Food rheology

this contain a brief information about food rheology and different method to measure . Its not detailed information detailed one I will upload soon

1. Food rheology By Pallavi B.S Food technologist Contact :[email protected]

2. INTRODUCTION The term comes from Greek word rheos meaning to flow. It is applicable to all materials. It was founded by two scientists professor Marcus Reiner and professor Eugene Bingham The Greek philosopher Heraclitus described rheology as “Panta rei” – everything flows.

3. Rheology is the branch of science that deals with the flow and deformation of materials. E.G.: Liquid food. Solid food. WHAT IS RHEOLOGY?

4. IMPORTANCE OF FOOD RHEOLOGY Physical characterization of fluid and semi-solid foods. Process engineering and process design. Development of new products. Quality control during production and of final products. Instrumental evaluation of sensory properties. Indirect understanding of food microstructure. Shelf life testing.

5. Rheological methods 1. EMPIRICAL METHOD: The food industry uses many empirical instruments to measure the flow behaviour of food products. It is applied in quality control, correlation to sensory data, or even serve as official standards of identity. Since they do not measure fundamental properties, they may appropriately be called indexers. Many empirical instruments have been developed to evaluate the flow behaviour of dough. It is one of the most widely used dough mixers is the Farinograph . Most empirical test measure poorly defined properties that have been shown by experience to be related to textural quality. TYPICAL EMPIRICAL TESTING INSTRUMENTS ARE; Haughmeter . Chatillon pressure tester. Warner bratzler shear. Penetrometer. Mixograph.

6. Imitative tests measure various properties under conditions similar to those to which the food is subjected in practice, that is, the properties of the materials during handling and the properties of the food during consumption. Instruments to measure the first group of properties include butter spreaders, which give a measure of the spreading properties. various mixing and load –extension meters , which measure dough –handling properties . In the second group are various tenderometers , which stimulate the chewing action of teeth. 2. IMITATIVE METHOD

7. APPLICATIONS OF FOOD RHEOLOGY Cereals Dairy products. Meat. Fruits. Vegetables. a. CEREALS Viscosity , elastic modulus and tensile strength are the out standing factors in determining the behavior of wheat flour dough. Compressibility, crispness and breaking strength of baked product play a role in acceptability by the consumer.

8. Kernel hardness : Methods to determine wheat hardness include determination of , Power to grind a sample. Time to grind under specified conditions on a burr-type mill. Resistance to grinding. Particle size of ground wheat. Recording dough miners : types of recording dough miners are, Barbender farinograph . Mixo graph. Barbender farinograph : Measures plasticity and mobility of dough subjected to a prolonged , relatively gentle mixing action at constant temperature.

9. 1. STARCH For the evaluation of starch products three aspects of starch rheology are important: The alterations of rheological properties during pasting. Hot paste viscosity and its variations with time. Change in rheological properties during and after coding of the paste. 2.DAIRY PRODUCTS BUTTER: The resistance to deformation under its own weight is an essential quality of butter. Investigation have been under way to measure instrumentally some of rheological properties of finished butter. The different methods of measurement include the penetrometer method, sectility method, extrusion method, single bean method, spread ability. 3.CHEESE The rheological behavior of cheese, milk, and curd have been evolved. Plastic bowl and new torsiometer for measuring the firmness of the coagulation before cutting. Curd pitching tester for assessing the condition of the curd on pitching

10. Ball compressor or hardness tester have been developed to the stage where they can be usefully employed in cheese making. Now a days the study of rheology on India milk products like khoa , channa , robri etc.. 4. MEAT Tenderness is the most important factor affecting consumer evaluation of meat quality and acceptability, Meat tenderness devices are divided into four types depending on upon their mode of action, Shear. Penetration. Biting. Mincing . Warner-bratzler shear press is most commonly used to evaluate acceptance of meat. Pork tenderness is measured by, Warner –bratzler shear press. Grinder tenderometer. Denature tenderometer. 5.FRUITS AND VEGETABLES The instruments used for evaluating texture of fruits and vegetables are , Compressimeter , Penetrometer, Shear –testing devices , consumption during grinding.Smaller extent instruments measuring energy.