Encapsulation in the food industry: a review

Encapsulation involves the incorporation of food ingredients, enzymes, cell s or other materials in small capsules. Applications for this technique hav e increased in the food industry since the encapsulated materials can be pr otected from moisture, heat or other extreme conditions, thus enhancing the ir stability and maintaining viability. Encapsulation in foods is also util ized to mask odours or tastes. Various techniques are employed to form the capsules, including spray drying, spray chilling or spray cooling, extrusio n coating, fluidized bed coating, liposome entrapment, coacervation, inclus ion complexation, centrifugal extrusion and rotational suspension separatio n. Each of these techniques is discussed in this review. A wide variety of foods is encapsulated - flavouring agents, acids, bases, artificial sweeten ers, colourants, preservatives, leavening agents, antioxidants, agents with undesirable flavours, odours and nutrients, among others. The use of encap sulation for sweeteners such as aspartame and flavours in chewing gum is we ll known. Fats, starches, dextrins, alginates, protein and lipid materials can be employed as encapsulating materials. Various methods exist to releas e the ingredients from the capsules. Release can be site-specific, stage-sp ecific or signalled by changes in pH, temperature, irradiation or osmotic s hock. 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 preparat ion of food emulsions such as spreads, margarine and mayonnaise is a develo ping area. Most recent developments include the encapsulation of foods in t he areas of controlled release, carrier materials, preparation methods and sweetener immobilization. New markets are being developed and current resea rch is underway to reduce the high production costs and lack of food-grade materials.