Question

Why do dried fruits and beans swell when cooked?

Answer 1

Dehydrated foods are at a compressed size, so adding water will cause them to inflate as they soak it in.

Answer 2

Dried fruits and seeds have little water content When cooked the steam in the cooking permeates into the seeds increasing water content. This causes them to swell as their mass increases. On the occasion, they burst to because the testa or skin cannot support the increasing size of the seeds.