Elements of the Baking Process and Their Control

Abstract

Since the baking process constitutes the most energy-intensive operation of bread production, and 30-40% of all bread faults are due to deficiencies during baking, the optimization of the controllable variables merits some consideration. The central object for such considerations is the shaped and proofed dough-piece, and in order to understand what changes the dough-piece undergoes, and how they can be influenced by the baker, the baking process must be analysed into the various aspects involved in its technical management. These can be broadly analysed as: heat-energy input and temperature; heat-transfer; humidity; and baking-time. Heat-energy Input and Temperature The internal energy of a system is the sum of the kinetic energy of chaotic motion of the molecules, the potential energy of their interaction, and the intramolecular energy. This energy can be transferred from one body to another in two ways. One is by mechanical interaction, when work is done by mechanical or electromagnetic forces; and the other is by thermal interaction, whereby energy is transferred by the chaotic motion of the molecules to produce heat-conductivity or thermal radiation. The quantity of heat-energy produced by the thermal interaction of bodies is referred to as the 'quantity of heat' or simply as 'heat'. The unit of heat in the SI system is the joule, expressed in the CGS system as calories. 1 calorie = 4·1868 joules (1). The quantity of heat required to increase the temperature ofa body of unit mass from to to t = to + dt, and is referred to as dQ. The mean specific-heat within the temperature interval (t-tol is the ratio dQ/dt, the limiting value of this ratio is defined as the true specific heat at the temperature to, the true specific heat depending on temperature. However, this dependence on temperature is normally disregarded, and specific heat is defined as the quantity of heat required to raise the temperature of a body of unit mass from tOC to (t + 1 tC at any temperature t. The quantity ofheat-energy dQ absorbed by a body of mass m, when its temperature is increased by dt is given by: dQ =smdt where s is the specific heat. The specific heat also depends on the conditions under which the heating takes place, when under constant pressure, it is referred to as 'specific heat at constant pressure', if there is no volume change, then it is termed 'specific heat at constant volume'. The former always being greater than the latter. This concept is applicable to substances in the gaseous state, for solid state substances, the difference is 553 C. A. Stear, Handbook of Breadmaking Technology