Process For Popping Amaranth

Apparatus and process for expanding raw amaranth

United States Patent 5069923

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Abstract:An apparatus and process are disclosed for expanding raw, wholeseed amaranth and extruded half products of cereal grains. Amaranth (for example), after tempering to a predetermined moisture content, is fed at a steady rate to a cylindrical popping drum having perforations sufficiently small to contain both raw and expanded amaranth. Popping is accomplished with air heated to a temperature of from 450 to 500 degrees F., forced into the popping drum from below to provide a fluid bed for supporting the amaranth. An auger in the popping container is rotated to move the amaranth through the container as it is being popped, further agitating the amaranth. Following expansion, the expanded amaranth is separated from unexpanded amaranth and other unwanted matter, either in a perforated, revolving separating drum, or on an inclined, vibrating screen.

BACKGROUND OF THE INVENTION

The present invention relates to processing grains, and more particularly to a means for expanding raw, wholeseed amaranth and extruded half products of cereal grains such as corn, wheat and oats.

Amaranth is a pseudo grain in the nature of buckwheat, used for many years in certain regions of Asia and South America. Just recently introduced into the United States, amaranth is rapidly gaining acceptance, particularly among consumers interested in health and the nutritional value of food products. In particular, amaranth is high in protein content, whereby amaranth flour can be combined with wheat flour to provide enriched flours and pancake mixes. While not a true cereal grain, amaranth is used in cereal products as well.

Another amaranth product is based upon the fact that amaranth, in the raw, wholeseed form, includes entrapped moisture. Upon a sufficiently rapid heating, the moisture expands the seed. This puffs or pops the amaranth, much in the same manner as popping corn is expanded or popped. Popped or puffed amaranth is generally spherical and about one-eighth of an inch in diameter, approximately six times (or more) the size of the raw, unpopped grain. Accordingly, puffed amaranth tends to be used as a filler to add nutrition to certain baked goods, to garnish salads, and the like. The conventional approach to popping amaranth is on a small batch basis, e.g. stove-top popping with oil, in a frying pan or the like. This must be done with care, as there is a narrow range of tolerance between insufficient heating of the amaranth to achieve popping, and excessive heating leading to charring or burning.

In recent years, concern about the greasy texture and calorie content of popcorn prepared using fats or oils, has increased the popularity of hot air corn poppers. U.S. Pat. No. 4,767,635 (Merritt et al) discloses a method for flavoring popping corn, including mixing unpopped corn with an aqueous coating mixture consisting essentially of an edible adhesive, and a flavoring such as an edible salt or other flavorant. The edible adhesive can include proteinaceous adhesives such as gelatin, alginates such as propylene glycol alginate, pectin, gums and gum arabic. The mixture is then dried to a moisture content of about 11-14 percent by weight. Thus treated, the mixture is said to retain substantially all of the added flavor upon being popped in a hot air popper.

Other foods suitable for puffing or expanding include extruded flours of amaranth and cereal grains such as corn, wheat and oats. Frequently, such products are puffed or popped by deep-fat frying, again raising concerns about the calorie content.

Alternatives to deep-fat frying are known in connection with various grain based food products. For example, U.S. Pat. No. 3,689,279 (Bedenk) discloses a high protein ready-to-eat breakfast cereal, made from a dough which is formed by combining gelatinized cereal grain (preferably corn, but also possibly wheat, oats or rice) with partially hydrolyzed soy isolate. The resultant dough is processed through an extruder into strands, which are sliced to form pellets. Following tempering to a moisture content of 12-14 percent, the pieces of dough are puffed, for example, by a process of heating under pressure followed by rapid release of the pressure.

In U.S. Pat. No. 1,946,803 (McKay), a mixture of rice and a solution of sugar, salt and water is cooked, cooled and dried, ground to small particles and tempered for uniformity in moisture content, rolled into ribbons, dried, broken into fragments and finally toasted and puffed in a rotary toaster at a temperature of 450-600 degrees F.

While the above and many other processes have proven satisfactory in connection with certain foods, these approaches do not adequately address the need for low cost, reliable approach for expanding amaranth and grain half products.

Therefore, it is an object of the present invention to provide an efficient means for a large scale production of popped amaranth and grain half products; another object is to provide a means of expanding amaranth and half products of certain grains in a manner which results in a more nutritious food product; yet another object is to provide an improved process for popping raw, wholeseed amaranth, resulting in a more consistent product available at lower cost.

SUMMARY OF THE INVENTION

To achieve these and other objects, there is provided an apparatus for expanding amaranth and half products of cereal grains. The apparatus includes a first container for receiving and tempering raw, wholeseed amaranth. A second container is provided for the amaranth, having a wall defining a chamber for the amaranth, with multiple perforations through the wall. The perforations are substantially uniform in size and sufficiently small to substantially prevent passage of raw amaranth therethrough. A first transfer means is provided for moving the amaranth from the first container to the second container at a uniform rate. An agitation means is provided in the second container for agitating amaranth contained in the chamber. Means are provided for heating air to a temperature sufficient for popping the raw amaranth, and for supplying the heated air to the chamber through the perforations, thus to expand at least a substantial portion of the raw amaranth contained in the chamber. Finally, a separating means receives an output of the second container, and separates the expanded amaranth from raw, unpopped amaranth and other matter.

Preferably the second container is a cylindrical drum having a cylindrical wall formed largely of a 28 mesh screen. This screen forms a highly porous wall, yet with openings sufficiently small to retain both popped and unpopped amaranth within the chamber. The preferred agitation means is an auger, which, when rotated, moves the amaranth at a steady rate from the input end to the output end of the cylindrical drum.

The heated air which expands the amaranth is supplied to the chamber from below, and should be supplied with sufficient force so that the amaranth tends to be carried on a bed of air, rather than coming to rest on the bottom portion of the cylinder wall. This enhances the mixing action, as well as preventing lodging of material where it might burn or possibly jam the auger.

The preferred transfer means is a motor driven paddle wheel. The feed rate of tempered raw amaranth into the second container is thus controlled by adjusting the speed of the paddle wheel drive motor, enabling precise control of the feed rate.

One suitable separating means is a cylindrical drum with walls formed of a 12 mesh screen. The 12 mesh screen provides openings sufficiently large for passage of raw, unpopped amaranth while retaining the expanded product. The separator drum is rotated to facilitate separation and removal of the raw amaranth, which is collected in a bin below the drum.

Alternatively, a particularly effective separation means employs an inclined, flat 28 mesh screen which is vibrated as it supports the output from the chamber. As the screen vibrates, puffed amaranth tends to ride downwardly toward one end of the screen. Conversely, unpuffed amaranth and other material of similar density tends to ride upwardly, to the opposite end of the screen. A jet of air can be directed upwardly through the screen, to cool the amaranth, and to carry dust and other light particulate matter upwardly away from the puffed amaranth. The result is a particularly clean, uniform expanded amaranth product.

Another aspect of the present invention is a process for expanding raw, wholeseed amaranth grain. The process includes the following steps: tempering raw, wholeseed amaranth to a substantially uniform moisture content in the range of from 15-17 percent; agitating the tempered amaranth in a porous container, and simultaneously directing a stream of heated air onto the amaranth from outside of and beneath the container, thus to form a fluid bed supporting the amaranth as the heated air pops the amaranth; and following popping, separating the popped amaranth from the unpopped amaranth and other matter.

The preferred moisture content after tempering is 16 percent by weight, with the tempered raw amaranth being fed to the container at a uniform rate, then moved through the container by a rotating auger as it is popped, and agitated by the combined action of the auger and the forced, heated air.

For satisfactory popping of the amaranth, the forced air providing the bed is heated to a temperature in the range of from 400-600 degrees F., and more preferably in the range of from 450-500 degrees F. By controlling the temperature, the feed rate and the moisture content of the raw amaranth after tempering, a consistently high quality puffed amaranth product is achieved on a large scale and at relatively low cost, facilitating the use of puffed amaranth as a food additive. As popping is accomplished without oils or fats, the calorie content of the amaranth or half product is minimized, further enhancing its value as a nutrition-enhancing food additive.