I keep reading it;
'the inherent stability of the monounsaturated fatty acids present in olive oil' - marks daily apple.
Ive read it on here to a few times in regards with saturated fats, oh coconut oil is very stable that's why I use it.
what is a stable fat, what are the benefits of a stable fat, and what are unstable fats and why are they dangerous? - im just assuming the dangerous bit.
asked byWhirl (195)
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on June 20, 2012
at 01:24 PM
The more saturated a fat is, the more "stable" it is -- that is, the less likely it is to go rancid or become toxic in some way.
What makes oils and fats go rancid or oxidize? Heat, light, and air.
The more saturated a fat is, the better suited it is for cooking -- beef tallow, lard, coconut oil, butter, palm oil. The oils that are mostly monounsaturated are also okay for cooking, but some people prefer to use them "raw," like drizzled on salads or even as a kind of garnish. (Especially with good quality extra virgin olive oil, where you'd want to preserve the flavor.) Mostly monounsaturates include olive oil, macadamia oil, almond oil, and avocado oil. (Canola also, but most of us stay away from that for other reasons.) Most people don't use the latter 3 for cooking, since their flavors would get lost. You'll see a lot of debate about cooking with olive oil. It is pretty "stable," since it's over 70% monounsaturated and about 14% saturated. Some people use it only for "light" cooking and not high heat.
The polyunsaturated oils are the most susceptible to oxidation and woudl be considered the most chemically "unstable." (Corn oil, soybean, safflower, sunflower, cottonseed.)
If an oil gets oxidized or turns rancid, not only does it smell and taste bad, but it can be pretty damaging to your body on a cellular level. (If you want the nitty gritty details on what it does to the cell membrane, I can go there, but I'm guessing at the moment you're just looking for the basics.)
The interesting thing is, most bottled oils you find in stores are rancid and oxidized before you even bring them home. The process by which they're refined and extracted from their natural state (whatever seed, nut, grain, or vegetable they come from) usually exposes them to air, light, and very high heat. (Not to mention various solvents that are used to chemically extract even more oil.) And they're in clear plastic bottles on the shelf, where they're under lights 24/7. And then we bring them home and cook with them, exposing them to heat yet again. It's a jungle out there! ;-)
Anyway, this is why sometimes it's better to stick with "unrefined," "cold-pressed," etc. There's a lot of confusion about fats and oils, but hopefully this helps a little.
on June 20, 2012
at 01:23 PM
Fat can go bad through a process called rancidification. When a fat is relatively resistant to this process, we say that it is stable. In fact, there's an empirical measurement called Oil Stability Index (OSI) for this. Some fats, especially animal fats, are much less prone to going bad than others. Stable fats are thus beneficial because they can be stored more easily and for longer.
As the fat goes bad, it breaks down into peroxides and eventually into organic acids that ruin the flavor. If the rancidification occurs due to microbes, it can create toxic byproducts.
on June 20, 2012
at 01:22 PM
Generally, this refers to how susceptible the fat is to oxidation. Saturate fats are less susceptible to oxidation, whereas polyunsaturated fats are more susceptible. MDA has a brief explanation here: http://www.marksdailyapple.com/rancid-fat-store-bought-mayo-and-ric-bran-oil/#axzz1yL4XSDjg
Oxidized fat and cholesterol can lead to atherosclerosis. Chris Masterjohn writes, "In short, oxidized LDL contributes to the entire atherosclerotic process from start to finish." http://www.cholesterol-and-health.com/Does-Cholesterol-Cause-Heart-Disease-Myth.html#oxidized
on August 28, 2012
at 05:34 PM
What would you say in response to this regarding lard vs. vegetable oil's stability?
"The oxidative stability of lard is no better than vegetable oils with high levels of polyunsaturates, even though lard is very low in polyunsaturated fatty acids. Lard does not have any natural antioxidants like vegetable oils. Most vegetable oils don’t go rancid till the peroxide values are in the 70 to 100 meq/kg range. Lard becomes rancid at a peroxide value of only about 20 meq/kg."
This was from a chip company rep. They use preservatives in their lard-fried chips and I wrote saying the preservatives weren't necessary because of lard' stability. This was their response, which is over my head. Thoughts?