When Oil And Water Don’t Mix
Wednesday, September 13th, 2017 | 612 Views
Emulsifiers and stabilisers are commonly used food additives for their functional properties. What roles do they play in food applications? By DPO International
Emulsifiers and stabilisers have a large range of beneficial and functional properties when applied properly to food formulations of a variety of food categories such as bakery, cakes, or even ice cream. Also known as food additives, they are substances that maintain the physicochemical state of a food product.
This means that they help to assure consistency in food textures and prevent vital ingredients from separating in certain food products such as dairy products and low-fat spreads. A common use for these food additives is in reduced-fat or low-fat food products, or that which requires the mixing of ingredients that normally do not mix such as oil and water.
In a nutshell, emulsifiers particularly help in the mixing of ingredients that would normally separate, while stabilisers prevent them from separating again.
Emulsifiers are fat-like substances that can be found naturally in both animal as well as vegetable fats and oils. Structurally, they are molecules with one hydrophilic (water-loving) and one hydrophobic (oil-loving) end, that binds to water and oil and makes it possible for the two liquids to become finely dispersed in each other. Examples of emulsifiers include lecithin and monoglycerides, and can be found in soya bean or eggs and the latter in lard.
As early as the early 19th century, egg yolk was used as an emulsifier in food applications. However, due to the short shelf life of egg yolk-based products, lecithin, which could last longer, was derived from soya bean and used instead.
Initially used only in margarine production, the use of emulsifiers soon extended to cake and bread applications as well, and the food industry saw an exponential increase in natural and synthetic emulsifiers being produced and used from the second half of the 20th century.
Emulsifiers are useful in food applications as they provide stable mixtures such as in salad dressings or margarine without compromising on taste or shelf life, and can also contribute to soft yet non-crumbly bread.
Stabilisers play an important role in upholding the texture and mouthfeel of food, and work with emulsifiers to maintain the homogenous dispersion of two or more immiscible substances in a food product. They also include substances which stabilise, retain or intensify the existing colour of the food product.
Added in a relatively small amount to aggravate the effect of emulsifiers, the polysaccharide-based stabilisers increase viscosity in food products to give them a uniform nature, and help hold the fl avouring compounds in dispersion.
Common stabilisers include agar, cellulose, gelatin, or various gums such as guar gum, Arabic gum or xanthan gum. Stabilisers are crucial in applications for ice cream, margarine, spreads and dairy products.
The use of two or three component emulsifiers and stabiliser blends to achieve multiple functionalities is a common practice within the food industry for the various effects on the production processes of various types of food.
Bakery Products And Cakes
Stabilisers and emulsifiers have multifunctional properties when used in bakery products as they also help to improve the quality and shelf life of bread products (e.g. buns, loaves and pastries). The effects of emulsifiers in bakeries are focused on starch and gluten proteins. Emulsifiers have an important role in baked goods as they improve loaf volume, and this is due to their chemical structure that can interact with all substances, influencing the staling process.
In dough, emulsifiers have a positive effect on proof time, loaf volume and crumb firmness. This might be related to their ability to bind to the protein hydrophobic surface, promoting aggregation of gluten proteins in dough.
In bakery fillings, stabilisers prevent water migration from the filling to the pastry again due to its water-binding properties. Besides, stabilisers appear to inhibit starch retrogradation and improve freeze-thaw stability of frozen dough, extending shelf life of finished products. Incorporation of stabilisers and emulsifiers in bread formulation has great value in improving the overall quality of bread-making.
Emulsifiers also play an important role in cake manufacturing as it helps to improve the batter stabilisation. The introduction of an emulsifying agent into a shortening enhances its emulsifying properties, making the cake batter to have a higher viscosity and greater stability. The air becomes more finely distributed within the cake resulting in a larger yet more moist cake.
Stabilisers such as carrageenan are used to strengthen and extend protein ingredients in cake mixes. They also aid air entrapment, thus improving cake volume. Cake mixes that incorporate stabilisers show better moisture retention and a softer texture in the final product compared to those that do without them in their product formulations.
Chocolate And Confectionery
Emulsifiers are used in both chocolate and sugar confectionery products as functional additives because of the significant advantages they provide during both processing and storage.
For products containing a dispersed fat phase, emulsifiers help to promote the breakdown into small fat globules. They also provide lubrication for ease in processing and consumption. Emulsifiers provide viscosity control and influence fat crystallisation in chocolate and coating. It also improves the ease of handling and processability.
Stabilisers and emulsifiers have proved their effectiveness in formulating functional dairy products. They are used in dairy products and fermented milk drinks to prevent protein from aggregating and dehydrating as well as improve the emulsion stability throughout the entire shelf life.
Various types and blends of stabilisers and emulsifiers improve the mouthfeel and creaminess of end products. They also help to improve the appearance, body, texture and consistency of food products.
Stabilisers and emulsifiers help to formulate high-rheology products, such as yogurt and flavoured milk of excellent texture and body, appearance, consistency and mouthfeel.
Margarine And Spreads
Margarine manufacturing involves balancing the hydrophobic emulsifiers needed for processing and their hydrophilic emulsifiers contributing to good eating qualities.
Emulsifiers are used to give fine disperse and stable water and oil emulsions in margarine. Stabilisation of low calorie spread emulsions and use of the right emulsifier is very important for achieving a stable spread.
Low-fat margarine exhibits higher water content than 80 percent margarine, which sets special demands on the emulsifier system and processing. The emulsifier used should be able to bind large amounts of water in order to obtain a stable product with longer shelf life. Also, the addition of emulsifiers in products such as peanut butter can help inhibit oil phase separation.
Stabilisers have an important role in water-binding capacity and sensory properties in margarine and spreads applications. Various mixtures of stabilisers offering margarine produce a great variety of stabiliser systems by binding free moistures. The incorporation of stabilisers not only results in creamier, easy-to-use product, it also protects unsaturated oil from oxidation, thereby extending shelf life.
The thickening or gelling effect of stabilisers and emulsifiers contribute to body and texture in ice cream application. They influence texture and mouthfeel and can be used to control the distribution of particles in a solution.
Stabilisers have a high water-binding capacity and they can affect rheological properties of an ice cream mix. Incorporation of stabilisers in ice cream formulation leads to an increase in viscosity which has important effect on the melting behaviour of the product.
Emulsifiers are used in ice cream because they contribute greatly to a smooth and creamy texture by promoting fat destabilisation. Emulsifiers help to destabilise fat globule membranes during homogenisation. They thereby promote partial churning-out of milk fat during freezing.
Both stabilisers and emulsifiers will remain vital to food processors, especially to those who use recipes of ingredients that involve fat or oil and water. However, with the increasing consumer awareness and demand for healthier food products, it is also essential that food manufacturers meet these demands with their stabilisers and emulsifiers.
To date, more and more stabilisers and emulsifiers are being made more natural, as well as having a clean label. Food producers will likely continue to use stabilisers and emulsifiers for years to come, as they are vital in imparting and maintaining a desired consistency in finished food products.
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