Food Emulsifier Application
Emulsifiers have various effects on the production process of food and improve its quality. They are used in various types of food. Functions of emulsifiers are listed below.
Bread and sweet rolls sold at super-markets and convenience stores are usually mass-produced. Mass production and mass distribution require time and speed from start to finish.
Emulsifiers are used to maintain the softness as long as possible and to make bread dough suitable for machine production.
Emulsifiers are not only used for emulsification, but also for dough modification, that is, dough gets tolerable against mechanical force by modulating the proteins in wheat flour.
Bread is made by mixing and kneading flour, water, salt and yeast, and baking the dough following fermentation.
Wheat flour contains 10-14% protein and 1-2% lipid along with starch. 80% of protein is gluten, from which gluten membrane is produced during mixing.
Air bubbles are created during mixing, and the gas produced by fermentation expands during baking to fill the space under the gluten membrane. The force due to these gases causes a rising of dough.
At a temperature over 60°C, starch rapidly expands following
water absorption, leading to gelatinization.
With a further increase in temperature, the inner phase is made up with denaturation of protein gluten membrane. If this phase is insufficient, gas leaks out and bread expanding does not occur.
A small amount of lipid contained in wheat flour is said to mediate the formation of gluten membrane. The emulsifier is thought to have similar effects.
Major effects of emulsifiers on bread production are as follows;
- To make a less-sticky and elastic dough that is easy to handle.
- To increase the dough resistance to mechanical force to soften and create easy raising.
- To make smooth bread of good eating quality, and to maintain the softness.
Noodles, Instant Mashed Potatoes
Emulsifiers make a rigid complex with starch to protect starch granules and improve the quality of starchy foods.
NoodlesEffects of emulsifiers on macaroni, spaghetti of low water content, fresh noodles containing high water content and dried instant noodles are different, however, the basic effects on starch are similar.
For macaroni and spaghetti, emulsifiers provide elasticity and smooth uniform surface which prevents sticking after boiling.
In fresh noodles, emulsifiers make easy-to-handle dough and increase the water absorption rate by 1-2%. The surface of noodles becomes smooth, uniform, and less sticky, which improve and streamline the production process.
In instant noodles, emulsifiers improve absorption and decrease cooking time.
Instant Mashed PotatoesThe process to make mashed potato are boiling, mashing and drying into flakes.
If a starch granule is broken or damaged in this process, amylose in the starch granule is apt to dissolve, resulting in a sticky and glutinous product.
When distilled monoglyceride is added just before drying, it forms a starch complex, which protects starch granules. Thus, the mashed potatoes exhibit a smooth texture.
Cakes are classified on the basis of the compounding ratio of fat to flour as shown in the following table.
Oils and Fats Content Ranging
|10-50%||Butter Sponge Cake|
Sponge cake is made by utilizing the foaming ability of eggs.
Butter sponge cake is made by further additions of butter and margarine.
On the other hand butter cake is produced from a batter foamed after the addition of large amount of butter or margarine.
Sponge and butter sponge cake are basically made from sugar batter method. Sugar is added to whole eggs after foaming and combined
The use of emulsifier makes it possible to produce an all in one-mixture method, in which all materials are mixed at the same time and foamed.
As for the production method for butter cake, there are two methods;
sugar batter method, in which foaming is carried out after the addition
of sugar to the lipids, and flour batter method, in which flour
is added to the lipids before foaming however all-in-one mixture-method
becomes possible only by the use of a foaming agent.
The roles of emulsifiers in production of cakes are as follows.
For sponge cake, fine stable foam are obtainable with it.
For butter sponge cake of high fat content or butter cake, emulsifiers control the anti-foaming effects of lipids and keep stable foaming.
- Uniform quality products can be continuously produced.
- Big volume, well-balanced products with smooth-surface are obtainable.
- Soft products with homogeneous inner phase are obtainable.
|Kinds of Cakes||Wheat
|Dorayaki (Bean-Jam Pancakes)||100||70||50||˜||˜|
|Butter Sponge Cake||100||120||150||25||˜|
|White Butter Cake||100||100||80||40||30|
Concerning the manufacturing process of ice cream, a liquid form mixture of raw materials is prepared and homogenized by a high pressure homogenizer. After short period of high-temperature sterilization, the homogenate is stabilized by letting it stand sit for several hours at a temperature below 5℃.
Soft cream is produced by foaming in a freezer at -2 to -9°C, and pouring into a small container followed by rapid freezing.
Oils and fats, ones of the major components of ice cream, form fat balls by emulsification, and their surfaces are covered with emulsifiers and are coated with milk-like protein like casein. By combining with an emulsifier, the fat balls become fine and stable.
Homogeneous fat balls present in ice cream, start to associate in
a row during aging, and aggregate like a bunch of grapes. Then,
fat balls densely adsorbed on air bubbles surface to make fat ball
Then, a part of fat balls become unstable and the ball surface is broken, resulting in oil droplet aggregations, growth of ice crystals and destruction of the foam.
These conditions are called de-emulsification. It is said that these components produced by moderate de-emulsification can be mixed with the foams which is surrounded by stable fat balls to make a skeleton like structure.
As the degree of de-emulsification varies with the amount of fat used and the kind of emulsifier, it is necessary to select an appropriate combination.
The effects of addition of an emulsifier are:
- The progress of uniform fat emulsification is stimulated.
- Stable overrun is obtainable.
- An emulsifier participates in the formation of a dry and firm structure of ice cream leading to smooth texture.
- Heat shock resistance is obtainable.
- Shape keeping ability is enhanced.
Fresh cream is ordinarily prepared by concentrating milk fat to 18% or more through centrifugation of raw milk.
- Skilled techniques are needed to foam cream because the quality of fresh cream greatly varies with given feed and seasons.
- The foamed fresh cream is unstable and difficult to decorate and easily defoams.
Imitation cream was developed by adding non-fat milk solid component, emulsifier and stabilizer to vegetable oil, and it rapidly spread nationwide because of its two characteristics which are pure white color and light flavor.
Furthermore, a compound cream having the advantages of both fresh cream and imitation cream, has been put on the market. Recently, good quality compound cream has become a major product.
Cream is a typical product of O/W emulsion.
Representative cream products are coffee whitener and whipped topping. The fat content of coffee whitener is low because the emulsion is more easily broken as coffee is an acidic solutions and usually served at high temperature.
Requirements for coffee whitener are:
- High dispersibility
- Non oil-separable
- Non feathering by aggregation of milk protein
- Whitening effects
Both emulsification and de-emulsification effects are needed for an emulsifier
of whipped Topping.
Emulsifier helps the formation of coating membrane from the protein complex on the emulsification of whipped topping so as to make a strong coating membrane sufficiently resistant to high temperature sterilization and cooling.
The strongly-stabilized fat balls adsorb on the surface of air bubbles to make a network, resulting in the stabilization of foam.
And de-emulsification creates the skeleton like structure of cream by coagulating oil drops in the emulsion and affects taste and shape retention.
Accordingly, it is necessary to investigate the properties and the amount of the emulsifier to be used.
It is said that tofu was introduced from China and the basic manufacturing method has not been changed since.Foam Extinguisher
- Anti-foaming effects
- Defoaming effects
Increased Protein Content in Soybean Milk
To make cotton tofu, GO has to be created first by grinding with ten times more amount of water than that of soybeans right after soaking soybeans in water. GO is to be separated into soymilk and bean-curd(okara) lees after boiling, modifying protein and filtration.
After cooling, a coagulating agent is added to soybean milk and the mixture is poured into a box covered with a cloth. The aqueous part called "Lyu", is removed by weight-loading. The remains are molded.
Silken tofu is produced by making a concentrated soybean milk with about 5 times the amount of water and standing alone for coagulation.
Production flow for Tofu
Cotton Tofu (Momen Tofu)
Silken Tofu (Kinugoshi Tofu)
When GO is steamed, its vigorous bubbling occurs in the presence of protein and saponin of soybean by boiling. In a continuous steaming system, the bubbling lowers the heat conductivity, resulting in non-uniformity. Also, numerous bubbles are produced during the separation of bean-curd lees, and the bubbles left in the soybean milk weaken the structure of tofu. Tofu has been produced in the cottage industry and foam extinguisher oil was used as an anti-foam agent. Recently, however, monoglyceride is widely used because of a large scaled manufacturing and spread of hygienic concerns among the public.
Foam extinguisher for tofu has anti-foaming effects to repress
foaming as well as defoaming effects.
Generally, a distilled monoglyceride of saturated fatty acid is added to "GO" to repress foaming.
Other than the anti-foaming effect, monoglyceride stimulates emulsification of "GO", and makes a complex with starch which inhibits swelling, resulting in improved separation of bean-curd lees and increased protein content in the soybean milk.
Margarine and Shortening
Margarine, produced by emulsifying milk with lipids, was born in 1869 in France
as a substitute for butter.
Some problems with margarine are; separating water droplets and spattering during cooking. Since the 1920s, monoglycerides and lecithin have been used so exclude these defaults.
Margarine and shortening are the representatives of processed oils a fats. Margarine and low calorie spreads are used in food such as bread, cake, pie, Danish pastry and butter cream, for both household and industrial uses. In addition, there are various functional oils and fats such as fats for fresh and ice creams, powdered fats and releasing oil. For the development of a new processed fat product, it is important to know how to use emulsifiers effectively.
The effects of emulsifiers on processed oils and fats are;
- Emulsification in production process and stabilization of the product.
- Enhancement of spreading effects of oils and fats on bread or pie base.
- Improvement of foaming and air-holding abilities and creaminess.
- Improvement of water retaining ability.
- Improvement of the functions of starch and protein.
- Prevention of spattering during cooking, etc.
In addition to these, emulsifiers have many others function due to the effects on crystal forms of oils and fats as follows.
Prevention of Crystallization
The process to fractionate a liquid fat from solid oil by temperature
control is called wintering.
Winterized salad oil is a clear liquid, which occasionally changes to a turbid one with time, owing to crystallization. This change is prevented by adding a specific emulsifier.
An emulsifier of which solubility in fats and oils is low, deposits as crystals together with fats of low melting point, but these crystals are very fine so that the solution appears to be clear.
Inhibition of Crystal Growth
When a once-melted chocolate solidifies again, a rough surface of fine
powders may be produced. This condition is called blooming.
It is attributed to the high crystalline nature of cacao fats, of which triglycerides have comparatively uniform structure. Blooming is also prevented by adding a specific emulsifier.
This is caused by the inhibition of crystal growth, which occurs when an emulsifier with a quite different structure is introduced to cacao fats, which have a simple structure.
Acceleration of Crystal GrowthSolid fat produced while wintering is removed by filtration. The larger crystals in solid fat are, of course, easily removed by filtration.
It is said that when a specific emulsifier is present in the wintering process, the emulsifier functions as a core of the crystal, resulting in the formation of large crystal.
Improve the Plasticity of Fats and Oils
The requirement of processed oils and fats is plasticity regardless
of temperatures as seen in margarine which spread easily, even at
low temperatures and dose not melt at high temperature.
Margarine of which hardness is less variable with temperature was once produced using acetylated monoglycerides or saturated monoglyceride, the crystalline conformation of which holds as a liquid oil.
Soft margarine contains much liquid oil, however, it retains its structure by forming abundant crystals of solid fats. An emulsifier improves the shape keeping capacity of soft margarine by the formation of these abundant crystals of solid fat.
Improvement of Creaming Texture of Fats and Oils
The creamy property enabled through aeration during the mixing process
is important for confectionery. Fats and oils used in such items
as butter cream and biscuits, are affected by crystal forms of fats
Monoglyceride, especially unsaturated monoglyceride like safflower and sunflower monoglyceride, has strong effects on improving creaminess.
Increase Water-Holding Ability of Fats and Oils
Plastic fats and oils have a water-holding ability, but emulsifiers further enhance it.
When increasing amount of emulsifier, holding water ability rises. When an emulsifier is added at 5%, 1 to 2-fold amounts of water can be held. Especially for monoglyceride, when the unsaturation degree is high, the holding-water rate is high. When safflowers and sunflower monoglyceride is added at 10%, water can be held over 5-fold.
In this case, W/O emulsion is formed. Unsaturated monoglycerides specially produce strong, liquid crystal gel at room temperature, which appears to protect the water drops.
Fats and oils for butter cream and icing to be combined with large amounts of syrup are an example of such monoglycerides.