What You Can (And Can’t) Safely Do With Frozen Meat

Yesterday, we asked you:

❝You have meat in the freezer. How long is it really safe to keep it?❞

…and got a range of answers, mostly indicating to a) follow the instructions (a very safe general policy) and b) do not refreeze if thawed because that would be unsafe. Fewer respondents indicated that meat could be kept for much longer than guidelines say, or conversely, that it should only be kept for weeks or less.

So, what does the science say?

Meat can be kept indefinitely (for all intents and purposes) in a freezer; it just might get tougher: True or False?

False, assuming we are talking about a normal household electrical freezer that bottoms out at about -18℃ / 0℉.

Fun fact: cryobiologists cryopreserve tissue samples (so basically, meat) at -196℃ / -320℉, and down at those temperatures, the tissues will last a lot longer than you will (and, for all practical purposes: indefinitely). There are other complications with doing so (such as getting the sample through the glass transition point without cracking it during the vitrification process) but those are beyond the scope of this article.

If you remember back to your physics or perhaps chemistry classes at school, you’ll know that molecules move more quickly at higher temperatures, and more slowly at lower ones, only approaching true stillness as they near absolute zero (-273℃ / -459℉ / 0K ← we’re not saying it’s ok, although it is; rather, that is zero kelvin; no degree sign is used with kelvins)

That means that when food is frozen, the internal processes aren’t truly paused; it’s just slowed to a point of near imperceptibility.

So, all the way up at the relatively warm temperatures of a household freezer, a lot of processes are still going on.

What this means in practical terms: those guidelines saying “keep in the freezer for up to 4 months”, “keep in the freezer for up to 9 months”, “keep in the freezer for up to 12 months” etc are being honest with you.

More or less, anyway! They’ll usually underestimate a little to be on the safe side—but so should you.

Bad things start happening within weeks at most: True or False?

False, for all practical purposes. Again, assuming a normal and properly-working household freezer as described above.

(True, technically but misleadingly: the bad things never stopped; they just slowed down to a near imperceptible pace—again, as described above)

By “bad” here we should clarify we mean “dangerous”. One subscriber wrote:

❝Meat starts losing color and flavor after being in the freezer for too long. I keep meat in the freezer for about 2 months at the most❞

…and as a matter of taste, that’s fair enough!

It is unsafe to refreeze meat that has been thawed: True or False?

False! Assuming it has otherwise been kept chilled, just the same as for fresh meat.

Food poisoning comes from bacteria, and there is nothing about the meat previously having been frozen that will make it now have more bacteria.

That means, for example…

• if it was thawed (but chilled) for a period of time, treat it like you would any other meat that has been chilled for that period of time (so probably: use it or freeze it, unless it’s been more than a few days)
• if it was thawed (and at room temperature) for a period of time, treat it like you would any other meat that has been at room temperature for that period of time (so probably: throw it out, unless the period of time is very small indeed)

The USDA gives for 2 hours max at room temperature before considering it unsalvageable, by the way.

However! Whenever you freeze meat (or almost anything with cells, really), ice crystals will form in and between cells. How much ice crystallization occurs depends on several variables, with how much water there is present in the food is usually the biggest factor (remember that animal cells are—just like us—mostly water).

Those ice crystals will damage the cell walls, causing the food to lose structural integrity. When you thaw it out, the ice crystals will disappear but the damage will be left behind (this is what “freezer burn” is).

So if your food seems a little “squishy” after having been frozen and thawed, that’s why. It’s not rotten; it’s just been stabbed countless times on a microscopic level.

The more times you freeze and thaw and refreeze food, the more this will happen. Your food will degrade in structural integrity each time, but the safety of it won’t have changed meaningfully.

Want to know more?

Further reading:

You can thaw and refreeze meat: five food safety myths busted

Take care!

Most Food Should Not Be Fuzzy

In yesterday’s newsletter, we asked you for your policy when it comes to mold on food (aside from intentional mold, e.g. blue cheese etc), and the responses were interesting:

• About 49% said “throw the whole thing away no matter what it is; it is dangerous”
• About 24% said “cut the mold off and eat the rest of whatever it is”
• The remainder were divided equally between “eat it all; keep the immune system on its toes” and “cut the mold off bread, but moldy animal products are dangerous”

So what does the science say?

Some molds are safe to eat: True or False?

True! We don’t think this is contentious so we’ll not spend much time on it, but just for the sake of being methodical: foods that are supposed to have mold on, including many kinds of cheese and even some kinds of cured meat (salami is an example; that powdery coating is mold).

We could give a big list of safe and unsafe molds, but that would be a list of names and let’s face it, they don’t introduce themselves by name.

However! The litmus test of “is it safe to eat” is:

Did you acquire it with this mold already in place and exactly as expected and advertised?

• If so, it is safe to eat (unless you have an allergy or such)
• If not, it is almost certainly not safe to eat

(more on why, later)

The “sniff test” is a good way to tell if moldy food is bad: True or False?

False. Very false. Because of how the sense of smell works.

You may feel like smell is a way of knowing about something at a distance, but the only way you can smell something is if particles of it are physically connecting with your olfactory receptors inside you. Yes, that has unfortunate implications about bathroom smells, but for now, let’s keep our attention in the kitchen.

If you sniff a moldy item of food, you will now have its mold spores inside your respiratory system. You absolutely do not want them there.

If we cut off the mold, the rest is safe to eat: True or False?

True or False, depending on what it is:

• Hard vegetables (e.g carrots, cabbage), and hard cheeses (e.g. Gruyère, Gouda) – cut off with an inch margin, and it should be safe
• Soft vegetables (e.g. tomatoes, and any vegetables that were hard but are now soft after cooking) – discard entirely; it is unsafe
• Anything else – discard entirely; it is unsafe

The reason for this is because in the case of the hard products mentioned, the mycelium roots of the mold cannot penetrate far.

In the case of the soft products mentioned, the surface mold is “the tip of the iceberg”, and the mycelium roots, which you will not usually be able to see, will penetrate the rest of it.

“Anything else” seems like quite a sweeping statement, but fruits, soft cheeses, yogurt, liquids, jams and jellies, cooked grains and pasta, meats, and yes, bread, are all things where the roots can penetrate deeply and easily. Regardless of you only being able to see a small amount, the whole thing is probably moldy.

The USDA has a handy downloadable factsheet:

Molds On Food: Are They Dangerous?

Eating a little mold is good for the immune system: True or False?

False, generally. There are of course countless types of mold, but not only are many of them pathogenic (mycotoxins), but also, a food that has mold will usually also have pathogenic bacteria along with the mold.

See for example: Occurrence, Toxicity, and Analysis of Major Mycotoxins in Food

Food poisoning will never make you healthier.

But penicillin is safe to eat: True or False?

False, and also penicillin is not the mold on your bread (or other foods).

Penicillin, an antibiotic* molecule, is produced by some species of Penicillium sp., a mold. There are hundreds of known species of Penicillium sp., and most of them are toxic, usually in multiple ways. Take for example:

Penicillium roqueforti PR toxin gene cluster characterization

*it is also not healthy to consume antibiotics unless it is seriously necessary. Antibiotics will wipe out most of your gut’s “good bacteria”, leaving you vulnerable. People have died from C. diff infections for this reason. So obviously, if you really need to take antibiotics, take them as directed, but if not, don’t.

See also: Four Ways Antibiotics Can Kill You

One last thing…

It may be that someone reading this is thinking “I’ve eaten plenty of mold, and I’m fine”. Or perhaps someone you tell about this will say that.

But there are two reasons this logic is flawed:

• Survivorship bias (like people who smoke and live to 102; we just didn’t hear from the 99.9% of people who smoke and die early)
• Being unaware of illness is not being absent of illness. Anyone who’s had an alarming diagnosis of something that started a while ago will know this, of course. It’s also possible to be “low-level ill” often and get used to it as a baseline for health. It doesn’t mean it’s not harmful for you.

Stay safe!