Curing bacon with a wet brine, without nitrates

Question

When making bacon, many of the recipes call for a dry brine using curing salt with nitrates. I've read that it is possible to use a wet brine without the curing salt with the nitrates and just use Kosher salt (or some other salt). Is this possible and safe to use just kosher salt and water? From my understanding curing salt with nitrates can be toxic, but also protects against botulism but I'm still looking for a safer alternative.

Answer

Salt inhibits bacterial growth mainly by drawing moisture out of the meat. A wet cure (brine) would be substantially less effective at this than a dry cure, unless you add much more salt to your brine and, also, you take the extra step of drying the meat afterwards. Besides, the texture of the final product is likely to be substantially different, possibly not in a good way.

As you alluded, potassium nitrate (a/k/a saltpeter) is used in cures because, strangely, it does indeed stop the growth of Clostridium botulinum, the bacteria that causes botulism. Other salt cures do not have this property, which might explain why some recipes call for adding a little powdered ascorbic acid to the salt. Hopefully, however, you are not planning to leave your bacon in a vacuum-sealed bag at room temperature, so this should not be a major factor in which cure recipe you use. I would be far more concerned about generating carcinogenic nitrosamines from frying nitrate-laden meat.

For extensive discussions, see the USDA/FSIS bacon fact sheet and the University of Georgia smoke-cure fact page, as well as the University of Minnesota's fact page on nitrites.

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How long does it take botulism spores to germinate in the fridge?

Question

Based on this question, I started wondering how long I could keep an anerobic food in the fridge before I have to worry about botulism colonization. 1 day? 3 days? 2 months? Clearly it's not a short period of time (hours) or we'd all be dying of botulism poisoning by now.

Unfortunately, nothing I've been able to find on the net seems to be based on solid studies of germination times. So, if I put a pre-prepared sous vide packet in the fridge, or homemade garlic oil, a low-acid sauce, or lemon curd, or similar, when do I have to toss it to be safe?

Answer

This completely depends on all of the other factors involved in botulinum growth, not to mention the particular strain you're concerned about (there are several).

Salt, acidity (low pH), low moisture, and extreme temperature (low or high) will all slow botulinum growth significantly.

There are proteolytic and non-proteolytic types of bacteria. The non-proteolytic C.botulinum bacteria will never grow in the refrigerator - they cannot grow at temperatures below 12° C ^source. The proteolytic strains can grow at temperatures as low as 3° C. That is very close to refrigerator temperature so clearly they will grow very slowly - again, the exact speed depends on other factors - but they will grow.

According to other sources, the proteolytic strains (the ones that can grow in the fridge) are the ones that tend to produce gas and off-odours, so they'll be more easily detectable. They also have far lower heat resistance, so they are easier to cook away. But of course, if they've grown to a sufficient level, it's too late to do that.

As far as I know, there aren't specific guidelines for vacuum-packed foods, whether commercially packed or simply cooked sous-vide. I'd ask you to consider that botulism is not the only type of foodborne illness that can grow in the refrigerator. There's also listeria, salmonella, and possibly some others I'm forgetting about. Cooking (especially sous-vide cooking) doesn't kill every last one of them, just enough to make the food safe. By the way, listeria and salmonella are both facultative anaerobes which means that they can grow with or without air.

There's also the small matter of your actual refrigerator temperature. Although the theoretical temperature (4° C) is lower than that required for all but the hardiest of bacteria, once you move up even a single degree to 5° C there are many more kinds that can start to grow. How cold is your fridge, really? I've heard of some being as high as 10-12° C in parts! If your fridge temperature is even slightly high, botulism will be the least of your worries.

Honestly, given the incredibly tiny number of actual documented cases of botulism (less than a dozen per year in the U.S.) compared to the insanely high total number of food poisoning cases every year (1 in 4 according to some sources), people seem to place far too much emphasis on that particular species. I realize that it's one of the scariest on account of that whole "instant death" thing, but even if you could prove that your improperly-stored food is 100% free of botulism toxin, you could still get seriously ill from eating it. You're literally worrying about the least probable vector for food poisoning.

Bottom line, I'd strongly advise you to treat sous-vide food just like any other food in terms of food safety and freeze it if you plan to store it longer than 4-5 days. There are just too many variables at play to conclusively say otherwise.

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