Did my soaps went rancid?

[Lyma]

Hi to everyone,
I'm making olive oil soaps (4% superfatting)
I'm having discoloration problems with some of my soaps and i don't know if it's rancid issue or just an aesthetic problem from curing process.

The discoloration occurs always at the bottom of the soap as they cure. The soaps cure at perforated metal sheets for two months and over.

The problem usually appears after 2 months curing and not in all soaps of the same batch.

I attached a related picture.
In the first soap the problem is obvious, in the other four it's less obvious.

From my experience, yellow spots which are rancid sign, appear when i leave a soap in warm and bright space for months and can appear all over the soap and not only at the bottom.

The problem in the picture doesn't seem like yellow spots, occurs only at the bottom although soap cures in dark and dry place.

Is it from the curing process and the air that circulates from the perforated sheets or is it rancid?

Need help

 

[navigator9]

The one on the left sure looks like DOS to me. Does it have a rancid smell? Have you always cured your soaps on metal sheets? Depending on the metal, I would think that fresh soap, when the lye is still active, could be reacting with that metal. Try curing your soaps on something other than metal and see if this solves the problem.

 

[pamielynn]

Yeah, that looks like a metal reaction to me, as well.

 

[shunt2011]

It's most certainly a reaction to the metal. The one on the left looks like DOS to me as well. I would not cure soap on metal. I use metal shelving but I line it with perforated heavy plastic that breaths and allows air to circulate.

 

[Susie]

Exactly my thoughts. If you can't find something other than metal, then try using some parchment or freezer paper below the soap. And turn the soap about every 2 weeks.

 

[Lyma]

To be honest i didn't know that the contact with the metal could cause DOS.
The metal i use is stainless steel and i've read that it's safe in contact with the soap.

If you are right and the problem is the contact with the metal, then why it appears after two months and not after one week where there is more active lye?
And also why it appears in some batches of the same recipe and not in every batch, as the curing process is exactly the same.

Anyway, i've already lined the metal sheets with freezer paper and waiting for the results for the new batches.

Thank you all. Hope to solve the problem.

 

[navigator9]

I think it's worth a try to cure your soaps on something else and see if the problem disappears. If it does, you know it was the metal sheets. If not, then you can start over again, trying to figure out what's causing the problem. But I would start with changing where you cure them. Good luck to you!

 

[shunt2011]

It may also be that your oil isn't fresh and perhaps high humidity and other temperature factors. Hard to say.

 

[eucalypta]

Looks like DOS to me.
DOS occurs after the saponification process.
Humidity may be of influence; there is no circulation at the bottom of the soaps, where they come into contact with the metal.
Put hem on a paper towel.

Pizzaboxes are great for storage; turning the soaps around every now and then helps too.

Usually OO is not prone to DOS; Might the oil be adulterated?' ope not!

 

[Lyma]

The metal sheets are perforated so that there is air circulation at the bottom.

The OO is certainly not adulterated, it's our own crop from this year. Maybe it's the avocado oil (first soap on the left of the photo) or the coconut oil (the other three in the photo) which i use in very low percentage (5-10%).

If it's DOS, then this could happen because of the adulteration of some of the oils or because of the contact with the metal?

And if it's DOS, quite obvious on the first from the left, why on the other three soaps the spots are not yellow but something like green-blue, or something like discoloration?

 

[eucalypta]

The metal sheets are perforated so that there is air circulation at the bottom.

Right; I see no pattern (like perforation) on the soaps.
Did you clean the metal sheets with something particular?
(I don't know; wild guess, just ruling everything out)

The OO is certainly not adulterated, it's our own crop from this year. Maybe it's the avocado oil (first soap on the left of the photo) or the coconut oil (the other three in the photo) which i use in very low percentage (5-10%).

Perfect! How cool to have your own oil!.
The shelf life of Avocado is approx 1 year; CO longer.

If it's DOS, then this could happen because of the adulteration of some of the oils or because of the contact with the metal?

I'm beginning to doubt the DOS.
The light here is different now; I clearly see a white edge arount the yellow spots. That is not typical for DOS.

And if it's DOS, quite obvious on the first from the left, why on the other three soaps the spots are not yellow but something like green-blue, or something like discoloration?

The spots on the other soaps are harder to see; but they don't resemble DOS - definitely not orange; so I suspect that there's something else going on.
- Do you smell anything near the spots?

To rule everything out: (let's go for the soap on the left)
- What utensils do you use? Stickblender, spatulas (wood/silicone)?
- mould/lining
- used fragrance oil/EO
- other additives?
- What about the NaOH? Is it pure (99%) or does it contain aluminium for example?
- could you upload a picture of a metal sheet?
- as asked above: how do you clean the sheets and with what?
- is it possible that anyone could have spoilt anything on the sheets?
- stainless steel comes in qualities; sometimes it is just a coating. I don't think it is the problem because the spots are random, but anyways.
- during the two months of curing, did you rotate the soap?

Perhaps you could do a test: cut one bar in half; put one piece (cut side down) on the metal sheet, and the other half the same way on a paper towel in a box/rack/shelf. Wait and see if something wil happen.

Sometimes you have to dig deep to find the problem.

 

[Jaccart789]

I think its the metal. Lye should not have contact with aluminum.

 

[Dorymae]

It could be different problems. The blue-green could be caused by the metal, the orange could be DOS. I think you made the right choice in covering the metal, now if you only get orange spots you'll know the blue/green might have been because of the metal and the orange is something else, or vice-verse of course.

If there is no off odor to give away DOS, then you are left with the process of elimination.

 

[eucalypta]

I think its the metal. Lye should not have contact with aluminum.

That's right; only stainless steel is not aluminium ....

 

[pamielynn]

DOS doesn't always come out as "orange" - depending on what's in your recipe, rancidity can show up in multiple ways. I also use a stainless-coated rack, but I cover the shelves with newspaper paper - you know, the unprinted kind. It's really inexpensive to buy in bulk. And when the weather is hot and humid (basically all summer, here) I rotate them.

If the room they are curing in is too hot, they will go "bad" faster, as well. A fan helps.

 

[Lyma]

Wow, you are all really helpful!

If only the first soap on the left had this problem then the explanation would be simple: It's the avocado oil which is not fresh (at least 2 years).

But things are getting confused when i observe similar spots in the other soaps that don't contain AO, just fresh OO and CO.
Yes i know, the spots are not so obvious in the other three soaps, but the look similar to me. Same figure and always at the bottom. Just different intensity and color.

In the first soap i slightly smell something like rancid, in the other three no. But it makes sense, because the first on the left is without essential oil, the other three contain EO.

I attach a sample of the stainless steel sheets i use for curing.

- I leave the soaps cure for at least 2 months (some stay for 3-4 months if i don't have any orders).
- They cure in a closed room without light, with a dehumidifier. The room temperature now in summer is 26-27 C.
- I don't rotate them because the sheets are perforated.
- I clean the sheets just with water.

Also 2 clues that might help:
1.Α soap from the same batch with the one on the left that was packaged in recycled paper immediately after 2 months curing, didn't appear any problem.
2. When i cured my soaps in wooden shelves lined with paper, never had similar problems. Just reasonable DOS if i left them for several months in inappropriate conditions. When i changed the wooden shelves with the perforated inox sheets, so that there is air circulation at the bottom to fasten cure period, these problems appeared.

I hope the problem is the sheet, because the frozen paper will solve everything.
But if it's oxidation then things are getting confused. And if it's oxidation, DOS etc. why the spots appear only in the bottom and not in any other surface?

 

[navigator9]

By changing one thing at a time, (like lining the shelves with paper), you should be able to figure out which one of the variables is the problem. It may take a while, but once you figure it out, it will be worth the effort. Good luck to you, your soaps (other than the spots) look lovely. :grin:

 

[leeleetrue]

I was pondering the influence of metal on DOS the other night...i have a coated metal shelf that has a few nicks in the coating, where the metal has rusted. it makes sense (at least in my head) that oxidizing metal could very well lead to oxidation in soap - DOS. I can't speak to the blue-green spots, but i will say that in some soap of mine that eventually got DOS, my first clue to something being wrong were white spots, which eventually turned orange. in my woeful history with DOS, i didn't necessarily see spots in more than one or two places on any given bar; it makes me wonder if your spots are only showing up on the bottom if it is indeed oxidation from contact with the metal. i like others' suggestion of lining the shelves with paper. i think i'll try it here in my studio, too, and see if that helps. best of luck, i know what a pain it is to discover these issues with soap you've made.