Light toast? Medium? Heavy? No it's not the waiter asking how well you'd like your raisin bread done, rather it's the current menu for winemakers buying new oak barrels. Coopers traditionally use fire to bend barrel staves to the correct curvature - during this process the staves can be charred to a light, medium or heavy toast at the customer's request. The degree of charring determines how smoky or toasty the wine will taste after barrel fermentation and/or maturation.

As well as contributing toast, wood tannins and obvious woodiness to wine, oak can provide more subtle elements. Of these the most readily identifiable are the flavours and aromas of vanilla and coconut. Vanillin is the compound found in wood that creates the familiar sweet fragrance of vanilla pods and vanilla essence. Another wood compound, lactone, is responsible for the coconut character more easily detected in American oak.

Oak barriques, 225 litre barrels favoured by makers of premium wines, also significantly influence the cost of finished wine. A new American barrique will cost the winemaker more than one dollar for each bottle of wine produced, a new French barrique will add more than three dollars per bottle. American oak has bigger and brasher flavour components than French and is therefore more likely to be used with big warm climate wine styles. In contrast, the restrained attributes of French oak are more likely to suit elegant and complex cool climate wines.

So oak barrels, which were once humble wine containers, have come to play an ever-increasing role in influencing wine flavour. Indeed one of my pet hates is that some modern wines, especially chardonnays, are so wood-influenced that consumers may sometimes wonder whether they are drinking oak essence instead of fermented grape juice. Luckily for oakophobes there is a definite trend to the production of unwooded chardonnays. Theoretically, these should be a dollar or three cheaper than their oaky siblings - but don't count on it

Tastings

Penfolds Adelaide Hills Semillon 1998 Delicate and medium-ripe nose shows light wood treatment and attractively perfumed varietal character. The softish palate is a precise balance of not overripe fruit, subtle French wood and mild acidity. A white at the elegant end of the flavour spectrum. Try with dips: taramasalata, tsatsiki, hummous. Rating: 87/100. Cellar: to 2005. Price: RRP $28. Discount: about $17.

Ninth Island Sauvignon Blanc 1999 Tasmanian white showing pleasing passionfruit aromatics. Dry and crisp in the mouth with plenty of sauvignon bite, especially in the middle palate. A refreshing style to serve as lunchtime aperitif. Rating: 86/100. Cellar: to 2001. Price: about $18.

Montrose Mudgee Barbera 1997 The barbera grape came to Mudgee from Italy's Piedmont region some 20 years ago, the immigration appears to have been a success. The colour is a lovely purple violet mix, the nose warm and savory. Soft and rich in the mouth it delivers lovely ripe fruit in the middle palate and a flavoursome, alcohol-laden (14 per cent) finish. Rating: 88/100. Cellar: to 2006. Price: about $20.

Redman Coonawarra Cabernet Sauvignon 1997 Attractive berries, smoky oak and faint almonds on the nose. Medium-weighted in the mouth with fine tannins, less of the berries, developed fruit and a tangy, very dry, firm finish. Try with a Sunday roast. Rating: 86/100. Cellar: to 2004. Price: about $20.

© Martin Field