Design and Development of Domestic Solar Dryer with Comparative Analysis of Nutritional Aspect of Dried Raisins

Abstract

Solar dryer technology is simple and can be implemented by households and small communities due to its simplicity. The suitable design of the absorber/collector is very vital for any solar drying system as the collector efficiency plays a key role in determining the overall system drying efficiency. To study the practical applicability of a developed solar dryer, grapes were dried in the drying chamber of a designed and developed solar dryer and for comparison, in open sunlight. Faster drying was noted for the grapes dried in the unit. The study on nutritional aspects indicated that solar drying process retained the major nutritional components like total sugars, total proteins and total lipids in raisins. The comparison between the solar dried raisins and open sun dried ones showed a higher ash content of 2.71% with solar dried ones and 1.95% in case of open sun dried raisins. The quantity of MUFA content was also affected by the varying drying practices implemented with 10.95% and 7.12% MUFA in solar dried and open sun dried raisins respectively. The drying technique also affects the bacterial load on raisins as observed in our current study with negligible bacterial growth on on solar dried raisins compared to open dried ones.