What temperature do I REALLY have to reheat food to for safety?
April 28, 2020 10:55 AM   Subscribe

So I'm having trouble finding information on this other than from various countries' official food safety recommendations, which are notoriously over-cautious and would have us all eating steaks like hockey-pucks and pork chops like packing material if strictly followed.

Where I am in the UK the rules say that if you're a business then it has to be 75°C in England or 82°C in Scotland (the discrepancy reassuring me that this is based on sound science), but I'm not a business and I'd never let chicken get over 65°C when cooking from raw, so are these regulations just the same level of over-cautious? Is there something when re-heating food which means I should shoot higher than cooking from fresh? Is it different depending on what the food to be reheated is?

Assumptions for the sake of this question:

1. I'll not be using a method which, wherever the temperature ends up, involves the food hanging out in the "danger zone" for a long time due to reheating slowly.
2. The food in question was securely air-tight sealed and frozen almost immediately after first being cooked.
posted by Dext to Food & Drink (5 answers total) 2 users marked this as a favorite
Cooking meat to safety is completely different than reheating leftovers.

Heating leftovers to high heat can help turn something from questionable to safe.

But good leftovers don’t even need to be reheated at all. Yesterdays’s spaghetti is perfectly safe cold, if it’s been handled and stored properly. Cold pizza for breakfast, etc etc.

Properly frozen food only needs to be thawed until you can eat it.

I’m not sure why you’d think frozen food has to reach some minimum temp like raw chicken does in order to be safe for consumption. It does not. Frozen food can’t even really go bad over time in terms of safety, though it can suffer from freezer burn and become less tasty.
posted by SaltySalticid at 11:03 AM on April 28, 2020 [3 favorites]

Best answer: Pasteurization is a function of time and heat. 75/82C is where 1 second at that time pasteurizes a food. Will you be reheating it sealed (e.g., sous vide or simmer-in-a-bag)? If so, you're good to go -- just heat to serving temp. Reheating is a quality function, not a safety one.

There's a nice chart (albeit in our silly American units) in this article showing temp v. time for pasteurization.
posted by bfranklin at 11:07 AM on April 28, 2020 [6 favorites]

Many frozen meals are sold partially cooked. In those cases, the reheating temperatures are going to be consistent with any other cooking temperatures.

For fully cooked frozen foods, the majority of the regulations for reheating frozen food are to avoid partially reheating frozen food. For instance, if you took out some fully cooked chicken, put it in some lukewarm water, heated it to 40°C, and left it for two hours, you'd be growing a whole lot of bacteria on that chicken. You indicate you won't do that with your 1) consideration, but regulations are intended to prevent scenarios for that.
posted by saeculorum at 11:10 AM on April 28, 2020 [2 favorites]

Response by poster: Brilliant, thanks to all, the general concept being espoused that if your food was safe to eat when you froze it and then you don't let it hang in the danger zone while reheating makes perfect sense - think I just got scared by reading governemtn recommendations and remembering, from when I used to eat ready-meals, strict instructions to reheat to "piping hot".

Particular thanks to bfranklin: Yes, lacking a microwave but having a vacuum sealer I'm reheating sous-vide so that's exactly what I wanted to hear. Also I had a vague memory of that pasteurisation chart and was thinking of it but couldn't work out the right Google-fu to find it again so that's much appreciated.
posted by Dext at 11:27 AM on April 28, 2020 [1 favorite]

Here are a good set of charts to reinforce what bfranklin posted.
posted by JoeZydeco at 12:41 PM on April 28, 2020 [2 favorites]

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