EFFECT OF SURFACE AREA AND TEMPERATURE ON DRYING CHARACTERISTICS OF BETEL LEAF (PIPER BETLE L.).

Betel leaf is the green gold of India for its food and medicinal values. In India, betel leaf is cultivated around 55,000 hectors of land encompassing about 20 lakhs Boroj and employing same number of agricultural families. But due to its perishability and short shelf life, 35-70% wastage takes place every year due to storage and transport, logistics. So, drying can be an effective tool to preserve the betel leaf for a long time period. Therefore, the aim of the study was to optimize the drying time as a function of leaf surface area and drying temperature as well as determine the changes in drying characteristics for changes in drying temperature and leaf surface areas. Piper betel leaf cultivated in Midnapore district, West Bengal, India, was considered as raw material for the study. The experiments were conducted at three range of temperature and leaf surface area. Temperature and leaf surface area both have a significant effect on drying rate and in decrement of total drying time (p<0.05). With increase in surface area of exposure and drying temperature the moisture diffusivity initially increases but later on decreases. Three drying mathematical models were applied and one response surface model was developed in this study. Wang & Singh model and response surface model both were found to be best (_p<0.05) for describing the drying kinetics. [ABSTRACT FROM AUTHOR]