Unsaponifiables are compounds found in natural fats and oils that do not form soap when exposed to an alkali solution. They remain as a distinct, non-saponifiable fraction, contributing valuable properties to the oil’s composition. This minor portion is present in varying amounts across different natural sources.
The Saponification Process
Saponification is the chemical reaction that creates soap from fats and oils. It involves triglycerides, the primary components of fats and oils, interacting with a strong base like sodium hydroxide or potassium hydroxide (lye). During this reaction, ester bonds within the triglyceride molecules break down.
This interaction forms glycerol and fatty acid salts, which are soap. The type of alkali used influences the soap’s consistency; for instance, sodium hydroxide yields a harder soap, while potassium hydroxide results in a softer variety. This transformation neutralizes the fats and alkali, yielding a new, stable compound.
Composition of Unsaponifiables
The unsaponifiable fraction of fats and oils is a complex mixture of bioactive compounds that do not convert into soap during saponification. These components are valued for their unique properties.
Sterols
Sterols are a prominent group within unsaponifiables, with phytosterols being significant in plant-derived oils. Beta-sitosterol is a common example, known for its structural similarity to cholesterol. These compounds can help lower low-density lipoprotein (LDL) cholesterol by blocking its absorption.
Vitamins
Fat-soluble vitamins are also found in the unsaponifiable fraction, providing antioxidant and nutritive benefits. Vitamin E, primarily composed of tocopherols, is a powerful antioxidant that helps protect cells from oxidative damage. Precursors to Vitamin A, such as carotenoids, are another group of unsaponifiable compounds that the body can convert into Vitamin A.
Hydrocarbons
Squalene is a notable hydrocarbon in many natural oils, including olive oil. It is a natural component of human sebum, the oily substance produced by our skin. Squalene acts as an excellent emollient and moisturizer, helping maintain skin hydration and suppleness. It also offers antioxidant protection, safeguarding skin surfaces from oxidative damage caused by UV light.
Triterpene Alcohols
Triterpene alcohols represent another class of beneficial compounds found in unsaponifiable matter. They are recognized for their soothing and protective properties, often contributing to anti-inflammatory and antioxidant effects in certain plant extracts. These compounds support skin health and integrity, aiding in healing and restoration.
Natural Sources
Unsaponifiables are present in various natural oils and fats, though their concentration can differ significantly. These compounds are a minor fraction of the total oil but contribute disproportionately to its beneficial properties.
Shea butter is renowned for its high unsaponifiable content, typically ranging from 5% to 11%. This rich composition makes shea butter prized in cosmetic formulations. Avocado oil also contains a notable percentage of unsaponifiables, often between 1.5% and 10%.
Olive oil generally has a lower but significant unsaponifiable content, usually around 0.5% to 3%. Soybean oil, a widely used vegetable oil, typically contains an even smaller percentage, often less than 1%. A higher percentage of unsaponifiables in an oil is generally considered more valuable for applications where their specific bioactive properties are desired.
Applications in Health and Cosmetics
The unique properties of unsaponifiables make them sought after in cosmetics and health supplements. Their stability and beneficial biological activities deliver advantages in various products.
In cosmetics, unsaponifiables function as effective emollients and moisturizers. They strengthen the skin barrier, reducing moisture loss and maintaining skin hydration. Components like squalene and phytosterols soothe irritated skin and provide antioxidant protection against environmental stressors, making them common ingredients in creams, lotions, and balms.
Beyond topical applications, unsaponifiables are utilized in health supplements. Avocado Soybean Unsaponifiables (ASU) is a well-known example, derived from a concentrated extract of avocado and soybean oils. ASU is commonly used as a dietary supplement to support joint health and manage symptoms associated with osteoarthritis. It reduces pain and stiffness while improving joint function, potentially decreasing the need for analgesics. ASU possesses chondroprotective, anabolic, and anticatabolic properties, meaning it can inhibit cartilage breakdown and promote its repair.