What are the applications of surfactants in food?

Surfactants are molecules containing fixed hydrophilic and lipophilic groups, which can be concentrated on the surface of the solution, the interface of two immiscible solutions or the interface of liquids and solids, to reduce their surface tension or interfacial tension of a large class of compounds.
Surfactants are widely used in the food industry. Adding surfactants to some food products can greatly improve the processing conditions, improve product quality and prolong the freshness of food. High-quality food processing is inseparable from the application of surfactants.
Introduction of surfactants
Any substance that can significantly change the surface (or interface) state of a system is called a surfactant. Surfactants can greatly reduce the surface (or interfacial) tension of the system, so that the system can produce wetting and counter-wetting, emulsification and demulsification, dispersion and cohesion, foaming and antifoaming, solubilization, and a series of effects. Therefore, in the food industry, surfactants can be used as emulsifiers, dispersants, wetting agents, defoamers, viscosity regulators, fungicides and so on.
Types of surfactants for food
The use of surfactants in the food industry is strictly limited and cannot be harmful to human body.
The surfactants approved by the Food and Agriculture Organization of the United Nations and the World Health Organization (FAO/WHO) are: glycerol fatty acid esters, sucrose fatty acid esters, soybean phospholipids, acetic acid and tartaric acid mono- and diglycerides, diacetyl tartaric acid mono- and diglycerides, citrate, polyglycerol fatty acid and ricinoleic acid ester, stearoyl citrate and tartaric acid ester, stearoyl lactylate, calcium (sodium), stearoyl fumarate, sorbic Fatty acid esters of alcohol anhydride, polyoxyethylene (20) and (40) stearates, etc. Polymeric surfactants such as sodium alginate, sodium pectate, carrageenan, chitosan water-soluble protein, etc. Most of them are semi-synthetic polyalcoholic nonionic surfactants, of which soybean phospholipids and some polymeric surfactants are natural.
The main role of surfactants in food
1. Avoid active agents as emulsifiers emulsifiers usually have hydrophilic (hydroxyl, etc.) and lipophilic (alkyl) molecules, easy to form an adsorption layer on the interface between water and oil, is a surfactant, which can be divided into water-in-oil and water-in-oil two types.
The total number of available emulsifiers is about 65, commonly used fatty acid glycerides (mainly monoglyceride), fatty acid sucrose esters, fatty acid sorbitan anhydride esters, fatty acid propylene glycol esters, soybean phospholipids, gum arabic, alginic acid, sodium caseinate, gelatin and egg yolk and so on.
Emulsifiers can improve the surface tension between the various components of the emulsion, so that the formation of a uniform dispersion or emulsion, thereby improving the structure of the food organization taste and appearance, improve food preservation.
Surfactants as emulsifiers play an extremely important role in the food industry, providing good conditions for the development of the food industry, and it can be said that emulsifiers are indispensable for all walks of life in food processing. The following is a brief description of the main role of emulsifiers used in various processed foods.
Bread and eggs: to prevent the hydrophobic effect of wheat flour in the straight chain starch, thus preventing the aging back to life, reduce the viscosity of the dough to facilitate the operation, promote the formation of gluten tissue, improve the foaming properties, and make the air holes dispersed dense, and promote the emulsification of shortening dispersion, thus improving the organization and texture.
For example, adding 0.2%~0.3% of flour amount of monoglycerides in bread can effectively prevent aging and make the flour become soft. Adding 0.2%~0.5% of sucrose ester (HLB11 or above) can improve the foaming effect, and wetting, so that the texture of bread and cake is softer.
2 surfactant as a thickener thickener is able to improve the viscosity of food or the formation of a class of gel additives, with the role of stabilizing the emulsification or suspension, is a hydrophilic polymer compounds, generally known as polymer surfactants, also known as viscosity regulators, gelling agents and emulsion stabilizers and so on. The total number of nearly 40 kinds, divided into natural and chemical synthesis of two categories.
Most of the natural thickening agent from the mucilage containing polysaccharides of plants and algae, such as starch, gum arabic, guar gum, carrageenan gum, pectin, agar and alginate and so on.
Also from protein-containing plants and animals, such as gelatin, casein and sodium kojic acid. There are also produced from microorganisms, such as Hansen’s gum (xanthan gum) and so on. Synthetic thickeners, such as sodium carboxymethyl cellulose CMC, propylene glycol acid alginate, cellulose glycolic acid and sodium polyacrylate, sodium starch glycolate, sodium starch phosphate, methyl cellulose and sodium polyacrylate.
Polymer surfactants generally have the following characteristics: small ability to reduce interfacial tension, most do not form strand bundles, weak penetration, poor foaming power, but the formation of a stable foam emulsification, dispersion and cohesion is excellent. They are mostly used in sauces, jams, ice creams, canned foods, candies and quick-cooking noodles. For example, sodium carboxymethyl cellulose, with viscosity, stability, film formation and other characteristics, and thus used in ice cream can improve water retention and organizational structure, can be used as a foam stabilizer for beer, but also used in jams, cream, peanut white off and so on can be improved applicability. It can be used for cookies and other diet food because it is not easy to be digested due to its strong expansion after absorbing water.
3. Surfactants in food production in the special application of surfactants in food production in addition to emulsifiers/thickeners, can also be used as a dispersant, wetting agent, foaming agent, defoamer, crystallization control agents, fungicides, and so on, and to extend the freshness period of the role of food.

Surfactants as dispersants and wetting agents can improve the hydrophilicity and dispersion of milk powder, cocoa powder and other powdered foods. Whole milk powder granulation by adding 0.2% to 0.3% of soybean phospholipids, when brewing can be quickly dissolved without agglomeration.
It has been reported that manufactured products with a phospholipid content of about 0.35%~0.5% by weight can be wetted and dispersed in 6°C water in less than 10 min, and their wettability can remain stable for more than one year at room temperature. The wetting agent does not bring bad taste or odor to the rehydrated beverage. Cocoa powder particles are fine and covered with an oily film, which is difficult to be dispersed, and its dispersing ability can be improved with sucrose ester.
In the production of pastry, ice cream, etc., the addition of glycerol monohydrate can improve the degree of fat dispersion, produce a fine pore-shaped structure, and improve the quality of food.