THE EFFECTS OF BARREL FERMENTATION AND BARREL AGING
“Oak is a condiment not a nutrient. People who think of oak as a primary flavour in wine also tend to think of ketchup as a vegetable.” Randall Grahm, owner and winemaker of Bonny Doon Winery, California
Winemakers of yore stumbled over the benefits of fermentation and aging centuries ago. Ever since, techniques have been invented to refine the process.
First, the quality of wood was examined. Through taste, wine connoisseurs discovered that quercus robur, European oak, yielded texturally more refined and smooth wines. The search led them to a few forests in France which have since acquired world wide fame.
They are: Limousine, Troncais, Nevers, Allier, Jupille. The first two impart an overwhelming vanilla flavour to wines and are mostly used by cognac manufacturers. White wines may be fermented in barrels to extract tannins in an attempt to render the end product cellar worthy. Most white wine is not meant to benefit from barrel fermentation and/or aging.
Barrel agingbenefits red wines more than white wines and most winemakers use this technique for their better quality products like Cabernet Sauvignon, Meritage, Chianti Classico, Brunello di Montalcino, Bordeaux blends, Shiraz and blends thereof , Rioja wines and Ribera del Duero.
Light wine grapes like Gamay for Beaujolais are often not barrel-aged.
During aging three processes take place; controlled slow oxidation, imparting tannins, and texturally smoothing the wine.
It seems that French oak (Allier, Nevers, Jupille) is tight grained, impart a fine texture to the wine, and changes the flavour favourably through slow oxidation.
French harvest old trees (over 100 years old and with north exposure), hand-split, and “season” for a minimum of two years before construction the barrel, and toast according to specification (light, medium high toast). The size of the barrel affects the texture – 225 – 250 litre casks seem to be best for Bordeaux blends, Pinot Noir and Chardonnay.
Other European countries (Slovenia, Hungary, Romania, Russia) produce oak and export for barrel making. Hungarian and Russian oak yield good results, but they are inconsistent in quality. Italian winemakers prefer Slovenian oak.
Some barrel manufacturers now incorporate staves from different countries in one barrel and the results are reportedly satisfactory.
In the USA, the white oak (querqus alba) is abundant and used in barrel manufacturing. Barrel makers, however, have been building them for whiskey aging and lack the expertise in manufacture of wine barrel. Some French barrel makers set up shop in the USA and use America white oak. Over the past 30 years, American oak aged wines tasted show a coarse texture and penetrating vanilla flavours. White oak has a coarse grain and oxidizes wine faster. For these reasons high-quality winemakers use exclusively French oak. Some blend French and American oak wines for their medium priced wines. Low-end wines are usually American oak aged, some just flavoured with oak chips.
The difference is cost and results. American oak barrels cost approximately
$ 300. – 350.- less than French. In view of the fact that a barrel can be used twice only , the additional cost per bottle is significant.
Rebuilt barrels are never use by winemakers who care about quality.
Two enterprising Canadians scientist have recently started marketing Ontario oak barrels harvested from forests around Brantford. The wood is hand-split and shipped to the USA for construction. These barrels are now used by Lailey Winery regularly, and many others on an experimental basis. So far, results are encouraging.
Ontario white oak is tighter grained than US and has less vanilla. One can say that Canadian oak is somewhere between French and American oak.
It is less expensive than French barrels, but more than American products due to transportation costs.
Oak flavours in wine must never overwhelming and organoleptically noticeable. It is much like cooking with spices and herbs. They should carry only a supporting role and never dominate. Steeping oak shavings in wines produces inexpensive wines. Some winemakers shoot oak chips from one end of a stainless steel container to the other to impart oak flavours quickly with predictably poor results.
North Italian winemakers use mostly upright Slovenian oak vats with 9000 – 10,000 litre capacity. Sometimes chestnuts barrels are used.
These huge vats have a crust of wine tartars on their walls and which actually block air penetration, thus oxidation is minimal.
Modern winemakers use French, mostly Allier, oak barrels with laudable results.
German winemakers like to preserve fruitiness and shy away from barrel aging in most instances. If they do use barrels, they are huge, some are 60,000 in capacity and made of extra-hard German oak which is so tight as to hermetically block air from entering.
Barrel aging requires judicious control and strict supervision to obtain best results.
The length of aging depends very much on the results desired. One to one-and-a-half are most appropriate to preserve fruitiness and influence both flavour and texture favourably.
Ontario oak has a god future only, if costs can be reduces by assembling barrels here, which in turn depends on volume. I hope that wineries collectively will decide to use Ontario oak barrels thus facilitating the opening of a barrel manufacturing in the country. The number of wineries in Ontario and British Columbia are sufficient for a small facility to be profitable.
Article contributed by Hrayr Berberoglu, a Professor Emeritus of Hospitality and Tourism Management specializing in Food and Beverage. Books by H. Berberoglu