Effects of drying conditions on physicochemical and antioxidant properties of banana (Musa cavendish) peels

ABSTRACT

A significant amount of banana peels is generated as waste annually and shows great potential as a lead material for further utilization in the nutraceutical industry. However, potentiality of banana peel utilization largely depends on the favorable drying condition of the material before it can be used for further processing. Therefore, it is necessary to identify the suitable drying conditions for banana peel. This study investigated the effect of six different drying methods on the quality of banana peels. The results showed that different drying conditions significantly affected the physical, chemical, and antioxidant properties of dried peels. Microwave irradiation at the power level of 960 W for 6 min was the most suitable condition, as these dried peels had good physical properties, minimum loss of bioactive compounds, and antioxidant properties. This was followed by freeze-drying, vacuum oven at 60°C, hot air oven at 120°C, dehumidified air at 60°C, and sun drying. The peels dried by microwave possessed a total phenolic content of 25.26 mg of gallic acid equivalents/g of dry matter (DM) and potent antioxidant capacity [(1,1-diphenyl-2-picrylhydrazyl) of 37.70; 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid of 46.35; ferric reducing antioxidant power of 45.94; and cupric ion reducing antioxidant capacity of 64.55 mg of trolox equivalents/g of DM]. Therefore, the study recommends the use of microwave irradiation under the studied condition (power level of 960 W for 6 min) for further processing and utilization.

KEYWORDS:

• Antioxidants
• banana
• drying
• peel
• phenolic

Acknowledgments

The awarding of a VIED-TUIT scholarship to the Hang T. Vu is greatly acknowledged. The first authors would like to thank Dr. Dipangkar Kundu (The University of Sydney) for valuable statistical advices, and Ms. Hong Ngoc Thuy Pham (The University of Newcastle) for her assistant in laboratory work. Associate Editor Dr. Sakamon Devahastin, and anonymous referees are acknowledged for providing insightful reviews of the manuscript, which improve the quality of the manuscript.