INTRODUCTION
Emulsifying agents are substances that are soluble in both fat and water and enable fat to be uniformly dispersed in water as an emulsion. Foods that consist of such emulsion include butter, margarine, salad dressings, mayonnaise, and ice cream. Emulsifying agents are also used in baking to add the smooth incorporation of fat into the dough and to keep the crump soft. Emulsifying agents used in foods include agar, albumin, alginates, casein, egg yolk, glycerol monostearate, gums, Irish moss, lecithin etc.
Emulsifier:
An emulsifier is a molecule in which one end likes to be in an oily environment and the other in a water environment.
Emulsion:
An emulsion is a dispersion (droplets) of one liquid in another immiscible liquid.
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Kurt and Zorba (2009) reported that ph has an effect on the emulsifying properties of egg yolk proteins. The emulsion capacity (EC) increased with increased ph and the optimum ph values were between 4.61 and 7.43. Examples of food emulsions with different ph values are béarnaise and mayonnaise that are made at ph 7 and ph 4 respectively (Anton and Gandemer, 1999).
Egg yolk is said to be a flexible emulsifier since it can stabilize emulsions that are both cold and warm (e.g. Mayonnaise and hollandaise sauce) (American Egg Board, 2013).
3Egg yolk proteins are good emulsifiers since they contain LDL and HDL proteins (American Egg Board, 2013). These proteins are not found in soy and pea protein and therefore one may expect that legume proteins do not have the same emulsifying properties as egg proteins, or that their emulsifying properties will be poor. This literature study showed, nevertheless, that both soy and pea protein possess good emulsifying properties. This denotes that both soy and pea proteins contain surface active molecules, that are amphiphilic, and that they are able to homogenize the two immiscible liquids in the