3/6/2023 0 Comments Milk emulsionIn the kitchen, this may entail vigorous beating or whisking by hand or by a mixer. Making small droplets requires adding energy to create a large interfacial area. Some ingredients can affect viscosity densities are usually pretty well fixed so droplet size becomes the one processing variable that can be manipulated.Įmulsification involves making small droplets and having them adequately coated with the appropriate emulsifier. In addition to emulsifiers, other factors that affect the stability of emulsions include the viscosity of the continuous phase (higher is better), the droplet size (smaller is better, typically 1–10 μm), and the difference in densities between the two phases (smaller difference is better). Unfortunately, in that use, the nondigestible fat replacers are said to have some unpleasant effects on one’s digestive system. Sucrose esters have been used as fat replacers, including in frying of snacks, to reduce calories. Emulsifiers in cake batter promote better release of cake from pans. In chocolate, emulsifiers reduce viscosity, permitting a reduction in the amount of cocoa butter, which reduces both cost and calories. For example, stearoyl lactylates and mono- and di-glycerides can retard staling in baked goods by interfering with starch retrogradation. The same chemicals that are good emulsifiers are often used in other ways in foods. They have different properties depending on which specific fatty acids are included. The mono- and di-glycerides are food emulsifiers made by transesterification followed by molecular distillation. Other common emulsifiers found in foods include proteins, gums, and various esters of fatty acids and poly hydroxyl substrates, such as lactic acid, sucrose, and polysorbates. Values of 7– 9 indicate good wetting agents. An HLB less than 6 favors water in oil emulsions a value greater than 8 favors oil in water emulsions. Heating risks irreversibly denaturing the egg yolk (think scrambled eggs) and so must be carefully controlled.Įmulsifiers are characterized by their hydrophilic lipophilic balance (HLB), a number from 1 to 20 that indicates which tendency is more dominant. Mayonnaise is normally made at room temperature because the oil phase is usually vegetable oil, but other sauces may require mild heating because the oil phase is often butter, which is solid at room temperature. Egg yolk is the traditional emulsifier for mayonnaise and other culinary sauces, but because of its dual functionality, these products can be tricky to make successfully. Egg yolk contains two emulsifiers-lecithin, which promotes oil in water emulsions, and cholesterol, which promotes water in oil emulsions. It is an effective and popular food emulsifier. Lecithin is a phospholipid molecule found in soy and isolated in refining of soy oil. There are both natural and synthetic emulsifiers. The oil-attracting, lipophilic end is often a long-chain hydrocarbon region such as a fatty acid. The water-attracting portion often is ionic and is described as hydrophilic. Emulsifiers form physical barriers to prevent droplets from coming together.įood emulsifiers have much in common with detergents in that both classes of chemicals have water-loving and oil-loving (or attracting) regions on the same molecule. The driving force for coalescence is the reduction of interfacial area, which reduces the thermodynamic energy level of the system. Most emulsions require the use of functional chemicals, called emulsifiers, to stabilize the suspension of small droplets and prevent them from coalescing or coming together to grow larger droplets. Other food emulsions include mayonnaise, salad dressings, and sauces such as Béarnaise and Hollandaise. Familiar foods illustrate examples: milk is an oil in water emulsion margarine is a water in oil emulsion and ice cream is an oil and air in water emulsion with solid ice particles as well. There also can be more complex systems, such as oil in water in oil (o/w/o). Common emulsions can be oil suspended in water or aqueous phase (o/w) or water suspended in oil (w/o). An emulsion is a temporarily stable mixture of immiscible fluids, such as oil and water, achieved by finely dividing one phase into very small droplets.
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