Field of the invention

The present invention relates to the use of a gum against haze in wine.

Background of the invention

The production of wine is characterised by the following steps which are well known to those skilled in the art: a) extracting wine must from grapes; b) subjecting the wine must to fermentation under the action of yeast to yield wine which is subsequently separated from solid residues; c) optionally subjecting the wine to aging and d) bottling or packaging the wine.

The formation of potassium tartrate (KHT) crystals is a major problem in wine. Tartaric acid is the main organic acid produced by the grape berry during its development. It is solubilised in the form of potassium and calcium salts into grape musts during the processing of berries. During the fermentation, the solubility of salts of tartaric acid decreases with the increase of ethanol concentration (due to the fermentation of sugars). A well-known solution to prevent the formation of KHT crystals is to add a wine stabiliser such as mannoproteins. Mannoproteins are, together with glucan, the main component of cell walls in yeasts (Lipke P.N. et al, J. Bacteriol. (1998) 180(15): 3735-3740). Another major problem in the production of wines is the formation of haze. A hazy wine means that the wine is opaque (as opposed to transparent) due to a precipitation in the wine. A synonym for haze is turbidity. Haze formation in wine has been discussed in e.g. "Enzymes in food processing" edited by T. Nagodawithana and G. Reed, 3rd edition, Academic press Inc., San Diego, Chapter 16, p.425, where it is described that grape proteins are held responsible for the formation of haze during the storage of wine. It is further believed that haze formation involves the reaction of proteins with tannins (polyphenols). Wines which are rich in tannins are more prone to develop haze than wines containing less tannins. Tannins are naturally present in the skin and seeds of grapes for red wines and, although to a lesser extent, also in the skin and seeds of grapes for white wines. Another source of tannins is the oak wood used for barrels, chips or staves, which are commonly added to wine to afford deeper taste. Formation of haze may occur immediately after separation of wine from solid residues, but may also occur at a much later stage. If precipitation is formed in wine after bottling, the wine becomes less attractive to the consumer, which will affect sales. Because of this potential to form haze, wines that form haze are known in the art as unstable wines. Haze formation is undesirable because the cloudiness caused by haze formation resembles cloudiness produced by microbial spoilage, which is undesirable.

A possible solution to prevent the formation of protein haze in wine is by adding mannoproteins. In WO96/13571A is described that yeast mannoproteins stabilise wine against the formation of tartrate crystals as well as against the formation of protein haze. Waters et al. (1994) Carbohydrate Polymers, 23, 185-191 , and Dupin et al. (2000) J. Agric. Food Chem. 48, 3098-3105, describe mannoproteins from Saccharomyces cerevisiae which protect wines from protein haze.

Surprisingly, we have found that gum prevents the formation of haze in wine.

Description of the invention

The present invention provides the use of a gum against haze in wine. The gum may be any gum. In a preferred embodiment the gum is a natural gum. In the context of the invention "natural gum" means that the gum is of natural origin, for example from animal, plant, or microbial origin. Examples of natural gums are gum Arabic, xanthan gum, agar gum, alginate, beta-glucan, carrageenan, chicle gum, dammar gum, gellan gum, glucomannan, guar gum, and locust bean gum. In a preferred embodiment the natural gum is gum Arabic.

It has been surprisingly found that a gum, when added to wine in an effective amount, may prevent, or retard the formation of haze and/or reduce haze. By prevention of the formation of haze is meant that adding a gum to wine may result in no haze. By retarding the formation of haze is meant that adding a gum to wine may result in a slower formation of haze, i.e. less haze formed per time unit, as compared to a wine to which no gum is added. By reduction of the formation of haze is meant that the final amount of haze in wine to which a gum has been added is less as compared to the amount of haze in a wine to which no a gum has been added. Of course, a combination of retardation and reduction also falls within the scope of the invention. The wine may be any wine. It may be a red wine, rose wine, or white wine. It may also be a dessert wine. The wine may be a non-stabilised wine or a stabilised wine. A stabilised wine is a wine which has undergone a chemical and/or physical treatment in order to prevent formation of potassium tartrate crystals or to prevent formation of haze, or both. For example, a stabilised wine may have been cold-stabilised, by which is meant cooling said wine to -4°C and subsequent removal by filtration or in elimination of the potassium and tartaric ions by electrodialysis or by the use of ion-exchange resins. A stabilised wine may also be a wine to which one or more wine stabilisers have been added in order to prevent the nucleation and/or the growth of KHT crystals. Examples of such additives are carboxymethyl cellulose, meta-tartaric acid, and mannoprotein.

The haze in the wine can be of any origin. For example, it may be a pectin haze, a starch haze, or a protein haze.

In a preferred embodiment the haze is a protein haze. Protein haze is a haze comprising protein. The protein which is comprised by the protein haze may be of any origin and type. The protein which may be a di-peptide, tri-peptide, smaller peptides (e.g. up to 50 amino acid residues), or larger peptides and proteins. There is no upper limit to the molecular weight of the protein. The protein which is comprised by the protein haze may consist entirely of amino acids, or it may comprise additional groups such as glycan and/or lipid moieties. Such proteins are sometimes called "glycoproteins" and "lipoproteins", respectively. The said additional groups are not necessarily covalenty bound to the protein moiety. The protein which is comprised by the protein haze may be natural protein from the grapes. It may also come from wine additives such as oak chips or staves, which are commonly added to wine to afford a deeper taste. The protein which is comprised by the protein haze may also come from wine yeast which has been added to the grape must. In a preferred embodiment the protein which is comprised by the protein haze is mannoprotein, more preferably mannoprotein which has been added to the wine or wine must, for example as a stabiliser. "Mannoprotein" is defined herein according to RESOLUTION OENO 26/2004 of the OIV (Organisation Internationale de Ia Vigne et du Vin) as a product which can be extracted from Saccharomyces cerevisiae cells and/or yeast cell walls by physico-chemical or enzymatic methods. Mannoproteins are different structures depending on their molecular weight, their degree and type of glycosylation and their load size. For example, the commercial mannoprotein Mannostab ^® is a 40 kDa glycosyl- phosphatidyl-inositol anchored mannoprotein (Product data sheet Mannostab ^® , Laffort, Bordeaux, France).

The gum may be added to the wine or must before or after filtration. It may be added to the wine or must as such, or in combination with other wine ingredients such as for example wine stabilisers. For example, it may be added to the wine or must together with mannoproteins.

The gum may be added to the wine at a final concentration between 1 mg - 40 g per litre wine. Preferably the gum is added to the wine at a concentration between 2 mg - 2O g per litre wine, more preferably between 5 mg - 10 g per litre wine, between 10 mg - 4 g per litre wine, between 25 mg - 1.6 g per litre wine, more preferably between 50 - 800 mg per litre wine, between 100 - 400 mg per litre wine, most preferably between 150 - 250 mg per litre wine.

In another aspect the invention provides a wine comprising a gum, said wine preferably further comprising mannoproteins. Said wine comprising a gum and preferably further comprising mannoproteins is characterized by a ΔNTU of at least 5, preferably at least 8, 10, 11 , 12, more preferably at least 14, 16, 18, most preferably at least 20, whereby the ΔNTU is expressed as the difference of NTU of a wine comprising a gum and a wine not comprising a gum, as measured according to the method of Example 1.

EXAMPLES

Materials and Methods

The amount of gum required to prevent, retard, or reduce the formation of haze depends on the stability of the wine, and is usually determined by applying the so-called

Proteotest (Vason, Verona, Italy) followed by nephelometry according to standard methods.

The Proteotest involves the addition of very reactive tannins to the wine. The amount of tannins in the Proteotest is unrealistically high: it is a forcing test, meant to ensure the formation of haze. The difference between the initial haze and the haze after addition of the tannin is a measure of the prepensity of the wine to forme haze: a larger delta NTU (NTUd) means a greater propensity to form haze, and therefore requirement of a larger amount of gum to be used in the wine. Example 1 Effect of mannoproteins and gum Arabic on the turbidity of a white wine This test was carried out to mimic the effect of mannoproteins and gum Arabic in extremely tannin-rich white wines. White wine (Soave) was split into four equal lots. The first lot (control) represents the wine without any additive. Lot 2 represents wine with the addition of mannoproteins (Claristar™, DSM Food Specialties, Delft, the Netherlands) in a concentration of 200 mg/l on a dry matter basis. Lot 3 represents the wine with the same mannoproteins as in lot 2, with additionally gum Arabic (Araban spray dry steril, Vason, Verona, Italy). Lot 4 represents the wine with the same mannoproteins as in lot 2, with additionally dextrorotatory Gum Arabic (Araban, from Vason, Verona, Italy). The concentration of mannoproteins was always 200 mg/l. The concentration of gum Arabic was always 200 mg/l on a dry matter basis. The initial turbidity of these wines measured in nephelometric turbidity units. Next, tannin (from the Proteotest, Vason, Verona, Italy) was added to lots 1-4, and the turbidity was measured again. The differences in turbidity (ΔNTU) are shown in Table 1.

I able 1

Lot Condition ΔNTU

1 Wine with no additives 10 5

2 Wine + 200 mg/l mannoproteins 33 4

3 Wine + 200 mg/l mannoproteins + 200 mg/l gum Arabic (L) 20 0

4 Wine + 200 mg/l mannoproteins + 200 mg/l gum Arabic (D) 16 3

The example clearly shows that the addition of mannoproteins to a Soave containing tannins gives rise to higher turbidity values and thus to haze, and that in the presence of gum Arabic the increase of the turbidity is significantly reduced.

Example 2 _{l C} N

The effect of mannoproteins and gum Arabic on the turbidity of white wine

This test was carried out to mimic the effect of mannoproteins and gum Arabic in extremely tannin-rich white wines. White wine (Chardonnay) was split into four equal lots. The first lot (control) represents the wine without any additive. Lot 2 represents wine with the addition of mannoproteins (Claristar™, DSM Food Specialties, Delft, the Netherlands) in a concentration of 200 mg/l on a dry matter basis. Lot 3 represents the wine with the same mannoproteins as in lot 2, with additionally gum Arabic (Araban spray dry steril, Vason, Verona, Italy). Lot 4 represents the wine with the same mannoproteins as in lot 2, with additionally dextrorotatory Gum Arabic (Araban, from Vason, Verona, Italy). The concentration of mannoproteins was always 200 mg/l. The concentration of gum Arabic was always 200 mg/l on a dry matter basis.

The initial turbidity of these wines measured in nephelometric turbidity units. Next, tannin (from the Proteotest, Vason, Verona, Italy) was added to lots 1-4, and the turbidity was measured again. The differences in turbidity (ΔNTU) are shown in Table 2.

Table

Lot Condition ΔNTU

1 Wine with no additives 17.2

2 Wine H H 200 mg/l mannoproteins 34.4

3 Wine H H 200 mg/l mannoproteins + 200 mg/l gum Arabic (L) 20.1

4 Wine H H 200 mg/l mannoproteins + 200 mg/l gum Arabic (D) 23.2

The example clearly shows that the addition of mannoprotein to a chardonnay containing tannins gives rise to higher turbidity values, and that in the presence of gum Arabic the increase of the turbidity is significantly reduced.

Example 3 The effect of mannoproteins and gum Arabic on the turbidity of red wine

This test was carried out to mimic the effect of mannoproteins and gum Arabic in extremely tannin-rich red wines. Red wine (Syrah) was split into four equal lots. The first lot (control) represents the wine without any additive. Lot 2 represents wine with the addition of mannoproteins (Claristar™, DSM Food Specialties, Delft, the Netherlands) in a concentration of 200 mg/l on a dry matter basis. Lot 3 represents the wine with the same mannoproteins as in lot 2, with additionally gum Arabic (Araban spray dry steril, Vason, Verona, Italy). Lot 4 represents the wine with the same mannoproteins as in lot 2, with additionally dextrorotatory Gum Arabic (Araban, from Vason, Verona, Italy). The concentration of mannoproteins was always 200 mg/l. The concentration of gum Arabic was always 200 mg/l on a dry matter basis.

The initial turbidity of these wines measured in nephelometric turbidity units. Next, tannin (from the Proteotest, Vason, Verona, Italy) was added to lots 1-4, and the turbidity was measured again. The differences in turbidity (ΔNTU) are shown in Table 3.

I able 3

Lot Condition ΔNTU

1 Wine with no additives 17.9

2 Wine H H 200 mg/l mannoproteins 32.5

3 Wine H H 200 mg/l mannoproteins + 200 mg/l gum Arabic (L) 1 1.5

4 Wine H H 200 mg/l mannoproteins + 200 mg/l gum Arabic (D) 12.1

The example clearly shows that the addition of mannoproteins to a syrah wine containing tannins gives rise to higher turbidity values, and that in the presence of gum Arabic the increase of the turbidity is significantly reduced.