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 baked goods and chocolate.
One of the most common emulsifiers in the biscuit industry is Soya Lecithin, as an emulsifier it promotes water in oil emulsions, as it helps keep oils with incompatible specific gravities from separating.
Soya Lecithin acts as a dough conditioner by negating the effects of strong wheat glutens.
- The reduction of stickiness in a dough
- More efficient use of shortening-dispersion
- Improved baked colour in low fat recipes
- Greater stability with regard to the impeding of the onset of rancidity
Soya Lecithin, a good antioxidant was found to survive baking and an addition of 0.15% was found to increase shelf-life.
It has been used in all of the above applications, but ‘tailor-made’ emulsifiers have been proven to be more effective.
DEFINITION OF AN EMULSIFIER
Surface active agents are chemical materials which alter the surface properties of the material they contact.
They orientate themselves along the interface of two adjacent surfaces reducing the resistance of the two substances to combine.
An emulsion is basically the dispersion of small droplets of one insoluble liquid within another liquid.
Synthetic emulsifiers are derived from a polyol and a fatty acid or fat. The polyols most commonly used are glycerine, propylene glycol and sorbitol. The fats and fatty acids can be derived from various animal and vegetable sources.
Emulsifiers can be classified as either ionic or non-ionic, based on their tendency to ionize in an aqueous solution. The major disadvantage of ionic emulsifiers in the food industry is that they are pH sensitive and may react with other food components to form complexes which may affect their emulsifying strengths.
Emulsifiers act as an interface between the conflicting components of food like water and oil. Each component of food (carbohydrate, protein, oil and fat, water, air, etc.) has its own properties which are sometimes conflicting to one another just like oil and water. To make the two components compatible, emulsifiers are used.
An emulsifier is a molecule with one oil-friendly and one water-friendly end. Water friendly end in food emulsifier is called hydrophilic tail and oil-friendly end is called hydrophobic head.
Food emulsifiers are also called emulgents.
In this way droplets of oil are surrounded by the emulsifier molecule, with the oil core hidden by the water-friendly tails of the emulsifier.
A classic natural emulsion is milk, which is a complex mixture of fat suspended in an aqueous solution. Nature's emulsifiers are proteins and phospholipids (lipids means fat soluble phosphate is water soluble).
Egg is commonly used as an emulsifier.
Some emulsifiers also act as anti-caking agents like Magnesium Stearate, Sodium, potassium and calcium salts of fatty acids.
Few others like Sorbitan monostearate are emulsifier as well as stabiliser.
Types of Food Emulsifiers
- Egg Yolk emulsifying agent lecithin
- Soya lecithin
- CSL Calcium Stearoyl Di Laciate
- PolyGlycerol Ester (PGE)
- Sorbitan Ester (SOE)
- PG Ester (PGME)
- Sugar Ester (SE)
- Monoglyceride (MG)
- Acetylated Monoglyceride (AMG)
- Lactylated Monoglyceride (LMG)
They may be derived from the natural products or chemicals.
Common emulsifiers are lecithins, mono- and di-glycerides of fatty acids esters of monoglycerides of fatty acids and phosphated monoglycerides.
The emulsifiers that are used commercially come from both natural and synthetic sources. They include:
- 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.
- 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.
EFFECT OF LEVEL OF G. M. S. IN CAKE PROCESSING
As the level of G.M.S. is increased the cake specific volume decreases, crumb firmness increses and cell structure becomes finer.
Effect of batter Specific Gravity
The use of Emulsifiers in a Fat Sparing Excersise
Admul Data and Artodan
Bakery emulsifiers can help you to achieve batter stability, improved cake volume and texture, prolonged shelf life and cost reductions.
Aeration, crystallization, fat reduction and plastification: control these four basic properties and you can optimise your process
Work was carried out by F.M.B.R.A. They proved that Admul Data at 0.75% of fat weight gave good results in hard sweet biscuits with 15-20% fat reduction and with 20% fat reduction in Lincoln Biscuits
An emulsion is a mixture of two immiscible liquids in a colloidal dispersion, or one being present in the other in the form of droplets
The classic emulsions of oil and water are the two main types: oil-in-water, in which the oil represents the dispersed phase or internal phase and water the constant phase. The second is water-in-oil in which the phases are reversed.
Emulsifiers can be supplied as a Powder, (that requires Hydration, before application) or as a Suspension/ Emulsion. The latter is often used, but degenerates over time, contributing to incremental dosage rates being used to compensate for this deficiency.
Each supplier has their own method of maintaining stability by their process methods.
Emulsifiers are often used to extend the properties of the fat, or to allow a reduction in fat, as was experienced in ‘low-fat’ cookies / biscuits.
The emulsifiers , also known as surfactants, help stabilise the emulsion by lowering the interfacial tensions between water and oil.
In the absence of an emulsifier mixtures of immiscible liquids are unstable, with the two liquids tending to separate into two layers.
Emulsifiers partition themselves at the interface between oil and water.
The water dispersed in oil type emulsions which is found in butter and margarine has different properties.
It may interact with other components such as protein and starch.
I am a great advocate of Mechanical Emulsification, during the Mixing Process (creating a suspension of water and fat or oil) which will produce a homogenous dough, with uniform distribution of the fat/water phase within the dough
By this method it not only improves the processing of biscuit dough through the gauge rolls, but minimise the tendency for ‘checking’ due to the uniform distribution of the water within the dough, reducing the stress factors as water is randomly oscillating as its movement is restricted as it migrates to achieve an equilibrium with the baked biscuit / cracker