CONTROL OF THE OXYGEN SUPPLY DURING THE CONDITIONING PART 1: PRINCIPLES AND WINE PREPARATION
VIDAL Jean Claude, MOUTOUNET Michel
The adaptation of methods for measuring dissolved oxygen in any type of container (thanks to the creation of gas tight circuits) and the continuous control of more than 14.000hl of still wine of all kinds during their conditioning (reception, treatment, bottling or bag in box packaging) have made it possible to characterize oxygen additions during the various operations which the wine undergoes and to propose solutions in order to reduce them, and to limit the use of antioxidants (SO2, ascorbic acid) while preserving the aromas as well as possible and by lengthening the shelf life of conditioned wines.
In general, the final total pick-up depends mostly on the relationship between the volume of wine to be treated and the volume of the circuit.
The most important enrichments occur particularly during the operations of cold tartaric stabilisation and during the bottling, especially if no precautions are taken to protect the wine from the oxygen in the ambient air.
As for the oxygen trapped during conditioning in the headspace, the tests carried out show that the quantity of oxygen trapped in the headspace right after stoppering varies from 0.38 to 3.58 mg per bottle, to which it is necessary to add the dissolved oxygen in the wine whose measured values vary from 0.5 to 6 mg/L.
The rationalization of the operating conditions, the judicious use of neutral gases especially at the beginning and the end of operations, as well as the inertion of bottles before filling and right before closing make it now possible to control and significantly decrease the oxygen pick up during all the operations related to conditioning. The objective is to go below one milligram of total oxygen trapped in bottle or bag in box has already been reached in certain installations.
Finally, the conditioners will continue to have more possibilities to put in practice a qualitative evolution of the desired wine and this also for the closures, which have had significant progress in their homogeneity and their oxygen permeability levels (Oxygen Transfert Rate).
Published on 28/10/2008
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