This article mainly introduces the classification and application of natural surfactants. Visit https://www.alfa-chemistry.com/products/surfactant-124.htm for more information.

1. Classification and Application of
Natural Surfactants

2. Introduction
• Natural surfactants are widely used in daily life and science. Most of
the natural surfactants come from animal and plant organisms, and
are relatively complex high molecular organic substances. Because of
their high hydrophilicity, they can form emulsions. Most natural
surfactants have high viscosity and emulsion stability and are widely
used in medicine, food, cosmetics and detergents. Common natural
surfactants include lecithin, cholesterol, lanolin, tea saponin, protein,
saponins, sugars and alkyl polyglycosides. Most of the natural
surfactants are non-irritating, non-toxic and side effects, easy to be
biodegraded, and have good compatibility. Therefore, they are the
development direction of future surfactants.

3. Lecithin
• Lecithin is present in biological cells such as the eggs, brain and other
tissues of animals as well as in plant seeds or germs. Lecithin has an
amphiphilic structure. And it has excellent physiological activities such
as emulsifying, dispersing and anti-oxidation, and is an excellent
natural surfactant and an important emulsifier. When dispersed in
water, lecithin can form a phospholipid small cell body (fat body)
having a stable bimolecular membrane structure. This fat body can be
used as a carrier for medicines, and can also be widely used in skin
care, hair care and makeup products. Lecithin can also be involved in
the metabolism of cells, with the function of activating cells and anti-
aging.

4. Cholesterol
• Cholesterol is a natural emulsifier found in animal brain and nervous
tissues as well as lanolin and egg yolk. The molecular structure of
cholesterol has a strong hydrophobicity and is therefore suitable for
the preparation of oil-soluble emulsifiers. The sebum secretion in the
skin is rich in cholesterol and its derivatives, which have the functions
of skin care and hair care. Cholesterol is also a co-emulsifier that
promotes and enhances the function of other surfactants. It can be
applied to cosmetic preparations to help stabilize pigments and
lotions.

5. Lanolin
• Lanolin is the secretion of the sebaceous glands of sheep, mostly
extracted from wool. The emulsion prepared from lanolin and its
derivatives is easy to absorb by the skin, has good stability and good
emollient properties, so it is mostly used in creams and oily emulsions.
Isopropyl lanolinate has a strong hydrophilic action and can be used
in cream preparations. Lanolin alcohol has strong water/oil
emulsification properties and also stabilizes oil/water emulsions.
Hydrogenated lanolin is a water/oil emulsifier and an oil/water
emulsion stabilizer. It has strong water absorption and is easily
absorbed by the skin. Lanolin acid soap contains potassium ion,
sodium ion, triethanolamine, etc., and has an emulsification effect.

6. Tea saponin
• Tea saponin is an extract of tea, a triterpenoid saponin with strong
surface activity and resistance to hard water. Tea saponin has many
functions such as emulsification, decontamination, wetting,
dispersion, and foaming. Different "oil phase" emulsifiers can be
developed using the emulsification properties of tea saponin.
Washing the wool fabric with tea saponin maintains the fabric in a
vibrant color. Tea saponin has the functions of hair care, anti-dandruff
and anti-hair loss, so it is often used in shampoos. Tea saponin is an
excellent natural surfactant with an emulsifying ability exceeding that
of oleic acid soap, alkyl sulfonate and polyoxyethylene fatty alcohol
ether.

7. Protein
• The protein is composed of amino acids, containing both a hydrophilic
group and a hydrophobic group, and is a polymeric surfactant. Protein
is an essential nutrient for the body and is often used as a food
emulsifier. There are many kinds of proteins, such as milk protein, egg
protein, casein, soy protein, etc., which have the functions of
emulsification, foaming and colloid protection. The functions and
applications of different varieties of proteins are also different. Mucin
is a glycoprotein that binds water molecules and stabilizes the
emulsion. It can be used as a co-emulsifier in skin care products. The
yolk high-phosphorus protein is extracted from egg yolk, is easily
soluble in water, has remarkable surface ability and stable emulsion
performance, and is an excellent nutrient and emulsifier for skin care
products.

8. Phytosterol
• The phytosterol can be extracted from soybean oil and composed of
sitosterol, stigmasterol, campesterol, VE and the like. It has similar
physicochemical properties to cholesterol, has a weak surface activity,
and also has antibacterial, anti-inflammatory and hair care effects. It
should be particularly noted that phytosterols have a liquid crystal
structure and are often used to prepare liposomes.

9. Alkyl glycoside
• Alkyl glycosides are synthesized from sugars. Alkyl glycosides have
weak skin irritation, broad-spectrum antibacterial properties, and
good compatibility with other types of surfactants. The alkyl glycoside
has excellent wetting and foaming properties and has obvious
thickening effect, so it has a wide range of applications. Adding alkyl
glycosides to the washing powder can improve the detergency of the
washing powder. The use of an alkyl glycoside in a meal lotion can
improve the solubility and mildness of the preparation and reduce
the degreasing power to the skin.

10. Saponin
• The saponin is composed of a sapogenin and a sugar, and the sugar
which can constitute the saponin includes glucose, galactose,
rhamnose, arabinose, glucuronic acid, galacturonic acid and the like.
According to different structures, sapogenin can be divided into
triterpenoid saponins and steroidal saponins, wherein the distribution
of triterpenoid saponins is more extensive and more diverse than
steroidal saponins. There are many plants containing saponins, which
are common in Liliaceae, Dioscoreae, Agave, Rosaceae, Dianthus,
Polygonaceae, Araliaceae, Cucurbitaceae, etc. Most of these plants
have descaling and emulsifying functions and are important natural
surfactants.

11. Carbohydrate
• The natural degrading power of carbohydrate natural surfactants is
weak, but most of them have thickening, emulsifying and stabilizing
effects. Carrageenan is a widely used co-emulsifier. It has a stabilizing
effect on colloids (such as toothpaste and shaving cream). It also has
a film-forming function and can be applied to hair gel. Alginic acid and
its sodium salt are commonly used thickeners and emulsifiers, have a
moisturizing effect and can be used in shampoos. Pullulan has an
emulsification function and is commonly used in cleansing cosmetics
to have a moisturizing function. Cyclodextrins are oligosaccharides
composed of glucose units and have a cyclic structure. It has surface
activity such as emulsification, solubilization and dispersion, and can
be used in essential oils and flavors.

12. Fatty acid monoglyceride
• The chemical formula of fatty acid monoglyceride is
C17H33COOCH2CHOHCH2OH, which is a creamy waxy solid with a
melting point of 56 ℃. It can be dispersed in hot water and dissolved
in ethanol. It is a lipophilic surfactant. Fatty acid monoglycerides are
versatile emulsifiers. Because it can be completely biodegraded into
glycerin and fatty acids, non-toxic and highly safe, it is recognized as
an environmentally friendly "green" product and is widely used as an
emulsifier for foods and cosmetics.