Goat Milk vs. Water Test Results

Awhile back I made two identical soaps -- with the exception that one used re-hydrated powdered goat milk in lieu of straight water in the lye solution. After almost a 3 month cure, I distributed a questionnaire and a small bar of each soap to 19 blind testers (the soaps were engraved with a 1 or a 2 so they could easily keep track of them). I told them the recipes varied by only one ingredient, but I didn't tell them what that was. Fifteen of the blind testers reported back. In addition to them, I also sent a set to a forum member who knew what the secret ingredient was, but didn't know which bar contained it. This person also reported back, for a total of 16 questionnaires returned to me. I did not take the test myself.

The results are kind of surprising. Most seemed to prefer the water soap. Here's a basic breakdown by the numbers:

Skin Softness: 62% said the bar with straight water left their skin feeling softer, 19% said the GM bar left them softer, and 19% said no difference/can't tell.

Lather: 56% preferred the lather of the water soap, 25% preferred the lather of the GM, and 19% said no difference/can't tell. In optional written descriptions of the lather, many of those who preferred the water soap indicated it was quicker to lather, whereas those who preferred the GM lather generally cited creaminess as the reason they liked it better.

Visual Appearance: 56% reported the GM bar looked more appealing, 6% liked the look of the water soap better, and 38% reported no difference.

Of these, the skin softness answers were most surprising. It's opposite of what I expected. Actually, I take that back... I kind of thought more people would have reported "no difference / can't tell". Most people only used each bar a small number of times before turning in their questionnaires, from what I can tell. For me, it may not have been enough to really feel the difference.

The lather results make more sense to me. The extra fat in the GM bar would weigh down the bubbles more -- requiring more work to get them, and causing them to be smaller / creamier.

This was a very small sample size so not statistically valid. Next time, I would make bigger batches so I could include more testers! But it is interesting for sure. While it might suggest the GM soap didn't have the skin benefits one might expect, it doesn't say anything about label appeal. My guess is that more people would reach for this bar first if they knew what was in it but hadn't yet used it. I don't sell -- but if I did, I wouldn't abandon GM in my line, certainly not without more testing!

What do you guys think of these results?

Thanks for sharing the results. It's interesting. A long time ago I read a discussion about goat milk vs goat milk powder and several people commented GM soap turned out better than soap made with the powder. This makes me wonder what results a comparison of GM to water would produce. I'll have to give it a try but I doubt I'll be able to do it this weekend. Also, I wouldn't be able to come up with as many testers as you had. I'd be lucky to round up 5 people for a test.

Ann Watson in her Milk Soapmaking book described a blind trial she did with soaps made with powdered GM and fresh GM. The testers couldn't tell the difference.

It's important to make sure the powdered milk is mixed in properly. I learned that lesson the hard way. Some bars of soap I made with powdered cows milk have a slightly grainy feel. Not a good thing in a soap that is supposed to be non-exfoliating. :???:

That is surprising! I would have expected the survey to go the other way...

I've found that with powdered cow's milk at least, it needs a good day for the powder to rehydrate. Now, that's mostly based off of my experience using it for cooking or in cereal, but I'm sure it would apply to soapmaking too.

I also can't help but wonder if the soap recipe itself makes a difference. For example, if you know you're using goats milk and its going to weigh down the lather/give creamier lather you make a slight change to the recipe to equalize this. And in knowing the goats milk is going to add superfat, calculate that and lower the superfat* you otherwise would have used. And then compared to the unmodified (so to speak) recipe with water, which would people prefer.... I tend to think the whole recipe and how its put together makes a big difference, thats why I'm working on so many different ones as opposed to perfecting just one. When I get an idea to start out with (goats milk soap, pumpkin soap, etc) I then choose my oils branching off from that idea.

*since you didn't mention it, I'm going to assume you didn't lower the superfat of the goats milk bar so the end result was the same as the water bar.

DeeAnna said:

Ann Watson in her Milk Soapmaking book described a blind trial she did with soaps made with powdered GM and fresh GM. The testers couldn't tell the difference.

Click to expand...

I thought she said there was slight preference for GM as opposed to powder but it was minimal. I'll have to dig out the book and re-read it. Anyway, this was a forum discussion and I can't even be positive I saw it on this forum.

Lin brought up a good point. I do use a lower SF and might use slightly more CO when I make milk soaps. Depends on the milk - if buttermilk, I don't increase the CO but if it's cream, I do increase CO.

If you get your milk from a grocery store, then it's pretty easy to figure out how much fat is in it to add in to your calculations. I'd check the nutrition information for brand-specific information. According to this page though, goats milk has about 10g of fat per cup of milk. So for a soap batch that's 1lb of OO and full water, that'd be 7g (.25oz) of butterfat. Playing around on SoapCalc suggests that this would raise the superfat by 2%. Not a lot, but enough for some people to notice a difference.

I'm not really surprised by this. I've used a few different animal milk soaps, either what I've made or what I've gotten from swaps and I didn't really like any of them. The difference in lather is minimal, to the point of not really being able to tell there is a additive. I also see no difference with beer soap vs water but coconut milk soap has noticeable creamier lather.

I do see a difference between beer and water. Maybe it's because I don't use a large percentage of CO. I also find milk soaps to have a silkier feel. Just shows the differences between people. :grin:

I used the same recipe that another forum member developed specifically to conduct her own gm test, and it seems well suited enough. Since it's not my recipe I don't feel I can share it, but Lin, if you could lend more detail on your comment about composition, that might help me judge better.

The lye discount relative to the soaping oils was identical in both bars -- 6%. In my eyes, it was important to control things tightly and keep everything else (including superfat) the same. The GM added fat at the rate of a little less than 1% of the weight of the soaping oils. I don't think that translates directly to a 1% increase in lye discount, but it's pretty close. That was using the reconstitution rate recommended on the can.

About the powder potentially not being fully dissolved... I can't say for sure but it doesn't seem like that would have been an issue. When mixing powder, I always use hot water and stir it multiple times as the solution cools to room temp. For this batch, I then froze the milk and later added the lye to the cubes (as opposed to adding gm to the oils like I sometimes do). As a standard practice, I always make sure the lye solution is clear (everything fully dissolved) before adding to the soaping oils. It may be a little harder to tell with GM in lye since the solution saponifies/gels a little. Well anyway, I can't be 100% sure now but there were no comments that either soap was scratchy, and I personally haven't experienced that in any of my gm soaps.

As for using powdered/re-hydrated gm verses canned or fresh milk, that was very intentional on my part. Powdered is so much more economical, I figured it would be best for me to know whether this form would make a positive difference or not. I thought about making a third batch with the real deal, but decided that would just be too complicated for the testers (and I had seen the results already mentioned as well). But I'd be really interested in anyone else's tests!

I have two ideas why it might have turned out this way: 1. people were biased by the difference in lather (people like lather!), or 2. There really was no difference in the gm rate used, and the sample size wasn't big enough to draw that out. Or maybe I'm being short-sighted in not accepting the results more directly roblem:

CaraBou -- I sincerely thank you for being so generous about sharing your test results. I know it can sometimes be a bit difficult to deal with the questions, comments, and second-guessing after all the planning, work, and thought. I appreciate your willingness to put yourself out in the public eye. Kudos to you!

This thread was very interesting, and thanks so much for sharing. I know too many people who are vegan, and was wondering if I should even bother with goats milk. I also wondered about tussah silk, and received a soap made with it from a recent swap. While I feel the difference, I'm not sure it's important enough to start adding. I'm still in my first year of soaping, so all my batches are experiments. Thanks for the time you put into this study.

Thanks guys. I wish my results were easier to understand, but it is what it is. I really wanted to get back all of the forms to make the results more meaningful -- hence I kept prodding & waiting for the straggling few -- but at this point it just needed to be reported so the curing wasn't a factor. But if anyone goes through developing a test like this, I encourage bigger samples. These batches had 1,000 grams of oil and netted 20 small bars apiece. In a stats class I took a looooong time ago, they talked of 25 being a minimal sample size to be able to infer anything. I just went with what my 2 biggest mold (and equal sized) molds would hold.

Thanks, CaraBou! I'm sorry I missed this update on the test until now. I'm really appreciative of all the hard work you put into this. I think your results were pretty telling! If nobody else runs another test with goat milk soaps I'd like to do one at some point in the distant future. Might be challenging since my base recipe can only contain some mix of any of the following: coconut/olive oil/shea butter/cocoa butter/avocado oil/sunflower oil/castor oil/rice bran oil.

thinkativone, your list contains all of the oils that I used in this test. It was comprised of your first three oils and the last two. There was no lard, tallow or palm. As mentioned above, it is not my place to state the exact recipe since someone else graciously shared what she developed for a near identical test across the Atlantic (I believe the only difference was that she used fresh GM). But I can say that all of the recipe's quality values (for hardness, conditioning, bubbly, creamy, etc) fell within SoapCalc's suggested range.

Part of the point of testing a recipe, I think, is to see how it works with the other ideas & values you have for a soap. For example, I used powdered GM because I knew fresh GM would be too cost prohibitive for me to use on a regular basis (I spend enough on my hobby soaps the way it is, lol). I specifically wanted to know if the economical version would lend anything to my soap. And at the time, I had just given up PO and had not replaced it yet with lard or tallow, so the "replicated" recipe suited me well. If the list of oils you provided is what you normally soap with, I'd say go for it, use them in your own test batches. There is so much flexibility with soaping, and rarely a right or wrong way, so go with what works for you!

How cool! I would never have guessed it was comprised of those ingredients. Right now all I have are coconut oil/olive oil/shea butter/sunflower and a scant amount of cocoa butter, but the rest of the oils are readily available to me. You are so right about the flexible nature of soaping. I'm greatly encouraged that you've had such success without palm and animal fats. On my list to experiment with next is probably going to be a himalayan salt bar. I have a 22 lb. bag of the salt coming my way.

I can understand why you would choose to use powder. If I can come up with a good base soap for the test I would use fresh goat milk - but then I live in Washington where it's legal to sell raw milk at grocers. It's readily available here (often 3 different dairy brands in one store to choose from) so it shouldn't be too costly.