Believe it or not, there is a good chance that Clostridium botulinum (aka, C. bot, as we microbiology people call it) is in your food. It is widespread in nature and found in soil and water all over the world. However, since it only grows and produces toxins in anaerobic conditions and the spores are destroyed at 250°F, the chances of you ingesting the toxin are very small. The only way to ensure that no one gets botulism is to make sure that processors are aware of how to manufacture the types of products that C. bot can grow in. If you are a food processor manufacturing low-acid or acidified canned foods, I hope that you have attended Better Process Control School (BPCS), a program that certifies supervisors of thermal processing systems, acidification and container closure for low-acid or acidified canned foods. While I don’t personally manufacture low-acid or acidified canned foods right now, as a food industry consultant I decided it was my obligation to all food consumers to bring myself up to speed on how to make these highly regulated products. 

Canning is an industry term used to describe a general method of food preservation that renders a food and the container “sterile” by using heat, alone or in combination with pH and/or water activity (aw) or other chemicals. Canned food does not just refer to food in a metal “can,” it can also be a glass jar, plastic container or laminated pouch. New packaging innovations have lead to flexible retort pouches, semi-rigid plastic containers and paperboard packages. Sterility refers specifically to the foods’ shelf stability, meaning that the product is, at room temperature, free of public health significance microorganisms. The two types of FDA-regulated canned foods, the low-acid canned foods which have a pH >4.6 and aw >0.85, and low-acid “acidified” canned food which has a pH <4.6 and aw >0.85. The most commonly used methods are conventional (high heat, high pressure), aseptic (sterile food and sterile container, lower heat) and formulation control (making sure the product is acidified or aw controlled). 

The two-day class started out with Richard H. Dougherty, Ph.D., a food science professor from Washington State University, a food processing authority and BPC instructor, telling us that botulism poisoning can happen to anyone! He cited a case in the ’70s where Campbell Soup switched out starch that resulted in a thicker texture, which reduced the heat that could penetrate the can, allowing C. bot spores to survive the retort heat treatment. This story alone made me wonder why BPSC is only a mandatory requirement for thermal process system supervisors. All food-science students should be required to take this class before graduating. That way, they understand how any change in ingredients can affect the heat penetration and spore deactivation. Any spore that survives a heat treatment and is residing in a can or low-acid food can potentially germinate, grow and produce the deadly toxin that causes botulism. 

It is a never-ending competition between man and microorganism. The microorganisms want to consume and utilize our food, breaking it down and causing it to spoil and/or become unsafe. We focus on preserving food, making it a hostile environment for microorganisms in order to prevent their survival and growth. C. bot is a spore-forming “thermophilic” (heat-loving) bacteria with spores that are very resistant to heat and only destroyed at 250°F This is why cans of food always have an overcooked or burned flavor. As an alternative to high heat, the industry will sometimes use acid in conjunction with a lower-heat treatment (165 to 212°F). The lower-heat treatment can kill all the vegetative non-spore-forming bacteria while the addition of acid (to a pH <4.6) prevents spore germination. The surviving spores will not germinate in an acidic (<4.6) environment. 

The U.S. Code of Federal Regulations has several chapters that explain, in difficult-to-understand detail, all of the rules and regulations involved in manufacturing low-acid and acidified foods. The low-acid foods are covered under 21 CFR 113 and the low-acid acidified foods are covered under 21 CFR 114. The processor of these foods has several files and forms to submit, and those details can be found in 21 CFR 108. Lastly, 21 CFR 110, entitled “Current Good Manufacturing Practice in Manufacturing, Packaging or Holding Human Food” (GMP), provides general sanitation aspects that are applicable to all food plants. 

As you can see, the manufacturing of low-acid and acidified foods is not a simple process. Luckily, the FDA explicitly states, in both 21 CFR 113 and 21 CFR 114, that the scheduled thermal process for canned foods be established by a “qualified person with expert knowledge of thermal processing requirements, acidification and processing of acidified foods”. This person is referred to as a “processing authority.” If you happen to live in the state of California, the state itself is your processing authority. Any low-acid or acidified food process has to be reviewed, by state law, by Keith Ito, the California state processing authority. If it’s OK with Keith, then the FDA is OK with it, too. 

For more information, the FDA website says it all, and then some

My trip to Washington State was not all gloom, doom and scary botulism tales. I also got to spend some time in one of my favorite cities, Seattle. After the class was over, I treated myself to a one-day whirlwind culinary tour which will be covered in my next blog!

About Rachel Zemser