Hybrid solar dryer for sugar‐palm vermicelli drying

Abstract Sugar palm is an abundant palm in Indonesia and widely used for various foods, one of which is vermicelli. During vermicelli production, local farmers still implement open‐sun drying, which reduces the quality of vermicelli, requires long periods of time, and cannot be performed during poor weather. Therefore, in this study, a new method of vermicelli drying is introduced using a hybrid solar dryer, which consists of a solar dryer and an additional heater powered by liquefied natural gas. Hybrid solar drying is conducted at 40, 60, 80, and 100°C. With 2 hr of drying time, the final moisture contents of vermicelli dried using hybrid solar dryer have satisfy the standard limit, while the open‐sun drying and natural solar drying do not, indicating that hybrid solar drying is faster and more effective. Vermicelli drying occurs at the falling‐rate period and increasing drying temperature from 40 to 100°C increases dryer efficiency, energy utilization ratio, and exergy efficiency, from 13.02 to 17.02%, from 0.18 to 0.32, and from 67.4 to 83.6%, respectively. Although the overall quality of dried vermicelli is acceptable, increasing drying temperature from 40 to 100°C result in the damaged vermicelli surface as evident from SEM analysis and degradation of vermicelli whiteness value from 87.2 to 82.5. Practical applications The drying process is playing an important role in heat sensitive products dehydration. The present study provides an investigation of potential use of solar energy for drying of vermicelli which combine with the natural gas heating process. The results show that hybrid drying system could enhance the product quality of vermicelli and also reduce the drying process. During drying, proximate components of vermicelli essentially do not change but it alters the color of product.