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Oak Barrel Alternatives in Winemaking
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No Wood No Good. Perhaps, but what type of wood are we talking about?
Ever noticed how oak barrels are always so conspicuous in cellar door outlets. Perhaps it's because barrels represent tradition, quality and patience in the eyes of the wine tasting public. Barrels are hand made by master craftsmen and women from a complex natural product using time-honoured methods. As such they represent a romantic ideal of wine culture.
But most of the wines that people consume in Australia have never seen an oak barrel. Cleverly worded marketing references to "oak flavour" and "oak character" on back labels seems to imply that they do. However, if the word "barrel" is not specifically mentioned on the label then chances are, the wine's oak character has been imparted using one of a myriad of non barrel oaking methods. These alternative methods include oak chips, oak powder, or by the insertion of oak staves into tank.
Before I go into detail as to how these non-barrel oak alternatives work, I must stress that there is nothing sinister or misleading about them. With the price of quality French (225 litre) barriques nudging $AUS1000, the cold hard economic facts are that you cannot age wine in them and sell it with a sub $AUS12 price tag. So for wines at this price point, a cheaper oak alternative is the only answer. As a comparison, oak character can be imparted using oak chips for only a few cents per bottle, compared with around $AUS3-4 if a French barrique is used.
The most common oak alternative is oak chips. They are added at various stages of the winemaking process, either thrown straight into the ferment or are later dipped into the wine tank after being placed into big "onion bags". Oak chips come in a variety of different types, varying in their forest of origin, in their size, the amount they are toasted, and whether they have been water pre-soaked. All these factors impact on wine character. Toasting chips gives them a smoky, bacon and caramel character. Due to their greater surface area, smaller chips give more character per unit weight added, and water pre-soaked chips are lower in astringent tannins. So for the winemaker there are lots of choices even with chips.
The use of oak powder is less common than chipping, although they are a very practical alternative if oak character is to be introduced during fermentation (a timing which many winemakers prefer as they feel that better oak integration is achieved if the character is introduced early). Recently I was fortunate to taste two versions of a despicably herbaceous Napa Merlot. One was unoaked and the other had been fermented in the presence of oak powder. To my surprise there was very little oak character present in the powdered wine, but even more surprisingly was a clear reduction in the level of the wine's herbaceousness. The improvement was not a figment of my imagination as I found out later that the amount of organosulfur compounds contained in the wine, (which contribute to its herbal character) was reduced by "powdering" the wine.
Wines can also gain oak character by inserting oak planks or staves into tank. Two variations of the method exist. Either longer planks are held vertically or shorter staves are stacked in a log cabin fashion at the bottom of the tank. These systems are cost effective and yield good results in terms of quality as the wine undergoes temperature controlled fermentation in tank in the presence of oak, achieving acceptable oak and fruit integration. The method is also practical as once sufficient oak character has been imparted, the planks can be lifted out, dried and used again.
So what's the catch? Most seasoned wine tasters would agree that wines aged in oak barrels are usually better than those which have had oak character imparted to them using alternatives. It is much harder to achieve seamless fruit and oak integration using alternative methods of oaking than with barrel. Chipping and powdering can also produce a brown paper bag like flavour due to extraction of the celluloses from the wood, whilst tank staves may produce more obvious bacon and smoky aromas. So why are barrels superior given that the wine is in contact with oak no matter what method is used? The answer lies in not so much in the chemical nature of the oak itself but in the fact that a barrel is unique in that it allows controlled amounts of oxygen in and out of the wine over a long period of time. Oxygen reacts with wine components, both modifying, and in most cases improving its flavour and mouth-feel. Alternative oaking methods are now being used in conjunction with a recently developed process called micro-oxygenation. Micro-ox is a high tech process of adding small, accurately measured amounts of oxygen to a wine over a period of time. The chips provide the oak flavour and the micro-ox process improves the mouth-feel. Scary eh …but if you want to continue drinking good quality sub $12 wine …..