What’s happening here as I melt the hard fats?

[Mobjack Bay]

I know I’ve been asking entirely too many questions, but please bear with me. I’m trying to learn how to use something other than lard or predominantly soft oil recipes.

I made a recipe today using 30% PO, 10% shea, 20% CO and the rest OO with a little RBO and castor. I wanted to really pay attention to what was happening as the PO, CO and shea were melting, so I heated them slowly in a stainless steel bowl over a water bath. Unfortunately, I did not track the time, so I could be off on my estimates. First off, everything was liquid by the time the mixture reached 110 F, but it was far from clear (didn’t get a photo). It was still pretty cloudy at that temp after another 5-10 minutes so I nudged up the heat. About 15 minutes later, the oils were at 136F and looked clear at first glance, but when I looked more closely I could see what looked like a lot of dust floating around. At first I thought it had something to do with the shea, as in maybe it was some kind of impurity. I didn’t want the fats to get any hotter, so I took the bowl off the heat and set it on the stove. After about another 10-15 minutes, the fats were totally clear. All of the “dust” was gone. I’m wondering what the “dust” was that seems to have had a higher melting point.

Here are the photos of the fats with and then without the dust. It may be difficult to see the actual particles in the first photo, but hopefully the clarity of the fats in the second photo is apparent in comparison:

 

[Obsidian]

I can't really see the dust but I can see the clarity in the second picture.
I'm thinking its super fine bubbles from stirring the oils.

For the record, I would have considered the oils melted clear in the first picture. As long as the oil isn't very milky or have chunks, its melted enough.

 

[Millie]

I can't see it clearly enough, are they hard-looking white specks? I always think of them as stearic bits. I don't remember how I came to that conclusion though so it might not be true I always make sure they are melted before I soap, and I have never had a problem with stearic spots.... so maybe...

 

[bookreader451]

I always use a water bath to melt my oils and I see it when I use palm. I think Millie is correct and it is the steric. That is also what I assumed.

 

[Mobjack Bay]

I don’t know if the close up below will be any clearer, but it definitely wasn’t air bubbles. I just found a paper about the stearin fraction of palm (vs. the olein fraction) having more of the saturated FAs and a higher melting point. I’m surprised that it was so easy to see. ETA: and read a little further in the paper that the palm stearin crystals are plate like in shape rather than “spherulitic.” That also matches my observation.

 

[Lin19687]

I use the Microwave to melt, it is just easier and faster for me.
I can't tell you what it is but I melt my stuff to about 140-160. It has a LOT of Palm, PKO, Shea.
Just know that as you cook it, the heat keeps rising a bit after you take if off the stove. Which is why I don't do it that way and I Do Not use a Metal pan - obviously due to the microwave

 

[Mobjack Bay]

Given the smoke points of the oils and butters we use in soap making, I assume they can stand being heated well. I haven’t been keeping track of the temps of my heated oils, but it would be easy enough to add to the worksheet I use to take notes for each batch.

 

[CatahoulaBubble]

Have you tried stick blending your oils? I melt mine in the microwave and then once they are poured into my soap bowl/pot I use my stick blender to mix it up to make sure the oils and any residual stearic is fully incorporated. I don't like to soap if my oils are over 100*F so using the microwave is easier because there's no residual heat from the pot.

 

[Mobjack Bay]

Have you tried stick blending your oils? I melt mine in the microwave and then once they are poured into my soap bowl/pot I use my stick blender to mix it up to make sure the oils and any residual stearic is fully incorporated. I don't like to soap if my oils are over 100*F so using the microwave is easier because there's no residual heat from the pot.

I have only just started using palm at >25% for anything more complicated than a straight pour and I’m still in the “learning everything I can about palm” phase right now. In this case I did not stick blend the oils because I wanted to watch them melt.

 

[CatahoulaBubble]

After they melt just give a good stick blend before adding the lye solution.

 

[shunt2011]

I only melt mine till there is just small bits of unmelted Palm, Lard, Shea etc....then I just stir. If making a large batch I'll melt in my stainless steel pot right on the stove top. My regular batches, I just melt my hard oils as previously stated then add my liquid oils. I always stickblend my oils before adding lye mixture.

 

[DeeAnna]

"...Given the smoke points of the oils and butters we use in soap making, I assume they can stand being heated well...."

I recently learned in a barbecue forum I belong to that smoke point is not a measure of a fat's stability. This misconception is similar to the misconception that the flash point of an essential oil or fragrance oil is a measure of the volatility (rate of evaporation) of the scent.

I know the following quote is from an olive oil industry website so there's probably some bias overall, but the quote agrees with what was being explained in the online discussion about fat stability --

"...An oil’s smoke point does not correlate to its performance and stability when heated. Rather, the factors that predict an oil's safety and stability at high heat are the percentage of polyunsaturated fats (the lower the better), and the extent to which the oil has been refined (the less the better)...." https://www.aboutoliveoil.org/evoo-most-stable-cooking-oil

 

[Mobjack Bay]

@DeeAnna That’s interesting, although it is the olive oil industry promoting olive oil, which makes me want to look for an independent source. As soapers we stay far below the smoke points, and far below the temperatures they apparently used to do the tests reported at the link you provided, which maxed out at 464F and 356F. It’s difficult to extrapolate from there to the temperatures we use for cp. I can’t recall many hp soapers reporting problems with DOS, so do you think we can assume all will be fine if we stay within the temperature range used to make hp soap?

 

[DeeAnna]

"...I can’t recall many hp soapers reporting problems with DOS, so do you think we can assume all will be fine if we stay within the temperature range used to make hp soap?..."

I was only trying to say the smoke point of an oil is not a good measure of stability, just as flash point of an EO/FO is not a measure of volatility.

I don't have any suggestions about what you can assume as far as a reasonable temp range for soaping, whether you do HP or CP. That's going to have to be your call.

I don't recall seeing any info that supports the idea that rancidity is lower in HP soap than in CP soap. My opinion is a lot more people, at least on this forum, make CP soap than HP. Or they talk about it more, at least.

For every 100 CP soapers, there might be 10 dedicated HP soapers, picking numbers at random that seem reasonable. If the comments about rancidity/DOS represesnt 10% of all soapers, then you'll hear 10 CP soapers talking about rancidity versus 1 HP soaper.

Does that mean CP is more prone to DOS? Nope, just more CP soapers to talk about it.​

I already said the quote is from a biased source, but just because an organization has some bias doesn't mean their facts aren't correct. I used the quote because it happened to jive with the information presented by people on my BBQ forum, many of whom work in the food industry or are otherwise educated small-scale pitmasters, and none of whom work in the olive oil industry.

 

[Mobjack Bay]

Thanks for the information @DeeAnna.

In my endless quest for a little deeper understanding, I went ahead and called a marine chemist friend today. She analyzes lipids, including fatty acids, in all kinds of organic matter and marine organisms. Unfortunately for me, she’s working in DC for two years and has not been readily available to answer the many chemistry questions I’ve had since I started making soap. Given that most (all?) of the fats we use have a mix of FAs, her suggestion for minimizing damage to the more fragile components while waiting for the more stubborn parts of the fats to melt is to keep the temperature as low as possible and below 60C (140F) whenever possible. She also said that if heating at a lower temperature for longer is sufficient to melt whatever I’m seeing in the mixture, it would be preferable to using higher heat to melt the fats more quickly.

 

[DeeAnna]

I agree with your friend's advice. My opinion is a lower temp for a longer time can be just as effective (and easier on the fats) as a higher temp for a shorter time.

 

[TheGecko]

I know I’ve been asking entirely too many questions, but please bear with me. I’m trying to learn how to use something other than lard or predominantly soft oil recipes.

Nothing wrong with asking questions, it's how we improve our knowledge.

I thought soap making would be simple...mix fats and lye and waa-la...soap. And it can be that simple...olive oil and lye and waa-la...you have a nice bar of soap...in a year. LOL

But nooooooooooooooo...I can't take the simple route. I want to know why fats and lye make soap. And why some fats are better than other fats and why this combination of fats gets me this kind of soap and a different combination of fats give me a different kind of soap. And when you get into the 'why' you learn about saturated fats, and unsaturated fats, and monounsaturated fats, and polyunsaturated fats. And then there are all those fatty acids...Lauric, Myristic, Stearic, Ricinoleic, Oeic, Linoleic and Linolenic and Gawd knows what else.

Which brings us to melting 'hard' oils/butters. The Melting Point of an oil/butter is the temperature range at which enough fat molecules are melted that the fat becomes liquid. But then there are the fatty acids, the most common of which are Linoleic, Oleic, Lauric, Myristic and Palmitic. Linoleic and Oleic have a lower melting point (19F to 55F) than Lauric, Myristic and Palmitic (110F to 144F). Stearic has the highest melting point at 157F.

Palm Oil contains approximately 50% saturated fatty acids with 44% Palmitic, 5% Stearic and trace amounts of Myristic. So even though the 'melting point' of Palm Oil is 95F, you want to go higher to more evenly distribute the fatty acids (saponification will break down the rest).

On the other hand Cocoa Butter contains 33% Oleic, 25% Palmitic and 33% Stearic. So even though the 'melting point' of it is 100F, it takes longer and/or higher temps to breakdown the Stearic Acid.

But with any oil/butter, you don't want to go too high or you run the risk of thermal decomposition or thermolysis.

Shea Butter is also high Stearic, so I'm guessing that the 'dust' was Stearic.

I use Palm and Coconut Oil, and Cocoa and Shea and this is what I do. I start by heating my bags of Palm and Coconut Oil in a hot water batch in the sink until about halfway melted and then I shake up the bags and/or palpate them well to mix it all up. I then melt my Cocoa Butter, that has been chopped into small bits, about halfway in the microwave and then add my Palm and Coconut until melted. I then add my Shea Butter and stir until melted. I then stick blend my melted oils/butters well. It should be noted that I make small batches...one to two pounds...and this is what works for me based on the size of batches and the wattage of my microwave. When I start making larger batches, I will have to use the stove because my microwave isn't that big and then I will have to start all over again with time and temperature.

 

[Mobjack Bay]

And, it’s even more complicated because apparently many triglycerides (which I recently learned should now be called a triacylglyceride, or is that triacylglycerol? TAG for short) have two or three different fatty acids attached. So, at what temperature does a TAG with one steric, one palmitic and one oleic (SPO) melt? And does the configuration matter, as in PPS vs. PSP? I’m going with “clear on close visual inspection” for as long as my eyes hold out.

 

[TheGecko]

And, it’s even more complicated because apparently many triglycerides (which I recently learned should now be called a triacylglyceride, or is that triacylglycerol? TAG for short) have two or three different fatty acids attached. So, at what temperature does a TAG with one steric, one palmitic and one oleic (SPO) melt? And does the configuration matter, as in PPS vs. PSP? I’m going with “clear on close visual inspection” for as long as my eyes hold out.

I know. Cocoa Butter is 33% Oleic and 33% Stearic, which is a 100F difference. In processing the Stearic, am I destroying the Oleic? But then again, there is the whole saponification process, but on the other side of that is that I refrigerate my GMS so it doesn’t get hot.

I can’t help but think I was better off when I only believed in the magic and was ignorant of the science. LOL

 

[DeeAnna]

...The Melting Point of an oil/butter is the temperature range at which enough fat molecules are melted that the fat becomes liquid.... But with any oil/butter, you don't want to go too high or you run the risk of thermal decomposition or thermolysis....

True statements. I agree.

...even though the 'melting point' of Palm Oil is 95F, you want to go higher to more evenly distribute the fatty acids (saponification will break down the rest).

On the other hand Cocoa Butter contains 33% Oleic, 25% Palmitic and 33% Stearic. So even though the 'melting point' of it is 100F, it takes longer and/or higher temps to breakdown the Stearic Acid....

Shea Butter is also high Stearic, so I'm guessing that the 'dust' was Stearic....

...Cocoa Butter is 33% Oleic and 33% Stearic, which is a 100F difference. In processing the Stearic, am I destroying the Oleic?...

I'm not quite sure you have a full understanding about how fats work. There is essentially NO free stearic acid in cocoa butter. There is just cocoa butter. Ditto for shea. And also for palm oil -- it is palm oil, not a mixture of random free fatty acids. You aren't melting the fatty acids; you're melting the fats.

Yes, there are fatty acids within a fat, but they aren't free to act on their own. When you melt palm oil, for example, and you see some bits that take a little longer or a little higher temp to melt, those bits are FAT that has yet to melt. You don't have to bring the temp up to the melting point of the fatty acid because you aren't melting fatty acid; you are melting fat.

The fat molecules in those bits might have a higher percentage of stearic or palmitic acid than the fat molecules that have already melted, but those fatty acids are still part of the fat molecules. You can't think of them as free actors functioning on their own.

Here's a rough analogy -- You make a batch of those chocolate chip cookies that use M&M candies rather than chips. Each cookie is a fat molecule. The cookie dough is the glycerin backbone. The M&Ms within the cookie are different colors, and each color represents a different fatty acid. Red M&M might be a stearic acid, blue might be oleic, green may be myristic, and so on.

Until these fatty acids are split off of the glycerin backbone by oxidation, heat, saponification or some other decomposition process, they remain part of the fat molecule. To get back to the analogy -- a whole cookie is a whole cookie; it is not a lump of dough + separate candies. If you dig out an M&M from the cookie, then and only then do you have a fatty acid (a loose M&M candy). Until then ... you don't.

Some cookies might have more red M&Ms (stearic acid) than other colors. Other cookies might have more blue or green M&Ms than red, meaning these cookies are higher in oleic or myristic acid. Most of the cookies will be a mix of M&M colors, not just one color alone.

A cookie with more red (stearic) candies and fewer blue or green candies is going to "melt" at a slightly higher temp than a cookie that has more blue or green candies and fewer red candies. But the cookie is still a cookie (a fat) not an M&M (a fatty acid).

Hope I'm making sense!