Sensory Characteristics of Espresso Coffee According to Green Coffee Processing

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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.

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Four different kinds of coffee beans (CS, Colombia supremo; EY, Ethiopia yirgacheffee; IM, Indonesia mandheling; and IMM, India monsooned malabar) were roasted at 200 and 250°C for 10, 15, and 20 min. To determine the optimum roasting conditions, various components of the coffee beans such as pyrazines produced during the roasting, and their antioxidant and antidiabetic effects were analyzed. The different roasting condition did not affect on the concentration of caffeine. However, the amount of 5-caffeoylquinic acid and the total phenolics decreased significantly, at a greater temperature and a longer roasting time. The greatest amount of pyrazines was produced from the IMM however, the amount of pyrazines decreased rapidly at 250°C according to increasing in roasting time. The DPPH free radical scavenging activity was mostly 80% more effective than that of BHT and α-tocopherol activities at the same concentration. In the case of the FRAP assay, the reducing power of the coffee slightly decreased at a greater temperature pand longer time. While the inhibitory effect on α-glucosidase was negligible, the activity decreased by more than 80% when the coffee beans were roasted at 250°C for 20 min. The inhibitory effect on α-amylase showed similar results. Taken together, the optimum roasting conditions were determined to be 200°C and 15 min, which provided the best physiological activity and nutty and chocolatey aromas from the pyrazine of coffee.
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.
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.
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.
Green coffees produced by three variants of the wet process and a new “ecological” process were characterised for their aroma using combined headspace solid-phase microextraction/gas chromatography–mass spectroscopy (HS-SPME/GC–MS) and headspace solid-phase microextraction/gas chromatography–olfactometry (HS-SPME/GC–O). The effect of each post-harvest processing operation on the volatile fraction of the coffee produced was studied, particularly the effect of reducing the amount of water used in the process. The comparison of the green coffees from the different treatments revealed the importance of mucilage removal in distinguishing between the samples, and showed the merits of microbial mucilage removal in water to obtain coffees with a better aroma quality. These latter coffees were in fact characterised by pleasant and fruity aromatic notes, whereas those obtained after mechanical mucilage removal used in the ecological process were characterised by volatile compounds with an unpleasant note.
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.
The magnitude and diversity of the microbial population associated with dry (natural) processing of coffee (Coffea arabica) has been assessed during a 2-year period on 15 different farms in the Sul de Minas region of Brazil. Peptone water-washed samples were taken of maturing cherries on trees (cherries, raisins and dried cherries) and from ground fermentations. The microbial load varied from 3×104 to 2.2×109 cfu/cherry with a median value of 1.6×107 cfu/cherry. The microbial load increased after heavy rainfall on cherries that were drying on the ground. At all stages, bacteria were usually the most abundant group, followed by filamentous fungi and finally yeasts. Counts of bacteria, yeasts and fungi varied considerably between farms and at different stages of maturation and processing and no consistent pattern could be seen. Yeasts showed an increase during the fermentation process. Median counts were not significantly different for fungi, yeasts and bacteria between the 2 years although Gram-negative bacteria dominated in the wet year and Gram-positive bacteria dominated in the dry year. Of a total of 754 isolates, 626 were identified to at least genus level comprising 44 genera and 64 different species. The 164 isolates of Gram-negative bacteria included 17 genera and 26 species, the most common of which were members of the genera Aeromonas, Pseudomonas, Enterobacter and Serratia. Of 191 isolates of Gram-positive bacteria, 23 were spore-forming and included six Bacillus species, and 118 were non-spore-formers of which over half were Cellulomonas with lesser numbers of Arthrobacter, Microbacterium, Brochothrix, Dermabacter and Lactobacillus. Of the 107 yeast isolates, 90 were identified into 12 genera and 24 different species and almost all were fermentative. The most common genera, in decreasing frequency, were Pichia, Candida, Arxula and Saccharomycopsis. There were many rarely described yeasts including Pichia lynferdii and Arxula adeninivorans. Almost all 292 fungal isolates were identified to genus level and 52 were identified to species level. Cladosporium, Fusarium and Penicillium each comprised about one third of the isolates and were found on all farms. Only 3% of the isolates were Aspergillus. Beauvaria, Monilia, Rhizoctonia and Arthrobotrys species were also occasionally found. The microbial flora is much more varied and complex than found in wet fermentations. The genera and species identified include members known to have all types of pectinase and cellulase activities.
Bacteria, yeasts and filamentous fungi were isolated during natural coffee processing. Bacteria were isolated in greater numbers at the beginning of the fermentation, when the moisture of the coffee beans was around 68%. Gram-positive bacteria represented 85.5% of all bacteria isolated, and Bacillus was the predominant genus (51%). Gram-negative species of the genera Serratia, Enterobacter and Acinetobacter were also found. Approximately 22% of 940 randomly chosen isolates of microorganisms were yeasts. Debaryomyces (27%), Pichia (18.9%) and Candida (8.0%) were the most commonly found genera, and these three genera tended to appear more often as the fruit was fermented and dried. Aspergillus was the most abundant genus besides Penicillium, Fusarium and Cladosporium, with 42.6% of the total fungi isolates. The genera and species identified included members known to have pectinase and cellulase activities. Of the 10 organic acids analyzed and quantified in coffee beans, acetic and lactic acids may have been generated by microbial activity. Butyric acid was not detected in any sample.
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