STEAMING FERMENTORS

The use of hot and pressurized steam to clean and sterilize fermentors is one of the most crucial steps in the fermentation process. Yet how much do we really know about the hot steam and its effects and limitations on the fermentation process?

Steam is the gas phase of water. Steam is produced when water passes its boiling point. Thus the temperature of steam is always very hot. It is possible to increase the temperature of the steam by generating steam under pressure such as those produced during autoclaving. By manipulating the pressure and controlling the temperature of the steam produced it enhances the value of steam as a sterilizing agent. This makes steam as a very useful method or technology in cleaning and sterilizing fermentors.

As a very hot gas phase, steam is most suitable in cleansing and sterilizing various components of the fermentors as well as in CIP and COP operations. Its power to sterilize and clean can even go beyond the fermentors but the plant environment such as other utensils and even floorings and processing machineries

The advantage of using steam is that it has the ability to penetrate the most hidden and inaccessible places

USING STEAM TO STERILIZE

Using steam to sterilize the fermentor depends more on the size of the fermentors

For small size fermentors the normal autoclave and the standard operating sterilization parameters apply. But for larger fermentors at the level of pilot or industrial fermentors there need to be adjustments in the sterilizing parameters

Steam sterilization of pilot and industrial fermentors is a bit more complicated as CIP needs to be applied. The fermentor and feed-system piping must be steam sterilized.

The accepted procedure involves heating the entire system with steam to a minimum of 121°C for 60 minutes or more. In case of very large fermentor installations large industrial fermentation systems often prove more difficult to sterilize. Steam heating to temperatures approaching 150°C for sterilization periods approaching 4 hours are often needed to insure that all hard-to-reach internal areas have been brought to minimum sterilization temperatures.

The efficacy of the operating regimes for steam sterilization has to be individually determined and validated for each type of fermentation

In fermentation technology we are often faced with the choice of two kinds of steam; the saturated or wet steam and the dry steam. The "dry steam" describes a system that produces a high temperature with "low moisture vapor". This vapor contains only 5-6% water and is much less dense than the air we breathe.

The trick to get a dry can of steam is to know the volume of your can and the amount of H20 in the can. Assuming the can to be a constant volume and that the H2O cannot escape, you pick the temperature and pressure needed to get "dry" steam

Not many using the autoclaves know the difference between the terms psi and psig. Find out….!

We can use pressurized hot steam to sterilize the vessels without using autoclaves. However the temperature of the steam would not be as high as in the autoclaving process. There are a number of mobile steamers in the market that can provide in situ hot steam. This method of sterilizing would be ideal in cottage fermentation industries