Agglomerating granular material

[57] ABSTRACT

An agglomerating technique in which a formulation containing a major amount of granular materia! and a minor amount of powdered material is throughly blended and fed through an agglomerator. This method provides a means for adjusting and controlling the bulk density of agglomerated products over ranges not readily obtained when agglomeration is performed with all powdered material.

Claims, No Drawings

3,660,108

AGGLOMERATING GRANULAR MATERIAL BACKGROUND OF THE INVENTION

Processes for agglomerating powders for the purposes of improved dispersibility, decrease in bulk density, and other characteristics are well known and are disclosed in many prior art patents such as U.S. Pat. Nos. 3,011,897, 3,143,428, and 3,485,637. These prior art patents indicate that one requirement for good agglomeration is the need for the small particle size of all of the feed materials. It is generally thought that the finer the size of the feed materials the more successful will be the agglomeration. The reasoning for this assumption is that the fine particles have a greater surface area per unit weight than the coarser particles and, therefore, will offer more contact points for wetting and subsequent agglomeration. It has been assumed that agglomeration utilizing granular material will not be practical.

This invention shows that with the proper selection of granular and powdered materials agglomerated products hav- . ________a____ ing improved characteristics and flexibility of their properties ²⁰ bodiments of this invention, can be achieved. - .....

Some problems which have arisen in the prior art with the agglomeration of all powdered feed materials have been difficulties in handling and conveying the powdery materials, a relatively high content of fine particles in the final product, and a relatively limited amount of flexibility in varying a bulk density of the final agglomerated product.

SUMMARY

This invention utilizes feed material containing a major amount of granular particles to achieve agglomerated products and overcomes the disadvantages of using large quantities of powdery feed materials. The invention relates more particularly to the agglomerating of food particles to 35 achieve a free-flowing product whose bulk density may be precisely controlled.

According to this invention granular materials are employed in the formulation of agglomerated products and the proper selection of the granular materials presents a new tool 40 in achieving product characteristics not otherwise readily obtained. This invention utilizes powdery materials to act as binding agents for securing together the granular particles. It is contemplated according to this invention that agglomerated products comprising of up to about 85 percent granular 45 material may be produced. As will be seen, this invention finds use in the formulation of low calorie sugar substitutes, powdered beverage products, and soluble coffee products.

It is an object of this invention to produce agglomerated materials having a low level of fine material.

It is another object of this invention to be able to control the bulk density of an agglomerated material.

It is also an object of this invention to eliminate a large percent of powdered feed material in agglomeration processes.

These and other objects of this invention will become ap- 55 parent from the description herein.

DESCRIPTION OF THE INVENTION

In this invention agglomerated products, especially food products, are produced by employing feed materials compris- 60 ing a major amount of granular material with a minor amount of powdered material. According to this invention the feed materials may include from 50 percent up to about 85 percent of the granular material and preferably from 70 to 85 percent granular material.

As used in this invention granular material is meant to include materials in which at least 50 percent by weight will be retained on a 50 mesh screen (all meshes U.S. Standard Sieves) and/or in which at least about 90 percent will be retained on a 70 mesh screen and preferably in which essentially all the material is at least 200 microns in size.

The powdered material of this invention encompasses those powders in which essentially all the particles are less than 100 microns and preferably in which at least about 95 percent by weight will pass through a 200 mesh screen.

The concept of this invention utilizes the amount and size of the granular material to produce agglomerated products with certain desired physical characteristics such as bulk density. In addition, this invention employs powdery material to act as a “cement” between the larger granular particles and to produce strong and attractive agglomerates. It is possible to produce the agglomerates of this invention by using powdery materials. For instance, a readily dispersible sweetener can be produced using granular sugar and powdered sugar or a powdered beverage mix can be produced using granular food acid and powdered sweeteners.

A preferred embodiment of this invention is the agglomeration of granular freeze-dried coffee with a powdered soluble coffee.

Freeze-dried coffee has met with wide consumer acceptance since it possesses many flavor advantages over the heretofore widely used spray-dried coffee. However, some problems have arisen with the use of freeze-dried coffee and these problems are sought to be overcome by one of the emit has been found that freeze-dried coffee possesses a rather light color which has not met with wide consumer appeal. Through the method of this invention granular freeze-dried coffee may be agglomerated with powdered soluble coffee and the color of the resultant coffee agglomerates will tend to be darker than the color of the freeze-dried granules. These agglomerate coffee clusters also possess a mottled surface similar in appearance to that of freshly ground roasted coffee.

Freeze-dried coffee has also met with the problem of many fine particles that occur either in the original processing or subsequently develop from the breakage of the freeze-dried particles. These fine particles tend to accumulate at the bottom of a container (e.g', glass jar) of freeze-dried coffee and present an unappealing appearance to the consumer. Through the method of agglomerating freeze-dried coffee with soluble coffee powder the fine freeze-dried particles can be substantially eliminated.

In this agglomeration process the small particles of soluble coffee powder, such as spray-dried coffee, tend to act as the cementing medium to bind together the particles of freezedried coffee. These agglomerated coffee particles possess good structural stability and appear to reduce the problem of breakage of the freeze-dried coffee particles.

It has been found that the incorporation of up to 30 percent by weight of the spray-dried coffee with at least about 70 percent by weight of freeze-dried coffee does not noticeably detract from the excellent flavor normally associated with 100 percent freeze-dried coffee. This coffee product also possesses economic advantages since the less costly spray-dried coffee 50 can be substituted in part for the more expensive freeze-dried coffee.

In this embodiment of the invention the particles of spraydried coffee of less than 100 microns in size are employed. These particles are usually obtained by grinding regular spraydried coffee solids (about 100 to 300 microns) in a commercial mill (e.g., Fitz Mill); however, any procedure which will produce spray-dried coffee solids having essentially all the particles less than 100 microns in size may be employed.

The composite granular and powdered feed material employed in this invention is agglomerated in any of the prior art agglomerating equipment operating under conditions which will be readily apparent to one skilled in the art.

This invention is further described but not limited by the following examples.

EXAMPLEI

A dry mix of the following formulation is throughly mixed in a ribbon mixer.

Granular Sized Material: Weight %

Fine Granular Sugar 83.72 (less than 7% on 20 mesh, more than 35% cumulative on 40 mesh, less than 15% through 70 mesh) '5 Powdered Sized Material:

3,660,108 the product of this example was able to achieve the desired bulk density, was lower in fines content, and had better color development.

EXAMPLE ΠΙ

Corn Syrup Solids, 24 D.E.14.80 (Frodex)

Sodium Cyclamate1.14

Sodium Saccharin0.114

Salt0^210

Carboxymethylcellulose (CMC)0.016

This feed mix (0.82 g/cc) is agglomerated in a standard commercial agglomerates (Blaw-Knox Series 750 Instantizer) with a steam inlet temperature of 225° F. and a drying air temperature of 265° F. The agglomerated product (0.28 g/cc) exhibited a marked improvement in particle appearance (e.g., more table sugar-like) and reduction in fines content over a sample produced from a feed, of identical composition but in a completely powdered condition, agglomerated under similar conditions. It was found that fines (i.e., those particles through a 200 mesh screen) were present in the agglomerated products of this example in the amount of only 0.8 percent; whereas, when the all powdered feed material was agglomerated the fines amounted to 16.9 percent of the final product.

Spray-dried coffee having a particle size distribution of between 100 and 300 microns is ground in a hammer mill (Fitzpatrick Model D/6, equipped with a 4 mesh screen) to produce a powder wherein at least 95 percent of the particles were less than 50 microns in size. This ground spray-dried coffee is throughly mixed in a ribbon blender in accordance with the following formulation.

Granular Material: Weight %

Granular Freeze-Dried 70.5

Coffee (at least 50% on 30 mesh less than 20% through 50 mesh)

Powdered Material:

Spray-Dried Coffee 29.5 (ground in hammer mill)

EXAMPLE II

A dry beverage mix with the formulation shown below and with a final screened bulk density of 0.50 g/cc was required to meet package fill specifications. This could not be achieved by agglomerating a mix containing ground citric acid because too low a density resulted. The density specification could only be met by using a fine granular citric acid in the feed as shown below.

<td> Granular Material:</td><td> Weight %</td>

<td> Fine Granular Citric Acid (anhydrous) (at least 50% on 40 mesh) Powdered Material:</td><td> 66.255</td>

<td> Dextrose (2001 Cerelose)</td><td> 13.597</td>

<td> Com Syrup Solids, 24 D.E. (Frodex)</td><td> 13.597</td>

<td> Corn Starch</td><td> 4.907</td>

<td> Lemon Solids</td><td> 0.038</td>

<td> Color-Flavor Agents</td><td> 1.606</td>

This mix is blended for 5 minutes in a V-blender and the feed (0.87 g/cc) is agglomerated in a standard commercial agglomerator with a steam inlet temperature of 225° F. and a drying air temperature of 230° F. The agglomerated product (0.27 g/cc) was screened through a 16 mesh screen to achieve the desired bulk density of about 0.50 g/cc. This product exhibited advantages over the all-powder feed method in that

This mix is agglomerated in a standard commercial agglomerator with a steam inlet temperature of 225° F. and a drying air temperature of 425° F. The agglomerated product presented an appearance more similar to ground roasted coffee than the normal freeze-dried coffee and the product of this example produced a coffee beverage rated equal in flavor to the 100% freeze-dried coffee beverage.