Application of Zwitterionic Surfactant in Food Industry

With the improvement of living standards, people have higher expectations for food. Beyond satisfying basic nutritional needs, food is also expected to have appealing color, aroma, and taste. Therefore, food additives are increasingly used in the food industry, and one of the most common types is the zwitterionic surfactant.

A zwitterionic surfactant is a compound that contains both hydrophilic and lipophilic groups within its molecule. It can accumulate at the surface of a solution, at the interface of two immiscible liquids, or at the interface between a liquid and a solid, thereby reducing surface or interfacial tension. Zwitterionic surfactant plays an important role in the food industry by improving processing conditions, enhancing product quality, and extending shelf life. High-quality food production is inseparable from the use of zwitterionic surfactant.

Zwitterionic Surfactant as an Emulsifier

• The primary function of an emulsifier is to stabilize an emulsion. In food applications, maintaining stability is more critical than the initial dispersion. Instability such as aggregation is undesirable. Hydrophilic monoglycerides are especially effective in stabilizing emulsions.

  
  

• Chemically synthesized monoglyceride has not only the advantages of molecularly distilled monoglyceride, but also superior emulsifying, defoaming, foaming, and foam-stabilizing properties.

  
  

• Hydrophilic monoglyceride is a high-quality and efficient food emulsifier and zwitterionic surfactant. It is widely used in bread, pastries, biscuits, margarine, chocolate, ice cream, instant noodles, soy products, and protein beverages. It offers excellent emulsifying stability, dispersion, defoaming, freshness preservation, and prevention of starch retrogradation. It is internationally recognized as non-toxic and approved for unlimited use in food.

  
  

• Zwitterionic surfactant is also widely applied in plastics, rubber, textile, cosmetics, and pharmaceuticals. In addition to emulsifying, it also helps with anti-settling, anti-aging, and regulating fatty acid aggregation. It is a typical nonionic zwitterionic surfactant.

  
  

Emulsifiers typically contain hydrophilic groups (e.g., hydroxyl) and lipophilic groups (e.g., alkyl), enabling them to form adsorption layers at water–oil interfaces. As a zwitterionic surfactant, an emulsifier can be either water-in-oil (W/O) or oil-in-water (O/W). There are about 65 usable types, with common ones including fatty acid glycerides (mostly monoglycerides), sucrose esters, sorbitan esters, propylene glycol esters, soy lecithin, gum arabic, alginic acid, sodium caseinate, gelatin, and egg yolk. These emulsifiers reduce interfacial tension, form stable emulsions or dispersions, and thus improve food structure, taste, appearance, and shelf life.

As an emulsifier, zwitterionic surfactant plays an essential role in food industry and supports the development of modern food processing. Nearly all sectors in food manufacturing depend on emulsifiers. Below are examples of its main functions in different types of processed foods:

In Bread and Egg-based Products

It prevents the retrogradation of amylose in wheat flour, reduces dough stickiness, improves workability, promotes gluten formation, enhances foaming properties, creates a fine, uniform crumb structure, and facilitates emulsification of shortening. For example, adding 0.2%–0.3% monoglyceride (based on flour weight) helps prevent staling and keeps the product soft. Adding 0.2%–0.5% sucrose ester (HLB >11) enhances foaming and moisture retention, giving the bread or cake a softer texture.

Zwitterionic Surfactant as a Thickener

A thickener increases the viscosity of food or forms a gel and helps stabilize emulsions or suspensions. It belongs to hydrophilic high molecular compounds and is generally called a high-molecular-weight zwitterionic surfactant, also referred to as a viscosity modifier, gelling agent, or emulsification stabilizer. There are nearly 40 types of thickeners, both natural and synthetic.

Natural thickeners are mostly derived from plants and seaweeds rich in polysaccharides, such as starch, gum arabic, guar gum, carrageenan, pectin, agar, and alginic acid. Others come from proteins in animals and plants, such as gelatin, casein, and sodium caseinate. Some, such as xanthan gum, are microbial in origin.Synthetic thickeners include sodium carboxymethyl cellulose (CMC), propylene glycol alginate, cellulose acetate, sodium polyacrylate, starch acetate, starch phosphate, methylcellulose, and others.

As consumers demand more nutritious, higher-quality, and more diverse food products, the use of zwitterionic surfactant in food industry will continue to grow and play a critical role in advancing food processing technology.