1. Principles

1.1 Why dehydrate agricultural and food products?

Drying is an ancient process for preserving agricultural and food products. It converts perishable foodstuffs into stabilized products, by lowering the water activity (a _w ) to a value below 0.5. Most of the time, these products are stored at ordinary temperature, before being rehydrated for use in an industrial process or culinary preparation.

Drying is used in the food industry for a number of purposes:

• extend the shelf life of products (meat, fish, fruit, seeds, pasta, spices, tea, mushrooms, etc.);

• stabilize agricultural products (corn, alfalfa, rice, milk, etc.) and cushion the seasonal...