Cold water extractable tea leaf and process

• US 4,051,264 A
• Filed: 11/16/1976
• Issued: 09/27/1977
• Est. Priority Date: 09/05/1975
• Status: Expired due to Term

• Current Assignee: Conopco (Unilever PLC)
• Original Assignee: Thomas J Lipton Incorporated (Stichting Administratiekantoor Unilever N.V.)
• Inventors: Graham, Harold Nathaniel, Sanderson, Gary Warner, Coggon, Philip, Hoefler, Andrew Charles
• Primary Examiner(s): Weinstein, Steven L.
• Application Number:
  US05/742,281
• Time in Patent Office: 315 Days
• Field of Search: 426/52, 426/597, 426/49
• US Class Current: 426/52
• CPC Class Codes: A23F 3/10 Fermentation with addition of microorganisms or enzymes
• CPC Class Codes: A23F 3/166 Addition of, or treatment with, enzymes or microorganisms

Abstract

Cold water extractable tea leaf is prepared by treatment of fresh green tea with the enzyme tannase under anaerobic conditions. The cold water extractable tea leaf is also used to prepare an instant tea product.

Claims

1. A process for preparing black tea leaf from green tea leaf which comprises the steps of comminuting freshly harvested green tea leaf, treating the comminuted fresh green tea leaf with tannase at a temperature and for a time sufficient to impart a substantial cold water extractability to the manufactured tea leaf, fermenting the treated green tea leaf, and firing the fermented tea leaf to reduce the moisture content of the tea leaf to below about 5% and produce a cold water extractable fired black tea leaf.

2. In a process for preparing manufactured green tea leaf, the improvement comprising the steps of bringing comminuted green tea leaf into contact with tannase under essentially anaerobic conditions at a temperature and for a time sufficient to impart a substantial cold water extractability to the manufactured tea leaf, and thereafter firing the tea leaf to reduce the moisture content of the tea leaf to below about 5%.

3. A process for preparing manufactured green tea leaf which comprises the steps of heating freshly harvested green tea leaf at a temperature and for a time sufficient to inactivate tea leaf enzymes before fermentation has taken place, comminuting the tea leaf, treating the comminuted tea leaf with tannase at a temperature and for a time sufficient to impart a substantial cold water extractability to the manufactured tea leaf, and firing the treated tea leaf to reduce the moisture content of the tea leaf to below about 5%.

4. A process for preparing black tea leaf from freshly harvested green tea leaf comprising the steps of preparing fresh green tea leaf for fermentation by comminution techniques, adding tannase to the comminuted tea leaf at a level of from about 2 to about 20 units per gram of tea leaf, while maintaining the temperature of the tea leaf within the range of about 25°

C to about 45°

C and maintaining essentially anaerobic conditions, maintaining the tea leaf in contact with tannase to provide a substantial increase in cold water extractable solids, fermenting the tannase contacted tea leaf under aerobic conditions, and firing the fermented tea leaf to reduce the moisture content of the tea leaf to below about 5% and produce a cold water extractable fired black tea leaf.

5. The process of claim 4, wherein said anaerobic conditions are maintained up to 30 minutes.

6. The process of claim 4, wherein the tannase is added at a level of 8 enzyme units per gram of dry green tea leaf.

7. The process of claim 4, wherein potassium hydroxide is added to the comminuted green tea leaf prior to the step of tannase treatment to provide a pH within the range of about 4.5 to 7.5.

8. The process of claim 4, wherein sufficient alkali is added after the tannase treatment to adjust the pH to that of the original comminuted tea leaf.

9. A process for preparing black tea leaf from freshly harvested green tea leaf which comprises the steps of commimuting freshly harvested green tea leaf, adding the comminuted tea leaf to water to form a tea slurry, treating the tea slurry with tannase under essentially anaerobic conditions at a temperature and for a time sufficient to impart a substantial cold water extractability to the manufactured tea leaf, fermenting the treated tea slurry, and drying the fermented tea slurry with a firing step at the terminus of the drying process, to reduce the moisture content of the tea leaf to below about 5% and to provide a cold water extractable fired black tea leaf.

10. A process for preparing black tea leaf from freshly harvested green tea leaf which comprises the steps of comminuting freshly harvested green tea leaf, adding the comminuted tea leaf to water to form a tea leaf slurry, maintaining the tea leaf slurry at a temperature from 25°

C to 50°

C for a time sufficient to provide a substantial amount of extracted tea solids, separating the tea leaf slurry into extract and tea leaf residue, treating the extract with tannase immobilized on a solid support, adding the extracted tea leaf residue back to the tannase-treated extract to form a second tea leaf slurry, fermenting the second tea leaf slurry, and drying the fermented second tea leaf slurry with a firing step at the terminus of the drying process, to reduce the moisture content of the tea leaf to below about 5% and to provide a cold water extractable fired back tea leaf.

11. A process for preparing an instant tea which comprises the steps of comminuting freshly harvested green tea leaf, treating the comminuted green tea leaf with tannase at a temperature and for a time sufficient to impart a substantial cold water extractability to the tea leaf, fermenting the treated green tea leaf, firing the fermented tea leaf to reduce the moisture content of the tea leaf to below about 5%, preparing a hot water extract of the tea leaf, polishing the tea extract, and drying the extract to provide a powdered instant tea.

12. A process for preparing an instant tea which comprises the steps of comminuting freshly harvested green tea leaf, adding tannase to the comminuted green tea leaf at a level of from about 2 to about 20 units per gram of the greem tea leaf, maintaining the tea leaf in contact with the tannase at a temperature within the range of about 25°

C to about 45°

C under essentially anaerobic conditions for a sufficient time to provide a substantial increase in extractable solids, fermenting the tannase contacted tea leaf under aerobic conditions, firing the fermented tea leaf to reduce the moisture content of the tea leaf to below about 5%, preparing a hot water extract of the fired tea leaf, polishing the tea extract and drying the extract to provide a powdered instant tea.

13. In a process for preparing black tea leaf from comminuted fresh green tea leaf, the improvement comprising the steps of contacting the comminuted green tea leaf with tannase at a temperature and for a time sufficient to provide a substantial increase in cold water extractable solids, fermenting the tannase contacted tea leaf and firing the fermented tea leaf to reduce the moisture content of the tea leaf of below about 5% and produce a cold water extractable fired back tea leaf.

14. A cold water extractable fired black tea leaf prepared by comminuting freshly harvested green tea leaf, treating the comminuted fresh green tea leaf with tannase at a temperature and for a time sufficient to impart a substantial cold water extractability to the manufactured tea leaf, fermenting the treated green tea leaf and firing the fermented tea leaf to reduce the moisture content of the tea leaf to below about 5% and produce a cold water extractable fired black tea leaf.

15. A cold water extractable fired green tea leaf prepared by heating freshly harvested green tea leaf at a temperature and for a time sufficient to inactivate tea leaf enzymes before fermentation has taken place, comminuting the green tea leaf, treating the comminuted tea leaf with tannase at a temperature and for a time sufficient to impart a substantial cold water extractability to the manufactured tea leaf, and firing the treated tea leaf to reduce the moisture content of the tea leaf to below about 5% and to produce a cold water extractable fired green tea leaf.

16. A process for preparing oolong tea leaf from green tea leaf which comprises the steps of comminuting freshly harvested green tea leaf, treating the comminuted fresh green tea leaf with tannase at a temperature and for a time sufficient to impart substantial cold water extractability to the manufactured tea leaf, fermenting the treated green tea leaf for a time sufficient to impart oolong character, and firing the fermented tea leaf to reduce the moisture content of the tea leaf to below about 5% and produce a cold water extractable fired oolong tea leaf.