Fresh ingredients, such as strawberries, avocados, cucumber etc., are a great additive to soap as they contain many skin-beneficial anti-oxidants, vitamins and minerals, plus they are a natural way to add colour and texture to your soap. In addition, fresh produce also adds appeal from a marketing standpoint. Using natural and organic ingredients entices customers who are eco-conscious to buy your soap.
In cold process and hot process soap making, fresh ingredients can be added because the high pH environment of the saponification process will preserve the fresh ingredient and prevent bacteria and mould from growing. However, anything fresh added to your soap must be in liquid form or pureed to a smooth paste, as large chunks or lumps of fresh ingredient are too large to be preserved during the process and will form a breeding ground for moulds and bacteria. For the same reason, methods that don’t involve a saponification process, such as using melt and pour soap bases or rebatching, are also unsuitable for adding fresh ingredients.
Adding fresh ingredients to your soap, can also affect the colour of the soap over time, and some soaps can discolour to a brown or beige after an extended period. The brownish colour is not mould, but simply due to oxidation of the fresh ingredient contained within the soap. Oxidation within soaps can affect colour but can also lead to rancidity of oils, and soaps containing fresh ingredients have a shortened lifespan compared to ‘normal’ soaps, depending on the type and amount of ingredient added. I usually suggest to use such soaps within a year of making to be on the safe side.
When you add a fresh ingredient to your soap, you are also adding additional sugar, fat and water in varying amounts, depending on the ingredient. For example, adding strawberries would add sugar and water to your recipe, whereas cucumber would add mostly water, and avocado would add fat and little water, but nearly no sugar. Because these additions change the formulation of the soap, adding fresh ingredients is considered an advanced technique. If you are a beginner, I suggest to make a few batches first to see how ‘normal’ soap behaves, before you start altering and tweaking recipes. Remember soap making is a science. If you alter the recipe, you will alter the chemical reaction between the lye and the oils. Each additional ingredient will have an impact on this chemical reaction and you need to consider how the ingredient will alter the saponification process and the properties of the soap, and how this will impact the design or soap technique you are planning on using. Adding sugar to the soap will speed up trace and increase temperature during the saponification process. This will make it likely unsuitable for delicate colour work. Adding a fat-containing ingredient, such as avocado, increases the fat content of the formula, which will affect the super-fatting ratio of your soap. This can have an impact if you are already using a high SFR, leaving too much oils unsaponified, which can lead to DOS (dreaded orange spots) and rancidity of the oils. On the other hand, if you have an ingredient that contains a lot of water, such as cucumber, it will increase the overall water content of the formula. Too much water in your soap can make your soap soft and lead to longer curing times, but the extra liquid can also create glycerine rivers in your soap, a mostly aesthetic issue, which doesn’t affect the soap itself, but makes the soap less ‘pretty’. In general, always calculate the extra ingredients into your formula and add a water discount in your lye water. I use a water discount of one to one. So if I add a tablespoon of fresh ingredient, I will use 15 ml less water in my soap recipe. And lastly, use fresh ingredients that your prepare (=puree) yourself. Store-bought pureed products often contain extra (unwanted) additives, such as thickeners, sugar and preservatives.
How to add fresh ingredients to your soap
First, consider the properties of the ingredient and how it will affect the soap and process, and tweak the recipe accordingly. Calculate your water discount and then prepare your fresh ingredient.
All fresh ingredients must be blended to a smooth puree. You can use a Magic Bullet, blender or food processor to blitz it. If you are using a ‘hard’ ingredient, like carrot or pumpkin, I like to cook it in the microwave first, until softened. Sometimes a little extra water or oil is needed to achieve a smooth texture, so don’t forget to calculate the extra water into your formula. You can also juice your ingredient, and use the juice instead, but don’t exchange it or add it to your lye water, especially if your ingredient contains sugar, since this will heat the lye water to a temperature which will literally burn the sugar.
Once you have your puree or juice, you add it to your soap mixture at thin trace. I usually start with 1 tablespoon of puree in 500 g of soap mixture and will go up to 2 tablespoons but no more. Too much fresh ingredient can disrupt to chemical process and prevent proper saponification, but it can also increase the likelihood of mould and bacteria growing. Then using a stick blender, keep pulsing until the puree has been mixed in thoroughly. Remember, that the fresh ingredient will likely increase trace and cause your soap to thicken, so you will need to work quickly after adding. Finish the soap according to your recipe and design, and leave the soap to cure as usual. Because of the fresh ingredient, the soap may need a few extra days before it is ready to be unmolded and cut into bars. And lastly, experiment! There are so many fresh and undiscovered ingredients to use in soaps. Make a test batch, the small square soap molds from Pure Nature are ideal for this, and see what happens! Before you know it, you’ll have discovered the next trend in soap making!