WO1997044437A1

WO1997044437A1 - Method of producing red wine

Info

Publication number: WO1997044437A1
Application number: PCT/IL1997/000157
Authority: WO
Inventors: Arkadi Papikian; Alla Papikian
Original assignee: Arkadi Papikian; Alla Papikian
Priority date: 1996-05-20
Filing date: 1997-05-15
Publication date: 1997-11-27
Also published as: AU2649697A; IL118338A0

Abstract

The invention presents a new method of fermenting the must of red grapes during the production of red wines. The new method is based upon changing the composition of the must during alcoholic fermentation by means of removing the sediments from the bottom of the fermentation vat during fermentation. These sediments are comprised primarily of grape seeds and solid particles of pomace. This operation reduces the extraction of tannins from the grape seeds, particularly during the punching down of the cap or the mixing of the fermenting must, thereby obtaining wine with optimum astringency. The astringency of the press wine is also reduced thereby requiring no additional treatment and rendering it more economical to produce. Finally, this method provides the ability to extend the contact of the fermenting juice and the young wine with the grape skins without risk of producing wine with too much, and not optimal, astringency.

Description

METHOD OF PRODUCING RED WINE

The invention described in this document applies to the field of wine production. More specifically to the methods of fermenting red grape must. For the purpose of this document the fermentation of red grapes implies fermentation of the mixture of grape juice, stem fragments, grape skins, seeds and pulp (collectively called the "must").

The technology of red table wine production is based on the extraction by the fermenting juice of a number of elements from the solid components of the must, which determine the color, aroma, varietal character and astringency. The astringency of the red wine is a function of the amount of tannins which are extracted from the skins and primarily from the seeds.

The classic technology for producing red table wine comprises of the following operations:

1 - Crushing the grapes, thereby splitting the skins, releasing the juice thereby enabling yeast activity and fermentation.

2 - Removing the stems and leaves in order to avoid excessively high tannin levels in the wine.

3 - Introducing an active yeast starter into the must.

4 - Fermenting the must with multi-mixing of the fermenting juice and the cap that forms at the top of the fermentation vat during fermentation and consists of solid grape particles.

5 - Removal of the free-run wine from the fermentation vat.

6 - Pressing the grape mass, or pomace. The resulting "press wine" is high in tannins and color pigments. The volume of press wine produced is usually between 15 and 25% of the total volume of wine produced.

There is a known method of producing red wine in which the fermenting must is held in the fermentation vat until a cap of solid components of the must forms at the top of the fermentation vat as a result of alcoholic fermentation. Then the formed cap is punched down into the fermenting must in order to mix them. This activity of holding and punching down the cap may occur a number of times (usually 3 to 6 times per day) during the fermentation process (usually 4 to 12 days) until the preset parameters have been obtained. At this point the wine is drawn off from the fermentation vat. Finally the sediment of seeds and other solid particles that formed on the floor of the vat during the fermentation process, together with the cap are transferred to a wine press in order to remove the press wine.

The main problem with this method is the extraction of excessive quantities of tannins originating from the seeds. These tannins also add to the astringency of the wine, but also contribute unpleasant, and sometimes undesirable bitterness.

The authors of this invention have experimentally proved that tannins are extracted most intensively in the course of mixing the fermenting must with the cap of grape skins formed at the top of the fermentation vat during fermentation. In addition, the wine produced after pressing (the "press wine") is characterized by excessive astringency and requires additional treatment thus decreasing the efficiency of wine production. The object of the invention is to develop a method of fermenting the must of red grapes in which it is possible to reduce the extraction of tannins from the seeds thereby obtaining wine with optimum astringency. In addition, the astringency of the press wine is also reduced thereby requiring no additional treatment and therefore more economical to produce.

The set task is achieved by maintaining the mixture of must and yeast starter in the fermentation tank until a cap solid particles, comprising primarily of grape skins, forms at the top of the fermentation vat as a result of alcoholic fermentation. The formed cap is then punched down and mixed with the fermenting juice. Prior to punching the cap down, once again, into the fermenting juice, the sediment which has formed at the bottom of the fermentation vat is removed. The sediment comprises primarily of grape seeds and other solid particles of pomace. The operations of holding and punching the cap down into the must, and removing the sediment from the bottom of the fermentation vat are repeated until the preset parameters of the wine are obtained. Once the preset parameters have been obtained the wine is separated from the solid particles.

The essence of the invention is illustrated in the following figures: Note: Figures 1 and 2 refer to traditional upright fermenters and Figures 3 and 4 refer to rotary fermenters.

Figure 1 schematically shows the traditional fermenter for must fermentation in accordance with the proposed method, filled with the initial mixture (grape must and yeasts).

Figure 2 shows the mixture during fermentation. The cap that has formed at the top of the fermentation tank is being punched down, and, sediment comprising primarily of grape seeds and other solid particles have formed at the bottom of the tank.

Figure 3 schematically shows the rotary fermenter for must fermentation in accordance with the proposed method, filled with the initial mixture (grape must and yeasts).

Figure 4 shows the mixture during fermentation. The cap that has formed at the top of the rotary fermenter is being mixed with the fermenting juice by rotation, and, sediment comprising primarily of grape seeds and other solid particles have formed at the bottom of the tank. Method of Operation

1 - The fermentation tank (1) as seen in Fig 1 and Fig 3 is filled to about 80% of capacity with the red grape must.

2 - Active yeast starter is then added.

3 - The mixture of must and active starter (2) is mixed by the use of the two plungers (3) as in Fig 1, or by rotation as in Fig 3 and is left to ferment.

4 - During fermentation the fermenting juice extracts from the solid particles of the must (primarily from the seeds) the tannins which determine the astringency of the wine. The fermenting juice also extracts other elements which determine the color, density, aroma and other varietal characteristics.

5 - Carbon dioxide gas, escaping during the course of fermentation causes flotation of grape skins and pulp, together form the cap (4) as seen in Fig 2 and in Fig 4.

6 - Denser material, comprising of primarily of the grape seeds settle at the bottom of the fermentation tank and form a sediment (5).

7 - At this stage there are three different matter levels in the fermentation tank: the cap (4), fermenting must (6) and sediment (5).

8 - After the first formation of the cap (10 to 24 hours following the filling of the fermentation tank) the sediment expulsion valve, (7) in Fig 2 and in Fig 4, is opened. Once the sediment (5) has been drawn off, the valve must then be closed.

9 - The cap (4) is then mixed with the fermenting must (6) by punching down the cap or rotation of the tank. 0 - During the further fermentation of the must, the quantity of tannins extracted will be reduced due to the decreased content of grape seeds. 1 - After the next holding, when the cap forms again, the sediment is removed by opening the sediment expulsion valve, (7) in Fig 2 and in Fig 4. When the sediment has been removed the valve is closed and the cap is mixed with the fermenting juice by punching down the cap or rotation of the tank. 2 - The above operations (as described in paragraph 11) is repeated 1 to 6 times per day during the 4 to 12 days of fermentation, until the young wine obtains the preset parameters.

Thus permanent decrease in the content of grape seeds is obtained in the fermentation vat and consequently a decrease in the extraction of tannin, which prevents excessive astringency in the wine. It is important to carry out the removal of the sediment (5) from the fermentation vat prior to punching the cap and mixing it with the fermenting must, since, as it has been experimentally proven by the authors of the invention, the most intensive extraction of the tannins occur during the punch down and mixing process. In addition, in order to decrease any loss of wine it is expedient to separate the fermenting must (6), flowing out of the fermentation tank during sediment removal, from the removed sediment (5) with the use of any known method and to return the must back to the fermentation tank.

The young wine is removed from the fermentation tank via the expulsion valve, (9) in figure 2 and in figure 4, for further storage or treatment. The sediment, composed primarily of grape skins is removed via the fermentation vat door (8) for pressing.

The press wine produced under the proposed method features lower astringency as compared with conventional known methods. This is accounted for by the decreased content of grape seeds in the pressed sediment mass.

GLO S SARY

CAP The mass of grape skins which accumulates at the top of the fermentation vat, above the juice, during fermentation.

FREE-RUN Juice or wine which drains out of the fermentation vat under the natural weight of the fruit, without pressing. Widely considered to be of better quality that the press wine. Consists of 60 to 70 percent of the total juice available.

MACERATION Refers to the period during which the must or wine remains in contact with the grape skins. Alcohol acts as a solvent, extracting color, tannins and aroma from the skins. Extended contact also extracts bitter tannins from the grape seeds.

MUST The mixture of grape juice, stem fragments, grape skins, seeds and pulp derived from crushing the grapes prior to fermentation.

POMACE Residue of stem fragments, skins, seeds and dead yeast cells left after fermentation.

PRESS WINE Dark red wine squeezed from the pomace after the free run has been drained off. Inferior to free-run wine and often extremely tannic. Consists of 30 to 40 percent of total juice available.

TUMPING OVER refers to fermenting must being drawn over the cap of the skins that have formed at the top of the fermentation vat.

TANNINS A group of chemicals found in grape skins, seeds and stems that confer astringency and bitterness to the taste of the wine and play a major role in the ability of the wine to age.

Claims

Claims :

The method for the production of red wine according to which the mixture of grape must and starter is held in the fermentation vat until a cap of solid particles forms at the top of the fermentation vat as a result of alcoholic fermentation, the formed cap is then mixed with the fermenting must. This process of holding and mixing is repeated until wine with the preset desired parameters is obtained. The wine is then separated from the solid particles of the must. Prior to mixing the formed cap with the fermenting must, the sediment of grape seeds and other solid particles is removed.

2. The operation of removing the grape seeds and other solid particle sediment, as described in paragraph 1 above, is implemented directly prior to the next punching of the cap and mixing it with the fermenting must.

3. The method according to paragraphs 1 and 2, from the sediment of seeds and other solid particles which have been removed from the fermentation tank, fermenting must is separated and returned to the fermentation tank.

4. The method, as indicated above, is described in detail in the specifications enclosed.