Who is Interested in Research on Grape Tannins… And Why?
Megan Hill, Ben Rowbottom and Geoff Kaine
Department of Primary Industries
Practice Change Research, Tatura
As a major contributor to red wine quality, tannins are of interest to both the vast majority of winemakers as well as the Australian wine industry in general. Consequently, there are currently a range of tannin projects being conducted by Australian research organisations. One of these projects is being undertaken by the Department of Primary Industry (DPI), Irymple with support from the Grape and Wine Research and Development Corporation.
Natural tannins are compounds that occur in the seeds, skins and stalks of grapes. These are an important component of red wine quality as they contribute to the structure, colour, complexity and mouth feel of the wine. Tannin can also be added in an exogenous form to grape juice in the winery to influence the characteristics of the resultant wine.
The DPI tannin research team is working on the identification and measurement of tannins, and developing protocols to modify tannins in the vineyard through vine manipulation. In order to better target their research and extension efforts, the tannin research team wanted to understand who in the industry will use their results and why. So they commissioned us, members of the DPI Practice Change Research group to conduct this study.
We interviewed grape growers, grower liaison officers and winemakers, from cool (Coonawarra), warm (Nagambie, Colbinabbin and Rutherglen) and hot (Sunraysia) wine grape producing regions. The interviews represented a range of business sizes, family and corporate businesses, producing wine at a range of quality grades and price points.
Growers were asked if, and how, they managed the tannin content of the grapes they were growing. Winemakers were also asked how the natural tannin content of the grapes influenced their winemaking practices, if, how, and when, they used exogenous tannin, and whether they encountered problems in relation to either natural or exogenous tannins. Everyone was asked about the role of tannins in determining the quality of their product.
Results
While some wine companies are providing feedback to growers about the tannin levels of their grapes, none of the growers said the prices they received for their fruit depended on tannin content, although we did hear of growers in a cool region missing quality bonuses due to the presence of green flavours or green tannins.
We found that winemakers and wine companies were very interested in talking about tannins and hearing about tannin research. The winemakers said that managing tannins was an integral part of their job as part of creating and maintaining wine quality and value.
Most of the winemakers stated that they use exogenous tannins in the winery in response to the natural tannin content of the fruit they are processing, and the product they are trying to make. By understanding this, we gained insights into problems associated with natural tannins, and hence the research outputs that would help solve these problems.
We grouped the winemakers and grape growers we interviewed into six market segments (see Figure 1). Some winemakers would be in a number of segments if they were processing fruit from a range of regions, or making a range of products. Oak barrels are not included in determining these segments as most winemakers considered exogenous tannins to be products in powdered or chipped form. The six market segments and information or research outputs that will be relevant to these segments are described below.
Segment 1- Stabilising wine colour
Segment one represents winemakers that were mainly seeking to stabilise wine colour through their use of exogenous tannins. These winemakers were mainly processing fruit from a hot growing region, which they said was often weak in colour, leading to light coloured wine, or wine with colour that deteriorated over time. This was seen as a major issue because consumers equate strong wine colour with a good quality product.
To manage this issue winemakers in segment 1 said they added exogenous tannins to most, if not all, parcels of fruit coming into the winery. As one winemaker told us;
“The fruit from this area does not have much colour or complexity. We add 200 ppm of VR supra tannin at the crusher to try to preserve what colour there is”.
Any complexity or mouth-feel characteristics the tannins provided was usually considered a bonus.
The problems that winemakers in this segment faced were that using exogenous tannins added cost to the winemaking process. Also, high tannin levels in the wine were not considered to be desirable, as many of the winemakers in this segment were making a “soft, fruity and easy to drink” style to be sold in the shortest possible time after production. And, most importantly the exogenous tannin did not always provide the stability of colour that was sought. As one winemaker said:
“Even when we use exogenous tannins we only end up with the strong, stable colour we want 70% of the time”.
Therefore if the DPI tannin research team can identify which tannins are important in stabilising wine colour, produce a method to measure them and protocols to modify these tannin levels in the vineyard, a substantial proportion of the wine industry will adopt these research findings. The development or refinement of exogenous tannins that are cheaper and/or fix colour more reliably would also be of interest to winemakers in this segment.
Segment 2- Green flavours
Segment two represents winemakers who used exogenous tannins to try to mask or modify green flavours. Green flavour describes a range of problems around bitter, astringent, or vegetative flavours in grapes and the resulting wines, which some winemakers described as being tannin related. This problem is more prevalent in the cooler regions or during cooler seasons.
The winemakers we interviewed said green flavours are a problem as the consumers often find them too strong and unpleasant. As a representative from a large company told us;
“We recently missed a major overseas contract because the buyer didn’t like the green characters in our Clare Riesling. That will impact on next year’s grower contracts in that region”.
Currently there are no winemaking techniques that are effective in removing green flavours and they are difficult to disguise through blending with other batches of wine. Consequently, the winemakers interviewed said that they minimise fruit with green flavours by: selectively harvesting and processing fruit, delaying harvest until the fruit is very ripe, reducing the time the fruit is on skins, and using exogenous tannins to provide other flavours, or soften the existing green flavours. The measures all add to the cost of production and compromise other aspects of wine quality.
We expect that winemakers and growers in segment 2 would be very interested in research that identifies how and why the green flavours occur, and more importantly how to measure and minimise these compounds. The development of exogenous tannins, or winery processes that are more effective in disguising, or removing green flavours would also be welcome for winemakers in this segment.
Segment 3- “Special” characters in the wine
Winemakers in segment 3 used exogenous tannins in conjunction with other wine-making processes to create wines with “special” characteristics, such as a European-style to distinguish their wines from competing wine brands. These winemakers were using fruit from cool to warm regions to produce high quality, high price point wines. For example one of the winemakers in this segment said:
“We have moved away from the Australian “fruit bomb”, to a more European style of wine. We use small parcels of fruit. We leave the wine on skins to give a richer, more complex, tannic style. We enhance this by using finishing tannins and the best oak barrels”.
The winemakers in this segment would be interested in innovations that enabled them to enhance their existing wine quality, features, or reliability, or add new features, such as novel flavours to their wine.
Segment 4- Risk management
Segment four represents winemakers that use exogenous tannin as a risk management tool. These winemakers were generally from small to medium sized wineries in warm grape growing regions. While the wine grapes being processed did not have obvious problems, these winemakers said they added exogenous tannins as they probably provided some quality benefits to the wine, the tannins were a small component of their input costs, and they had been adding tannins for many years and were reluctant to change this practice without knowing how it would change their wine. As one winemaker in this segment said:
“The tannins may fall apart and may not do what they are supposed to, but we add them anyway as they can’t hurt, and it is potentially risky to stop using them”
Winemakers in this segment will be interested in a new exogenous tannin that comes onto the market, if they perceive it is cheaper, provides an additional benefit or flavour, or is more effective than those they are currently using. These winemakers would also be interested in optimising the effect of the tannins they are using through information on the timing and selection of tannins.
Segment 5- Natural or organic wines
Segment 5 represents the winemakers who said that they did not use exogenous tannins as they were making “natural” style wines, usually from organically grown grapes and using minimal additives in the winery. These winemakers were from small wineries in warm regions, and will be interested in vineyard protocols to modify natural tannins in the grapes as they have fewer alternatives than their conventional counterparts to modify the tannins in the winery.
Segment 6- Excellent natural tannins
Winemakers in segment six also said that they did not use exogenous tannins, however this was because they believed that the grapes grown in their region had excellent natural tannins, making the use of exogenous tannins unnecessary. Again these winemakers were from small wineries, processing grapes with no major tannin related faults, grown in warm regions. These winemakers are unlikely to be interested in tannin-related research.
General findings
It became apparent during the interviews that there is an extensive range of exogenous tannins commercially available to winemakers, often with little or no information on what they are made from or how to best use them. This confused and frustrated many winemakers who said they did not know how to evaluate and select the tannins best suited to the grapes they were processing and the wine they were trying to make. As one winemaker told us:
“I spend half the time trying not to get excessive pip tannin, and then the salesman tries to sell it to me as exogenous tannin”
Some winemakers said they did not understand how tannins worked, with one winemaker describing the use of exogenous tannins as a “dark science”. Consequently there was a confusion and frustration about which tannins to use, when, and why.
Consequently, we believe opportunities exist to provide impartial information to the winemaking industry regarding:
- Exogenous tannins that are best suited to meeting the various winemaking objectives such as colour stabilisation, adding complexity, filling the middle palate etc.
- How to evaluate and select exogenous tannins in a small to medium sized winery
- How to optimise the performance and reliability of exogenous tannins
Conclusion
This study has provided insights into the market for exogenous tannins, thereby identifying additional opportunities for research, development and extension work. Additional work could be done to validate these segments and determine the percentage of industry that each of the segments represents. Meanwhile this work has confirmed that research by the DPI tannin research team is relevant, and important to a large sector of the Australian wine industry.
Acknowledgements
Thanks go to GWRDC for supporting this project, Mark Downey and Nicole Dimos, and to the people who generously allowed us to interview them.
For a copy of the full report to GWRDC or further information please contact Megan Hill at DPI-Tatura on (03) 833 5307 or email megan.hill@dpi.vic.gov.au
References
Figure 1: Typology of market segments based on the benefits sought by winemakers using exogenous tannins
Smoke research in King Valley
King Valley Vignerons, together with the Department of Primary Industry (DPI), Department of Sustainability and the Environment (DSE) and Environment Protection Authority are conducting research into the effect of smoke on grapevines and grapes.
The King Valley Wine Region was severely affected by the smoke from fires in the Alpine National Park in 2003 and 2006-07.
It is clear from previous experiences that severe intensity of smoke on vines results in fruit being affected, but there are many unknown issues.
KVV executive officer Wendy Batey said it has been determined that grapes do not absorb the smoke compounds directly. The chemicals are absorbed by the leaves and translocated to the berries.
"Part of the current research is focussing on this translocation process, as well as other issues such as the affects of varying levels of smoke intensity and hours of contact." Batey said.
While there is a long way to go with the research project, one outcome that has been flagged is the potential development of a barrier spray that might prevent the translocation of smoke compounds from leaves to berries.
"A number of King Valley growers left significant quantities of grapes on vines so that sampling could be done following the fuel reduction burns. A caravan containing sophisticated monitoring equipment was provided by the EPA to measure the intensity and content of the smoke. The results of this monitoring, together with berry, leaf and cane sampling and small-lot winemaking will all be studied by Dr Mark Downey of DPI.
"Growers and DSE will be waiting eagerly for the results of the research. King Valley growers were supporters of DSE's fuel reduction program. The difficulty is that DSE has a very small window of opportunity in which to conduct these control burns, and this is March and April. when grapes are almost ready for harvest. The results of this research will certainly help with planning of burns for the future:' Batey said.
Mark Downey of the Victorian DPI said gelling growers to leave a bit of fruit on vines [to assist with the research] wasn't been a problem.
"The KVV has been fantastic at co-ordinating this, collecting samples and harvesting fruit for small scale winemaking. They have also organised for the EPA to collect some air quality data for us during the controlled burns by DSE (Dept. of Sustainability & Environment Vic.).
"Some of this wine will go to Adelaide University for analysis by two PhD students working with Kerry Wilkinson at the Waite Campus," Downey said.
Downey said the DPI was very excited about the potential for research outcomes from future work in this area, one outcome that he flagged as a possibility was the development of a type of barrier spray that prevented translocation of the smoke compounds to fruit.
"Ideally, yes some sort of barrier spray would be great, but I think that's a little bit down the track yet,' he said.
