Effects of Roasting Degree and Concentration of Ethiopian Coffee Extract on the Quality Characteristics of Yanggaeng

The present study evaluated the effects of Ethiopian coffee extract (E) on the physicochemical, antioxidant, textural, and sensory properties of Yanggaeng according to the roasting degree (light, medium, and dark) and extract concentration (0% for the control group [CON] and 2%, 4%, and 6% for each roasted coffee extract). The proximate composition varied significantly according to the roasting degree and E concentration, with dark-roasted samples generally showing higher moisture content, and L6 and M6 exhibiting higher carbohydrate content. Colorimetric analysis revealed that the addition of E decreased lightness while increasing redness, yellowness, and total color difference. The pH values increased in all extract-added samples compared with that of the CON group, whereas Brix values varied according to the roasting degree and extract concentration without showing a clear concentration-dependent trend. The total polyphenol content remained comparable to that of the CON group, while the DPPH radical scavenging activity increased significantly in the dark-roasted group, with D6 showing the highest activity. Textural properties, particularly hardness, gumminess, and chewiness, were modified after the addition of E, with responses differing depending on roasting degree and extract concentration, indicating changes in the measured texture profile of Yanggaeng. Sensory acceptance testing revealed significant effects of concentration and interaction on preferences for color, aroma, and chewiness, whereas overall acceptance was comparable to that of the CON in most formulations. These findings indicate that Ethiopian coffee extract has potential as an ingredient for coffee-infused Yanggaeng with modified visual, textural, aroma-related sensory, and radical-scavenging properties.