1 Mixing in the food industry : trends and challenges

Mixing is a fundamental unit operation in the chemical, pharmaceutical and food process industries. Mixing increases the homogeneity of a system by reducing non-uniformity or gradients in composition, properties or temperature. Besides the primary objective of homogeneity, secondary objectives of mixing include control of heat and mass transfer rates, reactions and structural changes (Harnby et al. 2001). In food processing applications, additional mixing challenges include sanitary design, complex rheology, desire for continuous processing and the effects of mixing on final product texture and sensory profiles. The mixing of liquids, solids and gases is one of the most common unit operations in the food industry. Mixing is frequently employed to develop the desired product characteristics such as texture rather than simply ensure product homogeneity. If mixing fails to achieve the required product yield, quality, and organoleptic or functional attributes, production costs may increase significantly.