WO2024126448A1

WO2024126448A1 - Low-alcohol fermented beverages with wine flavor

Info

Publication number: WO2024126448A1
Application number: PCT/EP2023/085273
Authority: WO
Inventors: Claudia BORGMEIER; Esther Gabor; Guido Meurer; Anna Zimmermann; Wolfgang W. SCHAEFER; Hans-Peter HOEHNEN
Original assignee: BRAIN Biotech AG
Priority date: 2022-12-13
Filing date: 2023-12-12
Publication date: 2024-06-20

Abstract

Suggested is a low-alcoholic fermented beverage, obtainable or obtained by the following steps: (a) providing leaves from untreated grape vines; (b) subjecting the leaves from step (a) to a treatment with, water, grape juice, alcohol-free wine or mixtures thereof to obtain an infusion; (c) optionally removing the leaves and/or supplementing the infusion of step (b) with a source of a carbohydrate; (d) subjecting the infusion of step (b) or (c) to fermentation by adding a working amount of at least one micro-organism capable of inducing fermentation to obtain a fermentation product; (e) removing the liquid supernatant from the solid residue; and optionally (f) adding further aroma compounds and additives to said liquid of step (d), wherein fermentation is conducted under microaerobic or aerobic conditions.

Description

Low-alcohol fermented beverages with wine flavor

AREA OF THE INVENTION

[0001] The present invention belongs to the area of wine-like beverage based on fermented grape vine leaves with low alcohol content and a method of producing the same.

TECHNOLOGICAL BACKGROUND

[0002] Grape vine leaves have a long history of use for consumption, e.g., as stuffed vine leaves or generally as green vegetables. Also, the preparation of grape vine leaf tea is widely known and valued for its health benefits, such as preventing metabolic diseases, as well as potential applications as antioxidant in food products. Yet, the flavor profile is crucial for the consumers acceptance of vine teas, therefore natural fermentation is frequently applied as a means of taste improvement. The aromatic profile of a fermented beverage is considered a major factor in determining its perception by the consumer thereof. This is particularly relevant in the case of fermented products from leaves, in this case grape vine leaves.

[0003] The vast majority of wine is made from Vitis vinifera varieties that are highly susceptible to fungal diseases and pests, making plant control difficult for growers. Depending on the growing area, 20-70% of organic growers declare issues with fungal diseases in Europe. Recently, fungus-resistant grape (FRG) varieties have been introduced as the most suitable choice in organic viticulture, especially in areas where disease pressure necessitates high rates of fungicides. FRG varieties contribute to improved disease management in organic as well as conventional viticulture, reduce production costs and decrease copper accumulation in soils. In the last two decades, many FRG varieties presenting advantageous agronomic attributes and oenological characteristics have been developed in Europe and northern America for conventional and sustainable farming. It has been found that the leaves of some FRG varieties have a pleasant taste, when the leaves itself are consumed e.g., as filled wine leaves, which is comparably attractive as the one of grape vine varieties used for the preparation of tea (Vitis caribae).

[0004] The aromatic profile of a fermented beverage is the result of a complex process of aroma development having numerous variables and inputs from the plant source. These variables include the particular grape vine leaves, the particular strain of yeast and bacteria responsible for the fermentation and various methods of preparing the beverage.

[0005] To date, the complex processes involved in the development of the aromatic profiles of fermented beverages are not fully understood. Methods to produce a desired aromatic profile in the end product are limited and remain a significant topic of research. i RELEVANT STATE OF THE ART

[0006] US 10,233,414 B2 (UNIV STELLENBOSCH) relates to an alcoholic fermented beverage from grape juice or other juices, such as wine or cider. The use of crushed vine leaves to modulate the aromatic profile of the beverage is also suggested.

[0007] WO 2022/080507 A1 (SUNTORY HOLDINGS LTD) relates to fermented plant infusions such as a kombucha-like beverage comprising low amounts of acetic acids and reduced alcohol content, wherein the plant material is derived from Ilex and/or Paullinia.

PROBLEM TO BE SOLVED

[0008] The object of the present invention has been providing a beverage with flavor and mouthfeel similar to white, red or rose wines, which however, is significantly reduced in alcohol.

DESCRIPTION OF THE INVENTION

[0009] In a first embodiment the present invention refers to low-alcoholic fermented beverage, obtainable or obtained by the following steps:

(a) providing leaves from untreated grape vines;

(b) subjecting the leaves from step (a) to a treatment with,

(bl) water,

(b2) grape juice,

(b3) alcohol-free or low-alcohol wine, or mixtures thereof to obtain an infusion;

(c) optionally

(cl) removing the leaves and/or

(c2) supplementing the infusion of step (b) with a source of a carbohydrate;

(d) subjecting the infusion of step (b) or (c) to fermentation by adding a working amount of at least one microorganism capable of inducing fermentation to obtain a fermentation product;

(e) removing the liquid supernatant from the solid residue; and optionally

(f) adding further aroma compounds and additives to said liquid of step (d).

[0010] Low-alcohol in the context of the present invention has the meaning of an alcohol content below 5%, preferably below 1.0%, more preferably below 0.5%. The latter means that the product can be branded as being "free of alcohol". Another task has been reducing the supplemental nutrients in the fermentation step, particularly avoiding the addition of nitrogen compounds.

[0011] Another object of the present invention relates to a process for obtaining a low-alcoholic fermented beverage, comprising or consisting of the following steps:

(a) providing leaves from untreated grape vines;

(b) subjecting the leaves from step (a) to a treatment with,

(bl) water,

(b2) grape juice,

(b3) alcohol-free or low-alcohol wine or mixtures thereof to obtain an infusion;

(c) optionally

(cl) removing the leaves and/or

(c2) supplementing the infusion of step (b) with a source of a carbohydrate;

(e) removing the liquid supernatant from the solid residue; and optionally

(f) adding further aroma compounds and additives to said liquid of step (d).

[0012] Surprisingly it had been found that from vine leaf infusions, fermentation can be used to prepare a tasty beverage that has a flavor profile similar to wine, but unlike wine, is characterized by an extremely low alcohol content. By selection of the right organisms/consortia specific wine-like flavor profiles are obtainable. Unlike in wine production, using anaerobic fermentation, the process according to the present invention takes preferably place under micro- aerobic or aerobic conditions. While a source of carbon needs to be added to fermentation, typically a carbohydrate, by surprise the infusion of the leaves serves as the nitrogen source.

[0013] Another major advantage of the invention is related to the use of a by-product or waste stream from winemaking to make a new product, which is associated with a positive sustainability effect (i.e., intermediate storage of CO2, sustainable business concept because of dual use of agricultural land and equipment at the winemaker's site). In particular, the proper selection of leaves for the infusion and microorganisms for fermentation along with the process control allows manufacturing beverages which come close to the taste and mouthfeel of wine, however being substantially free of alcohol. Beverages with reduced alcohol content are increasingly requested by consumers due to health reasons or general acceptance issues of alcoholic beverages. By varying suitable yeasts, additionally applying different microorganisms - such as fungi or bacteria - and modifying fermentation parameters the taste can be modulated to please the consumers' sense of taste.

Selection of leaves

[0014] Leaves of vine grapes are according to the present invention need to be untreated, which means that they have not been in contact with insecticides or fungicides. Thus, the preferred leaves are those obtained from fungus-resistant grape varieties (abbreviated "FRGV") are encountered more and more frequently in the vineyards. They are bred grape varieties that are resistant to some of the greatest challenges in modern viticulture. These are the fungal attacks of powdery mildew and downy mildew. Since grapevine is the crop that is most frequently sprayed for fungal infestation, FRGVs have a distinct advantage over conventional grape varieties. They no longer need to be sprayed at all, or only rarely. This is why they are being used more and more frequently, especially in organic farming, and are also an important component of the so-called "Delinat" method which understands a vineyard as an ecosystem. The preferred FRGV whose leaves are used for preparing the initial infusion are selected from Cortis, Pinotin, Regent, Muscaris, Souvignier Gris, Chardonel, Solaris, Phoenix, Bianca, Johannite, Saphira or mixtures thereof, all of them representing sub-species of Vitis vinifera. The most preferred variety is Muscaris (FR 493-87; Freiburg 493-87.) Besides Vitis vinifera, also other FRGV are cultivated and used for consumption, one example is Vitis caribae, a vine breed that is cultivated in tropical climate zones.

Preparation of the infusions

[0015] Grape vine leaves may be used directly after harvest or after a drying step. To facilitate the preparation of an infusion, grape vine leaves may be at least partially crushed or fragmented. Any convenient method can be used to achieve this. The grape vine leaves are then immersed in water at a concentration of 5 to 70 % (w/v), more preferably, 10 to 50% and even more preferably 20 to 40%. Instead of water it is also possible to prepare the infusion from grape juice or non-alcoholic wine or mixtures thereof.

[0016] Enzymes can be added at this stage to improve the production of the infusion. The fermentable mixture may also be agitated prior to subjecting it to fermentation. Any suitable form of agitation may be used, including mechanical agitation by means of an impeller or similar device. The preparation of the infusion is carried out at a temperature of about 10 to about 50 °C and preferably of about 18 to about 40 °C.

[0017] A further feature of the invention provides for the method to include the additional step of processing the infusion before fermentation by pressing and / or filtration to remove residual plant material. The infusion is optionally sterilized or pasteurized before adding the fermentation microorganism. Optionally, the preparation of the grape vine leaf infusion can be optimized by adding suitable enzymes, e.g., cellulases or pectinases. In some embodiment the duration of the aqueous infusion is 1-3 days. Furthermore, the infusion is characterized in that its pH is below 7, more preferred below 5, even more preferred below 4.

Microorganisms

[0018] The fermentation of the infusions of the grape vine leaves takes place in the presence of one or more microorganism capable of inducing fermentation selected from yeast, fungi and bacteria. The microorganisms may consist of individual strains or consortia or a mixture of at least one yeast and at least one bacterium and/or at least one fungus. Inoculation can take place in one step or sequential of one or two or more strains.

[0019] In some embodiments of the invention, the microorganism used to ferment the infusion is, or comprises, a yeast, for example a yeast of the family Saccharomycetaceae.

[0020] In some embodiments of the invention, the microorganism is, or comprises, a yeast selected from: Saccharomyces spp.; Pichia spp:, Zygosaccharomyces spp:, Kluyveromyces spp:, Kloeckera spp:, Kazachstania spp.; Brettanomyces spp:, Metschnikowia spp:, Aureobasidium spp:, Issatchenkia spp:, Torulaspora spp:, Lachancea spp:, Hanseniaspora spp:, Cyberlindnera spp.; and Meyerozyma spp. or a combination thereof. In some embodiments, the microorganism is a yeast selected from Saccharomyces spp.; Kluyveromyces spp.; Zygosaccharomyces spp.; Pichia spp.; Cyberlindnera spp.; and Meyerozyma spp:, or a combination thereof. In some embodiments, the microorganism is, or comprises, a yeast selected from: S. cerevisiae; S. uvarum; S. bayanus; S. exiguus; S. carlsbergensis; T. delbrueckii; Lachancea thermotolerans; P. anomala; P. kluyveri, P. caribbica; P. guilliermondii; Z. bailir; K. marxianus; K. lactis; M. pulcherrima; A. pullulans; I. orien- talis; K. apiculata; C.javanica; H. uvarum; H. osmophilia, or a combination thereof.

[0021] In some embodiments, the microorganism used for the fermentation comprises one or more yeasts selected from: Saccharomyces cerevisiae, Kluyveromyces lactis, Kluyveromyces marxianus, Kluyveromyces marxianus fragilis, Pichia membranifaciens, Pichia kluyveri, Cyberlindnera jadinii, Torulaspora delbrueckii, Kazachstania unispora, Kazachstania servazii, Kazachstania turicensis, Torulaspora delbrueckii, Dekkera bruxellensis, Wickerhamomyces anoma- lus, and Hanseniaspora uvarum. In some embodiments, the microorganism used for the fermentation comprises one or more yeasts selected from: Kazachstania unispora, Kazachstania servazii and Pichia membranifaciens.

[0022] In some embodiments, the microorganism used for the fermentation comprises a combination of a yeast selected from Saccharomyces cerevisiae, Kluyveromyces lactis, Kluyveromyces marxianus, Zygosaccharomyces rouxii, Pichia membranifaciens, Cyberlindnera jadinii, and Meyerozyma guilliermondii, with at least one bacterium, preferably a lactic-acid producing bacterium as set out above.

[0023] In some embodiments, the microorganism used for the fermentation comprises a combination of a yeast and at least one lactic-acid producing bacteria, for example a bacteria selected from L. acidophilus, L. fructivorans, L. gasseri, Ljensenii, L. delbrueckii, L. delbrueckii subsp. Bulgariens, L. amylovorus, L, crispatus, and L. helveticus, preferably selected from Lactobacillus acidophilus, Lactobacillus fructivorans, and Lactobacillus delbrueckii, or a fungus such as for example Ustilago maydis.

[0024] In a particular preferred embodiment, the microorganisms represent a mixture of at least two yeasts, wherein the first yeast is Saccharomyces cerevisiae or Torulaspora delbrueckii and any further yeast is selected from the group consisting of Kazachstania unispora, Ka- zachstania servazii and Pichia membranifaciens.

[0025] These yeasts, particular in combination with infusions of leaves of Muscaris or Vitis caribae leads to products with significantly low alcohol content and full wine taste.

Fermentation

[0026] Said microorganisms may already be added immediately to the infusions or after pressing and/or filtration of the infusion and, optionally, pasteurization. In some embodiment the fermentation microorganisms are added to the aqueous infusion in a concentration of 10^A5 to 10^A8 cfu/ml, more preferred 10^A6 to 10^A7 cfu. For fermentation the mixture of infusion and microorganism is preferably incubated between 12 hours and 28 days, preferably less than 14 days, more preferred 1 -7 days, more preferred 1 -4 days, even more preferred for 48-72h, most preferred for48h. The fermentation temperature is preferably between 10 and 30°C, most preferred 18°C. Fermentation takes place under microaerobic or aerobic conditions for example, by shaking incubation, alternatively sparging with air or oxygen (minimum 1 mg/L dissolved oxygen), preferably at temperatures ranging from about 5 to about 50 °C, preferably from about 15 to about 40°., more preferably from about 18 to about 30 °C.

[0027] In a preferred embodiment a source of carbohydrate, such as for example sucrose, glucose, fructose or grape juice, is added to the fermentable mixture at concentrations of up to 50g/l, more preferably below 30 g/l and even more preferably between 10 and 25g/l. In case the leaves are not separated of and stay in the infusion during fermentation, supplementation with additional carbohydrates is not necessary. Further additives which can be supplemented during fermentation encompass for example yeast nutrients (ammonium chloride, yeast cell wall, autolyzed yeasts, inactivated yeasts and the like.

[0028] In a preferred embodiment, fermentation with more than one microorganism may take place separately, sequentially or simultaneously.

[0029] In some embodiments, fermentation with more than one microorganism takes place simultaneously. For example, in some embodiments two or more yeasts are added, together, to the stevia infusion and fermentation by each occurs concurrently. In other embodiments, one or more yeasts and one or more bacteria are added together to the grape vine leaf infusion (dual inoculum) and fermentation by each occurs concurrently.

[0030] In some embodiments, fermentation with more than one microorganism takes place sequentially. For example, fermentation may be carried out first with one or more yeasts and, subsequently, further fermentation may be carried out with one or more bacteria or fungus, or combination of bacteria and fungi. Alternatively, fermentation may be carried out first with one or more bacteria and, subsequently, further fermentation may be carried out with one or more yeasts.

[0031] Also, a rehydrated yeast mixture may be added to the fermentable mixture before subjecting the fermentable mixture to fermentation. This may occur in any suitable manner and the amount added may be calculated based on known dosing requirements. The rehydrated yeast mixture may include active dry wine yeast and a yeast rehydration nutrient.

[0032] An advantageous feature of the present invention is that, depending on the choice of microorganism(s) and on the process conditions used, a variety of different fermented beverages, having different properties -including but not limited to sensory properties such as taste, appearance, aroma and mouthfeel- are accessible from the grape vine leaf plant material.

[0033] Typically, the duration of fermentation is determined by the consumption of the carbohydrate feedstock (i.e., the sugar). This can be monitored by methods which are known in the art. The aim is to reduce the sugar level in the infusion (the fermentation medium) to zero, or as close as possible to zero.

[0034] Finally, the product of fermentation is optionally processed further, for example the fermented mixture is optionally pasteurized, filtered, cleared (preferably by means of enzymes) and bottled, as may be appropriate or desired by the artisan.

[0035] The microorganisms still contained in the fermentation product can also serve as yeast storage for an improved mouthfeel. For this purpose, the pasteurized fermentation product is stored in the refrigerator for up to 3 months and only then the yeasts are decanted or filtered off.

INDUSTRIAL APPLICATION

[0036] While the fermentation product, optionally after further processing as explained above, may serve as the beverage alone, it advisable adding further aroma compounds and auxiliary agents, such as for example grape juice, tannins, citric acid and the like.

[0037] The description of the present invention discloses specific preferred embodiments, for example with respect to certain combination of components, their ratios, process conditions and the like. For the avoidance of doubts, it is emphasized, that combinations of preferred embodiments will result in more preferred embodiments and thus, are hereby disclosed without the need to be expressed literally once again. EXAMPLES

Example 1

Preparation of an infusion from untreated grape vine leaves

An infusion of fungus-resistant grape vine leaves to be used according to the present invention was obtained according to the following protocol:

1) fresh grape vine leaves and saplings were collected from vine plants and immediately immersed in 18 to 20°C water (2.5 to 4 kg/25L);

2) the infusions were incubated in airtight containers at 18 to 20°C for 48h;

3) the supernatant was decanted. Optionally, the leaves were pressed in a hydraulic press (3 bars) and the extract collected and mixed with the supernatant;

4) the supernatant was pasteurized at 85°C for 10 min and immediately cooled down to <40°C in ice water; and

5) the infusion was immediately applied for fermentation or alternatively stored at 6-8°C until use.

Example 2

Selection of microorganisms for fermentation

The following microorganisms/yeasts were found particular useful for conducting the fermentation according to the present invention:

• Saccharomyces cerevlslae

• Torulaspora delbrueckll

• Kazachstanla unlspora

• Plchia membranlfaclens

• Kluyveromyces marxlanus

• Kluyveromyces marxlanus fragllls

• Kazachstanla turlcensls

• Dekkera bruxellensls

• Kazachstanla servazll

• Wlckerhamomyces anomalus

• Hansenlaspora uvarum

• Plchia kluyverl • Kluyveromyces lactls

• Cyberllndnera Jadlnll

Example 3

Culturing and preparation of microorganisms for fermentation

A yeast cell suspension to be used according to the present invention was obtained according to the following protocol:

1) active dry yeast was resuspended in water (40°C) to obtain a titre of 5E+08 CFU/ml and the suspension is incubated at 25°C for 30min and the fresh yeast cell inoculum was prepared as follows:

2) shake flask cultures (50ml YPD in 500ml baffled flasks, silicose stoppers) are inoculated with 3 yeast colonies (grown on YPD agar at 28°C for 48h).

3) incubate cultures at 28°C 180 rpm for 48h and subsequently harvest them by centrifugation.

4) resuspend yeast cells in a smaller volume of spent medium to obtain a final titre of 5E+08 cfu/ml.

5) apply yeast cell suspensions immediately for inoculation of grape vine leaf infusion according to Example 1.

Example 4

Protocol - Fermentation "A"

1) Shake flasks (300ml baffled, silicose stopper) containing 120ml Muscaris infusion (supplemented with Sucrose 25g/L) were inoculated with yeast strain Pichia membrani- faciens DSM70366 (1 E+07 cfu/ml)

2) Shake flasks were incubated at 18°C, 100rpm for 72h.

3) Fermented infusion including yeast cells was transferred to 250ml glass bottles and pasteurized in a water bath at 75°C for 15min. Bottles were allowed to cool to room temperature and subsequently stored at 6 to 8°C for 48 h to 30 days. Fermented infusion was subsequently centrifuged and supernatant decanted into a new bottle. Alternatively, fermented infusion was centrifuged immediately after pasteurization and supernatant was decanted and transferred into a new bottle. Example 5

Protocol - Fermentation "C"

1) Shake flasks (300ml baffled, silicose stopper) containing 120ml Muscaris infusion (supplemented with Sucrose 25g/L) were inoculated with yeast strains Kazachstania unispora (1 E+07 cfu/ml) and S. cerevisiae (1 E+06 cfu/ml).

2) Shake flasks were incubated at 18 °C, 100 rpm for 48 h.

3) Fermented infusion including yeast cells was transferred to 250 ml glass bottles and pasteurized in a water bath at 75 °C for 15 min. Bottles were allowed to cool to room temperature and subsequently stored at 6 to 8 °C for 48h to 30days. Fermented infusion was subsequently centrifuged and supernatant is decanted into a new bottle. Alternatively, fermented infusion was centrifuged immediately after pasteurization and supernatant decanted and transferred into a new bottle.

Example 6

Protocol - Preparation of a beverage

1) Fermented, pasteurized infusion (prototype C) is supplemented with grape juice, tannins, citric acid to obtain a beverage product

2) The beverage product is transferred to glass bottles, sealed, pasteurized (85°C, 10min) and immediately cooled to <40°C in ice water.

In order to ascertain the perceived aromatic components to the user, a sensory experiment was performed. The 8 panelists were asked to rate the beverages in comparison to four commercially available de-alcoholized wines (C1 -C4) (price range between 4.5 and 13 EUR/750 ml bottle), with regard to appearance, aroma, taste, mouthfeel and aftertaste on a scale ranging from 1 = best to 5 = worst). The results are shown in Table 1; provided are the average values from the data set for each product. As one can see, the product according to the present invention was rated by far best.

Table 1

Sensory assessment

Example 7

Protocol - Mash Fermentation

Instead of an infusion as disclosed in Example 1, a mash of fungus-resistant grape vine leaves to be used according to the present invention was obtained according to the following protocol:

1) Mash from untreated grape vine leaves was prepared by immersing Muscaris leaves in 18 to 20 °C water (30 to 80 g/L). Mash samples were either pre-pasteurized (as described in Example 1) or inoculated with yeast cells immediately without pasteurization.

2) Shake flasks (500ml baffled, silicose stopper) containing 200ml Muscaris mash (supplemented with sucrose 25g/L) were inoculated with yeast strains Kazachstania unispora (1 E+07 cfu/ml) and S. cerevisiae (1 E+06 cfu/ml).

3) Shake flasks were incubated at 18 °C, 100 rpm for 48 h.

4) Fermented mash including yeast cells was transferred to 250 ml glass bottles and subsequently centrifuged. The supernatant was decanted into a new bottle and pasteurized in a water bath at 75 °C for 15 min. Bottles were allowed to cool to room temperature and subsequently stored at 6 to 8 °C.

5) Samples (5ml) were taken at the start and end of fermentation, briefly centrifuged and assessed for Brix and OD. Ethanol of the final fermented infusion was assessed with a commercial kit (Megazymes) according to the manufacturer's instructions.

The results are shown in Table 2; provided are the values for sugar content (Brix), biomass (OD) and alcohol production (ethanol) at the start of the fermentation and after 48 hours for each fermentation set-up in shake flasks in a volume of 200 ml, respectively.

As can be deduced from the table, yeast activity is comparable in the pasteurized or nonpasteurized mash fermentation and sugar is reduced to the same extent in both settings. Ethanol production was slightly higher than in the fermentation with infusions from leaves as in Example 1. A pleasant Muscaris aroma was observed for all mash fermentation trials as evaluated by olfaction.

Therefore, mash fermentation is a suitable method for winemakers to make use of the leaves directly after harvest without prior treatment. Table 2

Fermentation of mash from Muscaris vine leaves

Claims

WHAT CLAIMED IS

1. A low-alcoholic fermented beverage, obtainable or obtained by the following steps:

(a) providing leaves from untreated grape vines;

(b) subjecting the leaves from step (a) to a treatment with,

(bl) water,

(b2) grape juice,

(c) optionally

(cl ) removing the leaves and/or

(c2) supplementing the infusion of step (b) with a source of a carbohydrate;

(e) removing the liquid supernatant from the solid residue; and optionally

(f) adding further aroma compounds and additives to said liquid of step (d), wherein fermentation is conducted under microaerobic or aerobic conditions.

2. The beverage of Claim 1, showing an alcohol content of less than 5 wt. -percent.

3. A process for obtaining a low-alcoholic fermented beverage, comprising or consisting of the following steps:

(a) providing leaves from untreated grape vines;

(b) subjecting the leaves from step (a) to a treatment with,

(bl) water,

(b2) grape juice,

(c) optionally

(cl ) removing the leaves and/or

(c2) supplementing the infusion of step (b) with a source of a carbohydrate;

(d) subjecting the infusion of step (b) or (c) to fermentation by adding a working amount of at least one microorganism capable of inducing fermentation to obtain a fermentation product; (e) removing the liquid supernatant from the solid residue; and optionally

4. The process of Claim 3, wherein said leaves are leaves of fungus-resistant grape vines.

5. The process of Claim 4, wherein said leaves are leaves of grape vines selected from the group consisting of Cabernet Jura, Cabernet Blanc, Cabertin, Cabernet Cortis, Pi- notin, Regent, Muscaris, Souvignier Gris, Chardonel, Solaris, Phoenix, Bianca, Johanniter, Saphira, Vitis caribae or mixtures thereof.

6. The process of Claim 4, wherein said leaves are leaves of Muscaris or Vitis caribae.

7. The process of Claim 3, wherein said aqueous treatment is conducted at a temperature of from about 5 to about 50 °C.

8. The process of Claim 3, wherein said infusions are supplemented with sucrose, glucose, fructose or grape juice.

9. The process of Claim 3, wherein said microorganisms are yeasts, fungi or bacteria, taken as individual strains or consortia or mixtures of at least one yeast and at least one bacterium and/or at least one fungus.

10. The process of Claim 3, wherein said microorganisms are selected from the group consisting of

• Saccharomyces cerevisiae

• Torulaspora delbrueckii

• Kazachstania unispora

• Pichia membranifaciens

• Kluyveromyces marxianus

• Kluyveromyces marxianus fragilis

• Kazachstania turicensis

• Dekkera bruxellensis

• Kazachstania servazii

• Wickerhamomyces anomalus

• Hanseniaspora uvarum

• Pichia kluyveri

• Kluyveromyces lactis

• Cyberlindnera jadinii or mixtures thereof.

11. The process of Claim 3, wherein said microorganisms represent a mixture of at least two yeasts, wherein the first yeast is Saccharomyces cerevisiae or Torulaspora del- brueckii and any further yeast is selected from the group consisting of Kazachstania unispora, Kazachstania servazii and Pichia membranifaciens.

12. The process of Claim 3, wherein said microorganisms are added to the aqueous infusion in a concentration of about 10^A 5 to about 10 ^A8 cfu/ml.

13. The process of Claim 3, wherein fermentation is conducted at temperatures ranging from about 15 to about 50 °C.

14. The process of Claim 3, wherein the fermentation product is further processed for example by pasteurization, filtration, clearing and filling into bottles.