This month we are featuring a Riesling that we found very unique and intriguing. Most of the Rieslings that we have featured in the past have been young, sweet or dry. All have been quite enjoya
ble and well received by our club members. This time however, you will notice a distinct difference in our selection. The character that really stands out in the Coeur de Terre 2006 Riesling is the so-called “petrol” note. This aroma can be somewhat polarizing. The Alsatians refer to it as “gout de petrol” which is a great term if you enjoy it. If you don’t, then like some, you may just refer to it as “kerosene.”
Sometimes a very young Riesling exhibits a nose and to a lesser extent, a flavor that is best described as “petrol-like,” a term that suggests a slightly oily, petroleum or kerosene overtone, which is more appealing than it sounds and is highly appreciated among Riesling collectors. When Riesling is young, it usually has only a very slight petrol character. A classic aged German Riesling (the real ones, not those that are created and sold to the English-speaking world), have a pronounced petrol character. A true lover of Riesling will find this character highly desirable and they prize it greatly.
What gives Riesling the petrol note? Well, it’s interesting but technical. If you are like me, I don’t really understand the chemistry behind it; but I will attempt to explain it to you without putting you to sleep. The aroma compound we are talking about is known as 1,1,6-trimethyl-1,2,dihydronaphtalene…otherwise known thankfully, as TDN. TDN is not often found in grape juice or in young wines. It originates from the gradual breakdown of protective plant molecules known as carotenoids.
Carotenoids are pigments that absorb light. They are important in leaves to support photosynthesis (once the chlorophyll is gone from leaves in the fall, they give the leaves their orange, yellow and red colors). In the berries, these compounds absorb UV rays that would be harmful to the DNA and other cellular components.
A good way of thinking about this is to think of carotenoids as grape sunscreen. When UV light is high, carotenoids build up during berry development to shield the cells from the harsh rays. Near the end of the growing season, the molecules break down into smaller components, some of which are precursors to very powerful aroma compounds. These aroma compounds are often bound to sugar groups and known as glycosides. Glycosides are not aroma-active, so they won’t be observable by smelling or tasting. However, during fermentation, yeast enzymes liberate glycoside-bound aroma compounds, helping to create the complex bouquet that we love about wine.
TDN is created during the aging process from carotenoid precursors (terpenes) by acid hydrolysis. The initial concentration of precursors in the wine determines the wine’s potential to develop TDN and petrol notes over time. Factors that are likely to increase the TDN potential are:
- ¨ Ripe grapes (accentuated by low yields and/or late harvest)
- ¨ High light exposure
- ¨ Water stress, which is most likely in regions that don’t practice irrigation. This primarily occurs in dry vineyard sites during warm and low-rain years
- ¨ Warm soils
These factors are considered to contribute to high-quality Riesling wines. The petrol note is in fact, more likely to develop in top Riesling wines than in simpler wines made from high-yielding vineyards. Riesling grown in warmer climates, such as Alsace, will tend to exhibit the petrol character earlier in their post-bottling development. In addition to the intensifying and complexity of aromas, bottle-aging induces Riesling’s famous petrol aroma. If you have ever siphoned-off petrol, you will know that its strong vapor has nothing in common with the classic petrol aroma of a mature Riesling. It does not literally smell or taste of petrol. For those who really enjoy the honeyed richness of a great Riesling, petrol is one of the most recognizable words used to describe its classic aroma.
I find the petrol character highly desirable. I know that if I put a dry vineyard estate Riesling in my cellar for 6-7 years, petrol will likely develop. But I also know that not everyone has developed a taste for this. Therefore, a discreet amount of petrol aromatics is a great enhancer, too much can be a bit of a turn-off. I think that those who enjoy the taste of really strong and aged cheeses tend to like this type of Riesling. Those who lean more toward lightly flavored foods do not like it. What is very interesting about this type of Riesling is that it pairs beautifully with a large variety of foods.
When you experience this type of wine, keep an open mind, get past the initial shock of the “petrol” aroma and enjoy what it does to your palate when paired with a great meal. If you don’t like the petrol character, then a good rule of thumb is “DON’T AGE RIESLING!!!” They will develop this characteristic more as you age them.
