Encapsulation involves the incorporation of food ingredients, enzymes, cells or different materials in small capsules. Applications for this method have increased within the food industry since the encapsulated materials may be protected against moisture, heat or different extreme conditions, so enhancing their stability and maintaining viability. Encapsulation in foods is also utilized to mask odours or tastes. Numerous techniques are used to make the capsules, including spray drying, spray chilling or spray cooling, extrusion coating, fluidized bed coating, liposome entrapment, coacervation, inclusion complexation, centrifugal extrusion and rotational suspension separation. Every of those techniques is discussed in this review. a large variety of foods is encapsulated–flavouring agents, acids bases, artificial sweeteners, colourants, and preservatives, leavening agents, antioxidants, agents with undesirable flavours, odours and nutrients, among others.
The use of encapsulation for sweeteners such as aspartame and flavours in chewing gum is well known. Fats, starches, dextrins, alginates, protein and lipid materials can be employed as encapsulating materials. Various methods exist to release the ingredients from the capsules. Release can be site-specific, stage-specific or signalled by changes in pH, temperature, irradiation or osmotic shock. In the food industry, the most common method is by solvent-activated release. The addition of water to dry beverages or cake mixes is an example. Liposomes have been applied in cheese-making, and its use in the preparation of food emulsions such as spreads, margarine and mayonnaise is a developing area. Most recent developments include the encapsulation of foods in the areas of controlled release, carrier materials, preparation methods and sweetener immobilization. New markets are being developed and current research is underway to reduce the high production costs and lack of food-grade materials.
The most important membrane and coating materials used for encapsulation are carrageenan, chitosan, sodium alginate, carboxy methyl cellulose (CMC), methylcellulose, cellulose acetate, polycarbonate, polysulfide, polyacrylate, collagen, Teflon, and phospholipids. Applying membranes that selectively allow analytes and products to permeate is a useful and precise technique; however, the biosensors based on this method usually have long response times. Membrane disruption caused by accumulation of side products is another disadvantage of this method.
Encapsulation can also be used to mask off-flavors. Iron supplements such as iron sulfate exhibit a typical unpleasant iron taste and color. These unwanted attributes could be masked using phospholipid-coated iron phosphate nanoparticles. The undesirable odor or flavor of soy products, sweeteners, and omega-3-fatty acids was reported to be significantly reduced using β-lactoglobulin nanoparticles or cyclodextrins for encapsulation. Nanoencapsulation has also been used bakeries in Western Australia, to mask the taste and odor of tuna fish oil, which is high in omega-3-fatty acids in bread. The delivery system releases the tuna fish oil only when reaching the stomach and hence the unpleasant taste of fish oil can be avoided. In addition, encapsulation extends shelf life of the omega-3-fatty acid-containing food products by protecting the polyunsaturated fatty acids from oxidation.
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