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B atch sterilization process. Prepared by: BHUMI R. PATEL Second semester m.sc. Biotech M.U.I.B. introduction.
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Batch sterilization process Prepared by: BHUMI R. PATEL Second semester m.sc. Biotech M.U.I.B.
introduction • 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.
The highest temperature for batch sterilization is 121°c • The following information must be available for the design of batch sterilization process: • A profile of the increase and decrease in the temperature of the fermentation medium during the heating and cooling periods of the sterilization cycle. • The number of microorganism originally present in medium. • The thermal death characteristics of the design organism.
Calculation of del factor during heating and cooling • 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 the holding time at constant temperature • The Del factor to be achived during the holding time may be calculated by difference:
Calculation of the Del factor during heating and cooling • 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.
Advantages of batch sterilization • Most widely used technique • It 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.
Disadvantages 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.