Comparative Study of the Pyramid-Shaped Tunnel and Cabinet Dryer for Drying Coriander Leaves

Coriander is an integral part of South Asian cuisine and it is one of the most consumed leafy vegetables in south Asia. It is also a rich source of minerals and proteins. The delicate nature and low shelf-life lead to a high amount of wastage which can be avoided by drying. Solar drying is an efficient and economically justifiable method for drying coriander leaves. In the present work, PSTD and PSCD solar dryers are used for drying coriander leaves and the performance of these dryers at 0.5 m/s air velocity is monitored. During the experimental day, the ambient temperature ranged between 34 to 42 0C, and solar radiations varied between 584 w/m2 (Minimum) and 996 w/m2 (Maximum). The average air temperature inside the dryer chamber of both dryers is recorded as 10-150 C higher than the ambient temperature. The experimental results show that the drying time of coriander leaves can be significantly reduced by using the solar dryer. The developed PSTD outperforms the PSCD in terms of drying time, moisture reduction rate, instantaneous drying rate, and drying efficiency. The nutritional analysis tests of coriander leave before and after drying show that the quantitative retention of nutrients like total minerals, crude protein, crude fat, crude fiber, carbohydrates, and total energy is more in samples dried in a PSTD as compared to a PSCD. Nutritive tests also indicate that the drying process and type of dryer do not have a significant effect on the nutritional content of coriander leaves.