Fish Products and Byproducts Technology

Unit 3- Salting and Drying

3.2.2. Falling rate period
What is falling rate period in Drying?
It is second phase of drying. As the water evaporates from the surface of the fish, the water present in the interior of the muscles is transferred to the surface. This is mainly by diffusion of the water. This process is generally slower than the surface evaporation, and hence diffusion limits the drying rate. This period is generally characterized by a slowly decreasing rate of drying, partially due to the fact that the drier the product is, the slower will be the diffusion of water to the surface. Thus this second phase is called the falling rate period.