Sara Cappelli, Valentina Canuti, Monica Picchi, Bruno Zanoni, Hend Letaief , Gianni Triulzi, and Paola Domizio*  
*Department of Agricultural, Food and Forestry Systems (GESAAF) University of Florence, Via Donizetti 6, 50144 Firenze, 50144, Italy (domizio@unifi.it)

The presence of potassium bitartrate (KHT) crystals in a wine bottle, even if harmless, is a cause of wine depreciation by some consumers. The addition of compounds that inhibit postbottling potassium bitartrate crystallization remains one of the most easily applied and inexpensive approaches for winemakers to employ. Subtractive methods like cold stabilization or electrodialysis have some disadvantages associated with cost, energy consumption, and selectivity. On the other hand, the stabilizing effect of common additives like metatartaric acid or carboxymethylcellulose can be time-limited and sometimes negatively impacts red wine color or becomes ineffective. These limitations highlighted the need for a new solution that guarantees long-term stability while preserving wine quality. Potassium polyaspartic acid (KPA), a new and recently approved additive (OIV/OENO 543-2016), is a synthetic polyamide synthesized by the thermal polymerization of L-aspartic acid. The stabilizing property of KPA against bitartrate was investigated with an emphasis on dosage and efficiency. A full-factorial design (23) was used to estimate the thermal stability of KPA over time. Its effect on tartrate and color stability was compared to that of other additives commonly used in the wine industry. In addition to strongly inhibiting potassium bitartrate precipitation, KPA does not affect color stability and can be added close to final filtration without modifying wine filterability. Moreover, KPA remained effective in wines even after exposure to temperatures between 30 and 40°C for an extended period, although there was a loss of protection in white wines kept at higher temperatures up to a maximum of 50°C. The impact of KPA on the sensory characteristic of each wine was also determined by sensory analysis. 

Funding Support: GESAAF – University of Florence Enartis-Esseco srl