Famurewa, O.K.E. and Famurewa, J.A.V. (2014). Determination of energy involved in a stepwise size reduction of maize, using a numerical approach. IOSR Journal of Mathematics. 11(1): 61 - 65.
Introduction
Maize is an economic crop. Primary processing methods of this food in dry state requires size reduction, an energy driven unit operation.
Maize is an important agricultural crop that plays significant roles in the diet of the people all over the world particularly in the developing nations. FAO (2012) respectively ranked maize as third, important cereal in the world. According to Kent and Evers (1994), maize grain contains about 10.8% moist ure, 10.0% protein, 4.3% fat, 1.7% fiber, 1.5% ash, and 71.7% starch
Size reduction is the unit operation in which the average size of solid pieces of food is reduced by the application of grindin
g, compression or impact forces (Famurewa, 2007).
Size reduction into flour is an important food processing operation because a large proportion of food materials are reduced into flour before conversion into finished products.
One measure of the efficiency of the milling operation is based on energy required to create new surfaces. Size reduction is one of the least energy - efficient of all the unit operation and the cost of power is a major expense in crushing and grinding, so the factors that control this cost are important (McCabe et al ., 2005).
During milling, Kinetic Energy is dissipated on the material in excess of its internal strength which causes rupture along the line of cleavages resulting into smaller particles (Famurewa , 2007).
Some benefits of size reduction in food processing include; increase in the surface -area-to-volume ratio of the food which
increases the rate of drying, heating or cooling, improvement in the eating quality or suitability of foods forfurther processing and increase in the range of products available.
The relation ship between the comminution energy and the product size obtained for a given feed size has been researched extensively over the last century. Theoretical and empirical energy -size reduction equations were proposed by Rittinger (1867), Kick (1885) and Bond (1952), known as the three theories of comminution; and their general formulation by Walker
et al. (1937). Finally, Hukki (1962) proposed the revised form of the general form of comminution and suggested that the energy - size relation is a combined form of these three laws.
Walker et al. (1937) proposed the following equation, for a general form of comminution