Why can’t you heat up spoiled food to rid it of bacteria?

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I’m talking things where harmful bacteria grows on it if you leave it out too long. Like, I’m apparently not supposed to eat leftover rice that’s been left out too long cause bacteria grows on it. If I were to heat up the rice enough, wouldn’t that kill the bacteria?

In: Biology

5 Answers

Anonymous 0 Comments

> If I were to heat up the rice enough, wouldn’t that kill the bacteria?

You can, heating food up to sufficiently high temperature for long enough will definitely kill all the bacteria.

However, that doesn’t make spoiled food safe to eat. Food spoils because the bacteria eats the food and poops out poisonous wastes. Those poisons are still poisons even when heated. They are just hot poison. Cooking it isn’t going to turn the poison back into food. You will just be eating dead bacteria and poison.

Anonymous 0 Comments

Because bacteria poop, and bacteria die. Their bodies and their waste are still in the food even if the colonies are dead.

Anonymous 0 Comments

Bacteria also release toxins which are not destroyed by heating food up (think of it as bacteria poop) https://youtu.be/9aPZGF4gQag

Anonymous 0 Comments

People have already mentioned bacteria-produced toxins that may not be affected by the heat treatment.

But I think the main point hasn’t been mentioned yet: you likely will not be reheating all your food to a high enough temperature and holding it at that temperature for long enough to ensure the bacteria (and other bio-contaminants) are dead.

Where I work, we have sterilization and pasteurization processes on our food-grade product, at different stages of the process. Sterilization for us requires heating the material uniformly to >121C and holding that for an hour. This *should* kill anything that might be present. Note that it’s substantially higher than boiling, which in turn is higher than cooking temperatures reached for many meals, which in turn is higher than typical reheating temperatures.

Pasteurization, in our case, is intended to kill active/vegetative bacteria, while leaving probiotic spores alive/viable. That temperature is 65C, for 30 minutes. But if our product was contaminated with other spore-producing bacteria (like B. Cereus), and we relied on just pasteurization, then those dangerous spores would have a chance to reactivate.

Many products have pasteurization protocols, like milk, and often you can choose between lower temperatures for a longer time vs higher ones for a shorter time. But it doesn’t solve everything, and neither does reheating. Reaching and holding boiling temperature will likely ruin your meal from an enjoyability/edibility perspective, and that’s still not enough to kill everything.

Anonymous 0 Comments

Some foods develop endospores which grow into toxin-producing bacteria, and are extremely heat resistant and can make you very very ill.