During sterilization of a fermentation medium in a given bioreactor$\nabla_{heating}$= 12.56, $\nabla_{cooling}$ = 7.48 and the total value of V required for whole sterilization process is 52, where $\nabla$ is the design criteria.
Problem Analysis: Sterilization Design Criteria
The question provides key parameters for a bioreactor sterilization process: the design criteria values for heating ($\nabla_{heating}$) and cooling ($\nabla_{cooling}$), and the total value ($\nabla_{total}$) for the entire process. The objective is to find the design criterion value for the holding phase ($\nabla_{holding}$).
Given Values:
- Heating phase design criterion: $\nabla_{heating} = 12.56$
- Cooling phase design criterion: $\nabla_{cooling} = 7.48$
- Total process design criterion: $\nabla_{total} = 52$
Calculating Holding Phase Design Criteria
The total design criterion for the sterilization process is the sum of the design criteria for each distinct phase: heating, holding, and cooling.
This relationship is represented by the equation:
$ \nabla_{total} = \nabla_{heating} + \nabla_{holding} + \nabla_{cooling} $To determine the value of $\nabla_{holding}$, we rearrange the equation:
$ \nabla_{holding} = \nabla_{total} - \nabla_{heating} - \nabla_{cooling} $Step-by-Step Calculation:
- Substitute the given values into the formula: $ \nabla_{holding} = 52 - 12.56 - 7.48 $
- First, subtract the heating value from the total value: $ 52 - 12.56 = 39.44 $
- Next, subtract the cooling value from the intermediate result: $ 39.44 - 7.48 = 31.96 $
Result
The calculated value for the holding phase design criterion ($\nabla_{holding}$) is 31.96.
Important Questions from Sterilization of Air and Media
The decimal reduction time of a microbe during sterilization at $120 \text{ °C}$ with a first order thermal death rate constant of $1 \text{ min}^{-1}$ will be _______________ min (rounded off to 1 decimal place).
- A pilot sterilization was carried out in a vessel containing $100 \text{ m}^3$ medium with an initial spore concentration of $10^8 \text{ spores/ml}$. The accepted level of contamination after sterilization is 1 spore in the entire vessel. The specific death rate constant for the spore is $2 \text{ min}^{-1}$ at $121 \text{ }^\circ C$. Assuming no death takes place during the heating and cooling cycles, the holding time at $121 \text{ }^\circ C$ (rounded off to nearest integer) is ________________ min.
Decimal reduction time of a bacterial strain is $20$ min. Specific death rate constant in $min^{-1}$ (rounded off to two decimal places) is____.
Moist heat sterilization of spores at $121 \text{ } ^\circ C$ follows first order kinetics as per the expression:
$ \frac{dN}{dt} = -k_d N $
where, N is the number of viable spores, t is the time, $k_d$ is the rate constant and $ \frac{dN}{dt} $ is the rate of change of viable spores.
If $k_d$ value is $1.0 \text{ min}^{-1}$, the time (in minutes) required to reduce the number of viable spores from an initial value of $10^{10}$ to a final value of 1 is (up to two decimal places)______.
- Decimal reduction time of bacterial spores is 23 min at $121 \ °C$ and the death kinetics follow first order. One liter medium containing $10^9$ spores per mL was sterilized for 10 min at $121 \ °C$ in a batch sterilizer. The number of spores in the medium after sterilization (assuming destruction of spores in heating and cooling period is negligible) will be ____________________ $ \times 10^7$.
