Decaffeination methods and systems

• US 10,426,178 B2
• Filed: 03/17/2015
• Issued: 10/01/2019
• Est. Priority Date: 03/26/2014
• Status: Active Grant

• Current Assignee: Infré SA
• Original Assignee: Infré SA
• Inventors: Fischer, Norbert, Weber, Carlo
• Primary Examiner(s): Heggestad, Helen F
• Application Number:
  US15/128,991
• Publication Number:
  US 20170202234A1
• Time in Patent Office: 1,659 Days
• Field of Search: 426427, 426431, 426434, 426435
• CPC Class Codes: A23F 3/36 Reducing or removing alkaloid content; Preparations produced thereby; Extracts or infusions thereof
• CPC Class Codes: A23F 3/385 using flocculating, precipitating, adsorbing or complex-forming agents, or ion-exchangers

Abstract

Disclosed is a water based method for extracting caffeine from alkaloid containing substances, in particular tea leaves. The method can be performed without the use of artificial substances. The method allows the other soluble, non-caffeine components of alkaloid containing substances to be part of the decaffeinated product, in particular, components such as catechins and antioxidants. Advantageously, the caffeine extracted from the alkaloid containing substances is reversibly adsorbed to an adsorbent and high percentile of the caffeine can be recovered from the adsorbent.

Claims

1. A water based method for producing decaffeinated tea leaves comprising:

(i) adding water having a temperature of less than 70°

C. (degrees Celsius) to tea leaves to form an aqueous tea leaf mixture;

(ii) separating the tea leaves from the aqueous tea leaf mixture to obtain an aqueous extract and extracted tea leaves;

(iii) contacting the aqueous extract of (ii) with an active carbon adsorbent (ACA);

(iv) adsorbing caffeine in the extract reversibly to the ACA to obtain an aqueous decaffeinated tea extract (DTE);

(v) contacting the aqueous DTE of (iv) with the extracted tea leaves of (ii) to form a further aqueous tea leaf mixture, repeating (ii) to (v) until at least 85% of the caffeine is removed from the tea leaves, wherein

(i) to (v) are water-based, and

the repeating of (ii) to (v) causes an increase in concentration, up to the equilibrium concentration, of non-caffeine water soluble tea components in the aqueous DTE, which causes a reduction of the extraction of non-caffeine water soluble tea components from the tea leaf into the aqueous DTE in the repeated steps, and

(vi) drying the further aqueous tea leaf mixture to obtain the decaffeinated tea leaves, wherein the decaffeinated tea leaves retain at least about 50% of the non-caffeine water soluble components of the tea leaves provided in (i).

2. The method of claim 1, wherein (ii) to (v) is repeated 2 to 12 times.

3. The method of claim 1, wherein the time between adding the water or DTE to form the aqueous tea leaf mixture in (i) or the further aqueous tea leaf mixture in (v) and separating the extracted tea leaves in (ii) is more than 2 minutes, but less than 60 minutes.

4. The method of claim 1 further comprising adding a solvent to the ACA and desorbing the caffeine adsorbed thereto, and optionally reusing the ACA in contacting a further aqueous extract of (ii) with the ACA.

5. The method of claim 4, wherein the caffeine desorbed is recovered from the solvent and the solvent is optionally recirculated to the ACA.

6. The method of claim 5, wherein the caffeine is dried by evaporating the solvent.

7. The method of claim 4, wherein the solvent is an alcohol or an ester.

8. The method of claim 4, wherein more than 60%, 70%, 80%, 90%, 95% or 98% of the caffeine adsorbed is resorbed from the ACA and is dissolved in the solvent.

9. The method of claim 1, wherein the ACA is part of an adsorption column.

10. The method of claim 1, wherein the ACA comprises porous carbon particles, wherein more than 90% of the particles have a size range of 0.1 to 0.66 mm and a surface area of higher than 1300 m²/g.

11. The method of claim 10, wherein the ACA has an iodine number that is higher than 1350 mg/g.

12. The method of claim 1, wherein the ratio of the tea leaves to water in (i) is 1:

5 to 1;

10.

13. The method of claim 1, wherein the water or aqueous tea leaf mixture in (i) or the DTE of (v) is less than 60°

C. when mixed with the tea leaves or extracted tea leaves.

14. The method of claim 1, wherein the separating in (ii) is centrifugal separating at a g-force in the range of 2-100 m/s².

15. The method of claim 14, wherein the centrifugal separating is performed in a continuous flow centrifuge or a solid-bowl centrifuge.

16. The method of claim 1, wherein the tea leaves comprise black tea or green tea (Camellia sinensis L.), or Mate tea (Ilex paraguariensis L.).

17. The method of claim 1, wherein at least 85%, 90% or 95% of the caffeine is removed from the tea leaves.

18. The method of claim 1, wherein the tea leaves in (vi) comprise at least about 60%, 70%, 80% of the non-caffeine water soluble components of the tea leaves provided in (i).

19. The method of claim 1, wherein the non-caffeine water soluble components are tea polyphenols, amino acids, theaflavin or derivatives thereof, and/or thearubigine.

20. Decaffeinated tea leaves according to claim 1 comprising less than 0.3% of caffeine and at least 40%/a, 50%, 60%, 70%, 80% or 90% of tea catechins, tharubigine and/or polyphenols of the tea leaves they are made from.

21. The method of claim 2, wherein (ii) to (v) is repeated 4 to 10 times.

22. The method of claim 3, wherein the time between adding the water or DTE to form the aqueous tea leaf mixture in (i) or the further aqueous tea leaf mixture in (v) and separating the extracted tea leaves in (ii) is between 2 and 20 minutes.

23. The method of claim 7, wherein the alcohol is methanol or ethanol, or the ester is ethyl acetate.

24. The method of claim 10, wherein the carbon particles are round.

25. The method of claim 22, wherein the water or aqueous tea leaf mixture in (i) or the DTE of (v) is 5°

C. to 60°

C. when mixed with the tea leaves or extracted tea leaves.

26. The method of claim 15, wherein the continuous flow centrifuge or the solid-bowl centrifuge are a countercurrent centrifuge or a concurrent centrifuge.

27. The method of claim 1, wherein the caffeine remaining in the decaffeinated tea leaves does not exceed 0.3%, 0.2% or 0.1%.

28. The method of claim 1, wherein the decaffeinated tea leaves in (vi) comprise:

at least about 90% of the non-caffeine water soluble components of the tea leaves provided in (i).

29. The method of claim 19, wherein the tea polyphenols include up to 30% of catechins and/or epicatechins of a dry weight of the tea leaves, L-theanin, and theaflavin-3-gallate.

30. The method of claim 1, wherein the decaffeinated tea leaves comprise less than 0.3% of caffeine and at least 40%, 50%, 60%, 70%, 80% or 90% of tea catechins, tharubigine and/or polyphenols of the tea leaves they are made from.

31. The method of claim 30, wherein the tea catechins are theaflavins, and the polyphenols are epicatechins.

32. The method of claim 25, wherein the water or aqueous tea leaf mixture in (i) or the DTE of (v) is 15°

C. to 50°

C. when mixed with the tea leaves or extracted tea leaves.

33. The method of claim 32, wherein the water or aqueous tea leaf mixture in (i) or the DTE of (v) is 15°

C. to 30°

C.

34. The method of claim 1, wherein (i) and (ii) are performed in a centrifuge.

35. The method of claim 1, wherein the caffeine remaining in the decaffeinated tea leaves does not exceed 0.4%.