Food homogenization

Homogenization — followed by emulsification — involves coaxing two otherwise immiscible liquids into mixing to create a new, often creamy, liquid. As a unit operation, homogenization performs multiple functions such as reduction of particle size, dissolution, mixing, dispersion, encapsulation, and emulsification. For example, fat globules in milk are reduced to extremely small particles and distributing it uniformly throughout a fluid, such as milk.

For this reason, the food and beverage industries frequent this technique for manufacture of dairy products, mayonnaise, ice cream, cream liqueurs, salad dressings, and more. Cream and other food products, such as peanut butter, may be homogenized to produce a stable emulsion—one in which fats or oils will not separate from other elements.

A homogenizer consists of a high-pressure pump that forces fat globules through tiny channels, where the globules are significantly size-reduced and uniformly dispersed in the water phase.

The intensive pressure applied by a high-pressure homogenizer causes most foods to attain more stable chemical structures; It help deliver a product with uniform texture, flavoring and taste through a scalable and cost-effective process that allows for a longer period of freshness than food comprised of larger particles.

Homogenization improves shelf life, enhances flavor and mouthfeel, contributes to spoilage prevention (without denaturing desirable enzymes and other proteins), and helps prevent the unappealing separation of layers that can occur improperly emulsified foods.
Food homogenization

Emulsification process

An emulsion is a mixture of two immiscible liquid phases where one phase is dispersed into another and emulsification is preparation of such a dispersion. An emulsion is a thermodynamically unstable system.

Emulsification is a “process” of making a metastable mixture like water and oil, which eventually separates into two phases in equilibrium.

A number of the emulsion systems are found in nature and human bodies; bile acid acts as an emulsifier to help digestion and absorption of fat by the formation of finely dispersed emulsion droplets, and lipoprotein forms an emulsion to deliver and metabolize fat in the body.

Emulsions are found in different industries such as food, pharmaceutical, agricultural, cosmetics, and petroleum. An emulsion is not contained only water and oil; it may also contain some solid particles and even gas.

A surfactant is a chemical substance that alters interfacial properties by absorbing to the boundary between two immiscible phases. The chemical structure of surfactant consists of hydrophilic and lipophilic groups. The lipophilic group of surfactant molecule tends to move away from the water molecules by so-called “hydrophobic interaction.”

Essentially, there are three types of emulsions which are:
*Water-in-oil (W/O),
*Oil-in-water (O/W), and
*Complex emulsions such as water-in-oil-in-water (W/O/W). The complex emulsion also known as a multiple emulsion

Other types of emulsions
*Microemulsions: Microemulsions are systems consisting of water, oil and surfactant, which constitute a single optically isotropic and thermodynamically stable liquid solution.
*Pickering emulsion: The solid particles in the colloidal size may be used as emulsion stabilizers. Such particles are known as pickering emulsion. Pickering emulsions are recently employed in many areas like cosmetics, food, pharmaceuticals, oil recovery and waste water treatment.

Three theories of emulsion:
*Surface Tension Theory: by lowering of interfacial tension
*Oriented Wedge Theory: mono molecular layers of emulsifying agents are curved around a droplet of the internal phase of the emulsion
*Interfacial Film theory: A film of emulsifying agent prevents the contact and coalescing of the dispersed phase
Emulsification process