WO2021009782A1

WO2021009782A1 - Use of poly-aspartate for the acid stabilisation of musts description

Info

Publication number: WO2021009782A1
Application number: PCT/IT2019/000055
Authority: WO
Inventors: Giovanni TRIULZI
Original assignee: Esseco S.R.L
Priority date: 2019-07-18
Filing date: 2019-07-18
Publication date: 2021-01-21

Abstract

The use of poly-aspartate (preferably of poly-aspartate of potassium) is disclosed for the stabilisation of musts acidity.

Description

USE OF POLY-ASPARTATE FOR THE ACID STABILISATION OF MUSTS

DESCRIPTION

FIELD OF THE INVENTION

This invention refers to the use of poly-aspartate (preferably of potassium poly- aspartate) , for the acidic stabilisation of musts.

BACKGROUND OF THE INVENTION

The production of wines, as widely known, entails the grapes juice fermentation (often derived from different several grapes mixtures, according to well-defined recipes) , commonly called must. Like every other fruit, the grape berry is composed of different substances with a different nature between them. Thus, there is a majority quantity of water, plus fructose, glucose (which are sugars required for the production of ethyl alcohol or ethanol through their fermentation) , and acids (especially tartaric, malic and citric) . Among the acids, the one present in the highest concentration is tartaric acid (quantity up to 12 g/1 of the must) . Moreover, it is possible to have additional substances, such as aromas, tannins, and others. The quantities of all these substances in the grape widely depend on its state of maturation: a more advanced maturation implies lower acidity, lower water content and higher sugar content .

Taking particularly into consideration, the acidity of the wine, it has an important influence on the taste perception, on the tartaric stability and the longevity of the wine produced. This factor demonstrates how it is important that the acidity grade of the must, has to be controlled appropriately and rigorously, to optimise these and eventually other parameters.

Examining more in detail the composition of the acid portion, it is observed that the acids, depending on the pH of the musts, can exist in a more or less dissociated form. The form that is not dissociated increases as the pH decreases.

As it has been mentioned, the tartaric acid is the acid with the highest concentration in the must. It is a dicarboxylic acid and it is the strongest of the organic acids restrained in the must, such that it mostly tends to exist in a dissociated form. The dissociated forms are two: the majoritarian requires the dissociation of a singular protonic group, while the other requires the dissociation of both protons. The hydrogenated form mostly seeks to join with potassium, while the completely dissociated form tends to bind with the alkaline-earth ions, in particular with calcium.

The salts that are formed (hydrogen tartrate of potassium and calcium tartrate) , normally turn out to be present in the must and consecutively into wine at concentrations higher than their solubility product, to form over- saturated solutions, in which the salts precipitate when the temperature decreases. Since the precipitates (if they would be present in the bottle) could cause commercial problems due to the refusal of the product by the customers, the lowering of temperature is used by wine producers to remove the precipitates themselves. This normally occurs in the same process of winemaking or, however, before the bottling of the wine produced.

Although the lowering of temperature effectively avoids the formation of precipitates in the product sold, it causes them to remove a significant quantity of tartaric acid (more often in the must) , which is first transformed into salt and then removed by precipitation and filtration. In this way, the acidity of the wine is altered. This results, of course, negative for the quality of the wine obtained.

To restore the correct acidity (at the end of all the procedures and before bottling) , it is used to add organic acids, such as lactic or malic, to solve the problem of tartaric acidity loss, to regain desirable organoleptic properties for the wine itself. However, this addition is not painless: it entails a non- negligible increase in production costs and it is possible to have (and generally there is) an imbalance of the overall organoleptic properties .

Other techniques have been developed to rectify the loss of acidity during the must to wine transition.

Some techniques have been developed (been denominated as a whole, as subtraction techniques) to enable the removal of cations in excess, to prevent the precipitation of poorely soluble salts. The two main methods related to this category are electrodialysis and cationic exchange resins treatment. In both cases, these are techniques widely known in this and other tech sectors which allow the reduction of the concentration of potassium and calcium cations below the solubility limits. The high cost of both installation and management features the disadvantage of these procedures. In particular, concerning the installation, large machines are required to be used, often not available nor reachable for small producers. On the other hand, management needs large quantities of water, which also entails the necessity to dispose of large quantities of liquid as wastewater. Finally, the cationic exchange resins require frequent regeneration treatments of the resins (usually with mineral acids) , once the saturation exceeds a determinate level .

Furthermore, among the processes for some organoleptic properties correction of musts and wines, there are additive techniques that enable the stabilisation of the must content during and after its transformation into wine. Yet, at the moment, none of these techniques are used to keep constant acidity.

BRIEF DESCRIPTION OF THE INVENTION

The problem at the base of the invention is to provide a practical way of preserving the acid properties of the must throughout and at the end of the winemaking, that could overcome the disadvantages mentioned above and which would allow to obtain high quality wines without the necessity of huge and expensive installations and without the need to artificially integrate the acidity of the must, preserving instead the one already present in nature. This purpose is achieved through the use of poly aspartate for the stabilisation of musts acidity. The sub-claims describe preferential features of the invention.

BEST WAY TO CARRY OUT THE INVENTION

As mentioned before, the present invention relates to the use of poly-aspartate acidity for the stabilisation of musts.

Generally, any type of poly-aspartic acid salt may serve to stabilise the acidity of the musts, by ensuring that acidity does not vary during the fermentation processes of the must for the production of wines; in such way, the organoleptic properties of the wines produced will be preserved and constant.

Poly-aspartic acid is a polymer of aspartic acid (COOHCH₃CHNH₂COOH) . Among its salts, the most preferred is poly aspartate of potassium.

The usage according to the present invention is implemented by adding a quantity of poly-aspartate to the must in its preparation phase or just before the beginning of the winemaking so that the acidity is preserved from the beginning and does not undergo alterations during the whole fermentation process.

Even without wishing to be bound to any theory, it is assumed that the poly-aspartate can join the species positively charged present in the must, preventing them from interacting with other substances, in particular with potassium and calcium ions. This matter prevents the precipitations of substances present in such proportion to exceed the saturation threshold and let the amount of acids (mostly tartaric acid) to remain constant. Then, in this way is not necessary to add an external acid. It should also to be observed that poly-aspartate generally has a cost far off lower than that of the acids that are normally added from the outside. Additions are even in a lower measure so that there is a distinct saving compared to what commonly occurs nowadays . It should also be considered that a special technical skill is not really required for the addition; small mistakes in the dosage have negligible effects; there are no contraindications of an environmental or sanitary nature; it does not require special equipment; and after all, the usage in accordance with the present invention is suitable for any kind of must.

Regarding the poly-aspartate additions to the must, there is not a particular limit. It is esteemed that they may vary from a minimum of 5 g / hi to a maximum of 100 g / hi (referring to the must) , preferably, from a minimum of 7 g/hl t a maximum of 70 g/hl referred to the must, an addition of about 10 g/hl is accounted as the best choice for a compromise between costs and benefits. The effects and results of the present invention are now clearly indicated, thanks to some applicable examples.

EXAMPLES EXAMPLE 1

A dose of 10 g/hl of potassium poly-aspartate was added to a sample of concentrated white grape Trebbiano must at 70 Brix. A concentrated must was chosen to emphasise the possible loss of acidity. The result is indicated in Table 1.

Table 1. Content of total acidity in the must

EXAMPLE 2

At the beginning of the alcoholic fermentation, a dose of 10 g/hl poly-aspartate of potassium was added to a sample of Grey Pinot must with a potential alcoholic volume of 11,6% and 3,5 pH. The quantity of tartaric acid present in such a product was checked in the final stage of the alcoholic fermentation; comparing the sample of the same wine obtained without additions.

The analytical data relating to the outlined test are indicated in the following table.

_ Ac. Tartaric D% Ac. Tartaric

Variety Sample Treated Tartaric

(g/i) versus witness

Witness 3,3

Pinot

grigio

KPA 10 g/hl 4,2 + 27,3

EXAMPLE 3

At the beginning of the alcoholic fermentation, a dose of 10 g/hl poly-aspartate of potassium was added to a sample of Riesling must with a potential alcoholic volume of 11,2% and 3,67 pH. The quantity of tartaric acid present in such a product was checked in the final stage of the alcoholic fermentation, comparing the sample of the same wine obtained without additions.

Ac .

D% Ac . Tartaric

Tartaric

Variety Sample Treated Tartaric

versus witness

(g/1)

Witness 2,3

Riesling

KPA 2,6 13

EXAMPLE 4

At the beginning of the alcoholic fermentation, a dose of 10 g/hl poly-aspartate of potassium was added to a sample of Verdelho must with a potential alcoholic volume of 13,4% and 3,47 pH. The quantity of tartaric acid present in such a product was checked in the final stage of the alcoholic fermentation comparing the sample of the same wine obtained without additions.

_ Ac . Tartaric D% Ac . Tartaric

Variety Sample Treated Tartaric

(g/hl) versus witness

Witness 2,2

Verdelho

KPA 2,5 13,6

EXAMPLE 5

Before the beginning of the second alcoholic fermentation, a dose of 10 g/hl poly-aspartate of potassium was added to a sample A of a basic Prosecco sparkling wine must with a potential alcoholic volume of 12% and 3,36 pH. At the end of the fermentation, it was left for 6 days at a temperature of -4 ° C. Instead, an amount rate of the same product (sample B) was subjected to cold treatment for 6 days at a temperature of -4° C before executing the second fermentation. The quantity of tartaric acid present at the end of the two processes described above was verified in both products. The analytical data relating to the outlined test are indicated in the following table.

Sample Ά Sample B

Tartaric acid (g/1) 6,05 5,20

REMARKS ON THE RESULTS OF EXAMPLES 1-6

All the tests described are proving the evidence that the addition of potassium poly-aspartate satisfactorily preserves the natural acidity of the must or wine samples (in which it was added) , making it a better alternative of the currently existing techniques .

EXAMPLE 7

The addition of the potassium poly-aspartate before the fermentation is also helpful to prevent the destabilisation of the color of red wines, for instance, caused by the reaction between anthocyanins and negatively charged colloids with limited solubility (for example portions of pectins) .

Such property depends on its high negative electrical charge, the pH of wine and its high hydrophilicity . Following these features, KPA interacts with free anthocyanins, creating negative colloidal complexes with high hydrophilicity, that consecutively remain in the solution and thus avoids color loss. This case is displayed by the data indicated in the two tables below.

The amount of hydrolysed pectins added in the tests reported in the two previous tables was equivalent to 100 ppm. The data indicate that KPA is able to limit the reduction of coloring intensity, that occurs after a cold test, due to the presence of hydrolysed pectins .

EXAMPLE 8

Many white wines typically contain protein compounds (in variable concentration as a function of climatic conditions of grape harvest) that are destabilised with time, giving rise to the formation of unpleasant turbidity. The phenomenon of protein destabilisation of wines depends on the superficial charge features, hydrophobicity and molecular mass of the proteins present . In many cases (where rapid turbidity progress occurred) , the aggregation of these compounds is caused by the presence of molecules with a high negative charge which operates as catalysts for this process (such as tannins for example) .

Even, the poly-aspartate of potassium can facilitate the destabilisation of such compounds, being endowed of a high negative charge. The aggregation of such proteins (stimulated by the poly-aspartate of potassium added before the fermentation) , allows their subsequent separation through the filtration process or centrifugation. Taking advantage of this process is then possible to reduce the dose of bentonite used to achieve total protein stability.

As evidence, the results of some experimental tests conducted are indicated in the table below.

The wine is considered stable from the protein viewpoint when it has a hot test <2 and a hot test with tannin <10.

The data reported above indicate that potassium poly- aspartate tends to substantially destabilise the proteins present in the treated wine, enabling the complete removal (reaching of stability) through the use of a lower dose of bentonite

EXAMPLE 9

Potassium poly-aspartate added before the fermentation can influence the potential redox of wine, tending to lower it. This property is important from an oenological point of view because it indicates that such consistency can limit the oxidative evolution of wines, prolonging their duration. Evidence of this property is indicated in the table below, which displays the values of the samples subjected to verification in millivolts.

However, the invention does not confine the particular arrangement indicated above, which constitutes only an exemplary embodiment thereof, but instead, provides possible variants (all within reach of a skilled person) ; and for this reason, does not necessary step out from the field of protection of the invention itself, as defined by the following claims.

Claims

1) The use of poly-aspartate for the stabilisation of must acidity.

2) The use as in claim 1) , characterised in that such poly- aspartate is poly-aspartate of potassium.

3) The use as in claim 1) or in claim 2) , characterised in that it is carried out adding a dose of poly-aspartate in the must during the preparation phase

4) The use as in claim 1) or in claim 2) , characterised in that is it is carried out adding a dose of poly-aspartate in the must, right before the beginning of winemaking.

5) The use as in any of the previous claims, characterised in that poly-aspartate in added from a minimum of 5 g/hl to a maximum of 100 g/hl (referred to the must) .

6) The use as in claim 5) , characterised in that poly aspartate in added from a minimum of 7 g/hl to a maximum of 70 g/hl (referred to the must) .

7) The use as in claim 5) and in claim 6), characterised by the addition of 10 g/hl.