GB2258239A

GB2258239A - A process for removing fat from greaves

Info

Publication number: GB2258239A
Application number: GB9213221A
Authority: GB
Inventors: Thomas Noel Nicholas; Bernadette Nicholas; Michael John Mcdonagh
Original assignee: Marrow Research and Development Ltd
Current assignee: Marrow Research and Development Ltd
Priority date: 1991-07-29
Filing date: 1992-06-22
Publication date: 1993-02-03
Also published as: GB9213221D0; IE912653A1; BE1003156A6; IE69123B1

Abstract

Crushed animal bones are fed from a crusher (2) to a grinder (3) for mincing. The minced bone is delivered through a direct steam injection melt tube (5) for melting the fat into a first centrifugal separation decanter (6) where water and fat are centrifuged from the minced bone. Partly treated greaves with a fat content of 7% to 8% by weight of dry matter are delivered from the second decanter (6). Water at 70 DEG C is added to the partly treated greaves in a pipe (9) in the ratio of one part by volume water to two parts by volume of the partly treated greaves. The water/greaves mixture is pumped by a pump (11) into a second centrifugal separation decanter (12) where the fat content of the greaves is further reduced to produce finished greaves with a fat content of less than 1%. <IMAGE>

Description

A PROCESS FOR REMOVING FAT FROM GREAVES The present invention relates to a process for removing fat from greaves, for example, greaves produced from fresh animal bones.

It is known to produce protein and calcium phosphate from animal bones. In general, the fat content of calcium phosphate so produced is relatively high, and would commonly be over 3% by weight of the dry calcium phosphate. While such a fat content is acceptable where the calcium phosphate is for use in animal feed and horticultural proposes, such a relatively high fat content is unacceptable in calcium phosphate for use as health foods for human consumption and for pharmaceutical purposes. In general, calcium phosphate for use in health foods and in the pharmaceutical industry should have a fat content of not more than 2% by weight of the dry calcium phosphate, and preferably, less than 1% by weight of the dry calcium phosphate.

In the production of calcium phosphate from animal bones, fresh animal bones are chopped and ground and minced to produce greaves, the fat content of which is then reduced. The greaves are then subjected to a number of washing cycles where protein is washed from the greaves and the remaining greaves are further subjected to a separation process for separating meaty particles from the bone particles which are subsequently ground to form calcium phosphate. In general, it has been found that the fat content of the calcium phosphate produced using known processes and apparatus in general tends to be of the order of 3% by weight of dry matter of the calcium phosphate or more.

Attempts to produce calcium phosphate from fresh bones with a lower fat content have only had limited success. In general, such processes tend to be complex and accordingly, lead to relatively high production costs. It is believed that if the residual fat content of the greaves after the fat has been removed from the greaves could be reduced to levels lower than is normally practicable, the fat content of the calcium phosphate would be likewise reduced. It is believed that if the residual fat content of the greaves could be reduced to a level of not more than 2% by weight of dry matter, and preferably, to a level of not more than 1% by weight of dry matter, a calcium phosphate with a more desirably fat content could be produced.

Attempts have been made to treat greaves to reduce the fat content of the greaves to a level of not more than 2%, however, such attempts have been unsatisfactory.

Either the process employed failed to reduce the fat content of the greaves to the desired level, or alternatively, the cost of the process apparatus and the subsequent running costs of the process were unacceptably high.

There is therefore a need for a process for removing fat from greaves, and preferably, a process in which the fat content of the greaves after removal of the fat is not more than 2% by weight of the dry matter of the greaves. There is also a need for a process for producing calcium phosphate, protein and fat from the greaves.

The present invention is directed towards providing a process for removing fat from greaves. The invention is also directed towards providing a process for producing calcium phosphate, protein and fat from the greaves.

According to the invention there is provided a process for removing fat from greaves derived from crushed bone, the process comprising the steps of: heating the crushed bone to melt the fat, centrifuging the crushed bone and the melted fat in a first centrifugal separating decanter for separating some of the fat to produce partly treated greaves with a reduced fat content, adding water at a temperature of at least 600C to the partly treated greaves to form a water/greaves mixture, centrifuging the water/greaves mixture in a second centrifugal separating decanter for separating water and a substantial portion of the remaining fat from the water/greaves mixture to form finished greaves.

In one embodiment of the invention the fat content of the partly treated greaves is not more than 9% by weight of dry matter of the partly treated greaves, and the fat content of the finished greaves is not more than 2% by weight of the dry matter of the finished greaves.

Where it is desired that the fat content of the protein and or calcium phosphate should not exceed 1% by weight of day matter, the fat content of the finished greaves should be not more than 1% by weight of the dry matter of the finished greaves. Where it is desired that the fat content of the protein and calcium phosphate should be less than 1% by weight of dry matter, then the fat content of the finished greaves should be less than 1% by weight of the dry matter of the finished greaves.

Preferably the fat content of the partly treated greaves should be in the range of 5% to 9% by weight of dry matter of the partly treated greaves, and advantageously the fat content of the partly treated greaves should be in the range of 6% to 9% by weight of dry matter of the partly treated greaves.

In a preferred embodiment of the invention the fat content of the partly treated greaves is in the range of 7% to 8% by weight of dry matter by the partly treated greaves.

It has been found that good results are achieved when the temperature of the water added to the partly treated greaves is at least 650C, however, significantly better results are achieved when the temperature of the water added to the partly treated greaves is approximately 700C.

Preferably the proportion of water added to the partly treated greaves is in the range of one part by volume of water to three parts by volume of the partly treated greaves, to one part by volume of water to one part by volume of the partly treated greaves.

Advantageously, the proportion of water added to the partly treated greaves is approximately one part by volume of the water to two parts by volume of the partly treated greaves.

In a preferred embodiment of the invention the crushed bone is heated to melt the fat in a direct steam injection melt tube, and steam is delivered into the direct steam injection melt tube at a temperature in the range of 1000C to 1300C at a pressure in the range of one and a half bar to three bar, and preferably, the steam is at a temperature of 1000C at a pressure of three bar. Steam should be added at a rate sufficient to maintain the temperature of the heated crushed bone leaving the direct steam injection melt tube at a temperature of approximately 1000C.

Advantageously, the crushed bone is minced in a grinder prior to being delivered into the direct steam injection melt tube, and the minced bone is delivered through the direct steam injection melt tube into the first centrifugal separating decanter by the action of the grinder. Advantageously, the particle size of the minced bone leaving the grinder is not greater than 16 mm, and preferably, the particle size of the minced bone leaving the grinder is not greater than 13 mm.

To achieve these particle sizes, the grinder is provided with an orifice plate having a plurality of openings of size not greater than 16 mm in diameter, and preferably, the openings should be of diameter not greater than 13 mm.

Advantageously, the maximum particle size of the crushed bone prior to mincing is not greater than 40 mm, and preferably the maximum particle size of the crushed bones prior to mincing is not greater than 25 mm.

In one embodiment of the invention the greaves are derived from fresh animal bones, the waste produce of deboned meat.

In one embodiment of the invention the process further comprises the step of separating protein and calcium phosphate from the finished greaves.

Advantageously, the protein is washed from the finished greaves.

In another embodiment of the invention the calcium phosphate is dried in a rake drier, and preferably, the fat content of the calcium phosphate is not more than 2% by weight of the dried calcium phosphate.

Preferably, the fat content of the calcium phosphate is not more than 1% by weight of the dried calcium phosphate. Advantageously, the fat content of the calcium phosphate is less than 1% by weight of the dried calcium phosphate.

In a preferred embodiment of the invention the fat content of protein is not more than 2% by weight of the protein, preferably, the fat content of the protein is not more than 1% by weight of the protein, and advantageously the fat content of the protein is less than 1% by weight of the protein.

Additionally, the invention provides greaves produced using the process according to the invention.

Preferably, the greaves are produced using the process according to the invention with a fat content of the finished greaves of not more than 2% by weight of dry matter of the finished greaves, advantageously, the fat content of the finished greaves is not more than 1% by weight of the dry matter of the finished greaves, and advantageously the fat content of the finished greaves is less than 1% by weight of the dry matter of the finished greaves.

Further the invention provides fat removed from the greaves using the process according to the invention.

Further the invention provides protein separated from the greaves using the process according to the invention.

The invention also provides calcium phosphate separated from the greaves using the process according to the invention.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a block representation of part of process apparatus for carrying out the process according to the invention, Fig. 2 is a block representation of another part of the process apparatus for carrying out the process according to the invention, and Fig. 3 is a block representation of a further part of the process apparatus for carrying out the process according to the invention.

Referring to the drawings, there is illustrated process apparatus suitable for carrying out a process according to the invention for the production of greaves with a relatively low fat content, as well as for the production of calcium phosphate and protein of relatively low fat content, and fat from fresh animal bones. The animal bones would be of the type normally obtained fresh from boning halls as a waste product of deboned meat, and would normally have a residue of lean meat and fat. The bones may be used directly from the boning halls or may be deep frozen for storage prior to being processed. In this embodiment of the process according to the invention, finished greaves with a fat content of less than 1% by weight of dry matter of the finished greaves are produced.

In the process, the bones are delivered from a chill store 1 to a crusher 2 where the bones are crushed to a degree that the maximum particle size of the crushed bones is not greater than 25 mm.

The crushed bones are delivered from the crusher 2 by an auger 4 into a grinder 3 which grinds and minces the crushed bones to produce minced bone of particle size not greater than approximately 13 mm. The grinder 3 is provided with a orifice plate (not shown) having a plurality of circular openings all of 13 mm diameter to maintain the particle size of the minced bone at approximately 13 mm or less. The minced bone from the grinder 3 is delivered directly into, and heated in a direct steam injection melt tube 5 where the fat content of the minced bone is melted. The heated minced bone in a slush condition is delivered from the direct steam injection melt tube 5 into a first centrifugal separation decanter 6 where water and fat are separate from the minced bone.The water and fat are delivered through a pipeline 7 and collected in a holding tank 8, see Fig. 3 for subsequent separation of the water and fat, as will be described below. Minced bone in the form of partly treated greaves is delivered into a pipeline 9 from the first centrifugal separation decanter 6. The partly treated greaves are delivered from the first centrifugal separation decanter 6 with a fat content of between 7% and 8% by weight of the dry matter of the partly treated greaves. The grinder 3, direct steam injection melt tube 5 and the first centrifugal separation decanter 6 are so arranged that the action of the grinder 3 urges the minced bone delivered from the grinder 3 through the direct steam injection melt tube 5 and into the first centrifugal separation decanter 6 without the need for any other pumping action.Such grinders, direct steam injection melt tubes and centrifugal separation decanters will be well known to those skilled in the art. Steam at between 1000C and 1300C, and at a pressure of approximately three bar for melting the fat is delivered into the direct steam injection melt tube 5 at a rate sufficient to maintain the temperature of the heated minced bone leaving the direct stream injection melt tube 5 at a temperature of not less that 1000C.

Water at a temperature of approximately 700C is added to the partly treated greaves in the pipeline 9 at 10 for removing a substantial portion of the remaining fat from the partly treated greaves. The water is added in the ratio of one part by volume of water to two parts by volume of the partly treated greaves to form a water/greaves mixture. A pump 11 in the pipeline 9 delivers the water/greaves mixture into a second centrifugal separation decanter 12 which centrifuges the water and fat from the water/greaves mixture to separate the water and a substantial portion of the remaining fat from the water/greaves mixture. In this embodiment of the invention finish greaves are delivered from the second decanter 12 with a fat content of less than 1% by weight of the dry matter of the finished greaves.The second centrifugal separation decanter 12 is substantially similar to the first centrifugal decanter 6. Fat and water from the second decanter 12 is piped to waste through a pipeline 17, although, in certain circumstances, if desired, the fat and water could be collected for subsequent separation of the fat from the water. The finished greaves are delivered from the second centrifugal separation decanter 12 in an auger 14 for collection in a basket 16 of perforated metal. The basket 16 is used in an extraction cooker 20 for separating protein from the finished greaves, as will be described below with reference to Fig 2.

It has been found that, in general, the fat content of the finished greaves being delivered from the second centrifugal separation decanter 12 is in the order of 0.9% by weight of the dry matter of the finished greaves.

Referring to Fig. 2, the part of the process for producing protein and calcium phosphate will now be described. The extraction cooker 20 comprises a hollow sealed interior region within which the basket 16 is rotatably mounted for centrifuging the greaves after protein extraction. Such extraction cookers 20 will be well known to those skilled in the art, and it is not intended to describe the extraction cooker in further detail. The finished greaves in the basket 16 is placed in the cooker 20, and water at 1500C at 4 bar pressure is circulated through the cooker 20 by a pump 25 for washing the protein from the greaves. The wash water rich in protein is collected in a collection tank 26 and is subsequently delivered from the tank 26 into an evaporator 27, where the protein is dried to a moisture content of approximately 30% by weight of the protein.The protein produced is suitable as a soup stock for human consumption.

On substantially most of the protein having been washed from the greaves in the cooker 20, the pump 15 is de-energised and the cooker 20 is drained. The basket 16 is rotated to centrifuge the greaves, which are in turn delivered and collected in a storage vessel 30. The greaves are subsequently delivered to a rake drier 31 and heated to a temperature of between 1200C to 1600C and dried to a moisture content of less than 1% by weight of the greaves. The dried greaves which is now mainly constituted by calcium phosphate and relatively small meaty particles are temporarily stored in a batch holding tank 32. The greaves are then delivered from the holding tank 32 to a sieve 33 which separates the course particles from the fine particles.The course particles are constituted virtually entirely by calcium phosphate and these are delivered to a batch holding tank 34 for subsequent crushing in a mill 35 to a desired particle size. The crushed particles from the mill 35 are then delivered to a bagging plant 36 where they are packed in bags.

The fine particles from the sieve 33 which while being constituted largely by calcium phosphate-contain some meaty particles. The fine particles are passed by a magnet 37 for the removal of any metallic particles and into a mill 38 for crushing to a desired particle size. The crushed calcium phosphate from the mill 38 together with the meaty particles are delivered into a classifier grader 39 which separates out the meaty particles which are delivered to a storage tank 40 for subsequent bagging. The meaty particles may be subsequently used in animal feed preparations. The smaller calcium phosphate particles are delivered from the grader 39 into a batch holding tank 41 for subsequent transfer to silos 42 from which the calcium phosphate may be dispatched in bulk, or bagged in a suitable bagging plant.

Referring now to Fig. 3, the part of the process for separating the fat from the water will now be described. The fat and water mix in the holding tank 8 is delivered to a separator 50 where the water is extracted from the fat. The fat from the separator 50 is delivered into a drier 51 and subsequently delivered into a holding tank 52, from which the fat is subsequently filled and weight into suitable containers.

The advantages of the invention are many. It has been found that by producing finished greaves from the second decanter with a fat content of less than 1% by weight of dry matter, the fat content of the calcium phosphate produced from the mills 35 and 38 is less than 1% by weight of the dry matter of the calcium phosphate. Accordingly, the calcium phosphate produced using the process is suitable for health foods and other food stuffs for human consumption, as well as pharmaceutical and other purposes.

Furthermore, the fat content of the protein is also less than 1% by weight using the method of the invention just described.

It is believed that by adding water at a temperature of approximately 70 to the partly treated greaves and then centrifuging the water/greaves mixture in the second centrifugal separation decanter 12 surprisingly reduces the fat content of the partly treated greaves by approximately 6% to 7% by weight of dry matter, thereby reducing the fat content to less than 1% by weight of the dry matter of the finished greaves. It has been found that once the fat content of the finished greaves is at or less than 1% by weight of dry matter of the finished greaves, the fat content of the calcium phosphate and protein will likewise be less than 1% by weight of dry matter.Needless to say, if a slightly higher fat content was acceptable in the calcium phosphate and/or the protein, say, for example, up to 2% by weight of dry matter, then the fat content of the finished greaves could likewise be up to 2% by weight of the dry matter of the finished greaves.

It will be appreciated that while the process according to the invention also produces fat and protein, while this is advantageous, it is not essential.

Furthermore, it is not essential that meaty particles be collected from the greaves.

While the fresh animal bones have been subjected to crushing and grinding as separate operations, in certain cases, it is envisaged that the grinding and crushing step of the process may be carried out in a crusher/grinder apparatus. It will also be appreciated that other suitable means for heating the greaves for melting the fat may be used besides a direct steam injection melt tube.

While the bones have been described as fresh animal bones, it will be appreciated that bones from cold storage may be used, if desired.

Claims

1. A process for removing fat from greaves derived from crushed bone, the process comprising the steps of: heating the crushed bone to melt the fat, centrifuging the crushed bone and the melted fat in a first centrifugal separating decanter for separating some of the fat to produce partly treated greaves with a reduced fat content, adding water at a temperature of at least 600C to the partly treated greaves to form a water/greaves mixture, centrifuging the water/greaves mixture in a second centrifugal separating decanter for separating water and a substantial portion of the remaining fat from the water/greaves mixture to form finished greaves.

2. A process as claimed in Claim 1 in which the fat content of the partly treated greaves is not more than 9% by weight of dry matter of the partly treated greaves, and the fat content of the finished greaves is not more than 2% by weight of the dry matter of the finished greaves.

3. A process as claimed in Claim 2 in which the fat content of the finished greaves is not more than 18 by weight of the dry matter of the finished greaves.

4. A process as claimed in Claim 3 in which the fat content of the finished greaves is less than 1% by weight of the dry matter of the finished greaves.

5. A process as claimed in any of Claims 2 to 4 in which the fat content of the partly treated greaves is in the range of 5% to 9% by weight of dry matter of the partly treated greaves.

6. A process as claimed in Claim in which the fat content of the partly treated greaves is in the range of 6% to 9% by weight of dry matter of the partly treated greaves.

7. A process as claimed in Claim 6 in which the fat content of the partly treated greaves is in the range of 7% to 8% by weight of dry matter of the partly treated greaves.

8. A process as claimed in any preceding claim in which the temperature of the water added to the partly treated greaves is at least 650C.

9. A process as claimed in Claim 8 in which the temperature of the water added to the partly treated greaves is at least 700C.

10. A process as claimed in any preceding claim in which the proportion of water added to the partly treated greaves is in the range of one part by volume of water to three parts by volume of the partly treated greaves, to one part by volume of water to one part of the partly treated greaves.

11. A process as claimed in Claim 10 in which the proportion of water added to the partly treated greaves is approximately one part by volume of water to two parts by volume of the partly treated greaves.

12. A process as claimed in any preceding claim in which the crushed bone is heated to melt the fat in a direct steam injection melt tube.

13. A process as claimed in Claim 12 in which the steam is delivered into the direct steam injection melt tube at a temperature in the range of 100"C to 1300C and at a pressure in the range of 1.5 bar to 3 bar.

14. A process as claimed in Claim 13 in which the steam is delivered into the direct steam injection melt tube at a temperature of approximately 1000C at a pressure of approximately 3 bar.

15. A process as claimed in any of Claims 12 to 14 in which the quantity of steam delivered to the direct steam injection melt tube is regulated to maintain the temperature of the heated crushed bone leaving the direct steam injection melt tube at a temperature in the range of approximately 1000C.

16. A process as claimed in any preceding claim in which the crushed bone is minced in a grinder prior to being delivered into the direct steam melt tube.

17. A process as claimed in Claim 16 in which the minced bone is delivered through the direct steam injection melt tube into the first centrifugal separating decanter by the action of the grinder.

18. A process as claimed in Claim 16 or 17 in which the particle size of the minced bone from the grinder is not greater than 16 mm.

19. A process as claimed in any of Claims 18 in which the particle size of the minced bone leaving the grinder is not greater than 13 mm.

20. A process as claimed in any of Claims 16 to 19 in which the grinder for mincing the bones comprises an orifice plate having a plurality of openings of size not greater than 16 mm diameter.

21. A process claimed in claim 20 in which the openings of the orifice plate are not greater than 13 mm diameter.

22. A process as claimed in any of Claims 16 to 21 in which the maximum particle size of the crushed bone prior to mincing is not greater than 40 mm.

23. A process as claimed in Claim 22 in which the maximum particle size of the crushed bone prior to mincing is not greater than 25 mm.

24. A process as claimed in any proceeding claim in which the greaves are derived from fresh animal bones, the waste produce of deboned meat.

25. A process as claimed in any proceeding claim in which the process further comprises the step of separating protein and calcium phosphate from the finished greaves.

26. A process as claimed in Claim 25 in which the protein is washed from the finished greaves.

27. A process as claimed in Claim 25 or 26 in which the calcium phosphate is dried in a rake drier.

28. A process as claimed in any of Claims 25 to 27 in which the fat content of the calcium phosphate is not more than 2% by weight of the dried calcium phosphate.

29. A process as claimed in Claim 28 in which the fat content of the calcium phosphate is not more than 1% by weight of the dried calcium phosphate.

30. A process as claimed in Claim 29 in which the fat content of the calcium phosphate is less than 1% by weight of the dried calcium phosphate.

31. A process as claimed in Claim 25 or 26 in which the fat content of the protein is not more than 2% by weight of the protein.

32. A process claimed in Claim 31 in which the fat content of the protein is not more than 1% by weight of the protein.

33. A process as claimed in Claim 32 in which the fat content of the protein is less than 1% by weight of the protein.

34. A process for removing fat from greaves, the process being substantially as described herein with reference to and as illustrated in the example.

35. Greaves produced according to the process of any of Claims 1 to 34.

36. Greaves as claimed in Claim 35 in which the fat content of the finished greaves is not more than 2% by weight of the dry matter of the finished greaves.

37. Greaves as claimed in Claim 36 in which the fat content of the finished greaves is not more than 1% by weight of the dry matter of the finished greaves.

38. Greaves as claimed in Claim 37 in which the fat content of the finished greaves is less than 1% by weight of the dry matter of the greaves.

39. Fat removed from the greaves according to the process of any of Claims 1 to 34.

40. Protein separated from the greaves according to the process of any of Claims 25 to 34.

41. Calcium phosphate separated from the greaves according to the process of any of Claims 25 to 34.