randicity and gelling

[catikit]

Hi there,
I make a very mild baby soap bar which when made in a large loaf mold and allowed to gel, lasts for ages. However, when i make this in a mold with individual cavities, it doesnt gel (presumably because there's insufficient volume to create and maintain the heat...) and i find these bars sometimes go rancid very very quickly (within weeks). Why is this?

 

[judymoody]

What oils do you use in your soap? And what % superfat?

 

[catikit]

I use a 5% superfat. All my oils are pretty stable - coconut, palm, olive, sweet almond, avocado, shea butter.

 

[sudbubblez]

What is the linoleic and linolenic profile on this recipe?

The easiest way to say it is... with the gelled soap, the delicate fatty acids have been destroyed by thermal deterioration. Oxidation from the air is a chain reaction caused by free radicals which react with other molecules to produce more free radicals; you will see this as DOS that grows and spreads, can even spread to other soaps that the spoiling bar is touching. It also has something to do with electrons, which is why some metals can act as a catalyst to speed the process. A fatty acid that has already been destroyed and changed by heat can't oxidize from the air. The fatty acids in both soaps have gone bad or are going bad, just in different ways.

You may want to add an anti oxidant single mold CP soaps or change the recipe to include an oil high in antioxidants.

Most stable (1 year): Avocado, castor, coconut, jojoba, olive, palm, and wheat germ.
Stable (6 to 12 months): Almond, canola, corn, cottonseed, peanut, and sesame.
Less stable (3 to 6 months): Borage, evening primrose, flaxseed, grapeseed, kukui, rose hip, soybean, and sunflower.
Unstable (0 to 3 months): Safflower (linoleic variety) and walnut.


If your linoleic and linolenic profile is within range, the next thing to look at would be environmental factors.

 

[HutCar92]

I use all of those oils, minus Almond, and I also use Avocado. I have many bars that are over a year old and in between and I have never had DOS. I have both gelled and ungelled bars and I superfat at 7%. My uneducated guess (haha) leans towards the almond oil, or depending on where you live maybe the humidity? Also, I only ever use distilled water and coconut milk in my soaps. Maybe if your using tap water or rainwater that could also have an impact, I know there are plenty of soapers that do, and I wonder if they ever noticed anything....

 

[Aquarius]

Since you guys are discussing this I have a question.

I have made 2 batches last week with olive, palm, coconut and castor and use rosemary extract as an antioxidant at 0.1% of total oils weight.

I took the soap out of the mold today (after 2 days) and after removing the lining paper I spotted little darker orange dots on the inside of the lining paper, I deducted that it's the rosemary antioxidant...but why is this happening, I used ROE befor and never saw this ??

Does it have something to do with the base oils or the essential oils (I used Peppermint and Eucalyptus)

 

[catikit]

Hi all,
I only use distilled water. My workshop is fairly cold (no heating in there, wooden floors, old stone walls) but i cure the bars at home where its a more temperate environment. Some bars (made in single cell molds) appear to go rancid unbelievably quickly whilst others from the same batch seem to last fine for years. Loaf mold bars, which i cut up, never seem to spoil in this way. I just cant seem to fathom it....

Oh and re: the rosemary soap - i made a rosemary and orange oil soap (in a loaf mold) and that had small orange spots in it straight out of mold too.... I had wondered if it was the orange oil...

 

[Aquarius]

I think it's the rosemary extract leaking out but not really sure, first time that happend and i've been using the ROE for about 2 months now...

 

[sudbubblez]

Theres another possibility. It has been known for decades that mold causes oils to go rancid. Hot processing may just be doing a better job at sterilizing the oils. This would explain why DOS has been known to spread from one bar to another if the bars are touching. Oxidation is a chain reaction too. The only way to tell the difference is to test for the chemical compounds that result from mold. Mold takes many forms and isn't always a visible growth on the surface.

Heres a paper about mold and coconut oil if anyone is interested

http://www.ncbi.nlm.nih.gov/pmc/article ... 92/?page=1

 

[catikit]

Very interested - thank you very much!