Maxing out Rapeseed oil %

[saddigilmore]

Rather it implies low in poly-unsaturated fatty acids (linoleic and worse), which impart longevity and heat stability (DOS danger in soap

This was counterintuitive to me- I would have thought things that would increase the shelf life of oil, would, in turn, increase the shelf life of soap made from it. If an oil goes longer without going rancid, wouldn't the soap, take longer to develop DOS?

The typical cheap Rapsöl you get in German supermarkets has some 25…30% PUFA
In oils with varying PUFA content, the degree of unsaturation has next to no impact on the saponification values:
The content of oleic acid by itself is the only uninteresting parameter of an oil/fatty acid profile.

This does seem to be the case, my rapeseed oil has a 25% PUFA....
I am not nearly well versed enough to start entering custom values into the lye calculator... I only feel comfortable choosing between unrefined rapeseed oil (which I originally would have chosen, but it seems that german rapeseed oil is closer in SAP value to the canola entry in soapcalc), High Oleic acid Canola, or just plain Canola oil. I don't know which one matches the supermarket rapsoil best.

Which entry would you choose, given the oil I'm trying to work with? it's 60% Monounsaturated , and 25% Polyunsaturated (mid-oleic?)

Thanks

 

[ResolvableOwl]

This was counterintuitive to me- I would have thought things that would increase the shelf life of oil, would, in turn, increase the shelf life of soap made from it. If an oil goes longer without going rancid, wouldn't the soap, take longer to develop DOS?

HO = stable is the case. It might be that you're just overthinking it, or I suck at explainig

Oleic acid = mono-unsaturated = long shelf life of oil and soap
Linoleic acid = poly-unsaturated = short shelf life of oil and soap, DOS hazard
Erucic acid = mono-unsaturated = long shelf life of oil and soap (added for completeness, very low content in edible oils)

HO means a lot of “space” taken by oleic acid that can't be linoleic, so low DOS risk.
Similarly, inedible rapeseed oil is high in erucic acid, hence again, less space for PUFAs, and low DOS risk.

Regular canola (the cheap plastic-bottle Rapsöl) is at 25…30% PUFA, intermediate DOS risk. Soapmakingfriend & friends list “Canola oil” with 61% oleic acid, 30% PUFA, at SAP 0.133. Hence this is a reasonable choice which has worked well for me so far (due to some first-world problems, I'm currently in a hiatus of canola/rapeseed/Rapsöl for soap).

With rapeseed and its descendants, there is no such thing like a really “high-linoleic” variant (unlike sunflower). I've never seen PUFA well above 30% in stores or in soapcalcs.

I also have never found out how to obtain HO canola oil (PUFA < 20%). I know of its existence only from soapmaking tables/calculators.


The distinction of high-oleic and high-PUFA variants is crucial for safflower and sunflower oils, but by far not as urgent for rapeseed/canola.

 

[saddigilmore]

It might be that you're just overthinking it, or I suck at explainig

It was neither, I'm just a straight noob lol

Soapmakingfriend & friends list “Canola oil” with 61% oleic acid, 30% PUFA, at SAP 0.133. Hence this is a reasonable choice which has worked well for me so far

This is what I'm going to go with! It makes sense, I hearing you confirm it makes me feel a lot more confident! hahah. thank you ))

I know of its existence only from soapmaking tables/calculators.

I had so much from messing around on soapmakingfriend/soapcalc before I bought my first bottle of lye

 

[paradisi]

I initially didn't know you're based in Europe/Germany. Canola is (or, initially was) a brand name for Canadian GMO rapeseed oil, that (AFAIK) never was sold in Europe. The name diffused to edible (low erucic) rapeseed oil in general. That means that both statements are right: “Canola is a brand name for edible GMO rapeseed from Canada” and “In Europe, you can buy non-GMO, low-erucic food-grade rapeseed oil cheap in every supermarket”.
It's a mess. But is it important? Yes! Inedible “rapeseed oil” (high erucic) and edible “canola oil” (low erucic, both GMO and non-GMO/conventional breedings) have different saponification values. Online soap calculators, invented across the pond, exist in a different market, and call the same things differently. Here is a German SAP table that states “Rapsöl (Brassica oleifera)” NaSAP=0.1354 much closer to “canola” 0.133 than “rapeseed” 0.125.
Using a too low SAP would have meant excess superfat – which you arguably want to avoid.

North American farmer here; Canola doesn't denote GMO, as it's varieties bred in Canada by normal means in the 1970's, before GMO were possible, to make a northern grown oil crop for humans by lowering the erucic acid content. And it's still very much available. .
Non-GMO Canola Oil | Expeller Pressed Canola Oil - 35 lb.
https://www.webstaurantstore.com/non-gmo-expeller-pressed-canola-oil-35-lb/101NGMOCANOL.html

 

[saddigilmore]

here's what my rapeseed experiments look like after one month of curing... most have DOS throughout... some actually turned Fully orange? (3+4 row from bottom). Some concentrated near the stamp only (2nd to last and last row)

DOS didn't seem to develop at all on the ones that I added coffee grounds to... Was thsi because I didn't stamp it? or because Coffee grounds are an antioxidant/chelator?

Gonna test these out on my hands this week, and have a final tally. I can safely ignore the DOS, and do my tests blindfolded, and rely on the results, right? DOS is ONLY cosmetic?

thank you all!

 

[KimW]

hmmmmm...I wouldn't call DOS cosmetic...or were you being sarcastic, perhaps? Sorry, hard to tell in written comm.

DOS is soapy slang for rancidity, so I wouldn't say it was "just cosmetic". Just a thought! But, yes, I see no reason not to do some tests, but if it were me I'd wash my hands with good soap afterwards and then either salt out the bars with DOS or *gasp* throw them away.

 

[saddigilmore]

I'm gonna toss em for sure, I just wanted to fine tune my recipe... a soap w DOS, I just want to make sure that after adding chelators/antioxidants, it will behave like the DOSSY soap did...