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EMULSIFIERS by Mind Map: EMULSIFIERS
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EMULSIFIERS

Emulsifiers are substances which reduce the surface tension at the interface of two normally immisicble phases, allowing them to mix and form an emulsion. Emulsifiers belong to the general class of compounds called "surface-active agents" or surfactants.

FUNCTIONS

Promote emulsion stability, stabilize aerated systems and control agglomeration of fat globules.

Modify texture, shelf life and rheological properties by complexing with starch and protein components.

Improve the texture of fat-based foods by controlling the polymorphism of fats.

HOW DOES IT WORK??

Emulsifier's molecule structure have both polar and non-polar group. The presence of both regions on the emulsifier molecule allows them to orient themselves at the phase interface and lower the interfacial energy that leads to instability. It stabilize emulsion by means of monomolecular interfacial films and also by formation of steric and/or electrical barriers that prevent coalescence of the dispersed droplets.

APPLICATION

In bread, rolls and buns

  Bread is made by mixing and kneading flour, water, salt and yeast and baking the dough following fermentation. To maintain the softness for as long as possible and to make bread dough suitable for machine production, emulsifiers are used but not only for emulsification. It is also used as a dough modifier (or “dough conditioner”), tolerable to mechanical force, by modulating the proteins in wheat flour. These results in a dough that is tolerant to mixing, shows better retention of CO2 produced during leavening, and, when baked, yields a product with increased volume and finer texture. Emulsifiers used for shelf life extension, termed “crumb softeners” or “anti-staling agents”, assert their effects by forming water-insoluble inclusion complexes, yielding a considerably softer crumb structure, retard starch crystallization or retrogradation which is responsible for staling. Emulsifiers used for this application include distilled monoglycerides based on fully hydrogenated fats, diacetyl tartaric acid esters of mono- and diglycerides (DATEM), and propylene glycol mono- and diesters of fat-forming fatty acids. To summarise, the 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.  

Cakes

Cake batters have been described as complex w/o emulsions or air-in-fat foams, consisting of suspended flour particles, dissolved sugar, and proteins. Distilled saturated monoglycerides is added, that function as aerating agents, speeding up the whipping rate of the batter and providing a finer distribution of air cells. The more finely distributed air particles increase the viscosity of the batter, leading to a better volume and texture in the finished product. Moreover, the interaction between the emulsifier and amylose decreases starch gelatinization, leading to further improvements in the tenderness of the cake. Emulsifiers added to fat-containing batters function to ; (1) Stabilize the aerated structure. (2) Promote a finer distribution of the fat droplets.

Confectionery products and coatings

Emulsifiers are used primarily to inhibit bloom, stabilize gloss and improved palatability. Bloom, which occurs when fat crystals undergo transition from beta form to the most stable crystalline form, causing the cocoa butter to separate from the brown nonfat phase. The bloom defect can be retarded with the use of emulsifiers functioning as crystal modifiers.

Frozen dairy products - Ice Cream

In ice cream, emulsifiers function as aerating agent and foam stabilizer. It stabilize the foam by de-stabilizing the product's emulsion. Emulsifiers displace the protein from the fat globule surface to the aqueous phase which increase the liquid cream's viscosity and allows the fat globules to agglomerate. The increased viscosity promotes aeration, while the agglomerates stabilize the air cells once the air is incorporated.

Noodles and pasta

Emulsifiers make a rigid complex with starch to protect starch granules and improve the quality of starchy foods. In fresh noodles, an emulsifiers makes easy to handle dough and increases the water absorption rate by 1 to 2%. The surface of the noodle becomes smooth and uniform and less-sticky, resulting in improved for production. In instant noodles, emulsifiers improve absorption and decrease cooking time. For macaroni and spaghetti, emulsifiers provide a feeling of elasticity and a smooth uniform surface which inhibits sticking after boiling.

EMULSION

What is emulsion??

Emulsions are defined as mixtures of at least two immiscible liquids. The liquid that is dispersed as droplets is called the dispersed, discontinuous, or internal phase.  The surrounding liquid is called the continuous or external phase.

Types of emulsion

Stability of an emulsion

Stability of an emulsion depends on : Degree of division of the inner phase. Quality or stability of the interfacial film. Viscosity of the outer phase. Ratio and the specific weight of the volumes of the two phases.

Emulsion destabilization

An emulsion system can be destabilized through one of the following mechanism depending on the phase volume,droplet size, and the physical environment of the system : Creaming - Droplets density is lower than density of continuous phase. Flocculation - Process of two/more droplets "stick" together to form an aggregate. Coalescence - Process of two/more droplets merge to form single larger droplet. Sedimentation - Droplets density is higher than density of continuous phase. Phase inversion - Process in which O/W emulsion changes to W/O emulsion or vice versa.

TYPES OF EMULSIFIER

Polar head groups in emulsifier molecule may be present in a variety of functional groups. They may be incorporated to produce ionic, cationic, amphoteric, or nonionic surfactants. Nonionic – Uncharged molecules relatively insensitive to effects of pH and salt content. Most commonly used  food emulsifier type. Example: mono- and diglycerides, sorbitan esters,  sucrose esters, polysorbates, polyoxyethylene glycol oleates (all contain an –OH functional group). Anionic – posess a negative electrical charge; e.g., Stearoyl lactylates, diacetyl tartaric esters of monoglycerides (DATEM), succinylated monoglycerides; Functionality may be markedly influenced by pH and ionic strength. Cationic – Possess a positive electrical charge; e.g., amine compounds. Not used as food additive (toxic). Amphoteric – Possess both positive and negative charges; e.g., various lecithins; may act as anionic or cationic emulsifier, depending on pH of the system.

PROPERTIES OF EMULSIFIERS

Monoglycerides & Diglycerides

Most commonly used emulsifiers. Highly lipophilic with Hidrophilic-Lipophilic Balance (HLB) values range from 1 to 10. Produced by transesterification of glycerol and triacylcerides. Used in bakery products, frozen desserts, icings, toppings and peanut butter.

Sucrose Ester

Sucrose Ester are the monoglycerides, diglycerides and triglycerides ester of sucrose with fatty acids. Usually with HLB values from 7 to 13. Mono-esters have HLB values more than 16 for oil-in-water emulsion. Di-esters are good for water-in-oil emulsion. Tri-esters have HLB ~1

Sorbitan Ester

Sorbitan monostearate is the only sorbitan ester approved for food use. Produced by the reaction of sorbitol and stearic acid. Sorbitan ester have HLB of 4.7. It is used in conjunction with polysorbates in oil toppings, cake mixers and other products.

Polysorbates

Polyoxyethylene sorbitan esters. Formed from the reaction of sorbitan esters with ethylene oxide. There are a few types of polysorbates; Polysorbate 60, Polysorbate 65 and Polysorbate 80 which differ in the HLB values and its applications.

Stearoyl Lactylates

Stearoyl Lactylates is an example of ionic emulsifier. It is possibly the most hydrophilic emulsifier used in food. Lactic acid ester of monoglyceride with sodium or calcium. Form strong complex with gluten in starch. Valuable in baked products.

Lecithin and Derivatives

Lecithin and its derivatives is an example of amphipillic emulsifiers. It is a mixture of phospholipids including phodphatidyl choline, phosphatidyl ethanolamines, inositol phosphatides and etc. Rich in egg yolk. Derives commercially from soybeans. Can be chemically modified by providing a wide range of HLB. Widely used in baked goods, low-fats baked goods, chocolate, instant foods, confectionery products and cooking sprays.