Apparently the South African palate is not as sensitive to green flavours as it should be and this has become a trait of our red wines. For years the issue of greenness in red wines has bothered De Grendel cellarmaster and well-known industry personality, Charles Hopkins and he has now decided to act on it.
Cabernet Sauvignon, Merlot and Cabernet Franc are usually the green culprits, with the former being most popular of the three in South Africa. At a tasting held at De Grendel, Charles presented six acclaimed South African Cabernet Sauvignons or blends based on that varietal and in the process proved that neither SA’s top winemaking corps, nor its critics and media are sensitive enough of greenness in wines.
The “greenness” of red wine can be attributed to 2-isobutyl-3-methoxypyrazine (IMBP), the same compound responsible for the green pepper character found in Sauvignon Blanc. The sensory threshold of IMBP is 2ng/L, while red wines with an IMBP of more than 10ng/L are considered to be green and a reading of above 40ng/L can be viewed as a wine fault.
In 2011 Charles started to analyse the IMBP’s of South African red wines, after the green flavours on his own wines, made from Durbanville grapes, concerned him. As part of this personal ‘green project’ he started analysing samples of top performing reds from other areas as well. And the results were often more than worrying.
Of the five top South African wines tasted at Charles’ green awareness media tasting, none had an IBMP below 10ng/L, while two were off the scale at over 40ng/L. Similarly, the tasters often preferred the wines that could even be faulted on the count of greenness.
Even though it seems clear that the domestic palate does not mind greenness, this character is often used as a means of identifying South African wines in an international line-up. And like the still-not-quite-solved burnt rubber issue of 2010, this is not an attribute to be proud of.
The solution is not that simple either. At De Grendel even experimental, super ripe Cabernet Sauvignon grapes, which had full sun exposure and were harvested at 28?B, still had unacceptable IBMP levels. In fact, Charles feels that there is no place for Cabernet Sauvignon in Durbanville and has now regrafted De Grendel’s Cabernet Sauvignon vines to other varietals, with Shiraz taking the spotlight as a red on the Estate.
The latter does not present such high levels of IMBP, even in cool areas. There is already a movement towards Mediterranean wine styles and varietals such as Shiraz, Grenache and Mourvèdre and the new focus on greenness is likely to further encourage this.
In the case of Cabernet Sauvignon, 53% of IBMP is extracted from stalks, while seeds and skins are the other main contributors, with only 1% coming from the grape’s flesh.
There are presumably no viable cellar solutions for green grapes at this stage. Thermovinification effectively reduces IMBP, but is not recommended for high quality products, while Charles adds that believing that adding tannins, staves or chips can hide greenness is one of the “myths” of this dilemma.
Other myths include the belief that greenness disappears with ageing, that pirazine’s greenness is only an odour that is not noticeable on the palate and that only certain clones produce high IMBP levels.
Testing IMBP levels is not simple, nor cheap. Individual tests cost R695 per sample at VinLab in Stellenbosch. It is best done on finished products for red wines, although must and wine can be tested for whites. VinLab’s Emanuelle Lapalies explains that they have been analysing IBMP for the last six years, albeit mostly for Sauvignon Blanc.
Charles strongly emphasises that this drive against greenness is not about a single variety, area or group. When asked why he is going through the effort of this greenness awareness campaign, where top wines with high IBMP’s are often exposed, he said that he owes it to an industry that has treated him well.
As the lab analyses indicate, there lies significant truth in his argument. These efforts have already played a role in the commencement of a post graduate study on the greening topic, while rumour has it that samples for IMBP analysis are already streaming in.