Issue #79 | Botulism: the Putin of pathogens | Cacao or Cocoa - what's the difference | DNA barcoding for food testing |
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Remarkable botulism, the Putin of food pathogens
You say cacao, I say cocoa
Celebrating 20 years of DNA barcoding
Past issues compilation out now for paying subscribers
News and Resources Roundup
Food fraud news, incidents and updates
Welcome to Issue 79 where I indulge my ghoulish fascination with one of the super-stars of food pathogens: Clostridium botulinum. I had a wonderful time writing that story this morning, I hope you enjoy reading it.
Also this week, a short piece about cocoa (or is it cacao?) and a celebration of DNA barcoding, a test method for food safety and food fraud analyses.
This week I’m pleased to offer paying subscribers a new e-book which contains Issues 51 to 75 in a downloadable, printable version for your offline reading pleasure.
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As always I’ve got a hand-curated selection of food safety news and resources for everyone and food fraud news for paying subscribers, plus an 🎧 audio version 🎧 so you can catch up while on the go (find that below the paywall).
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Cover image: Don Fontijn on Unsplash
Erratum: The original version of this Issue had an error about botulinum toxin. It is NOT heat stable (phew).
Remarkable Botulism – the Putin of food pathogens
Botulism – a deadly foodborne illness – made an unexpected appearance in plant-based milk last month. And it sent a chill through the food safety community.
Botulism is deadly
Botulism is possibly the scariest food-borne illness there is. And I for one would NOT want to get it.
Here’s what happens to you if you are unlucky enough to eat food that contains the toxin that causes botulism, botulinum toxin.
A few hours to a few days after eating heavily contaminated food you start experiencing neurological symptoms that include blurred vision, difficulty speaking and swallowing, then paralysis. If you don’t get medical help quickly the toxin paralyses your heart and lungs and you experience respiratory failure and then death (source).
The friend of a victim described the final two months of his life before he succumbed to the disease as follows: “He could not move, he couldn’t talk, he couldn’t breathe, but he was conscious and aware and could understand and somewhat able to communicate,” (source)
The good news is that there are antitoxins and in the United States, the fatality rate is around five percent (source).
The bad news is that the antitoxins do not reverse paralysis but just stop it from progressing. Recovery depends on your body regenerating new nerve connections and patients may need to be on ventilators for weeks or months. Survivors can experience fatigue and shortness of breath for years (source).
You only need a tiny amount of toxin to cause life-threatening symptoms. In fact, one teaspoon of the toxin contains enough to kill more than 70 million people. (This is based on a lethal dose of 70 nanograms for a 70 kg adult).
Botulism is an ever-present risk
Botulism is rare, but it’s surprisingly easy to create an outbreak by disregarding food safety practices.
Botulism, the disease, is caused by botulinum toxin getting into people. Usually, it gets in when someone eats food that contains the toxin. Less commonly, the toxin forms inside people.
The toxin is produced when Clostridium botulinum bacteria grow and reproduce in food or inside people’s intestines, which occurs with infant botulism or inside deep wounds.
The C. botulinum bacterium is everywhere. Or, more correctly, its spores are everywhere (microbiologists call them ‘ubiquitous’). I have fond memories of a laboratory assignment from my second year of university. My lab partner and I were given the task of finding C. botulinum, isolating it and identifying it using traditional micro/chemical tests. We ducked outside the microbiology lab and grabbed a handful of dirt from the garden under the window to culture. We found C. botulinum on our first attempt. (I also remember a class-mate swabbing his crotch to obtain Streptococcus 😊)
Botulinum toxin is a covert operator
Botulinum toxin is not just super super toxic. It is also colourless and tasteless in food – at least in the concentrations that occur naturally. So you won’t know if it is in the food you are eating until it is much too late.
The botulism pathogen is tough
The spores of C. botulinum can survive heat, cold and dehydration and remain viable for decades. When they are exposed to the correct conditions they germinate and grow into colonies of live bacteria, producing toxin in the process.
To protect food from botulinum toxin contamination, then, we must prevent the bacteria from reproducing in food. Because C. botulinum is ‘ubiquitous’, food safety controls are based on the assumption that all raw food could carry its spores. Only one spore is needed for the pathogen to grow and form toxin. So, to prevent such growth we have two types of ‘weapons’:
(1) Treat the food with extreme heat to deactivate C. botulinum spores so they cannot grow and produce toxin.
(2) Ensure the food is too acidic or too cold or too dry or too salty or too well-oxygenated to support the growth of the bacterium, even though its spores are present.
Fighting the pathogen
Commercial food canning processes and the sterilisation of medical equipment work by deactivating C. botulinum spores with heat. The process requires exposure to at least 121 degrees C for more than three minutes.
Because most food contains a lot of water and because water cannot reach temperatures greater than 100 degrees at normal air pressure, achieving temperatures of 121 degrees can be a challenge. One way to reach 121 degrees is to use high pressure conditions, by heating the food inside a sealed can, jar, pouch, pressure cooker, autoclave machine or retort.
Other food protection methods rely on a combination of conditions that prevent the spores from germinating, such as cold, acid or oxygen. This is sometimes described as a combination of ‘hurdles’. For example, fresh milk is safe from botulinum contamination because it has oxygen in the pack and is stored in the refrigerator – two hurdles. Home preserved fruit, and pickles, which can be low in oxygen while the jar is unopened, have the benefit of being too acidic for C. botulinum spores to grow.
When foods are not acidic – food safety experts call them ‘low-acid foods’ – and are also stored at room temperature without oxygen they could support the growth of C. botulinum. Food with low oxygen includes foods in cans, jars, bottles and pouches and foods immersed in oil. This is why low-acid canned foods are considered very high-risk foods.
Examples of high-risk foods include canned vegetables, fermented meats like salami, preserved vegetables like beans, mushrooms or garlic, low-acid-not-chilled drinks like cold brew coffee and vegetables like garlic stored under oil.
Vigilance is needed
The plant-based milk that caused botulism last month in Australia turned out to have been missing vital (and legally required) storage information on the pack. Authorities said the product’s labels did not state that it needed to be kept refrigerated. The product is sold chilled and is not suitable for storing at room temperature.
Investigators found botulinum toxin in the product and believe it had been stored at room temperature instead of in the refrigerator. The combination of the low-acid liquid, a closed container and room-temperature storage would have supported the growth of C. botulinum – growth that would not have occurred if the product had been stored in the fridge.
This event proves just how easy it is for a simple mistake to cause potentially deadly illnesses.
Other recent examples of botulism include two deaths from homemade sausages in Argentina, and multiple outbreaks in Italy including cases linked to preserved olives, pesto and tuna. The man whose friend I quoted at the beginning of this article and who spent two months paralysed before dying of botulism last year is thought to have eaten un-refrigerated soup from an open or damaged can while on a solo wilderness expedition.
Home canned low-acid foods are at high risk of botulism because it is easy to make a mistake with the time/temperature/acid hurdle combinations needed to keep the food safe.
Food safety authorities impose licensing restrictions and rules on commercial low-acid food preservation activities and will urgently recall products if they discover that a food manufacturer has not properly controlled the temperature of a canning or bottling process. Examples include a recall for soft cheese in jars of oil and chai drink sold in glass bottles in 2022.
A new war is coming?
There are increasing calls for governments to outlaw the use of nitrite preservatives in processed meats, due to their links to cancer. Traditionally, nitrites were added to processed and fermented meats to prevent C. botulinum growth. Now, some scientists are arguing that nitrites do not work as a ‘hurdle’ for botulism control and their cancer risks outweigh any botulism risk.
If nitrites are outlawed, we might have one less weapon in the fight against this deadly pathogen.
🍏 Botulism is a potentially deadly foodborne illness with horrible symptoms 🍏 It is rare but also surprisingly easy to cause 🍏 The pathogen is a spore-forming bacterium whose spores are very tough and are found throughout the natural environment 🍏 Recent outbreaks and recalls remind us of the importance of robust control systems and the dangers of home preservation techniques 🍏 A ban on nitrites might increase the risk of botulism from fermented and preserved meats, though more research is needed 🍏
You say Cacao, I say Cocoa
A group of thirty professionals from the chocolate industry, including researchers and scholars, have spent 12 months creating a Chocolate Glossary which offers definitions of terms used in the fine chocolate industry, and illustrates how those terms are used in the real world.
One key challenge in fine chocolate is varying understandings for how the words cocoa and cacao are used. For example, one academic says she refers to all products of Theobroma cacao as ‘cocoa’, regardless of their level of processing, but other people use ‘cocoa’ for a subset of processed products.
Cacao – as defined in the Fine Chocolate Glossary
“In the Anglophone context, “cocoa” is used commonly in reference to the tree and the seed and especially as a referent for the commodity onice it has been sold or processed….. The word “cacao”, [however], is symbolically important… many see it as a… point of distinction from bulk commodity cocoa.”
Read more about the development of the glossary, or listen to a podcast episode about the establishment of the glossary: https://www.confectionerynews.com/Article/2023/02/20/FCIA-launches-Fine-Chocolate-Glossary
Cocoa and food fraud
Cocoa is at medium risk of food fraud because it has complex supply chains, volatile prices and global production challenges due to climate change. Cocoa that is claimed to be organic, fair trade or ethically or sustainably sourced is most at risk of fraud (source).
Cocoa from Ghana (35 tonnes) and sugar were among a large quantity of prohibited products that were incinerated by customs officials after an anti-smuggling operation in Cote d'Ivoire in December.
In 2021 Hershey and the Rainforest Alliance were sued for false advertising in the US, because of the prevalence of child labour in the supply chain and the fact that the certification scheme doesn’t seem to prevent it.
In Issue 13 we explored the challenges with ethical chocolate certifications like Rainforest Alliance and concluded that they provide only very limited protections for forced labour, child labour and other modern slavery practices in cocoa supply chains.
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The e-book is a compilation of issues 51 to 75 of this newsletter, in a downloadable, printable format.
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Celebrating 20 years of DNA barcoding
It is twenty years since Dr. Paul Hebert at the University of Guelph in Canada developed the DNA barcoding method for identifying and classifying organisms (source). Since then it has become a powerful tool for food safety and food fraud investigations and research.
So what is DNA barcoding exactly and what does it mean for food professionals?
DNA barcoding is a method for identifying different species of organisms using a short, standardised segment of DNA. It's kind of like scanning a barcode on a product in the supermarket to look up its identity, but instead of a barcode, scientists use a specific part of an organism's DNA.
DNA barcoding is useful for identifying species that look very similar or are difficult to classify. For example, if you're trying to identify two different species of fish that look almost identical, you could extract DNA from each fish and compare the DNA barcodes to see if they match or not.
In food safety, it can be used for pathogen surveillance, environmental sampling and outbreak investigations. In food fraud, it is used to confirm the source or species of food ingredients or products, such as by testing seafood samples to see if the labelled species is correct, or if the fish has been substituted with a cheaper species.
The advantage of DNA barcoding as an analytical method is that you can get reliable information about identity without having to ‘read’ every single gene in an organism’s genome. For example, a human’s genome has seven billion base pairs (components of DNA), but you can distinguish human DNA from all other species by choosing to ‘read’ just 600 base pairs (source).
Because DNA barcoding methods only ‘look’ for a small number of standardised DNA markers, which can be amplified and sequenced relatively quickly, they can be less expensive than other DNA methods, especially for large-scale surveys.
In contrast, whole genome sequencing, which is also used for food safety and food fraud investigations, involves analysing the entire DNA sequence of an organism, which is much more complex and expensive than DNA barcoding. However, whole genome sequencing provides more information beyond species identification, such as genetic variations, virulence genes, and evolutionary relationships.
DNA barcoding in food fraud investigations
Examples of food fraud activities involving DNA barcoding methods include:
a sausage survey that found 14 percent of samples contained meat that wasn’t listed on the label,
shark fins for soup that turned out to be from protected and threatened species,
and mislabelling of fish products with respect to their species, at a rate of 15% in Canada.
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News and Resources
Click the link below for this week’s food safety news and resources from around the globe. (Heaps of good free online training this week).
What you missed in last week’s issue
Glyphosate (not) as safe as table salt (oh Monsanto!)
Datasets for the American Food System
Fake Food, Japanese Style (Just for Fun)
Food fraud incidents, updates and emerging issues - including an unexpected new issue for beef
Below for paying subscribers: Food fraud news and incident reports, plus an 🎧 audio version 🎧 so you can catch up while on the go
📌 Food Fraud News 📌
Every year, the Canadian government tests a selection of foods for food fraud.
This year, they added meat for the first time, and found
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