|Title of Invention||
AN IMPROVED METHOD OF OPTIMIZING THE PROCESS OF FERMENTATION IN BLACK TEA MANUFACTURE.
|Abstract||An improved fermentation method for manufacturing of black tea particularly the method for optimizing fermentation time en black tea manufacture comprising of the Infusion of fermenting leaves with boiling water at pH 6.02-8.0 for at least 3 min. followed by the treatment of filtrate with colour reagent (Bradford's reagent) to measure the developed colour at a suitable wavelength (585 nm) against the reagent blank solution. The procedure repeated at several time points during fermentation yields the optimum in fermentation time.|
|Full Text||FIELD OF INVENTION
The invention relates to an improved fermentation method for manufacturing of black tea particularly the method for optimizing fermentation time in black tea manufacture,
BACKGROUND OF INVENTION
Fermentation is a crucial step in the manufacture of black tea. The enzymatic and chemical oxidation of catechins, lipids and hydrolysis of flavanol glycosides are carried out during the process of fermentation. From the polyphenols or catechins, present to the extent of 30-32% of dry weight of fresh tea Feaves, theaflavins are produced by the endogenous enzymes of tea, viz. Polyphenol oxidase (PPO) and peroxidase (PO). Also, chemical oxidation takes part in the polymerization and condensation of theaflavins to thearubigins. To monitor these reactions, evaluation by nose is not adequate.
Hence, a fermentation test was designed at Tocklai in 1975 based on the chemical estimation of polyphenol (Ref.: K. L. Bajaj (1975) Tocklai Fermentation Test, Proceedings of the 27th Conference, Tocklai, PP 131-33). The test necessitates the addition of two reagents to the suitably diluted infusion of tea (Ref: S. Chakraborty (1976) Tocklai Fermentation Test, Two and a Bud 23:50-51 & M.N. Devchoudhury, et.al.(1992) Assessment of Fermentation of Tea, Two and a Bud 39: 38-41).
Tocklai fermentation test, developed at Tea Research Association, Tocklai, Jorhat, Assam was an objective method for the optimization of tea fermentation time. However, it involves different chemical solutions to be added in definite proportions sequentially and is time consuming. As the fermentation proceeds rapidly, during tea processing, the method of choice has to be fast and should require minimum number of additions. Hence, the present single step method of chemical quantitation of theaflavins is a superior than the method developed earlier. The present method involves addition of only one reagent directly to the infusion, so that time and manpower are saved and the test can be carried on the factory floor.
OBJECT OF INVENTION
The object of the invention is to substitute subjective method (by nose) of findina out the end point of tea fermentation which ieads to error by an objective method which is fast and accurate.
The further object of the invention is to develop a singe step method by single addition of chemical solution followed by measurement of optical density, which yields the result.
Another object of the invention is to develop a reproducible method, which correlates well with the classical method by nose.
STATEMENT OF THE INVENTION
An improved fermentation method for manufacturing of black tea particularly the method for optimizing fermentation time in black tea manufacture comprises of the following steps.
(i) Infusion of fermenting leaves with boiling water at pH 6.02-8.0 for at least 3 min.
(ii) Filtering the product obtained from step (i) and the filtrate is treated with colour reagent (Bradford's reagent) to measure the developed colour at a suitable wavelength (595 nm) against the reagent blank solution.
DESCRIPTION OF THE INVENTION WTH ACCOMPANYING DRAWING
Different embodiments of the invention are possible to achieve the best method of performance and to obtain the fermentation method for optimizing time in the manufacture of black tea. !t will be understood that skilled persons with many modifications, variations and adaptations may carry out the invention into practice without departing from its sprit or exceeding the scope of claims in describing the invention for the purpose of illustration.
Fig 1: Proportionality of Epigallocatechin gailate (EGCG) a major component of polyphenol with the colour developed by this method.
Fig 2: Proportionality of theaflavin with the colour developed by Bradford's reagent
Fig 3: Optimization of time of fermentation in tea manufacture by a time course reaction with fermenting tea leaves.
According to the invention, 3 gm fermenting leaves taken from different stages of fermentation (either on floor or conveyor belt of continuous fermentation machine) is infused with 150 ml boiling water at pH 7.0 for 3 minutes. It is filtered through glass funnel containing cotton wool or a strainer. 0.1 ml of the filtrate is diluted with 0.4 ml water and 4 ml 1:4 diluted Bradford's reagent (made by weighing out 0.1 g Coomassie brilliant blue G250, dissolving in 50 ml 95% ethanol and 100 ml orthophosphoric acid and diluted to 1 litre with water and filtered). The reagent can be stored indefinitely without dilution at 4°C.
The polyphenol dye conjugate develops blue colour within 2 min and is stable upto 1 hr. Absorption reading at 595 nm is taken in a Beckman Spectrophotometer or in a colorimeter with suitable red filter. A blank without polyphenol but only water and reagent is used to set 100% transmission in the instrument. The same reaction is to be carried out at definite time intervals during the process of fermentation and the absorbance values when plotted versus time in minutes give a maximum which corresponds to the optimum in fermentation time(fig 3)
To show the proportionality of catechins with the intensity of colour developed by Bradford reagent, purified epigallo-catechtn gailate (EGCG) is weighed (4 rng) and dissolved m 1 mi water. Different aliquots of this standard solution are used for calibration in the Bradford assay and lineanty of the curve is observed (fig. 1). it was
found that upto 100 ug. the cone Of FGCG is proportional to the absorbance at A595 but above that the reagent is not
Similarly, a linearity between theaflavin and the absorbance observed with Bradford's reagent is established. In this case a lower range of theaflavin is used and a linear relation is observed (fig. 2).
When the test is carried out in the fermentation floor of the Tocklai miniature factory after 30 min rolling and three CTC cuts, aliquots of fermenting mal (tea leaves) are taken at 10 min intervals. It is found that the absorption increased upto 70 min, starting from the time of rolling and then a dip in the color intensity with Bradford's reagent is observed (fig. 3). This peak indicated the optimum time of fermentation under the given conditions. Probably theaflavin synthesis is maximum in this case upto 70 min and then its conversion to thearubigin starts, which continues until fermented mal is dried. Hence, if one carries out the fermentation test at 10 min intervals, the process can be terminated at the correct stage. This is a more objective and reliable method than 'the nose', used by operators at tea factory routinely to determine the end point or fermentation.
This modified Tocklai fermentation test was compared with the earlier method by carrying out the tests simultaneously under factory condition. Identical results are obtained showing the equivalence of the methods.
The method was validated in about a dozen tea manufacturing factories for confirming the result.
1. An improved fermentation method for manufacturing of black tea particularly the method for optimizing fermentation time in black tea manufacture comprises of the following steps :
(i) Infusion of fermenting leaves with boiling water at pH 6.02-8.0 for at least 3 minutes
(ii) Filtering the product obtained from step (i) and the filtrate is treated with a reagent ( 100 mg Coomassic Brilliant Blue G250 dissolved in 50 ml 95% ethanol. 100 ml 85% ortho-phosphoric acid added and diluted to 1 litre with water. Filtered through Whatman No.1 filter paper). For 1 ml tea infusion 4 ml Bradford Reagent added.
(iii) The colour intensity is read in a colorimeter.
(iv) Carrying out the above steps at 10 min. time interval during the
fermentation step and obtaining the maximum in absorbance, which indicates the optimal time of fermentation.
2. The method as claimed in Claim 1 wherein the colour reagent is Bradford Reagent.
3. The method as claimed in claim 1 wherein the optimum wavelength is 595 nm.
4. The method as claimed in 1 wherein the pH is 7.0.
5. The method as claimed in the precccding claims substantially as herein described.
An improved fermentation method for manufacturing of black tea particularly the method for optimizing fermentation time en black tea manufacture comprising of the Infusion of fermenting leaves with boiling water at pH 6.02-8.0 for at least 3 min. followed by the treatment of filtrate with colour reagent (Bradford's reagent) to measure the developed colour at a suitable wavelength (585 nm) against the reagent blank solution. The procedure repeated at several time points during fermentation yields the optimum in fermentation time.
|Indian Patent Application Number||379/KOL/2004|
|PG Journal Number||17/2007|
|Date of Filing||01-Jul-2004|
|Name of Patentee||DR.PRANAB ROY.|
|Applicant Address||DEPT.BIOTECHNOLOGY UNIVERSITY OF BURDWAN ,GOLAPBAG|
|PCT International Classification Number||A 23 F 3/00|
|PCT International Application Number||N/A|
|PCT International Filing date|