This document discusses emulsions and foams. It defines emulsions as dispersions of one liquid suspended in tiny droplets within another liquid, and describes two main types - oil-in-water and water-in-oil emulsions. It explains how emulsions are classified based on stability, and discusses common emulsifying agents and techniques used to create emulsions. The document also provides examples of common food emulsions like milk, butter, mayonnaise and salad dressings. Finally, it defines foams as dispersions of gas bubbles in liquid or semisolid phases, and notes two types and some foams used in cooking like beaten eggs and whipped cream.

1. Emulsions
Compiled by:
Dr. Vandana Mahajani

2. Types of Emulsions
• Emulsion is a collidal dispersion of tiny droplets of one liquid
suspended in another.
• Food emulsions are of two types:
• A) Oil in water or O/W , here the droplets of oil are dispersed in
water. e.g milk, mayonnaise.
• B) Water in oil, W/O in which droplest sof water are mixed in oil. Eg.
Margarine and butter.
• Emulsions may be classisied on the basis of stability.
• Temporary emulsions eg. French dressing
• Semi permanent emulsions eg. Milk
• Permanent emulsions eg. Mayonnaise, homogemised milk.

3. Theory of Emulsification
• The main step is to break down the bulk of liquid in tiny droplets
and then stabilize the emulsion.
• There is a tendency of droplets of two liquids to separate out so
emulsifying agents are used.
• Beaters , stirrers, homogenizers etc are used.
• An electric charge furthue stbilizes the emulsions.

4. Some common food emulsions
• Milk and cream: O/W : Phospholipids and protein caseinogen
• Butter and margarine; W/O :caseinogen and GMS
• Egg yolk: O/W: contains Lecithin
• Hollandaise sauce: O/W: Egg Yolk
• Slad dressings: Mayonnaise: O/W egg yolk and GMS
• French Dressing: O/W : do
• Gravies , sauces, soups : O/W water in refined flour.
• Pastry : O/W : egg
• Batters: O/W : flour and egg
• Ice cream: O/W: caseinogen, GMS, alginates, gum, gelatin.

5. Foams
• A foam is a dispersion of gas bubbles in a liquid or semisolid phase.
• Foams are of two types:
• Gas in liquid
• Gas in solid
• Beaten egg with sugar is a gas in liquid dispersion. When it is baked
it becomes a gas in solid dispersion e.g. meringue.
• Foams used in cookery include egg white, egg yolk, gelatin, and
cream. They contribute towards the lightness, volume and texture
of the product.