Prepared by: BHUMI R. PATEL

Second semester m.sc. Biotech

M.U.I.B.

Batch sterilization process

Sterilization : it is a term referring to any process that remove or kills all forms of microbial life including transmissible agents present on a surface, contained in a fluid, in medication or in a compound such as biological culture media.

introduction

The highest temperature for batch sterilization is 121°c

The following information must be available for the design of batch sterilization process:

I. A profile of the increase and decrease in the temperature of the fermentation medium during the heating and cooling periods of the sterilization cycle.

II. The number of microorganism originally present in medium.

III. The thermal death characteristics of the design organism.

When running a thermal batch sterilization, a system goes through 3 steps: heating, holding, and cooling.

Heating requires the addition of energy through a jacket on the vessel.

The temperature is increased until it reaches the sterilization temperature where it is held for a set period of time.

Finally, the system is cooled to bring the sterile media back to the desired temperature.

Calculation of del factor during heating and cooling

The Del factor to be achived during the holding time may be calculated by difference:

Calculation of the holding time at constant temperature

The relationship between Del factor, the temperature and time is given by this equation:

∆= A.t.e ⁻⁽ Deindoerfer and humphrey produced integrated forms

of the equation for a variety of temperature-time profiles, including linear, exponential and hyperbolic.

Calculation of the Del factor during heating and cooling

Temperature is increase over a time period

Most widely used techniqueIt is versatile : it can be use for different reaction

everyday. Complete conversion is possible. It can be properly sterilized. Little risk of infection and strin mutation.

Advantages of batch sterilization

If a cooker serves a large number of fermenters complex pipework would be necessary to transport the sterile medium, with the inherent dangers of contamination.

High labour cost. Much idle time: sterilization, growth of inoculum,

cleaning after a fermentation. Safety problems: when filling,emptying ,cleaning.

Disadvantages of batch sterilization

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