Photo by Lara Ferroni. I ❤ all of her photos. Swoon.
There are a wide variety of natural ingredients that can be used in cold process soap. From natural colorants and exfoliants to essential oils and extracts, new soapy ingredients are always popping up. Recently, adding fruit and vegetable purees to cold process soap has become extremely popular. Natural purees can add color and skin-loving properties to your bars. In addition, natural purees in bath and beauty products are fantastic from a marketing standpoint. Who doesn’t want a bar of soap made with their favorite fruit or veggie?
In general, there are no limits to what kind of natural purees you can add to soap. In my new book, Pure Soapmaking, there are recipes that include purees of blueberry, cucumber, tomato, aloe leaf, banana and potatoes. Here on the blog, you can find soap made with purees of pumpkin, strawberry, carrots and avocado. If you can blend it into a smooth consistency, you can (most likely) add it to cold process soap.
Adding purees to soap is an advanced technique. If you have never made cold process soap before, I highly recommend getting a few basic batches under your belt before using purees in your soap. It’s important to get an understanding of how soap behaves without additional sugar, water and fats. A solid grasp on how “normal” cold process soap behaves will allow you to alter your techniques and recipe accordingly when you begin to add uncommon ingredients. Remember: soapmaking is a science. Tweaking a recipe with extra ingredients (like purees) alters the chemical reactions between the lye and oils.
Purees add extra sugar, fats and water to your soap. Each type of puree will affect your soap recipe a little differently. The amount of water, fat and sugar will vary depending on the ingredient and how the puree was made. Before adding your puree, it’s important to consider the properties of the fruit and vegetable and how it will affect your batch. For example, a strawberry puree will add extra sugar and water. Using an avocado puree will add extra fats and water, but not much additional sugar. A cucumber puree (shown below) adds mostly water and a very small amount of sugar.
Each puree will add different properties to your soap. For example, cucumber puree (shown above) will add extra water to the soap, but very little sugar. Photo by Lara Ferroni. ❤❤❤.
It’s also important to consider the source of the puree and how it was created. Many soapers choose to make their purees for soaping at home, so they have complete control over the ingredients. If you are purchasing the puree from the store, read the ingredients carefully. Avoid purees with added sugar, thickeners, preservatives, colors or other additives. These extra ingredients can have unpredictable results on your soap. Look for purees that only contain the vegetable or fruit and water.
Most purees can be created by placing them into a blender or food processor until completely smooth. Some ingredients may require a small amount of additional water to achieve a smooth texture. Don’t forget to always use distilled water! If adding extra water to your ingredient to blend into a puree, I highly recommend using a water discount in your recipe. Natural fruits and vegetables contain water. If you’re adding the vegetable/fruit in addition to extra water to make a puree, all that extra water can throw your recipe off balance. Too much water is not dangerous to your recipe. But, it can increase the chances of glycerin rivers, and will increase the time your soap needs to stay in the mold and cure. Read this post to learn how to water discount your recipe, and the benefits of doing so.
In the photo above, I used an avocado puree (avocado + distilled water) along with French green clay and spirulina powder for color. You can find the full tutorial here. I promoted gel phase by insulating, because I wanted the spirulina powder to be nice and bright. You can see it went through a partial gel phase in the center of the soap. Because of the extra water within the avocado puree, the soap also developed glycerin rivers. This soap is totally fine to use and actually looks pretty great! But, it wasn’t the look I was going for. I remade the soap with a steep water discount and placed it in the fridge and it turned out much better.
Once the puree has been prepared, I prefer to add it at thin trace. This makes the purees easy to incorporate with a stick blender or whisk. As a rule of thumb, if the puree contains a lot of sugar (ex: fruits), expect it to speed up trace. If the puree contains little to no sugar (ex: cucumber, avocado, tomato, pumpkin), expect it to thicken trace very slightly, or not at all. When working with a puree for the first time, I like to use a slow moving recipe to be on the safe side. I also prefer a simple design with no complicated swirls when using purees. If attempting a swirled soap with purees, have a backup plan! That way, if the puree speeds up trace you don’t have a ruined batch.
Adding sugar to cold process soap not only speeds up trace, it also increases the temperature. Ingredients such as milk, fruit juices and honey, which contain natural sugars, increase the temperature of soap. To learn more about working with honey in cold process soap, click here. Higher temperatures increase the chance of the soap going through gel phase. ‘Gelling’ and ‘gel phasing’ in cold process soap refers to a part of the saponification (soapmaking) process where the soap gets warm and gelatinous – up to 180 degrees. Click here to read more about gel phase. Gel phase is not harmful to soap. But, soap can volcano when it becomes too hot. If the puree contains a lot of sugar, I recommend soaping at cooler temperatures and placing the soap into the fridge or freezer after pouring into the mold to help it stay cool throughout the saponification process.
Just how much puree to add will depend on personal preference. A safe place to start is 1 ounce per pound of soap. Adding too much puree can throw off the balance of lye and oils. Worst case scenario, adding too much puree could cause mold and bacteria growth in the soap. If you’re worried about this, stick with a lower usage rate.
Now that the soap has been made…what about the shelf life? The pH level of cold process soap does not allow for mold and bacteria to grow. While the oils within the soap can go rancid, mold and bacteria will not grow. If oils go rancid in cold process soap, DOS (dreaded orange spots) can occur. Click here to learn more about DOS and how to avoid it. It’s hard to say exactly how fresh ingredients affect the shelf life of cold process soap, because it will vary greatly depending on the recipe and environment. Like soapmaking oils, fresh ingredients can go rancid within the soap. But, the pH level will not allow it to grow mold and bacteria unless a lot of puree is added.
A great example of this is the Strawberries & Cream Cold Process Soap. As you can see above, the puree started to turn brown in the soap. But, the soap is not growing mold. The pH level of the soap does not allow it to do so. The soap is still safe to use. It just doesn’t look quite as pretty as it did when it was freshly cut. In my experience, fresh purees can cause DOS more quickly in soap as well. I recommend using soap that contains fresh purees within 6 months after curing, just to be on the safe side.
I do not recommend using purees in rebatch soap or melt and pour soap. In cold process soap, the puree goes through the saponification process along with the oils and lye. The harsh pH environment of cold process soap kills the components in the fresh ingredients that could grow mold. If adding purees to melt and pour or rebatch, the puree does not go through the saponification process. Fresh purees will go bad very quickly in melt and pour and rebatch soap, and will most likely grow mold as well.
Looking for some fun puree recipes to get you started? Carrot puree was added to the Buttermilk Bastille Baby Bar on Soap Queen TV. Carrot puree is known for its antioxidant properties and gives the soap a soft yellow-ish orange color. For this recipe, I used baby food but you could certainly use handmade puree. When using purees from the store, just make sure the only ingredients are the vegetable (ex: carrot) and water.
Another popular puree in cold process soap is pumpkin. Pumpkin puree is easy to find at the store, and it behaves well in soap. Depending on how much you use, pumpkin puree gives the soap a very gentle orange color. A great example of this is the Pumpkin Spice Swirl Cold Process Soap. After adding the pumpkin puree to trace, the soap turned a soft orange hue. To help lighten the color, I added a bit of titanium dioxide. This helped the orange color in the swirl really pop. For this recipe, I used a 15% water discount to compensate for the water in the pumpkin puree. Click here to learn how to make your own pumpkin puree.
Phew! I hope this post has helped you grasp working with purees in cold process soap. Like I stated previously, I highly recommend getting a few cold process recipes under your belt first before adding purees to your soap. They affect every stage of the soaping process from recipe development and trace, to temperature and cure time. If interested in more recipes using purees, my book Pure Soapmaking is full of ideas and inspiration.
What is your favorite puree to use in cold process soap? I have a hard time choosing, but I particularly love aloe and pumpkin!