Transport Processes and Separation Process Principles (Includes Unit Operations) Fourth Edition

6.4. MOLECULAR DIFFUSION IN BIOLOGICAL SOLUTIONS AND GELS

6.4A. Diffusion of Biological Solutes in Liquids

1. Introduction

The diffusion of small solute molecules and especially macromolecules (e.g., proteins) in aqueous solutions are important in the processing and storing of biological systems and in the life processes of microorganisms, animals, and plants. Food processing is an important area where diffusion plays an important role. In the drying of liquid solutions of fruit juice, coffee, and tea, water and frequently volatile flavor or aroma constituents are removed. These constituents diffuse through the liquid during evaporation.

In fermentation processes, nutrients, sugars, oxygen, and so on diffuse to the microorganisms, and waste products ...