Homogenization or homogenisation is any of several processes used to make a

mixture In chemistry, a mixture is a material made up of two or more different chemical substances which can be separated by physical method. It is an impure substance made up of 2 or more elements or compounds mechanically mixed together in any proporti ...

of two mutually non-soluble liquids the same throughout. This is achieved by turning one of the liquids into a state consisting of extremely small particles distributed uniformly throughout the other liquid. A typical example is the homogenization of

milk Milk is a white liquid food produced by the mammary glands of lactating mammals. It is the primary source of nutrition for young mammals (including breastfeeding, breastfed human infants) before they are able to digestion, digest solid food. ...

, wherein the milk fat globules are reduced in size and dispersed uniformly through the rest of the milk.

Definition

Homogenization (from ''homogeneous'';

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

, : '','' + '','' ) is the process of converting two

immiscible Miscibility () is the property of two chemical substance, substances to mix in all mixing ratio, proportions (that is, to fully dissolution (chemistry), dissolve in each other at any concentration), forming a homogeneity and heterogeneity, homoge ...

liquids (i.e. liquids that are not soluble, in all proportions, one in another) into an

emulsion An emulsion is a mixture of two or more liquids that are normally Miscibility, immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloi ...

, a mixture of two or more liquids that are generally immiscible. Sometimes two types of homogenization are distinguished: primary homogenization, when the emulsion is created directly from separate liquids; and secondary homogenization, when the emulsion is created by the reduction in size of droplets in an existing emulsion. Homogenization is achieved by a mechanical device called a ''

homogenizer A homogenizer is a laboratory or industrial device used to break down and evenly distribute particles within a liquid mixture, creating a stable and uniform emulsion, suspension, or solution. Homogenization (chemistry), Homogenization is a key pro ...

''.

Application

One of the oldest applications of homogenization is in

processing. It is normally preceded by standardization (the mixing of milk from several different

herd A herd is a social group of certain animals of the same species, either wild or domestic. The form of collective animal behavior associated with this is called '' herding''. These animals are known as gregarious animals. The term ''herd'' ...

s or

dairies A dairy is a place where milk is stored and where butter, cheese, and other dairy products are made, or a place where those products are sold. It may be a room, a building, or a larger establishment. In the United States, the word may also des ...

to produce a more consistent

raw milk Raw milk or unpasteurized milk is milk that has not undergone pasteurization, a process of heating liquid foods to kill pathogens for safe consumption and extension of shelf life. Proponents of raw milk have alleged numerous purported benefits t ...

prior to processing). The fat in milk normally separates from the water and collects at the top. Homogenization breaks the fat into smaller sizes so it no longer separates, allowing the sale of non-separating milk at any fat specification.

Methods

High-pressure homogenization

In high-pressure homogenization, a liquid product is forced through a narrow orifice under pressures typically ranging from 1,500 to 35,000 psi. This process reduces particle and droplet size through a combination of shear, turbulence, and cavitation. It is commonly used in the dairy industry to homogenize

, producing uniform fat distribution and improving product stability. High-pressure homogenization is also applied in other beverage categories, such as soft drinks and vegetable-based drinks, to prevent the separation of components during storage. Ultra-high-pressure homogenization (UHPH) systems have been developed to further enhance microbiological stability and shelf life.

High-shear homogenization

High-shear homogenization uses a rotor/stator mechanism to apply intense mechanical shear to a product, promoting dispersion and droplet size reduction. This method is widely used in industries such as food, pharmaceuticals, and cosmetics. Rotor/stator mixers typically achieve droplet sizes in the range of 2–5 microns, with finer distributions possible depending on formulation and processing conditions. A key advantage of high-shear homogenization is that it can improve emulsion uniformity and stability without altering formulation components. This is especially important for commercial products with fixed or regulated ingredient profiles. In a 2016 study, applying high-shear homogenization at 3600 rpm significantly reduced droplet size, improved viscosity, and eliminated phase separation in oil-in-water emulsions, all while maintaining the original formula.

References