Performance evaluation of indirect solar drying system for potato slices: Comparative analysis with open-sun drying method

In this study, a partially portable indirect solar dryer (ISD) was constructed and potato slice drying characteristics were analyzed compared to the open-sun drying (OSD) method. Potato slice samples were prepared and the experiment was carried out for two days. Weight reduction environment temperature, collector plate temperature, drying chamber temperature, and drying chamber inlet temperature were recorded from 10 AM to 6 PM. every 30 min to analyze various drying characteristics. Initially moisture content (MC) of the potato slices was 83 +/- 2 % (wb); after drying the final MC was 11.7 +/- 2 % (wb) for OSD and 7.7 +/- 2.0 % (wb) for ISD system, both in 16 h. The highest drying rate (DR) of potato slices was 18.8 (g water/g solid h) after 8 h of open sun drying, and 16.97 (g water/g solid h after) 8 h. Rehydration ratios for OSD and ISD were found 4.32 and 4.20, respectively. Shrinkage factor for OSD was 61 %, whereas ISD had a shrinkage ratio of 70 %. The highest color change values were 6.32 and 8.13 in the ISD and OSD, respectively. Water activity was reduced from 0.95 to 0.42 in ISD and from 0.95 to 0.59 in OSD.