Coffee is one of the most well-known favorite foods which has been enjoyed by the entire world over its long history and contains bitter tastes, astringency, acidic tastes, and goso flavors. The raw material for the coffee consumed in South Korea, the...
Coffee is one of the most well-known favorite foods which has been enjoyed by the entire world over its long history and contains bitter tastes, astringency, acidic tastes, and goso flavors. The raw material for the coffee consumed in South Korea, the green coffee beans and the roasted coffee beans are entirely dependent on the importation. As the consumption of the coffee increases, the importation volume of such materials is increasing continuously as well. As the consumption of coffee and other beverages increase, the consumers are seeking newer and more diverse choices, while preferring to healthy food products in consideration of the health and the quality of life. For this, it became necessary to develop new beverages that could meet such demands.
For this reason, the researcher conducted this study with a view to establishing the roasting condition for the optimized antioxidant activities of the whole adlay and dried citrus peel, which are South Korean specialty agricultural products and conducted a customer survey on the coffee containing these ingredients, to explore the possibility of developing a mixed coffee product that could meet both serve the functional and preferential demands.
In Part Ⅰ. of this study, the RSM(Response Surface Methodology) was used on the whole adlay and dried citrus peel to establish the roasting condition that could maximize the antioxidant activities. The independent variables of the study were the temperature(X1)and time(X2), which were divided into 13 segments based on the core synthesis plan. After the extraction of the ingredients in hot water, the electron donating ability, total phenolic compound content, total flavonoid content, and hydroxyl radical scavenging activity were analyzed. The result of the analysis showed that the optimal roasting condition for the maximized antioxidant effect was 178.00℃, 9.97 min for the whole adlay and 70.90℃, 9.03 min for the dried citrus peel.
In Part Ⅱ, a customer survey and the sensory evaluation were conducted on the coffee containing the whole adlay and the dried citrus peel. Firstly, the whole adlay which was processed under the optimal roasting conditions was added in 5%, 10%, 15%, 20%, and 25% in a blended coffee base composed of coffee beans from Brazil, Sumatra Mandheling, Doi Chang of Thailand, and beans for Ethiopia, so that the flavors of the roasted whole adlay can harmonize with the flavor of the coffee. The dried citrus peel was also roasted under the optimal conditions and was added in 5%, 10%, 15%, 20%, and 25% to the blended coffee base composed of Yirgacheffe and Sidamo, in consideration of the harmonization of the flavors. These sensory attributes of these samples were evaluated and the result showed 26 characteristics, included the nut taste, cacao taste, goso taste, herbal medicine taste, goso flavor, herbal medicine flavor, bitterness, savory taste, and heavy body taste. The analysis on the correlations between the characteristics showed that the goso taste was closely and positively related to the nut flavor and the nut flavor was positively related to the cacao flavor and the strength of the coffee. On the other hand, the acidic flavor was positively related to the herbal medicine flavor and herbal medicine taste, while negatively related to the goso taste and cacao taste.
The PCA(Principal Component Analysis) of the sensory attributes showed that the overall strength of the taste, savory taste, bad smell, acidic taste, food additive taste/flavor, acidic flavor, herbal medicine flavor, and soil flavor were strongly loaded to the positive direction of the primary component. Especially, the sample with 25% dried citrus peel showed the strongest characteristics. The bitter taste, strength, nut flavor/taste, goso flavor, and sweet flavor were strongly loaded to the negative direction of the primary ingredients. In consideration of the positions of the samples, it was determined that these were the commonly existing characteristics in the coffee samples with whole adlay.
The customer survey was conducted with a sample group of 90 participants, composed of 15 male and 15 female participants, respectively, from each age group of 20s, 30s, and 40s. The participants were presented with the whole adlay and dried citrus peel coffee samples of different proportions. The survey was conducted as a CATA(check-all-that-apply) method on the preference and the cause of preference or non-preference of the whole adlay and dried citrus peel coffee samples. The result of the survey on the preference showed that the participants in their 20s generally preferred 5% whole adlay samples, while 30s 10% and 40s 15%. As for the dried citrus peel coffee samples, all age groups showed a high preference to the 5% samples as a whole.
In the CATA survey, the common preferential factors of the whole adlay coffee were the color, goso flavor, burnt flavor, and familiarity and the non-preferential factors were the astringency and bitterness. The common preferential factors of the dried citrus peel coffee samples were the light body taste, smooth swallowing and color, while the non-preferential factors were the acidic taste, and unfamiliarity/strangeness. Also, as the density of the dried citrus peel increased, the frequency of selecting the acidic taste, acidic flavor, strangeness, and herbal medicine flavor as the non-preferential factors increased in all age groups, while the frequency of selecting the uniqueness and impression that the beverage might be good for health as the preferential factors increased.
In this study, the possibility of using the whole adlay and the dried citrus peel as a health food material was explored and the optimal conditions for using them were established, while it was confirmed that the age groups and the density of these ingredients affected the level of preference. It is expected that the findings in this study could be used in the development of the healthy, functional coffee beverage for different age groups.