Drying characteristics of amla candy in solar tunnel greenhouse dryer

In this article, a forced convection solar tunnel greenhouse dryer is proposed for food processing, especially for amla candy. An investigation has been made to demonstrate the usefulness of thermal and mathematical modeling in forecasting the drying kinetics of agricultural commodity. A system of partial differential equations concerning the heat and mass transfer were presented and solved by Gauss Jordan elimination technique to determine the temperature of air during drying. The predicted air temperatures within the dryer agreed well with the experimental temperature data. Thin layer characteristics of the product were described by six different mathematical models. The statistical and graphical validation is executed to confirm the validity and accuracy of selected models. However, based on the drying curves, Modified Page model was designated as the best model. The dryer is better for mass production, superb transportability, effortless tracking, easy assembly of tunnels on the site makes it a Do It Yourself (DIY) kit. PRACTICAL APPLICATIONS: Basically the drying is known as an energy‐intensive process, and in industries, it consumes a huge quantity of energy; whereas in the present time, energy saving is needed to pay adequate attention. However, the traditional method for processing of amla candy (open sun drying) is thermally inefficient due to several problems like contamination of product from foreign materials, degradation by overheating, untimely rainfall, uncontrolled drying, and long drying time. In order to minimize the limitations of open sun/mechanized drying and to improve the quality of dried product, author developed a simple and easy to use solar tunnel greenhouse dryer. The quality of solar dried amla candy is far better and could fetch around 20% extra price than that of open sun/mechanized drying. To make amla a fruit of mass, products need to be developed which are attractive, tasty and therapeutic values. Among various amla food products, candy is very popular.