This study evaluated the effects of Guatemalan coffee extract (G) on the physicochemical, antioxidant, and sensory properties of Yanggaeng at different roasting levels (light, medium, and dark) and concentrations (0%, control group [CON]; 2%, 2; 4%, 4; and 6%, 6). Moisture, ash, fat, protein, and carbohydrate contents varied significantly with G concentration and roasting level, with light roasts exhibiting the highest moisture and fat content, but the lowest ash and carbohydrate content. Colorimetric properties showed a dose-dependent decrease in lightness and an increase in redness and yellowness with the addition of G. Additionally, pH levels increased in light and dark roasts, but decreased in medium roasts, whereas Brix values increased with G, peaking in dark roasts. Antioxidant activity, assessed by total phenolic content and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, improved notably in the medium and dark roasts. Textural properties including hardness, resilience, and chewiness also benefited from the addition of G. Sensory evaluations favored Yanggaeng containing 4–6% G, especially in dark roasts, for attributes such as color, scent, and overall taste. Dark roast concentrations of 4% and 6% were identified as optimal for enhancing the properties of Yanggaeng, supporting the potential of G to develop innovative high-quality desserts tailored to modern consumer preferences.

This study examined the effects of alternative sweeteners—allulose, stevia, and xylose—on the physicochemical, textural, and sensory properties of Yanggaeng fortified with 2% Corni fructus powder (CF). A proximate composition analysis revealed that Yanggaeng treated with alternative sweeteners had a significantly higher moisture content and a lower carbohydrate content than that treated with sugar. Colorimetric analysis showed that the xylose treated Yanggaeng decreased lightness (L*) and increased redness (a*) and yellowness (b*), likely due to enhanced browning reactions. The xylose treated Yanggaeng exhibited the highest Brix values and antioxidant activities, including DPPH and ABTS radical scavenging and ferric reducing antioxidant power (FRAP). Although the allulose treated group had the highest total phenolic content, its radical scavenging activity was lower than the xylose treated Yanggaeng. Xylose produced a firmer and more cohesive gel matrix, increasing hardness, gumminess, and chewiness, whereas stevia resulted in a softer, less chewy texture. In sensory evaluations, the xylose treated Yanggaeng scored higher for color, flavor, sweetness, overall acceptance, and purchase intent than other groups. These findings suggest that xylose is the most suitable alternative sweetener for CF-enhanced Yanggaeng, offering reduced caloric content, enhanced antioxidant properties, improved texture, and superior consumer acceptance.