The cork is drenched in tradition, too. At the high end of the wine trade, nothing will serve but cork off the tree. Forget about a twist oft-cap.
A company in Kent, Wash., hopes to change that attitude. The company, Supreme Corq, says it has something more reliable, a closure made of a proprietary blend of polymers.
Ana Hueto, a chemical engineer in product development at Supreme Corq, said that the product :s injection molded of a foamed material and has an eve:: cell structure. She said the manufactured closures are more consistent in performance than cork produced by the randomness of nature. The company is studying ways to otter closures specifically adapted to different types of wine.
Plastic closures of this type are being used to protect many commercial wines, but so far none of the company's products are used to bottle fine varietals.
One of the big questions about a closure, natural or not, is how much oxygen it lets seep into the bottle. Too much over time can cause wine to spoil.
To test its closures for permeability, Supreme Corq sends them to Impact Analytical in Midland, Mich. Rebecca Ortiz, manager of Impact Analytical's barrier properties laboratory, has designed a special setup to speed tests of artificial corks.
Her tests monitor the permeability of a closure until its oxygen transmission rate reaches a steady state. From start to finish, that takes 30 days or more.
She has eight Ox-Tran Model 2/21 testing machines, from Mocon in Minneapolis. According to Mocon, the system uses a coulometric sensor that is able to detect traces of oxygen down to parts per billion.
It is a chemical cell that generates an electrical current when it is exposed to oxygen. It uses a reaction that takes place between a cadmium anode and a graphite cathode.
A sample closure fits into a bottleneck that is then attached to a board. Ortiz said that tubing and Swagelok fittings allow inert gas to flush trapped air from the enclosed space and also take samples to the sensor.
Once in the bottle, only a small portion of the closure's surface remains exposed to the air. Before it enters the bottle, though, the artificial cork has been sitting in the atmosphere and is saturated with oxygen. It takes a few days for that oxygen to dissipate.
The Ox-Tran can switch back and forth between two gas streams, so it could take the eight machines more than a month to test 16 samples. To speed things up, Ortiz designed a setup in which there are two banks of 12 samples each. Now, one machine handles 24 samples.
When the samples are ready, Ortiz turns valves to connect one sample from each bank to the testing machine. They stay hooked up to the Ox-Tran all day long. The machine receives air samples from the first bank's sample for a while, then switches to the second bank. It repeats, bank A and then B again. After that, the ma chine resets itself.
The complete cycle repeats five times in 24 hours. Every day, Ortiz manually switches to the next set of samples, so each sample is tested every 12 days.
The manual switching was a matter of cost. So was building the tables in house. She put it up for proposals, but "the job bid was too high," she said.
The usual pattern for the tests is to start with high readings of oxygen that come down and eventually stabilize. How much oxygen finally gets through?
She said oxygen transfer is minimal, requiring the sensitivity of the Mocon device. Small wonder you have to let your cabernet breathe.
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|Date:||Nov 1, 2004|
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