Accuro for ORP
Oxidation Reduction Potential "ORP" is a measure of the tendency of a molecule to acquire or lose electrons and thereby be reduced or oxidized (definition adapted from Wikipedia). Roger Boulton at UC Davis has advocated for a long time to measure the ORP in wine fermentations to understand the fermentation kinetics better. However, academic research and adoption of its use in the wine industry have taken off only recently.
We measure ORP with an electromechanical probe suspended in the fermenting must (not the cap). Many wineries in the US seem to use Hamilton probes with some oxygen management controller (e.g., FloTek, see https://flotekca.com/redox-fermentation-control-for-wine-industry). We found a more economical solution from Accuro (aka WineGrenade), a startup in New Zealand. The probe connects to a communications unit that transmits measured data to the cloud, from where it can be inspected/downloaded through an open-source data visualization tool (www.Grafana.net). The picture on the right shows the sieve from the fermentation tank, post-fermentation, with the probe hanging inside. The image on the left shows the control unit.
We record the ORP measurement once a day, right before and right after each punchdown in our database. The measurement before punchdown should be significantly lower than the measurement after. The increase is a result of oxygen added during the punchdown. A general rule is that the ORP should not drop below -70mV. However, we have observed fermentations that completed successfully while the ORP dropped below 110 mV. We have yet to figure out how to interpret the data. We aim to improve the timing and amount of oxygen injections.
The following screenshot shows the recorded measurements on the left and a picture of the Grafana screen on the right.
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Last updated: March 4, 2023