PYRAZINE IN WINE
Experienced wine enthusiasts instantly recognise the smell and taste of sauvignon blanc through the presence of pyrazine. It is an important component of many fruits and vegetables.
There are three types of pyrazine:
Isobutylmethoxpyrazine
Isopropylmethoxpyrazine
Sec-butylmethoxpyrazine
The first is more prevalent in fresh bell pepper; the second in green asparagus or peas, and the third in beetroot.
Metoxypyrazines occur in grapes and contribute largely to the herbaceous and bell pepper characteristics, as well as the earthy aomes of some grape varieties, but mainly sauvignon blanc.
All pyrazines have very low sensory detection thresholds ( one to 2 ng/L in white wines and 10 – 15 ng/L in red wines ) thus minute quantities represent significant aromatic and flavour characteristics in wine. Surprisingly, while many wine enthusiasts find pyrazine in sauvignin blanc pleasant and appealing, in red wine they reject it. On occasion, merlot, cabernet sauvignon, and cabernet frans in cool vintages and regions contain high enough amounts of pyrazine to make the wine smell like a patch of vegetables.
Imagine one single grape in 500,000 metric tonnes of grapes changing the smell of the entire batch. This is the strength of pyrazine.
In Bordeaux, sauvignon blanc often if not always, is blended with Semillon ands muscadelle to overcome the aroma of pyrazine.
New Zealand’s Marlborough region, famous for its sauvignon blanc, usually uses exclusively the variety and quite successfully.
South African wineries sauvignon blanc are more aggressive both aromatically and in flavour, but perceived as pleasant by many consumers particularly when paired with buttery scallops, shrimps, and other seafood cooked in butter.,
California offers two versions of sauvignon blanc – fresh and barrel-aged. Those aged in barrel are called Fume Blanc, a take off of the famous Pouilly Fume in eastern Loire valley. California sauvignon blanc pyrazine levels are low, and those barrel-aged show even lower levels.
Chelamn sauvingon blanc can be quite free of pyrazine aromas, probably due to weather conditions and crop levels.
Ontario sauvingon blanc, much like its South African counterparts, display high levels of pyrazine and occasionally has and pleasant taste. Experience wine makers insist on super ripe sauvignon blanc, and vinify the lot accordingly to minimize the impact of pyrazine on the flavour.
Article contributed by Hrayr Berberoglu, a Professor Emeritus of Hospitality and Tourism Management specializing in Food and Beverage. Books by H. Berberoglu
|
