 Again, in this module, we will talk about the effect of sterilization time and temperature to the medium content. So, as concerned, the sterilization process while dealing with the effect on fermentation medium, we can say that the thermal destruction of essential medium component. So, approximately, this also fit to the first order reaction of kinetics. So, the destruction of the essential medium can be expressed by this equation that xt over x naught is equal to e powered by minus kT. Here, the xt is the concentration of the nutrient after heat treatment at any time period. So, x naught is the original concentration of the nutrient at any onset of the sterilization and k is the reaction rate constant. So, the effect of temperature on the reaction rate constant may be expressed by this Arrhenius equation. ln k is equal to ln a minus e over rT, here you can say that a is the Arrhenius constant and e is the activation energy and r is the gas constant and t is the absolute temperature and k is the reaction rate constant. So, this equation actually show the effect of temperature to the rate of reaction which called as thermal destruction rate. So, if we draw the graph or a plot between the natural logarithm of the reaction rate against the reciprocal of the temperature that give a straight line and the slope of that straight line is equal to minus e over r as the value r is the gas constant that is the fixed the slope of the graph that are determined by the value of the energy of activation. So, the activation energy for the thermal destruction of basillist stereothermophilus spores has been cited in a literature 67.7 kilo calorie per mole whereas, the thermal destruction of the nutrients is 10 to 30 kilo calorie per mole. So, here you can say that the activation energy of the thermal destruction of basillist stereothermophilus here you can you should know that the basillist stereothermophilus is known as indicator organism for sterilization process. So, when we have to check the sterilization either media as properly sterilized or not we applied basillist stereothermophilus. So, the basillist stereothermophilus has the thermal deactivation or destruction that is 67 as well as the thermal destruction of the nutrient is 10 to 30 depending upon the different components. So, as concerned the Arrhenius plot of these two reaction we can see in this slide that how they what is the relationship. So, here you can see that the solid line show the high activity energy spore destruction and the dotted line show the low activation energy nutrient destruction. You just observe here the graph between the log of nature of rate constant over the reciprocal of the temperature. So, when we increase the temperature the sterilization is more as compared to the loss of the nutrients. So, if we have a by this relationship which show the effect of activation on spore and nutrient destruction we can easily see that the high temperature have more effect on the contaminator rather to be that we can say that that is the effect, but the severity of the effect is more as compared to the nutrient. So, this relationship can lead us to the further practical aspects of the sterilization process. So, thus by considering the difference of the activation energies of spore destruction and nutrient degradation with the increase in the temperature as I have already told you that at high temperature the destruction of the spore is maximum as compared to the nutrient degradation or a denaturation. So, by this relationship it would be a pure advantage to imply a high temperature for a short time rather to have a low temperature for a prolonged time. So, if we have a low temperature and a prolonged time treatment then there will be a more loss in the nutrients. So, that is why it is ideal technique would be to have the heat of fermentation medium to high temperature at which we have a very short holding time. So, we can discuss in a later module about the holding time and then, but it is obviously impossible to heat a batch of many thousands of liters in a tank to a high temperature for a short time. And same on then if we have to cool down that just to avoid the heat effect we have to be quickly cool down that, but on a larger volumes on a deep fermentation it is not possible. So, that considerably prolong the sterilization time. So, the only practical method for materializing the object of a short time high temperature treatment is to sterilize the medium in continuous stream rather to have a batch stream. Because in a batch there will be a more depth and there will be a more volume. So, we can apply the high temperature for a short time in a continuous stream rather to have a single stored volume.