9 September 2005: Spanish wine researchers put all their grapes in one pot

A young Spanish red-wine grape, Monastrell, will age better and keep its colour if mixed with more robust Merlot and Cabernet Sauvignon varieties, claim Spanish wine chemists.

Rosario Salinas at the Universidad Castilla-La Mancha in Jumilla, says that different grapes can bring out the best in each other with an unsophisticated co-winemaking technique. Different grape varieties are harvested and fermented together, according to the technique, even if some grapes are riper than others.

The abundance of anthocyanin - which gives fruit its colour - and other polyphenols characteristic of different grape varieties varies with age. Salinas said the co-winemaking technique got the most out of these molecules by encouraging co-pigmentation and anthocyanin polymerisation, processes that add to the colour of aging wines.

Salinas found that local Monastrell grapes, which have low polyphenol levels and don’t hold colour, aged better when combined with Merlot and Cabernet Sauvignon grapes, which have high phenolic content.

Co-winemaking is a primitive winemaking technique, says Paul Alsters, a wine expert who works for chemical company DSM, the Netherlands. This is because different grapes are picked and fermented at the same time, with some grapes being under ripe and some over ripe. The alternative mixed-grape winemaking process is the more sophisticated assemblage, favoured by Bordeaux producers, where each grape is harvested at its optimal ripeness and fermented individually, before being mixed.

’What Salinas has shown is that co-winemaking is not just bad, but that actually there might be advantageous effects resulting from synergy when fermenting everything together in one pot,’ said Alsters.

But not everyone agrees. While the concept of co-winemaking makes sense, said one  Australian wine researcher, Salinas’ work might not be the best illustration. The researcher  declined to comment further, saying that anything he could add would be ’unfavourable’. Katharine Sanderson