Extrusion Processing: An Advanced and Novel Technology for Development of Ready-To-Eat (RTE) Products

Ready-to-eat snacks and breakfast products are demanded rapidly day by day in the world market. To fulfill the RTE demand of consumer the novel, fast producing, versatile, uniformity, environmentally friendly and labour saving technology required by food scientists, manufacturers and industrialist. The extrusion processing technology is the latest novel technology which fulfils all these requirements. Extrusion cooking of foods is an operation in which raw food ingredients are forced to pass, in one or multiple varieties of situation of mixing, heating and shearing, through a die of specially designed to shape and puff dry the ingredients. Two or more raw food ingredients are combined to develop nutritious end products by the application of extrusion technique. Thermo-mechanical and shearing action during extrusion cooks raw mixture so that physico-chemical changes of the materials occur to carry out starch gelatinization, protein denaturation and enzyme inactivation, microorganisms and many other factors against to nutrition; all these occur in a shear situation, producing a plasticized continuous mass. In the present paper reviews the current development of RTE snacks in combination of different ingredients as well as the effect of extrusion process variables on physical, functional and textural properties such as expansion ratio, bulk density, hardness, crispness, water absorption index, etc. of extruded products. The control of process variables to produce nutritional balanced product is also important.