How technology is changing the future of wine-making
From Nasa's satellites to Napa's infra-red sensors, technology is changing wine-making - and fast. Jamie Goode raises a glass to the latest tricks
Wednesday 04 April 2007
Even within one vineyard, conditions vary. Traditionally, it would take viticulturalists decades of observation to work out how various patches of ground perform. Now there's a new practice that gives growers the benefit of a lifetime's experience in just a few hours. In California, for instance, the huge E&J Gallo and Mondavi wineries use Nasa technology. From satellites and small planes, pictures are taken using various spectra, such as infrared, which reveal exact conditions on the ground.
A tool adapted from the space programme, the Luminar 5030, a handheld spectrometer (above) - analyses the light coming from a grape - and is used to tell when the harvest is perfectly ripe. Coupled with GPS, the information produces a map of yields throughout a vineyard. Both approaches aim to quantify the variation in the vineyard, to identify bits that could be managed better.
What is it that makes some vineyards great? Scientists now think that many of the top sites allow a slow, steady supply of water to the vines which tails off as harvest approaches. In warm, dry wine-growing regions, irrigation is commonly used, and this allows growers to replicate the naturally occuring conditions of the world's great vineyards.
These techniques are known as regulated deficit irrigation (RDI), and partial root drying (PRD), but they need to be done with care: for best results, the vines need to be stressed, but not too much. A more sophisticated version of this manipulation involves installing two irrigation pipes either side of the vine row. One is switched on, the other switched off. Then the pattern is reversed after a week or two. This means that part of the root system is always stressed, and sends hormonal signals to the aerial part of the vine, which encourages it to invest its energy in fruit production. Yet the fact that the other half of the root system is well provided for avoids the grape quality being reduced by excessive water stress.
In recent years, a lot of attention has focused on organic and biodynamic viticulture, but there's a science-based method of environmentally friendly growing that is gaining ground. It's called integrated pest management, and it involves the use of technology to reduce the need for herbicides and pesticides.
Typically, weather stations in the vineyard feed data back to a computer that predicts when the risk of pests or diseases is highest. Chemicals are then sprayed on when needed.
Special predatory wasps or ladybirds are also used as biological control agents, to keep harmful insect numbers down, and the planting of different sorts of vegetation around vineyards to act as refuge for beneficial insects.
GENETICALLY MODIFIED YEAST
Many different strains of yeast exist, and they can all shape the characteristics of the wine they produce. Some winemakers prefer to ferment their wines with whatever yeast is hanging around the winery (called a "wild-yeast" or "natural" ferment), but many select cultured yeasts to give desired characteristics to their wines. Traditionalists don't like it, claiming that it is too manipulative.
In the past year, the first GM yeast strain has appeared on the market in California, made by First Venture Technologies. No one has owned up to using it yet; there's still a stigma attached. But could this be the future?
OXYGEN TO CONTROL TANNINS
Micro-oxygenation is a technique that introduces a controlled amount of oxygen at specific stages of the winemaking process. It was initially developed in the Madiran region of France to help with their typically tannic, unapproachable wines. Adding tiny bubbles of oxygen via a ceramic diffuser in a tank of just-fermented wine helps the tannins develop favourably. This technique gives winemakers an extra tool to help them shape their wines. Critics maintain that it relies on guesswork and good luck, and if it's used carelessly it can result in wines that taste excessively dry.
REPLACING OAK BARRELS
Barrels have been used for ageing wines for hundreds of years, and even the most modern of wineries will today usually have a cellar (or air-conditioned warehouse) full of them. Wine can pick up an oak flavour in them, particularly when the barrels are new, but they are expensive, hard to maintain, and require a lot of lugging around. So, winemakers have experimented with toasted oak chips. These are put in a bag and dunked in tanks full of wine, or else oak staves are bolted to the inside of tanks (below left). But barrels don't just add oak flavour: they also allow a small amount of oxygen to come into contact with the wine, so the more sophisticated approaches use micro-oxygenation, too. For cheap wines, these practices are common in many countries; so far not many winemakers are convinced it works for serious wines.
REDUCING ALCOHOL CONTENT
Alcohol levels in wine have been rising in recent years. Whether this is a style issue (because of grapes being picked riper to make sweeter wines), or a result of global warming, the wine industry is concerned.
However, techniques exist to remove alcohol from wine. One, reverse osmosis, is a filtration technique that takes out the alcohol from a portion of a particular wine, along with some of the water. Once the alcohol has then been removed from this mixture only the water remains, which can be added back to create a low-alcohol wine.
"Spinning cone" is a different method for achieving the same final goal. Some of the wine is put into a spinning cone that captures the delicate, volatile aroma compounds. These are then stored. The aroma-stripped wine is reprocessed to remove most of the alcohol. The de-alcoholised wine and the flavour are then blended with the bulk of the wine.It sounds horribly interventionist, but proponents say that the wines these techniques produce are often significantly better for having lost a degree or two of alcohol.
For hundreds of years, natural cork has been the one-size-fits-all solution for sealing wine bottles. But it is flawed: a small proportion of bottles - anything from 2 to 6 per cent, depending on who you talk to - end up "corked", with a musty taint caused by chemicals in the cork produced by the growth of microbes.
Now, there's a novel space-age technique to clean cork from taint by using what's known in the trade as "critical-point carbon dioxide". At a certain pressure and temperature, carbon dioxide is neither gas nor liquid: it enters a supercritical state when it has the penetration power of a gas and the cleaning power of a liquid. If cork is mashed up into small fragments, it can be cleaned of taint using this process, and then recombined with some synthetic microspheres and a food-grade glue to form a new sort of cork, called Diam, which is an interesting, environmentally friendly alternative to screwcaps and plastic corks, which were previously natural cork's biggest competitors.
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