Buttercup Bakeries is part of the Goodman Fielder Group of Companies, a major Australian conglomerate. Buttercup employs 5,000 people, operates 30 bakeries around Australia and produces 30 percent of the country's bread.
Commercial bread baking generally involves a process called ëproofingí. In this process, loaf sized steel moulds containing the bread dough, pass through a low temperature proofing oven, triggering the yeast and other ingredients and making the dough soft and fluffy. The dough then passes through another very much hotter baking oven.
The temperature of the proofer oven is generally about 40 degrees Celsius with a relative humidity of 70-80 percent. Heat required for this part of bread baking is typically produced using steam from gas fired boilers. This is a high energy consuming and expensive way of heating the proofing oven. The energy consumption of a small size proofer at Buttercup Bakeries is about 5GJ per day (for one shift only) or almost 2000GJ per year. The cost of producing this heat using natural gas is about $10,000 per year. If oil or LPG were used the cost would be about $30,000 a year.
Loaves of bread are baked in the main oven at temperatures of 300 to 400 degrees Celsius. Excess oven exhaust gases are released into the atmosphere as wasted heat.