Qualitative study of fragile agricultural products using hybrid solar dryer

Plants are main sources of food and income. Post-harvest losses and. spoilage of plants changes the quality and reduces the quantity of products. Preservation of food is required to reduce decay, to increase the time for availability, to maintain the required characteristics of nutrition for long period of time and to produce value added products. Different methods could be used to preserve food. Drying needs large amount of heat to remove water to preserve the products. Natural sun drying is the most common method of drying. The major restriction of using this method is that the product undergoes unwanted changes due to high temperature. The products needs be dried at low temperature but it increases the drying cost. Also, the conventional fuel prices are increasing day by day along with reduction in availability. This emphasis on the use of renewable resources of energy. This problem can be solved by using solar assisted dryers because of various advantages. The overall objective of this study is to investigate the drying behavior and performance evaluation of locally fabricated hybrid solar dryer. Various parameters such as relative humidity, temperature, velocity of air, moisture content, solar intensity and air flow rate were recorded. The maximum value of solar irradiance was to be 963 Wm-2 at 12:30 hours. The solar irradiance was found above 800 Wm-2 in the time from 11:00 to 13:30 hours. The ambient temperature, inside air temperature, air velocity, air mass flow rate, temperature gradient and efficiency of dryer varied between 32-41 degree C, 41-82 degree C, 0.021-0.101 kg s-1, 1-24 degree C, 8-77% respectively. The proximate study of dried pear and peach was carried out to test it stability. The crude protein, crude fat, crude fiber and crude ash contents in untreated, ascorbic acid and NaCl treated pear and peach were determined.