Product Examples

Agglomerated food products are inseparable from some specific processes that were used to obtain these products. Steam fusion/steam jet agglomeration is used for agglomerating water-soluble instant beverage powders with high sugar content like cocoa drinks or products containing coffee extract (Fig. 5). After grinding, the particles with an average particle size of 25 to 75 /¿m are fed into an agglomeration chamber in the shape of dry clusters (average size up to the mm range). A uniformly distributed curtain of powder moves downward where it interacts with jets of steam. Steam wets the particles and fuses them into agglomerates. The wetted agglomerates pass from the top section of the agglomerating tower into a drying zone in the bottom portion of the tower, which is supplied with hot air. The agglomerates are dried and then cooled and screened. Critical parts of this agglomeration process are the feed port section, where initial cluster formation oc-

Agglomerated product Powder

Figure 5. Principle flow diagram of a steam fusion/steam jet agglomeration process.

Agglomerated product Powder

Figure 5. Principle flow diagram of a steam fusion/steam jet agglomeration process.

curs, and the steam jet zone, where further agglomeration by collision of sticky clusters takes place (8).

A method for making agglomerated bits containing aspartame includes preblending aspartame and a bulking agent (maltodextrin) to form a premix (13). The latter is then mixed with other dry ingredients (flavors, starch binders, dispersing agents, and vitamins) to form a dry mix. Liquid ingredients (vegetable oil and water) are blended into a dry mix with a ribbon blender or a paddle mixer to form moistened clumps. These granules must be dried in a forced-air convection oven and then screened to obtain a desirable particle size distribution. While starches (tapioca, corn, potato, modified wheat) and gums are used as the binders in forming agglomerates, baking soda and maltodextrin assist in the dispersion of the agglomerated product. These bits are suitable for use in home-cooked grain cereals and other foods.

Agglomerated potato granules can be prepared from a mixture of potato granules, egg white solids, and water (14). After the wet premix is formed, a gentle sieving, drying, and crushing are used to obtain agglomerates with the desired size and density.

Agglomerated bread crumbs may be produced from a starch containing raw material (flour, meal) and water in a continuous pellet mixer (15); subsequent baking in a humidified atmosphere (to control the desired gelatinization) and sizing (cutting) of the agglomerates are utilized. A controlled rétrogradation (recrystallization of starch) occurs due to the controlled cooling process.

Agglomerated beverage blends having aspartame as a sweetener may be manufactured to prevent clumping of aspartame and to improve its water dispersibility (16). Agglomeration has been conducted in a jacketed blender so that a heating or cooling fluid may be passed through the jacket while the blender is rotated to provide adequate mixing. The blending time and temperature (but not, however, humidity) were controlled to obtain a desired agglomerate size distribution.

Aqueous, sugary syrups (honey, high fructose corn syrup, invert sugar, corn syrup, etc) were dehydrated using thin film drying in the presence of binders (soy protein and ungelatinized starch that was partially gelatinized in situ) (17). A spray of water was added during tumbling. The resultant agglomerates were dried and then slightly coated with a high melting point fat, apparently to prevent caking.

Agglomerates of garlic, onion, and their mixtures were produced in an upright chamber (18). Wetting of particles was provided by atomized water in the upper part of this chamber, followed by drying of the agglomerated product with air in the lower part of the chamber.

An agglomerated milk product was prepared by spraying a concentrate of milk into a stream of drying gas directed against the surface of a fluidized layer of already spray-dried particles (19). Adjustment of temperatures, flow rates of drying air, and residence times allowed better efficiency for skim milk, whole milk, and whey particles.

Agglomerates of meat analogues were prepared by extrusion cooking of soy concentrate, comminution of the ex-

trudate, mixing it with a water slurry of binder, frying the mixture in edible fat or oil to produce an agglomerated mat, and sizing (20). Particles with the desired size distribution were used for meat-type sauces.

A porous and pelletized food product may be formed by premixing two or more ingredients, one of which is capable of forming sticky bonds after being moistened by an aqueous medium (21). This interaction occurs when the mixture of particles is tumbled and rolled on a pelletizing disc; the adhered particles form pellets or wet aggregates. Examples of a dry mix may include sugars, starches, dried milk products, proteinaceous materials, dehydrated juices, and powdered coffee concentrates. Some of these products (sugars, starches) may become self-adherent in contact with water and are used to form agglomerates. To provide pellets with controlled porosity, the particulate mixture also includes a chemical leavening system (sodium bicarbonate and leavening acid). Once moist agglomerates are in contact with hot air, two processes take place: drying and formation of gaseous carbon dioxide (due to a reaction between the bicarbonate and leavening acid). The resulting pellets have a porous, cellular structure with a crisp, crunchy, and friable texture.

The vast majority of gelatin dessert mixes require the use of hot water to dissolve the gelatin and an extended time (3-4 h) to prepare the meal. However, if gelatin-containing mix with a limited moisture content of 1 to 3% is agitated and slowly heated to 190 to 195°F, it forms agglomerates (22). Subsequent cooling helps to form so-called cold-water-soluble gelatin, which dissolves and disperses in water at 40 to 50°F. Agglomeration of gelatin mixes (ie, sucrose, gelatin, citric acid) was conducted in a jacketed rotating blender.

Other agglomerated (instantized) products include mal-todextrin and dextrose, which may be used as carriers for flavors, colors, and nonnutritive sweeteners in instant beverages and desserts (23,24), soy protein isolates for highprotein beverage blends and for better dispersibility in meat emulsions, prejelled starches and gums as soup thickeners, whey protein concentrates and calcium casemates for dairy blends, all developed by IFT, Inc. (25), and coated animal feed with improved nutritional value (26). Powders such as egg proteins, cocoa, or various fibers will have improved dispersibility after agglomeration in the presence of maltodextrin or surfactants (27).

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