Use of potassium polyaspartate for stabilization of potassium bitartrate in wines: influence on colloidal stability and interactions with other additives and enological practices

Use of potassium polyaspartate on white wines: interaction with proteins and aroma compounds

The precipitation of tartaric salts represents one of the main visual sensory faults of white wines. It can be prevented by cold stabilization or adding some adjuvants, such as potassium polyaspartate (KPA). KPA is a biopolymer that can limit the precipitation of tartaric salts linking the potassium cation, however, it could interact also with other compounds affecting wine quality. The present work aims to study the effect of potassium polyaspartate on proteins and aroma compounds of two white wines, at different storage temperatures (4 °C and 16 °C). The KPA addition showed positive effects on the quality of wines, with a significant decrease of unstable proteins (up to 92%), also related to better wine protein stability indices. A Logistic function well described the effect of KPA and storage temperature on protein concentration (R² > 0.93; NRMSD: 1.54-3.82%). Moreover, the KPA addition allowed the preservation of the aroma concentration and no adversely effects were pointed out. Alternatively to common enological adjuvants, KPA could be considered a multifunctional product against tartaric and protein instability of white wines, avoiding adverse effects on their aroma profile.

Comparison of the Electrodialysis Performance in Tartrate Stabilization of a Red Wine Using Aliphatic and Aromatic Commercial and Modified Ion-Exchange Membranes

The application of electrodialysis for tartrate stabilization and reagent-free acidity correction of wine and juices is attracting increasing interest. New aliphatic membranes CJMC-3 and CJMA-3 and aromatic membranes CSE and ASE were tested to determine their suitability for use in these electrodialysis processes and to evaluate the fouling of these membranes by wine components for a short (6-8 h) operating time. Using IR spectroscopy, optical indication and measurement of surface contact angles, the chemical composition of the studied membranes, as well as some details about their fouling by wine components, was clarified. The current-voltage charsacteristics, conductivity and water-splitting capacity of the membranes before and after electrodialysis were analyzed. We found that in the case of cation-exchange membranes, complexes of anthocyanins with metal ions penetrate into the bulk (CJMC-3) or are localized on the surface (CSE), depending on the degree of crosslinking of the polymer matrix. Adsorption of wine components by the surface of anion-exchange membranes CJMA-3 and ASE causes an increase in water splitting. Despite fouling under identical conditions of electrodialysis, membrane pair CJMC-3 and CJMA-3 provided 18 ± 1 tartrate recovery with 31 · 10^-3 energy consumption, whereas CSE and ASE provided 20 ± 1% tartrate recovery with an energy consumption of 28 · 10^-3 Wh, in addition to reducing the conductivity of wine by 20 ± 1%. The casting of aliphatic polyelectrolyte films on the surface of aromatic membranes reduces fouling with a relatively small increase in energy consumption and approximately the same degree of tartrate recovery compared to pristine CSE and ASE.

Adjuvants and additives for the colloidal stabilization of red wines without the use of cold

The presence of turbidity and precipitates in the bottle causes depreciation of wine by consumers. Colloidal instability is at the basis of these phenomena. The cold treatment is a technique widely used to stabilize wines, as regards both the tartaric and the colloidal precipitations. However, it is an energy-consuming technique. In view of a sustainable management of winery practices, the work aimed at evaluating the possibility of using some enological products for the colloidal stabilization of wines without cold treatment. 8 adjuvants (sodium and calcium bentonite, hot and cold soluble gelatin, chitosan, isinglass, PVI/PVP, carboxymethylcellulose) and 4 additives (kordofan gum, 2 different mannoproteins, a natural polysaccharide polymer) were compared. The trial was performed with a Barbera (2019) and a Montepulcianod'Abruzzo (2020) wines, stabilized against tartaric precipitations without cold, but with colloidal instability. Three days after the treatments the wines were racked, filtered (3 m) and bottled. After bottling and after 6 months of bottle aging, the wines were analyzed. Colloidal stability test (48 hours at 4°C) and shock test (1 and 7 days at 40 °C) were performed. As regards Barbera, the treatment with sodium bentonite (50 g/hL) or the addition of a mannoprotein (15 g/hL) allowed to stabilize the wine. For Montepulciano, having a higher colloidal instability than Barbera, the cold stabilization resulted necessary because no treatment was effective. All treatments had a modest impact on the color.

Impact of oenological processing aids and additives on the genetic traceability of 'Nebbiolo' wine produced with withered grapes

'Nebbiolo' is a well-known grapevine variety used to produce prestigious monovarietal Italian red wines. Genetic traceability is an important tool used to protect the authenticity of high-quality wines. SNP-based assays are an effective method to reach this aim in wines, but several issues have been reported for the authentication of commercial wines. In this study, the impact of the most common commercial additives and processing aids used in winemaking was analysed in 'Nebbiolo' wine using SNP-based traceability. Gelatine and bentonite had the strongest impact on the turbidity, colour and phenolic composition of wines and on residual grapevine DNA. The DNA reduction associated with the use of bentonite and gelatine (>99% compared to the untreated control) caused issues in the SNP-based assay, especially when the DNA concentration was below 0.5 pg/mL of wine. This study contributed to explaining the causes of the reduced varietal identification efficiency in commercial wines.

Stabilization of wines with polymers and new bio-based carbon materials

Wine is a complex product which changes its properties at every production stage, however due to the different processes which take place in the production stage can result into the formation of unwanted turbidity, deposition or can lead to distortion of taste. Despite the advances in improving wine stabilization processes, the search for new materials continues. The present work focuses on clarification of wines on the basis of new polymers and carbon materials obtained from bio-renewable raw materials and byproducts from the production of 2,5-hydroxymethylfurfural (5-HMF).

Evaluating Alternatives to Cold Stabilization in Wineries: The Use of Carboxymethyl Cellulose, Potassium Polyaspartate, Electrodialysis and Ion Exchange Resins

The tartaric stabilization of wines before bottling to avoid the precipitation of tartaric acid salts is an important and common step during wine production. The presence of precipitated salt crystals in bottled wines is detrimental to their quality and can even be a legal issue in some countries. Different methodologies are used in wineries to substitute the classical low-temperature stabilization process, which is an effective but costly process. This study comprises two years of experiments with red wines at an industrial scale. In the first year of the experiment, two subtractive methods (ionic exchange resins and electrodialysis) were tested, whereas two additive methods (potassium polyaspartate and carboxymethyl cellulose, both of them containing gum Arabic) were tested the second year. The tartaric stability of the wines, together with the oenological, chromatic and sensory characteristics, were followed during one year in the bottle. The results indicate that carboxymethyl cellulose and potassium polyaspartate (both combined with gum Arabic) were best at maintaining the sensory and chromatic characteristics during storage, with potassium polyaspartate providing a good tartaric stability to the treated wine and this wine being, in general, preferred in a sensory analysis test.