May 20, 2013

Carrots & Riesling. Advice for petrol lovers.

Do you like your Riesling wine with a distinct petrol character? Don’t want to wait many, many year to evoke it by cellaring? Then look for an Australien Eden or Clare Valley Riesling from a warm and sunny year, preferably from a bottle sealed with screw cap. And if you really want to be sure to get a hefty petrol bouquet, be sure to keep the bottle in 30° C for some time.


Researchers at The Australian Wine Research Institute (1) have investigated the factors influencing the level of TDN in Riesling wines. TDN is the abbreviation we ordinary petrol lovers can learn as the pronunciation of this aroma’s chemical name is a tongue-twisting exercise: 1,1,6-trimethyl-1,2-dihydronaphhalene. Some love it, others think TDN is a fault. 
Many factors interact to give Riesling wine higher levels of TDN. We will get there in a moment. But first some chemistry. Hang on now – this is exciting! 
It is an interesting fact that the level of free TDN in grapes and must is almost non-existing. Our lovely aroma is instead created later in the process. The basis for TDN is what is called carotenoids. Carotenoids? What? Well, there are in fact many kinds of carotenoids. You have probably heard of beta-carotene. The compound usually just called carotene, which gives carrots their beautiful orange colour. At least a dozen different carotenoids have been found in grapes, including the ordinary beta-carotene. Most of it is found in the grape skins, about three times as much as in the pulp. 
The carotenoids start to build up in the grapes right after fruitset. But when the grapes begin to change colour, at verasion, then the happy days of growth are over and shift into ruthless breakdown. In that process, small molecules are created. These C13-norisoprenoids also hold the compounds that generate TDN.
The C13-norisoprenoids are deeply in love. The object of their worship is sugar molecules and they cling hard to them. “Flavour reservoirs” are created this way. They will slowly release TDN during storage and thus also our lovely petrol aroma.
Higher level of carotenoids in the grape will thus give more petrol aromas. An interesting question is then if the level is possible to influence. Yes, according to the researchers, it is possible. The more direct sun and heat the grapes get, the more carotenoids. If vine leaves shade the clusters, then growth is hampered. The grower can consequently affect the TDN-level by canopy management. Besides the selection of pruning and trimming approach will the amount of fertilisers play a part, as more of it encourages foliage growth and thus more shade to the grapes. Correspondingly can drought and water stress reduce the foliage and as a result give more sun exposure.
Once the wine is in the bottle, the TDN-level grow through the “flavour reservoirs”. Also in this stage are several factors found to influence the development.
Apart from increased levels of TDN just by age, the storage temperature will contribute. Wine bottles cellared at 30° C have a considerably higher level of TDN than those stored at 15° C.
The higher level of acidity, the faster the petrol character develops. That is due to the breakdown of other aroma compounds in the acidity rich wine. Those compounds (monoterpenes and esters) give the wine its citrus, fruit and floral flavours and usually mask a part of the TDN.
Even the bottle closure affects the TDN-level. Studies have shown that natural cork and synthetic closures during a period of two years absorbed more than the half of the TDN. Screw caps on the other hand did not affect the TDN-level at all.
We petrol lovers should thus look for Riesling wines that
  • Were made of grapes exposed to heat and direct sunlight. Consequently, warm and sunny vintages are good choices. 
  • From producers not considering petrol to be a defect and because of that take additional steps to shade their grapes. 
  • Have a high level of acidity, which most Riesling wines have. 
  • Have screw cap.
  • Can we additionally suspect a warm freight and that the bottles have been stored on warm shop shelves, the chances increase. And why not use that otherwise so inappropriate wine storage place in the hot kitchen to serve as an extra TDN-activator?
Tim Adams Clare Valley Riesling 2011
We tasted a Tim Adams Riesling 2011, from Clare Valley in South Australia. Clare Valley is, just as neighbouring Eden Valley, well known for its Riesling wines, often showing a great petrol flavour. Even if 2011 was a colder year, with relatively few sunshine hours, we were satisfied with our choice. We found an incipient fine petrol character in terms of bicycle tubes. Dry, with a nice high acidity. Fruity with citrus, pears and barely ripe melon. Good minerality. Lovely long aftertaste with more inner tubes and citrus. Really good!
(1) Black, C. et al. (2012), "Aged Riesling and the development of TDN", Wine & Viticulture Journal, September/October 2012.

April 29, 2013

Holiday wine camp?

What about spending a week or two at a winery or with a grape grower? Wouldn't that be heaven for a wine geek? To live and learn wine in practice. An ultimate solution to enhance the knowledge of wine. And probably a very good one when it comes to remember the learnings.

The interest in food and wine seems to increase for each year. Thus not surprising that so many are attracted to wine tastings, wine classes and other events with knowledge replenishment as the common denominator. Wine can be so much more than just an enjoyable beverage. There are so much to learn. The history of wine, geography, grapes, chemistry, and so on. When the knowledge grows, presumably will also the ability to appreciate the wine even more do so too. And, not least, my experience is that knowledge nourishes friendship and pleasant social events around wine, and vice verse.

If I want to increase my knowledge, what are then my options? I want sustainable knowledge. I want to remember when I need it. For example when in a store and spontaneously want to buy a bottle. That name on the label in front of me, is it a wine from a renowned einzellage or is it from a large grosslage and thus probably a much more simple alternative? Or when at a tasting I want to through myself into the discussion about the wines and the effects of different winemaking techniques.

20%, so much (or little!) is considered to be remembered when we see and hear something, i.e. the usual situation when we listen to someone holding a lecture illustrated by some power points. Also a common situation when theoretical knowledge is imparted in wine class. At home, when distractedly reading a wine book, the risk is high that even less will be remembered.

What about multiplying the chance to remember with four? To achieve 80%, we need to make practical use of what we have learnt. Thus, in a wine class about winemaking, we ought to make some wine. Perhaps not that easy, but there could be other ways for the genuinely interested. (Now you can guess where I am heading, don't you? Yes, yes - the wine camp. It is coming, soon. Just let me develop my thinking.)

Myself, I prefer learning in a context of enjoyable experiences together with friends and wine enthusiasts. What are then the alternatives? My simplified learning/social experience matrix proposes four levels; grey, blue, green and golden yellow. What do we find on each level?

Both learning and the enjoyable experience tends to be low when sitting home, alone with the wine book. Grey, grey... inevitably down in the grey swamp in the bottom of the matrix. Just lifted up a tiny bit by a glass of good wine, poured to illustrate what I am trying to learn.

If I attend a wine class, or some other ordinary tasting held together with a lecture, I hopefully climb up into the blue field. Nice to be among other wine friends and a little bit more stays in my brain. Especially if the presenter speaks vividly and pedagogically and really ties the theoretical theme to the practical tasting. Can she/he season with personal experiences and anecdotes, the event will be even more informative. If the presentation is made by the winemaker her/himself, and there are opportunities for questions and discussion, then it can be really awarding.

To reach the green cloud, then I have to get out in the world of wine. To travel and visit producers. To see with my own eyes, talk, absorb the atmosphere. If I travel with an expert guide, especially if it is my first visit to the area, then the experience becomes even better. Informed visits and discussions with winemakers and growers increase learning even more. And the enjoyable experience will usually be great when spending time with like-minded.

How can I then reach the golden yellow sun in the upper right-hand corner? Where learning and enjoyable experience will be at the highest by making things. Out in the wide world of wine not just to see, meet and discuss. But also to try in practice. And at the same time get a wonderful experience for life.

Well, imagine if you could be an intern a week or two at a winery where the people love to share their knowledge. To be able to live and learn wine in practice. A kind of wine camp for grown ups. I would love it.

When will I see the first agency for "holiday wine internships" to wine geeks on the internet? A new business idea? Or is there already someone working with such a concept out there?

April 21, 2013

What wine do we enjoy in 2050?

2050 seems very far away. What are your plans for then? Myself, I hope to continue enjoying good wines all the time up till then. And be healthy enough to keep exploring all corners of the world of wine. But which wine do I have in my glass in 2050 and where do I travel?

In the perspective of my wine cellar, I'm about 20 years ahead of today. But now we are talking about an even more remote future. 37 years will pass by before we have 2050. Normally, it is only advertisements about various pension schemes that remind us of a future as distant as that. However, not this time. Now it is about wine. A team of scientists from the US, China and Chile have looked into the future to see how climate change can affect viticulture (1).

The results are remarkable. In their worst scenario, RCP 8.5 (note below), the area suitable for growing wine grapes might decrease with 25% to 73% by 2050 depending on location. At a lesser impact (RCP 4.5) the figures state a decrease between 19% to 62%. The highest number 73% relates to mediterranean climate parts of Australia. In Mediterranean Europe the net decrease in area suitable for viticulture is 68% and in California the decrease is 60%.

Bordeaux, Rhône, Tuscany and Piedmont are classical wine regions, all facing the future risk of getting a too hot to be suitable for wine grape production. Likewise Stellenbosch in South Africa, Colchagua and Maipo in Chile and the inner, warmer parts of California and Australia. You only have to take a look at the red spots on the map below. Many old wine favourites are threatened.

There are more interesting facts on the map. Green colour, as well as red, represents the present areas of viticulture. However, in the green parts, we can still hope for continued grape production. The dark green areas are the ones we can be most certain about. Here there is a very high degree of consistency from the results of the 17 different climate models used by the researchers, more than 90%. For the lighter green areas, more than half of the models give the result that the area will be suitable for wine grape growing also in the future. Thus, all lovers of wine from the Loire valley can calm down. The lighter green colour also covers parts of California, Chile, South Africa and Australia.

But maybe, in our twilight years, the stem will be filled with wine from a completely new viticultural area. The blue areas indicate where grape growing could be established successfully. Northern Europe is high on the list with a 99% increase of the suitable net area. In New Zealand and western North America, the growth is even higher with 168% and 231% respectively.

However, we can note that viticulture already today is successful in many of the blue areas . The used models and assumptions have not considered that many areas in the blue Germany have produced excellent wines for many centuries.

Myself, I find the pale blue border around the coasts of southern Sweden interesting. Maybe I could have a really nice, fine Bohuslän west coast wine in my glass in the year of 2050.


RCP stands for Representative Concentration Pathways. The RCP:s describe four different scenarios of  greenhouse gas concentration development over time. They are used by the Intergovernmental Panel on Climate Change (IPCC) and of other scientist making research about climate change. RCP 8.5 implies the highest impact, while RCP 4.5 represents the second lowest impact.

(1) Lee Hannah, Patrick R. Roehrdanz, Makihiko Ikegami, Anderson V. Shepard, M. Rebecca Shaw, Gary Tabor, Lu Zhi, Pablo A. Marquet, and Robert J. Hijmans (2013), Climate change, wine, and conservation, Proceedings of the National Academy of Sciences of the United States of America; PNAS 2013: 1210127110v1-201210127.