Food or edible material: processes – compositions – and products – Fermentation processes – Of plant or plant derived material
Reexamination Certificate
2001-03-22
2003-07-08
Weier, Anthony J. (Department: 1761)
Food or edible material: processes, compositions, and products
Fermentation processes
Of plant or plant derived material
C426S597000, C426S442000
Reexamination Certificate
active
06589575
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for obtaining cold water infusible or extractable tea and to the products obtained thereby that have good colour and flavour.
BACKGROUND AND PRIOR ART
Leaf tea may be prepared as green leaf tea or black leaf tea. Generally, to prepare black leaf tea fresh green leaves of the plant
Camellia sinensis
are withered (subjected to mild drying), comminuted, fermented (in which process enzymes in the tea leaf use atmospheric oxygen to oxidise various substrates to produce brown-coloured products) and then fired (to dry the tea leaves). Green leaf tea is not exposed to the fermentation process. Partial fermentation may be used to produce intermediate-type teas known as “oolong” tea.
Tea is consumed as a hot beverage or a cold beverage such as iced tea. The numerous compounds in the leaves that give the beverage its unique organoleptical properties are only sparingly soluble in cold water so tea is usually infused in water at temperatures close to 100° C. When iced tea is desired the tea is infused in water at about 100° C. and then chilled in a refrigerator for example until it is cold. Unfortunately this can take several hours.
Once can prepare iced tea by dissolving the spray dried liquor obtained at high temperature from black tea or fibres generated during black tea manufacturing process in cold water.
U.S. Pat. No. 4,051,264 (Lipton/Sanderson) discloses a method for making a cold water soluble leaf tea extract. Tea leaves are pre-treated with tannase under anaerobic conditions to generate a cold-water infusing tea with good colour, yield and flavour.
U.S. Pat. No. 3,812,266 (Sanderson/Coggon) discloses a method that involves converting green tea to black using tannase and natural tea enzymes. The method also includes a tannase pre-treatment step, but in a slurry system, followed by oxidation by natural tea enzymes to convert green tea into black, and generate tea powders, which are both hot and cold water soluble.
The article by Tadao Kurata et al in Agr. Biol. Chem, 37 (6), 1471-1477, 1973 discloses that a red pigment is produced at the initial stage of the browning reaction of dehydro-L-ascorbic acid (DHA) with alpha-amino acid. 5-phenyl-3,4-diketo-gamma-butyrolactone, which has the same type of lactone ring structure as dehydro-L-ascorbic acid, is said to give a similar red colour when reacted with alpha-amino acid. The pigment is said to have the same structure as the red pigment that is produced by the oxidation of L-scorbamic acid.
Tannase is an expensive enzyme and is also not legally cleared in several countries for usage in tea. In any event, while this is convenient, for many consumers the quality of the final beverage is not equal to that prepared from hot infused leaves. Some consumers prefer not to use powders as they perceive them to be artificial, unnatural and simply lacking in the romance of taking tea.
There is therefore a need for a leaf tea that yields acceptable tea flavour and colour when infused in cold water.
The present inventors have now found that one can prepare a black leaf tea that provides a high quality tea beverage when infused in hot or cold water by treating tea leaves with one or more of ascorbic acid, dehydroascorbic acid, 1-scorbamic acid or 5-phenyl-3,4-diketo-gamma-butyrolactone (4-phenyl-2,3-diketo-gamma-butyrolactone) or their salts during black tea manufacture.
STATEMENT OF THE INVENTION
The present invention can be said in broad terms to relate to a process for manufacturing a cold water soluble black leaf tea comprising the steps of macerating freshly plucked tea leaves, allowing them to ferment, firing the leaves to arrest fermentation and then drying them to yield black leaf tea, the process being characterised in that the tea leaves are treated with a solubilising compound selected from the group consisting of ascorbic acid, dehydroascorbic acid, 1-scorbamic acid, 5-phenyl-3,4-diketo-gamma-butyrolactone or their salts and mixtures thereof in an amount that is sufficient for the black leaf tea to be soluble in water at 5 to 100° C.
The tea leaves are preferably treated with the solubilising compound in the presence of oxidative enzymes and/or hydrogen peroxide to enhance the tea flavour and colour.
“Tea” for the purposes of the present invention means leaf material from
Camellia sinensis
var.
sinensis
or
Camellia sinensis
var.
assamica.
It also includes rooibos tea obtained from
Aspalathus linearis
however that is a poor source of endogenous fermenting enzymes. “Tea” is also intended to include the product of blending two or more of any of these teas.
“Leaf tea” for the purposes of this invention means a tea product that contains one or more tea origins in an uninfused form.
“Cold water soluble” for the purposes of this invention means giving good colour, flavour and mouthfeel in a short infusion time i.e. less than 10 minutes, but preferably less than 5 minutes at a temperature at or above 5° C.
For the avoidance of doubt the word “comprising” is intended to mean including but not necessarily “consisting of” or “composed of”. In other words the listed steps or options need not be exhaustive.
DETAILED DESCRIPTION OF THE INVENTION
Tea manufacture, especially black tea manufacture, traditionally comprises: withering, macerating, fermenting and firing. Black tea for the purpose of the invention is obtained by the following process.
Withering is a process whereby the plucked tea leaves are stored for periods of time (perhaps up to 24 hours), during which they undergo various biochemical and physical changes which often includes a loss of moisture. It is optional but preferred.
Maceration follows the withering step, and traditionally the withered leaves are optionally rolled to bruise and crush the leaves i.e. break down the plant tissue structure. This will have the effect of liberating fermentable substrates and fermenting enzymes from within the plant cells and tissue. Modern tea manufacture usually includes this step however the plant cells and tissue is broken down by passing tea, which has usually been withered, through a cutting machine. Thus for the purpose of the invention the green tea leaves may be macerated using a CTC, ball mill or a grinder or a hammer mill or a LAWRI™ tea processor or a LEGG™ cutting machine or rolled using tea rollers as in orthodox tea processing.
The next step is commonly called fermentation but that is a misnomer. “Fermentation” is commonly used in the context of brewing alcohol to describe the action of exogenous enzymes. However in the tea world it is used to refer to the oxidative and hydrolytic process that tea undergoes when certain endogenous enzymes and substrates are brought together by mechanical disruption of the cells by macerating of the leaves. During this process colourless catechins in the leaves are converted to a complex mixture of yellow and orange to dark-brown substances and producing a large number of aromatic volatile compounds.
The fermented product is fired and dried to give a black leaf tea. The firing involves heating and drying the tea to destroy the fermenting enzymes and thereby arrest fermentation. It results in a reduction of moisture content to below 5%, and also leads to further chemical oxidation and changes in tea aroma. This generally involves exposing the tea to a blast of hot, dry air in a dryer.
The present invention concerns a modification to traditional black tea manufacture. The modification involves treating the tea leaves with a solubilising compound selected from the group consisting of ascorbic acid, dehydroascorbic acid, 1-scorbamic acid, 5-phenyl-3,4-diketo-gamma-butyrolactone or their salts and mixtures thereof in order to enhance the solubility of the black tea in cold water.
The solubilising compound 5-phenyl-3,4-diketo-gamma-butyrolactone referred to in the aforementioned article in Agr. Biol. Chem, 37 (6), 1471-1477, 1973 by Tadao Kurata et al has oxygen at the 1 position as is common when labelling heterocyclic compounds. However this compound can also be labelled as 4-phenyl-2,3-
Ganesan Velu
Ganguli Shovan
Garg Kush
Patel Mushtaq
Sinkar Vilas Pandurang
Lipton division of Conopco, Inc.
Weier Anthony J.
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