Emulsifiers in Dairy Products: Types, Functions, and Superior Performance

Emulsifiers are indispensable food additives in the modern dairy industry. They enable immiscible liquids like oil and water to form stable emulsions, significantly improving product texture, stability, and shelf life. In dairy products, emulsifiers not only play a classic emulsifying role but also possess multiple functions such as foaming, suspension, crystallization control, and interaction with proteins and starch. As consumers increasingly demand clean labels, healthy options, and premium sensory experiences, the application of emulsifiers in dairy products has become increasingly important. This article will systematically introduce the types of emulsifiers commonly used in dairy products, their mechanisms of action, and those that have superior effects on dairy texture, stability, and shelf life.

1.What are Emulsifiers?

Food emulsifiers are substances that can improve the surface tension between various constituent phases in an emulsion system, forming uniform dispersions or emulsions, also known as surfactants. Their molecules contain both hydrophilic and lipophilic (hydrophobic) groups-hydrophilic groups can bind with water molecules, while lipophilic groups can bind with oil molecules. This amphiphilic structure enables them to position themselves at the oil-water interface, reducing surface tension and preventing droplet coalescence.

2.HLB Value of Emulsifiers

HLB (Hydrophilic-Lipophilic Balance) is an indicator of the balance between the hydrophilic and lipophilic properties of emulsifiers, expressed as a numerical value from 0 to 20. Smaller values indicate higher lipophilicity, while larger values indicate higher hydrophilicity. HLB value is an important reference when selecting emulsifiers for specific applications:

• High HLB (>10): Hydrophilic emulsifiers, suitable for oil-in-water (O/W) emulsions such as milk, cream, and ice cream
• Low HLB (<6): Lipophilic emulsifiers, suitable for water-in-oil (W/O) emulsions such as butter and margarine

1.Mono- and Diglycerides of Fatty Acids (E471)

Mono- and diglycerides of fatty acids are among the most commonly used food emulsifiers and are widely applied in dairy products. They are produced by esterification of glycerol with fatty acids, offering good emulsifying properties and safety. Glycerol monostearate has an HLB value of approximately 3.8, classifying it as a water-in-oil emulsifier, but it can form hydrates in the aqueous phase, exhibiting a false HLB value of about 7.2, making it suitable for oil-in-water systems as well.

2.Sucrose Esters of Fatty Acids (E473)

Sucrose esters of fatty acids are produced by esterifying sucrose with fatty acids. Their hydrophilic groups contain up to 8 hydroxyl groups, allowing for products with a wide range of HLB values. High HLB sucrose esters (e.g., HLB 15) exhibit excellent emulsifying effects in milk, rapidly surrounding fat droplets dislodged during homogenization and forming a complete interfacial membrane.

3.Lecithin (E322)

Lecithin is a natural emulsifier extracted from natural foods such as soybeans. The molecular structure of soy lecithin can stably bind with fat globules. Research shows that cream added with soy lecithin has a smaller average particle size, effectively reducing fat globule dimensions. In recombined and concentrated milks, the interaction between lecithin and proteins can improve heat stability.

4.Polyoxyethylene Sorbitan Esters (Polysorbates, E432-E436)

Polyoxyethylene sorbitan esters are efficient oil-in-water emulsifiers commonly used in coffee creamers, whipping cream, and ice cream. They have high HLB values, providing excellent emulsifying stability and foaming properties.

5.Sodium Stearoyl-2-Lactylate (E481)

Sodium stearoyl-2-lactylate (SSL) is an anionic emulsifier with an HLB value of 8.3, classifying it as an oil-in-water type. It can undergo electrostatic interactions with milk proteins and can be used to alter texture in processed cheese. In coffee creamers, the interaction between proteins and SSL can improve acid stability.

6.Organic Acid Esters of Mono- and Diglycerides

These include lactic acid esters of mono- and diglycerides (E472b), mono- and diacetyl tartaric acid esters of mono- and diglycerides (DATEM, E472e), and acetic acid esters of mono- and diglycerides (E472a). These emulsifiers play important roles in aerated dairy products such as mousse and whipped cream, producing and maintaining air bubbles to form fine, regular, and highly stable air structures.

7.Polyglycerol Esters of Fatty Acids

Polyglycerol esters of fatty acids can combine with up to 12 fatty acids, allowing for products with a wide range of HLB values. They offer good emulsifying properties and stability in dairy products.

1.Liquid Milk

Pure milk is prone to fat flocculation during storage and transportation, affecting product quality. During homogenization, fat globules are broken into smaller fat globules, increasing surface area by 6-10 times. The natural emulsifiers in raw milk (lecithin, casein) are insufficient to meet the needs of the fat interfacial membrane, making it necessary to add appropriate emulsifiers.

Key Emulsifiers:

• High-HLB Sucrose Esters (HLB 15): Rapidly migrate to the fat-serum interface during homogenization, forming a complete interfacial film.
• Hydrophilic Monoglycerides (HLB 9.0): Provide excellent emulsification effects.
• Lecithin (E322): Binds stably to fat globules, reducing their size.

HLB Optimization:

Research shows that when the HLB value of mixed emulsifiers is around 9.0, it achieves both good emulsifying effect (high absorbance after homogenization) and ensures stability during sterilization and storage (small change in absorbance before and after centrifugation).

2.Cream and Whipped Cream

Cream is an O/W system with fat content up to 36%, and the average distance between fat globules is only 0.96μm, making fat easily coalesce during manufacturing. Emulsifiers in these products need to achieve multiple functions: promoting emulsion stability, improving whippability, and enhancing foam stability.

Key Emulsifiers:

• Polysorbates (E432–E436): Used in coffee creamers and whipping cream to improve dispersibility and whitening properties.
• Organic Acid Monoglycerides (E472a, E472b): Used in non-dairy creamers to generate and stabilize air bubbles, providing a stable texture.
• Activated Emulsifiers (e.g., LASENOR® TP): Specifically designed for whipping cream to ensure efficient aeration, structural stability, and adjustable viscosity.

HLB Optimization:

Research shows that the optimal HLB value for cream emulsifiers is around 7.4. Within the HLB range of 4-7.4, as HLB decreases, the volume average particle size of cream gradually decreases; as HLB continues to increase, particle size also gradually increases.

3.Ice Cream

Ice cream is one of the most complex food colloids-a gas-liquid-solid three-phase system containing fat, proteins, sugars, gums, and emulsifiers. Emulsifiers play multiple key roles in ice cream.

Key Emulsifiers:

• Mono- and Diglycerides (E471): Most commonly used; provide a smooth, fine texture and reduce melting rate.
• Polysorbates (E432–E436): Improve whipping performance and stabilize air bubbles.
• Sucrose Esters of Fatty Acids (E473): Aid in emulsification and stabilization.

Mechanism:

Emulsifiers in ice cream stabilize the foam structure by promoting partial coalescence of fat. During freezing, emulsifiers displace proteins from the fat globule surface, making fat globules more prone to partial coalescence, forming a three-dimensional network structure that supports air bubbles and delays melting.

4.Yogurt and Fermented Dairy Products

Yogurt is a gel-like product produced by bacterial fermentation of milk. The addition of emulsifiers improves mouthfeel, enhances creaminess, and aids fat dispersion. In fermented dairy products, preventing syneresis (whey separation) is key to quality control.

Key Emulsifiers:

• Mono- and Diglycerides (E471): Improves mouthfeel and fat dispersion
• Sucrose Esters of Fatty Acids (E473): Aids in stabilization
• Compound Stabilizer Systems (e.g., SWISSGUM® D): Gelatin-free formulation; improves mouthfeel and reduces whey separation; suitable for set-type or stirred-type yogurts

Superior Performance:

Modern compounded emulsifier-stabilizer systems significantly improve yogurt texture and stability. For example, the SWISSGUM®D series offers gelatine-free solutions, improves mouthfeel, prevents syneresis, and is suitable for vegetarian and organic products.

5.Processed Cheese

In processed cheese, fat droplets are dispersed in a concentrated gelled protein network, with emulsion stability primarily controlled by casein. Adding emulsifiers achieves a smooth texture, reduces microbial growth, and lowers the amount of emulsifying salts required to obtain high-quality cheese.

Key Emulsifiers:

Mono- and Diglycerides (E471): Most commonly used

Acetylated Monoglycerides (E472a): Used in cheese coatings

Sodium Stearoyl Lactylate (E481): Anionic emulsifier; undergoes electrostatic interactions with proteins to modify texture

Mechanism:

In processed cheese, electrostatic interactions between anionic emulsifiers and proteins can be exploited to adjust texture. Compounded stabilizing systems can also provide textures ranging from honey-like to spreadable, ensure no syneresis, and control viscosity during filling.

1 Texture Optimization

2.Stability Enhancement

3 Shelf Life Extension

4 Key Emulsifiers with Multiple Superior Properties

1. Mono- and Diglycerides (E471)

As the most versatile dairy emulsifier, mono- and diglycerides exhibit superior performance in various products: providing smooth texture and melt resistance in ice cream; achieving smooth texture in processed cheese; improving mouthfeel in yogurt; and through HLB optimization, achieving optimal emulsification stability in liquid milk.

2. Organic Acid Ester Series (E472a, E472b, E472e)

This group of emulsifiers excels in aerated dairy products: producing and maintaining fine bubbles in whipped toppings and desserts; DATEM (E472e) providing excellent performance in coffee creamers; and lactic acid esters (E472b) adding different textures to desserts.

3. Sodium Stearoyl-2-Lactylate (E481)

SSL demonstrates unique advantages in various dairy products: adjusting texture through electrostatic interactions in processed cheese; synergizing with proteins to improve acid stability in coffee creamers; and serving as a common emulsifier in whipped cream.

4. Compounded Emulsifier-Stabilizer Systems

Modern compounded systems such as SWISSGUM®D and LASENOR®TP represent the latest developments in emulsifier applications: customized formulations for specific products (yogurt, cheese, beverages, desserts); meeting clean label trends (gelatine-free, BPA-free, suitable for vegetarians); simultaneously addressing multiple quality issues (preventing syneresis, improving mouthfeel, controlling viscosity, extending shelf life).

Emulsifiers play irreplaceable multifunctional roles in dairy products, from basic emulsification stabilization to complex texture control, crystallization regulation, and shelf life extension. Different types of emulsifiers, through their unique molecular structures and HLB values, demonstrate respective advantages in various dairy products.

Key Findings:

1. HLB optimization is crucial: In liquid milk, mixed emulsifiers with HLB around 9.0 show optimal effects; in cream, the most suitable HLB is approximately 7.4.
2. Synergy between emulsifiers is significant: High HLB emulsifiers provide good emulsifying effects, while low HLB emulsifiers provide stability; their combination achieves optimal performance.
3. Interaction with proteins is a key mechanism: Electrostatic interactions and synergies between emulsifiers and milk proteins (especially casein) determine product stability and texture.
4. Compounded systems represent development trends: Compounded emulsifier-stabilizer systems for specific applications can simultaneously address multiple quality issues, meeting market demands for clean labels and healthy choices.

As consumers increasingly focus on clean labels, natural ingredients, and healthy choices, the development of dairy emulsifiers is moving towards natural sources, multifunctionality, and sustainability. In the future, we can expect to see more plant protein-based emulsifiers, and innovative emulsifier systems that meet specific dietary requirements (such as high-protein, low-fat, allergen-free).

When used in compliance with regulations, emulsifiers are safe for consumer health when used according to the varieties, application scopes, and dosages specified in GB 2760-2024 "National Food Safety Standard for Uses of Food Additives". When selecting emulsifiers, dairy manufacturers should comprehensively consider product characteristics, processing technology, target market regulations, and consumer needs to optimize product quality and meet market demands.