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Learn the toughest concepts covered in Microbiology with step-by-step video tutorials and practice problems by world-class tutors.

11. Controlling Microbial Growth

Review of Physical Methods to Control Microbial Growth



Review of Physical Methods to Control Microbial Growth

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in this video, we're going to review some of the information that we've already covered in our previous lesson videos on the physical methods to controlling microbial growth. And we're going to do that by completing the interactive blanks that we have down below in this table. And so notice that this table is all on the physical methods to controlling microbial growth. And we have the specific control method on the left hand column and we have a description of the control method in the right hand column. And so the very first method that we have here is dry heat, which recall is going to be using heat that has absolutely no moisture or no liquid content. And so this is going to include uh techniques such as incineration, burning with a direct flame or using a hot air oven. Next, what we have is moist heat and moist heat as its name implies, is going to be heat that actually has moisture or liquid content. And so this is going to include techniques such as boiling, as well as using um pasteurization and pressurized steam using an autoclave. Next we have our low temperatures rather than applying heat using low temperatures and low temperatures will actually inhibit the growth of microbes and that will help to preserve foods. And so we can use either refrigeration or freezing as a way to implement low temperatures. Next, what we have is desiccation and desiccation is really the process of drying out. And so you can think of a cactus which is found in deserts and really dry areas to help remind you of desiccation and the fact that this is the process of drying out or simply removing moisture from cells in order to kill microbes. Next what we have is liable. Ization and liberalization is the process of freeze drying and so it's almost like combining the low temperatures and the desiccation into a single method. And so the Lion realization. This process of freeze drying is widely used to preserve many different types of foods, including some of your favorites like ice cream. Perhaps next, what we have is filtration and filtration is the process of using filters with really, really small pores, pores that are so small that it makes microbes appear large and the microbes are too large to fit through the pores. And so it filters out the microbes and allows the liquid or the air to pass through and become basically sterilized. And so um recall that the HEPA filter. The high efficiency particulate air filter is a specific type of filter for filtering air. Next, what we have is irradiation and irradiation is the process of exposing an object to radiation uh in order to kill microbes. And recall that we talked about two different types of radiation ionizing radiation, which has high penetrative power and has sufficient energy to ionized molecules creating reactive oxygen species. And then there's also non ionizing radiation, which has less penetrative power and less energy. And it does not, it must be used directly on the microbes in order to be effective and then last but not least. What we have is high pressure processing, which, as its name implies, is going to be a process that uses extremely high pressures in order to destroy and damage microbes, damage and kill microbes. And so this year concludes our brief review of the physical methods to controlling microbial growth. And we'll be able to get a little bit more practice moving forward. And then we'll talk about the chemical methods to controlling microbial growth. So I'll see you all in our next video.

Which of the following microbial control methods does not actually kill microbes or inhibit their growth but instead removes them physically from samples?


Which method of physical microbial growth control requires extremely high temperatures and long periods of time to kill microbes?