Process for Producing Round Spherical Free Flowing Blown Bead Food Products of Controlled Bulk Density

The present invention is concerned with the preparation of food products in the form of blown beads, and particularly to the preparation of food products in the form of round spherical free flowing expanded beads.

A number of food products are prepared by spray drying expandable liquid compositions to obtain edible blown beads. Such products include edible bulking materials, food flavorings, food sweeteners, food colorings, spices, dehydrated drinks such as tea, coffee, and flavored drinks.

The spray drying of products suitable for human consumption involve certain precautions and limitations in view of the materials employed. For instance, temperatures of the drying and the length of time that the food material can be exposed to elevated temperatures are limited because of their possible detrimental effect on the quality of the product.

Many of the blown beads do not have particle shells sufficiently strong to maintain their integrity and resist vapor holes from forming during expansion or resist crushing during shipment. This results in a nonuniform looking product which detracts from its commercial appeal.

A further recurring problem in preparing blown beads of food products is control of the bulk density of the blown bead. This is especially important in consumer products where the product may be used by the spoonful. This is also important in packaging in a container of predetermined volume where slack fill and excessive overfill are to be avoided.

Accordingly, it is an object of the present invention to provide a process for preparing edible products in the form of round spherical free flowing blown beads whereby the bulk density of the beads can be regulated and rendered substantially uniform. A further object of the present invention is to provide a process whereby the strength of the particle shell or walls are increased thereby greatly reducing, if not substantially eliminating altogether, the formation of vapor holes.

A further object of the present invention is to provide as much as possible the agglomeration of undivided blown beads during the processing.

The present invention is concerned with preparing edible food products in the form of blown beads and includes providing a sprayable composition which includes an edible film forming food product, a liquid which is in an amount sufficient to render the composition flowable, and a blowing agent. The composition is sprayed or atomized to thereby form beads which are subjected to a heated zone to cause expansion and drying thereof. Next, the beads are subjected to a cooling zone with a temperature sufficiently low so as to quench cool the beads.

By the particular combination of subjecting the beads to a zone at elevated temperature, followed by quench cooling, it is possible to regulate the particle size of the beads and bulk density depending on the relative flow rate of the beads and relative temperatures and times in which the beads are subjected to the elevated temperature and to the cooling zone. In addition, it has been noted that beads prepared by the above process have increased wall strength.

FIG. 1 is a schematic elevated diagram of one type of spraying apparatus suitable for carrying out the process of the present invention.

FIG. 2 is a schematic elevated diagram of a further type of apparatus suitable for carrying out the process of the present invention.

The composition to be treated according to the present invention must include an edible food material which is capable of forming a film during the atomization and must include such material in sufficient amounts so as to provide a bead of adequate strength. Included among the suitable food materials are carbohydrates such as the dextrins, starch, pectin, algin, methyl cellulose, carboxy methyl cellulose, carboxy methyl amylose, carboxy methyl amylopectin, dextrose, fructose, maltose, lactose, and dextrans, natural gums such as tragacanth, acacia, arabic, locust bean, caraya, and carragean. In addition, aqueous extracts of coffee, tea, chocolate, yerbamate, roasted cereal products such as simulated coffee products can be employed. Further included in the types of materials suitable for the present invention are cereal products such as extracts of grains or finely divided cereal material made from wheat, barley, malted barley, rice, corn, hydrolized cereal solids and the like.

Mixtures of the above edible materials with each other or with other edible materials can be employed, when desired. For instance, the present invention is applicable to providing a low bulk density carrier in combination with and preferably encapsulating a flavor such as coffee, chocolate, and tea; colors; or sweetening agents. Suitable sweeteners include natural sweeteners such as fructose, sucrose, invert sugar, honey, polysaccarides, extracts from orange and grapefruit peels, and artificial sweeteners including cyclamates, saccharin, and aspertane. Preferred carriers include maltose, lactose, finely divided cereal materials, and dextrins.

As noted above, the process of the present invention is of wide applicability and can be applied to edible food products of many types. It is noted that when the materials are already of a liquid character, they may be converted into beads directly or after suitable adjustment of texture and processed as hereindescribed to yield the blown beads. Where the food materials are of a solid nature, they may be converted to liquid form by application of conventional techniques such as admixing with water or other suitable liquid, extraction with water, comminuting, pressing, cooking in water, steaming or other known techniques as may be applicable to the particular material in question.

It is recognized that mixtures of food products are contemplated for application in the process of the present invention.

The composition to be sprayed must also include a liquid material in an amount sufficient to render the composition flowable. As discussed hereinabove, the liquid may already be present along with the film-forming material or may have to be incorporated therein. The preferred liquid is water. However, other edible liquids as long as they are compatible with the particular film-forming material employed and are readily vaporizable at the temperatures employed can be used. Such other liquids include propylene glycol, ethanol, glycerol, and sorbitols.

The other essential ingredient in the composition is a blowing agent. The blowing agent can be a gas per se or a compound which upon exposure to the elevated temperatures in the heated zone will form a gas in situ. Exemplary of suitable gases are nontoxic gases such as air, nitrogen, carbon dioxide, nitrous oxide, helium, propane, n-butane, isobutane, dichlorodifluoromethane, trichloromonofluoromethane, and monochlorotrifluoromethane. Those compounds which will form a gas in situ must form nontoxic gases such as being capable of forming gases such as nitrogen, ammonia, carbon dioxide, and the like. Some well known blowing agents for this purpose include ammonium salts such as ammonium carbonate, and ammonium bicarbonate. The preferred blowing agent is ammonium bicarbonate.

When a gas is employed, it may be incorporated into the liquid composition by any conventional methods used such as for instance in aerating ice cream, salad dressings, and the like. A simple method when air is to be incorporated is to whip the liquid with a rotating wire whip which beats air into the mixture. Another method involves use of a closed vessel such as a Pfaudler reactor with anchor adjator and baffle.

In addition to the above required constituents, the sprayable composition can contain other constituents such as those which are commonly employed in amounts effective for their intended purpose and including flavors, sweeteners, coloring agents, foam stabilizers (e.g., surface-active agents), and the like. Examples of suitable surface-active agents are fatty acid partial esters of sorbitol anhydrides, and polyoxyethylene derivatives thereof commercially available under the trade designations Span and Tween, respectively. These surface-active agents further provide a slight sweetening effect.

The relative amounts of the required ingredients. can vary over a wide range as long as the composition is flowable, sprayable, and contains sufficient blowing agent to provide the required bulk density. It will be evident to those skilled in the art from reviewing the present application that the sprayable and flowable composition should be a thick, more or less pasty consistency so that it will be amenable to forming a stable foam.

Typical compositions suitable for the present invention contain from about 5 to about 90% and preferably from about 25 to about 75% by weight of the film-forming edible material, from about 5 to about 60% by weight of the liquid, and from about 0.5 to about 10% by weight of a blowing agent which forms a gas in situ.

Furthermore, when a gas rather than a material which forms a gas in situ is employed, the amount of gas incorporated into the liquid may generally be enough to increase the volume of the liquid at least about 11/2 times and preferably from about 2 to about 10 times the original volume of the liquid.

After the compositions are obtained, they are sprayed or atomized employing any of the conventional types of atomizing devices suitable for spray drying. A description of some types of atomizing devices is contained on pages 838-848 of Chemical Engineers Handbook, edited by John H. Perry, 3rd Edition, McGraw-Hill (1950). Such principal atomization devices include low pressure, high volume atomizers (e.g., Moyno type pumps), high-pressure nozzles, pressurized by high-pressure pumps to 2000-6000 psi 2-fluid nozzles, and high-speed rotating discs. A typical spray nozzle means suitable for carrying out the process of the present invention includes a spray pressure system such as produced by Spray System, Inc. employing a core and spinner type of arrangement such as a Model 58 or 68 core along with a Model 21 or 17 insert.

The size of the nozzles can vary over a wide range and is primarily dependent upon the desired volume of materials to be introduced into the drying zone and the initial particle size of the bead prior to expansion. The nozzle size should not be so large that the particle size is so large that the particles do not remain in the heated zone long enough to be dried. The insert or spinner employed determines the angle at which the sprayed particles enter the heating zone.

The composition to be sprayed is usually at a temperature between about 55.degree. F. and about 200.degree. F. as it enters the atomizing device, and preferably from about 75.degree. F. to about 190.degree. F. The sprayed or atomized composition is directed to a high temperature atmosphere in order to cause expansion of the beads and to dry the beads by evaporation of the liquid from the surface thereof. Generally, the inlet temperature of the heated drying zone is between about 320.degree. and about 800.degree. F. and preferably between about 350.degree. and about 525.degree. F. The amount of time in which the sprayed beads remain in the heated zone will be governed by the particular bulk density desired to the final product. The longer the material is in the heated zone, the lower the bulk density of the material. Generally, an individual particle will only be in contact with the elevated temperatures for about 0.5 to about 20 seconds and preferably between about 0.5 to about 10 seconds.

The drying zone is preferably heated by injecting a heated gas such as hot air in the zone which also acts as a carrier to convey the particles to the quenching zone. Suitable flow rates for the heated gas are from about 6000 to about 15000 CFM for a 10-20 foot dryer. The flow rate can of course be scaled up or down depending upon the size of the dryer.

Preferred products of the present invention have densities between the range of about 2 to about 60 lbs/ft.sup.3 and preferably about 5 to about 25 lbs/ft.sup.3, and are used as color additives, flavor additives, bulking materials, sweetener compositions, and the like.

Next, the dried and blown beads are contacted with a cooled material which is gas at normal room temperature so as to quench cool the beads down to about room temperature or below and preferably to about 32.degree. F. or less. In a type of apparatus illustrated in FIG. 1, the quench cooling usually occurs in about 10 seconds or less, and preferably it takes from about 0.5 to about 8 seconds to cool the beads down to about room temperature or below. In a type of apparatus illustrated in FIG. 2, the quench cooling usually occurs in about 180 seconds or less, and preferably from about 10 to about 60 seconds. The time of the quench cooling in the type of apparatus illustrated in FIG. 2 is increased since a lesser volume of cooled gas contacts the particles as compared to the type of apparatus illustrated in FIG. 1. The cooling zone is preferably a liquified gas maintained at a temperature of between about 0.degree. and about 32.degree. F. and preferably about 0.degree. and about 22.degree. F. Suitable liquified gases include carbon dioxide and nitrogen under pressure of from about 200 to about 400 psi.

By quench cooling, the expansion of the beads is abruptly stopped so that the particle size and bulk density of the beads can be accurately controlled. Moreover, the strength of the walls in view of the quench cooling as opposed to merely permitting the beads to slowly cool at room temperature over an extended period of time are much harder and thereby resist crushing during shipment and resist vapor holes during the blowing operation.

Further advantage of the quench cooling is that the beads are maintained at elevated temperatures for reduced amount of time thereby flavors and sweeteners when used are much more concentrated than previously obtained due to the deleterious effect of heat upon flavors and sweeteners. Also, colors when employed are less apt to fade when subjected to reduced times at the elevated temperatures. After the beads are cooled, they can be collected by conveying them to conventional cyclones and stored.

In addition, heat sensitive edible materials such as vitamins, proteins, and flavors (e.g., in powdered form) can be added to the blown beads in the cooling zone to provide mixtures. For example, such can be added as powders or oils to the cooling zone through conduit (not shown) in the bottom portion 3 of FIG. 1 or into the screw conveyer of FIG. 2 via a conduit (not shown). This is advantageous since the heat sensitive materials are not subjected to any elevated temperatures. Also, the addition at this stage eliminates the need for a separate mixing step at some later time to provide a mixture of the blown bead and heat sensitive material. The rate of introduction of such heat sensitive edible material would be sufficient to provide the desired amount to be effective for its intended purpose.

The process of the present invention can be carried out in the types of equipment shown in FIGS. 1 and 2 wherein like numbers refer to the same elements. For instance, FIG. 1 illustrates a closed spray drying vessel 1 containing an upper portion 2 and a lower tapered portion 3. The flowable composition is sprayed into the upper portion 2 via lines 4 and nozzles 5. Heated gases such as heated air are introduced into the top portion 2 of the dryer via lines 6 through exits 8 to thereby contact the atomized material coming from the spray dryer 5 to promote expansion of the beads and drying of the particles. Cold liquified gas under pressure is introduced into the bottom portion 3 of the device via conduit 7 and spraying unit 9 to provide a zone for the quench cooling of the particles. The cooled particles then exit from the apparatus through outlet means 10. The beads can then be sent to cyclones (now shown) and then to storage.

FIG. 2 illustrates an apparatus similar to that illustrated in FIG. 1 except that the particles are quenched cooled in screw conveyer 20 which is attached to outlet 10. Cold liquified gas is injected at the outlet end of the screw conveyer 20 via conduit 21 to flow countercurrently to the expanded beads from unit 1 and to thereby quench cool the beads. The screw conveyer, if desired, can be jacketed (not shown) to provide further cooling means to the walls of the conveyer.

The following example is further presented to further illustrate the present invention.

An aqueous slurry containing about 264 gallons of water, about 1,875 pounds of maltodextrane, and about 6% by pressure weight of ammonium bicarbonate was spray dried in a 15 foot spray tower. The temperature of the composition is about 80.degree. F. as it enters the spraying apparatus. Heated air at a temperature of about 450.degree. F. is injected into the apparatus at a flow rate of about 10,000 CFM. Calculation of the overall average contact available by dividing the dryer volume by the air flow rate indicates a time of approximately 31/2 seconds in the heated zone. Next, the dried beads are contacted with a carbon dioxide atmosphere at about 0.degree. F. from liquified carbon dioxide supplied at a pressure of 300 psig. The beads are quenched cooled in about 5 seconds to about 10.degree.-20.degree. F. and exit the apparatus at about 10.degree.-20.degree. F. The product obtained has a bulk density of about 6 lb/ft..sup.3.