mdcc (2010-09-22)
W temacie korków i zakrętek - ciekawe teksty od człowieka pracującego dla wytwórni zakrętek. Pytanie brzmiało - jaki jest optymalny poziom oddychania butelki (w nawiązaniu do dyskusji że zamknięcie szczelne nie jest dobre, nieszczelne również) : The short answer: There is no single "optimum" amount of oxygen - variances in wine style, variety, vintage etc are too broad. Instead, we have specced the range of oxygen rates that winemakers might want and give them the choice. On a wine-by-wine basis, only the winemaker can make that selection - and I wouldnt want it any other way. The long answer: If you look at post-bottling oxidation from the more pragmatic stance of SO2 management, then the range of oxygen rates can be determined: 1) We know that the average bottling SO2 level of a wine is 30ppm. (this is from my 12+ years in the CA wine industry) 2) We know that in model wine studies 1ppm of oxygen can lower your free SO2 by as much as 4ppm 3) We know that a wine will allow acetaldehyde to survive in equilibrium somewhere around 10ppm free SO2. 4) We consider that the ability to smell a wine as oxidized (aldehydic) is the official end-of-life for the wine. So by logic, we can say that you can allow 5ppm of oxygen into a wine, but after that, it's life is dependent on the wine's own ability to absorb oxygen. Heavier wines will absorb more, lighter wines less. Given that wines are not expected to be "perishable" (they dont have expiration dates) we feel that at the very least the consumer has the right to safely hold on to a wine for 5 years and in fact see an increase in quality over that time. So 5ppm over 5 years = 1ppm O2 per year. On the other side of the equation with concern to reduction, the tin screwcaps let that same 5ppm in over the course of 150+ years. The Saran screwcaps are surprisingly inconsistant, but range on the order of 40 to 80 years for that same 5ppm. Given these observations the relevant range is easy to define: Certainly nobody is going to complain if a wine lasts "only" 10 years. And in fact, the wines most likely to be put down deliberatley for this purpose are those that are the most tolerant of oxygen exposure. So we have targeted the range of 1/2 to 1 PPM of oxygen per year. Heavier wines with a 5 year closure will probably age for 10-20 years gracefully and with no ill-effect, and lighter white wines can select a 10 year closure that will let them age gracefully without overdoing it. That said, if winemakers want more or less than this range, we will give them that! I hope that was complete information overkill... _________________ Tim Keller www.vinperfect.com
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