KEYWORDS: Solar-dryer, Post-harvest, losses, India, vegetables.

It has been reported that, globally, almost one-third of the food produced from primary production through to consumption level is lost or wasted, which amounts to 1.3 billion tons and is valued at US$ 1 trillion annually. This implies that the resources used and greenhouse gas emitted in producing wasted and lost food are inefficient and have contributed to food shortages and malnutrition. Official figures set the economic values of post-harvest losses of agricultural produce at INR 926.51 billion (US$ 15.19 billion) in 2014.
Drying has been an ancient method and is unavoidable when extending the shelf life of food items. However, inappropriate drying of food items can result in undesirable quality of dried food items. With the anticipated increase in agricultural productivity due to the expected increase in population, the study of new technologies and solutions to problems related to post-harvesting has become necessary, particularly concerning value addition and storage options. While the performance analysis of solar dryers has been extensively studied, there needs to be more focus on the drying kinetics of different vegetables using MMFC-SD. The few available ones either focus on one or two vegetables.
This study investigates the performance analysis by comparing the designed Mixed-Mode Forced Convection Solar Dryer with a Natural Convection Solar Dryer against Open Sun Drying by studying the drying kinetics of onions, tomatoes, bitter gourds, and potatoes. Different experiments were conducted to estimate the moisture content expressed as percentage moisture content, drying rate, and moisture ratio of each vegetable. More so, the study showed the Analysis of variance on the means of the drying rates and also conducted an economic analysis of the designed MMFC-SD.
The study revealed that the MMFC-SD dried fresh-cut tomatoes to 10% final moisture content within 13.5 hours compared to NC-SD and OSD of 18% and 20% final moisture content within 12.5 hours and 14.5 hours, respectively. More so, within 11 hours, the MMFC-SD dried fresh-cut onions to a final moisture content of 8.9% -17.8%. In addition, the designed MMFC-SD removed 85%-85.3% of the moisture content of the cut potatoes, while OSD removed 80%. Furthermore, the MMFC-SD dried cut bitter gourd to 6.67% final moisture content within 4 hours.
Lastly, the MMFC-SD trays loaded do not significantly affect the drying rates of the vegetables (potato and onion), as evident in the ANOVA analysis results of >.05 p-value. However, the analysis shows significant differences in the drying rates of the three methods used to dry tomatoes, potatoes, and onions. The ROI of MMFC-SD is estimated to be 8.5 months.