Spain's premier wine region, Rioja, has been in heated debate over the addition of new white grape varieties to those allowed under the Rioja denomination. The introduction of several almost extinct local varieties has been widely accepted but, writes Chris Losh, the addition of the ubiquitous Chardonnay and Sauvignon Blanc to the region's list of permitted white grapes has proved far more controversial.

About 18 months ago, something momentous happened in Rioja: the region's regulating wine council, the Consejo Regulador, voted to approve the planting of new white grape varieties.

These included some ancient, and almost extinct, indigenous grapes such as Turruntes, Maturana Blanca and Tempranillo Blanco, as well as Verdejo, a variety better known in Rueda, but reasonably successful internationally, and the indisputably international whites, Chardonnay and Sauvignon Blanc.

As yet, full approval has only been granted for the latter three by the Ministry of Agriculture, and the first plants will go into the ground soon.

Opinion both within the region and around the world has been divided over all this. Nobody has any real problem with the attempt to revive the near-dead local grape varieties. In fact, bar the odd 'we think this is generally laudable' statement, this worthy strategy for vinous resurrection has been largely passed over. But the same cannot be said of the decision to allow in the likes of Chardonnay and Sauvignon Blanc.

Even though the new grapes can never be more than 49% of the blend, it is an extraordinarily polarising issue, with bloggers, wineries and journalists falling into one of two camps: either 'Rioja is selling its soul to the devil and will be taken over by Constellation in 30 seconds', or 'what's the problem, Viura is rubbish anyway'.

Let's take the worries of the nay lobby first. Rioja currently has a vineyard area of 63,000 hectares, of which 59,000 are planted to red grapes. Even if half of the current white vines were pulled up and replaced with, say, Sauvignon Blanc, they would still make up only 3% of the total vineyard area, so the idea that the region has somehow diluted its image really doesn't hold water.

As for fears that the multinationals are hovering waiting to pounce, well, let's just say that Rioja isn't short of big companies; the arrival of Constellation would hardly make much difference. And in any case, the attractiveness of the region would surely be in its ability to knock out good volumes of consumer-friendly reds. Whether or not a producer also has a Chardonnay/Viura blend in its portfolio is hardly likely to be a deal-clincher. And with demand for reds outstripping supply, it is highly unlikely that growers will uproot red vines to replace them with white of any description.

So given all this, just why did the Riojans go to the effort of drafting the proposal and trying to push it through the various layers of national bureaucracy? Well because, as the aye lobby rightly point out, Viura really isn't an easy grape to get excited about. Sure, there is a niche market for the old, heavily oxidised versions, but marketing neutrality of flavour, even when barrel-fermented, is a tough sell.

"People are not paying that much attention to Viura," says one source in the region. "Rueda and Rias Baixas are taking over the Spanish white market; Rioja needed to increase its market share there."

The decision, in other words, was a business-driven one, namely: why bother trying to grow something that hardly anyone wants to drink?

The reason why the Chardonnay/Sauvignon versus Viura debate is such an either/or issue is that Rioja is fully planted, and it's almost impossible to increase the vineyard area. So a couple of thousand hectares of French grapes will inevitably come at the expense of local Spanish ones. It all comes down to whether you think it's worth making a stand on principle in defence of something as unlovable as Viura.

Where the situation becomes even more interesting is with regard to reds. Currently, red wine production means local Spanish varieties or nothing - basically Tempranillo, Garnacha, Graciano and Mazuelo. Companies which planted Cabernet 20 years ago as an officially-approved experiment are allowed to use it, but can't ever mention it.

That 1980s experiment broadly found what many people still think: that Rioja's wines are given some added class by a soupçon of Cabernet. Sadly, with the wineries broadly in favour and the growers broadly against, the grape has been stuck in limbo for two decades, with all votes on the matter being split evenly down the middle.

Interestingly, the initial proposal for opening up the white portfolio also included a plan finally to permit Cabernet Sauvignon in the reds. And while the growers tolerated the idea of revitalising the white vineyards, they once again drew the line at the idea of formally introducing Cabernet.

How, you might wonder, can there be grower-acceptance of Chardonnay and not Cabernet?

Well, it's a question of economics not ideology. Prices per kilo for Viura are dreadful because no-one wants to drink it. Chardonnay would be higher, so permitting it means potentially increased revenue for the growers.

But red grape prices are good in Rioja, and growers do not like the idea of being under pressure to uproot vineyards that are already earning them good money to replace them with a varietal that would probably not give a better return than Tempranillo or Graciano.

Not very high-minded, perhaps, but understandable. And worth remembering if the first taste of a Viura/Chardonnay in a few years time causes you to worry about the state of the region's soul…