Posts Tagged lecithin

Emulsifiers in food

Ice cream is another food that would not exist were it not for emulsifiers.

Oil and water don’t mix but they do form emulsions – and these are crucial to the consistency of a number of foodstuffs. Nature is good at making emulsions, and the classic example is milk, where a complex mixture of fat droplets are suspended in an aqueous solution.

Emulsifiers are the chemicals that make emulsions happen. Nature uses proteins and phospholipids, and many emulsifiers used in modern food production are based on these natural substances.

Ice cream is another food that would not exist were it not for emulsifiers.An emulsifier is a molecule in which one end likes to be in an oily environment and the other in a water environment. To make an oil-in-water emulsion, such as mayonnaise, droplets of oil molecules are surrounded by the oil-loving end of the emulsifier molecules. This leaves the water-loving ends on the outside of the droplet, and so they sit happily in water, giving a homogeneous liquid rather than an unappealing mixture of water and oily droplets. In mayonnaise, the emulsifier is the phospholipids present in egg yolks – they are such successful emulsifiers that as much as 80% oil can be dispersed in the aqueous phase.

Ice cream is another food that would not exist were it not for emulsifiers. It is both a foam and an emulsion, and its texture results from the ice crystals and unfrozen water it contains. But it’s not just creamy products where emulsifiers are crucial – bread and other baked products, where solid particles are dispersed in an airy foam, are enhanced by emulsifiers.

The emulsifiers that are used commercially come from both natural and synthetic sources. They include:

Lecithins (E322) are mixtures of phospholipids such as phosphatidyl choline and phosphatidylethanolamine, and are usually extracted from sources such as egg yolk and soybeans. The precise composition of the phospholipids depends on the source. Uses include salad dressings, baked goods and chocolate.

Esters of monoglycerides of fatty acids (E472a-f) are made from natural fatty acids, glycerol and an organic acid such as acetic, citric, lactic or tartaric. The fatty acids are usually from a vegetable source, though animal fats can be used. Products that use them include ice cream, cakes and crisps.

Mono- and diglycerides of fatty acids (E471) are semi-synthetic emulsifiers made from glycerol and natural fatty acids, which can be from either plant or animal sources. They are used in products like breads, cakes and margarines.

Chemist in the kitchen


A page from our first website!

If you want to know more about how food additives tie in with the chemistry that goes on in the kitchen, a downloadable booklet entitled ‘In the mix’ is accessible from the home page, or from the image on this page.

Chemicals have always been welcome in the kitchen: sodium bicarbonate, pectin, yeast, acetic acid etc.

Every cook is a chemist. The first chemical laboratories, back in the Middle Ages, were glorified kitchens, and many chemical processes derive from techniques of cooking. The vital technique of distillation was perfected in the course of man’s search for intoxicating drinks. And far from being dehumanizing, such chemical processes have an ancient magic and glamour, as the great Italian writer Primo Levi pointed out (he was also a chemist):-

Distilling is beautiful.

‘First of all, because it is a slow, philosophic, and silent occupation, which keeps you busy but gives you time to think of other things, somewhat like riding a bike. Then because it involves a metamorphosis from liquid to invisible (vapour) invisible, and from this once again to liquid; but in this double journey, up and down, purity is obtained, an ambiguous and fascinating condition, which starts with chemistry and goes very far. And finally, when you set about distilling, you acquire the consciousness of repeating a ritual consecrated by centuries, almost a religious act, in which from imperfect material you obtain the essence, the usia, the spirit, and in the first place alcohol, which gladdens the spirit and warms the heart.’

Every kitchen contains a battery of chemical reagents, each with their specific chemical purpose; e.g. sodium bicarbonate, pectin, yeast, acetic acid, sodium chloride; and also substances, such as milk and eggs, that are not usually thought of as chemicals but which actually miracle reagents that chemists would still be incapable of creating if they didn’t already exist.

In many cases, ingredients that sound like chemicals are derived from natural products: lecithin from soya is similar to egg lecithin, acetic acid comes from vinegar, Vitamin C is the active ingredient of lemon juice, and so on. The principle of using additives is something that every cook, high or low, uses every time they prepare a meal. To understand the processes of making sauces, meringues, bread and cakes, of marinading, tenderising and caramelising is to become a food chemist, and it greatly enhances the pleasure of cooking to see it from a chemical point of view. Cooking is chemistry in action, with the added benefit that you can eat the results.