What are preservatives and emulsifiers?!
Answers: I have read somewhere that they are divided into certain classes. why is that so?
A preservative is a natural or synthetic chemical that is added to products such as foods, pharmaceuticals, paints, biological samples,wood, etc. to prevent spoilage, whether from microbial growth or undesirable chemical changes.
Preservatives may be added to wood to prevent the growth of fungi as well as to repel insects and termites. Typically copper, borate, and petroleum based chemical compounds are used. For more information on wood preservatives see timber treatment, lumber and creosote.
Preservative food additives can be used alone or in conjunction with other methods of food preservation. A distinction is sometimes made between anti-microbial preservatives which function by inhibiting the growth of bacteria and fungi, and antioxidants such as oxygen absorbers, which inhibit the oxidation of food constituents. Common anti-microbial preservatives include calcium propionate, sodium nitrate, sodium nitrite, sulphites (sulfur dioxide, sodium bisulfite, potassium hydrogen sulfite, etc.) and disodium EDTA. Antioxidants include BHA and BHT. Other preservatives include formaldehyde (usually in solution), glutaraldehyde, diatomaceous earth (kills insects), ethanol and methylchloroisothiazolinone. The benefits and safety of many artificial food additives (including preservatives) are the subject of debate among academics and regulators specializing in food science and toxicology.
Foods such as salt, sugar or vinegar are also used as traditional natural preservatives. There is also two different ways to preserve food, and those are freezing food, or smoking food. Another group of preservatives targets enzymes in fruits and vegetables that continue to metabolize after they are cut. For instance, citric and ascorbic acids inhibit the action of the enzyme phenolase which turns surfaces of cut apples and potatoes brown.
An emulsion is a mixture of two immiscible (unblendable) substances. One substance (the dispersed phase) is dispersed in the other (the continuous phase). Examples of emulsions include butter and margarine, espresso, mayonnaise, the photo-sensitive side of photographic film, and cutting fluid for metal working. In butter and margarine, a continuous liquid phase surrounds droplets of water (water-in-oil emulsion). Emulsification is the process by which emulsions are prepared.
Emulsions tend to have a cloudy appearance, because the many phase interfaces (the boundary between the phases is called the interface) scatter light that passes through the emulsion. Emulsions are unstable and thus do not form spontaneously. Energy input through shaking, stirring, homogenizers, or spray processes are needed to form an emulsion. Over time, emulsions tend to revert to the stable state of oil separated from water. Surface active substances (surfactants) can increase the kinetic stability of emulsions greatly so that, once formed, the emulsion does not change significantly over years of storage. Homemade oil and vinegar salad dressing is an example of an unstable emulsion that will quickly separate unless shaken continuously. This phenomenon is called coalescence, and happens when small droplets recombine to form bigger ones. Fluid emulsions can also suffer from creaming, the migration of one of the substances to the top of the emulsion under the influence of buoyancy or centripetal force when a centrifuge is used.
Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion tends to imply that both the dispersed and the continuous phase are liquid.
There are three types of emulsion instability: flocculation, where the particles form clumps; creaming, where the particles concentrate towards the surface (or bottom, depending on the relative density of the two phases) of the mixture while staying separated; and breaking and coalescence where the particles coalesce and form a layer of liquid.
Emulsion is also a term used in the oil field as untreated well production that consists primarily of crude oil and water
well these are ingredients mentioned on packaged foods in India. They are added to preserve and enhance the taste of the product being consumed. For instance, we have tamrind rice, which contains natural ingredients such tamrind, salt, edible oil, and sodium bi-carbonate, citric acid which acts as preservative. Sometimes ajana motto is also added
a surface-active agent that promotes the formation of an emulsion is an emulsifier and a preservative is an agent which is used to perserve the food. and different types of food need differnt types of preservatives and emulsifiers. some foods stuffs can last longer and some cannot depending on this we have to used the preservaties and emulsifiers accordingly.
Preservatives :
-A preservative is a natural or synthetic chemical that is added to products such as foods, pharmaceuticals, paints, biological samples,wood, etc. to prevent spoilage, whether from microbial growth or undesirable chemical changes.
-Preservatives may be added to wood to prevent the growth of fungi as well as to repel insects and termites. Typically copper, borate, and petroleum based chemical compounds are used. .
-Preservative food additives can be used alone or in conjunction with other methods of food preservation.
-A distinction is sometimes made between anti-microbial preservatives which function by inhibiting the growth of bacteria and fungi, and antioxidants such as oxygen absorbers, which inhibit the oxidation of food constituents.
-Common anti-microbial preservatives include calcium propionate, sodium nitrate, sodium nitrite, sulphites (sulfur dioxide, sodium bisulfite, potassium hydrogen sulfite, etc.) and disodium EDTA. Antioxidants include BHA and BHT. Other preservatives include formaldehyde (usually in solution), glutaraldehyde, diatomaceous earth (kills insects), ethanol and methylchloroisothiazolinone.
-The benefits and safety of many artificial food additives (including preservatives) are the subject of debate among academics and regulators specializing in food science and toxicology.
-Foods such as salt, sugar or vinegar are also used as traditional natural preservatives.
-There is also two different ways to preserve food, and those are freezing food, or smoking food.
-Another group of preservatives targets enzymes in fruits and vegetables that continue to metabolize after they are cut. For instance, citric and ascorbic acids inhibit the action of the enzyme phenolase which turns surfaces of cut apples and potatoes brown.
EMULSIFIER
-Food is a complicated mixture of carbohydrate protein, oil and fat, water, and air, as well as a variety of other minute components such as minerals, vitamins, and flavors. Food processing subjects this mixture to a wide range of thermal treatments, such as baking, boiling, steaming, freezing; and mechanical treatments, such as kneading, mixing, extruding etc, all of which futher complicate the structure of the food. The desired result of these treatments is good tasting food. For this reason, products with inproved flaver, texture and quality are always in demand.
The challenge is to bring together the deiverse and often conflicting natural components of food into a consistent and pleasing blend. Each component of food (carbohydrate, protein, oil and fat, water, air, etc.) has its own unique properties which sometimes come into conflict with other components, for example, oil and water. Thus a third substance is neccessary to increase the compatibility of the contact surfaces of the two components, that is, to serve as an interface between two mutually exclusive materials, The substance which is used to improve the quality of food and its processing is called a food emulsifier
-An emulsifier (also known as an emulgent) is a substance which stabilizes an emulsion, frequently a surfactant. Examples of food emulsifiers are egg yolk (where the main emulsifying chemical is the phospholipid lecithin), and mustard, where a variety of chemicals in the mucilage surrounding the seed hull act as emulsifiers; proteins and low-molecular weight emulsifiers are common as well.
-In some cases, particles can stabilize emulsions as well through a mechanism called Pickering stabilization. Both mayonnaise and hollandaise sauce are oil-in-water emulsions that are stabilized with egg yolk lecithin. -Detergents are another class of surfactant, and will chemically interact with both oil and water, thus stabilising the interface between oil or water droplets in suspension.
-This principle is exploited in soap to remove grease for the purpose of cleaning.
- A wide variety of emulsifiers are used in pharmacy to prepare emulsions such as creams and lotions.
-20 ml ampule of 1% propofol emulsion suitable for intravenous injection. The manufacturers emulsify the lipid soluble propofol in a mixture of water, soy oil and egg lecithin.Whether an emulsion turns into a water-in-oil emulsion or an oil-in-water emulsion depends on the volume fraction of both phases and on the type of emulsifier.
-Generally, the Bancroft rule applies: emulsifiers and emulsifying particles tend to promote dispersion of the phase in which they do not dissolve very well; for example, proteins dissolve better in water than in oil and so tend to form oil-in-water emulsions (that is they promote the dispersion of oil droplets throughout a continuous phase of water).
They are the proof of why you learn to cook .They don't belong in your mouth..
obviously these both things are different. preservetives are use to protect food for long time such as salt, different sauces, sugar etc. and,
emultion is a process of mixing one liquid in another in which it is insoluble.
Yeah.......they are different........
Preservatives are added to preserve the food from bacteria, fungus, etc.,
Emulsions are any mixture of liquids that do not normally mix together, such as oil and water.
Have a great day Dia :-)