Recovery of bioactive compounds from tomato and onion peels through different extraction methods and their use in active coatings

Abstract Producing active edible coating from tomato and onion peel as a method of waste disposal can be a favorable option, aligning with one of the primary goals of the food industry. This study investigates the valorization of tomato and red onion peels through the development of active edible coatings for bread preservation. In a novel approach that avoids chemical solvents, four different extraction techniques—microwave-assisted extraction (MAE), ultrasonic-assisted extraction (UAE), room temperature extraction, and high-temperature extraction—were evaluated to determine the most effective method for recovering phenolic compounds and antioxidant activity. Among these, MAE at 270 W for 7 min produced the highest yield (286.42 mg GAE/g dry extract), demonstrating both time efficiency and extraction effectiveness. Extracts obtained through MAE were then incorporated into edible coatings and applied to bread cubes at three concentrations (10, 50, and 100 mg/100 mL). Over a 7-day storage period, treated bread samples were evaluated for pH, moisture, weight loss, texture, and color parameters. Results showed that coatings with higher extract concentrations significantly reduced moisture loss and pH increase, delaying bread staling. Sensory analysis revealed that although the flavor of red onion extract influenced overall acceptability at higher doses, the formulation containing 50 mg extract per 100 mL successfully balanced preservation efficacy and sensory quality. This research provides a sustainable and functional solution for food waste utilization while offering an effective strategy to extend bread shelf life through bioactive edible coatings.