Changes in the physicochemical and antioxidant characteristics of watermelon during pekmez production

Abstract

Watermelon is a health-promoting fruit in terms of being an excellent source of lycopene and gastronomically pleasing. However, its consumption is restricted to a certain season because it is usually consumed as fresh. Therefore, utilisation of watermelon by processing into a more stable product that is available throughout the year would be beneficial. In this research, watermelon was utilised by processing into pekmez (concentrated juice) by concentrating the juice in open boilers until 68 degrees Brix, and changes in some physicochemical properties, colour and antioxidant characteristics that occur during pekmez production were determined. Sensory evaluations for pekmez products were also carried out. It was determined that the redness, yellowness, pH, titratable acidity and formol number values increase, whereas brightness, total sugar and invert sugar values decrease during processing the fruit into pekmez. Hydroxymethyl furfural was produced slightly during processing. Lycopene, total phenolic content and antioxidant activities of pekmez and juice were also compared. Although phenolic content was significantly (P<0.05) lower in pekmez samples, they exhibited significantly (P<0.05) higher antioxidant activity than the juice in terms of both 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and ferric reducing antioxidant power value.