WO2005103212A1

WO2005103212A1 - Method of and apparatus for use in the extraction of plant oil

Info

Publication number: WO2005103212A1
Application number: PCT/IB2004/001233
Authority: WO
Inventors: Nicolaas Daniel Lombard Burger; Adam Jacobus Von Wielligh; Rudolf Werner Ottermann
Original assignee: Nicolaas Daniel Lombard Burger; Adam Jacobus Von Wielligh; Rudolf Werner Ottermann
Priority date: 2004-04-23
Filing date: 2004-04-23
Publication date: 2005-11-03

Abstract

The invention provides a method and apparatus for extracting plant oil from material. The method involves comminuting plant material from wich the oil is to be extracted. The comminuted plant material is then mixed with a carrier medium, typically water. The mixture is subjected to a cell burst process to release the oil from the plant material. The plant oil is then separated from the mixture. The ground plant material is fed from the mill (12) to the holding tank (14)through the cell burst apparatus (16) to the holding tank (18) and then to the solid/liquid separator (22). The liquid (mixture of oil and water) dischargedfrom the separator (22) is fed to the third storage tank (24) and then to the separator (26) and if necessary to separator (28).

Description

METHOD OF AND APPARATUS FOR USE IN THE EXTRACTION OF PLANT OIL

THIS INVENTION relates to the extraction of plant oil. More particularly it relates to a method of and apparatus for use in the extraction of plant oil from plant material.

According to one aspect of the invention there is provided a method of extracting plant oil from plant material which method includes: comminuting plant material from which the oil is to be extracted; mixing the comminuted plant material with a carrier medium; subjecting the mixture to a cell burst process to release the oil from the plant material; and separating the plant oil from the mixture.

Comminuting the plant material may include grinding the material so that it has a maximum particle size of about 0.5mm. The plant material may be paprika.

In one embodiment of the invention, the complete fruit is ground. Preferably, the fruit is ground while it is still wet. In another embodiment of the invention, the pips may be removed from the fruit prior to grinding.

The carrier medium may be a liquid, particularly water. Typically, the comminuted plant material is mixed with water in a ratio of between 1 :1.5 and 1 :3 by volume to form a paste which is then subjected to the cell burst process. The method may include de-aerating and blanching the mixture before it is subjected to the cell burst process. The cell burst process may include subjecting the mixture to pressure variations which are sufficient to rupture the cell walls of the plant material.

More particularly the cell burst process may be the process described in South African Patent No. 87/7180 which is incorporated herein by reference.

The method may include diluting the mixture which has been subjected to the cell burst process. The method may include diluting the mixture with water in a ratio by volume of up to 1 :3 and preferably of about 1 :2.

The mixture may be maintained at a temperature of between 25 °C and 65 °C. Preferably the mixture is maintained at a temperature of between 40°C and 60°C.

The diluted mixture may be stirred continuously for a predetermined period of time, typically between 30 min and 60 min. The mixture which has been subjected to the cell burst process is diluted with clean water and heated to permit the oil to be washed out of the burst cells. The oil is in an emulsion after the cell burst process and when diluted it comes out of emulsion more easily. In addition, the mixture is too thick to flow easily and the dilution makes it more fluent. Further, the stirring assists in obtaining an even consistency and ensures that the oil emulsion mixes evenly with the water. After stirring, the mixture may be subjected to a first separation process in which the liquid and solid constituents are separated. Liquid and solid constituents may be separated using a centrifugal separation process.

The separated liquid, which comprises a mixture of oil and water, may be stored for a predetermined period of time typically 10 to 20 minutes. The liquid may be stored at a temperature of from 25°C to 60°C, preferably from 40 °C to 50 °C, and stirred continuously. The storing of the separated liquid permits oil micro-droplets to start separating from the water. In addition, it forms a buffer void to provide the content to be fed to the next step in the process described in more detail hereunder. The method may then include processing the separated liquid to separate the oil from the water. Separating the oil from the water may include a first separation stage in which the majority of the oil and water are separated and, if required, a second separation stage in which residual water is separated from the oil.

Separating the oil from the water may include cooling the liquid until the water freezes and separating the oil therefrom, using a centrifuge, absorbing water using a desiccant such as silica gel, aluminium oxide or magnesium sulphate, or a combination of these.

The method may include re-using the separated water to dilute the mixture after it has been subjected to the cell burst process. The re-use of the water enhances the yield of oil, as the water becomes saturated and thereafter operates only as a carrier of the oil. The invention extends to apparatus for carrying out the above method.

According to another aspect of the invention there is provided apparatus for use in extracting plant oil from plant material which apparatus includes a mixer whereby comminuted plant material can be mixed with a carrier medium; cell burst means for receiving the mixture from the mixer and rupturing the cells of the plant material to release the oil from the plant material; and separation means for separating the oil from the mixture.

The apparatus may include a holding tank, intermediate the cell burst means and the separation means, within which the product of the cell burst process can be contained, a heater for maintaining the contents of the holding tank at an elevated temperature and agitation means for agitating the contents of the holding tank. The separation means may include a solid/liquid separator and a liquid/liquid separator for separating the plant oil from the liquid received from the solid/liquid separator.

The apparatus may include a feed line for feeding the balance of the liquid, once the oil has been separated therefrom, to the holding tank to be mixed with the product of the cell burst process.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing which shows in block diagram form the apparatus for use in the extraction of plant oil from plant material. In the drawing, reference numeral 10 refers generally to apparatus for use in extracting plant oil from plant material. The apparatus 10 includes grinding means in the form of a mill 12.

The apparatus 10 includes a first holding tank 14 into which ground plant material from the mill 12 is fed and which in turn is connected to cell burst apparatus 16 such as that which is available from Natural Foods CC. If desired, intermediate the holding tank 14 and the cell burst apparatus 16 a de-aeration unit (not shown) may be provided. The cell burst apparatus 16 is connected to a second holding tank 18 which in turn is connected to separation means generally indicated by reference numeral 20.

The separation means 20 includes a solid/liquid separator 22. The solid/liquid separator 22 is typically a centrifugal separator that is able to separate liquids and solids due to high centrifugal forces. The separator

22 can be either a horizontal shaft (decanter) as supplied by GEA

Westvalia Company or by Alfa Laval. Instead, the separator 22 can be of the vertical shaft-type such as that which is available from GEA Westvalia or Alfa Laval. A liquid outlet of the separator 22 is connected to a third storage tank 24 which in turn is connected to a liquid/liquid separator 26.

The separator 26 may be of a centrifuge type such as that which is available from GEA Westvalia or Alfa Laval. If desired, the apparatus 10 may include a further separator 28 to which oil from the separator 26 is fed in order to remove any residual water therefrom as described in more detail here below. A feed line 30 extends from the separator 26 and, if supplied, the separator 28 to feed water discharged from the separators

26, 28 to the holding tank 18. In use, raw plant material, eg paprika, is fed into the mill 12 where it is ground to have a maximum particle size not greater than 0.5 mm but preferably smaller. The ground plant material is fed from the mill 12 to the holding tank 14 wherein it is mixed with water supplied from a water source through supply line 15. The plant material is mixed with water in a ratio of 1 part plant material to between 1.5 and 2 parts water by volume. A mixer is provided in the holding tank 14 to mix the water and ground plant material to form a paste. The paste is fed from the holding tank 14 through the cell burst apparatus 16 in which the cell walls of the plant material are ruptured in order to release the oil contained therein. If desired, prior to feeding the paste from the holding tank to the cell burst apparatus 16, it can be fed through a de-aeration and blanching unit in which it is subjected to a vacuum thereby to remove excess air and to soften the cell walls. The product of the cell burst apparatus 16 is fed into the holding tank 18 in which it is further diluted with water. A heater is provided in the holding tank 18 as well as agitation means, eg in the form of a stirrer, and the mixture is maintained at a temperature of the order of 40 °C to 50 °C and stirred continuously for a predetermined time period, typically of the order of 30 to 60 minutes. This allows proper extraction and dilution of the product. The mixture is then fed from the holding tank 18 to the solid/liquid separator 22. The solids are discharged and can, if desired, be sent for further processing, eg drying as illustrated by reference numeral 32 and grinding as illustrated by reference numeral 34. This material can be used as a spice in the food industry. Instead, if desired it can be mixed with fresh plant material for further processing. The liquid discharged from the separator 22 is fed to the third storage tank 24. This liquid comprises a mixture of oil and water and is maintained at the optimum temperature for separation, typically of the order of 40°C to 50°C and stirred continuously. Naturally this temperature may vary depending on the particular plant material being used. The liquid is then fed to the separator 26 in which the majority of the water phase is separated from the oil. If necessary, the oil from the separator 26 is fed to the separator 28 to remove any residual water which may still be mixed therewith. The oil is discharged along line 36 for further processing. Upon startup, fresh water is fed into the holding tank 18 to be mixed with the product from the cell burst apparatus 16. However, once the process is running, the water from the separators 26, 28 is fed to the holding tank 18 for mixing with the product from the cell burst apparatus 16. The Inventors have found that this results in a substantially higher yield of oil than is the case when fresh water is used.

Three sets of tests, namely A, B and C (see the table set out below) were conducted by the Inventor using paprika as the plant material. In each set of tests, three samples were subjected to the cell burst process at 28°C, 45°C and 60 ° C.

In Test A a dilution of cell burst paste to water in a ratio, by mass, of

1 part paste to two parts water was used. In Tests B and C, the dilution ratio was 1 :3. In both Tests A and B, fresh water was used to mix with the paste from the cell burst process. In Test C, recycled water was used, ie water extracted from the oil water mixture.

From the test results, it is clear that a substantial increase in the oil yield was achieved when the water was recirculated. Further, the increase in temperature also leads to an increase in yield.

The Inventors believe that the method and apparatus will also be suitable for extracting oil from other plant material such as ginger, coriander, grape seed and the like.

Claims

1. A method of extracting plant oil from plant material which method includes: comminuting plant material from which the oil is to be extracted; mixing the comminuted plant material with a carrier medium; subjecting the mixture to a cell burst process to release the oil from the plant material; and separating the plant oil from the mixture.

2. A method as claimed in claim 1 , in which comminuting the plant material includes aerating the material so that it has a maximum particle size of 0.5mm.

3. A method as claimed in claim 2, in which the plant material is paprika.

4. A method as claimed in claim 3, in which the complete fruit is ground.

5. A method as claimed in claim 3, in which the pips are removed from the fruit prior to grinding.

6. A method as claimed in any one of the preceding claims, in which the carrier medium is a liquid.

7. A method as claimed in claim 6, in which the carrier medium is water and the comminuted plant material is mixed with the water in a ratio between 1:1.5 and 1:3 by volume to form a paste which is then subjected to the cell burst process.

8. A method as claimed in any one of the preceding claims which includes blanching and de-aerating the mixture before it is subjected to the cell burst process.

9. A method as claimed in any one of the preceding claims, in which the cell burst process includes subjecting the mixture to pressure variations which are sufficient to rupture the cell walls of the plant material.

10. A method as claimed in any one of the preceding claims, which includes diluting the mixture which has been subjected to the cell burst process.

11. A method as claimed in claim 10, which includes diluting the mixture in a ratio of about 1 :2.

12. A method as claimed in claim 10 or claim 11 , in which the diluted mixture is maintained at a temperature of between 25°C and 65°C and is stirred continuously for a predetermined period of time.

13. A method as claimed in claim 12, in which the mixture is maintained at a temperature of between 40°C and 60°C.

14. A method as claimed in claim 12 or claim 13, in which the diluted mixture is stirred for between 30 minutes and 60 minutes.

15. A method as claimed in any one of claims 12 to 14, inclusive, in which, after stirring, the mixture is subjected to a first separation process in which liquid and solid constituents are separated.

16. A method as claimed in claim 15, in which the liquid and solid constituents are separated using a centrifugal separation process.

17. A method as claimed in claim 15 or claim 16, in which the separated liquid, which comprises a mixture of oil and water, is stored for a predetermined period of time.

18. A method as claimed in claim 17, in which the separated liquid is stored for between 10 to 20 minutes.

19. A method as claimed in claim 17 or claim 18, in which the liquid is stored at a temperature of from 25°C to 65°C.

20. A method as claimed in claim 19, in which the liquid is stored at a temperature of between 40°C and 60°C and is stirred continuously.

21. A method as claimed in any one of claims 17 to 20 inclusive, which includes processing the separated liquid to separate the oil from the water.

22. A method as claimed in claim 21 , in which separating the oil from the water includes a first separation stage in which the majority of the water is separated from the oil.

23. A method as claimed in claim 22, which includes a second separation stage in which residual water is separated from the oil.

24. A method as claimed in any one of claims 21 to 23, inclusive, which includes re-using the separated water to dilute the mixture after it has been subjected to the cell burst process.

25. Apparatus for carrying out the method claimed in any one of the preceding claims.

26. Apparatus for use in extracting plant oil from plant material which apparatus includes a mixer whereby comminuted plant material can be mixed with a carrier medium; cell burst means for receiving the mixture from the mixer and rupturing the cells of the plant material to release the oil from the plant material; and separation means for separating the oil from the mixture.

27. Apparatus as claimed in claim 26, which includes a holding tank, intermediate the cell burst means and the separation means, within which the product of the cell burst process can be contained, a heater for maintaining the contents of the holding tank at an elevated temperature and agitation means for agitating the contents of the holding tank.

28. Apparatus as claimed in claim 27, in which the separation means include a solid/liquid separator and a liquid/liquid separator for separating the plant oil from the liquid received from the liquid received from the solid/liquid separator.

29. Apparatus as claimed in claim 28, which includes a feed line for feeding the balance of the liquid, once the oil has been separated therefrom, to the holding tank to be mixed with the product of the cell burst process.