Wine and screw caps
I am asked frequently about screw caps on wine. The main reason for their introduction initially was to prevent the musty flavour that occurs in about 3% - 5% of corks. The musty flavour is caused by an invisible mould and the wine is said to be corked a term that is confused with other cork problems such as broken and crumbling corks (the latter are physical problems but do not affect the wine flavour). However new reasons for screw caps (often known by the most common proprietary name, Stelvin) have emerged. Even though a cork may not have the invisible mould that causes mustiness, there are other problems with corks. They are inconsistent some seal a bottle well and others not so well. Tiny traces of oxygen can leak in to a bottle through a slightly more porous cork. Over long periods of ageing bottles of wine, individual bottles taste differently to each other some bad, some not so good, and some are great. Greater ingress of oxygen causes a wine to age faster. Screw caps offer a closure that delivers a consistent taste across all bottles.
The cork industry and supporters have fought back with some quasi science to suggest that ingress of tiny traces of oxygen while a wine is ageing, is vital to wine developing. The latest research (by researcher Allen Hart at large Australian producer Southcorp) concludes that oxygen is not required and wines will age properly when sealed with a screw cap.
Practical advantages of screw caps include the easy ability to open the bottle, and the elimination of the requirement of storing wine bottles lying on their side. You can store screw capped bottles standing up.
There are still some small issues with screw cap technology (such as for sparkling or slightly fizzy wine) but it wont be long before most wines, white or red, are sealed with a screw cap!
For the latest (and admittedly very technical) information on screw caps, see the book published in June 2005, Taming the Screw by Tyson Stelzer (see www.winepress.com.au).