Dairy butter and odour

[ResolvableOwl]

I'm a bit puzzled over the strong reactions that mentioning dairy/milk butter as a soaping fat has evoked in another thread.

There is that mentioning of a “vomit” smell that the soap would exert and leave on the skin.
In contrast to this, my own experiences with cow's milk butter were a lot less dramatic. One batch made from pure butter (i. e. with residual buttermilk etc.) had an ammoniacal/fishy odour for a few weeks (from decomposing proteins), but after that had gone, the smell was not exactly unpleasant at all even after months of curing. Slightly cheesy at worst, and definitely nothing sticking on the skin I would be alarmed about. I don't know if I would dare give it away, but the natural smell of the soap wouldn't be the most important reason for this. In another recipe, I put 50% butter (pure butter fat), and I didn't notice anything special about it. After curing, it was easier to distinguish from a different test batch by its colour, not its odour.

Did I just have luck? Or is there quite some exaggerated alarmism and thoughtlessly passed-down urban myths (or worse) floating around for dairy butter in soapmaking? Are there any good sources for that “vomit smell” story? Yes, butter is partly made up from butyrate, and butyric acid smells like vomit, but a soap isn't supposed to consist of free fatty acids, but their (non-volatile, hence odourless) salts. To add another perspective: everyone is putting tons of coconut oil and goat milk in their soaps, with mid-chain fatty acids (caproic/caprylic/capric) at much higher levels (15%) than the 3…4% of butyric acid in cow's milk butter. These don't exactly smell pleasant either, but where are the complaints about them … ?

I cannot and do not want to question experiences from others, but in return I expect everyone to keep up some healthy level of professional confidence into evidence. There is just no way how some random hearsay can invalidate contradicting experiences, this simply helps nobody. Each advice and every warning likely contains some scientific rigor, some artisan's experience, and some dubious esotericism – and each time we have to decide how we like to balance these.

 

[AliOop]

Rather than accusing people of "random hearsay," you might want to use the search bar above to confirm actual experiences and experiments that have been recorded by members of this forum. Quite a few have tried butter in their soap, and we all concur about the horrible smell.

Perhaps we cannot offer a scientific explanation for why butterfat in our soap smells bad, why other oils do not, or why you did not experience that with your soap. But neither can you explain why your experience is different from everyone else's. Yet you consider others' statements based on experience to be "hearsay," whereas your statement based on experience is considered "evidence." Quite the double standard there.

Telling us that you "expect everyone to keep up some level of professional confidence" insinuates that we are being unprofessional to speak of any experience that differs from yours. That is very interesting, considering that your outcome with using butter in soap is most certainly the outlier - which you can confirm if you will take the time to do a little reading.

Statements like those you posted above, and elsewhere, are not in keeping with the truly professional (and kind) tone that we use with one another in this forum.

 

[KimW]

I'll chime in. I suspect there are a few here on SMF who have made soap with dairy (cow's milk) butter, and I'm pretty sure I recently read an old post where someone described the experience in detail.

I've made soap from dairy butter and, while I wouldn't describe it as smelling like "vomit", it was a most foul smell. You described it as a cheesy smell, and I would also describe it more as such - perhaps combined with "stinky wet feet shoes". Not sure if you know the smell I speak of here. It might be a purely USA thing from swimming in lakes and ponds during very hot summers. There's an awful putrid smell that happens when you wear shoes with wet feet in hot weather. There's no other smell like it that I've found. It can stink up a whole house for days and the shoes are usually ruined because that smell rarely goes away. You'll think it's gone, and then, BAM, you're out to dinner with friends and that smell comes wafting up from under the table... ANYWHO - Combine that with Gorgonzola cheese, and that's the smell I remember from dairy butter soap. The smell did get less "strong" over time, but it was no less putrid, and once wetted and lathered you could once more smell it from a few feet away. As far as the smell remaining on hands, the smell did remain.

There ya go - my 2 cents.

Maybe German cows produce more dainty milk than USA cows?!

@AliOop - do you knoweth the stinketh of which I speaketh?!

 

[AliOop]

@AliOop - do you knoweth the stinketh of which I speaketh?!

Yes ma'am, I most certainly and unfortunately do

 

[Iluminameluna]

Wow. I have tons of butter. And lard. Maybe I will make a tiny, TINY, bar of it just to see what happens.
I'm housebound in Texas. What else am I supposed to do? Oh, wait, crochet. Right.
I've also been making soap coasters. For the rancid soap I'll make something dainty.

 

[ResolvableOwl]

I was in some rage when I posted this. Please be indulging. I somewhat took it serious to follow the advice and collect experience (in this case mine), and compare it to that of others. Should I not have done this? Something didn't make sense to me, I asked for clarification, and now I somehow have to deescalate things and try to smooth out accusations of rudeness and tactlessness. Not what I have come here for, but I'll give it a chance.

I don't see where my behaviour is double standards, feel free to explain it to me! Your word against mine. That's the reality, and reality is not democratic: you can drown opinions, but not facts. I simply cannot tune in, in good confidence, into the “the world will end if someone puts dairy butter into soap again”, or what would you like me to say to be satisfied? We are faced with a “You might have luck, or you might not” situation, and we somehow have to deal with it. Be constructive, I am attempting to be constructive as well.

Once again: I am not questioning all those terrible experiences! But I have reasons to believe that there is more to the butter-in-soap story than these. Better reasons than being told by internet strangers to shut up. I don't want to block the twisted pathways of curiosity, for whatever reasons. I am at any time ready to step out of my comfort zone. If you have reasons to defend yours against conflicting evidence, I'm paying full attention. But expect that people will correctly identify this as theology then. Nothing wrong with such faux dialectics, but then I'm out, since I have learned to avoid these discussions; in my approach to soapmaking, theology has no place.


Maybe @KimW is into something, and it really is connected to what the cows have eaten. For my most recent batch, I used organic clarified butter from (as far as the label tells) a dairy in Munich, Bavaria. Happy cows grazing in alpine pasture, monotonous stable tristesse, or both? We don't know.
I'm not a specialist as it goes to cattle food regulations under organic agriculture, but there are some (I know that silage and GMO concentrates are forbidden, and there is a minimum share of food that a farm has to grow by themselves). Impact of diet and housing conditions on what is in the milk is well-known (focus of scientific literature is on ω-3 fatty acids and vitamins). Whatever causes the stinky escalation of some (perhaps most, but definitely not all) the butter out there, is probably highly variable as well.
Logical steps for someone to explore this further: a series of butter soaps, covering a reasonably representative sample of global habits of milk production. Identify the “stinky” ones and test, maybe via gas chromatography, for the chemical culprit(s). Analyse the butter and search for precursors therein. Once we know how these came into the milk, we have found some positive result, and some advice for future courageous soapers where to source their dairy butter from.

 

[cmzaha]

I am one of those that experimented with several types of butter several years ago and different EO's to mask the odor. Although some did not initially leave a bad odor the odor was highly detectable after washing and rinsing off the soap. So please do no say it is hearsay, it was a fact and it was not just from me. This test was actually started with soapmakers in another forum with is now defunct. It stunk, did it smell like "vomit", to some yes, to me maybe, but it was just plain nasty smelling on my hands.

ETA: We tried various Ghees, butter brands etc. They all had the same results for the group of us that tried butters, organic and non-organic brands.

 

[KimW]

I think, perhaps, your original post went awry in the last paragraph, especially the phrase "random hearsay". I can only say, I have an Oma. You might understand, but that is no matter.

Until the last paragraph, your post was fine and even included the phrase "Did I just have luck?" Prior to the last paragraph your post appeared to be asking if there was actual experience with dairy butter soap being unacceptable. While it's unfortunate that a simple search on SMF for butter soap would have negated the statement, "Or is there quite some exaggerated alarmism and thoughtlessly passed-down urban myths (or worse) floating around for dairy butter in soapmaking? Are there any good sources for that “vomit smell” story?" even with this, your post might have been regarded as curiosity and you might have just received links to various threads where folks had indeed experimented with dairy butter soap and had indeed experienced soap that could not be used or at the least, as you say, could not have been given away/sold. You might perceive the many replies of dairy butter soap as smelling like "vomit" to be...too absolute and contrary to your experience, but is it necessary to suggest they are thoughtless? Still, since you worded it as a question it might have had a different reception.

Yes, I think if you had left it there and left out the final paragraph, the responses might have been different.

Also, it may be worth noting that a soap's properties, be it cleansing or drying or smelling (good or bad), is a subjective matter. That is, it's a matter of opinion and personal preference and even skin type. I hate the smell of patchouli essential oil which is popular in soaping - not as much as "stinky wet feet shoes", but it's close. Other people, many people, adore the smell. If I might be quite my American self for a moment, here's the dealio-yo: If I liked patchouli, or at least didn't find it very offensive, I might suggest to someone who hated it to try a better brand of patchouli, but I'd "never" suggest that folks claiming patchouli smells foul (which it absolutely does to me) were being thoughtless or repeating "random hearsay". Kapiert?

 

[Peachy Clean Soap]

Interesting topic' im gonna look up Using Dairy & Its effects?. Now to play the Devils Advocate Here' I've use Full Cream in my soaps 1oz PPO w/ wonderfull results ( so I thought?) im gonna recheck my soap' I may have some stinky soap onboard. Yikes.

 

[AliOop]

@Peachy Clean Soap cream is fine. It is butter, specifically, that creates stinky soap.

@ResolvableOwl to be very clear, I am not telling you to shut up at all. I welcome your questions and curiosity like I would those of any other member, and in the same way that I hope my own questions and curiosity are welcomed.

What is not welcome is how you -- also an Internet stranger to me and others here -- are wording your questions and statements. I will choose to believe the best about you: that some of this is a language issue (that's a guess bc you are in Germany), and that you truly have no idea how offensive several of your posts have come across to the rest of us. Because this is not the first time your questions have been stated in such a way as to insult the intelligence and experiences of other members here.

@KimW gave a good explanation of how and why your statements above were so offensive, so I won't go into that further. Just know that this group would like to welcome and include you. Unfortunately, your wording choices have been, and if unchanged, will continue to interfere with that process.

To say it another way: It is not WHAT you are saying that offends, it is HOW you are saying it.

 

[Peachy Clean Soap]

@Peachy Clean Soap cream is fine. It is butter, specifically, that creates stinky soap.

Thx for your 411 appreciate it Dear.

 

[DeeAnna]

Fatty acids such as butyric (butanoic acid, C:4), caproic (hexanoic acid, C:6), caprylic (octanoic acid, C:8), and capric (decanoic acid, C:10) all have an odor. The C:6 through C:10 fatty acids are present in nut oils such as coconut oil, babassu oil, and palm kernel oil.

Of the fats I've studied that are typically used in soap making, milk fat (butter fat) is the only fat that contains a significant amount of butyric acid, however. The butyric acid content is in the range of 2-4% in milk fat from cows and goats. (3)

The odor of butyric acid (C:4) is also detectable by humans at much lower limits than the smell of the other fatty acids mentioned in this post.

One source reports humans can detect butyric acid in the air at 0.26 ppb (parts per billion) by volume. Detection limits in the same study for caproic/hexanoic acid was 1.0 ppb and caprylic/octanoic acid was 0.86 ppb. (1)​

It isn't just the detection limit, however, that is important here. In addition to being easier to smell, butyric acid also has a much more offensive odor than the other fatty acids I've mentioned.

Butyric acid contributes to the characteristic odor of vomit, since butyric acid is formed in the gut. In research done on controlling odors from livestock confinement facilities, butyric acid has often been used in chemical mixtures designed to simulate the pungent, offensive odor of hog wastes. (2)​

(1) Structure–activity relationships on the odor detectability of homologous carboxylic acids by humans
(2) http://northeast.manuremanagement.c..._Nuisance-from_Livestock_Buildings_Part_3.PDF
(3) Fatty Acid Profile in Goat Milk from High- and Low-Input Conventional and Organic Systems

***

...cream is fine. It is butter, specifically, that creates stinky soap.

I don't think this is truly correct, Ali. Cream contains milk fat, therefore cream also contains butyric acid. Remember that butter comes from cream! This is true for dairy butter and any dairy milk that's not skimmed (fat free).

The key point using dairy is to look at the percentage of butyric acid present in the soap from whatever source of milkfat you use.

If full fat cow's milk (3.5% milkfat) is used as a full water replacement in a typical soap, the milkfat added is only 1% of the total fat used to make the soap. Assuming butyric acid is 4% of the milkfat, that puts butyric at 0.04% of the total fat. I'd say this small amount of butyric is unlikely to contribute much if any odor to the soap.

If heavy cream (aka whipping cream, 35-40% milkfat) is used as a full water replacement, the milkfat supplied by the cream would contribute around 15% of the total fat in the soap and the butyric content in the soap would be 0.6%. This amount of butyric might cause a detectable odor for some noses.

If butter (approximately 80% milkfat) is used as 20% of the fat in a soap recipe, the milkfat would be 20% of the total fat in the soap and the butyric acid content would be roughly 0.8%.

Having made soap with enough butter to contribute 16% milkfat, I know the butyric acid does contribute odor to the soap at this level. I would expect the odor to be stronger as the percentage of milkfat rises. This particular soap had a definite cheesy odor that did not go away during cure. I didn't hate the odor, but I didn't enjoy it either. I used part of a bar, and then discarded the rest.

***
The other issue that has not yet been mentioned in these kerfluffles is that fatty acids with fewer than 14 carbon atoms in their backbone make a soap that is known to be more irritating to the skin. These shorter-chain fatty acid troublemakers include butyric, capric, caproic, caprylic, and lauric acids (C:4 through C:12).

The lauric (~46%), caprylic (~8%), and capric (~8%) acid levels in coconut oil are the main reasons why coconut oil soap is so drying and harsh to the skin. And this another good reason to not add a lot of milkfat to soap either.

 

[KimW]

Ah-ha! Finally a scientific answer to why coconut oil soap is drying. Thank you, DeeAnna!

ETA: Coconut oil soap is not drying to hubs, but olive oil soap is. I am the exact opposite. While olive oil soap does cause a tightness to my skin, it's not drying like CO soap. I can smell the "freshness" of unscented soap, he can't. To him, there's just no scent. Ah, humanity.

 

[AliOop]

DeeAnna, I was hoping you would weigh in with the science here - thank you! I have used cream before with no issues, but then again, I don't have the strongest sniffer in the world.

For instance, two of our daughters can detect the odor of small amounts of specific ingredients from a mile away, whereas I would be blissfully ignorant thereof. My post-COVID olfactory abilities are even worse, although slowly improving with time.

The fact that, like @ResolvableOwl, you also found the butyric acid smell to be "cheesy" rather than "vomit-like" suggests that at least part of the difference in outcomes arises from the differences in the way individuals experience smells. I liked @KimW's analogy to patchouli, which evokes a love-it or hate-it reaction in most people, with very little middle ground. Neither the patch-haters nor the patch-lovers are right or wrong; they just experience it differently.

 

[Peachy Clean Soap]

Fatty acids such as butyric (butanoic acid, C:4), caproic (hexanoic acid, C:6), caprylic (octanoic acid, C:8), and capric (decanoic acid, C:10) all have an odor. The C:6 through C:10 fatty acids are present in nut oils such as coconut oil, babassu oil, and palm kernel oil.

Of the fats I've studied that are typically used in soap making, milk fat (butter fat) is the only fat that contains a significant amount of butyric acid, however. The butyric acid content is in the range of 2-4% in milk fat from cows and goats. (3)

The odor of butyric acid (C:4) is also detectable by humans at much lower limits than the smell of the other fatty acids mentioned in this post.

One source reports humans can detect butyric acid in the air at 0.26 ppb (parts per billion) by volume. Detection limits in the same study for caproic/hexanoic acid was 1.0 ppb and caprylic/octanoic acid was 0.86 ppb. (1)​

It isn't just the detection limit, however, that is important here. In addition to being easier to smell, butyric acid also has a much more offensive odor than the other fatty acids I've mentioned.

Butyric acid contributes to the characteristic odor of vomit, since butyric acid is formed in the gut. In research done on controlling odors from livestock confinement facilities, butyric acid has often been used in chemical mixtures designed to simulate the pungent, offensive odor of hog wastes. (2)​

(1) Structure–activity relationships on the odor detectability of homologous carboxylic acids by humans
(2) http://northeast.manuremanagement.c..._Nuisance-from_Livestock_Buildings_Part_3.PDF
(3) Fatty Acid Profile in Goat Milk from High- and Low-Input Conventional and Organic Systems

***


I don't think this is truly correct, Ali. Cream contains milk fat, therefore cream also contains butyric acid. Remember that butter comes from cream! This is true for dairy butter and any dairy milk that's not skimmed (fat free).

The key point using dairy is to look at the percentage of butyric acid present in the soap from whatever source of milkfat you use.

If full fat cow's milk (3.5% milkfat) is used as a full water replacement in a typical soap, the milkfat added is only 1% of the total fat used to make the soap. Assuming butyric acid is 4% of the milkfat, that puts butyric at 0.04% of the total fat. I'd say this small amount of butyric is unlikely to contribute much if any odor to the soap.

If heavy cream (aka whipping cream, 35-40% milkfat) is used as a full water replacement, the milkfat supplied by the cream would contribute around 15% of the total fat in the soap and the butyric content in the soap would be 0.6%. This amount of butyric might cause a detectable odor for some noses.

If butter (approximately 80% milkfat) is used as 20% of the fat in a soap recipe, the milkfat would be 20% of the total fat in the soap and the butyric acid content would be roughly 0.8%.

Having made soap with enough butter to contribute 16% milkfat, I know the butyric acid does contribute odor to the soap at this level. I would expect the odor to be stronger as the percentage of milkfat rises. This particular soap had a definite cheesy odor that did not go away during cure. I didn't hate the odor, but I didn't enjoy it either. I used part of a bar, and then discarded the rest.

***
The other issue that has not yet been mentioned in these kerfluffles is that fatty acids with fewer than 14 carbon atoms in their backbone make a soap that is known to be more irritating to the skin. These shorter-chain fatty acid troublemakers include butyric, capric, caproic, caprylic, and lauric acids (C:6 through C:12).

This is the main reason why coconut oil soap is so drying and harsh to the skin -- coconut oil contains a high amount of lauric acid. And this another good reason to not add a lot of milkfat to soap either.

Love your info' wow!! makes perfect scents ( scientifically ) Much Appreciation. Another SS I don't want to loose your info. .

 

[DeeAnna]

In response to the statement that "...a soap isn't supposed to consist of free fatty acids, but their (non-volatile, hence odourless) salts...", I'd like to make this comment --

Some products of chemical reactions are odorless and some are not. And even if the reaction products are odorless in theory, that finding doesn't necessarily hold true in the real world.

I have no way to learn conclusively if perfectly saponified butyric soap has an odor or not. What I do know from personal experience is fresh dairy butter doesn't have a distinctive cheesy "butyric" odor, but real-world soap made from said dairy butter does (see my previous post).

The presence of this odor in my soap, combined with the comments from other people who have observed similar "butyric" odors in their soap means one of two things -- (1) Butyric soap does indeed have a characteristic "butyric" odor (I'm taking a hard pass on testing this hypothesis) or, what's more likely, (2) there is some residual free butyric acid in the soap after saponification is complete.

Given we usually make soap with some superfat and given that butyric acid has such a strong offensive odor with such a low detection limit, even trace amounts of butyric acid in soap are likely to create detectable odor, even if the butyric soap itself happens to be odorless.

 

[ResolvableOwl]

To say it another way: It is not WHAT you are saying that offends, it is HOW you are saying it.

I can't help myself but apologise for a harsh perception of my wording! I am sorry, I did not want to offend anyone. Please understand, that, although it might be your experience, it is still your experience, and so from my perspective it is not first-hand evidence but merely anecdotal. I'll have to believe you, and somehow combine this with my contradicting first-hand observations, and nobody would help me with that (and publication bias working against me). Maybe you understand why I am so puzzled. I would have been happy with a statement like “Hey cool, yes, you might be in luck, but overwhelmingly bad experiences with dairy butter led us to discourage its use in soaps – better safe than sorry”, but I didn't expect (as I perceived it) unwillingness to give up beloved prejudices about that ingredient.

However, to come back to the factual topic, I appreciate some scientific grounding. Noses are different (look at the order of magnitude of spread between test persons in DeeAnna's link (1)), butter sources are likely different, soapmaking protocols are different, perception profiles of fatty acids are different.

Some products of chemical reactions are odorless and some are not. And even if the reaction products are odorless in theory, that finding doesn't necessarily hold true in the real world.

I have no way to learn conclusively if perfectly saponified butyric soap has an odor or not. What I do know from personal experience is fresh dairy butter doesn't have a distinctive cheesy "butyric" odor, but real-world soap made from said dairy butter does (see my previous post).

There might be a way, though: pure sodium butyrate. I don't happen to have that at hand, but I do have access to a bottle of >99.5% analytical-grade sodium acetate instead. I gave it a try and inhaled deeply from it – only the slightest trace of vinegar smell, if at all (gosh, another anecdotal experience!).
If one divides out that order of magnitude that acetic acid is less easily to detect than butyric acid (though odour threshold ≠ odour strength complicates things even more), and another order of magnitude for if I happen to be particularly insensitive towards butyric acid (which I don't think is the case), the numbers are down at roughly that one-percent butyric range which comes with sensible dosage of dairy butter in soaps. My conclusion: there is a very low chance for sodium butyrate (itself) to impact smell of a soap.

That of course does not rule out superfat/incomplete saponification, and the plethora minor impurities. As I already reported, the main smell of my butter soap wasn't “rancid butter” but ammonia. Also during skin contact, some of the soap anions will exchange protons with the so-called acid mantle. Another chance for free butyric acid to develop (risk of false negatives). To make things worse, false positives might be hidden when C:4 isn't the only culprit in the smell issues with butter soaps.
But this is a question left for someone with thorough stamina to crawl through scientific literature and/or a gas chromatograph. For now, I for my part am satisfied when we can agree that not all combinations of dairy butter soap and its users, are created equal.

 

[DeeAnna]

...The fact that ... you also found the butyric acid smell to be "cheesy" rather than "vomit-like" suggests that at least part of the difference in outcomes arises from the differences in the way individuals experience smells....

I would agree with you on this point. The way a particular person's nose works can make a big difference. I can't say my nose is greatly different than the average person's, however. My ability to smell and taste are about the same as other people's.

It's my guess that life experience is the main reason why I might have a different perspective about odors. As a teen, I did chores on my grandfather's hog farm, and my first decade of adult life was spent working as an engineer in chemical production plants.

Once a person understands the intensity of "piggy smell" from mucking out hog pens by hand or the pervasive scent of an industrial wastewater treatment plant, then a light whiff of butyric acid in a bar of soap is merely "cheesy". I might not care much for the odor, and I can appreciate why I wouldn't want it to be any stronger than it is. But I'm not going to insist it's intolerably nasty, because I don't see it that way. I've learned there are far more nasty odors out there.

I also tolerate the odors of neem and pine tar soap fairly well, and probably for much the same reasons.

 

[KimW]

I've learned there are far more nasty odors out there.

Patchouli! Patchouli is more nasty!

 

[violets2217]

Patchouli! Patchouli is more nasty!

And Neem Oil! Nastiest smelling oil every!! I enjoyed throwing my one bottle out after I found it hiding in the back of the cabinet 2 years later!