Study of activation energy and moisture diffusivity of various dipping solutions of ivy gourd using solar dryer

The study is aimed to enhance the shelf life of ivy gourd through the solar drying method in open, forced, and natural convection mode. Ivy gourd is treated as the primary agent to prepare medicines and the stems, leaves and flowers are used to cure diseases related to diabetics, ulcer and skin. The normal shelf life is 2-3 days and it can be increased up to 6 months with an effective drying process. The experiment is intended to find the best drying process among the open, natural, and forced convection mode with an initial dipping method with ascorbic acid, lemon juice, sugar solution, honey solutions individually, and a control sample (without dipping). A 3 kg sample of ivy gourd is dipped in 10 g/L of each of the solutions and it is used for the three drying processes individually. The obtained results are indicating that the forced convection method for ascorbic acid is best among the other drying method, with the highest moisture diffusivity is 7.88 × 10^-8 m²/s and the lowest activation energy of 21.12 kJ/mol. The lemon juice sample is found to have better sensory appeal in terms of colour (darkness) and shrinkage followed by honey, ascorbic acid, and control sample, whereas the honey-dipped sample offers a better taste followed by lemon juice-dipped samples, control, and ascorbic acid-dipped samples, respectively. The influence of dipping solution and drying mechanisms on the functionalities of drying are discussed with suitable illustrations.