Effect of drying temperature on bioactive compound content of sliced shallots using photovoltaic ventilation solar dryers

In this study, shallots slices were dried using a photovoltaic ventilated solar dryer, and temperature analyzes and bioactive compounds were carried out to assess the system’s performance in terms of energy efficiency compared to open sun drying. Photovoltaic ventilation solar drying consists of five main components: a solar panel to capture solar energy, a battery to supply electrical power to other features, temperature control to regulate the temperature during drying, ventilation fans, and drying chambers. Drying lasts for 8 hours. The results obtained that the higher the intensity value, namely the temperature profile of the dryer, it is known that the drying chamber absorbs sunlight, the higher the temperature required for the drying process. The fastest drying rate occurs in photovoltaic ventilation solar drying at a temperature variable of 50°C, which is 12.15 g/hour. The average efficiency of drying sliced shallots traditionally for 8 hours is 18.73%. The mathematical model of thin-layer drying that is suitable is the Page model because it has the highest R2 value of 0.9871 and the lowest RMSE and x2 values are 0.03247 and 0.00141. In addition, due to excessive heat, the decrease in bioactive compounds on drying at higher temperatures was caused by damage to bioactive components such as polyphenol compounds.