Emulsifiers: Getting right the oil-water relationship in foods

As consumers demand more greek yogurt on their dinner and breakfast tables, manufacturers will have to innovate around latest trends in the segment to make their products stand out from the crowd.

The immiscibility of oil and water has inspired the proverb “oil and water don’t mix” and other expressions that reflect the general incompatibility of two entities.

Surprisingly, a good portion of the food we eat such as mayonnaise, milk, salad dressings, to name but a few, are comprised of water and oil components that are uniformly distributed. This interaction between immiscible liquids is called an emulsion and is made possible by compounds known as emulsifiers.

Simple emulsions are either oil suspended in water (o/w), or water suspended in oil (w/o). Milk is an example of an o/w emulsion, in which the fat phase or cream forms tiny droplets within the skim milk, or water phase. In contrast, margarine is a w/o emulsion containing droplets of water or skim milk in a blend of vegetable oils and fat.

In both cases, emulsifiers are needed to prevent the suspended droplets from coalescing and breaking the emulsion. Apart from stabilizing an emulsion, emulsifiers also make the finished product soft and smooth in texture. In some applications such as ice cream processing, the addition of emulsions leads to better dispersion, solubilization, crystal modification, foaming and creaming ability.

It would therefore be safe to say that without emulsifiers, some of the foods that we currently have from ice creams to chocolates and even sausages would not have existed or if they did, not in the quality and taste that we enjoy today.

How emulsifiers work  

Emulsifiers have a unique attribute of having both a hydrophilic (water-loving, or polar) head group and a hydrophobic (oil-loving, or nonpolar) tail. This makes them attracted to both polar and nonpolar compounds. 

When added to an o/w emulsion, emulsifiers surround the oil droplet with their nonpolar tails extending into the oil, and their polar head groups facing the water. For a w/o emulsion, the emulsifier’s orientation is reversed: nonpolar tails extend outward into the oil phase, while polar head groups point into the water droplet. In this way, emulsifiers lower the interfacial tension between the oil and water phases, stabilizing the droplets and preventing them from coalescing.

The type of emulsifier used depends on the application, with cationic emulsifiers typically used in low-to-neutral pH solutions and anionic emulsifiers in alkaline solutions.

However, not all emulsifiers are the same. Some are cationic (positively charged polar head group), while others are anionic (negatively charged head group), or non-ionic (uncharged head group). The type of emulsifier used depends on the application, with cationic emulsifiers typically used in low-to-neutral pH solutions and anionic emulsifiers in alkaline solutions. Non-ionic emulsifiers can be used alone or in combination with charged emulsifiers to increase emulsion stability.

Common food emulsifiers  

For centuries, cooks have added natural emulsifiers, such as egg yolk, mustard, or honey, to create stable emulsions. Today, a wide variety of nature-based and synthetic emulsifiers are available for different food applications from bakery to meat processing.

Of all emulsifiers currently in use today, lecithin is arguably the most popular. The compound, which is a blend of naturally occurring phospholipids, is widely used in the food industry to promote o/w emulsions. Commercial bakers especially find lecithin useful in preventing the split of water and oil particles. By keeping the droplets of oil in water safe, lecithin also increases the stability and shelf life of the food. 

Fatty Acid Derivatives are the second most common class of emulsifiers, with several emulsifiers derived from fatty acids including polyglycerol esters (PGE), polysorbates, stearoyl lactylates, propylene glycol esters (PGMS), and sucrose esters.

PGE is commonly used in desserts like cakes and their icings while PGMS is preferred for toppings that are whippable. Sucrose esters are on the other hand useful in products like gums, coffee, and sauces.

A different class of emulsifiers known as polyglycerol polyricinoleate (PGPR) is common in the chocolate industry. It works well in enhancing the thickness and volume of the product. Chocolate coatings flow satisfactorily when PGPR is added unto its mixture, making it a helpful agent in maintaining the good quality of the chocolate or other products that require certain smoothness and viscosity.  

Sunflower-based Ammonium phosphatide (AMP) has been the most triumphant emulsifier in chocolate and confectionery manufacturing. It is chiefly efficacious in achieving uniformity and steadiness of the mixture, leading to high-quality food products. Chocolate manufacturers also say it does pretty well in helping them achieve the right size, texture, smell, and thickness.  

Mono and Diglycerides class wraps up our small list of common emulsifiers used in the food industry today. They are produced when palatable oils are blended with glycerin and are used in a number of food applications, from chocolates processing to the making of baked and dairy products. Monoglycerides work well in foams that are whippable while managing the agglomeration of fats. For products like chocolates, they give the sensation that feels like the food product is melting inside your mouth – adding the to the taste and feel of the food. 

Choosing the right emulsifier  

With a wide variety of emulsifiers existing in the market, choosing the right emulsifier for a particular food application can be challenging.

Calculating the hydrophilic-lipophilic balance (HLB) of an emulsifier or combination of emulsifiers can be a good place to start. Different emulsifiers have different HLB values, which in theory, can be used to predict their ability to stabilize various kinds of emulsions.

HLB scale ranges from 0 to 20, with 10 corresponding to an emulsifier that is equally attracted to water and oil. Emulsifiers with HLB values greater than 10 are more hydrophilic and thus better at stabilizing o/w emulsions. In contrast, emulsifiers with HLB values less than 10 are more hydrophobic and therefore better suited for w/o emulsions.  

John Neddersen Senior Application Scientist, Fats and Oils, Emulsifiers at IFF notes that knowing an emulsifier’s HLB is not satisfactory enough as “foods are complex systems with many different ingredients interacting.” To get the right emulsifier for your food application, Neddersen advises practical experimentation in food application labs.  “Although guidelines like the HLB scale can help, most of the time experience and experimentation are needed to find the optimal choice of emulsifiers and usage rates,” he advises. This is where emulsifier providers like IFF, Palsgaard, Bunge and Kerry come in to help food processors choose the right emulsifier for their foods. 

IFF for instance sells a broad range of emulsifiers, including the Panodan® DATEM (diacetyl tartaric acid ester of monoglycerides) line especially for bakery products and the Cremodan® line for ice creams and other frozen desserts. As an alternative to lecithin in chocolates and other confectionary, IFF offers Grindsted® CITREM, a citric acid ester. This emulsifier can substitute for soy lecithin, which has recently come under fire, particularly in Europe, because most soy crops grown for export are genetically modified.   

Palsgaard, on the other hand, boasts of a wide range of emulsifiers for use in different kinds of applications from chocolate and cakes to condiments and meats.  For baking, the emulsifier expert offers several solutions for different cake applications. Its Emulpals® 115 emulsifier is for instance good in making better-for-you cakes while its Palsgaard® SA 6615 comes in handy for industrial bakers seeking to avoid using palm oil in their product mixes. If you want to make a low-fat or a fat-reduced mayonnaise, Palsgaard has a solution to help you achieve this goal. For those seeking to control stability in plant-based beverages Palsgaard offers RecMilk 131, a combination of mono- and diglycerides, and stabilisers – which work together to provide a pleasant and creamy consistency while at the same time reducing separation during storage.

Embedding sustainability into emulsifiers

Emulsifiers being key in many food applications has not escaped the scrutiny of many environmentally conscious consumers.

Palm oil, a key ingredient in making many emulsifiers, has been associated with deforestation of some of the world’s most biodiverse forests. Calls for its complete elimination from food chains has led to suppliers such as Palsgaard coming up with a new class of non-palm emulsifiers that give manufacturers more ways to address consumer concerns. Where palm oil emulsifiers cannot be replaced, the company also offers a full product range made from palm oil that is 100% Roundtable on Sustainable Palm Oil (RSPO) certified, sustainable and segregated. US-based IFF has also committed to only using palm oil from sustainable sources to allay consumer concerns about the commodity. 

Clean label affects emulsifier formulations

Today, consumers fear foods comprised of long lists of ingredients that they cannot identify, preferring clean-label foods which are comprised of leaner lists of ingredients they know. 

“Before they choose a cake, many consumers now look carefully at the recipe,” Christophe Lequet, Senior Application Specialist, Palsgaard A/S says. “If they see a long list of ingredients they don’t recognise, they’re put off, so the fewer E-numbers the better.”

To meet this demand, emulsifier providers have had to create new solutions with less ingredients. Palsgaard has for instance created the Palsgaard® SA 6610 for cakes which only has one E-number, a great improvement when compared to the six or seven E-numbers that are usually in cake gel alternatives. Sternchemie also recently released SternPur S DH 50 – a hydrolyzed, de-oiled sunflower lecithin suitable for powdered ingredients, baked goods and beverages. This new solution within the SternPur range is allergen-free and non-GMO. The company says that SternPur S DH 50 is the ideal alternative to artificial emulsifiers which can taint a product’s clean-label status. 

Emulsifier use beyond food applications

For centuries, emulsifiers have been predominantly used in food and today, their use has spread to other fields including medicine, nutraceuticals, home and personal care, and even in packaging.

Emulsifiers have particularly come in handy in the production of food-grade plastic packaging and film. Their incorporation enhances the anti-static performance of the packages while also improving their anti-fogging capabilities. This, according to Palsgaard, offers a new way of keeping food and its packaging fresh and appealing. 

Practical experimentation  

Basically, advances in technology have allowed manufacturers to create emulsifiers tailored for specific food applications.

Today, we have emulsifiers specifically tailored for the production of activated cakes while others are best suited for mayonnaise production. Food technologists have even come up with emulsifiers to suit modern day trends from clean-label to better for you and plant-based foods. No two emulsifiers are however the same. What would work well in cakes might turn out to be a bad option for chocolate or yogurt production.

To find out which is the best for your food application, Neddersen’s advises practical experimentation. Working closely with your emulsifier supplier is therefore key in identifying the right emulsifier for your food.  There is always something for everyone, you just  have to find what perfectly suits your needs.

This feature appeared in the Sep/Oct 2021 issue of Food Business Africa. You can read this and the entire magazine HERE