Mayonnaise is an oil-in-water emulsion typically containing more than 74% vegetable oil (minimum 65%).
In mayonnaise production, egg yolk is used as an emulsifier at a level commonly between 4% and 8%. Water makes up the continuous phase of the formula at 5-15% with various other additives for flavor such as salt, sugar, spices and vinegar or an alternative edible acid (i.e. lemon or lime juice).
Commercial mayonnaise production is often a two-step process. In the first step, oil is coarsely dispersed (i.e. 20-100μm) in a pre-mix tank along with the other required ingredients. The resulting pre-mix is then transferred from the tank in a flowing stream through an emulsifying machine to finely sub-divide the oil into droplets averaging between 1-5μm in size. The sub-division or oil into fine droplets forms a densely packed (i.e. space-filling) structure that creates a high viscosity oil-in-water emulsion. High viscosity is a desirable quality for industrial mayonnaise because it improves the level of stability in the product.
The physical structure formed while mayonnaise processing is largely dependent on the product’s oil volume fraction and droplet size distribution. The densely packed structure of oil droplets determines the consistency and rheological properties of mayonnaise. The smaller the droplets are, the more densely packed the mayonnaise structure becomes, resulting in higher viscosities. So if stiffer mayonnaise is desired, mayonnaise equipment capable of producing smaller oil droplets is necessary.