5.5.2.e Oxygen intake caused by wine operations during the ageing process

During the ageing process, the wine is exposed to various operations, starting with barrelling and ending with preparation prior to bottling. From a quantitative point of view, oxygen additions to the wine caused by handling constitute the majority fraction during ageing.
During these operations, the wine comes into contact with air and therefore with oxygen. The exposure is different depending on practices and procedures. The following table summarizes the different practices during the ageing process and their average theoretical contribution if no precautions are taken regarding oxygen.

The following values are given for a temperature of 15°C and at atmospheric pressure. It is clear that for a given wine, the operations carried out are not insignificant with regard to oxygen dissolution.
However, it is quite possible to modify the practices to reduce the quantity of oxygen added to the wine.

The results of a barrel-to-barrel racking by candlelight or a racking tube are quite similar. Using a racking tube reduces the dissolved oxygen. The quantity falls from a theoretical 3 to 5 mg/L to about 1 mg/L. The oxygen input is mainly due to the final collection container which is open to the air.
These results show that it is possible to decrease the amount of oxygen by a factor of 4 during this practice. Depending on the wine's requirements, it is then possible to choose the technique to use during ageing.

When pumping barrels into vats, it is possible to inert the hoses and/or the vat. Pumping from the bottom or from the top is also possible. Each method results in different amounts of oxygen being introduced. Knowing this information is therefore useful in order to adapt to the wine's oxygen requirements.

This data is derived from measurements taken at Château Latour. We can see that the difference is quite significant here too. The pumping methods are easily controllable.
A high flow rate leads to a greater dissolution of oxygen (case 2) but with total inerting the value remains quite reasonable (case 1), approximately 1 mg/L compared to 2 mg/L theoretical.
In the best case (3), the oxygen is four times lower than the theoretical quantity.