Mathematical model for prediction of intermittent drying and pressing process of mullet roe

A mechanical mullet roe drying process was designed to simulate the traditional intermittent sun drying-pressing process. A transient 3-dimensional diffusion equation was used to predict moisture content and moisture distribution using finite-difference techniques. Drying curves decreased in a logarithmic manner without a constant drying period from 25 degreesC to 40 degreesC. At the pressing stage, the moisture distribution became even and the drying rate increased during the subsequent drying stage as compared to the continuous drying curve at comparable drying time. Total drying time was effectively saved by 30% for 3 cycles of 12 h-12 h intermittent drying-pressing followed by continuous drying until the mullet roe reached a water activity (Aw) of 0.85.