Free fatty acid

[allane]

Someone wanted to sell me a lot of vegetable oil. Her claim is that it has a low free fatty acid. Is this good or bad ? Will this be good for soapmaking? Thanks for your usual help.

Allane

 

[ngian]

Low amount of free fatty acids means that the oil is fresh and / or in a good condition and moreover far away from rancidity.

So it is good to have an oil with a low acid value but the thing is how low it is. Is it food grade?

 

[allane]

Thanks nglan. You have given me a starting point. I am going to ask all these questions. I never thought to ask questions about free fatty acids of the oils I buy.

 

[DeeAnna]

If you're buying oil direct from the manufacturer, you should be able to get that information, but I doubt too many distributors are testing for free fatty acids (FFAs). Keep in mind that FFA levels will vary depending on the way the fat has been stored, so the % FFAs from the manufacturer isn't necessarily the same from the distributor. I want to also say a higher FFA content is not all bad -- it does not automatically mean the oil is rancid, nor does it mean the fat is inedible, although both are often assumed to be the case.

If low-acid fat is important to you, your best assurance of low acidity is to buy from a supplier who rotates stock so the oldest stock is sold first and who sells a lot of the particular oil you're buying. And care for your soaping fats properly when in your hands -- add an antioxidant, store in a dark cool area and/or refrigerate, and use promptly.

Fats high in FFAs will trace faster in proportion to the amount of FFAs in the fat. More FFA = faster trace. You can use fatty acids alone or in part to make soap -- some manufacturers do exactly that. If you make shave soap with added stearic acid, you have soaped with FFAs.

 

[Susie]

You also need to know what kind of vegetable oil. I don't soap with soy oil. My only rancid bars had soy oil in it. Make sure the oil is something you actually want to use.

 

[topofmurrayhill]

Get the claimed number if possible. There's low and there's low. The number might not sound high but 2% FFA in olive oil classes it as unfit for human consumption. Just a fraction of a percent is normal for fresh refined liquid oil. Just EV or virgin OO are liable to be higher. It's a strange way for someone to market oil to an end user.

 

[ngian]

I want to also say a higher FFA content is not all bad -- it does not automatically mean the oil is rancid, nor does it mean the fat is inedible, although both are often assumed to be the case.

I think that higher FFA in oils means that the oil is on its way to rancidity as FFA will later brake up into smaller particles which give the specific rancid smell. FFA that have already detached from the glycerol molecule because of heat, time, humidity and oxygen (and not from NaOH) it means that they are somehow already weak and when they are saponified they might show DOS more easily in a soap bar compared with an oil with lower FFA content.

I guess that this is not the same with stearic acid which is a more stable saturated acid and can be found alone in the market.