With the improvement of people's living standards, people have higher and higher requirements for food. In addition to satisfying the most basic nutritional value, food should also have good color and fragrance. Therefore, more and more food additives are used in the food industry, and surfactants are the most common type of food additives.
Surfactant is a molecule that contains fixed hydrophilic and lipophilic groups, which can concentrate on the surface of the solution, the interface of two immiscible solutions, or the interface between liquid and solid, which reduces its surface tension or interfacial tension. Class compound. Surfactants are widely used in the food industry. Adding surfactants to some food preparations can greatly improve processing conditions, improve product quality, and extend food preservation periods. High-quality food processing is inseparable from the application of surfactants.
Introduction to Surfactants
Any substance that can significantly change the surface (or interface) state of the system is called a surfactant. Surfactants can greatly reduce the surface (or interfacial) tension of the system, and make the system produce a series of effects such as wetting and de-wetting, emulsification and demulsification, dispersion and aggregation, foaming and defoaming, and solubilization. Therefore, in the food industry, surfactants can be used as emulsifiers, dispersants, wetting agents, defoamers, viscosity regulators, bactericides, etc.
Types of food surfactants
The use of surfactants in the food industry is strictly limited and cannot cause harm to the human body.
The surface active agents 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 tartrate mono- and diglycerides, diacetyl tartrate mono- and diglycerides , Citric acid ester, polyglyceryl fatty acid and ricinoleic acid ester, stearoyl citric acid and tartrate, calcium stearoyl lactate (sodium), sodium stearoyl fumarate, sorbitan fatty acid ester, polyoxyethylene Ethylene (20) and (40) stearate, etc. Polymer surfactants, such as sodium alginate, sodium pectinate, carrageenan, chitosan water-soluble protein, etc. Most of them are semi-synthetic polyol nonionic surfactants, among which soybean phospholipids and some polymer surfactants are natural products.
The main role of surfactants in food
Emulsifiers usually have hydrophilic groups (hydroxyl groups, etc.) and lipophilic groups (alkyl groups) in the molecule, which easily form an adsorption layer on the interface between water and oil. They are surfactants and can be divided into water-in-oil type and oil-in-water type. There are two types. The total number of available emulsifiers is about 65, among which are fatty acid glycerides (mainly monoglycerides), fatty acid sucrose esters, fatty acid sorbitan esters, fatty acid propylene glycol esters, soy phospholipids, gum arabic, alginic acid, caseinic acid Sodium, gelatin, egg yolk, etc. Emulsifiers can improve the surface tension between the various components in the emulsified body, so that it can form a uniform dispersion or emulsified body, thereby improving the texture and appearance of the food structure, and improving the preservation of food.
Surfactants, as emulsifiers, play an extremely important role in the food industry and provide good conditions for the development of the food industry. It can be said that all walks of life in food processing cannot do without emulsifiers. The following briefly describes the main functions of emulsifiers used in various processed foods.
Bread and eggs: Prevent the hydrophobic effect of amylose in wheat flour, thereby preventing aging and regenerating, reducing dough viscosity, easy to operate, promoting the formation of gluten structure, improving foaming, and making the pores dispersed and dense, promoting the emulsification and dispersion of shortening, thereby Improve organization and taste. For example, adding 0.2%~0.3% monoglyceride of flour to bread can effectively prevent aging and make flour soft. Adding 0.2% to 0.5% of sucrose esters (above HLB11) in the amount of flour can improve the foaming effect and has wettability, making the bread cake softer.
Thickener is a kind of additive that can increase food viscosity or form gel. It has the function of stabilizing emulsification or suspension state. It is a hydrophilic polymer compound, generally called polymer surfactant, also known as viscosity regulator, glue Coagulant and emulsion stabilizer, etc. There are nearly 40 species in total, divided into two categories: natural and chemical synthesis.
Most natural thickeners are made from plants and seaweeds containing polysaccharide mucilage, such as starch, gum arabic, guar gum, carrageenan, pectin, agar, and alginic acid. It is also made from plants and animals that contain protein, such as gelatin, casein, and sodium hydrazine. Some are made from microorganisms, such as xanthan gum (xanthan gum) and so on. Synthetic thickeners, such as sodium carboxymethyl cellulose CMC, propylene glycol alginate, cellulose glycolic acid and sodium polyacrylate, sodium starch glycolate, sodium starch phosphate, methyl cellulose and sodium polyacrylate, etc.
Polymer surfactants generally have the following characteristics: low ability to reduce interfacial tension, most do not form strands, weak penetration, poor foaming power, but the foam formed has good stability and emulsifying power, excellent dispersion and cohesion. They are mostly used in sauces, jams, ice cream, canned food, candy and instant noodles. For example, sodium carboxymethyl cellulose has the characteristics of viscosity, stability, and film formation. Therefore, it can be used in ice cream to improve water retention and tissue structure. It can be used as a foam stabilizer for beer. It can also be used for jam, butter, and peanut white. It can improve the spreadability. It has strong swelling properties after absorbing water and is not easy to digest. It can be used as diet food such as biscuits.
In addition to being used as emulsifiers/thickeners in food production, surfactants can also be used as dispersants, wetting agents, foaming agents, defoamers, crystallization control agents, bactericides, etc., as well as prolonging food preservation period effect.
Surfactants are used as dispersants and wetting agents to improve the hydrophilicity and dispersibility of powdered foods such as milk powder and cocoa powder. When the whole milk powder is granulated, 0.2%~0.3% soy lecithin is added, which can quickly dissolve without agglomeration during preparation. According to reports, a finished product with a phospholipid content of about 0.35% to 0.5% by weight can be wetted and dispersed in water at 6°C in less than 10 minutes, and its wettability can remain stable for more than one year at room temperature. The humectant will not bring bad taste or smell to the rehydrated beverage. Cocoa powder has fine particles and an oily film on the surface, which is difficult to disperse. Sucrose esters can improve its dispersibility. In the production of cakes, ice cream, etc., adding monoglycerides can increase the degree of fat dispersion, produce a fine pore-shaped structure, and improve eating quality.
Surfactants are widely used in the food industry. Adding surfactants in some food preparations can greatly improve processing conditions, improve product quality, and extend food preservation periods. For example, in the production of ice cream, without surfactants, the quality structure of the product cannot be controlled, and the expansion rate cannot be improved. Another example is microencapsulation technology. Without the good emulsification and film-forming properties of surfactants, embedding is difficult. get on. In general, high-quality food processing is inseparable from the application of surfactants. The wide application of surfactants has greatly promoted the development of the food additive industry.
With the continuous improvement of people's living standards, people's demand for food nutrition, quality and variety diversification continues to increase, and the application of surfactants in the food industry will get greater development.