Fatty acid profile and SAP numbers

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Alibru09

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Hello everyone,

I have been making soap for some time now but have only recently taken an interest in formulating my own recipes. After reading a very informative post by DeeAnna regarding interpretation of soap calc numbers, I thought I would take a closer look at the fatty acid profiles of oils I am currently using or plan to use.

However in doing so I have found somewhat inconsistent results.

Taking one oil as an example:

Supplier1: linoliec acid result 12%; oil pure virgin; no Sap number provided
Supplier 2: linoliec acid result 45%; oil pure , sap no 0.136

All other acids are within +- 10%

My questions are:

1. Would the variance in linoliec acid be simply natural batch variances?
2. Would the variance be sufficient to change the sap number?

If the answer to Q2 is yes, then this has some interesting implications, in particular should we be requesting batch specific sap nos from our suppliers?

Thanks in advance
Alibru
 
Soapcalc lists the sap value for virgin oil at .135 and the sap value for olive pomace at .134, so it may vary slightly. Soapcalc also lists virgin olive and pomace with a linoleic value at 12%. I would wonder about that 45% listing.
 
I'm not sure what oil you are referring to in your original post, but, yeah, fats can vary a lot in their fatty acid makeup. Soapcalc lists lard at an average of 46% oleic acid, but I have fatty acid analyses of lard that average 33% oleic.

Also, be sure to compare apples and apples. For example, high oleic versions of safflower and sunflower are much lower in linoleic than the non-HO versions. Soapcalc shows HO safflower will average 15% linoleic and 75% oleic, but the non-HO safflower percentages are reversed.

Would the variance change the sap value a lot? Might. Depends on the fatty acids. Lauric and myristic have a high sap value so variability in these two fatty acids vs. the other fatty acids will skew the results more than variations within the oleic, linoleic, and linolenic acids. Many of the liquid vegetable oils don't vary that much. For example, HO safflower and sunflower vary from their non-HO brethren by 0.001 g NaOH/g fat. That's well within the normal error for soap making.

It can never hurt to verify with the supplier, however.
 
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