Chapter 22, Problem 1Q

Summary Introduction

To write:

The effectiveness of autoclaving, boiling, microwaving and dry heating.

Introduction:

Sterilization is the killing or removal of all the living microorganisms, including the bacterial spores that are highly resistant. It is usually carried out by autoclaving or moist heating, boiling, microwaving and dry heating as the effective methods and consists of maximum exposure to steam as well.

Explanation of Solution

Autoclaving is a moist heat sterilization method that uses high-pressure steam. This process works by the concept that the boiling point of water or steam increases when it is under pressure. The steam inside the autoclave attacks the microorganisms and kills them. Boiling is a simple method of heating water to a high temperature of 100°C, kills most of the pathogenic microorganisms.

Microwaving is a thermal process and most of the processed foods are heat treated to kill the microorganisms. It does not kill the microorganisms completely. Dry heating kills or removes all the microorganisms, including bacterial spores. It requires a longer time for exposure as well as higher temperatures as well. Its higher temperature kills the microorganisms using a destructive oxidation method. Moist heating or autoclaving is the most effective way of killing all the microorganisms, because of its ability to penetrate microbial cells. It is followed by dry heating and then, boiling is effective as it produces heat more thoroughly and flashover can be avoided as compared to microwaving.

Conclusion

Thus, the effectiveness of moist heating or autoclaving is the highest, followed by dry heating that requires longer time and the temperature, then boiling with temperature of 100°C and lastly, microwaving which is a thermal process.