Optimization of time-temperature combination in intermittent drying of sweetened jackfruit (Artocarpus heterophyllus)

Abstract

Dehydrated jackfruit pulp processing is an emerging industry in Leyte, Philippines, but still relies on traditional drying method, resulting in slow production and inefficient energy use. This study investigated the impact of intermittent drying strategies on the drying kinetics and cost efficiency of jackfruit pulp dehydration to improve the processing method of drying jackfruit pulp. A 3×3 factorial experimental design was employed, incorporating three drying temperatures (60°C, 70°C, and 80°C) and three drying-to-tempering period combinations (30:480 min, 60:480 min, and 90:480 min). A control treatment employing a continuous drying treatment at 60°C was also conducted. Experimental results indicated that the Page model is sufficient to describe the drying kinetics of intermittently dried jackfruit pulp.  Continuous drying at 60°C achieved only 27% moisture content (wet basis) after 480 minutes (8 hours)—substantially higher than the recommended final moisture content of 3%–20% for dehydrated fruits. In contrast, samples subjected to intermittent drying with tempering phases required only 60 to 171 minutes to reach comparable moisture levels, corresponding to a 64.4% to 87.5% reduction in the overall drying time.  Achieving the target moisture content for gummy-type dehydrated fruits (12%–20%) needed an additional 12 to 40 minutes of intermittent drying, with shorter intermittent drying cycles and high temperature drying conditions yields optimal results.  The findings demonstrated that a drying schedule consisting of a 30-minute drying period at 80°C, repeated for two cycles, was most effective for producing sweetened dehydrated jackfruit pulp suitable for storage. This protocol produced a final product with a safe moisture level of 14.3% (wet basis). Each drying run consumed 0.41 kg of LPG and 2.01 kWh of electricity, resulting in a production cost of PhP 171 (2.89 USD) per kilogram of dried fruit.