Introduction
An emulsion is a combination of two immiscible liquids such as oil and water, which when broken down into finer particles these immiscible liquids combine without separating from each other. Emulsions occur naturally in food, one such example is milk where the milk fat is dispersed in the aqueous medium. A food emulsifier is an additive which acts as a surface active agent between two immiscible liquids and releases the surface tension between the two liquids and helps them to become stable and inseparable.
Emulsions are of two types:
1. Oil in water emulsion: In this type of emulsion the oil is dispersed in the aqueous phase. An example of this type of emulsion is mayonnaise.
2. Water in oil emulsion: In this type of emulsion the aqueous phase is dispersed in the oil. An example of this type of emulsion is margarine.
Advances in food technology sector have led to the development of many synthetically prepared emulsifiers which help in improving the texture, shelf life and flavour of the food products.
Emulsifiers used in Margarine
Margarine is a fat spread and is used in preparing various types of bakery products and confectionaries. Margarine is water in oil type of emulsion, where the aqueous phase is dispersed in oil. The uniformity and size of the water droplets depend upon the type of emulsifiers used. Monoglycerides containing high molecular fatty acids in combination with soy lecithin is usually used as an emulsifier in margarine.
Depending on the purpose of use margarine are of three types, solid, soft and liquid margarine. Solid margarine is mostly used in bakery and confectioneries and is stable at room temperature. Soft margarine is mainly used in household cooking and catering. Liquid margarine is mainly used for frying in fast food restaurants. Since liquid margarine has high water content in it a process called splashing may occur, due to the melting of margarine the emulsion is broken. To prevent splashing in liquid margarine, citric acid esters and monoglycerides in combination with soy lecithin provides stable water dispersion. A concentration of 0.4-0.5% of monoglyceride is used to form stable emulsions in margarine.
| Type of margarine |
Dose
by% weight |
| Table margarine |
0.25-0.4% |
| Margarine with a low fat content |
0.5-0.7% |
| Liquid margarine |
2% |
| Margarine for puff products |
0.70% |
| Cream margarine |
1.0-1.5% |
Emulsifiers in Ice Cream
Ice cream is oil in water kind of emulsion where the oil is dispersed in the aqueous phase. Emulsifying agents such as mono/diglycerides are used mostly in the preparation of a very low fat ice cream. Polysorbate 80 is also used as an emulsifier in ice cream at a concentration of 0.1-0.2%. Egg yolk is also used as an emulsifying agent in ice cream as egg yolk contains lecithin which helps in emulsification. Egg yolks are used mostly in solid powder form in the concentration range between 0.5-3%.
Emulsifiers in Bread
Emulsifiers are used in bread to improve the dough strength, reducing the proofing time, improve the crumb structure and thickness and also for improving the shelf life of bread. The most commonly used emulsifiers used for strengthening the dough are diacetyl tartaric acid ester of monoglycerides (DATEM), Sodium stearoyl lactylate (concentration 0.5%) and polysorbate 60 (concentration 0.5%) which also improve the crumb texture in bread. Emulsifiers such as lecithin and enriched lecithins have shown a significant anti-staling effect on the bread in 2 hours of proofing time (M. Gomez et.al. July 2004).
Emulsifiers in Chocolates
Chocolate is a combination of cocoa solids, sugar and milk solids which are dispersed in cocoa butter. A mixture of all the solids in the cocoa butter together clumps up and does not give chocolates a smooth texture. Addition of emulsifiers in chocolate improves the texture and sensory attributes as well. Lecithin is the most widely used emulsifier in chocolates. Lecithin consists of 50-60% weight of phospholipids. The most commonly used forms of lecithin are liquid and powdered form. As a substitute to lecithin ammonium phosphatides are used as they are cheaper than lecithin. Ammonium phosphatides decrease the viscosity in chocolates to give chocolates a smoother texture. Sorbitan tristearate is used in chocolate to prevent fat bloom which is undesirable in chocolates.
Emulsifiers in Processed Meats
Processed meats include Frankfurters, Bologna, chicken nuggets, sausages, salami and surimi, which are processed by the addition of few additives such as nitrites and nitrates and are smoked or cured to prevent spoilage. Emulsifiers are used in meat to bind the meat protein, fat and water together in a stable emulsion and to provide the right texture to the meat. Processed meat is oil in water type of emulsion where the oil is dispersed in the aqueous phase. The myofibrillar protein in the meat act as an emulsifier. Actomyosin and myosin in the meat help in emulsification of meat after the meat are chopped finely as they are amphiphillic and protein in nature. Emulsifiers not only improve the texture of meat but also improve the taste.
There are natural as well as synthetic emulsifiers available. The isolation of natural emulsifiers and using it for emulsifying food will be a healthier alternative rather than using the synthetic ones. Natural emulsifiers include phospholipids, proteins and polysaccharides can be used instead of synthetic emulsifiers. Emulsifiers are known to improve product quality and texture and are frequently used in many food products.
(The author is quality executive at Candor Foods Pvt. Ltd, Navi Mumbai. She can be contacted at joshnajoseph162@gmail.com)