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Dragon fruit ( Hylocereus polyrhizus) peel is high in antioxidants and fiber; however, it is discarded during processing. In this study, changes in physico-chemical properties of dragon fruit peel after drum drying were determined. Ground dragon fruit peel was drum dried at 1 rpm with 2 bar steam pressure, then analyzed for physical, chemical and functional properties. The betacyanin content was twofold higher in drum-dried powder (41.55 mg/g dm) than in a fresh sample (80.21 mg/g dm), yet up to 98.62% of the total phenolic content was retained with a 3.328 mg trolox/g dm reduction in the radical scavenging activity. The density of the powder was 0.1315 g/mL with 51.44% soluble in water. The functional properties determined included water holding capacity (2.523 g water/g sample), oil holding capacity (3.565 g oil/g sample) and swelling capacity (6.233 mL/g). The results of this study indicate that drum-dried dragon fruit peel can be considered to contain potentially functional ingredients. [ABSTRACT FROM AUTHOR]

Abstract: Typically, banana trees are cut once the fruit has been harvested; however, other parts of the banana tree, particularly the leaves, might have other potential uses. Nevertheless, few studies have focused on banana leaves. This work aims to provide information about the effects of different drying temperatures on the antioxidant activity, total phenolic content and physical properties of banana leaves (Musa acuminata Colla (AAA Group)). Leaves were dried at different temperatures (40°C, 50°C or 60°C) using a cabinet dryer with an airflow of 2m/s. Dried and fresh leaves were analysed for their moisture content, water activity, pH, colour analysis and rehydration index. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Folin–Ciocalteau methods were used to determine the scavenging activity (IC50) and total phenolic content of the fresh and dried leaves extracts, respectively. The results reveal that the drying temperature significantly affects selected properties of banana leaves and 50°C is proposed as the appropriate drying temperature. [Copyright &y& Elsevier]