Method for reforming dairy products

BACKGROUND OF THE INVENTION

The invention relates generally to dairy products, and particularly to methods and apparatus for reforming cheese products and other dairy products.

In the manufacture of chunk cheese products, large blocks of natural cheese weighing on the order of about 600 to 700 lbs. are divided into smaller chunks for retail sale. Parts of the large blocks are left as irregularly shaped pieces, referred to as trim or offcuts.

In the past, such pieces have often been used as ingredients for process cheese, or have been formed into shreds. However, the value of the resulting product, be it shredded cheese or process cheese, is generally lower than the value of blocks or chunks of natural cheese. Substantial effort has been devoted to developing methods for reforming such pieces into larger blocks of natural cheese. It is believed that combining small pieces into a cohesive larger chunk requires a certain amount of working of the cheese. Without sufficient working, the end product may not be cohesive, i.e., the chunk may have visible divisions, and may separate along such divisions or crumble when sliced or otherwise handled by the consumer. Excessive working, however, results in “oiling off”, i.e., separation of oil, and/or maceration, resulting in an unacceptable end product. One aspect of the invention is to provide a method and apparatus for reforming small cheese pieces such as trim or offcuts, and/or other dairy products, into chunks of natural cheese, or into other solid, cohesive dairy products of firm texture, without maceration or separation of oil.

Ross, U.S. Pat. No. 3,727,308, discloses apparatus for reconstituting cheese trimmings into a solid block. Cheese trimmings are placed in a hopper and forced through holes in a plate under the action of an auger and knife.

Sadler, U.S. Pat. No. 4,382,969, discloses a method for treating cheese off-cuts wherein the off-cuts are first cut into small chips, and then pressed in an evacuated environment to form a reconstituted block of cheese. Sadler states that the apparatus described in the above-discussed Ross patent has several drawbacks in that the displacement of the trimmings using a helical auger results in considerable working of the cheese which can detract from the characteristics of the end product. The apparatus of Sadler employs a ram, rather than an auger, to advance the cheese. In Sadler, the cheese undergoing processing remains in the range of 8° C. to 12° C. This temperature control is achieved, if necessary, by including a cooling jacket around the nozzle

32

at the outlet end of the equipment.

U.S. Pat. No. 4,185,126, discloses a process of reconstituting cheese trimmings into horns by grinding the trimmings into a particulate mass at a temperature which inhibits bacteria growth, then ramming the particulate mass into a closed mold.

Runge et al., U.S. Pat. No. 3,562,910, discloses a method for manufacture of natural cheese from curd. The Runge apparatus includes a curd transfer device that includes a pair of co-acting helical cams and a close fitting housing therefor. The helical cams are shown as intermeshing. In the Runge patent, the cams force the curd into a forming tube to establish knitting. The tube appears to be of uniform circular cross-section. Its length is about 5 feet to 20 feet. Heating of the tube to a temperature sufficient to melt the fat of the cheese curd is said to cause oiling off which effects lubrication of the walls of the tube and lowers the effective resistance of the tube. This patent states that undue oiling off is undesirable, and that the temperature of the tube surface adjacent to the cheese should not exceed about 160° F.

Miller et al., U.S. Pat. No. 4,620,838, assigned to Kraft, Inc., discloses use of a ram for forcing cheese through a perforated die plate to form shreds.

U.S. Pat. No. 5,768,970 discloses an ultrasonic cutting system for cutting of foodstuffs including cheese.

It is a general object of the invention to provide a novel and improved method and apparatus for reforming small pieces of cheese or other dairy product into larger chunks with appearance, taste and texture similar to fresh cut natural chunks or other products having enhanced value.

SUMMARY OF THE INVENTION

In accordance with the invention, a method and apparatus for reforming small pieces of natural cheese or other dairy products, such as shreds, trim, or offcuts, are provided wherein the small pieces are fed through a mechanical pump and a die that form the product into a cohesive larger chunk. The mechanical pump and the die preferably operate such that natural cheese pieces may be formed into the larger chunk of natural cheese having a very similar texture and appearance to that of the original product.

In a preferred embodiment of the invention, the mechanical pump mixes and folds the small pieces of cheese or other dairy products into a viscous mass without excessive separation of oil. More particularly, the mechanical pump in the preferred embodied produces a viscous mass with virtually no separation of oil. Any oil that does separate from the product is of a minimal amount, e.g., less than 0.1% of the oil in the cheese pieces. The mechanical pump then feeds the viscous mass through the die. The die preferably has a region of substantially uniform cross-section. The ratio of the length of the region to its smallest cross-sectional dimension, e.g., its height, is preferably about 4:1. The region of substantially uniform cross-section is maintained at an elevated temperature to reduce drag and improve the appearance of the end product.

The method and apparatus of the invention preferably enables offcuts, trim and other small pieces of natural cheese or other dairy products to be reformed into cohesive larger chunks of natural cheese, without addition of water, salt or other ingredients, and without separation of oil or maceration. The configuration and speed of operation of the mechanical pump are selected so that it does not overwork the smaller pieces when mixing and folding them into a viscous mass. The substantially uniform region of the die forms the viscous mass into the desired shape with well defined edges. The die temperature reduces friction and produces a thin surface seal about the exterior surface of the larger chunk without excessive separation of oil from the surface of the larger chunk.

In the preferred embodiment of the invention, the extrudate is fed through one or more slitting and cutting stations after emerging from the die. The slitting and cutting stations preferably use ultrasonic cutters to leave clean, smooth, sealed edges with no fines and a thin surface seal to minimize moisture or volatile losses as well as enhance the product appearance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is an elevational view of apparatus for reforming pieces of natural cheese or other dairy products into cohesive larger chunks in accordance with a first embodiment of the invention.

FIG. 2

is a plan view of the mechanical pump and die of FIG.

1

.

FIG. 3

is an elevational view of the mechanical pump and die of FIG.

2

.

FIG. 4

is a perspective view of the die of FIG.

2

.

FIG. 5

is a sectional view taken substantially along lines

5

—

5

in FIG.

3

.

FIG. 6

is a sectional view taken substantially along lines

6

—

6

in

FIG. 2

FIG. 7

is an sectional view illustrating a die half in accordance with a second embodiment of the invention.

FIG. 8

is an end view of the die half of FIG.

7

.

FIG. 9

is a perspective view of the die of the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is preferably embodied in a method and apparatus for reforming pieces of natural cheese or other dairy products

1

into cohesive chunks or bars

7

. A preferred embodiment of the invention, wherein small pieces of natural cheese

1

such as trim or offcuts are reformed into bars

7

for retail sale is disclosed below

FIG. 1

illustrates apparatus for reforming small pieces of natural cheese or other dairy products

1

into cohesive larger chunks

7

. The small pieces of cheese or other dairy products

1

are placed in an intake bin

10

adjacent to a mechanical pump

20

. Located above the mechanical pump

20

is a hopper

21

for feeding the small pieces

1

into the mechanical pump

20

. A conveyor

15

between the intake bin

10

and the hopper

21

transfers the small pieces

1

from the intake bin

10

to the hopper

21

.

After entering the hopper

21

, the small pieces

1

enter the mechanical pump

20

, where they are mixed and folded together without any visible separation of oil, then formed by a die

30

into a continuous sheet

5

of predetermined cross-section. The continuous sheet

5

exits the die

30

onto a conveyor

60

. The conveyor

60

moves the sheet

5

past a slitting station

40

where the sheet

5

is separated into longitudinal strips

6

, then to a cross cutting station

50

where the strips

6

are cut into cheese bars

7

. The conveyor

60

then moves the cheese bars

7

to a delivery station.

In the preferred embodiments of the invention, the mechanical pump

20

has a pump chamber

22

that is fed by the hopper

21

as illustrated in FIG.

3

. Inside the pump chamber

22

are two non-intermeshing augers

25

as illustrated in

FIGS. 2 and 3

. The rotation of the augers

25

mixes and folds the small pieces of cheese or other dairy products

1

while forcing them through the die

30

. In one particular embodiment of the invention, the pump

20

may comprise a commercially available pump, Polar Pump Model

352

, manufactured by Polar Process Incorporated of Plattsville, Ontario. Each of the augers

25

preferably has an outer diameter of between 3 and 4 inches, an inner diameter or shaft diameter of between 1 and 2 inches, and a pitch of between 3 and 4 inches. The augers are preferably rotated at a rate less than 21 rpm. The rate of rotation is preferably between 7 rpm and 21 rpm.

The die

30

comprises a compressing die portion or transition section

31

and a forming die portion

35

as illustrated in FIG.

4

. The compressing die portion

31

narrows from a compressing die intake end or mouth

32

to a compressing die outlet

33

. Attached to the compressing die outlet

33

is the forming die

35

. The forming die

35

has a narrowing section

36

and a straight section

37

as illustrated in FIG.

6

. The narrowing section

36

decreases in cross-section toward the straight section

37

preferably from 10 by 1 inches to 8 by 0.50 inches as illustrated in FIG.

5

. The straight section

37

has a substantially uniform cross-section. The ratio of the length of the straight section

37

to its smallest cross-sectional dimension may be at least 2:1 and less than 6:1, and may be between 3:1 and 5:1. In the preferred embodiment, the ratio is 4:1.

Both the compressing die

31

and the forming die

35

have drilled internal passages

38

for the circulation of fluid around each die

31

and

35

as illustrated in

FIGS. 4-6

. The flow of fluid through the passages

38

allows for the dies

31

and

35

to be maintained at a desired temperature The desired temperatures in preferred embodiments of the invention are between 85° and 100° F. The desired temperature can also be between 85° and 95° F. and between 88° and 92° F. The provision of drilled internal passages

38

, rather than a water jacket, is believed to provide a more reliable means of controlling and maintaining a uniform temperature without leakage of heat transfer fluid.

In a second embodiment of the invention, a combination die

70

, illustrated in

FIGS. 7-9

, replaces the compressing die

31

and forming die

35

. The combination die

70

has a circular mouth

71

that conically narrows and transitions to a rectangular straight section

72

. The combination die

70

has internal passages

73

for the flow of fluid around the die

70

. The flow of fluid through the passages

73

allows the die

70

to be maintained at a desired temperature. The desired temperatures in preferred embodiments of the invention are between 85° and 100° F. The desired temperature can also be between 85° and 95° F. and between 88° and 92° F. In the preferred embodiments of the invention, the slitting station

40

comprises seven ultrasonic slitting horns vibrating at 20 kHz. The slitting horns are spaced one inch apart. The cutting station

50

comprises an ultrasonic guillotine horn. The guillotine horn is twelve inches long. In one particular embodiment of the invention, the ultrasonic horns for the slitting station

40

and the cutting station

50

are manufactured by Dukane Corporation of St. Charles, Ill.

EXAMPLE 1

Natural shreds of mild cheddar cheese

1

are fed into the hopper

21

located above the mechanical pump

20

so that the shreds form a bed in the pump chamber

22

with a depth of about 2 to 4 inches from the uppermost edges of the augers

25

. A forming die

35

with an 8 by ½ inch opening is attached to the exit end of the mechanical pump

20

. The forming die

35

is equipped with a hot water re-circulating jacket and water is circulated through the jacket at a temperature of 91° F. The augers

25

of the mechanical pump

20

are operated at 7 rpm to gently mix, knead, and compact the shreds

1

into the forming die

35

. The shreds

1

are shaped by the forming die

35

and exit the die

35

in a continuous sheet

5

. The reformed cheese product

7

has a smooth surface finish and well defined edges. The product appearance and sensory attributes are very much like those of fresh cut natural chunks. The throughput rate is about 285 lb/hr.

EXAMPLE 2

Natural shreds of mild cheddar cheese

1

are reformed into a continuous sheet of cheese

5

in a similar manner as in EXAMPLE 1. Ultrasonic horns of the slitting station

40

and the cross-cutting station

50

, operating at a frequency of 20 kHz, then cut the sheet

5

into 1 by 3 by ½ inch bars

7

. The ultrasonic horns leave the edges of the bars

7

clean and smooth with no fines. The ultrasonic horns also give the cut surfaces a thin compression seal which minimizes moisture or volatile losses and enhances the appearance of the bars

7

. The frequency of the ultrasonic horns also destroys vegetative cells that may reside on the horns, thus minimizing the risk that microbial contaminants will be carried from one bar to the next.

EXAMPLE 3

Natural shreds of mild cheddar cheese

1

are reformed into cheese bars

7

in a similar manner as in EXAMPLE 2, except that the pump speed is increased from 7 rpm to 14 rpm. The throughput rate is about 525 lb./hr. The product density is approximately 0.620 oz/in

3

(1.08 g/cc). The appearance, texture, and sensory attributes of the bars

7

are like fresh cut natural cheddar chunks.

EXAMPLE 4

Natural shreds of mild cheddar cheese

1

are mixed with approximately 4% calcium sulfate dihydrate powder in a tumbling drum, obtaining an essentially uniform distribution of powder on the cheese shreds

1

. The cheese shreds

1

are then reformed into cheese bars

7

in a similar manner as in EXAMPLE 3. The product density is approximately 0.650 oz/in

3

(1.13 g/cc). The appearance, texture, and sensory attributes of the bars

7

are like fresh cut natural cheddar chunks.

EXAMPLE 5

Natural shreds of mild cheddar cheese

1

are reformed into a continuous sheet of cheese

5

in a similar manner as in EXAMPLE 1, except that the pump speed is increased from 7 rpm to 21 rpm. The cheese sheet

5

shows a thin film of oil on the surface. The cheese sheet texture was soft and creamy. This indicates that the cheese has undergone shear thinning and breakdown of curd leading to a soft, creamy texture similar to processed cheese. The cheese sheet

5

is noticeably different from fresh cut natural cheese chunks.

From the foregoing, it will be appreciated that the invention provides a method and apparatus for reforming pieces of natural cheese or other dairy products into cohesive chunks or bars. The invention is not limited to the embodiments described hereinabove or to any particular embodiments. Various additional steps may be combined with the processes described above. For example, herbs, spices, vitamins, calcium or other minerals may be added to the reformed cheese bars in a similar manner as the calcium sulfate dehydrate described in EXAMPLE 4.

The invention may be embodied in processes for generating end products of various sizes and shapes, including but not limited to snack cubes, e.g., ⅝ in. cubes, bars of triangular cross section, wedges, rings, stars, and 5.6 by 2.2 by 1.6 inch, eight ounce chunks or larger reformed chunks.

The invention is defined more particularly by the following claims.