Chemical Preservation of Perishable Products - Online Tutor, Practice Problems & Exam Prep

Chemical Preservation of Perishable Products

In this video, we're going to begin our lesson on chemical preservation of perishable products. Most of the chemicals that we've covered so far in our previous lesson videos can really only be used to clean, disinfect, or sterilize non-food items. But a lot of those chemicals are not safe to ingest or to eat, so they cannot be used to preserve food items. The chemicals that are used in food preservation must be nontoxic and safe for ingestion or safe to eat. Recall from our previous lesson videos that we defined preservation as the process of delaying spoilage of perishable products, and perishable products are simply items that are likely to go bad quickly such as vegetables and fruits. Chemicals such as organic acids, nitrates, and nitrites are all chemicals that are commonly used in food preservation. Moving forward in our course, we're going to focus on those chemicals. We'll first talk about the organic acids, and then later in a separate video, we'll talk about the nitrates and the nitrites. I'll see you all in our next video.

Organic Acids Used in Food Preservation

This video, we're going to begin our lesson on organic acids used in food preservation. And so organic acids, as their name implies, are going to be any organic compound that is going to have acidic properties. Examples of these organic acids that serve as antimicrobial agents to kill microbes include benzoic acid, sorbic acid, and propionic acids. Benzoic acid, sorbic acid, and propionic acids are all weak organic acids that can be added to food products such as bread and juices in order to prevent microbial growth. And what they do is they create an acidic environment. This acidic environment that these acids create is going to prevent the growth of most bacteria and molds by affecting their cell membranes.

If we take a look at our image down below, we can see we're showing you the structure of a specific organic acid, and this is benzoic acid, the structure of benzoic acid. Notice that it is an organic molecule that contains carbon and hydrogen, and it is containing a carboxylic acid group right here, so it has acidic properties. Notice here we're showing you some bread that has been treated with organic acids, and it looks pretty safe and healthy to eat. And notice over here on the right, what we're showing you is some bread that has no organic acids in it. Notice that lots of mold and microbes are able to grow on that bread, and this bread is not really safe to eat. This shows how organic acids can be used as chemicals for preserving foods.

This here concludes our brief lesson on organic acids used in food preservation, and we'll be able to talk about the nitrates and the nitrites in our next lesson video. So I'll see you all there.

Which chemical is added to bread to prevent to growth of mold?

• A. Acetic acid.
• B. Lactic acid.
• C. Sorbic acid.
• D. Quats.

Nitrate & Nitrite in Food Preservation

In this video, we're going to talk about the use of Nitrate and Nitrite in food preservation. Nitrite is actually the reduced form of Nitrate. Nitrate and Nitrite are very similar in their structures otherwise. Nitrate and Nitrite are primarily used for preserving processed meats in 2 specific ways. The first way is that they inhibit the germination of endospores formed by the bacteria Clostridium botulinum. By inhibiting the germination of these endospores, it prevents the growth of this bacteria, which could otherwise be very toxic.

The second way in which these nitrates and nitrites are primarily used for preserving processed meats is that at really high concentrations, they can actually be used to preserve the pinkish color that is associated with meats, for example, hot dogs. If you take a look at the image down below, you'll notice on the left-hand side we're showing you a nitrate, the chemical structure for the nitrate. And, on the left-hand side, we're showing you a fresh steak that has been treated with these nitrates. Notice that it has the pinkish color and that there are no Clostridium bacteria growing on it.

Now, on the right-hand side, we're showing you a rotten steak, and this is because it is not treated with nitrates. It is going to have growth of Clostridium botulinum on there, and so it's not going to be safe to consume. Once again, if you have high enough concentrations of these nitrates and nitrites, it helps to create that pinkish color that is associated with processed meats such as hot dogs and fresh steaks and things like that.

It is also worth noting that one of the drawbacks of using nitrates and nitrites is that they can actually be converted to nitrosamines by improper cooking or by certain gut bacteria. These nitrosamines ultimately can be carcinogenic, meaning that they can contribute to the development of cancer. Although they can be used in helping to make sure that our foods are safe to eat in terms of controlling microbial growth, at times they can also contribute to the development of cancer if they are improperly cooked or if there are specific gut bacteria that can convert these nitrates and nitrites to nitrosamines.

This here concludes our brief lesson on the use of nitrate and nitrite in food preservation, and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.

The most important function of nitrites in processed foods is to:

• A. Prevent microbes in brewing beer.
• B. Prevent carcinogen formation.
• C. Inhibits Clostridium botulinum endospores.
• D. Make the food more acidic.