March (No. 494)
Oxygen-permeable polyethylene vessels: a new approach to wine maturation
Anthony Flecknoe-Brown , Technical Director, Flextank Pty Ltd
It was previously thought that repeated opening and topping added most of the oxygen into an oak barrel for wine maturation (phenolic oxidation), but studies(1) have shown that the main source of oxygen comes from the continuous permeation (diffusion) of atmospheric oxygen through the barrel walls. Topping contributes less than 20%.
This has led to the development and adoption by larger wineries, of tank micro-oxygenation (MOX), wherein gaseous oxygen is directly injected into wine through a sinter. Tank MOX has mainly been used to reduce time to market for medium quality wines, by accelerating wine maturation rates beyond barrel “norms”. However, long, slow maturation in oak barrels for time periods based on the yearly vintage cycle, remains the method of choice for maturing premium wines.
In February 2004, Flextank Pty Ltd introduced a new type of wine-maturation vessel made from gas-permeable, high-density polyethylene. This internationally-patented system passively diffuses oxygen from the atmosphere into the wine in the same way as oak wine barrels.
In the 1000L size, the rate of wine maturation achieved closely matches that of the typical two to three-year-old barriques seen in most barrel rooms. This allows wineries to operate them together with oak barrels according to established cellaring practice, but with some notable cost and labour-saving exceptions.
NOTE: The complete article can be found in the March issue of The Australian & New Zealand Grapegrower & Winemaker.