A typical batch fermentation process starts with sterilization so that all micro-organisms found in the mash and reactor are completely destroyed. The mash is heated in the fermenter or a special cooking vessel by injecting live steam or by means of steam coils set in the vessel. Holding the temperature at 121°C (250°F) for 30 minutes is usually adequate to destroy all living organisms in the mash. However some processes require higher temperatures. As shown in Figure 1, a heating/cooling jacket maintains the temperature of the fermentor.