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lundi, 04 janvier 2016

CLIMATIC CHANGE AND WINE (PART 3 OF 3)

CLIMATIC CHANGES: TOWARDS MORE MANIPULATIONS IN THE VINEYARD AND THE CELLAR


Claude Gilois

 

CREATING VARIETIES MORE RESITANT TO DROUGHT AND HEAT

 There are three methods for achieving this: Hybridization, Genetically Modified Organisms and Marker Assisted Selection.

 

 Hybridization

This is the oldest method and the one that has been used since agriculture was born to improve quality and quantity. Crossing various plants results in crossing the genetic make up and improves their resistance and adaptability to their environment.

Hybridization played a major role in improving plant diversity and resistance before phylloxera devastated vineyards, but since then, hybridization has been confined mainly to research institutes, much of which is indebted to Alain Bouquet of the French INRA (Institut National de la Recherche Agronomique). In 1974 he initiated a program and started crossing vitis vinifera plants with muscadinia rotondifolia, an American vitis that possesses genes resistant to phylloxera, mildew, odium and to a small worm (nematodes) responsible for many vine diseases.

 

From his first crossing, he subsequently crossed known vitis vinifera cultivars such as merlot, cabernet, grenache and the newly created varieties that kept the resistance conferred by the muscadinia rotondifolia. However, the INRA did not authorize these to be used as new cultivars (apart from experimental trials) arguing that they only possessed a monogenetic resistance (only one gene is resistant) which could be overcome by pests and preferred to wait to develop polygenetic plants (several genes of resistance) to ensure that they would be more resistant to pest infestations. This decision was not consensual in the profession and generated criticism from eminent university professors and various viticultural authorities. 

Today, the INRA has developed six grape varieties (five reds and one white) by hybridization, which exhibit polygenic resistance to pest infestation, and experimental trials are currently being carried out in four different locations in France. If the results are conclusive the new varieties could be authorized in 2016. It usually requires 20-25 years to develop a new variety that is agronomically interesting and shows interesting organoleptic qualities. 

 

Paradoxically, the use of new resistant cultivars is more developed in some countries such as Switzerland and Germany. Switzerland, a small grape growing country of great diversity (more than 60 different cultivars) has successfully introduced a hybrid cultivar, Gamaret, obtained by crossing the vitis viniferas plant with vitis amurensis from Asian origins. This new grape variety is, today, the most widely planted variety in Switzerland. Three additional grape varieties have since been successfully created, solaris, souvignier gris and muscaris.

 

The German Frieburg Institute has also been very active in this area of research and seven new white varieties as well as seven red varieties have been created with suggestive names such as Cabernet Cortis, Cabernet Carol, Cabernet Carbon, Prior, Monarch and Baron. They are now listed or will be listed in the catalogue of approved cultivars for quality wine production.

Altogether, in the world today, more than 3000 hectares of these new varieties are being cultivated in 25 different countries in the European Union and also in South Africa, Chile, Australia and New Zealand etc[i].   In Europe they are all classified as AOP (Appellation d’Origine Protégée) and as Vitis vinifera on the basis of the morphological characteristics. 

 

It is probably worth mentioning that these cultivars are new and that hybridization techniques involve the transformation of a known cultivar into a different one. This is, of course, problematic when it comes to worldwide known varieties that have contributed to the reputation of regions such as Bordeaux, Burgundy plus some other prestigious regions.

 

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Genetically modified organisms (GMO)

 

A genetically modified organism is an organism whose genetic materiel has been modified by human intervention. It is worth noting that the American definition is much more vague and it includes modifications that occur naturally or artificially. The technique involves inserting a small fraction of the DNA of a micro-organism (usually, but not always, a bacteria or a virus) called a transgene into another living organism to modify its genetic characteristics.  So far, for vines, research has essentially resulted in making the plant more resistant.  This type of technology applied to vines came to the fore when an experimental GMO vineyard, set up by the INRA of Colmar to test the resistance of genetically modified vines to fanleaf virus, but was destroyed by an anti-GMO activist as indeed were most of GMO cultures in France.   Interestingly enough, a few days before the vineyard was destroyed, the court of Strasbourg cancelled the authorization of the culture of the experimental vineyard given by the French Ministry of Agriculture, as it did not conform to the European directive 2001/18 that regulates the usage of GMO.

 

This begs the question as to why such potentially useful technology is facing such huge resistance. The history of its development will cast some light on the subject. 

 

In 1972 the first experiment of transferring genetic material from one organism to another took place. Confronted with such a powerful technique, the scientists decided to put a moratorium on it, a moratorium that would only be lifted in 1977. In 1980, the Supreme Court of the United States authorized the patentability of living matter, providing it was truly “man-made” (judgement confirmed in 1987). In 1992 the European Union also permitted the principle of patentability of living organisms. In 1998 the Organization for Economic Co-operation and Development, OECD, established the principle of ‘substantial equivalence’ stipulating that if a new food or food component was found to be substantially equivalent to an existing food or food component, it could be treated in the same manner with respect to safety. This exempted all genetically modified organisms from toxicity tests and any labeling regulations.  As soon as genetic engineering was perceived as a huge potential market worth hundreds of billions of dollars, scientific and ethnic norms were replaced by norms based on the immediate interest of any commercial business: maximisation of profit.  This is where the difficulty lies as this powerful technology was introduced in many countries before any political control (democratic control) could be exerted.    Europe, largely, but narrowly, escaped the invasion after “a ‘war’ against genetically modified organisms” described by a journalist from Le Monde, Hervé Kempf, in his book ‘La guerre des OGM’.

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While the technology could be a useful tool for genetic improvement, the opacity in which it was introduced, the control of large trans-national industries on such sensitive issues as food production, combined with non-existent evaluations on long-term basis, have resulted in a poor acceptability which renders this technology unlikely for the improvement of the genetics of the vine, at least in Europe.

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Marker Assisted Selection (MAS) combined with genomic selection

 

This technique, also called Gene Chips or Microarrays technology consists of examining the genetic variations that have occurred over time during the process of domestication of the vine by identifying thousands of markers called SNP (Single Nucleotides Polymorphism) present in the genetic heritage of the vine. Marker Assisted Selection (MAS) is an indirect selection process where a trait of interest is selected, not based on the trait itself, but on a marker linked to it. To do this, rather than identifying genes that are responsible for the major traits of the vine (such as resistance to diseases, flowering, berry size, colour, taste etc), markers, which are tightly linked to genes are used as they are easier and more cost-effective to identify.   The markers obtained are then submitted to powerful computer software, to classify genes that are similar, or to classify them according to their sequence (hence their function) and to see if the variations are associated with a particular trait of the vine. This technique which consists in geno-typing (albeit indirect analyses of the gene) is now becoming cheaper and much quicker than phenotyping (i.e. waiting three years to assess the plant’s characteristics as with conventional hybridization).

 

So it is now quite conceivable that it will be possible to maintain the organoleptic characteristics of certain cultivars (who wants to see the Pinot Noir and Chardonnay characteristics disappear from Burgundy?) while modifying the genetic structure of the plant to make it resistant to pests, heat and drought. This, of course, implies obtaining markers from the great majority of known wild and domesticated varieties, selecting those traits that are wanted, hybridising on the basis of the MAS technology as many times as needed to achieve the desired traits in the plant, so expect 5-10 years before seeing the new technology bearing its fruits. The technology is promising.

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LIMITING THE USE OF WOOD, IN PARTICULAR NEW WOOD AND PRIVILIGING MATURATION IN LARGE VESSELS (DEMI-MUIDS, FOUDRES, AMPHORAS, EGGS ETC)

 

The use of wood, especially new wood, as we have known it for the last 50 years, has a tendency to add more weight to the wine as some wines tasted more of the oak than wine. Oak combined with an increase in alcohol brought about by climatic changes will undoubtedly contribute to the perception of an increased weight of the wine on the pallet.

 

However, the tendency of over-oaking has been reversed in the last ten years and the proportion of new oak is diminishing, and demi-muids, foudres and large vessels of any kind are more prominent in cellars.

 

INCREASE THE PERCENTAGE OF WHOLE BUNCH PRESSING IN THE MUST

 

This is a well known technique particularly in Burgundy, increasingly used over the last decade. It has its fans and its critics. The critics feel that it brings a certain greenness to the wine while the fans feel it brings a ‘lift’ to it. Sometimes it seems there is a certain time-lag between maturity of grapes and maturity of the stems and some growers gently dry stems before adding to the must. There is now little doubt that wine made with a high proportion of whole bunches taste more fluid, more refined than de-stemmed wine. It is certainly an easy technique and well worth trying, plus the climatic changes will bring a greater maturity to the stems.

 

LIMITING OR SUPRESSING MALOLACTIC FERMENTATION IN WHITE WINES.

 

It is of course a well-known tool to conserve acidity and freshness in the wine and needs no further explanation.

 

REMOVING ALCOHOL FROM WINES

 

Removing alcohol from the finished wine

 

Several techniques exist:

 

Membrane technique also known as reverse osmosis

 

The first filtration (Nano-filtration) is used to extract water and alcohol. These two components are then passed through a hydrophobic membrane (water- repellant), which allows the alcohol to be separated from water, the water is reintroduced to the wine to avoid over-concentration.

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Spinning cone technique

 

This is mostly used in Australia and California. Quite frankly, it is not a new technique as it was used in the 1930s in the nuclear industry to treat heavy water in nuclear reactors. This technique is very similar to a mechanical distillation under vacuum at an ambient temperature. The material consists of a vertical cylinder with two inverted cones inside through which the wine is passed. The first passage allows the aromas to be separated, the second passage is necessary to remove the alcohol. The aromas and the wine are then reconstituted, not very elegant, but it works.

 

 

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Partial removal of sugar from the grape juice.

 

This technique is very similar to the reverse osmosis technique. The purpose is to isolate part of the sugar that will not be fermented and therefore giving lower concentration in alcohol. The European regulation has approved a lowering of a maximum of 20% of alcohol for all wine while the French IRNA is trying to limit the reduction of alcohol to 2o for the AOCs (AOPs)

 

THE INCREASING USE OF SUBSTANCES FROM THE SYNTHETIC CHEMICAL INDUSTRY

 

The last 40 years have seen the invasion of synthetic substances, which can be used for making wine. There are, today, over 300 chemical substances authorized by the INAO that can be added to wine. These substances are mostly present in the commercial yeasts and have constituted the most important way of loading wine with artificial aromas. Increasingly, we consume drinks based on grape juice, but not wine as defined by the natural fermentation of the grape juice by natural yeast. The climatic changes, which in particular undoubtedly alter the organoleptic characteristics of wines at the cheaper end of the market, will increasingly push many domains to alter their wine artificially with chemicals. The actual division between wine of minimal intervention and industrial wine will gain in momentum. One of the prerequisites from consumers will be to make sure he or she drinks a wine made with natural yeast.

 

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