Friday, February 10, 2012: 04:11:29 PM


The Right Blend of Emulsifiers

Roy Silva delves into the use of emulsifiers in the Indian food processing industry

Commercially produced foods are multiphase systems made by automated processes. These foods have a large distribution network, and are stored for extended periods before reaching the consumer. These factors make an emulsifier a critical ingredient in food formulations. As the Indian food industry continues to be industrialised, the importance of emulsifiers has become more pronounced.

The basic function of an emulsifier is to stabilise an emulsion, a dispersion of two or more immiscible liquids. A dispersion of oil in water is a classic example. An emulsifier has a water loving-hydrophilic-end and an oil lovinglipophilic- end. This means, when it is added in small quantities to the oil-water mixture during the mixing process, the lipophilic end of the emulsifier will submerge in the oil fraction, and the hydrophilic end will submerge in the water forming a film round the oil droplets to help stabilise the dispersion of the oil in the water. Emulsifiers play a critical role in processed meat, which is a fat-watermeat emulsion.

Decoding an Emulsifier
This is the basic concept on which food emulsions such as salad dressings are prepared. Since the functionality of emulsifiers depends on their surface activity, they are also identified as surfactants. Egg yolk was the first emulsifier to be used in food production. The emulsifying component in egg yolk is lecithin—a combination of various phospholipids. Phospholipids are emulsifiers which are developed from a combination of glycerol, fatty acids and phosphoric acid. Soy lecithin is cheaper and a by-product in the extraction of oil from soybeans, and has found growing popularity with the growth of the natural concept.

Soy lecithin is also extensively used in chocolate and margarine production. To optimise and standardise the functionality, tailor-made chemical emulsifiers were developed that were derived from fats. When a fatty acid like stearic acid combines with an alcohol like glycerol, the resultant product is an ester. The first ester used as an emulsifier was Glyceryl MonoStearate (GMS).

At first, commercial GMS contained both a monoglyceride (functional) and a diglyceride (nonfunctional) component. Molecular distilled monoglyceride was obtained through a distillation process whereby the mono was gradually increased from 40 percent to 90 percent. This improved GMS has the ability to form a complex with starch and is the principal surfactant used in retarding the staling of bread. Bread baked by the local baker is eaten fresh each day and the problem of staling is not critical. With growing awareness of foodfreshness, bread that is at least a day or two old when the consumer gets it, has to have GMS added to it to extend its shelf life.

GMS was chemically modified to an ethoxylated monoglyceride to improve proteincomplex properties, and function as a dough conditioner to improve bread volume. Succinylated monoglyceride is another derivative. While emulsifiers are used in the full range of the food industry, the baking industry has been a primary user and has fuelled product development in emulsifiers. Derivative emulsifiers have been developed using monoglyceride combined with organic acids. It has the ability to stabilise emulsions and was added to cake batters to produce high ratio cakes.

The Molecular Equation
Modern food processes are complex and often need multifunctional emulsifiers. Some of the important functions of food emulsifiers include:

• Emulsion stabilisation
• Aeration and foam stability
• Complexing with water, moisture and viscosity control
• Complexing with starch to promote shelf life and texture
• Complex with proteins to optimise rheology of wheat doughs
• Complexing with fat to promote or inhibit crystallisation such as for chocolate and margarines.

Di-acetyl tartaric acid ester (DATEM) is an emulsifier with a superior potential for protein complexing. DATEM is used as a dough conditioner in bread dough. Acetylated monoglycerides are used in fat agglomeration and in aeration of whipped toppings. New emulsifiers have also been synthesised by direct esterification of fatty acids with alcohol. Sodium stearyl lactylate (SSL) was formed by combining organic acids—stearic and lactic— with sodium to give a powerful protein complexer and dough conditioner in bread production.

Propylene glycol mono esters (PGME) are formed by direct combination of propylene glycol with fatty acids. PGME is used widely in cake and sweet formulations. Sorbitan esters are prepared by combining sorbitol with fatty acids. They have a range of uses including aeration of icings and control of crystallisation in fats. Polysorbates are derived from sorbitan esters and used in a wide range of icings and whipped toppings.

Sucrose esters are developed by combining sucrose with fatty acids—palmitic and stearic acid—from palm oil. They have the ability to control protein denaturation in heat and also find use in coffee whiteners. They are also used in pasta and noodles to prevent sticking and in ice cream to optimise freeze-thaw stability. Polyglycerol Esters (PGE) are developed by first creating a polyglycerol and then combining it with a fatty acid. PGE has a wide range of functionality, besides being used in cake batters for aeration, in margarine to reduce spattering and in salad oils for crystal inhibition. Most importantly PGE functions as a fat mimetic and may be used in reduced fat products.

The Emerging Emulsifier Market
Commercial emulsifiers were initially used in a powder form. As food products and processes became more complex, emulsifiers were produced as blends of two or more to give multi-functionality. As a next step and with an understanding of its crystalline forms, emulsifiers are now used in a paste form. With the growing automation of the food industry, the latest demand is for pump-able emulsifiers. There has been a steady demand for better quality ‘natural’ emulsifiers. Traditional commercial emulsifier products are available in the beta form since this is a very stable state, but has moderate to good functionality. The alpha crystalline form is the most functional but has stability problems. Technologists have now developed alpha stable-blended emulsifier gels with superior functionality. Emulsifiers have also been optimised by modifying the crystalline state. Fat-based emulsifiers exist in four different crystalline forms.

Frozen meals and desserts have a substantial market in the West and emulsifiers play a critical role in freeze-thaw stability. With this trend increasing in Asia, there will be a demand for customised emulsifiers. The continuing demand for low-fat food products has boosted the market for emulsifiers. Fat reduction results in food products that have reduced eating quality and shelf life, and emulsifiers like PGE that can replace fat functionality at comparatively lower use levels. Low fat dairy products are emulsifiers that can contribute organoleptic properties typically provided by fats.

Milk and eggs are ingredients commonly used in food formulation. But with a view to reduce costs, cheaper replacements are being developed, with emulsifiers being critical in contributing functionality. Emulsions can also be stabilised by emulsifiers which are not lipidbased esters. Proteins are made up of hydrophobic amino acids that have surface active potential. Milk is a natural emulsion of fat in water. Milk proteins act as an emulsifier to coat the oil droplets and stabilise the emulsion. Whey proteins help disperse fat in sauces and soups, and also modify viscosity to give a creamy mouthfeel. Gums and gelatins stabilise emulsions by increasing the viscosity of the water phase and help keep the oil in a stable dispersion.

Soon enzymes and hydrocolloid gums may replace some emulsifiers. It is possible that customised blends with emulsifiers and either enzymes and/or gums may be a multifunctional option. Technological advancements in the food processing industry continue to boost the demand for new multifunctional emulsifiers. Combined with the market demand for low fat and the general focus on healthier food products, there will continue to be a substantial demand for a range of emulsifiers.

Roy Silva is Technical Consultant, Product Development and Technical Marketing, USA.

Rate me....
Mail this article Mail this article Print this article Print this article

Contribute/ Share your Opinion



Magazine Issues


logo Other Times Group Sites: