The difference in animal fat, seed oils and olive oil in health and cooking

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My question comes from a place seeking less waste while maintaining food-safe ways of reusing appropriate fat types. I am coming from a place of poor food science knowledge, so please be patient!

I hear of southern folk in the states saving bacon grease and cooking with it and I agree it has great flavour, but.

1) Are grandmothers who store bacon fat at room temperature simply exposing themselves to unseen bacteria growth?
2) What about using bacon to season cast iron pans? Does high heat simply “cook off” bacteria on greased surfaces that have been exposed to air a long time?

3) Do animal fat and oils both get trapped in our bodies the same way as subcutaneous fat?
4) And does eating bacon grease of a poorly fed or sick animal affect us in anyway? Or this would all bypass the animal’s (removed) digestive tract and not necessarily be consumed by humans later? Thinking of heavy metals and pesticides, for example.

The internet says seed oils are high in polyunsaturated fats and are can turn toxic at high temperatures. This is supposedly bad for you. A lot of picked Italian products are preserved in oil.

6) When I’m done with a commercial jar [(canola oil for example)](https://images.app.goo.gl/FizK1wQwodKNJttY7), is it a safe idea to re-use the oil for cooking?

7) Does the presence of previously preserved food remnants start a bacteria growth process and this jar of used (but uncooked) oil should be discarded?

Olive oil is touted as the healthiest oil to cook with…

8) Is this a marketing gimmick? Chefs advise to avoided cooking with olive oil at high temperatures, but it seems like an oxymoron to me as you would think to use high temperature to kill bacteria on chicken etc.

In: 12

I can answer number 2 and 8. Oils have a certain burning point. Bacon grease has a low burning point so not good for cast iron pans because it would just burn and taste bad. Olive oil has a low burning point too but not as low as bacon grease. You can use olive oil for cooking at lower temps but I wouldn’t use it for higher temps.

Avocado oil and coconut oil have very high burning points

> Are grandmothers who store bacon fat at room temperature simply exposing themselves to unseen bacteria growth?

No. One, it’s sterile (they’re putting it in the jar at like 250 degrees or so.) Two, there’s nowhere near enough moisture for bacterial growth, and it’s kind of salty (because bacon is salty.) In fact you can preserve foods by packing them in oil or fat – if you’re familiar with brining, this is kind of the same thing, only with fat. (In French, this is called a *confit.*)

The concern with room-temperature storage of bacon grease is that it eventually goes rancid, which is when unsaturated fats are attacked by UV light and oxygen and develop a bad taste. But bacon fat, like most animal fats, is a highly saturated fat so its relatively resistant to rancidity. You can avoid rancidity by covering it and storing it in the dark, cool environment of your refrigerator.

> Do animal fat and oils both get trapped in our bodies the same way as subcutaneous fat?

Subcutaneous fat, like all your body’s fat tissue, is produced by your body *from* your diet; it’s not harvested from your diet. Fat doesn’t make you fat. There are only two essential dietary fats (fats your body can’t produce) but they’re mostly in your blood and are part of your energy metabolism.

> Thinking of heavy metals and pesticides, for example.

Different toxins accumulate in the body (and are removed from it) at different rates and in different tissues. Toxins that accumulate in fat are generally removed very slowly (since they’re typically not readily dissolved in blood) and if you eat the fat of an animal that has a lot of such toxins, you can expect those toxins to accumulate in *your* body as well. You can imagine how certain pollutants might accumulate “up the food chain” as a result of animals eating animals that eat other animals, and this mechanism is called “bioaccumulation” and it’s one of the reasons DDT was so unexpectedly harmful to predatory birds.

> When I’m done with a commercial jar (canola oil for example), is it a safe idea to re-use the oil for cooking?

I wouldn’t cook with packing oils, personally. Not because it’s unsafe but because they’ll likely contain a lot of food particles that will scorch – it’ll just taste bad. What you want in a cooking oil is clarity and purity, for a high smoke point.

If you’re looking for some way to recycle oils used to can or pack or preserve foods, you could look into soapmaking and make castille soaps. I’m not sure anyone wants a soap made from a can of sardines, though.

>Are grandmothers who store bacon fat at room temperature simply exposing themselves to unseen bacteria growth?
>
>What about using bacon to season cast iron pans? Does high heat simply “cook off” bacteria on greased surfaces that have been exposed to air a long time?

Fat is not especially good for growth of bacteria and fungus, which mostly want water and sugar. Most also want oxygen, which fat will tend to block access to.

Bacon during cooking and cast iron pans during seasoning are heated hot enough to kill basically most bacteria or fungus that can grow at room temperature, and thus is effectively sterilized, and those same temperatures will remove any water that might contaminate it.

Overall, there is extremely little risk of illness from it, unless/until the fat becomes contaminated with enough water and sugar. Keeping it covered during storage should keep water levels low enough to keep it safe.

Most of the problem with storage of fats is it going rancid by combining with oxygen. Rancid fat is still safe to eat, but tastes terrible – likely as an evolutionary adaptation to keep us from eating rotten meat. Again, keeping it covered will minimize oxygen contact, minimizing the risk of the fat going rancid.

>Do animal fat and oils both get trapped in our bodies the same way as subcutaneous fat?

Your body breaks most fats and oils down into its component lipids, triglyceride, and other component parts. This is much the same as how your body will break proteins down into amino acids and carbohydrates into glucose. Any storage will occur by converting it to normal body fat in the same way your body will store carbohydrates as body fat.

And does eating bacon grease of a poorly fed or sick animal affect us in anyway? Or this would all bypass the animal’s (removed) digestive tract and not necessarily be consumed by humans later? Thinking of heavy metals and pesticides, for example.

A few types of diseases, like mad cow disease, can be spread by eating cooked meat or fats that have previously been contaminated. Fat-soluble toxins will tend to accumulate in animal fats, and will be absorbed when the fat is consumed; this is mostly an issue with pesticides, mercury, and lead.

>The internet says seed oils are high in polyunsaturated fats and are can turn toxic at high temperatures. This is supposedly bad for you.

Fats heated past their smoke point (when they start to smoke) tend to become toxic in various ways. While cooking, you should take care to keep any fat you are using from smoking. As a note, this same applies to protein and carbohydrates as well. This toxicity is very low, and mostly results in slightly increased cancer risk.

>A lot of picked Italian products are preserved in oil.
>
>6) When I’m done with a commercial jar (canola oil for example), is it a safe idea to re-use the oil for cooking?

If the food itself was safe to eat, the oil is safe to cook with. That said, its probably a bad idea as you’ll get a lot of odd flavors from the food that was packaged or previously cooked.

You can also look into soap making, candle making, or processing the oil into diesel or lamp fuel.

>7) Does the presence of previously preserved food remnants start a bacteria growth process and this jar of used (but uncooked) oil should be discarded?

Storage of the oil is more difficult as it is likely contaminated with sugars and water and thus may support the growth of bacterial or fungus. The lack of oxygen means the most likely to grow is botulism, which is really hard to solve once the contamination starts – the toxins will survive almost all cooking.

That said, if it is refrigerated after initial opening and not stored past the original food’s storage limits, the risk is very minimal for adults. You should avoid giving any such food to infants for the same reason you should not give them honey – infants are at higher risk for oral intake of botulism.

As a note, you also should not make garlic-infused oil without cooking it for this same reason.

>Olive oil is touted as the healthiest oil to cook with…
>
>8) Is this a marketing gimmick? Chefs advise to avoided cooking with olive oil at high temperatures, but it seems like an oxymoron to me as you would think to use high temperature to kill bacteria on chicken etc.

As noted above, the toxin risk is once you hit the smoke point. Olive oil has a fairly low smoke point, limiting certain cooking methods.

Olive oil is made up of mostly monounsaturated fats (they have a bend in them), which is believed to be healthier than saturated fats (no bend) but not quite as healthy as polyunsaturated fats (multiple bends). Trans fats (one or more bends, but chemically altered to not have the drawbacks) are the least healthy according to current science, and there are very few natural sources of them, and those sources only contain them in very small quantities.

However, saturated fats are generally chemically more stable, and thus survive higher temperature better and are less likely to go rancid; polyunsaturated fats are generally the least stable. Saturated fats will also typically be solid at room temperature.

There are lots of differences chemically speaking the bonds are structured differently for the different oils and some are flexible, some are rigid some have many bonds and some have few. This changes the way they behave. Rigid bonded fats are solid at room temperature and generally are worse for you because anything solid can calcify in your body for example and its harder or impossible to remove and deal with solids.

Animals of poor health will be less nutritious and contain more toxins but as long as we are not eating too many toxins and enough nutrients our body does well with toxins. Not heavy metals our bodies do not do well with that but it would take heavy metals in the food already there they would not just manifest or it would be very very rare they do in livestock without them eating the heavy metals initially before we eat them.

Olive oil is liquid at room temp so we can ASSUME it is more healthy but there are tons and tons of situations in which olive oil could be less healthy. Depending on temperatures, other diet, exercise certain oils can be better or worse for you. You can look into the actual structure of fats in chemistry and the biology of how we break them down at websites like Kahns academy.

Bacteria is in the billions everywhere around you so for sure bacon has a bacterial profile that alters yours but that is to be expected with anything that enters your mouth.

Bacterial growth depends on the type of bacteria, and the nutrients and ambient temp/ light situations so it just depends on the situation but preservatives usually mean less bacteria but more toxins. Sometimes bacteria is good depending on what they are, all animals use bacteria to digest food.