If you’ve just noticed Polysorbate 80 on a food label and are curious about its function, you’re not alone. Polysorbate 80 is a common food ingredient with numerous applications in the food business. It is a synthetic molecule with emulsifying capabilities created from sorbitol and oleic acid. It essentially allows the blending of materials that would normally separate, such as oil and water. Polysorbate 80, which is commonly found in processed meals, baked goods, ice cream, and salad dressings, serves an important role in providing a smooth and consistent texture in these products.

Let’s discuss further.

WHAT IS POLYSORBATE 80?

Polysorbate 80 is a versatile compound widely used in the food and pharmaceutical industries. It belongs to the family of polysorbate surfactants. This synthetic substance is derived from sorbitol, a sugar alcohol, and oleic acid, a fatty acid obtained from natural sources like olive oil. The resulting compound polysorbate 80, also known as Tween 80, exhibits exceptional emulsifying properties due to its unique chemical structure.

It is composed of a hydrophilic (water-attracting) polyoxyethylene chain and a lipophilic (fat-attracting) sorbitan ester chain, The lipophilic section, derived from sorbitan and oleic acid, anchors the compound within fat-based substances. This dual nature enables Polysorbate 80 to form micelles. These micelles are small structures in which the hydrophobic tails cluster together while the hydrophilic heads extend outward. This produces a stable emulsion. This property is particularly useful in the manufacture of smooth and consistent textures in items like ice cream, salad dressings, and baked goods.

Polysorbate 80 is assigned the European food additive number E433. The E numbers, or E additives, are codes for substances that are added to food for various purposes such as coloring, preservation, and emulsification. In the case of Polysorbate 80, its E number, E433, reflects its role as an emulsifier and stabilizer in food products.

HOW IS IT MADE?

The synthesis of Polysorbate 80 is a meticulously controlled, multi-step process. It begins with the esterification of sorbitol, a hexavalent sugar alcohol, using fatty acids derived mainly from natural oils such as olive oil. Esterification, a chemical process involving the reaction between an organic acid (with a carboxyl group, -COOH) and an alcohol (with a hydroxyl group, -OH), leads to the formation of sorbitan esters in the initial chemical reaction.

The sorbitan esters go through through ethoxylation, a key step involving the introduction of ethylene oxide under catalyst influence. The addition of ethylene oxide imparts hydrophilic (water-attracting) properties to the molecule, making it more soluble in water. Following this, purification steps employing distillation and filtration methods are implemented to remove any residual reactants and impurities. This is a critical step as the presence of impurities can affect the properties and performance of the final product.

The final manufacturing stage involves neutralization to attain the desired pH level. Polysorbate 80 is a nonionic surfactant, and its stability and effectiveness can be influenced by pH. Neutralization helps to stabilize the molecule and ensures that it remains compatible with a wide range of other ingredients commonly used in various products, including pharmaceuticals, cosmetics, and food.

FUNCTIONS IN FOOD

As emulsifier

In the emulsification process, Polysorbate 80 aligns at the interface between water and oil phases. The hydrophilic heads extend into the water, while the lipophilic tails immerse into the oil, creating micelles—tiny structures that encapsulate and disperse oil droplets within the water. This arrangement prevents the oil droplets from coalescing and separating, resulting in a stable and homogenous emulsion.

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Polysorbate 80 is a common ingredient in baked goods, salad dressings, and ice cream. For example, it contributes to the smooth and creamy texture of ice cream, which enhances the desired mouthfeel. A complex blend of water, fat, sugar, and other substances makes up ice cream. These ingredients may have a tendency to separate in the absence of an emulsifier, giving the finished product an undesirable texture. Particularly the fat and water components naturally oppose one another, which leads to the production of ice crystals and an unsatisfactory consistency. Polysorbate 80 facilitates the coexistence of fat and water molecules by acting as a bridge. As a result, the ice cream keeps its uniform composition.

As anti-foaming agent

One of Polysorbate 80’s important properties is its capacity to lower surface tension, which aids in the destabilization of foam bubbles. Surface tension is a liquid attribute caused by the cohesive interactions between molecules at the liquid’s surface.

Foam is a mixture of gas bubbles scattered throughout a liquid or solid. Excessive foam can make industrial processes less effective. For example, uncontrolled foam formation in the food and beverage industry can result in uneven mixing, erroneous measurements, and variations in the quality of the finished product.

This is particularly true during mixing, blending, and cooking. For example, during the manufacture of candies and aerated treats, foaming may lead to the formation of undesirable air pockets in the final product. With the addition of Polysorbate 80, foaming is kept to a minimum during cooking, ensuring that confections set correctly.

Polysorbate 80’s anti-foaming properties also find application in the beverage industry, particularly in the production of carbonated drinks and beer. Excessive foam in these products can lead to inefficiencies in filling and packaging, as well as affect the sensory characteristics of the final beverage.

As wetting agent

Polysorbate 80 not only as an effective anti-foaming agent, and emulsifier, but also as a wetting agent (or surfactant). Wetting agents help overcome issues related to poor dispersion and solubility of certain components in food formulations. With its capacity to enhance the wetting properties of specific ingredients, Polysorbate 80 facilitates their seamless incorporation into food products. This property proves particularly beneficial in various applications, ranging from baked goods to sauces and dressings.

Flour, a fundamental ingredient in baking, tends to form clumps and resist hydration. Incorporating polysorbate 80 combats this issue by reducing the surface tension between flour particles and liquid components. This results in improved dispersion, allowing for a smoother, lump-free batter or dough. The even wetting of flour helps achieve a consistent texture and uniformity in the final baked product.

The versatility of Polysorbate 80 as a food additive makes it a preferred choice for manufacturers seeking multifunctional ingredients to streamline their processes. Its nonionic nature allows it to interact effectively with a diverse array of ingredients without compromising the sensory attributes of the final product.

SAFETY CONCERNS

After reviewing Polysorbate 80, the US Food and Drug Administration (FDA) declared it to be generally recognized as safe (GRAS) for use in a variety of food products at certain concentrations. This classification indicates that the use of Polysorbate 80 is thought to be safe for human consumption when used within certain bounds, according to the available scientific data.

Following thorough safety assessments, encompassing evaluations of genotoxicity, carcinogenicity, and developmental toxicity, the European Food Safety Authority (EFSA) established the Acceptable Daily Intake (ADI) for polysorbate 80 at 25 mg/kg body weight per day.

To guarantee safety, both the FDA and EFSA underscore the significance of following the recommended usage levels. For example, the maximum amount of polysorbate 80 permissible in ice cream is 0.1%.

Regulators have determined that Polysorbate 80 is safe, but some people may have mild side effects. Allergy-related side effects, like gastrointestinal distress or skin irritation, have been reported. These reactions, though, are usually uncommon and only happen to people with particular sensitivities. These adverse effects are marginally more likely to occur in people who take large doses of Polysorbate 80 or who are exposed for an extended period of time. It’s critical to be aware of these possible dangers, and to get medical help if you take Polysorbate 80 and notice any unsettling side effects.

It’s important to note that the majority of consumers can safely consume products containing Polysorbate 80 without adverse effects.

The post What Is Polysorbate 80 (E 433) In Food? appeared first on The Food Untold.

When you indulge in a piece of chocolate, you probably don’t give much thought to the ingredients that go into making it. However, one ingredient that you may come across in the list of chocolate additives is polyglycerol polyricinoleate, commonly known as PGPR. This tongue-twisting compound plays an essential role in the production of chocolate and contributes to its smooth texture and mouthfeel.

In this article, we will explore what PGPR is, how it is made, and its significance in the world of chocolate.

WHAT IS POLYGLYCEROL POLYRICINOLEATE?

Polyglycerol polyricinoleate or PGPR is a food emulsifier derived from the seeds of the castor oil plant. With its excellent emulsifying properties, PGPR effectively combines fat and water-based ingredients, ensuring they remain mixed without separation. In chocolate production, PGPR plays a crucial role in creating a desirable smooth and creamy texture by effectively binding cocoa solids and cocoa butter together.

As an emulsifier, PGPR is denoted by the E number E476.E numbers are codes for substances used as food additives in the European Union. In the region, PGPR is permitted in cocoa-based confectionery and chocolates up to 5 g/kg.

HOW IS IT MADE?

Castor oil, which is produced from the seeds of the castor plant (Ricinus communis), is the primary source of PGPR. The oil contains ricinoleic acid, a fatty acid that undergoes esterification. Esterification is a chemical process that occurs when an organic acid (RCOOH) reacts with an alcohol (ROH) to produce an ester (RCOOR) and water.

In the instance of PGPR manufacturing, ricinoleic acid interacts with glycerol, a trihydroxy alcohol, to generate polyricinoleate. The hydroxyl (-OH) groups in glycerol are substituted with the carboxylic acid (-COOH) groups of ricinoleic acid during this process. Polyglycerol is then created by polymerizing glycerol molecules, which entails connecting glycerol units to form chains of variable lengths. The polymerization process is typically catalyzed by an acid catalyst or enzymes.

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The final step involves combining the polyricinoleate and polyglycerol. The polyglycerol chains intertwine with the polyricinoleate chains, forming a complex structure. This combination enhances the emulsifying properties of the final product.

The resulting PGPR is a yellowish, viscous liquid with excellent emulsification capability.

FUNCTIONS OF POLYGLYCEROL POLYRICINOLEATE (PGPR) IN CHOCOLATE

One of the most commonly used ingredients in chocolate is lecithin, which acts as a food additive to reduce viscosity, improve flow properties, and extend the shelf life of chocolate. However, many chocolate manufacturers prefer to use PGPR due to its lower cost compared to lecithin. Lecithin is a naturally sourced emulsifier typically extracted from soybeans and, to a lesser extent, from eggs. However, the extraction and refining processes for lecithin can be more complex, requiring additional steps. Similarly, cocoa butter, another commonly used emulsifier, is also expensive. By opting for PGPR instead of lecithin, chocolate manufacturers can reduce production costs without compromising the overall quality of the chocolate.

Viscosity control

During chocolate manufacturing, PGPR helps control viscosity, the resistance of a fluid to flow. Chocolate needs to flow smoothly during various production steps, such as tempering, molding, and coating. Proper viscosity allows for easier handling and manipulation of the chocolate, ensuring efficient and consistent production. Here is an example.

During the tempering process, chocolate is heated and cooled to specific temperatures to ensure the cocoa butter in the chocolate crystallizes properly. Properly tempered chocolate has a glossy appearance, a smooth texture, and a snap when broken.

Now if the viscosity of the chocolate is too low or runny, it becomes challenging to handle and manipulate. The chocolate may flow excessively, making it difficult to control during pouring, molding, or coating.

It may spread too thinly when poured into molds, resulting in uneven or fragile chocolate shapes. Similarly, when coating items like truffles or nuts, the thin chocolate may not adhere properly, resulting in inconsistent coatings.

On the other hand, if the viscosity of the chocolate is too high or thick, it becomes stiff and less fluid. This can impede the flow of chocolate during production processes. It may be challenging to pour the chocolate into molds or spread it evenly during coating. This can lead to irregular shapes, uneven coatings, and an overall unappealing appearance of the final product.

By incorporation PGPR during the manufacturing, the viscosity is controlled. Hence, the chocolate flows smoothly and consistently. This results in consistently shaped chocolates, uniform coatings, and an aesthetically pleasing final product. A 2013 study determined a 0.5% lecithin and 0.1% PGPR is best for viscosity and yield point for chocolates.

Emulsification

The main reason why PGPR is added to chocolate is because of its emulsification property.

We know that water and oil are two liquids that do not mix well, right? Well, ingredients in chocolate are no different.

Chocolate is a complex mixture of fat (cocoa butter) and water-based ingredients (sugar, cocoa solids, milk solids, etc.). These components have different polarities and do not naturally mix well. Without an emulsifier, the fat and water phases in chocolate would separate, resulting in an unstable and unappealing product. This is where PGPR functions.

PGPR’s emulsification effectiveness is attributed to its molecular structure, which provides a balance between hydrophilic and hydrophobic characteristics. This allows it to interact with both fat and water components, facilitating their dispersion and creating a stable emulsion.

PGPR works by reducing the surface tension between the fat (cocoa butter) and water phases in chocolate. The molecule contains hydrophilic (water-loving) polyglycerol chains and hydrophobic (fat-loving) polyricinoleate chains. When added to chocolate, PGPR orients itself at the interface between the fat and water phases. The hydrophilic polyglycerol chains of PGPR interact with the water molecules present in the chocolate, while the hydrophobic polyricinoleate chains interact with the cocoa butter, which is the main fat component. This dual interaction helps to create a stable and uniform emulsion.

This results in a homogenous mixture.

Preventing fat bloom

Preventing fat bloom is a secondary effect of PGPR’s emulsification properties. Fat bloom occurs when chocolate is exposed to temperature fluctuations, causing the cocoa butter to migrate to the surface, resulting in a whitish or grayish discoloration.

When chocolate is heated, the cocoa butter melts, resulting in fat bloom. As the fat melts, it uses capillary action to travel and migrate through the chocolate structure’s microscopic channels and gaps. This movement of melted fat inside the chocolate matrix can result in an uneven distribution of fat, giving rise to fat bloom.

Once the temperature decreases, the melted cocoa butter begins to solidify again. However, since the fat has moved and settled on the surface due to its migration, it recrystallizes there. The recrystallized fat forms a separate layer on the surface, giving the chocolate a whitish or grayish appearance.

By introducing PGPR into chocolate, the risk of fat bloom is reduced since it improves fat dispersion inside the product. This is accomplished by decreasing the surface tension of the fat and other chocolate ingredients. As a result, cocoa butter can diffuse more uniformly throughout the chocolate, lowering the possibility of fat migration and subsequent bloom production. Although PGPR is important in minimizing fat bloom, other factors such as storage conditions, temperature variations, and the specific chocolate formulation can all have an impact on the occurrence of bloom.

This blog post discusses more about fat bloom.

SAFETY OF PGPR TO HUMAN HEALTH

Many consumers are wary about the safety of food additives, especially if they seem more “chemical” than natural. And PGPR is no exception. PGPR is a synthetic compound, which can lead to skepticism about its safety compared to natural ingredients. However, it’s crucial to remember that not all synthetic substances are automatically harmful, and that includes PGPR.

And here’s why.

PGPR is approved for use as a food additive by regulatory agencies worldwide, including the U.S. Food and Drug Administration (FDA), the European Food Safety Authority (EFSA), and other relevant authorities.

These agencies have reviewed the scientific evidence on PGPR and determined that it can be used safely in food products. To investigate the safety of PGPR, numerous toxicological studies have been undertaken. These studies looked into potential side effects such as acute toxicity, genotoxicity, carcinogenicity, and reproductive toxicity.

In one study, the carcinogenic potential of PGPR was assessed in rats and mice. For 80 weeks, 25 male and 25 female mice were fed diets containing 5% PGPR or groundnut oil. There was no evidence that PGPR causes cancer. PGPR also had no deleterious effects on growth, food intake, lifespan, or blood health.

Studies involving human subjects

During the mid 1960s, a study of PGPR involving human subjects was conducted. PGPR was consumed at levels up to 10g/day for 2 weeks. The study found no consistent adverse effects on various biochemical parameters, as well as no toxic effects on the liver and kidneys. These results indicate that the consumption of PGPR, even at higher quantities than typically consumed, does not have adverse effects on human health.

Consistent findings from various studies support the conclusion that PGPR does not present substantial risks to human health when consumed within approved limits. Regulatory bodies such as the FDA and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) have established the Acceptable Daily Intake (ADI) for PGPR at 7 mg/kg body weight per day. In Europe, the European Food Safety Authority (EFSA) has set a higher ADI for PGPR at 25 mg/kg body weight per day. The ADI represents the maximum amount that can be safely consumed daily over a lifetime without causing adverse effects.

CONCLUSION

In conclusion, polyglycerol polyricinoleate (PGPR) is a food emulsifier derived from the seeds of the castor oil plant. It plays a crucial role in chocolate production by effectively binding cocoa solids and cocoa butter together, creating a smooth and creamy texture. PGPR controls viscosity, ensuring the chocolate flows smoothly during various production steps. It also acts as an emulsifier, preventing the separation of fat and water-based ingredients in chocolate, resulting in a stable and uniform emulsion. Moreover, PGPR helps reduce the likelihood of fat bloom, which can occur due to temperature fluctuations.

Regarding safety, regulatory agencies such as the FDA and EFSA have deemed PGPR safe for consumption within approved limits. Studies involving human subjects have found no adverse effects on health even at higher consumption levels. The ADI for PGPR has been established to ensure its safe use in food products.

Overall, PGPR is a valuable ingredient in chocolate manufacturing, contributing to its texture, stability, and overall quality.

The post What Is Polyglycerol Polyricinoleate (PGPR) In Chocolate? appeared first on The Food Untold.

Emulsifiers are used as a key ingredient in ice cream. As a food additive, they hold several functions, depending on the food. Generally, they help increase food palatability, increase food volume and aeration, decrease stickiness, improve food flavor, enhance food textural properties, and impart foam stability.

In ice cream, emulsifiers helps the ice whip more readily. The ice cream also becomes dryer, has better melting resistance, is smoother, and has a better texture. In some ice cream, emulsifiers also destabilize the milk protein in the final ice cream product to improve its structure. Because of their relatively higher surface activity and ability to form liquid crystal metaphases, emulsifiers in ice creams tend to promote protein desorption from the surface of fat droplets. Emulsifiers serve as nucleation sites for triglyceride surface crystallization. They also aid in the formation and stabilization of ice cream foam prior to partial fat globule coalescence and freezing.

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Traditional emulsifiers for ice cream production include egg yolks. They contain lecithin, a natural emulsifier that aids in uniting the molecules of fat and water to produce a creamy and smooth texture. Egg yolks are a common ingredient in custard-based recipes because they give ice cream a richness and depth of flavor.

Today, there are many emulsifiers that can be used for ice cream making. Aside from lecithin from egg yolks, mono-/diglycerides, and polysorbates are commonly used. These emulsifiers are often used as blends.

Let’s discuss them briefly.

HOW EMULSIFIERS WORK IN ICE CREAM

Emulsifiers have a unique chemistry. They have molecules with two ends, one of which is drawn to water and the other to fat. The water-loving end of an emulsifier’s molecule surrounds the water droplets in an ice cream mixture, while the molecule’s fat-loving end surrounds the fat droplets. Small emulsion droplets are produced as a result, which the emulsifiers stabilize and disperse throughout the mixture.

The emulsified fat droplets are broken down into smaller pieces as the ice cream mixture is frozen and churned, giving it a smooth and creamy texture. Without emulsifiers, the ice cream’s fat would collect into lumps, giving it a grainy or lumpy texture. Additionally, emulsifiers aid in preventing the growth of large ice crystals, which can cause the ice cream to separate.

In order for emulsifiers to function properly, the aging must be adequate. During this stage of production, emulsifiers adsorb to the surface of the fat droplets, and partially replace the milk proteins. The emulsifiers start to crystallize as the mix cools. This makes them more hydrophobic. Thus, they adsorb more onto the fat droplets. When the ice cream mix is frozen, it is challenging to incorporate and stabilize air bubbles without them. This is especially true in the industrial setting. The nature of the mix and the intended use determine the aging time, which in turn determines the degree of fat crystallization and emulsifier adsorption.

Aging of mixtures of extruded products for at least 6 hours causes greater partial coalescence. This usually results in a stiffer ice cream. For most types of ice cream products, two hours of aging is sufficient. In factories, it is convenient to age a mixture over night and store it in aging tanks prior to production. Ideally, it should not be kept for more than three days.

EGG YOLK

Egg yolk contains several components that make it a great functional ingredient in food manufacturing.

But in ice cream making, lecithin is the most important as it contributes the most to egg yolk’s emulsifying abilities. The approximate weight percentages of the components of an egg yolk are: 50% water, 16% protein, 9% lecithin, 23% other fat, 0.3% carbohydrate, and 1.7% minerals. Lecithin is made up of phospholipids and phosphatides. It is frequently utilized in premium, homemade, or “all-natural” ice creams

Lecithin does its job by combining the molecules of fat and water to produce a creamy, smooth texture. Without it, ice cream mix can become icy or grainy. Additionally, lecithin aids in stabilizing the ice cream, preventing it from melting too quickly or freezing up too hard. It can aid in lowering overrun (the amount of air whipped and incorporated into the ice cream) of the product.

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Egg yolk is typically supplied for use in the production of ice cream in one of three forms: pasteurized fresh egg yolk, frozen pasteurized sugared egg yolk, or dehydrated egg yolk. Normal usage levels of egg yolk solids range from 0.5% to 3%. Frozen pasteurized sugared egg yolk often contains 10% sucrose to prevent damage during freezing. Super-premium ice cream products may contain high concentration to give ice cream an eggy flavor.

MONO-/DIGLYCERIDES

Mono- and diglycerides are emulsifiers that are made up of a glycerol molecule and one or two fatty acid molecules attached to it. Mono- and diglycerides are lipids or fats that are soluble in both fat and water. This unique property enables them to function as emulsifiers, assisting in the combination and stabilization of fat and water-based ingredients in food products such as ice cream.

Due to the hydrophilic nature of the glycerol end and the hydrophobic nature of the fatty acid end, mono- and diglycerides are surface active. The fatty acids in mono- and diglycerides determine their characteristics, just like they do for triglycerides. Vegetable fats like soybean oil and palm oil that have undergone partial hydrolysis are used to create mono- and diglycerides. They typically contain diglyceride, a small amount of triglyceride, and monoglyceride in amounts ranging from 40% to 60%.

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Ice cream production frequently uses fully saturated mono-/diglycerides that primarily contain stearic and palmitic acids. An example of this is glycerol monostearate, which typically makes up about 0.3% of the ice cream mix. This is ideal for low fat ice cream since it provides smooth texture and body similar to regular ice cream.

POLYSORBATES

As opposed to mono- and diglycerides, polysorbate types of emulsifiers are known to be more effective at displacing proteins from the oil-water interface, making them better emulsifiers for ice cream. However, the mono- and diglycerides have better foaming properties, which means they can create more initial foam before the fat droplets clump together at the air-water interface.

Monoglycerides and sorbitan esters of fatty acids share structural similarities. Polyoxyethylene sorbitan monooleate, commonly called polysorbate 80, is present in many products in a reasonable amount, keeping the ice cream scoopable. Instead of glycerol, polysorbate 80 has a fatty acid attached to a sorbitol molecule. The sorbitol molecule also has polyoxyethylene groups attached to it, making it water soluble. When used as an ice cream emulsifier, polysorbate 80 can be used at concentrations of 0.02% to 0.04%. Like most food additives, polysorbates are safe to consume in moderation, and are subject to regulation by food safety authorities.

References:

M. Wallert, K. Colabroy, B. Kelly, J. Provost (2016). The Science of Cooking: Understanding The Biology And Chemistry Behind Food And Cooking. John Wiley & Sons, Inc..

Chris Clarke (2004). The Science of Ice Cream: RSC (2nd edition). RSC Publishing.

P. Cheung, B. Mehta (2015). Handbook of Food Chemistry. Springer

T. Msagati (2013). Chemistry of Food Additives and Preservatives. John Wiley & Sons, Ltd.

The post Emulsifiers Used In Ice Cream appeared first on The Food Untold.

Emulsifiers are one of many additives that are used extensively in the food manufacturing industry. But what exactly are emulsifiers, really? Would food product that usually contain them be exactly the same without them? Well, basically, emulsifiers are food additives that produce and maintain an emulsion. And an emulsion is a mixture or two or more liquids that normally do not mix together.

To better explain what exactly an emulsion is, let’s have oil and water as an example. These two liquids are not miscible—they do not form a homogeneous mixture. Even if we try to mix them, the water molecules will only attract with each other and the oil molecules will stick together. And since water molecules pack closer together, the oil will only find itself sitting on top of the water. This is where emulsifiers come in. They work to stabilize emulsions to keep the liquids from separating. They do this by breaking up either the water or oil phase into small droplets that remain dispersed throughout the other liquid.

Common emulsion is oil and water in salad dressings, shortenings, margarine, and ice cream. How do emulsifiers exactly work?

Let’s discuss further.

HOW EMULSIFIERS WORK

Emulsifiers are a part of a group called surfactants or surface active agents, which also include foaming agents, detergents, and dispersants. They mainly help lower the tension between two phases of matter to achieve a certain goal. Detergents, for example, enable water molecules to spread more easily, allowing it to clean dirt from the surface. In the case of emulsifiers, they decrease the tension between two liquids.

While oil and water are immiscible, emulsifiers keep them from separating. They are able to achieve this because they contain both a hydrophobic molecular end and a hydrophilic end. A hydrophobic molecule repels water, but are attracted to oil (“oil loving”). Whereas a a hydrophilic molecule has a tendency to dissolve in and mix with water (“water-loving”). The presence of both types of molecules allows an emulsifier to act as a binding agent between oil and water. This, in return, produces a homogeneous emulsion. Generally, emulsions have minimal stability. However, surface active agents and other similar substances can help enhance their stability.

Liquids or emulsions in food can be oil-in-water (mayonnaise) or water-in-oil. An example of a water-in-oil emulsion is margarine. The continuous phase or the surrounding liquid here is oil, while the dispersed phase is water, which is in the form of small droplets. Without an emulsifier, instead of water dispersing in oil, it will separate to form layers of oil and water. And that is not what a margarine should look like, right?

Emulsifiers also have other functions in food. They are able to form complexes with other food components. One good example of this is the amylose-complexing effect of emulsifiers. This effect is beneficial for improving the shelf life of baked products (anti-firming effect) and modifying the physical properties of starchy foods such as potatoes and pasta.

FACTORS THAT AFFECT EMULSION STABILITY

One of the many challenges that the research and development of the food industry face is how the ingredients would interact with each other. This is especially true once they undergo processing or storing. Here are the factors that affect emulsion stability.

Emulsifier

There is no wonder why the type of emulsifier itself is the main factor that affects emulsion stability. Basically, emulsifiers that produce stable interfacial films also produce stable emulsions. There must be also an adequate concentration of emulsifier in order to coat the surface of all the droplets.

Droplet size

Speaking of droplets, their size also affects emulsion stability. Large droplets tend to coalesce, where two or more droplets merge during contact. Moreover, oil and water have a significant density difference—water is more dense (heavier) than oil. So oil floats above the water. But large oil droplets rise through the emulsion more easily, creating a stronger emulsion closer to the surface. This will eventually cause the emulsion to break.

Ph and ionic strength

pH or acidity also affects emulsion stability. By changing the pH by adding acid, it may reduce the stability of the interfacial fil,. Adding salts changes the ionic strength (concentration of ions), which may also reduce the stability of the interfacial film.

Viscosity

The viscosity of the emulsion also affects stability. The thicker the emulsion, the slower the molecules move within the system. Hence, the longer it will take for the two phases to separate. One common way to modify the viscosity is the addition of a thickener such as pectin, gums, or gelatin. The addition of gums in salad dressings may already form a permanent emulsion without the need for an emulsifier such as egg yolk.

It is worth noting that gums are added as stabilizing agents, not as emulsifiers because they are hydrophilic. But their ability to increase the viscosity of the system helps reduce the number of collisions between droplets. This slows down or prevents separation of emulsions.

Storage and handling

During storage or handling, some emulsions can also be affected negatively. Emulsions are delicate systems since they contain immiscible liquids. Hence, improper handling can cause breakage of the emulsion.

Temperature

Another factor that affects emulsion stability is temperature. Generally, temperature affects the properties of water, oil, as well as interfacial films, and surfactant solubilities. In a warm temperature, oil droplets become more fluid. And coalescence is more likely to occur. These reduces the stability of emulsions.

Refrigeration temperatures, on the other hand, solidify oil droplets, enhancing emulsion stability. However, freezing temperatures are not ideal for most emulsions. The reason for this is that emulsions do not survive freezing temperatures. Proteins at the interface become denatured at freezing. Furthermore, ice crystals that form tend to rupture the interfacial film. Before being subjected to freezing, emulsions are often added with gums to enhance their stability.

A FEW COMMON APPLICATIONS OF EMULSIFIERS IN FOOD

The oldest emulsifier known to man is beeswax. It was when the Greeks first used it as an emulsifier in cosmetic products. Then in the early 19th century, food manufacturers started using egg yolk, the first emulsifier to be used in food. Egg yolk owes most of its emulsifying capability to its phospholipid lecithin content. Lecithin is an amphiphilic fatty substance—able to attract both water and fat. While an effective emulsifier, egg yolk has a rather short-term stability.

For this reason, food manufacturers had to find a better alternative to egg yolk. They found it in the form of lecithin derived from soybeans.

However, the most significant development came in the 1930s with the introduction of mono- and di-glycerides of fatty acids. Initially used in margarine, these synthetic emulsifiers later extended its uses, which include ice cream and baked products such as breads and cakes. Other synthetic emulsifiers were later introduced for use commercially in the late 20th century. Today, common emulsifiers include mono- and diglycerides of fatty acid, guar gum, carageenan, and polysorbates. Here are some of their common food applications.

Ice cream

Ice cream is a mixture of solids, partially frozen milk fat and ice; liquid, unfrozen cream and water; and gas, pockets of air trapped in freezing mixture. All these three phases form a colloid. But ice cream is not only an emulsion, but a foam as well. And it contains ice crystals and unfrozen aqueous phase, whose freezing point is depressed by freeze concentration sugars, salts, and polysaccharide stabilizers.

The incorporation of emulsifiers in ice cream produces a product that whips more easily, has a smoother body and texture, is drier, has better meltdown resistance during consumption, and with minimized shrinkage during storage.

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Common emulsifiers in ice cream production are polysorbates (E432, E436), and mono and diglycerides (E471). The reason for this is their relative abilities as emulsion destabilizers, or as foam-forming agents. Polysorbates are better at displacing protein from the oil/water interface than mono and diglycerides. And therefore are better emulsion destabilizer. Mono and diglycerides, on the other hand, are better foaming agents, hence aid in the formation of the initial foam prior to fat-droplet agglomeration at the air/water interface. Other emulsifiers used in ice cream include lactic acid esters (E472b), lecithin (E322) and propylene glycol esters (E477).

Baked products

According to a 1996 study, bakery products are the largest users of emulsifier. The bakery industry accounts for 50% of the food emulsifiers market. Emulsifiers have multiple functions in baked products. But unlike in other food products, emulsification of oil in water is of secondary importance. Perhaps, emulsifiers hold more value in protein strengthening, starch complexing, and aeration.

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Shortening is one of the key ingredients in baking. When added and mixed into a hydrated dough, it interrupts in the development of the gluten network. Or the structure is “shortened”, to simply put. This produces a product that is tender, has rich flavor and uniform aeration. Common shortenings include margarine, butter, margarine, and lard. Adding an emulsifier to the shortening promotes the emulsification of the shortening in the batter or dough.

Emulsifiers used in breads and buns include lecithin, diacetyl tartaric acid esters of monoglycerides (DATEM), polysorbate 60, calcium stearoyl lactylate (CSL), sodium stearoyl lactylate (SSL), and mono and di-glycerides. Among these, monoglycerides in their many forms are the most used emulsifiers in baked products, especially yeast-baked products, as well as icings, cakes, and other applications. Cakes with monoglyceride-containing shortening have better aeration and sugar holding capacity. Monoglycerides also retard staling rate, improving the shelf life of breads.

Infant nutritional products

These types of products are specially formulated for infants as well as young children. They come several forms: concentrated liquid, ready-to-feed liquid, and powder reconstituted for consumption. A stable oil-in-water emulsion is an important step in the manufacture of these products. Normally, this is achieved by thorough homogenizing the oil phase in an aqueous phase, which consists mainly of carbohydrates, proteins, vitamins, and minerals. The oil phase usually consists of a blend of vegetable oils that include coconut, palm, sunflower, and soybean oil. The formation of a stable oil-in-water emulsion is a common prerequisite of both liquid and powder processes.

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In liquid products and products produced by the wet-mixing/spray drying system, a fluid fat blend is dispersed and emulsified in an aqueous system, which contains carbohydrates, proteins, minerals, and emulsifiers. In the case of dry blended formula, the fat has already been emulsified within a system, usually one more more protein sources.

The emulsifier ingredients in infant nutritional products can be classified into two: the protein and non-protein emulsifiers. Bovine milk proteins are very common in infant nutritional products. Other protein emulsifiers include demineralized whey, milk protein isolate, soy protein isolate, and calcium caseinate. The non-protein emulsifiers are low molecular weight surfactants. Common protein emulsifiers in infant nutritional products include lecithin, mono and di-glycerides, sucrose esters of fatty acids, citric acid esters of mono and di-glycerides of fatty acids, and starch sodium octenyl succinate.

Chocolates and sugar confectionery products

Emulsifiers in chocolates and sugar confectionery products provide several functions during processing and storage. In caramel, toffee, and other confectionery products that contain a disperse fat phase, emulsifiers help break down the fat into small well-dispersed fat globules.

In bubble and chewing gums, stabilizers work as plasticizers of the gum base, making the base more pliable to the mouth. They also provide water retention hydration during chewing. Common emulsifiers in gums include lecithin, glycerol monostearate, and acetylated monoglycerides. If lecithin is used, up to 1% can be used to soften chewing gums. To aid in dispersion, vegetable oil or suitable fatty emulsifiers can be added.

In chocolates, lecithin and polyglycerol polyricinoleate (E476) are the most common emulsifiers. These emulsifiers provide several beneficial effects in chocolates. However, for the most part, they provide control over flow properties in chocolates. This allows chocolates to be molded into various shapes (bars, chips, etc.).

Another emulsifier used in chocolates is sorbitan tristearate (E492). It helps delay and prevent the formation of fat bloom in chocolates. Fat bloom is discussed in more detail here. Fat bloom forms because of the appearance of fat crystals that emanate from the surface. It is characterized by the whitish coating or gray haze at the surface. Fat bloom can occur for several reasons. First, the improper processing conditions such as bad tempering and incorrect cooling method. Second, the composition of the product. And lastly, the storage condition.

Processed meats

Processed meats are meats that have been modified in order to improve its quality (taste and appearance) and shelf life stability. The processed meat segment is a huge business. In the United States alone, processed meat comprises one third of the meat industry. The processed meat segment is even bigger in Europe, where sausages are the most popular type of processed meat. Within the region, the Czechs, Germans, and Austrians consume the most sausages per capita. The basic ingredients in sausages include ground meat (pork, beef, chicken), fat, and water. An emulsifier holds these components together, forming a stable emulsion.

Citric acid esters (E472c) in bolognas, wieners, frankfurters, wieners, and hotdogs offer good dispersibility in the meat batter. Mono and di-glycerides of fatty acids also enhances the binding effects in meats. Meat batters are a type oil-in-water emulsion. The disperse phase consists of liquid or solid fat particles while the continuous phase is the water, which contains the dissolves salts and suspended proteins.

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In order to ensure the uniform distribution and consistency of the emulsion, a stabilizer can be added. Common stabilizers in meat products include guar gum, cellolose gum, and locust bean gum. These stabilizers also provided additional benefits; they prevent fat migration during storage, help retain moisture, and provide viscosity control during processing.

Other references:

Chen and  A. Rosenthal (2015). Modifying Food Texture. Woodhead Publishing

G. Hasenhuettl and R. Hartel (2008). Food Emulsifiers and Their Applications (2nd edition). Springer

 V. Vaclavik and E. Christian (2014). Essentials of Food Science (4th edition). Springer

J. deMan, J. Finley, W. Jeffrey Hurst, Chang Yong Lee (2018). Principles of Food Chemistry (4th edition). Springer

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