The use of polyaspartates for white and red wine tartrate stability



By Karien O'Kennedy

The aim of the study was to compare the efficacy of various polyaspartates (PAs), including potassium polyasparate (KPA), with metatartaric acid (MTA) over time. The effects on wine colour stability, wine turbidity and wine filterability were also evaluated.

Project layout:
  • Trials were conducted on tank samples from tartrate unstable (but otherwise bottling ready) commercial wines.
  • Various different trials were conducted in different areas in Italy using different red and white wines.
  • All trials were performed in duplicate.
  • To monitor stability over time all controls and samples with the different PAs and MTA additions were stored at 20°C.
  • Cold tests at -4°C for 6 days were used to determine tartrate stability at three time intervals: immediately after addition, after six months and after 12 months.
  • For one white wine and one red wine pH and alcohol levels were adjusted to evaluate the stabilising efficacy of KPA at different pH (3.0 and 3.7) and alcohol (12% and 15%) values.

Main results:
  • Regardless of the different levels of tartrate instability, 10 g/hl KPA was able to stabilise all the wines tested. Wines remained stable even after one year – which was the duration of the trial.
  • All other PAs also stabilised the Dolcetto wine it was trialled on at a dosage of 10 g/hl. The wine was still stable after one year.
  • The adjustment of the pH and alcohol did affect instability levels, with higher pH and higher alcohol increasing instability. However 10 g/hl KPA was sufficient to stabilise the increase in instability.
  • The addition of KPA did not slow down the oxygen consumption rate of the white wines, even though KPA is known for chelating iron and copper.
  • The MTA treated wines became unstable after three months.
  • Both KPA and MTA did not affect wine filterability.
  • KPA treatments had no effect on wine turbidity.

Significance of the study:
This study demonstrated that KPA is a very efficient tartrate stabilising agent for both white and red wines and that it is more effective over the long term than MTA.

Reference:
Bosso, A., Motta, S., Panero, L., Petrozziello, M., Asproudi, A., Lopez, R., & Guaita, M. (2020). Use of polyaspartates for the tartaric stabilisation of white and red wines and side effects on wine characteristics. OENO One54(1), 15-26. https://doi.org/10.20870/oeno-one.2020.54.1.2527

Image: Shutterstock

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