Emulsifiers Explained: A Practical Guide for Formulators
What Is an Emulsifier?
Emulsifiers are surface-active agents that aid in the interaction of two or more immiscible phases (e.g., water, oil, and air) that promote the formation and stabilization of emulsions and foams. Emulsifiers are amphiphiles; they contain both a hydrophilic part, which favors interaction with water, and a hydrophobic part, which favors interactions with lipids and air. Emulsifiers are represented by a large class of substances and are utilized in a variety of food and non-food applications. The term "emulsifier" is somewhat of a misnomer since emulsification is just one of a range of functions, including the following:
- Starch Complexing
- Protein Interaction
- Aeration and Stabilization
- Crystal Modification
- Oil Structuring
- Lubrication and Processing Aids
Managing the Interface
Emulsifiers are one tool used to meet today’s challenge of maintaining processed food’s quality, safety, and integrity. “Emulsifier” is a broad term to identify surface-active agents that change the surface properties of the materials they come in contact with. Other names for emulsifiers include “surface-active agents,” “surfactants,” and “stabilizers.”
Foods and beverages are complex systems containing interfaces among ingredients such as fats, proteins, starches, water, and air. Emulsifiers provide the means to manage these interfaces, interactions, and transitions, allowing the preservation of texture, flavor, etc.
For example, emulsifiers can do the following:
- Inhibit staling by delaying the retrogradation of starch in breads and related grain-containing products
- Improve machinability by reinforcing the gluten matrix in bread dough
- Shorten the texture by improving the distribution of fat in a cake batter
- Allow incorporation of air by desorbing the milk protein from the interface in ice cream
- Maintain gloss, snap, and flavor by delaying the crystal transition of the cocoa butter fat in chocolates
- Reduce fat content by modifying the viscosity and yield value of chocolate, to aid in processing
- Increase shelf life by delaying the separation of oil (creaming) in salad dressings
Starch Complexing
Certain emulsifiers can interact with starch (amylose) to form water-insoluble complexes, which aid in the processing of starch-based products, such as pasta, potatoes, and extruded products. In baked goods, such complexes delay the retrogradation (recrystallization) of the starch, commonly associated with the mechanisms of staling. Emulsifiers like distilled monoglycerides and lactylates can provide shelf-life extension and are often referred to as crumb softeners.
Distilled monoglycerides based on fully hydrogenated fats are especially suitable as starch complexing agents, as they are easily entrapped by the helical configuration of amylose to form a complex that is insoluble in water.
Emulsification
Many processed foods, such as margarines, nondairy creamers, beverages, and cake batters, are emulsions where one phase is dispersed in another. For example, a nondairy creamer is an emulsion where a fat or oil is dispersed throughout an aqueous protein phase.
During the process, mechanical shear is facilitated by impellers or by homogenization and provides energy to disperse the fat phase. Emulsifiers can initially aid in the formation of the emulsion by reducing the surface tension for a given amount of energy, allowing a greater interfacial surface (smaller droplet size).
In certain cases, emulsifiers can also provide stabilization of the emulsion by various mechanisms, such as particulate and electrostatic stabilization. These mechanisms are determined by the molecular structure and ionic nature of the emulsifier.
In addition, due to the interfacial properties, emulsifiers can serve as wetting agents, both in the process (dispersing other components) and in the final product, as a way to improve mouthfeel and flavor release.
One example is using liquid emulsifiers like Atmos® 300 to incorporate fat-soluble flavors and colors into water-based beverages such as sports drinks.
Protein Interaction
Emulsifiers can interact with proteins in a variety of foods. Protein interactions can affect volume in baked goods, as well as mouthfeel in sauces and gravies, and they can stabilize dairy and nondairy systems.
Certain emulsifiers can interact with the protein of yeast-raised baked goods. They reinforce the gluten structure and improve the dough’s viscoelastic properties. Such interactions provide greater gas retention and better tolerance to proof and mechanical shock that may be experienced on today’s modern high-speed lines. Emulsifiers like lactylates (e.g., Emplex® SSL and Verv® CSL) and DATEM reinforce the gluten structure via sulfide bonding. Others, like ethoxylated monoglycerides and polysorbates, reinforce the gluten network via hydrogen bonding.
In addition to our single emulsifiers, PATCO also offers several emulsifier blends, such as Xpando®, to optimize baking success.
For sauces, gravies, and nondairy creamers, emulsifiers interact with proteins to improve mouthfeel and increase stability. Ionic emulsifiers, such as Emplex® (SSL), are typically used in these applications.
Given the complex nature of protein interactions within a specific food system, PATCO can customize the best solution for your application.
Aeration and Stabilization
Aerated foods (cake batters, imitation creams, etc.) are more complex emulsions since they are oil-in-water (aqueous protein phase) emulsions that also incorporate and require the stabilization of air cells. Emulsifiers are typically employed to strengthen the air cell network.
In general, emulsifiers are critical for producing the desired crumb structure and volume for cakes. A section of the industry prefers using liquid oils. This presents its own challenges. In layer or high-ratio cakes that use liquid oil rather than a structured shortening, a combination of emulsifiers can aid in aeration by encapsulating the liquid oil and preventing defoaming. This enables the cake batter to become aerated during the mixing process.
Alpha-tending emulsifiers hold the monoglycerides in the preferred mesophase (alpha gel) that provides structure to the air cells. This allows entrapment of air until the baking process sets the foam structure. Vanlite is an excellent alpha-tending emulsifier system.
Ice cream is an example where an emulsifier is needed to destabilize an existing emulsion to allow for air incorporation. Proteins can be extremely strong emulsifiers and prevent aeration. Adding emulsifiers, such as Alphadim® 570 or BFP® 75K, partially displaces the proteins at the interface and allows for the creation of stable foams.
Crystal Modification
Fat can exist in more than one polymorph (crystalline form). The number of polymorphs depends on the type of fat. For example, palm oil has three polymorphs (alpha, beta prime, and beta), whereas cocoa butter can exist in many more. Certain polymorphs are more stable or desired than others, depending on the application. Process conditions and emulsifiers can be used to promote and retain the desired crystal form.
Emulsifiers can enhance the appearance and texture of chocolates and coatings by maintaining gloss and snap. During storage and transportation, the fat crystals can undergo polymorphic transitions, resulting in a fat bloom (mottling) on the surface and producing a dull appearance. These transitions can negatively impact the organoleptic properties associated with flavor and texture. Certain emulsifiers, such as lactic acid esters (BFP® GLP), sorbitan esters, and polysorbates, can delay or retard such transitions and increase the shelf life.
Other emulsifiers, such as distilled monoglycerides and mono- and diglycerides, can modify the set point of confectionery products. Modifying the set point can, in turn, increase production throughput and improve tolerance to adverse storage conditions.
Confections such as chews and caramels contain emulsifiers like mono- and diglycerides to maintain their plasticity or chewing properties during storage.
Oil Structuring
Traditionally, processors have relied on solid fats to provide structure in food systems. Trans-fat shortenings delivered the desired crumb structure to baked goods and creaminess to table margarines. With the advent of new dietary guidelines, many processors have moved away from trans-containing shortening and toward incorporating more nutritionally desirable liquid oils in their applications. These reformulations created challenges in maintaining the necessary structuring for these systems. For example, when switching to a mostly liquid-oil system, a fried donut has a greasier surface, and puff pastry loses its characteristic light, airy structure.
Trancendim®, a line of customized diglycerides, can provide the required structure to liquid oil while keeping saturated fat content low and eliminating trans fat. These emulsifiers have excellent crystallization properties that lead to a network of small, beta prime crystals that entrap the liquid portion of the shortening system. The result is a shortening comparable to the traditional trans-containing versions, with improved nutritional value and the same desired eating qualities.
Outside of shortening applications, Trancendim® can reduce oil and moisture migration between two or more layers in a food system. Nut butters, which typically contain about 50% liquid oil, can separate over time. The addition of Trancendim® will delay this separation and lead to a more desirable product.
Lubrication and Processing Aids
Mono- and diglycerides, as well as distilled monoglycerides, are used as lubricants and processing aids in extruded products such as pasta, pet food, and breakfast cereals. These emulsifiers provide product release from packaging or equipment. They also work in systems like caramels, fruit leathers, and gum as plasticizers to improve chewing quality and prevent stickiness.
The Trancendim® product line is an excellent processing aid in situations ranging from high-speed bread-slicing operations to preventing stacks of tortillas from sticking to one another.
Choosing an Emulsifier
Emulsifiers are very versatile food ingredients. Many factors go into selecting the correct emulsifier for your application, including desired functionality, interaction with other ingredients, processing equipment, regulatory guidelines, and more. If you have questions regarding any of these categories, a technical expert here at ChemPoint would be happy to assist you in finding the right emulsifier solution or check out our emulsifier selector guide below.
