Sending samples for analysis in Victoria
DPI Victoria’s Farm Services Victoria - Grapes Team, has established a single permit for Plant Health Certificates to assist growers or wineries wanting to send fruit to the AWRI, Vintessential or Chemical Analysis for testing.
Growers or wineries who wish to sample their fruit for testing levels of smoke taint ‘indicator’compounds guaiacol and 4-methylguaiacol, and who might need assistance with the preparation, processing and transport of these samples should contact either Ricky James or Kieran Murphy from DPI Victoria for instructions and further assistance. As the the AWRI is located in Adelaide, South Australia all grape samples that are sent are bound by Phylloxera protocols and must be accompanied by a Plant Health Certificate as issued by the Plant Standards branch of the Victorian DPI. A Plant Health Certificate can only be issued if the samples have been frozen at -18°C for a period of 24 hours in an approved facility. Depending on demand, the DPI Grapes Team will take delivery of fresh samples at a number of central locations for processing as per Plant Standards requirements and shipped in bulk to the AWRI,Vintessential or Chemical Analysis.
There are three facilities where growers or wineries can leave samples: Punt Road Wines in the Yarra Valley, Mitchelton Wines at Nagambie and the DPIVictoria offices at Rutherglen. Growers and wineries must complete the paperwork provided detailing name, address, variety, block, fax, email, etc. The procedure for the collection of samples is outlined below.
At this stage, shipments to the AWRI/Vintessential/ Chemical Analysis will be on Tuesday and Thursday evenings. Be mindful that fruit needs to be frozen for 24 hours prior to shipping, so samples due for shipment on Tuesday or Thursday for example, will need to be in freezer by 12.00 pm (midday) the previous day at the latest. The delivery of chilled or already frozen samples will ensure the samples are dispatched ASAP.
Delivery procedure:
Yarra Valley- Punt Road Wines- Delivery of samples is strictly from 9:00 am to 5:00 pm. Samples are to be taken directly to the freezer and signed in with all information recorded. Samples left in the laboratory will not be accepted. For further details contact Kieran Murphy on 0408 591 858.
Nagambie- Mitchelton Wines- Delivery of samples is strictly by appointment only. Please contact Ricky James on 0447 341 373 to arrange a time to deliver samples. North East- DPI Rutherglen- Delivery of samples is strictly between 9:00 am and 12:00 midday on Mondays and Wednesdays. For further details contact Ricky James on 0447 341 373.
Samples from Phylloxera Exclusion Zones and Phylloxera Restricted Zones areas can be delivered into these areas for collection. Please ensure that each sample to be tested is double bagged in the appropriately sized clip-lock bags.
Both the inner and outer bag will need to be labeled with adhesive labels stating the grower’s name, address,variety and block details. The contact details and address for each sample submitted is required to facilitate invoicing from the AWRI/Vintessential/ Chemical Analysis for the service.
Sending samples for analysis in NSW
For those growers or wineries in NSW wanting to submit samples to the AWRI for analysis, the NSW Department of Primary Industries (DPI) has established a ‘Movement conditions of wine grape samples from NSW to South Australia for smoke taint testing’protocol. The protocol can be downloaded from the National Wine Grape Industry Centre (NWGIC)
Results and interpretation
Results from laboratory analysis of guaiacol and 4-methylguaiacol are typically reported back in terms of micrograms per litre (µg/L) for each compound. The limit of detection is set at 1 µg/L in grapes and wine, with an uncertainty of ±1.0 µg/L or ±10% (whichever was greater). For samples where the laboratory has reported ‘not detected’or ‘below the limit of detection’ this means that the compounds in the samples have not exceeded the 1 µg/L level. The sensory threshold (that is, the level under which the compounds are unlikely to be smelt) in sparkling juice base is approximated at 6 µg/L. For finished wine, the sensory threshold largely depends on the wine’s structure; winemakers have observed smoke taint levels, in lighter red wine styles, of 12-15 µg/L.
Grapes and leaf samples are recorded in units of micrograms per kilogram fresh weight (µg/kg). The limit of detection is set at 1 µg/L in both grapes and wine, with an uncertainty of ±1.0 µg/L or ±10% (whichever was greater). It should be noted, however, that a finding of low concentrations in grapes at harvest is not a guarantee that any wine made from those grapes will be free from smoke taint. Also, low concentrations in young wine is not a guarantee that wine will not exhibit ‘smoke taint’ sensory characters as the wine ages.
What can winemakers do to mitigate the impact of smoke taint in the final wine?
Processing at cool temperatures, hand harvesting, bunch pressing and shorter skin contact during are beneficial. Carbon has proven to be effective at removing smoke taint characters in white juices, although its action is non selective and care should be taken. Carbon will also remove grape characters. Refer to the Winemaking and Extension services team at the AWRI for more information. Post fermentation techniques such as reverse osmosis have also shown shown positive results in reducing guaiacol and 4-methylguaiacol in wines (Wilkinson, 2009). There have also been some early indications that exogenous tannin additions may also aid in the management of the problem in wines. However, this last point is still very much under investigation.
Key references
•Kuchel, J. (2003). Trials to extract smoke compounds from grape berries before harvest. Technical report produced for the Alpine Valleys Winemakers and Grapegrower Association. Conducted by Vignoble Monitoring Services, 23 pages.
•The Australian Wine Research Institute (2003). Annual report 2003. Glen Osmond, South Australia.
•Krstic M.P. and Whiting J. Understanding the sensitivity to timing and management options to mitigate the negative impacts of bush fire smoke on grape and wine quality –Scoping study. Victorian Department of Primary Industries, 2007, 59 pages.
•Kennison K.R., Wilkinson K.L., Williams H.J., Smith J.H. and Gibberd M.R. (2007) Smoke-derived taint in wine: Effect of postharvest smoke exposure of grapes on the chemical composition and sensory characteristics of wine. J. Agric. Food Chem. 2007, 55, 10897-10901.
•Kennison, K.R., Gibberd, M.R., Pollnitz, A.P. and Wilkinson, K.L. (2008) Smoke derived taint in wine: the release of smoke-derived volatile phenols during fermentation of merlot juice following grapevine exposure to smoke. Journal of Agricultural and Food Chemistry 56, pp. 7379-7383.
•Krstic, M.P. (2008) Smoke taint workshop. Proceedings of the 2nd smoke taint technical workshop. Final report to the GWRDC for project number GWR 07/07, 44 pages.
•Kennison, K., Wilkinson, K. and Gibberd, M. (2009) Latest Developments in the Investigation of Smoke Derived Taint in Grapes and Wine. Factsheet produced by Department of Agriculture and Food Western Australia, University of Adelaide and Curtin University, 7 pages
•Wilkinson, K. (2009) Amelioration of smoke taint derived taint in wine by membrane filtration and solid phase adsorption. Final report to the GWRDC for project number RD 06/04-2, 28 pages.
•Kennison, K., Wilkinson, K., Pollnitz, A., Williams, H. and Gibberd, M. (2009) Effect of timing and duration of grapevine exposure to smoke on the composition and sensory properties of wine. Australian Journal of Grape and Wine Research (in press).
Authors:
Con Simos & Sarah Ballantine (AWRI), Mark Krstic (GWRDC), Joanne Butterworth-Gray (VWIA), Ricky James, Kieran Murphy and Pam Strange (DPI Victoria), Kristen Kennison and Glynn Ward (DAFWA), Kerry Wilkinson (University of Adelaide) and Duncan Farquhar (NWGIC)
