The Roles of Different Fats and Oils in Soap Making
Fats and Oils in Soap Making
- What is saponification
- Estimation of saponification of fats and oils
- Saturated fats
- Butters and additive fats
- Cocoa butter
- Shea butter
What Is Saponification?
Saponification is a type of chemical reaction between a strong alkali or base (such as sodium or potassium hydroxide) and a fat. Animal and vegetable fats and oils are made of ester molecules called triglycerides. An ester is a molecule that is formed from an alcohol and an acid. In the case of fats, glycerin is the alcohol, and the acids are fatty acids like stearic, oleic, and palmitic acids.
When the alkali solution is thoroughly mixed with the oils, a reaction called saponification begins. What this means is that the glyceride of the triglyceride breaks off to form glycerine and the sodium or potassium bond with the fatty acid to form soap. With sodium, you get bar soap; with potassium, you get liquid soap.
Every oil or fat has what is called a saponification number, which is determined by the amount of alkali needed to completely saponify the fat. This number is determined by titration a test sample with a standardized alkali and acid/base indicator.
Estimation of Saponification of Fats and Oils
Most people have heard about saturated fats and their link to obesity and heart disease and other ailments. But for soap, saturated fats have multiple benefit. Saturated fats are usually solid at room temperature and consist of straight-chained molecules.
For bar soap, they give the soap hardness as helping the soap last longer in the shower. Most commonly used saturated fat used for commercial soap making is beef fat, also known as tallow. It is usually the first and most abundant ingredient in many soaps. It is widely available as a by-product from the meat industry and is therefore one of the cheapest fats. It created a white and very hard bar of soap. Many people with sensitive skin have problems with soaps made with beef tallow. So, they usually use body washes or seek out bar soap made from gentler vegetable sources
Another common saturated fat is coconut oil. It also gives a very hard white bar of soap, but unlike tallow, the fatty acids are shorter length carbon chains that increase water solubility. This greater solubility in water helps generate more suds and increases the cleaning ability. Unfortunately, soap made from coconut oil alone would be drying to the skin so some conditioning and moisturizing ingredients need to be added. This drying of the skin is testament to the cleaning power of coconut fatty acid soaps. Alone they strip the skins natural oils right off. Another very common saturated fat is palm oil. It is the go-to replacement for beef tallow for truly vegan soaps. It is also a good fat when skin sensitivity to beef tallow is an issue. A common recipe for homemade vegan soap consist of palm, coconut, and olive oil.
Unsaturated Fats (Liquid Oils)
The best ingredients to balance the saturated fats in a soap recipe are the unsaturated fats. By contrast, these are usually vegetable oils that are liquid at room temperature and consist mainly of bent and branched chain molecules. They have the property of acting as emollients or moisturizers in soap recipes. In the right proportions, they can effectively offset the drying qualities of saturated fats and create a bar soap that is hard, white, sudsy, and conditioning as well. One of the best condition oils is olive oil. It consists mainly of oleic acid, but the conditioning action mostly comes from the unsaponifiable, which are organic ingredients in the oil that are not acted upon by the alkali. One of which is squalane, which is used in many high-end antiaging cremes. Some other common vegetable oils are soybean, corn oil, safflower oil, castor oil, and sunflower oil. It should be noted that some vegetable oils, notably the polyunsaturated ones, have a shelf life and will darken and go rancid with age.
Butters, Additive Oils, Fats
If a more luxurious soap is desired, you can add special kinds of butters and fast to soap. They add to the smoothness and skin-conditioning properties by leaving a protective barrier on the skin to help moisturize without feeling greasy. Some butters like cocoa butter even have mild pleasant aromas that can add to the bathing experience.
You might already be familiar with cocoa butter in moisturizing creams, cosmetics, and lip balms. It imparts a silky smoothness to personal care products and is an excellent emollient. It's also one of the most stable fats at least partly due to the antioxidants present. It has a typical shelf life of two to five years.
Cocoa butter is extracted from the cocoa bean in tropical regions. It consists of roughly 60% saturated fats and 40% unsaturated fats. It is an offwhite to cream-colored solid which have a melting range of 93 to 101 degrees Fahrenheit, which is near body temperature. But, cocoa butter is stable and quite solid at room temperature. This makes cocoa butter perfect for its most common use of all: the manufacturing of chocolate products. All chocolates are made with cocoa butter including milk chocolate, white chocolate, and dark chocolate.
is a buttery fat extracted from the African shea nut. It is a cream-colored fat this is softer than cocoa butter and does not have as much saturated fat. In its native land of Africa, it is used in food preparation. In fact, it is sometimes combined with other fats to substitute for the more expensive cocoa butter in chocolates. But the taste is different so 100% cocoa butter is the preferred fat for chocolate manufacture. Shea butter
Shea butter also has the property of containing nonsaponifiable components. What this means is shea butter has ingredients that will not chemically interact with alkalies to form soaps. This gives shea butter its texture and emollient capabilities. The main fatty acids are the saturated stearic acid and the unsaturated oleic acid.
Questions & Answers
What is the main difference between soaps made from animal fats and plant oils?
Animal fats typically create a harder bar of soap that may or may not be beneficial to your skin. Vegetable oils produce soap that is generally softer and gentler to the skin. There are exemptions of course. Coconut and Palm Kernel Oils produce soap that is hard and can be drying to the skin. These oils are made of short chain saturated fats that make excellent sudsy cleansing soap. So much so as they strip the skins natural oils. Therefore, most soap recipes don’t have more than 30% coconut or palm kernel oils.Helpful 12
How can I find a chart that not only lists the benefit of soaping oils, but also skin conditions that are improved by certain ingredients? For example, Eczema is improved by using _____oils in CP soap or Extreme dry skin is improved by using _____oils in CP soap.... and so on.
I am not sure on the Eczema aspect but dry skin can be assisted by adding Shea butter or jojoba oils to soap recipe. Also, adding an additional amount of vegetable glycerin would act as an emollient and help trap moisture in.Helpful 8
The saponification reaction occurs between an acid and base, shown in the figure in the procedure. In the reaction performed what is the acid and base?
The “acid” is fatty acid from the oil. It is liberated from the glycerin Ester by the base in saponification. The base is a strong alkali like sodium hydroxide or potassium hydroxide. The saponification byproduct is glycerin from the oil. For soap making, glycerin is not removed from the soap mixture.Helpful 6
There are many "blended" oils on grocery shelves now. Is there an SAP value for blended oils? Ex: 80/20% sunflower & virgin olive oil. Could blended oils be used for soap?
Yes, you can. For example, you can take the 80/20% sunflower & virgin olive oil measure a mass, and use percentage to calculate the masses of each oil. Look up SAP values for each oil and add them together to get the amount of sodium hydroxide or potassium hydroxide required for saponification.Helpful 5