Milk soap questions - and why doesn't it go "bad"?

[Patty88]

Hi all,

Please forgive what I'm sure is a novice question, but my Google-fu was coming up short. How can one make a soap with goat's milk, cow's milk, etc. and not have it go rancid? I'm just thinking of every other milk-based product I've ever consumed, yogurt, cheese, milk, etc. they may last quite some time but they all have an eventual time when they go "off", even cooked milk products. I've been trying to find the science behind it but no luck so far.

I'm doing a "DIY" Christmas this year and making 3-4 soaps to give out in little gift packages - I'd like to make a goat's milk and honey soap for my family and friends but I'd be absolutely horrified if it would go rancid after I give it to them after the 6-week cure time.

If I do go for it, is there any reason why I can't use store bought goat's milk or does it need to be raw for whatever reason? I'm sure I could get straight from the farm goat's milk around here, I'm just not sure who to ask. However I did see goat's milk at Walmart so if that will work, I'll do that.

Last but not least, how do you all scent your milk soaps? I would like to do a scent in this but I don't know what would go well. I'm thinking of doing a lavender/citrus blend, a coffee soap, and a mint soap besides to give out. Almond sounds nice, maybe a coconut or floral for something different from the other soaps. What have you had good luck with?

Thank you!

 

[dixiedragon]

I don't know the science, but it does work. I've used dairy, fruits and veggies in my soap and not had them go rancid. I have had some start to show rancidity (DOS - dreaded orange spots) after a year or so, but I've also had that with soap with no milk or veggies.

You can use store bought. I actually recommend canned vs fresh, because it's had the water removed. That way, you dissolve your lye in water and let it cool, and don't risk the sugars in the milk burning, but you have the same amount of milk - meaning the same amount of proteins, fats, etc, just with less water in the milk itself.

I use the milk in oil method.
https://www.lovinsoap.com/2013/02/t...d-honey-cold-process-soap-milk-in-oil-method/

I reduce my amount of water by the amount in the can. Mix water and lye and let it cool. Heat oils on the stove until they are melted, then let them cool to 100. This part depends on the oils - some have a higher melt temp and this wouldn't work. I use lard - you would need to soap a bit hotter if you are using tallow or palm. When lye water is room temp and oils are 100 or so, add the milk to the oils. I also like the add the fragrance at this stage. Blend with the stick blender as you slowly pour the lye water into the oils.

I don't make a lot of milk soap - I always catch a sour milk note from it, even from other people's milk soaps. Scent wise, you can do anything - the milk will make the soap off white or tan, so don't go in expecting to do a WHITE color scheme. scent wise, you can do whatever you like. I tend to like to scent on the stronger side anyway, so I pick "dark" scents that are heavy and rich to cover up that sour milk note. Vanilla, anything spiced, etc.

 

[TheGecko]

How can one make a soap with goat's milk, cow's milk, etc. and not have it go rancid? I'm just thinking of every other milk-based product I've ever consumed, yogurt, cheese, milk, etc. they may last quite some time but they all have an eventual time when they go "off", even cooked milk products. I've been trying to find the science behind it but no luck so far.

Just like how the lye breaks down oils/fats into fatty acids and glycerin during the saponification process, it does the same with milk as the principal constituents of milk are water, fat, proteins, lactose (milk sugar) and minerals (salts).

If I do go for it, is there any reason why I can't use store bought goat's milk or does it need to be raw for whatever reason? I'm sure I could get straight from the farm goat's milk around here, I'm just not sure who to ask. However I did see goat's milk at Walmart so if that will work, I'll do that.

I use Meyenberg Goat Milk, it's in the 'baking' aisle, usually top shelf next to coconut milk. I pour it straight out of the can into an ice cube tray and then double bag it in my freezer. When it's time to make soap, I measure half of my distilled water weight with the frozen cubes and the other half with frozen distilled water plus a little room temp distilled water. I then put my container in an ice bath...I use ice cubes from two trays, two cups of water and a tablespoon of salt...and then slowly pour in the lye in small amounts until it is dissolved and then add more. This keeps the lye from scorching the milk (because of the sugars) and turning it brown. I soap GMS at around 70-75F. The goat milk and lye solution will thicken up a bit as the lye starts to break down the milk, but it's okay. After pouring in the mold, I refrigerate the soap for 18-24 hours and then let it come to room temperature before cutting (cold soap is slippery).

Last but not least, how do you all scent your milk soaps? I would like to do a scent in this but I don't know what would go well. I'm thinking of doing a lavender/citrus blend, a coffee soap, and a mint soap besides to give out. Almond sounds nice, maybe a coconut or floral for something different from the other soaps. What have you had good luck with?

You can use anything you like. So far I have used Honey & Oats, Vanilla Bean, Pearberry and Black Raspberry Vanilla. I also used Rose Milk, but didn't care much for it, but my daughter likes it.

 

[cmzaha]

Your questions were answered as to the use of milk in soap, now I will ask are you new to soapmaking? If so are you going to make cold process soap (cp) which is the lye method of making soap or are you going to use the melt and pour method of making soap? If making m&p I highly recommend you use a quality Goat Milk base such as one from Essentials by Catalina. This is the one my daughter always used and it is a lovely base. Some additives in tiny amounts can be used and will tell on their website. They make their bases in-house and are lovely.
https://essentialsbycatalina.com/goat-s-milk-melt-pour-glycerin-soap-base

 

[dndlyon]

In general, there are 2 things that make milk "go bad".
1 - Enzymes (naturally occurring in lots of foods) break down proteins and fats in the milk. The by-products of these reactions (the chemicals left over) can be stinky. Proteins that are broken down can stick to each other - causing the milk to thicken up.
2 - Microbes - bacteria, mold, yeast - (also naturally occurring in lots of foods) break down milk components and produce waste products that make stinky, gross milk. [In case you are thinking, "But milk is pasteurized (or UHT outside the US)!" - Pasteurization doesn't kill everything, and once the package is open, the microbes will play - yay for refrigeration!]

We can use food stuff in soaps and it won't go bad for a few reasons - the primary one being the process itself. There is a lot going on, but to simplify it - the pH and temperature during the process is pretty unfriendly to both the microbes and the enzymes present in the food stuff. Also, microbes need water to grow and spoil things. The final soap bar has a very low amount of "free water", so the final bar is not a happy place for microbes.

You can search through the forums a bit and google to see posts about soap going wrong with food ingredients (for example, I've seen a few blog posts where a food puree wasn't mixed well enough so 'food pockets" formed in the soap and mold grew). Food can spoil soap, but if you mix well, and use the right ratio of food to soap, you should be good.

(Edited to add: I'm only speaking here about cold process, lye based soaping. I have only limited experience with melt and pour, and a few people made some very good points at the same time I was typing )

 

[IrishLass]

Carolyn brings up a good point^^^^. My sis had a friend that used to make goat milk soaps using Melt & Pour soap base. She would add fresh goat milk from her goats directly to the melted M&P base. According to my sis, those M&P goat milk soaps always went bad, and it didn't take very long to so so. As a matter of fact, my sis was never able to use up an entire bar. They always went bad after about a week of use and she'd have to throw it out. I had the misfortune of using a bar of one of them once while at my sis's, and I ended up having to wash my hands with a dish soap after washing my hands with it because it left an yucky rancid smell behind on my hands.

If you are making lye-based soap with the goat milk, however, you'll have no problems because the lye reacts with it and helps preserve it, so to speak.

When it comes to making goat milk soap (lye-based CP), my personal milk preference is fresh, refrigerated goat milk mixed with enough powdered goat milk to bring the concentration up. Years ago, I used to use the canned concentrated Meyenberg, which does make for a nice soap, but I switched to using fresh mixed with powdered because I didn't like the tan color that the canned concentrated type always gave to my soaps. With my fresh milk/powder mixture, my goat milk soaps always end up a nice, light, off-white color instead of tan/brownish....and if I use a little TD, I get a nice shade of white. The fresh goat milk that I use is the Meyenberg-brand that can be found in a carton in the refrigerated section of the grocery store. We drink whatever fresh goat milk is left over from making soap (yum!)

When I make my goat milk soap I use the 'split method' in order to avoid mixing any of the lye directly with the milk. Basically, with the split method, the water amount required for the batch of soap gets split up. One part gets mixed with lye (an equal amount of water in weight as per the weight of lye), while the remaining amount of required water is subbed as fresh goat milk into which I've mixed a certain amount of powdered powdered goat milk, which then gets stick-blended into my warmed oils/fats either just before or just after adding the water/lye solution. The amount of powdered goat milk that gets mixed into my fresh milk depends on how much water was mixed in with the lye. I only add enough powder to the fresh milk that would have brought the water amount that was mixed with the lye to an equivalent full concentration of milk according to the powdered GM package directions. In that way, I have used 100% goat milk in place of my entire required water amount without ever having to have gone through the trouble of dissolving my lye directly into the milk, which has always been a pain in the you-know-what for me. The results are a creamy goat milk soap that does not discolor to tan. Win/win!


IrishLass

 

[shunt2011]

I do the exact same as Irishlass. Works wonderful and don’t have to worry about freezing or scorching the milk.

 

[CatahoulaBubble]

I only make cp milk soaps. I use grocery store goat or cows milk and I freeze it in ice cube trays then pop them out into a zip lock bag to keep on hand. When I'm ready for a batch of soap I just measure out the milk in place of water and add my lye to the cubes and stir constantly until the milk is melted and the lye dissolved completely.

Then I set aside my lye mixture while measure and warm my oils. By that time my lye mixture is at about 77°F and I let my oils cool to about 98°F and then I mix the two. If I'm adding only one fragrance oil to my batch I add the FO before the lye but that's just me. If I'm split ting the batch for multiple scents then I add it after light trace.

I've had goat milk soap sitting on my shelf for 3 years and it's never gone rancid. The lye breaks down the fats in the milk and the sugars just add to the lather factor.

 

[TheGecko]

Years ago, I used to use the canned concentrated Meyenberg, which does make for a nice soap, but I switched to using fresh mixed with powdered because I didn't like the tan color that the canned concentrated type always gave to my soaps.

Did you dilute it? I only ask because I use 50/50 and while the lye solution is a very light tan color, my GMS comes out a creamy color with no trace of tan (except for the first batch I failed at). I use 1 tea of Kaolin Clay PPO, but no TD.

 

[IrishLass]

No, I did not dilute the concentrated canned goat milk.


IrishLass

 

[Mobjack Bay]

I love using the split method to make goat milk soap using fresh goat milk and GMP. I made my first batch using frozen GM. Then I read about the split method here. It’s so much easier. I’ve made two more batches using the split method, plus a batch of G[oat] milk soap where I mixed the GMP into oat milk. For the straight goat milk soap, I made the soap as individual bars and stuck them in the frig on a tray to keep them cool. I did the G[oat] milk soap in a loaf mold and it gelled. You can see the color of the resulting soaps, here. I did not use any colorants in either soap, but the G[oat] milk soap has some ground flax.