food
Encapsulation
The microcapsules act as barriers against odors and flavors and resist processing conditions and packaging
Encapsulation is a process by which bioactive food substances are introduced into a matrix to prevent the loss, to protect them from reacting with other compounds or to slow oxidation due to light or oxygen. In general, encapsulation is a means to pack, sort and store materials for later release under controlled conditions. This technology brings in the food sector, products with better sensory and nutritional characteristics.
food microcapsule developed at the Institute of Marine Sciences of Andalucía, Cádiz
- Picture: ICMAN-CSIC -
encapsulation processes were first developed between 1930 and 1940 by the National Cash Register (NCR ), Ohio, USA, for the commercial application of a dye from gelatin encapsulating agent. The food application is more recent, mainly due to cheaper technology, which has attracted interest from the food industry. This process allows, depending on the applied technology to encapsulate nutrients are not attacked, degraded or oxidized, as well as enzymes or whole cells, allowing substrates and products into and out of the capsule.
The latter idea was applied in the development of an artificial liver, liver enzymes placed in semipermeable membranes to improve their function. Nylon membranes have been used to encapsulate and entrap enzymes like pepsin, pectin esterase, Invertase for sucrose inversion and renin for coagulation of milk. Even as lactic acid bacteria Lactobacillus lactis can also be encapsulated, which could facilitate the production of fermented products continuously.
microcapsules for production have been proposed various methods are divided into physical processes (spray drying, extrusion and spray coating) physicochemical processes (simple or complex coacervation and entrapment in liposomes) and chemical processes. The choice of method depends on the average particle size required and the physicochemical properties of encapsulating agent and the substance to be encapsulated, applications for microencapsulated material, the release mechanism required and cost.
Spray drying and spray chilling
The encapsulation of flavors prevent undesirable reactions with other food components, even for a long storage process have been developed various methods for encapsulating flavors and aromas. Spray drying is the most used in the food industry because it is a cheap and effective in the protection of materials. Modified starches, maltodextrins and gums are used as wall materials. The encapsulated material is homogenized with the carrier. Subsequently, the mixture is spray dried and sprayed through a nozzle or disk. After this process, the capsules formed are collected ready to be employed.
are currently studying new materials wall, including colloids and natural gums, for obtaining mixtures which increase the retention of volatile compounds and the commercial life of the microcapsules. Thus, we have obtained the retention of essential oils of orange and decreased oxidation by using gum arabic, which undoubtedly allows the inclusion of active substances without being affected by the process of digestion begins in the mouth and stomach.
Another method is to spray chilling or freezing, which consists in mixing the material to be encapsulated with the product carrier and atomized by means of cold air. The microcapsules produced by spraying the emulsion or suspension containing the wall material and active ingredient of solid or liquid. The coverages are vegetable oils used in the case of spray chilling or hydrogenated vegetable oil spray to freeze, and can be encapsulated heat-sensitive liquids and materials that are insoluble in conventional solvents.
reduction produces a solidification temperature of the lipid that acts as a wall and the entrapment of the active substance in the center of the capsule. The spraying of cooling is usually used to encapsulate ferrous sulfate, vitamins, minerals or acidulants. The most common applications of spray freeze include dried soups and foods high in fat. The microcapsules produced by cooling or freezing are insoluble in water due to its coverage of lipids, which are encapsulated soluble materials such as enzymes, vitamins and water soluble acidulants.
Other methods
Microencapsulation by extrusion, developed another method involves the passage of an emulsion of active material and the wall material through a die at high pressure. The extrusion process is the second most used, after spray drying for the encapsulation of flavors. A typical process involves mixing flavored with corn syrup and modified starch hot extruding the mixture into small sphere ( pellets) in a bathroom with a cold as isopropoanol solvent. The cold solvent syrup solidifies into an amorphous solid, bathing the flavors. The flavors have a longer life as well. Vitamin C and dyes may have a shelf life exceeding two years, and are protected from oxidation. In addition, the solid form of flavors is more convenient to use. The application of this method in food processing includes drinks, cakes, jellies and desserts.
coverage fluidized bed consists of particles suspended sound in air at high speeds inside a chamber with controlled temperature and humidity, which sprays the wall material. The amount of coated particles depends on the length of the camera and the residence time within it. The technique is applicable to coatings that melt easily (such as hydrogenated vegetable oil, stearin, fatty acids, emulsifiers and waxes) or soluble coverage (such as starches, gums and maltodextrin). For hedges that melt cold air is used to harden the carrier, while for the coating soluble hot air is used to evaporate the solvent. The ingredients are easy to blend released by increasing temperature or by physical disruption, coverage while soluble release their contents by adding water. Some fortified foods and nutritional ingredients encapsulated mixtures fluidized bed, for example: citric, lactic and sorbic acid or sodium bicarbonate used in bakery products.
A type of housing properties with more versatile and less fragile than those made of fat is of the liposomes used for the release of vaccines, enzymes and vitamins in the body after passing through the initial stages of the digestive tract. The method of encapsulation in liposomes consists of one or more layers of lipids and acceptable non-toxic food whose permeability, stability, surface activity and affinity may vary with the size and composition of the lipid. Liposomes are vesicles that form when phospholipids are dispersed films in an aqueous medium. They act the same way as natural membranes, being selectively permeable to ions.
APPLICATIONS IN FOOD SAFETY
A major advantage of encapsulation is the ability to retain certain food substances or microorganisms and protect them from the action of the stomach, allowing the passage into the intestine of microorganisms and nutrients are not altered with proven nutritional and digestive protection. At the same time, it is possible to encapsulate drugs, which opens the door to the use of substances that could not stand the passage through the stomach and the first sections of the alimentary tract and, according to this principle, may be administered via oral.
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