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JBot

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So I found an inexpensive olive oil that I really like (from Costco, but not the Kirkland brand), and one of my new favorite recipes contains 45% olive oil. That's more than I've ever used before. I've heard that olive oils are often adulterated, and using them in high amounts can lead to DOS.

I'll be watching the bars to see if any develops, and I'm wondering: how much time (assuming no signs of DOS) should I give them before I can be reasonably confident that the olive oil is probably ok? In other words, if you've had a soap get DOS, approximately how old was it when it showed up?
 

Obsidian

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Mine usually show up within 2-3 month though I've had some take over a year to develop. The fastest was a castile made from a costco brand of light OO, not kirkland. I can't remember the name but it got DOS within a month.
 

rbecca74

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hmm... I don't have an answer for your question, however I would like to know the answer as well. I buy my Olive oil from Costco. not EVOO, but plain olive oil. So would be great to know.
 

Dorymae

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So I found an inexpensive olive oil that I really like (from Costco, but not the Kirkland brand), and one of my new favorite recipes contains 45% olive oil. That's more than I've ever used before. I've heard that olive oils are often adulterated, and using them in high amounts can lead to DOS.

I'll be watching the bars to see if any develops, and I'm wondering: how much time (assuming no signs of DOS) should I give them before I can be reasonably confident that the olive oil is probably ok? In other words, if you've had a soap get DOS, approximately how old was it when it showed up?

I was always under the impression that DOS can rear its ugly head anytime after a month. When are you safe? I don't think you are - really it would be when you believe the soap will be used or sold. So pick an time on the outside and see if your soap makes it.
 

JBot

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Mine usually show up within 2-3 month though I've had some take over a year to develop. The fastest was a castile made from a costco brand of light OO, not kirkland. I can't remember the name but it got DOS within a month.
Hm, that makes me nervous. . .I've been using the "Montolivo Extra Light" olive oil. Does that sound like what you were using?

hmm... I don't have an answer for your question, however I would like to know the answer as well. I buy my Olive oil from Costco. not EVOO, but plain olive oil. So would be great to know.
Have you had any DOS?

I've been using the Montolivo since the end of September without any problems, but at about 30%. Using 45% is very recent, so I think I might be watching it carefully for a while.
 

Obsidian

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Yes, it was the Montolivo Extra Light I used. Its possible the bottle I had was old to begin with but I've not used that brand since and my castile doesn't get DOS anymore.
I'd play it safe and get the kirkland brand, it might cost a little more but its tested pure.
 

JBot

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Yikes. Anybody have suggestions for how I can "stress test" it? Heat, moisture?
 

DeeAnna

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How do you expect to know if your soap gets DOS that it is directly caused by the olive oil, whether adulterated or pure? Maybe its metal contamination in your water or other additives. Maybe it's coming from the other oils in your recipe (assuming you're not making castile). Maybe it's your EO or FO or colorant. Maybe it's air pollution or how you store the soap while it cures.

What I'm trying to say is that there is nothing wrong with the ideas of using oils that are as fresh as possible and minimizing the linoleic and linolenic acid content to reduce the chance of rancidity. But there are many other things that trigger DOS/rancidity. It is hard to know the actual causes.
 

JBot

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How do you expect to know if your soap gets DOS that it is directly caused by the olive oil, whether adulterated or pure? Maybe its metal contamination in your water or other additives. Maybe it's coming from the other oils in your recipe (assuming you're not making castile). Maybe it's your EO or FO or colorant. Maybe it's air pollution or how you store the soap while it cures.

What I'm trying to say is that there is nothing wrong with the ideas of using oils that are as fresh as possible and minimizing the linoleic and linolenic acid content to reduce the chance of rancidity. But there are many other things that trigger DOS/rancidity. It is hard to know the actual causes.
All good points. I guess I was thinking about it from the other direction: if the soaps made with that particular olive oil could make it past a certain age or hold up under certain conditions WITHOUT developing DOS, then could I be reasonably confident that at least the olive oil specifically is not going to cause or contribute to DOS in the future?
 

DeeAnna

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I don't think you can count on any one given brand of olive oil as being "DOS proof". If for no other reason than normal variations in manufacturing and storage conditions (temperature, exposure to light, water or metallic contamination, etc) have an impact on the properties of the oil as it comes from the producer, while it sits on the store shelf, or when you have it in your pantry.

Some oils are more prone to DOS, yes, that's true, but in this case, we're not comparing brands of a given type of oil, we're talking about comparing entirely different oils. The ones that are more prone to DOS are mostly the polyunsaturated fats (corn, peanut, soy, grapeseed, etc.). When you start talking about coconut, palm, palm kernel, olive, avocado, lard, tallow, etc. -- they can become rancid too, but the likelihood drops because these are mono-unsaturated or saturated fats with fewer or no double bonds to cause trouble.

For me, avoiding rancidity means doing a bunch of things -- use quality ingredients as much as I can manage, work clean, store my ingredients properly, minimize metallic contamination, keep my hands clean when working with the soap, keep the soap clean and dust free in storage, avoid exposure to light, etc. And I'm looking into the use of chelators (EDTA, citrate) and antioxidants (rosemary oleoresin, ROE) in my soap as further insurance against DOS.
 

JBot

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For me, avoiding rancidity means doing a bunch of things -- use quality ingredients as much as I can manage, work clean, store my ingredients properly, minimize metallic contamination, keep my hands clean when working with the soap, keep the soap clean and dust free in storage, avoid exposure to light, etc. And I'm looking into the use of chelators (EDTA, citrate) and antioxidants (rosemary oleoresin, ROE) in my soap as further insurance against DOS.
I try to do all of those things as well! It's tricky to keep them dust-free while they're on the curing rack, but I'm working on making a breathable tent for that. They don't get much direct exposure to light -- maybe 30 minutes per day on the top rack at certain times of the year, when the sun comes through one particular window at a specific angle -- but it couldn't hurt to have the tent shading them from that as well.

What portion of the curing time do you keep yours sitting out? I usually have mine on the rack for 4-6 weeks before I wrap them in paper. Initially I was putting the wrapped soaps in shoeboxes, but that's gotten cumbersome, so lately I've been stacking them in paper lunch sacks. They aren't getting as much air circulation as they do on the rack, but I figure it might be a little bit better than the shoeboxes. I often leave the paper bags standing open at the top.

I've been using sodium citrate almost since the beginning. I understand that Dunn's tests showed it didn't do much on its own to prevent DOS, but I thought it might help the soap lather better for people with hard water. I've recently been experimenting with using BHT as well. It doesn't seem to be a very popular additive, but the stabilizing properties of combined sodium citrate and BHT are highly appealing. Once I give a bar away, I have no control over how it's handled or stored, and I want to maximize the chances that people will have good experiences with the soap even if they store it in poor conditions.

So far I've done 3 batches and 6 small testers with BHT. Of those, one batch and two testers have turned bright yellow; the jury's still out the third batch. I made it just yesterday, so there's a chance it will also turn neon yellow in the next few weeks. Right now the theory is that it has something to do with fragrance oil, since a single batch split 4 ways and scented with 4 different FOs has yielded different results -- 3 portions turned yellow, 1 portion did not.

I'm planning on starting a new thread about the BHT discoloration issue, but since hardly anybody seems to be using it, I don't know if I'll get much of a response. My search of past threads didn't turn up very much information, and neither did a google search. What little I've been able to find on the topic is highly technical material that's way over my head.

If you have any insights, I'd really appreciate hearing them!
 
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