Food emulsifiers are active substances that uniformly form dispersions of two or more immiscible phases (such as oil and water) by physical methods. It occupies a very important position in the food industry, can improve the quality of food, prevent food spoilage, extend the shelf life of food, improve the taste and appearance of food, and stimulate consumer demand.The use of food emulsifier began with adding monoglyceride and lecithin to margarine. Originally, these substances were only known as emulsifiers. However, as studies progressed, more functions were found and they began to be used in various fields, such as bread, ice cream and cake.
food ingredient food emulsifiers function of emulsifiers
Why do bread and tofu need emulsifiers? Generally speaking, an emulsifier is well known for its emulsifying effects, however, actually it has various functions and followings are just some examples:
● Modifies oil crystal and prevents water spattering in cooking.
● Destroys emulsion to stabilize foam and to make smooth texture in ice cream, and keeps its shape.
● Reacts with proteins to make a smooth easy-rising dough in bread.
● Acts on starch to make bread soft.
Oil and water produce emulsion by stirring, however, the emulsion starts to break down immediately after stirring is stopped. The purpose of emulsification is to stabilize emulsion state by preventing break down which occurs due to creaming aggregation and coalescence. To solve these issues, decreasing size of dispersed particles, reducing the density different of dispersion and protecting the surface of oil droplets are effective.
There are two types of emulsion, O/W emulsion or oil droplets in water, which can be found in ice cream and or milk, and W/O emulsion or water droplets in oil, found in butter and margarine.
Recently, developments of W/O/W type emulsion or water dispersed within oil droplets of O/W type emulsion and O/W/O type, an opposite type emulsion have been progressing.
These multiple type emulsions not only make low calorie items such as cream which contain less oil, but also stabilize the emulsion by dissolving the unstable substance present in the deepest region of water droplets. Taste can also be enhanced by injecting seasonings and flavors into the water droplets.
Foaming ability is one of the major characteristics of emulsifiers. When a solution containing an emulsifier is stirred, the emulsifier is adsorbed on the surface of the produced foam to make a mono-molecular layer and the foam outside of the solution makes a bimolecular layer of the emulsifier.
The film coating a bubble is about 100 times thicker than a bimolecular layer, but a bubble breaks off as soon as migration of liquid trapped between bimolecular films occurs.
The addition of emulsifier enables foaming and stabilizes emulsion state of products, thus, smooth texture and expanded volume can be obtained. Typically, emulsifier for ability above is used for cakes, ice cream, moose, whipped topping, etc.
Anti-foaming / Defoaming
Emulsifier also has anti-foaming and defoaming ability. Anti-foaming or defoaming agents are used in food production where undesirable foaming may occur in the presence of protein, starch etc.
Anti-Foaming/Defoaming Agents Characteristics:
• water insoluble
• floatable on the surface because of its small specific gravity
• small surface tension and easy spreading on liquid surface
These characteristics lower the surface tension, and the foam will get thinner. As these agents spread on the liquid surface, all foam will be diminished.
Action on Starch
Fresh bread is soft, but it becomes elastic and hardens over time.Starch particles consist of spherical shaped amylopectine and amylose. Raw starch called beta-starch is insoluble in water.But when heated to a certain temperature, the starch absorbs water and changes into the crystalline form of alpha-starch.Amylose gets hard easily with cooling and amylopectin becomes hard gradually with time. The immediate hardening of bread by cooling is mainly due to the change of amylose.Amylose changes to a helix structure, a kind of spiral structure by heating. If monoglycerides are introduced, they can be anchored into the helix structure. Since the anchoring does not change even after cooling, softness is maintained.This function is also utilized for instant mashed potatoes, noodles and rice.
Action on Protein
Wheat flour contains protein called gluten which takes the shape of a mesh-like structured when mixed with water.This wheat flour and water based dough is filled with carbon dioxide produced by fermentation and steam generated during baking, which produces raised bread.
When the gluten content is small, the dough only rises a little.An emulsifier modifies gluten molecules and enhances its film-forming power resulting in good spreadability and improvement of working efficiency. Thus, easy-rising bread can be obtained.
Food emulsifiers are widely used in the food industry. As a quality improver in bread and cake foods, it can prevent the hydrophobic effect of amylose in the flour, thereby preventing the aging and retrogradation of the dough; promote the formation of gluten tissue, enhance toughness; improve foamability, and make pores dispersed and dense; Promote shortening emulsification, dispersion, improve texture and taste. In margarine, the water can be dispersed into the oil to make a stable and uniform emulsion, thereby improving the structure of the margarine. Emulsify and disperse the added oil in confectionary food, improve the delicateness of the taste, and at the same time make the surface of the product frosted to prevent sticking to the wrapping paper and prevent the crystallization of sugar. In beverages, it can play the roles of aroma, solubilization, emulsifying and dispersing, and anti-oxidation. In ice cream, chocolate and other foods, the size and growth rate of fat crystals can be controlled, and the structure of products can be improved.
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