The Effect of Nitrogen and Carbon Dioxide Treatment of Wines on Dissolved Oxygen Levels

Abstract

Oxygen levels of wines subjected to routine cellar processing were determined. The saturation level was found to be approximately 7 ml oxygen per liter. Wines being removed from cold stabilization treatment were found to contain oxygen levels approaching saturation. A single pass through a nitrogen stripping column reduced the level of high oxygen wines to approximately 2 ml oxygen per liter. A single pass through an in-line nitrogen sparger did not remove as much oxygen from high oxygen wines as did the stripping column but on low oxygen wines the two methods were about equally effective. A double pass through an in-line nitrogen sparger was an effective as a single pass through a stripping column in removing oxygen. The rate of nitrogen sparging, within the range of 1 to 3 liters of nitrogen per gallon had no differential effect on oxygen removal. The nitrogen sparger used was capable of treating 3,000 gallons per hour compared with a rate of 700 gallons per hour obtainable through the stripping column. Carbon dioxide was not as effective as nitrogen in removing oxygen and considerable absorption in the wine treated occurred. The greatest oxygen pickup in a bottling operation was found to occur as the wine was discharged into the filling machine bowl. No further increase occurred in the transfer to the bottle. Purging the air from bottles with carbon dioxide, prior to filling, was found to have no effect on oxygen level during bottling. The ability of a taste panel to differentiate between wines bottled at high and low oxygen levels was shown. Figures are presented to show that these new techniques involve nominal costs. It is felt that further studies and experience with oxygen removal techniques can lead to practices that should contribute significantly to quality maintenance and improvement in wines.