Microwave vacuum drying behaviour on quality of dried Piper betle leaf

Abstract

Herbs are mainly preserved by air drying. Air drying becomes inefficient in respect of energy consumption, drying time and dried product quality. In microwave vacuum drying, water boiling point inside product can be decreased, therefore, allowing product to be dried at a lower temperature. This will have less negative effect to the phytochemical components and indirectly to maintain the desired quality of dried material. Piper betle is one of the invaluable medicinal plants where its leaves have been used for many medicinal purposes such as ailments, infections and as a general tonic. Chief constituent of the leaves is the volatile oil. Betel oil contains two phenols: betelphenol (chavibetol) and chavico. During rainy season, betel leaf is perishable quickly. Drying is an essential approach to process betel leaf to avoid spoilage for further use with higher value addition. In our current study, the effect of microwave-vacuum drying technique on quality of P. betle leaves was evaluated. This research was conducted from 2018 to 2019 in the Scientific Laboratory of Can Tho University, Vietnam. Results clearly revealed that the raw P. betle leaves should be blanched in hot water at 100°C in 30 sec, primarily dried under convective dryer at 50°C in 4 h, deeply dried under microwave vacuum dryer in pressure of 400 mbar at 60°C within 10 min to get the final safety moisture content 8%. By this approach, the most phytochemical components such as total phenolic, flavonoid and tannin could be maintained in an effective manner. Microwave vacuum drying can save energy and preserve product quality of medicinal and aromatic plants in general and P. betle leaves in particular.