One of the most fascinating peculiarities about food geeks is that we are very creative. It when you have a good idea, it’s hard to hold it back. Food safety, however, sometimes may get in the way. If you have a new food that is extremely popular, both industry and consumers love it, it’s not easy to stand in the way. In some cases, the food safety issue is a very small risk of something really bad happening, and this may not sound alarming enough to convince consumers and manufacturers to pause, or maybe even regulatory authorities to act.
Cold brew coffee is one of the simplest foods you could possibly make, and full disclosure: it’s awesome and it’s becoming ever more popular. One cup of ground coffee, two or three cups of water (yeah, the stuff is really strong); steep in the fridge for 18 hours; filter it, enjoy. In terms of food safety, there is not a lot to be concerned at this point. You start with the ground beans (which were toasted, pretty much sterile) and water (luckily, most of us – still – have great water right in our faucets) which should both have very small contamination levels. You may want to boil the water if you are using a well and can’t really vouch for your filtration system. However, after the two ingredients are mixed together, any contamination will have a chance to grow if it can get in the mixture, survive the inhibitory compounds present in coffee and grow using the limited resources available and at low temperature. Unlikely? Well, never underestimate our microscopy companions. The cold never bothered Listeria monocytogenes, for instance. And we know hot brewed coffee has indeed some inhibitory compounds, but at least some lactic acid bacteria (which are not pathogens, most of them are seen as beneficial to us) can survive in that environment. It may be that pathogens will not survive and grow. The worst-case scenario at this point would be that we may need to be extra-vigilant about the good manufacturing practices (to prevent contamination) and make sure the cold brew coffee is kept refrigerated and consumed within a relatively short amount of time.
But, did I mention foodies are extremely creative?
Enter nitrogen. Different from Oxygen, Nitrogen gas (N2) is very stable. As a result, removing the air from the package and adding nitrogen already brings the benefit of slowing down the oxidation reactions that damage the delicate flavors in the coffee, a change even more noticeable in the cold brewed. But this is not the only reason why Nitrogen is added to some beers when you open the can: it turns out that, for thermodynamic reasons (a fancy way of saying I couldn’t understand it), Nitrogen makes much smaller bubbles in water solutions. The smaller bubbles take longer to separate and break down, which gives the beverage an exquisite creamy mouth feel. And there it is, after millennia after the first human being decided to roast those beautiful little fruits our civilization has finally decrypted the code for the perfect beverage. Who am I to stand in front of such accomplishment?
Problem is that it’s not me. It’s them…
Once we remove the oxygen from the package we created an environment where anaerobic bacteria, otherwise incapable of dealing with the oxidation reactions carried out by oxygen, are able to grow. I must say: luckily for us. Most of these bugs grow very slowly, are very sensitive to everything and just can’t compete for food. Still, we haven’t had a chance to be exposed to them enough to develop resistance to their tricks, and, as a result, many can cause us harm. In fact, the list of anaerobic pathogenic bacteria includes one of the most dangerous food-borne pathogens, Clostridium botulinum. You probably have heard of botulism. It’s horrible. My 9-year-old son tells me that it takes only 2.5 nanograms of botulin, the toxin produced by C. botulinum, to kill a person, and one cup could be enough to wipe out the population of the Americas. It must be true, he learned that at school.
So, am I saying that you could have died a horrible death for drinking nitro-cold brew coffee? Not so simple. C. botulinum is not (again, luckily for us) as widespread as it could be, so it probably wasn’t present in the product to begin with. And if a few spores were present they wouldn’t have been able to germinate and grow at low temperature. And yet, even if that keg of delicious cold brewed coffee was left in a hot truck for the whole day, we don’t know if they wouldn’t have been able to germinate, grow and produce the toxin. There is a possibility, however, that they would be able to do just so. Important to know too, if there were any risks of botulism in this case, they would be much higher if the product was deliberately stored at room temperature. The risk is also higher – and this may sound counter-intuitive to some – if the product is pasteurized after packaged.
The important message to be conveyed is that there is no scientific information that shows cold brew coffee is safe when kept in a reduced oxygen packaging system, such as nitrogen-infused cans. Granted, this is not the same as saying we will never learn a way to make it safe, but in doubt we must wait until we can be sure. We don’t take any risks with Clostridium botulinum.We are working on preliminary studies that will shed some light on this issue, but it may not provide the final answer that we need. And I, for one, will sadly hold on to my desire to have a refreshing bubbly coffee after lunch. Luckily, summer is over (whatever that means these days…) and a warm bulletproof coffee at 3 o’clock is not a bad idea. Join me?