WO2015082191A1

WO2015082191A1 - A process for producing a tea product

Info

Publication number: WO2015082191A1
Application number: PCT/EP2014/074567
Authority: WO
Inventors: Reshmee Mukhopadhyay; Sreejit Achuthan NAIR; Gurmeet Singh; Mohamed Sirajudeen JAHABARDEEN; Purna Venkatesh
Original assignee: Unilever N.V.; Unilever Plc; Conopco, Inc., D/B/A Unilever
Priority date: 2013-12-06
Filing date: 2014-11-14
Publication date: 2015-06-11
Also published as: AR098607A1

Abstract

The present invention relates to a process for producing a leaf tea product comprising the step of treating fresh tea leaf with a polyphenol extraction enhancement agent selected from alkoxylated non-ionic surfactant at a concentration above the Critical Micelle Concentration (CMC), saturated hydrocarbon, enzyme with cutinase activity of at least 5 KU/g, and combinations thereof.

Description

A PROCESS FOR PRODUCING A TEA PRODUCT Field of the invention

The present invention relates to a process for producing a tea product, and more particularly to a process for producing a leaf tea product.

Background of the invention

Tea is one of the most extensively consumed beverages in the world. There are different varieties of tea e.g. black tea, green tea, oolong tea, white tea, etc. Among different varieties, black tea products are more popular. These varieties of teas are available in different formats. Leaf tea products are one of the most popular formats. Leaf tea products may be brewed and consumed in different ways. To obtain a hot tea beverage the leaf tea product may directly be brewed in hot water or a tea bag containing the leaf tea product may be put in hot water for brewing.

Polyphenols are considered to be the major constituents in most of the tea product. It is believed that the polyphenols provide the required taste (astringency, bitterness etc.) for a tea product and also provide various health benefits. Polyphenols are known to be one of the "tea goodies". We have found that in whatever way a leaf tea product is brewed, the leaf tea waste produced after brewing the beverage contains a good amount of polyphenols which remain unused and go as waste after the brewing process. As a result the brewed tea ends up with less polyphenols than it could potentially contain.

Different treatments of tea leaf are known. Also there have been efforts to increase the polyphenols content in a tea product.

WO 2012/133901 (KANNO MINORU et.al., 2012) describes a polyphenol increasing agent for plant leaves that enables an increase in the storage life of plant leaves such as leaf vegetables and tea leaves, a polyphenol and amino acid increasing agent for plant leaves, a resin pellet, a plant leaf storage sheet, and a method for manufacturing a plant leaf storage sheet. WO 2009/014758 (WELL-GEN, INC., 2009) provides various products and processes such as a process of making a theaflavins enriched extract of tea having a low content of high molecular weight thearubigins which comprises extracting theaflavins from tea using ethanol to produce an extract having a high theaflavins content and a low content of high molecular weight thearubigins.

WO 2006/1 1 1 163 (NOVOZYMES A S, 2006) discloses method for producing a plant extract comprises incubating a plant material with an enzyme composition comprising a lipolytic enzyme. Although the prior art discloses treatment of tea leaf to obtain a tea product with higher polyphenols content, it is silent about how to increase the extractability of the polyphenols from the leaf matrix to utilize the polyphenols that are already there in the leaf and which are otherwise discarded with the used tea leaves as waste after brewing the beverage.

Therefore there is a need to provide a process which permits higher extractability of the polyphenols from the leaf-matrix thereby reduce the wastage of polyphenols and also provides an end cup tea beverage with a higher amount of polyphenols.

Objects of the invention

It is therefore an object of the present invention to provide a process for producing a leaf tea product. It is another object of the present invention to provide a process which improves the extractability of the polyphenols from the tea leaf.

It is a further object of the present invention to provide a black leaf tea product with relatively higher polyphenols delivery at the end cup to minimize the wastage of polyphenols.

The present inventors while working extensively to solve this problem have surprisingly found that a treating the leaf with a polyphenol extraction enhancement agent selected from a particular group produces a tea product which is superior in terms of polyphenols delivery at the end cup and thereby satisfies one or more of the above said objects.

Summary of the invention

In a first aspect the present invention provides a process for producing a leaf tea product comprising the step of treating fresh tea leaf with a polyphenol extraction enhancement agent selected from alkoxylated non-ionic surfactant at a concentration above the Critical Micelle Concentration (CMC), saturated hydrocarbon, enzyme with cutinase activity of at least 5 KU/g, and combinations thereof.

Any feature of one aspect of the present invention may be utilized in any other aspect of the invention. 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. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about". Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated.

Detailed description of the invention

"Tea" for the purposes of the present invention means material from Camellia sinensis var. sinensis and/or Camellia sinensis var. assamica. Especially preferred is material from var. assamica as this has a higher level of tea actives than var. sinensis.

"Leaf tea" for the purposes of this invention means a tea product that contains tea leaves and/or stem in an uninfused form, and that has been dried to a moisture content of less than 30% by weight, and usually has a water content in the range 1 to 10% by weight (i.e. "made tea").

"Fresh tea leaf refers to tea leaf, buds and/or stem that have never been dried to a water content of less than 30% by weight, and usually have water content in the range 60 to 90%. "Black tea" refers to substantially fermented tea. Black tea has different characteristics than green tea. Black tea is more astringent in taste and less bitter than green tea. The redness of the black tea liquor is also significantly higher than green tea. Black tea also contains higher levels of theaflavins. "Fermentation" refers to the oxidative and hydrolytic process that tea undergoes when certain endogenous enzymes and substrates are brought together, e.g., by mechanical disruption of the cells by maceration of the leaves. During this process colourless catechins in the leaves are converted to a complex mixture of yellow and orange to dark-brown polyphenolic substances. The present invention provides a process for producing a leaf tea product comprising the step of treating fresh tea leaf with a polyphenol extraction enhancement agent selected from alkoxylated non-ionic surfactant at a concentration above the Critical Micelle Concentration (CMC), saturated hydrocarbon, enzyme with cutinase activity of at least 5 KU/g, and combinations thereof.

Polyphenols are the major constituents in tea leaf and believed to be beneficial for health. The term "polyphenol extraction enhancement agent" refers to any agent/material that is able to extract significant amount of polyphenols from the tea leaf matrix thereby produce an end cup tea beverage with relatively higher polyphenols content and reduce the wastage of this important constituent of tea.

According to the process of the present invention, the polyphenol extraction enhancement agent is selected from alkoxylated non-ionic surfactant at a concentration above the Critical Micelle Concentration (CMC), saturated hydrocarbon, enzyme with cutinase activity of at least 5 KU/g, and combinations thereof. Surfactants are surface active agents. They are generally amphiphilic in nature i.e. they have both hydrophobic (water hating) groups and hydrophilic (water loving) groups in their structures. Most common surfactants are classified according to their polar head group. A non-ionic surfactant carries no charge group in this head, whilst the head of an ionic surfactant carries a net charge. Surfactants are widely used in both food and personal/home care products. In food products they are mostly used to stabilize emulsions and/or suspensions.

The surfactants used in the process of the present invention are non-ionic. More particularly, the non-ionic surfactants is alkoxylated, which means they have an alkoxy group (-OR, where R is an alkyl group) as their head group. The most preferred surfactants are polysorbates.

The amount of surfactant added in the above process is preferably in the range of 0.01 - 5%, more preferably 0.1 to 5% and further more preferably 1 to 5% by dry weight of tea leaf. The surfactant is added at a concentration above the Critical Micelle Concentration (CMC) of the surfactants. In colloid chemistry the CMC is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system it goes to micelles.

The present invention also uses saturated hydrocarbons as one of the polyphenol extraction enhancement agent in the process. Hydrocarbons are organic molecules consisting of only hydrogen and carbon as their elemental constituents. Hydrocarbons are naturally occurring in crude oil. Both saturated and unsaturated hydrocarbons are available. Saturated hydrocarbons are the simplest form of hydrocarbon which are composed entirely of single bonds and are saturated with hydrogen.

The preferred hydrocarbons for the purpose of the present inventions are selected such that the number of carbon atoms in the saturated hydrocarbon is 5 to 10 and more preferably 6 to 10.

One of the polyphenol extraction enhancement agents used in the process of the present invention is an enzyme with cutinase activity of at least 5 KU/g [KU= kilo unit]. The preferable activity of the enzyme is at least 6 KU/g, more preferably at least 7 KU/g and further more preferably at least 8 KU/g, and most preferably at least 10 KU/g. One unit (U) of cutinase activity is defined as the amount of enzyme required to convert Ι μιτιοΙ of p-nitrophenyl butyrate to p-nitrophenol (p- NP) in one minute. The amount of enzyme added in the treatment preferably in the range of 0.02 - 4%, more preferably 0.2 to 4% and most preferably 1 to 4% by dry weight of tea leaf. Optionally in the process, after plucking there is a step of withering of the fresh tea leaf before said treatment. The tea leaf may include leaf, buds, stem and other parts of the tea plant. Withering is a process where plucked tea leaf are allowed to lose moisture over a period of time preferably in a shallow trough where biochemical reactions occur causing formation of many beneficial compounds including aroma compounds. Preferably to speed-up the moisture loosing process fresh dry air is passed in a regulated manner through the leaf. Withering is generally carried out for a period of 10 to 18 hours, more preferably for 12 to 16 hours. Preferably after the treatment with a polyphenol extraction enhancement agent the tea leaf undergoes maceration when the polyphenol extraction enhancement agent is selected from alkoxylated non-ionic surfactant or saturated hydrocarbon or combinations thereof. Maceration is a process where the tea cellular structure is broken which causes further biochemical reaction to occur. This can be done in different ways. Preferably it is done either by CTC or by the orthodox method. The main aim of this process is to damage the leaf to break the cellular structure. In the CTC process it is done by CTC machine where three actions viz. cutting, tearing and curling are performed on the tea leaf. In the orthodox process it is done by subjecting the tea leaf to a rolling movement under pressure and then twisting the leaf thereby rupturing the cells and releasing the juice.

When the polyphenol extraction enhancement agent is enzyme then the tea leaf optionally undergoes maceration before or after the said treatment. Optionally (and preferably after maceration) the tea leaf undergoes fermentation. Fermentation is a process in which enzymes in the tea leaf use atmospheric oxygen to oxidize various substrates to produce coloured products. This step may be preferably achieved by exposing the macerated tea leaf in open atmosphere (~25°C) in presence of oxygen for 15 minutes to 4 hours.

Preferably the fermented leaf is then subjected to drying. The tea leaf is dried to a moisture content of less than 10% preferably moisture content of less than 5% by dry mass of the tea leaf. Drying is the process where the tea leaf is contacted with air at a temperature of preferably 50-100°C, during which the leaf losses moisture and the enzyme activities are stopped. By drying, the moisture content of the tea leaf is brought down to less than 10% preferably 2-3%. Tray drier or fluidized bed drier may preferably be used for drying the tea leaf. In an alternate embodiment, after the treatment with polyphenol extraction enhancement agent there is a step of deactivation of endogenous tea enzymes to arrest fermentation of the tea leaf. This can be preferably achieved by heat treatment of the tea leaf such as pan firing. The invention will now be demonstrated by way of examples. These examples are for illustration only and in no way limit the scope of the invention.

Examples

Measurement of polyphenols in tea infusion:

Tea infusion was prepared by taking leaf tea product (2g) in a cup followed by adding 100 ml_ of boiling water and stirring for 2 minutes. The used tea leaves were then separated by filtration to obtain the tea infusion.

Tea infusions for different samples were made using the same protocol as mentioned above. After obtaining the tea infusions the polyphenols content was measured by using the ISO method for the determination of content of total polyphenols in tea - Colorimetric method using Folin-Cicalteu reagent; ISO 14502-1 :2005(E). Process of treatment of the fresh tea leaf with polyphenol extraction enhancement agent:

a) Treatment with Surfactant:

Fresh tea leaves were procured from South Indian tea garden and were soaked in the following solutions of Tween 20 (CMC = 0.007 wt %):

Example A:

1 kg tea leaf was soaked in 1 L of 0.004 wt % Tween 20 solution (below CMC). Example 1 :

1 kg tea leaf was soaked in 1 L of 0.1 wt % Tween 20 solution.

Example 2:

1 kg tea leaf was soaked in 1 L of 1 wt % Tween 20 solution.

After 2 hours the treated leaves were drained to separate out the leaves. The treated leaves were then spread out in an open area for withering for 16 hours at a temperature of ~25°C. After that the leaves were macerated through a Cut, Tear and Curl (CTC) process. Then the macerated leaves were kept for 90 minutes fermentation. After fermentation stage, the leaves were dried using a Fluidized Bed Dryer at 1 10°C. The dried black tea sample was subjected to fibre removal through a Fibre Extractor. The samples were graded as per standard procedure based on size. The leaf fraction collected on ASTM mesh number 18 and 20 were combined together. Infusions were prepared from the samples followed by polyphenols analysis using the procedure as described in this specification. As a control experiment, one set of leaves were processed in the same manner as described above which was not undergone any surfactant treatment (Example B). The results are summarized in the following Table 1 .

Table 1 :

From the above table it is evident that examples which are inside the scope of the present invention (Example 1 and 2) are provides a tea product where the extractability of the polyphenol is much higher than examples that are outside the scope of the present invention (Examples A and B). Therefore it is clear that present invention provides a tea product where higher amount of polyphenols get extracted and comes out in the infusion and reduce the wastage of polyphenols. It is also evident from the above table that surfactant used below its CMC level (Example A) is not effective to increase the extractability of polyphenols. b) Treatment with hydrocarbon (Example 3):

Fresh tea leaves (initial moisture content of 77 %) from South Indian gardens were withered for 16 hours (at ~ 25°C). After withering, about 1 kg of tea leaves were soaked in 1 L of Hexane (procedure from Sigma) and incubated for 2 hours at ambient temperature. After 2 hours the hexane treated leaf was drained to separate the leaf. The treated leaves were spread out in an open area for 1 hour under constant air flow to further remove residual hexane. The hexane treated leaf was taken for maceration through a Cut, Tear and Curl (CTC) process. Then the macerated leaf was kept for 90 minutes fermentation. After fermentation stage the leaf was dried using a Fluidized Bed Dryer at 1 10°C. The dried black tea sample was subjected to fibre removal through a Fibre Extractor. Th e samples were graded as per standard procedure based on size. The leaf fraction collected on ASTM mesh number 18 and 20 were combined together. Infusions were prepared from the samples followed by polyphenols analysis using the procedure as described in this specification.

As a control of this experiment one sample was taken where there was no treatment with Hexane (Example C).

The results are summarized in the following Table 2.

Table 2:

From the above table it is evident that examples that are inside the scope of the present invention (Example 3) are provides a tea product where the extractability of the polyphenol is much higher than control example (Example C). c) Treatment with Enzyme:

For this purpose the enzyme with cutinase activity was obtained from Novozymes (Novozym® 51032, Cutinase activity: 15 KU/g).

Example D:

This is a control example for which no treatment with enzyme was done. The fresh tea leaf was processed in the same manner to produce black leaf tea as explained below except any treatment. Example 4:

After receiving the fresh tea leaves from South Indian gardens, about 1 kg of fresh leaves were soaked in 1 L of Cutinase (0.1 wt%) solution for 2 hours. Then the treated leaves were left for 16 hours for withering (at ~25°C) to obtain leaf with moisture content of about 70%. After withering, treated leaves were taken for maceration in Cut, Tear and Curl (CTC) process. Then the macerated leaves were kept for 90 minutes fermentation. After fermentation stage the leaves were dried using a Fluidized Bed Dryer at 1 10°C. The dried black tea sample was subjected to fibre removal through a Fibre Extractor. The samples were graded as per standard procedure based on size. The leaf fraction collected on ASTM mesh number 14 and 16 were combined together. Infusions were prepared from the samples followed by polyphenols analysis using the procedure as described in this specification.

Example 5:

In another batch, after receiving the fresh tea leaves from South Indian gardens, 1 kg of the leaves were left for 16 hours for withering (at ~25°C) to obtain leaves with moisture content of about 70%. After withering, leaves were macerated in CTC process and then the cutinase of about 0.5 wt% based on dry tea were added on the macerated leaf and it was left for about 90 minutes fermentation. After fermentation stage the leaf was dried using a Fluidized Bed Dryer at 1 10°C. The dried black tea sample was subjected to fibre removal through a Fibre Extractor. The samples were graded as per standard procedure based on size. The leaf fraction collected on ASTM mesh number 14 and 16 were combined together. Infusions were prepared from the samples followed by polyphenols analysis using the procedure as described in this specification. The results are summarized in the following Table 3. -14-

Table 3:

From the above table it is clear that Examples 4 and 5 (with enzyme treatment according to the present invention) produces a tea wherein the extractability of polyphenols are significantly higher than control Example D.

It is therefore very evident from the above description that by way of present invention it is now possible to provide a black tea product which improves the extractability of the polyphenols from the tea leaf and with relatively higher polyphenols delivery at the end cup for minimizing the wastage of polyphenols.

Claims

1 ) A process for producing a leaf tea product comprising the step of treating fresh tea leaf with a polyphenol extraction enhancement agent selected from alkoxylated non-ionic surfactant at a concentration above the Critical Micelle Concentration (CMC), saturated hydrocarbon, enzyme with cutinase activity of at least 5 KU/g, and combinations thereof.

2) A process as claimed in claim 1 wherein there is a step of withering of the fresh tea leaf before said treatment.

3) A process as claimed in claim 1 or 2 wherein the tea leaf is macerated after said treatment when the polyphenols extraction enhancement agent is selected from alkoxylated non-ionic surfactant at a concentration above the Critical Micelle Concentration (CMC), saturated hydrocarbon, and combinations thereof.

4) A process as claimed in claim 1 or 2 wherein the tea leaf is macerated before or after said treatment when the polyphenols extraction enhancement agent is enzyme with cutinase activity of at least 5 KU/g.

5) A process as claimed in claim 3 or 4 wherein the tea leaf undergoes fermentation after maceration.

6) A process as claimed in claim 5 wherein there is a step of drying the tea leaf after fermentation.

7) A process as claimed in any one of the preceding claims wherein there is an additional step of deactivation of endogenous tea enzymes after said treatment. 8) A process as claimed in any one of the preceding claims wherein the fresh tea leaf comprises material from the plant of Camellia sinensis.

9) A process as claimed in any one of claims 1 -3 or 5-8 wherein the alkoxylated non-ionic surfactant is a polysorbate.

10) A process as claimed in any one of the preceding claims wherein the amount of surfactant added is in the range of 0.01 - 5% by dry weight of tea leaf.

1 1 ) A process as claimed in any one of 1 -3 or 5-8 wherein the number of carbon atoms in the saturated hydrocarbon is from 5 to 10.

12) A process as claimed in any one of claims 1 -2 or 4-8 wherein the enzyme with cutinase activity is added in an amount of 0.02 - 4% by dry weight of tea leaf.