Effects of Adding of Tomato (Lycopersicon esculentum Mill.) Peel Powder on Quality Characteristics of Yanggaeng

This study aimed to evaluate the potential use of tomato (Lycopersicon esculentum Mill.) peel, which is typically discarded during food processing, as a functional food ingredient. The peel was dried and powdered for incorporation into Yanggaeng, a traditional Korean sweet red bean jelly. The tomato peel extract contained 31.29±1.92 μg/g of lycopene, a concentration comparable to that of tomato pulp extract (33.10±1.46 μg/g). Notably, the total flavonoid content of the tomato peel extract (1,183.33±48.75 μg/g) was significantly higher than that of the pulp extract (603.57±54.05 μg/g), and its DPPH radical scavenging activity was also superior, showing a positive correlation with flavonoid content. For the preparation of Yanggaeng, tomato peel powder was added at levels of 0%, 1%, 2%, 3%, and 4% relative to the weight of white bean paste. As the concentration of tomato peel powder increased, moisture content decreased. Color analysis revealed a reduction in L* value and increases in a* and b* values with higher levels of tomato peel powder. Texture profile analysis showed proportional increases in hardness, adhesiveness, cohesiveness, gumminess, springiness, and chewiness. Sensory evaluation indicated that the Yanggaeng sample containing 3% tomato peel powder received the highest scores in color, aroma, taste, appearance, texture, and overall acceptability, with an overall preference score of 4.59 compared to 2.18 for the control. Additionally, the flavonoid content of Yanggaeng with 3% tomato peel powder sample was 401.42±80.88 μg/g, more than twice that of the control (193.64±102.88 μg/g).