When I was looking for containers to start my fermentation projects, one question that remained unanswered was if I could use a plastic container, so I just didn’t. But some time after this, I saw these questions popping up: Can you ferment kimchi in a plastic container? Can you ferment peppers in a plastic container? What about sauerkraut? So, I decided to go back to the subject and write this article with the answer.
So, can I ferment vegetables in plastic containers? You can, but not in every plastic container. You have to use plastic containers that follow the pre-requisites to make them suitable for your ferments: they have to be able to contain acidic liquid without degrading and releasing chemicals and have no scratches that would increase the danger of unhealthy bacteria being in touch with your ferments.
If thinking about using plastic, there are some categories you should keep an eye on to make sure you find a durable container that is safe for you and our precious, healthy bacteria.
What is The Problem With Plastic Containers for Fermentation?
There are 3 main concerns when using a plastic container:
- The acidic environment
- Scratches inside it can harbor unwanted bacteria
I will get into detail about each of them to help you understand the problem and, later, I will tell you the solution. If you are already aware of it, scroll to the next topic.
The first problem (not in order of importance) is the pH level of the ferments. During fermentation, the lactic acid bacteria will produce lactic acid, turning the environment acidic. That is a good thing because this is how the fermentation process protects the food from mold and spoilage bacteria.
On the other hand, some materials will react with the acid or be corroded by it. This is the case with many plastics and acidic food. And if you use a plastic that is not resistant to acid, it can release chemical products on your food. We definitely do not want that!
The second problem is that plastic containers can easily be scratched inside, which could harbor unwanted bacteria that will end up being in touch with your fermented vegetables.
Even thin and small scratches can harbor enough bacteria to spoil your vegetables or make you sick. Bacteria are microbes, which means really, really, really small. So, you would be taking a blind and unmeasurable risk to use a scratched plastic container. No pun intended.
And third, but not least. BPA. You probably have heard of it many times so I won’t get into too many details, but here is the basic you need to know to understand this problem.
BPA stands for bisphenol A. BPA is an industrial chemical that has been used to make certain plastics and resins since the 1960s. […] Some research has shown that BPA can seep into food or beverages from containers that are made with BPA. Exposure to BPA is a concern because of possible health effects of BPA on the brain and prostate gland of fetuses, infants and children. It can also affect children’s behavior. Additional research suggests a possible link between BPA and increased blood pressure.Mayo Clinic about BPA
This means BPA is bad, even though it is legal and it is pretty cheap. Consequently, many plastic products (and non-plastic products, like soda cans) have BPA in their composition. You definitely shouldn’t ferment your vegetables in a container with BPA!
Which Plastics Containers CAN I Use to Ferment Vegetables?
We have already talked about the problems with plastic containers. However, as I said before, there are plastic containers that are suitable for fermentation.
In addition to being BPA-free and having no scratches inside, as mentioned before, here’s what you need to know:
The plastic containers must be able to contain the acidic liquid
The many kinds of plastic that exist are divided into categories to assist both you and companies in making this choice. The FDA (US Food and Drug Administration, a federal agency of the United States Department of Health and Human Services) is one of the organs that regulated the plastics used for food packaging and food handling. Even though this can vary between countries, the norms and symbols are very much alike. For the purpose of this article, we will be looking into “Food Grade,” “Food Safe,” and “FDA Compliant” plastics.
FDA Compliant plastics follow the rules this governmental organ stipulated as essential for plastics that are in direct contact with food.
FDA compliant is a shorthand way of talking about materials that are safe for direct food contact. These materials are also called food contact substances (FCS). An FCS is any material that comes into contact with or is used for manufacturing, packing, packaging, transporting, or holding food. Both the plastics and the pigments used in making colored plastic fittings and cooking utensils are examples of food-contact substances.ISM Website
For a plastic to be FDA Compliant, it has to also be Food Grade and Food Safe.
Food grade means that the material is either safe for human consumption or it is okay to come into direct contact with food products.
Food safe means that a food-grade material is also suitable for its intended use and will not create a food-safety hazard.ISM Website
A little reminder is that the plastic is only considered food grade/safe if it is being used for the purpose it was intended to. For example, an ice cream container is supposed to be used in cold temperatures for non-acidic food. So, it won’t be considered food safe for hot soup.
This way, it would not be safe to pour piping hot soup into an ice cream tub. As you can imagine, the tub could melt, or slowly degrade, releasing the layers of all products used to make it safe for cold foods. The same happens with your ferments if you use the wrong kind of container.
If you want to ferment in a plastic container, just make sure it is a Food Grade Plastic, is BPA-free, and was made to retain acidic liquids. There are buckets made for drinks fermentation (like beer and wine) that would be suitable for kimchi or any other vegetable fermentation.
How to Know if a Container is Food Grade Plastic?
The easiest way to know if a container is BPA-free is to check its description or ask the seller. However, this might only work if you are buying a new one. Now, if you want to check a container you already have in your home, look for the recycling symbol on the bottom of it, this way, you will know from which kind of plastic is the container made.
The recycling symbol is a triangle with a number inside that corresponds to the type of plastic. The number between 1 and 7 are in the food-grade range.
|1||Polyethylene Terephthalate (PET or PETE)||Use with Caution|
|2||High-Density Polyethylene (HDPE)||Safest Choice|
|3||Polyvinyl Chloride (PVC)||Avoid|
|4||Low-Density Polyethylene (LDPE)||Safest Choice|
|5||Polypropylene (PP)||Safest Choice|
|7||Miscellaneous Plastics |
(polycarbonate, polyctide, acrylic, acrylonitrile butadiene, styrene, fiberglass, and nylon)
|Use with Caution|
However, even if the plastic belongs to one of the categories above, you still have to check if the container is Food Safe since it could have been used to store a chemical product, like cleaning products, which would contaminate the food. The symbol for food-safe plastic is a wine glass and a fork. Check for this symbol, to know if the container was made to be in direct contact with food.
Now, the only thing left to check is if the Container is BPA-free. So, How to find out if a container is BPA-Free? Normally, if the symbol in the triangle is not 7 and the plastic is not clear or (clear-tinted), you can suppose it is BPA-free. Otherwise, you have to check with the manufacture.
To recap, vegetable fermentation produces lactic acid that can react with some plastics releasing chemicals and/or BPA. Plastic containers can also have scratches inside, which can become a depository for bacteria that could endanger your fermentation. On the flip side, when doing bigger batches, you might have a hard time finding a glass container of the appropriate size, and plastic might be the only solution. In this case, you should guarantee the container is the best one available.