Matter starts to be deformed or to flow only when it is acted on by forces which may be applied deliberately (such kneading of a dough) or accidently (dropping eggs), and there is also the all-pervading force of gravity with cause ‘soft’ bodies to flow and lose their shape.
Many objective methods for measurement of food quality involve measurement of some aspect of texture, such as hardness crispness or consistency. Texture is related to the rheological properties of food, which determine how is responds when subject to forces such as cutting, shearing or pulling.
Rheological properties can be divided into three main categories. A food may exhibit elastic properties, viscous properties or plastic properties or a combination.
The science of rheology has many applications in the field of food acceptability, food processing, and handling.
A number of food processing operations depend heavily upon rheological properties of the product at an intermediate stage of manufacture because this has a profound effect upon the quality of the finished product.
From a rheological standpoint, solutions of small molecules or monomers represent the simplest food materials, which can be characterized by a single value of viscosity that is function of temperature type of molecule and concentration.
Rheology is important to the food technologist because it has many applications in the three major categories of food acceptability:
*Appearance
*Flavor
*Touch
The principle of food rheology
