In this video, we're going to briefly introduce irradiation as a method of controlling microbial growth. Irradiation is the process by which an object is exposed to radiation. It can be used to destroy microbes and control microbial growth. Radiation is defined as the emission or transmission of energy as either electromagnetic waves or as moving subatomic particles. In this video, we will briefly introduce two types of radiation:
- Ionizing radiation: This type of radiation has penetrative power and is capable of penetrating deeper into objects. It has sufficient energy to remove electrons and, therefore, can ionize atoms or molecules. Since electrons are being removed, there is an imbalance of protons and electrons. Ionizing radiation, with its penetrative power and high energy, can harm cells directly by destroying molecules within the cells such as DNA and membranes. It is also capable of creating reactive oxygen species (ROS), which are chemicals that are highly reactive and can lead to damage within the cells themselves. Thus, ionizing radiation can cause direct cellular damage or create reactive oxygen species that cause internal cellular damage.
- Non-ionizing radiation: As the name implies, non-ionizing radiation lacks the energy to ionize atoms or molecules. It has less penetrative power and therefore must be used directly on the microbes. It cannot penetrate through packaging or other barriers. Examples of non-ionizing radiation include UV ultraviolet light, which can damage DNA and proteins within cells to help control microbial growth. Additionally, microwaves can generate lethal amounts of heat to kill microbes.
We can enhance our understanding of irradiation by referring to an image of the entire electromagnetic spectrum. The spectrum shows that waves start off really long and become progressively shorter. The shortest wavelengths, having the highest amount of energy and most penetrative power, represent ionizing radiation. Conversely, waves that are longer have less energy and less penetrative power, representing non-ionizing radiation. For instance, radio waves have very long wavelengths and are therefore considered non-ionizing radiation.
In the video, we also show an image of a laboratory using ultraviolet light to sterilize the environment and eliminate microbes within a culture hood. Moreover, we present an image contrasting two oranges: one non-irradiated orange showing microbial growth on its surface, and another that has been irradiated showing no microbial growth. This visual aid demonstrates how irradiation can control microbial growth and enhance safety in the use of products and consumption of specific types of food.
This concludes our brief lesson on irradiation as a method to control microbial growth, and we will have opportunities to apply these concepts as we progress in our course. I'll see you all in our next video.