Up until recently, racking has been seen as the least interesting component of our Rent-a-Row winemaking process. Racking is the stage in the winemaking process where the wine is transferred from one demijohn to another, leaving the lees (a slurry of dead yeast and sediment) behind. In addition to removing the bright purple sludge from their Shiraz, our Rent-A-Row winemakers use this time to add oak to their wine. Perhaps the stage isn’t as interesting, or perhaps it’s just the middle of winter, it’s cold, and it seems a hell of a lot less exciting than romantic sunny days out in the vineyard, picking grapes and stomping them with your feet.
Well, that was until we posted to Instagram about how our racking weekends have been going and how important and individual the oak additions can be. Since that post we have been getting countless emails asking us about the importance of oak, the differences between oaks and the significance of adding oak to wine. After finding very little on the subject, especially on the difference between the two main types of oak – American and French oak – we thought we’d shed some light on the subject.
The relationship between oak and wine dates back to the Roman Empire. Before the use of barrels, clay amphorae were used by the Greeks and Romans to store and transport wine. These vessels were airtight, but impractical due to their weight. Oak wood was abundant in European forests and was flexible enough to craft into barrels. Waterproof, lighter and more durable than clay, oak barrels have been used for wine storage for centuries. 
It wasn’t until the 1800’s that people began to develop an understanding that the oak wine was stored within added certain flavour characters to the wine as well as depth and interest to the nose. 
In the modern day wine industry, wine is less frequently stored in oak barrels. Barrels are expensive, difficult to clean, annoying to store and often good only for furniture after a few vintages. Instead, oak barrels have been swapped out for stainless steel vats and drums.
But just as those in the 1800’s could appreciate the subtle and smooth complexities of flavour that the oak barrels attributed to their wine, modern day winemakers still rely on oak to get the sophisticated, deep flavours and fragrance characters in their wine. So how do most modern-day winemakers get oak character into their wine without the use of wine barrels?
Instead of adding their wine to oak, they add oak to their wine. This oak comes in many forms and the size used can be scaled up or down to the size of tank you use and how long you plan to mature the wine. Oak can be in the form of large planks – staves – or they can be much smaller – oak chips. The size (and surface area) of the oak dramatically affects the maturation (or release time) of the oak. Oak powders have immediate impact, but a short life time for cellaring, whereas chips and staves require a few months contact time and will benefit from age.
Going back to Rent-A-Row Racking, we need to use a small size of oak, something that fits in our demijohns and that can mature within 2-3 months. Last year we used a product cut into the shape of dowels, which worked well but caused problems with bottling (they were the same size as the hoses). This year, we’ve gone down the more traditional path of using oak chips.
Reminiscent of the bark chips that would end up in your shoes after a good run around in the playground at lunch time, it’s hard to believe that these babies could be associated with something as sophisticated and swanky as the premium wines you bring out at dinner parties. But you see, it’s what they are made of, where they come from, and how much or little you use that impacts on the individuality of each wine.
French vs American oak is the dichotomy discussed here. There are of course other types of oak on the market, but these are the two most commonly used in red wines.
Being a French varietal, Shiraz, with an alternative name in Syrah, is most commonly matured with French Oak. French oak is the subtler of the two, adding length to the palate and allowing the beautiful shiraz fruit tannins to shine through. French oak is often described as silky, smooth, and subtle with notes of vanilla, spice, and jasmine. It adds aroma to wines and spice to the back of the palate, with minimal impact on the front & mid palate.
American oak by comparison is obvious or unsubtle, at least to the French. It is bolder in flavour, aroma and contributes to the front-mid palate and provides a sensory sweetness to wines. It’s flavours border on that of caramel – I describe it as biscuity – with a vanilla sweetness at the mid palate. It is commonly used in lighter reds and is a staple of Spanish wines such as those originating from Rioja –Tempranillo and Grenache. And of course, American wines such as those from Napa & Sonoma. 
It seems surprising that the Spanish wines are characterised by American Oak – oak from across the world – rather than the oak of their French neighbours. French barrels were harder to come by and much more expensive. Whereas, due to the opening up of trade between Spain and independent American colonies, American oak was abundant and cheap. As a result, the sweet vanilla character of American oak is now a hallmark quality central to the identity of Spanish-style wines. (We released some last month!)
When we take our customers through this process, we put them through some rigorous tastings of wines (hard work, right?). We expect that our customers know, instinctively, what they like in relation to wine and oak. But expressing that in terms of French or American and how much, is a different beast and our wine tastings help to provide context. Using adjunct oak gives a winemaker a lot of control – they can add a little or a lot of oak and of all different types.
We taste Shiraz with 100% French Oak, 100% American Oak and everything in between to determine what type and ratio of oak they like. We then taste wines with the same oak added, but at different levels of addition – expressed as grams per litre – to determine how much oak to add. More oak will add length and body to the wine, but make the wine less fruit forward. Less oak will maintain the core fruit flavours, but with less length and less cellaring potential. The aim here is for balance – but balance is relative to the individual.
What’s enjoyable for us at this stage is that we have provided the same tasting and discussion to over 100 groups of winemakers – each deciding on an oak blend and level of addition to add to their wine. A true testament to the subjectivity of taste. It’s great to see both new and past Rent-A-Row winemakers being engaged in a stage that they’d otherwise missed, walking away after a fun session in the winery and with a lot more knowledge about what makes great wine. With so many different Rent-A-Row Shiraz wines in the works this year, we look forward to bottling (and sampling!) everyone’s unique batch in the Spring.