METHOD OF PRODUCING A LOW-FAT PRODUCT AND A SYSTEM FOR PRODUCING A LOW-FAT PRODUCT

Abstract

A method of producing a low-fat product from a starting material made of a fat and/or oil containing plant- or animal item includes providing the starting material at a temperature of at least 35° C. and extracting a greater part of the extractable oil and/or fat originally contained in the plant or animal item from the starting material using a first decanter centrifuge. The first decanter centrifuge leaves a residue of solids and liquids. The residue forms the low-fat product.

Claims

1. A method of producing a low-fat product from a starting material, the method comprising: providing the starting material at a temperature of at least 35° C., the starting material comprising a plant or animal item, said plant or animal item comprising fat and/or oil; and extracting a greater part of extractable oil and/or fat contained in the plant or animal item from the starting material using a first decanter centrifuge, thereby leaving a residue of solids and liquids, the residue forming the low-fat product.

2. The method according to claim 1, wherein the item comprises palm fruit, fish, meat or krill.

3. The method according to claim 1, wherein the starting material is provided at a temperature of between 40° C. and 142° C.

4. The method according to claim 1, wherein the starting material is pumpable and/or wherein the starting material is provided in an aqueous solution.

5. The method according to claim 1, wherein the first decanter centrifuge is of a two-phase type.

6. The method according to claim 1, further comprising: dewatering the low-fat product using a dewatering apparatus.

7. The method according to claim 6, wherein the dewatering apparatus is a second decanter or a belt press.

8. The method according to claim 6, wherein the dewatering apparatus is a second decanter, wherein the first decanter defines a first bowl and a first conveyor rotating with a first differential speed therebetween, wherein the second decanter defines a second bowl and a second conveyor rotating with a second differential speed therebetween, and wherein the first differential speed is higher than the second differential speed.

9. The method according to claim 8, wherein the first differential speed is between 25 rpm and 75 rpm, and the second differential speed being between 1 rpm and 25 rpm.

10. The method according to claim 1, wherein the first decanter defines a first large end hub, a first small end hub located opposite the first large end hub, a first central axis extending between the first large end hub and the first small end hub, a first light phase discharge located at the first large end hub and defining a first liquid level, and a first heavy phase outlet located at the first small end hub, and wherein the first heavy phase outlet is located substantially at the first liquid level.

11. The method according to claim 10, wherein an infeed for the starting material is located adjacent the first large end hub.

12. The method according to claim 1, wherein the first decanter comprises a baffle for directing the flow inside the first decanter.

13. The method according to claim 1, wherein the item has a solid content of at least 5%.

14. The method according to claim 1, wherein the starting material is heated by a steam heater.

15. A system for producing a low-fat product from a starting material, the system comprising: a heater for heating the starting material to a temperature of at least 35° C., the starting material comprising a plant or animal item, said plant or animal item comprising fat and/or oil; and a first decanter centrifuge for extracting a greater part of extractable oil and/or fat contained in the plant or animal item from the starting material and leaving a residue of solids and liquids, the residue forming the low-fat product.

16. The method according to claim 1, wherein the starting material is provided at a temperature of between 60° C. and 120° C.

17. The method according to claim 1, wherein the starting material is provided at a temperature of between 80° C. and 100° C.

18. The method according to claim 5, wherein the first decanter centrifuge is of the leading conveyor style.

19. The method according to claim 8, wherein the first differential speed is between 30 rpm and 50 rpm, and the second differential speed being between 5 rpm and 15 rpm.

20. The method according to claim 1, wherein the item has a solid content between 5-50%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] FIG. 1 shows a setup according to the present invention.

[0055] FIG. 2 shows a first decanter centrifuge according to the present invention.

[0056] FIG. 3 shows a second decanter centrifuge according to the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0057] FIG. 1 shows a decanter setup 10 for producing a fat reduced product from an item according to the present invention. The item comprising oily organic material is first heated in a steam heater 12. The item may be plant material such as whole or parts of palm fruit, or it may be animal material such as fish or krill or part of fish such cod liver. It may also be other animal material such as edible wet rendered lard or tallow. The item is received at an inlet 14 of the steam heater 12 and is fed to an outlet 16 of the steam heater 12. The item is thereby exposed to steam via a steam injector 18 and the temperature of the item is elevated to about 92-95° C. This causes the cell walls of the item to break down into an oily phase, a water phase and solids. In the next steps, the oily phase, the water phase and the solids are separated. It should thereby be ensured that the solid material contains as little oil as possible in order to achieve a fat reduced solid product.

[0058] The heated item is introduced into a first decanter centrifuge 20 via an inlet 22. The first decanter centrifuge 20 separates the heated item into a slurry containing solids and water. The slurry is discharged at a slurry outlet 24, and the oily phase containing oil and/or fat is discharged at an oil phase outlet 26.

[0059] The slurry is introduced into a second decanter centrifuge 28 via a slurry inlet 30. The second decanter centrifuge 28 separates the heated item into a solid phase which is discharged at a solid outlet 32, and a liquid phase which is discharged at a liquid outlet 34. The solid material containing mostly fibre and protein from the item and an effluent phase containing mostly water from the item.

[0060] Optionally, the effluent obtained from the liquid outlet 34 is introduced into a disc stack centrifuge 36 via an inlet 38. The disk stack centrifuge 36 operates at high speed to further separate the liquid into an oily part discharged at an outlet 40, stick water discharged at an outlet 42 and a sludge discharged at an outlet 44.

[0061] FIG. 2 shows the first decanter centrifuge 20 according to the present invention. The decanter centrifuge 20 comprise a rotating bowl which defines a cylindrical bowl part 46 having the oily phase outlet 26 and a conical bowl part 48 having the slurry outlet 24.

[0062] A screw conveyor 50 is located inside the bowl between the oily phase outlet 26 and the slurry outlet 24. The screw conveyor 50 comprise apertures 52 for introduction of the heated item. A baffle 54 is optionally provided for preventing that the oily phase from flowing out though the slurry outlet 24. The baffle 54 defines a disk extending from the centre axis of the screw conveyor 50 outwardly towards the bowl. The item is fed into the decanter centrifuge 20 at the inlet 22. The screw conveyor defines a hollow axle 56 between the inlet 22 and the infeed 52. The axle 56 is rotated by a first motor 58 via a first gear whereas the bowl is rotated by a second motor 60. The decanter centrifuge 20 is held in a frame 62.

[0063] The rotation of the bowl causes the heavy material to accumulate at the bowl wall whereas the light material accumulated close to the axle 56. The screw conveyor 50 rotates at a different speed comparted to the bowl in order to force the solids collected on the walls of the bowl by the centrifugal force towards the slurry outlet. The cylindrical bowl part 46 is delimited by a large end hub 64 and the conical bowl part 48 is delimited by a small end hub 66. The oily phase outlet 26 at the large end hub 64 defines a liquid level defined between the oily phase which is light and due to the centrifugal force will accumulate close to the axle of the screw conveyor and the water phase which is heavier and accumulated closer to the bowl wall. The oily phase outlet 26 at the large end hub 64 and the slurry outlet 24 at the small end hub 66 are located about the same distance from the axle 56 in order to allow the slutty being a mixture of the water phase and the solids phase to be discharged at the same slurry outlet 24. The infeed 52 is preferably located closer to the large end hub 64 than the small end hub 66 in order to allow the item sufficient time moving inside the bowl to release as much oily phase as possible.

[0064] FIG. 3 shows a second decanter centrifuge 28 according to the present invention. The second decanter centrifuge 28 is similar to the first decanter centrifuge, however, it has a slightly different setup in order to optimize the separation of liquid and solids. The reference numerals used in connection with the second decanter centrifuge 28 provided with a (′) refers to the same part fulfilling the same function as the corresponding reference numeral in connection with the first decanter centrifuge 20. Hereinafter, only the differentiating feature will be discussed.

[0065] The liquid outlet 34 is located more distant from the axle 66′ compared to the first decanter 20, allowing the conical part of the bowl 48′ to define a dry beach area which allows the solids to dry off before being discharged through the solid outlet 32. Further, the inlet 52′ is located substantially in the middle between the large end hub 64 and the small end hub 66 in order to prevent any solids from being discharged at the liquid outlet 34.

EXAMPLE

[0066] A proof-of-concept experiment has been conducted by the applicant using the above setup. The starting product has the following composition: 40% oil, 15% solids and 45% water. The steam heater added 16% water in the form of steam.

[0067] The first decanter separated the heated item into an oily phase and a slurry phase: The oily phase has the following composition: 99% oil, 0% solids and 1% water. The slurry phase has the following composition: 2.6% oil, 19.3% solids and 78.1% water.

[0068] The second decanter separated the slurry into a solid product and an effluent phase: The solid product has the following composition: 2.3% oil, 42.7% solids and 55% water. The effluent phase has the following composition: 1.6% oil, 5.6% solids and 92.8% water.

[0069] The (optional) disc stack centrifuge separated the effluent into an oily part, sludge and stick water: The oily part has the following composition: 62% oil, 3.0% solids and 35% water. The sludge has the following composition: 2.4% oil, 12% solids and 85.6% water. The stick water has the following composition: 0.2% oil, 5.4% solids and 94.4% water.