Background: Plum (Prunus subg. Prunus) is a single-seeded fruit known for its variety in size, color, and flavor. During the processing of plums, a substantial amount of plum peel waste is generated. Objectives: This study investigates the potential of utilizing black plum peel, a by-product of plum processing, to create a new product: Black plum peel syrup. Methods: Black plum peel was collected from plum processing factories. The peel's chemical composition, antioxidant capacity, phenolic content, heavy metal levels, pesticide residues, and mold contamination were analyzed. Various formulations of black plum peel syrup were developed, with sensory evaluations used to determine the optimal formulation. The chemical properties, rheological characteristics, antioxidant activity, and phenolic content of the best formulation were then assessed. Results: Black plum peel was found to be rich in minerals and ascorbic acid, with high antioxidant activity and phenolic content. Heavy metals, including mercury, cadmium, and lead, as well as organophosphorus pesticide residues, were at negligible levels. The optimal formulation, containing 50% black plum peel and no added pectin, exhibited a Brix value of 73.25%, moisture content of 47.32%, acidity of 5.11%, and a pH of 2.93. Rheological measurements recorded the apparent viscosity, consistency coefficient, and Flow Behavior Index at 13.30 Pa.s, 5.79 Pa.sn, and 0.48, respectively. Antioxidant activity and phenolic content were measured at 10.92% and 0.66 mg/g GA, respectively. Conclusions: Black plum peel shows significant potential for syrup production. With its cooling and hydrating properties, black plum peel syrup is recommended as a refreshing beverage, particularly beneficial during the Arbaein pilgrimage for reducing body temperature, quenching thirst, and preventing dehydration.
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