The precise chemistry of wine production

Press, 17 August 1978, Page 14

The precise chemistry of wine production

Pasteur - thermovinification. Now there’s a term for you. It is the name given to the new method used by Cooks Wines to process the 1978 crop. As the name indicates, the process was discovered by Louis Pasteur and is similar to that used for pasteurising milk. After crushing, the juice and solids are separated in a giant separator called a centrifuge, passed through steam-heated pipes, held for a couple of minutes at controlled temperature, and then crash cooled. The yeast culture is then introduced and the juice passed on to cold fermentation.

So why all this carry-on when, until comparatively recently, the trick was to leap into a big tub of grapes, trample them around for a bit, and then run the juice off into a fermenting vat and let nature take its course? Well, there is a condition which affects grapes called botrytis cineria. On the Continent it is eagerly looked for and heralds a great vintage. The French call it “pourriture noble,” (literally noble rot), the German name is “edelfaule” and, although my Hungarian fails me, I am sure that the Greeks have a word for it. But the climate must be exactly right and, in New Zealand, that is exactly what it is not. In this country it goes the other way and produces an enzyme called laccase which causes the wine to oxidise more than somewhat. Oxidation will eventually impart a brownish colour to the .wine, cause it to lose its fruitiness and give it a “bitter edge.” So there we have the reason — pasteur thermovinification destroys laccase.

The opinion has been expressed that, as well as

destroying laccase, the method also destroys the elements which contribute to the gradual improvement of the wine in the bottle, but we will have to wait a few months to find out. Many other winemakers use sulphur dioxide to combat oxidation and Villa Maria have gone to great trouble to install a carbon dioxide line for the same purpose. All methods in the hands of a skilled winemaker appear to be quite successful. In any case, the first two whites off the line from Cooks are good. Fernhill, a back blended

riesling, is a very good example of the medium, fruity type but my’ personal preference is for the clean, • crisp finish of the Te Kauwhata riesling. Although Cooks won the race to market the first of the new season’s production, there is already a spate of 1978 whites available, and we are going to have to learn * spate of new names. The Rhine castles and flowery descriptions have, thank goodness, disappeared from the labels and have been replaced with place names, some of which, if you know your geography, will tell you where the grapes have been grown — a step in the right direction. Most of them are angled at the middle palate market, so let’s take the moselle styles first. I cannot say that any one is markedly better than an-

other. All are competently made and will provide enjoyable drinking. The planned change of name for the popular Montana Bernkaisler to suit the requirements for an export label has taken place. The new name is “Benmorven,” but don’t let that worry you. It is, if anything, a better wine and won a gold award at the ninth International Wine and Spirit- Competition held recently in the United Kingdom. Penfolds have jumped on to the bandwaggon with a good one in Woodhill riesling, as have Vidals with Mt Erin riesling, and Corbans Liebestraum has been much improved with slightly less residual sugar than the previous bottling. But the biggest surprise to me is a very palatable one from Glenvale in Esk Valley Muller Thurgau, a clean, well balanced back blended riesling. Previous attempts by this company to break into the table wine market have been far short of the standard. Maybe they are now on the way up. Three good whites, in addition to the Te Kauwhata riesling, for those who like them crisp and dry are Villa Maria riesling, Penfolds riesling and Villa Maria hock. For parties and barbecues three new carafe wines will also

be welcome — Cooks Estate Harvest White, a soft moselle style and Cooks Estate Harvest Red, a palatable medium red, both good quaffers, and Villa Maria Mountain Valley White for the drier palate. My one big criticism of the newly released whites is their lack of colour. They are all water white, obviously because of their extreme youth, and I do like to see at least a hint of colour. When I asked the marketing manager of a major wine company the reason for the indecent haste in getting them on to retail shelves, he replied with the wordless gesture of simply turning one hand palm up and rubbing the tips of his thumb and fingers together. Oh, well! I guess it’s a common complaint.

ON THE GRAPEVINE

By.

Maurice Hunter