New, Precise Methods for Encapsulation – R&D Applications – Brief Article
Encapsulated ingredients are used in many food applications. For example, acidulants are protected from oxidation and released at the right time to be effective as dough conditioners, flavorings and meat processing aids. Flavors are stabilized and protected until they release in the mouth or during the cooking process. Leavening agents are protected until the moment they can achieve maximum effect. Encapsulation also stabilizes vitamins, minerals and unsaturated molecules, reducing their potential to cause off-flavors.
Among the factors key to successful functioning of encapsulated ingredients are particle size and properly applying the coating to the ingredient particles. Particle and Coating Technologies Inc. (PCT), St. Louis, has several original methods for forming particles of the optimum size, size distribution, and coating particles with the appropriate material for protection, stability, controlled release, fast dispersion or increased bioavailability.
The particle size needed for different applications may vary from perhaps microns–for controlled release flavors from particles with no mouthfeel–to several millimeters for raisins or fruit pieces. The company has developed methods to produce particles from a wide range of materials, such as waxes, fats, aqueous solutions, microemulsions, suspensions, carbohydrates and polymers. Unusual atomizers can produce particles down to 1 micron for low viscosity fluids. Emulsification methods create particles down to 200nm and smaller. High speed, low temperature spray-drying methods have been developed to trap the fine primary particles in larger secondary particles, permitting easy handling and more control over release and dissolution rates.
A unique, proprietary atomizer permits the formation of narrow size distribution for mean particle sizes from 20 to 800 microns, with the middle 90% of the particles differing by less than a factor of two in diameter.
“When there is wide particle size distribution, the fines release much too fast,” says Robert Sparks, director, R&D. “Taste masking is greatly improved when there is no tail of small particles. In addition, there is no grittiness caused by large particles.”
A new, fast coating method has permitted coating and controlled release of flavor and fragrance particles, with a decreased loss of high notes. In another area, an unusual mechanism has permitted taste-masking of materials as well as stabilization of vitamins in food products — without the need to coat the particles.
PCT’s continuous, inexpensive, patented spinning disk coating technique works in seconds to minutes, coating particles one at a time, without aggregation. In this process, the core particles are first suspended in the liquid coating material. The suspension is then poured onto a rotating disc, where the core particles separate by moving radially, and the excess liquid spreads into a thin film between the core particles. Two different particles are formed at the edge of the disk: core particles coated with a layer of residual coating, and smaller droplets of excess coating material. All the particles fall through a drying or cooling tower, where they are solidified, after which the smaller coating particles are removed for recycling. The encapsulated product remains. The process can coat particles from about 20 microns to several millimeters in diameter.
Other applications of spinning disk particle coating include protecting ingredients from moisture absorption, stabilization and release of enzymes, and retarding oxidation. Coating nuts and other particles could help retard oxidation and maintain crispness and flavor. Raisins and other fruit pieces could be coated to maintain their moisture levels to prevent them from becoming hard.
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