Some fun information below applies mainly to house-made Reduced Oxygen Packaging (ROP). ROP can only be done with an approved HACCP plan, which outlines strict controls to prevent the germination and/or outgrowth of facultative and strict anaerobic bacteria, especially Clostridium Botulinum, commonly called C. bot.
I’ve summarized some texts here with the intent to write a condensed reference for C. bot. The NYC Dept of Health sets forth strict time & temperature requirements for ROP, and sets the time/temp requirement for seafood at 320F (“frozen/on ice”) and 72 hours maximum in ROP. Other time/temp parameters vary according to protein & preparation.
When we reference C. bot, we are actually talking about a dormant spore-forming bacterium that is, by itself, not harmful to humans while it is in the presence of oxygen (which is why it’s typically an issue with home-canning, fermentation, or preserving, all of which often done without knowledge of proper controls). C. bot grows without oxygen, and produces toxins that are some of the deadliest known to man—7 million times stronger than cobra venom. Just a bit of that (less than 1 nanogram) will cause botulism. A pinch more will kill… the median lethal dose is 1.3 to 2.1 nanograms. How much toxin is that, exactly? Well, by weight, a single poppy seed weighs 300,000 nanograms.
In the presence of oxygen, C. botulinum is usually killed off by competing “friendly” bacteria. However, in the anaerobic environment created by ROP, the competing bacteria (which thrive on oxygen) die off, thereby stopping any competition and allowing C bot to roar to life. When exposed to oxygen, vegetative C bot sporulate, which allows them to form many layers (an armor, if you will), resistant to heat, pressure, and cold. Take away oxygen, and C bot germinates, metabolizing quickly, and go on to create at least 7 different toxins, three of which are neurotoxins.
It should be noted that C. botlulinum only needs a layer of fat to seal out oxygen so that it may germinate. This is what makes the bacterium such a threat in un-eviscerated fish. Usually, if C. botulinum is germinating in an oxygenated environment, then so too are stinky, color-changing microorganisms, which then create the kind of gut-churning smells of spoiled food. Food is discarded regardless of whether vegetative C bot has created any toxins in anaerobic portions of the
product.
But without other competing “friendly” bacteria to supply the telltale signs of spoilage, product from beef to cheese to seafood in ROP will not smell or look “bad”, it could simply become lethally poisonous. Fish & aquatic animals are slightly different: in addition to always needing to be processed & cryovacked at or below freezing, sometimes you’ll get “off” odors or colors. Because botulism toxins are typically undetectable, you should always rely on time & temperature controls for your ROP product, and not rely on sensory information such as smell, appearance, or taste. Many consumer packaged goods manufacturers rely on Time / Temperature Indicators (TTIs) which trace the Skinner/Larkin Curve for C. bot. But most manufacturers don’t, and I personally have never seen a restaurant or small manufacturer deploy TTIs on vacuum-packaged ROP product.
Ultra-rapid (blast-chill) or slow freezing does not destroy C. botulinum spores, and it will not inactivate the toxins. When thawing frozen ROP product, any heat between 40 – 120 degrees Fahrenheit can activate the spores’ germination, causing new toxins to be manufactured. In fact, a Journal of Infectious Diseases study in 1933 demonstrated C. botulinum to be capable of surviving eight repeated freezings & thawings!
Once the toxin is manufactured, the only way to inactivate it is to heat the product to 1760F for 20 minutes or 1850F for at least 5 minutes. Not very practical, which is why prevention (monitoring time/temperature and storage conditions of ROP product) should always be your focus.
Botulinum bacteria occur as both bacterium and spores in soils, marine sediments, in the intestinal tracts of mammals and fish, and in the gills & viscera of shellfish (such as crabs).
In humans, botulism begins in the lower intestines, where the toxin is absorbed into the bloodstream between 12 and 36 hours after food was ingested (and can appear as late as 10 days after ingestion). The toxin circulates and blocks myoneural junctions, seizing motor nerve terminals by stopping the release of acetylcholine, which in turn halts nerve-muscle communication. Weakness, vomiting, and malaise are the initial onset; later, the face droops and paralysis begins from the shoulders down. Botulism deaths usually result from asphyxia due to lung paralysis.
The only treatment for botulism is a targeted anti-toxin, which is administered exclusively through the Centers for Disease Control (CDC). The CDC then begins an investigation into the source of the C bot. I, for one, don’t want to be on the receiving end of that investigation! So mind your HACCP plan, Chefs! And thanks for reading.
To learn more about how you can avoid cooling violations at your next restaurant inspection, visit Bulletproof! Food Safety’s website.
