Method For Processing Plant Leaves And Method For Producing A Fermented Product From Plucked Plant Leaves, Comprising Conditioning The Plant Leaves By Applying An Electric Field

Abstract

The present invention relates to a method for processing plant leaves, in particular in the context of producing a fermented product, and to a method for producing a fermented product from plucked plant leaves, comprising the steps: optionally withering the plant leaves, optionally rolling the plant leaves, optionally fermenting the plant leaves, and drying the plant leaves. In order to reduce the expenditure in costs, time and energy of conventional methods for processing plant leaves and for producing a fermented product from plucked plant leaves, respectively, it is provided according to the invention that the plant leaves are conditioned by applying an electric field.

Claims

1. Method for processing plant leaves, in particular in the context of producing a fermented product, in which said plant leaves are conditioned by applying an electric field.

2. Method according to claim 1, wherein said plant leaves are tea leaves, spice leaves, herb leaves or tobacco leaves.

3. Method according to claim 1, wherein an electric field of 0.1 kV/cm to 10 kV/cm is applied during conditioning and/or where an energy input of 0.1 kJ/kg to 10 kJ/kg is effected into said plant leaves.

4. Method according to claim 1, wherein a pulsed electric field is applied during conditioning which causes cell disruption.

5. Method according to claim 1, wherein a predetermined degree of disruption of said plant leaves is adjusted during conditioning.

6. Method according to claim 1, wherein conditioning disrupts said plant leaves non-thermally and prepares said plant leaves for a subsequent processing step of withering, rolling, fermenting and/or drying.

7. Plant leaves for the production of a fermented product which have been conditioned according to the method according to claim 1.

8. Method for producing a fermented product from plucked plant leaves comprising the steps of: optionally withering said plant leaves, optionally rolling said plant leaves, optionally fermenting said plant leaves, and drying said plant leaves, wherein said plant leaves are further conditioned according to the method of claim 1.

9. Method according to claim 8, wherein said plant leaves are conditioned prior to withering, prior to rolling, during withering, during rolling, prior to fermenting and/or prior to drying.

10. Method according to claim 8, wherein the step of conditioning replaces in whole or in part the step of withering and/or the step of rolling.

11. Method according to claim 8, wherein said plant leaves wither less than 8 hours.

12. Method according to claim 8, wherein said plant leaves are rolled less than 30 minutes, preferably less than 15 minutes and most preferably less than 10 minutes.

13. Method according to claim 8, wherein said plant leaves are fermented less than 60 minutes, preferably less than 40 minutes and most preferably less than 20 minutes.

14. Method according to claim 8, wherein said plant leaves are dried less than 30 minutes, preferably less than 15 minutes and most preferably less than 10 minutes.

15. Plant leaf product produced according to the method of claim 1.

16. Fermented product made of plant leaves produced according to the method of claim 1.

17. Method according to claim 9, wherein the step of conditioning replaces in whole or in part the step of withering and/or the step of rolling.

18. Method according to claim 9, wherein said plant leaves wither less than 8 hours.

19. Method according to claim 9, wherein said plant leaves are rolled less than 30 minutes, preferably less than 15 minutes and most preferably less than 10 minutes.

20. Method according to claim 9, wherein said plant leaves are fermented less than 60 minutes, preferably less than 40 minutes and most preferably less than 20 minutes.

Description

[0037] In the following, the invention shall be described by way of example in more detail using advantageous embodiments with reference to the drawings and subsequent trial examples. The advantageous further developments and configurations illustrated there are each independent of each other and can be combined with one another, in dependence of the requirement of the application,

[0038] where

[0039] FIG. 1 shows a flow diagram of the method steps in processing plucked tea leaves in the context of the production of a tea product;

[0040] FIG. 2 shows a flow diagram of one embodiment of a method according to the invention;

[0041] FIG. 3 shows a flow diagram of a further embodiment of the method according to the invention;

[0042] FIG. 4 shows a flow diagram of a third embodiment of the method according to the invention;

[0043] FIG. 5 shows the color change of melissa/balmn leaves (top) and mint leaves (bottom) in dependence of the energy input during conditioning according to the invention;

[0044] FIG. 6 shows the color change of a mint leaf extract in dependence of the energy input (W) during conditioning: and

[0045] FIG. 7 shows the color difference between an unconditioned tea leaf extract (U) and a tea leaf extract (PEF) conditioned according to the invention.

[0046] A conventional method for processing tea leaves and for producing a tea product from plucked tea leaves, respectively, shall below be presented with reference to the flow diagram of FIG. 1. The conventional methods for producing tobacco products are very similar. The present invention shall be explained below by way of example for processing tea leaves.

[0047] The flow diagram of FIG. 1 outlines the sequence of method steps using in the example of traditional black tea production.

[0048] After having been plucked, the tea leaves undergo the following processing stages: withering, rolling, fermenting and drying.

[0049] During the withering step, moisture is removed from the plucked tea leaves to soften them. With conventional withering, the tea leaves are exposed to temperatures of about 20 C. for a period of 18 to 24 hours

[0050] Withering is followed by the processing step of rolling. Rolling in the sense of the present invention comprises both the initial orthodox method, in which the leaves are broken open with the aid of press spindles or rollers, so that the leaking cell juice combines with the oxygen of the air. But also the CTC treatment, in which the leaf material is first broken, then torn and finally rolled, is to be included in rolling in the sense of the present invention. Conventional rolling typically takes at least 30 minutes.

[0051] With black tea, the rolled tea leaves are fermented. Fermentation of tea is an oxidation process in which oxidation and fermentation processes are initiated at elevated humidity and temperatures often above room temperature (21 C.), whereby the tea leaves of the black tea take on their copper-red to brown coloring and develop the aromas characteristic of them.

[0052] Fermentation is stopped by drying the leaf material at high temperatures above 80 C. for 20 minutes or more.

[0053] Further process steps, for example, sieving, sorting and/or mixing tea leaves, can follow drying.

[0054] The method of the invention according to a first embodiment, which is shown in the flow diagram of FIG. 2, was characterized by the fact that the tea leaves are conditioned by applying an electric field prior to withering.

[0055] For example, an electric field from 0.1 kV/cm to 10 kV/cm can be applied for conditioning, where at least 10 electric pulses, preferably 10 to 200 electric pulses and most preferably 30 to 50 electric pulses can be introduced into the tea leaves, which corresponds to an energy input of, for example, 0.1 kJ/kg to 10 kJ/kg into the tea leaves.

[0056] According to one embodiment, conditioning can be carried out in the context of a PEF method in which a pulsed electric field causing cell disruption is applied. During conditioning, a predetermined degree of disruption of the tea leaves can be set in this manner, and the degree of oxidation of the tea leaves can be controlled in this manner during the subsequent fermentation or the duration of the processing, and the processing temperatures in the subsequent processing stages withering, rolling, fermenting and/or drying can be reduced.

[0057] A second embodiment of an exemplary method according to the invention is shown in the flow diagram of FIG. 3.

[0058] The example of FIG. 3 corresponds substantially to the method of the first embodiment from FIG. 2, but differs in that, with the method of the second embodiment from FIG. 3, the step of conditioning the tea leaves does not take place prior to, but after the step of withering and prior to the step of rolling.

[0059] In the flow diagram of FIG. 4, an exemplary third embodiment of a method according to the invention is shown.

[0060] The method of the third embodiment is characterized by the fact that the tea leaves are conditioned by applying an electric field during withering.

[0061] It is just as conceivable to condition the tea leaves during rolling, or during or prior to any s processing stage prior to drying.

[0062] Repeated conditioning is also conceivable by applying an electric field in order to prepare the tea leaves selectively for the subsequent processing stage.

TRIAL EXAMPLES

[0063] In the following, exemplary trials are presented, which demonstrate that the method according to the invention leads in an advantageous manner to improved plant leaf products.

Trial Example 1

[0064] In a first trial, herb leaves as plant leaves were conditioned with an energy input at varying levels. In the trail example 1, balm leaves and mint leaves were conditioned.

[0065] FIG. 5 shows the color change in dependence of the energy input.

[0066] As can be seen in FIG. 5, the higher the energy input, the darker the plant leaves become. This is related to enzymatic (tanning) oxidation when the intra- and extracellular components react with oxygen. The present trial shows that the method according to the invention for processing plant leaves accelerates this tanning process, where it is noteworthy that enzymatic tanning begins already at a very low energy input of 0.05 to 0.1 kJ/kg. It was possible to show the same effect for a number of other plant leaves, for example, for tea leaves.

[0067] It has therefore surprisingly turned out that the method according to the invention for processing plant leaves causes an acceleration of the enzymatic oxidation process

Trial Example 2

[0068] In a further trial, plant leaves (balm leaves, mint leaves and tea leaves) processed, fermented and dried according to the invention were extracted in boiling water. For this purpose, 1 g of leaves of balm, mint and tea, processed according to the invention, were transferred into a tea bag and extracted in a measuring cup with 50 g of boiling water (100 C.) for 10 minutes. After the extraction process, the samples obtained were examined and compared.

[0069] The trial results can be seen in FIG. 6 as color differences of dried mint leaves in dependence of the energy input.

[0070] FIG. 7 illustrates the color difference of fermented non-processed tea leaves and those processed according to the invention.

[0071] FIGS. 6 and 7 show that the method according to the invention accelerates the extraction of color and flavoring ingredients from the plant leaves, which is reflected in stronger tanning of the plant leaf extract.

[0072] The higher the specific energy input, the better the ingredients of the tea leaf product can be extracted.

[0073] The visual results were also confirmed in a sensory taste test, which showed that conditioning according to the invention leads to a more intense taste of the plant leaf extract. The higher the specific energy input, the more intense the taste of the plant leaf product.