Development of Kombucha Beverage from Kale Trimming Residues for Elderly Consumers

Abstract

Agricultural production often generates trimming residues, particularly from leafy vegetables that still retain high nutritional value but are not fully utilized. Kale is a nutrient-rich leafy vegetable containing vitamins, minerals, and various phytochemicals. However, commercial grading processes result in a substantial amount of trimming waste. This study aimed to develop a kombucha beverage using kale trimming residues and to investigate the incorporation of local ingredients, including ginger, mango, and tamarind. Physical, chemical, and microbiological qualities, as well as sensory acceptance among elderly consumers, were evaluated. Five formulations were prepared: a black tea control (Formula 1) and kale-based formulations incorporating local ingredients (Formulas 2–5). Fermentation was conducted using a commercial symbiotic culture of bacteria and yeast (SCOBY) at an initial volume of 500 mL at an ambient temperature of approximately 25 – 30 °C for 30 days. Sensory evaluation was carried out with 50 elderly participants (≥60 years old) using a 9-point hedonic scale. The results indicated that the 100% kale formulation (Formula 2) received significantly higher scores in color and overall acceptability compared with other formulations (p < 0.05). The color parameters (L*, a*, b*) were 42.51, 1.41, and 6.60, respectively. The pH values ranged from 2.51 to 3.53, and total soluble solids ranged from 2.6 to 8.0 °Brix, with no significant differences among formulations (p > 0.05). No pathogenic microorganisms were detected, and the safety parameters complied with relevant standards. These findings demonstrate that kale trimming residues can be effectively utilized to develop a high-quality kombucha beverage acceptable to elderly consumers, while contributing to agricultural waste valorization and sustainable resource utilization.