international standards requires the development of specially trained tasting experts. Bisogni, Ryan, and Regenstein (1987) [In D. E. Kramer, & J. Liston (Eds.), Seafood quality determination (p. 547). Amsterdam: Elsevier Science] illustrates quite well this specific scenario. The case of coffee, the most traded agricultural crop world-wide is examined here. In coffee a high diversity of classification systems is applied and the use of the “expert cupper” is the norm. There is not a unique and universal system applied world-wide for the quality control of green coffee. Tailor made procedures are selectively implemented by International, National, local bodies, trading institutions and private companies. Procedures are mostly geared to facilitate the trading of the commodity and sensory quality is in most cases described by “cuppers” or “liquorers” using personal opinion and tasting experience accumulated over the years.
Three espresso coffee (EC) samples of different botanical varieties and types of roast were prepared in standard conditions using an experimental EC prototype: Arabica coffee, Robusta Natural blend, and Robusta Torrefacto blend (a special roast by adding sugar). The ECs were characterized with regard to the physical parameters, amount of total solids, total solids on filtrate, lipids, caffeine, trigonelline, and chlorogenic acids by HPLC, and sensory descriptive analysis related to foam appearance, taste, and mouthfeel. Principal component analysis (PCA) was applied to differentiate the EC samples. Arabica and Robusta samples were separated successfully by principal component 1 (55.3% of variance) including physicochemical and sensory parameters related to foam and taste of ECs. Torrefacto and Robusta Natural EC samples were separated by principal component 2 (20.7% of total variance) including mouthfeel and other attributes of color foam. Some interesting correlations among sensory and physicochemical variables were found. A very simple discriminate function was obtained by discriminate analysis allowing the classification of each EC sample into its respective group with a success rate of 100%.
Water pressure is one of the most important factors which influence the final quality of espresso coffee (EC). However, few studies dealing with this issue have been found. The aim of this work was to study the effect of water pressure on the final quality of Arabica ECs as well as to classify ECs prepared at different pressures (7, 9, and 11 atm) according to their physicochemical and sensory characteristics, key odorants, by means of multivariate analysis. Statistically, principal component 1 (PC1) separated ECs prepared at 7 and 9 atm from ECs prepared at 11 atm and included the main foam and taste characteristics as well as some key odorants and flavor compounds. ECs prepared at 7 and 9 atm were separated by principal component 2 (PC2). Coffees prepared at 9 atm showed consistency of foam and a high percentage of key odorants related to freshness and fruity, malty, and buttery flavors. A simple discriminate function was obtained by discriminate analysis, allowing the classification of ECs prepared at three pressures into their respective groups with a success rate of 100%.
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Sensory properties and consumer acceptability of coffee drinks contained surculose and acesulfame-K
- Switzerland Kim
- K O Kim
- H Lee
- H S Shin
ISO(International Standardization Organization). 2004. Green coffeedefect reference chart. ISO 10470/2004. Prepared by Technical Committee ISO/TC 34, Agricultural food products.
Switzerland
Kim KO, Kim H, Lee HS, Shin JY. 2007. Sensory properties and
consumer acceptability of coffee drinks contained surculose
and acesulfame-K. Korean J. Food Sci. Technol. 39(5):527-533