Calculating saponification value from a product's fatty acid profile

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Rune

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Can anyone help me with calculating saponification value based on fatty acids? Is it possible at all?

We have a product in grocery stores here called Flott Matfett. That is a mixed product containing (in falling order): Shea fat, coconut oil, rapeseed oil.

It is used for deep frying baked goods like "smultringer", which is a norwegian type of donut. So this plant based product is meant as an alternative to lard.

I mailed the company and asked for the exact percentages of different oils. They could not give me that. But they could give me the what fatty acids it contain and how much.

I have tried to find it out by using a lye calculator, but it did not match whatever I did. I guess this shea fat is not the same as shea butter. Well, I'm quite sure about that. And the rapeseed oil is most likely high-oleic and maybe hardened in some way. It is a frying fat.

I want to use it for soaping, but need to find a sap. value, or at least an approximate one. I want to use it because it is available. And the only locally available shea fat. Plus I get coconut for bubbles as well. And it does not contain very much rapeseed.

Lauric C12 13 %
Myristic C14 5 %
Palmitic C16 8 %
Stearic C18 29 %
Oleic C18:1 33 %
Linoleic C18:2 5 %
Linolenic C18:3 0,5 %

Saturated - 58%
Mono-unsaturated - 33%
Poly-unsaturated - 5%

Yes, it's not shea butter it contains, most likely. But something cheaper they call shea fat. But who cares since it will be saponified anyway. So I don't think it has to be the most exclusive, especially not for cold process where you can't deside what and what not to add as a superfat.

Because of the limited availance here for everything, it would be great to be able to use it instead of having to only rely on orders from abroad. I want to try this fat combined with some olive oil, it may make a nice and gentle soap, I hope :)
 
The issue comes with any unsaponifiable parts of the mix.

How are your excel skills, or even with a pen and paper? You look at the fatty acid profiles of the oils in the mix and work out which combination or combinations of them give you the same profile as the mix. Coupled with the sat:unsat ratio, I think that it is possible to work out the mix and calculate your recipe accordingly
 
Yes, you can calculate a theoretical saponification value. Find or calculate the molecular weight of each fatty acid. Find the average molecular weight of the fatty acids based on the information given to you by the supplier. Calculate the weight proportion of glycerin to the average fatty acid using the stoichometric relationship of 1 mole glycerin to every 3 moles of fatty acid. Include an estimate of the unsaponifiable chemicals. Based on the stoichiometric ratio of alkali to fatty acids (not fats -- I mean fatty acids) of 1 mole alkali to 1 mole FAs, calculate the the moles of alkali required in milligrams of alkali (KOH or NaOH) to grams of fatty acid. Add in the grams of glycerin and unsaponifiables to correct the sap number to mg alkali to grams of fat.

Lots of tedious, careful pencil pushing or spreadsheet work, but it's basic chemistry 101.

But you'd be far better off to test the sap value of the actual product -- you will have a much better chance of getting a reliable, accurate number. See Kevin Dunn's book Scientific Soapmaking for the method.

"...I guess this shea fat is not the same as shea butter. Well, I'm quite sure about that...."

Why are you "quite sure" about that?
 
Thank you both for great answers! :)

Sure and sure about shea fat being butter or not, well I should not have wrote that since I know far too little about shea. But since it is an industrial product, I suspect it is some lower grade things. Not that shea butter can't come in lower grades. But they wrote shea fat on the label, not shea butter. It is written in norwegian, and we have a word for shea butter, instead they wrote shea fat. It can be that they ment shea butter, though.

I googled just now, and the producer writes:

"What is shea fat?

Shea fat or shea oil is an oil that is extracted from the nuts of the shea tree.
It is a tree that grows wild in West-Africa. Shea fat is uses in Flott Matfett, among others."

So it is shea oil. I think I have seen that in a lye calculator as well. And Sheabutter.com says it is a byproduct from shea butter production. And that makes sense, since Flott Matfett is an industrial type of margarine for deep frying. And they often use cheap byproducts in those products, at least in Norway.

I think I will try your two methods first, DeeAnna, and if I don't manage to do that, I will try The Efficious Gentleman's method. Which was sort of what I tried first, before giving up. But what I did find with that method, is that rapeseed is in small amounts. I was closest to match the fatty acid profile when rapeseed was around 5% (I don't remember exactly).

To test the sap value of the actual product as in Scientific Soapmaking, yes, a good idea! Thank you so much! :) I have never (almost) heard of it before, but I will figure it out. Just have to buy the book first. I will find it in E-book, so I can start using that method right away.

And the first method, that should not be too difficult either, since I actually mastered advanced mathematics, to my shock! (I had zero skills to begin with, but had to learn it at college in only 1 year. It went just fine). So I'm quite sure I can figure out the first method as well, if the Kevin Dunn-method don't work or I mess it up completely.

So thank you :)
 
I realize that I made a big mistake- we don't need to consider unsaponifiables when looking at lye......because they don't saponify! My bad.

But the ratios can work. Just be sure to check for multiple combinations rather than just assuming that the first one is the correct one.
 
No, they don't saponify, but they do reduce the sap value of the actual fat by their presence.
 
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