The Australian Wine Research Institute Blog
AWRI 2013 Webinar Series
4 June 2013 >Webinar is an interactive tool enabling you to participate in a live seminar from your desk using a computer with Internet access.
The AWRI’s webinars cover a range of winemaking, winery management and viticulture topics. Each webinar consists of a presentation followed by a Q&A session and is held on a Tuesday at 11:30 am Australian Central Time (Adelaide, GMT+9:30).
Register now to participate in the upcoming webinars:
Presentation: Proctase – a viable alternative to bentonite for protein stabilisation of white wines
Presenter: Matteo Marangon (The AWRI)
Date: 11/06/2013
Presentation: Crush, macerate, drain and press. The effect of juice processing on polysaccharide content and the mouth-feel of white wine
Presenter: Richard Gawel (The AWRI)
Date: 18/06/2013
Presentation: Fermentation control with computer simulation
Presenter: Richard Muhlack (The AWRI)
Date: 26/06/2013
Presentation: Optimising your laboratory for the best results
Presenter: Eric Wilkes (The AWRI)
Date: 23/07/2013
Presentation: Strategies for reducing alcohol levels in wine
Presenter: Cristian Varela (The AWRI)
Date: 30/07/2013
Presentation: The latest on CMCs
Presenter: Eric Wilkes (The AWRI)
Date: 6/08/2013
Presentation: Till death do us part: Cell death in the grape berry as a quality measure
Presenter: Steve Tyerman (The University of Adelaide)
Date: 20/08/2013
Presentation: Climate influence and trends for the wine industry
Presenter: Darren Ray (Bureau of Meteorology)
Date: 27/08/2013
Presentation: Hybrid Yeast: New Yeast for the New World
Presenter: Jenny Bellon (The AWRI)
Date: 03/09/2013
Presentation: Vines for the times: Proactive and reactive canopy management techniques
Presenter: Catherine Kidman (Treasury Wine Estates)
Date: 10/09/2013
Presentation: Management of eutypa dieback in grapevines
Presenter: Mark Sosnowski (South Australian Research & Development Institute)
Date: 17/09/2013
Presentation: Recent advances in yield forecasting: rapid, reliable estimation tools
Presenter: Greg Dunn (National Wine and Grape Industry Centre)
Date: 24/09/2013
Presentation: Advances in phylloxera detection and management with rootstocks and quarantine
Presenter: Kevin Powell (The Department of Environment and Primary Industries Victoria)
Date: 01/10/2013
Presentation: The effects of metals on the evolution of volatile sulfur compounds during wine maturation
Presenter: Marlize Viviers (The AWRI)
Date: 8/10/2013
Presentation: Rootstocks for Australian conditions
Presenter: Rob Walker (The Commonwealth Scientific and Industrial Research Organisation)
Date: 8/10/2013
Presentation: Thinking outside the bottle: Insights on how Chinese consumers choose wine
Presenter: Patricia Williams (The AWRI)
Date: 22/10/2013
Presentation: Great wines begin in the nursery
Presenter: Nick Dry (Yalumba)
Date: 5/11/2013
Presentation: Post bottling effects of early oxygen exposure during red winemaking
Presenter: Martin Day (The AWRI)
Date: 12/11/2013
Presentation: Benchmarking regional vineyard soil health
Presenter: Ian Porter (The Department of Environment and Primary Industries Victoria)
Date: 26/11/2013
Presentation: Managing heat events in your vineyard
Presenter: Mike McCarthy (South Australian Research & Development Institute)
Date: 3/12/2013
Presentation: Greenhouse gas emissions in vineyards
Presenter: Mardi Longbottom (The AWRI)
Date: 10/12/2013
Further information or to register
For further information or to register, please visit our website at https://www.awri.com.au/industry_support/courses-seminars-workshops/webinars/.
Registration confirmation
After registration, you will receive a confirmation email with a link to join the session.
System requirements
You will need a computer with Internet connection. Participants can dial in via the provided number or audio is connected via your computer’s microphone and speakers (Voice over IP – VOIP). A headset is highly recommended.
Further information
Please contact infoservices (infoservices@awri.com.au).
eNews – May 2013
7 May 2013 >What’s the dirt? Hunter Valley Semillon Project: putting science into the subregions
Cool runnings
Launch of AWRI’s new workshop – Adapting to difficult vintages
Do you use refractometers to determine wine grape price? If so, these changes affect you.
Coonawarra trial highlights the power of vintage
New speakers confirmed for WINEHEALTH 2013
Introducing a new breed of wine yeast
Interact with the experts at AWITC workshops
Can you help enhance the Agrochemical App?
Grape marc – a surprise contributor to greenhouse emission reduction
Sign up for sensory sessions
Recent literature
What’s the dirt? Hunter Valley Semillon Project: putting science into the subregions
As in other premium Australian grape growing regions, Hunter Valley winemakers are increasingly focussing on producing single vineyard and subregional wines to express the unique characteristics they are seeking. Up until now, however, the belief amongst Hunter winemakers that vines grown on the four main soil types in the region produce fruit with different flavour, style and phenolic profiles hasn’t been tested either on the tasting bench or in the lab. The Hunter Semillon project, coordinated by Sam Connew at the AWRI’s Hunter node, aims to investigate whether soil type (and thus subregion) plays a significant role in the flavour profile of Semillon wines and to explore the impact of phenolics on both juice and wine characteristics.
The first stage of the project was a formal tasting of 55 single vineyard wines from 2011 and 2012, set up to investigate the descriptive terms used to describe differences between wines originating from different soil types and sub regions. These wines were also analysed for basic wine chemistry to determine any significant trends.
In the 2013 vintage, fruit samples were collected from over 20 different vineyards and the resultant juices assessed for phenolic profiles. Fruit samples from five of these vineyards were then processed identically and the resulting wines were also reviewed for phenolic profiles. Initial data collected on the juice samples using key UV-Vis wavelengths indicated that grapes grown on different soil types contained different phenolics and that hydroxycinnamates might be an important class of compounds responsible for the differences seen between the samples. The implications of this for Hunter Valley Semillon are important, as one of the characteristics of hydroxycinnamates is that they are powerful antioxidants and give white wines good ageing potential. This study has so far shown that soil type and subregional characteristics have a role to play in wine phenolic profiles.
The latest results from this project will be presented on 16 July in a workshop ‘The terroirs and tastes of Hunter Semillon’ at the 15th Australian Wine Industry Technical Conference. The workshop will include a tasting of single vineyard Hunter Semillons and will also feature a classic Hunter vs Barossa match-up of Tyrrell’s Vat 1 Semillon vs Peter Lehmann Margaret Semillon.
Cool runnings
Electricity prices are rising. As this vintage comes to an end, it’s timely to think about taking steps to reduce winery electricity costs. Perhaps by moving some electricity use to cheaper off-peak periods, by arranging a better deal on electricity from another provider, or obtaining a government subsidy to insulate tanks? Refrigeration is the major component of most winery electricity bills and therefore a good area for focus. For some general ideas on refrigeration, check out the AWRI’s short reference guide.
Launch of AWRI’s new workshop – Adapting to difficult vintages
The AWRI will launch a new workshop ‘Adapting to difficult vintages’ in the Barossa Valley on Wednesday 15 May and in the Clare Valley on Tuesday 21 May. This workshop, developed for both grapegrowers and winemakers, focuses on coping with extreme weather conditions. Topics covered include heatwaves, bushfire, drought and excessive rain.
Participants will learn about the latest adaptation techniques for a wide range of weather-related events, both in the vineyard and in the winery. Presentations will discuss strategies to deal with drought, salinity, extreme heat, bushfires, smoke taint, processing very ripe fruit and avoiding stuck fermentations. Tactics for dealing with a compressed vintage and the associated logistical pressures will also be covered, giving participants a chance to share their experiences from vintage 2013.
Information will also be provided on growing grapes and making wine in wet seasons, including dealing with floods, high disease pressures including Botrytis, the impact of laccase and effects on filtration. The workshop will explore energy use and efficiency savings in the winery, waste water management, and will include practical exercises and tastings of regionally-suited alternative variety wines. To register, or to check out future dates and locations for this workshop, visit the AWRI Events Calendar or the Grape and Wine Events Calendar.
Do you use refractometers to determine wine grape price? If so, these changes affect you.
The National Measurement Institute (NMI) is working with a number of stakeholders in the wine grape industry, including the AWRI, on changes to the rules for refractometers. The changes will ensure that those instruments used to determine the unit price of wine grapes are accurate, traceable and comply with relevant legislation. Transitional arrangements are being provided for refractometers that are currently in use by industry. Action is required before 30 June 2013.
NMI, part of the Department of Innovation, Industry, Climate Change, Science, Research and Tertiary Education, is the peak Australian measurement body responsible for biological, chemical, legal, physical and trade measurement. NMI is responsible for Australia’s units of measurement and the development and maintenance of standards of measurement, reference materials and reference techniques. NMI provides a variety of services to industry and government, including calibration, measurement, analysis and training.
As part of the new process for refractometers, instruments will need to comply with the national standard NMI M 9. With the introduction of the standard, growers and wineries can be reassured that new refractometers will undergo thorough testing, verification and approval to make certain that they are suitable for use and maintain their accuracy over time.
Under transitional arrangements, refractometers that are currently used by industry can be considered for approval on a restricted basis, known as ‘grandfathering’. This will allow existing instruments to continue to be used for trade on or after 1 January 2014. Following grandfathering, instruments will need to be verified prior to their use.
To apply for grandfathering, please submit an application by 30 June 2013 to roselle.mailvaganam@measurement.gov.au.
The application should include the following details for each type of refractometer:
- make and model
- specifications including:
- accuracy class – digital handheld device (type III), digital bench top device (type II) and automatic refractometers capable of making continuous measurement without operator intervention (type I).
- measurement unit
- temperature compensation facility
For more information, please contact Ms Roselle Mailvaganam on (02) 8467 3832 or roselle.mailvaganam@measurement.gov.au.
Coonawarra trial highlights the power of vintage
A four-year trial carried out in conjunction with Wynns Coonawarra Estate has highlighted the significant impact that vintage weather conditions can have on the development of colour and tannin levels in red grapes. Average temperature during the growing season was the most significant factor in increasing the tannin levels achieved in the grapes at harvest. The trial also studied the effect of soil type and clonal differences on the phenolic profiles of Cabernet Sauvignon, but neither had a consistent impact on the accumulation of tannins or anthocyanins in the grapes across the four vintages.
This trial assessed the impact of vintage, soil type and clonal differences on the phenolic profiles of Cabernet Sauvignon grapes grown in Coonawarra from 2009 to 2012. Five Cabernet Sauvignon clones: CW44, G9V3, Reynella, LC10 and SA125, grown in one Coonawarra vineyard with two soil types (Terra Rossa and Ground Water Rendzina) formed the basis of the trial. Parcels of fruit were processed using identical winemaking techniques in order to compare the phenolic profiles of the resultant wines.
The impact of average temperatures experienced during the growing season was the most significant factor for tannin development in the grapes, with warmer vintages producing fruit with higher tannin levels and lower anthocyanin levels. Grape tannin and colour levels at harvest also had a significant influence on colour and tannin levels in the resultant wines. High colour levels in the wines were only achieved when the grapes contained comparatively high levels of anthocyanins AND tannins.
Tannin concentration at 3-4 weeks before harvest proved to be a good indicator of tannin concentration at harvest and could therefore be used to optimise picking times to achieve a desired target tannin level in the grapes. Neither clonal type nor soil type was found to have a consistent impact on the accumulation of tannins or anthocyanins in the grapes across the four vintages.
The wines produced during these four vintages were significantly different in terms of their colour and tannin concentrations, even though identical winemaking techniques were used, and this was reflected in the sensory assessment ratings assigned by Wynns. Wines produced from clone SA125 grown on Terra Rossa were consistently the most preferred from each vintage. Soil type did appear to influence wine sensory characteristics and resulting preference in some cases; clone CW44 generally performed better on Rendzina whilst clones Reynella and G9V3 performed better on Terra Rossa soil.
A detailed summary of this work will be presented in the June edition of the AWRI’s Technical Review and outcomes will be presented through a series of posters at the upcoming AWITC in Sydney. For more details, contact Neil Scrimgeour.
New speakers confirmed for WINEHEALTH 2013
Professor Ramon Estruch from the University of Barcelona and Associate Professor Leon Simons from the University of New South Wales have recently confirmed their participation in WINEHEALTH 2013. Their presentations will be two highlights of many within the program of this international conference on the complex relationship between wine consumption and health. Prof Estruch studies the effects of alcohol consumption on the human body and A/Prof Simon is the Principal Investigator of Australia’s longest running study of healthy ageing. WINEHEALTH 2013 takes place in Sydney from 18-20 July 2013, immediately following the 15th AWITC.
Prof Estruch will present in the ‘Wine and cardiovascular disease’ conference session, focusing on a recent study comparing the effects of red wine, dealcoholised red wine and gin on cardiovascular markers. A/Prof Simons will present in the conference session that covers epidemiological evidence on the relationship between alcohol consumption and human health. Other sessions will include ‘Grapes, wine and nutraceuticals (omics)’, ‘Integrated Medicine – Healthy Ageing’ and ‘Our daily diet and lifestyle – interactions with wine’. To register or for more information, please contact Kate Beames on +61 (0) 8 83136821 or visit the conference website.
Introducing a new breed of wine yeast
Question: How can we reap the benefits of complex flavours and aromas derived from spontaneous fermentations while minimising the risk of spoilage?
Answer: Breed complexity into our wine yeast!
The AWRI has generated a new breed of wine yeast by interspecific hybridisation between a robust Saccharomyces cerevisiae wine yeast strain and Saccharomyces mikatae, a species not before associated with industrial fermentation.
By using a robust S. cerevisiae wine yeast as one parent, the hybrid yeast inherit the fermentation properties necessary for industrial usage whilst delivering novel, and wider ranging, yeast-derived flavours from the S. mikatae parent.
Chardonnay wines made with the new hybrid yeast showed different concentrations of volatile compounds known to contribute to wine flavour and aroma including flavour compounds associated with non-Saccharomyces species. The new S. cerevisiae x S. mikatae hybrids therefore have the potential to produce complex wines akin to products of spontaneous fermentation while giving winemakers the safeguard of an inoculated ferment. You can find out more on this development in the June issue of Australian & New Zealand Grapegrower and Winemaker or by contacting Jenny Bellon.
Interact with the experts at AWITC workshops
The 15th AWITC is coming up fast and the workshop program is always a major highlight. There are 44 interactive workshops on offer, covering topics from winemaking, viticulture and the environment, to business, social media, wine law and regulatory information. The workshop program is your one chance to get up close and personal with experts in all of these fields. To find the workshops you just can’t miss, check out all the details in the workshop program.
Workshop places always fill fast, particularly for the most popular topics and tastings. ‘Perfecting Pinot Noir’, wine texture and environmental issues are hot topics at the moment. Register today to make sure you don’t miss your first choices.
Some of the top selling workshops include:
| W01 | Perfecting Pinot Noir |
| W03 | Organic viticulture |
| W07 | Key wine aroma compounds: their origin, aroma properties and how to dial them up or down |
| W13 | The power of non conventional yeast in fermentation |
| W14 | Making wine with lower alcohol |
| W15 | The effects of oxygen exposure during winemaking and packaging on wine style |
| W16 | Microbial spoilage of wine |
| W18 | Environmental sustainability – where are we now and what are the drivers? |
| W19 | How to interpret soil health tests to improve vineyard performance |
| W22 | Pushing quality up and keeping costs down. Practical information for maximising profitability in the vineyard |
| W25 | Emerging varieties: what is the latest? |
| W26 | Vine balance: how to get the best out of your vines? |
| W28 | Fermentation is in your hands: processes and oenological tools for quality, wine style and consistency |
| W32 | Malolactic fermentation – flavour and efficiency |
| W34 | Influences on texture and in-mouth sensory properties of red and white wines |
| W42 | Measures of quality from the vineyard to the winery |
Can you help enhance the Agrochemical App?
The AWRI Agrochemical Search app gives growers access to ‘Dog Book’ Agrochemical information on-the-go via mobile phones or tablets. The user selects the target pest or disease and the growth stage of the vine to receive a list of recommended active constituents and products registered in Australia. Since its release in November 2012, the app has been downloaded onto over 500 devices and been used for more than 2,300 searches. It can be downloaded for free from iTunes or Google Play.
An upgrade of the app to give further assistance to growers is now underway. To make sure this upgrade is as useful as possible, feedback from current app users is essential. Please complete this very short survey and have your say about the types of functions or information that would help you make spray decisions. Thank you for helping to improve the app!
Grape marc – a surprise contributor to greenhouse emission reduction
When thinking about reducing Australia’s greenhouse gas emissions, a winery by-product might not be the first thing to come to mind. It seems, however, that the tannins contained in grape marc may have an important role to play.
Grape marc, the left over skins and seeds from the wine making process, contains tannin and lots of it. When fed, as a dietary supplement, to cattle or other ruminant animals grape marc has been shown to reduce methane emissions. This is great news as methane emissions from enteric fermentation (livestock digestion) is estimated to contribute 10% of Australia’s national greenhouse gas emissions. Also, it looks promising for cattle farmers too as the reduction in methane loss during the digestion process may be linked to an increase in liveweight gain and hence in productivity.
As one of many research organisations participating in the National Livestock Methane Program (NLMP); the AWRI is working towards characterising different types of grape marc and assessing its performance and suitability as a methane reducing feed supplement. An additional objective is to identify if there are potential risks associated with agrichemical residues within grape marc.
Over the last six months the AWRI has developed and refined analytical techniques and methods that enable tannin levels and composition to be understood and quantified in grape marc. These analytical techniques have revealed the incredible diversity of both tannin type and tannin concentration in grape marc. The next stages of the project will use digestion simulation methods to quantify the methane suppression and productivity enhancing properties of different tannin types.
The project is supported by funding from the Australian Government Department of Agriculture, Fisheries and Forestry as part of its Carbon Farming Futures Filling the Research Gap Program with management support from Meat & Livestock Australia. For more information on this project contact: Karl Forsyth or Josh Hixson.
Sign up for sensory sessions
Two Advanced Wine Assessment Courses will be held in Adelaide in October 2013. Register your details here to make sure your name goes into the ballot for course places. The AWAC is a must for aspiring wine judges and anyone in the wine sector wanting to take their tasting skills to the next level. Want to know more? Course details are here, or you can peruse a previous course program or express your interest at awac@awri.com.au or (08) 8313 6600.
Recent literature
John Fornachon Memorial Library at the AWRI delivers journal articles and loans books to Australian grapegrowers and winemakers. Books can be searched and requested via the Library catalogue – or you can email the Library with your request. A list of recent AWRI publications follows.
- To order AWRI staff publications and articles from Technical Review please contact the Library.
- Articles and books on specific topics can be searched for and ordered via the Library catalogue
- To request a Literature search on a specific topic contact the Library via email or telephone (08) 8313 6600.
Recent AWRI staff publications
Borneman, A.R., McCarthy, J.M., Chambers, P.J., Bartowsky, E.J. Comparative analysis of the Oenococcus oeni pan genome reveals genetic diversity in industrially-relevant pathways. BMC Genomics. 13: 1-13; 2012.
Capone, D.L., Francis, I.L., Herderich, M.J., Johnson, D.L. Eucalyptus aromas: a mystery. Researchers confirm source behind minty characters. Wines & vines 94 (2): 52-57; 2013.
Curtin, C., Cordente, T. Flavour-active wine yeasts: little things that have a big impact. Australian & New Zealand grapegrower & winemaker (589): 54-56; 2013.
Dry, P. Ask the AWRI: What can you tell me about controlling Botrytis bunch rot without the use of fungicides? Australian & New Zealand grapegrower & winemaker (589): p.28; 2013.
Dry, P. Sagrantino. Wine & viticulture journal 28 (2): p.53; 2013.
Dry, P. Can the production of low alcohol wines start in the vineyard? Wine & viticulture journal 28 (2): 40-43; 2013.
Gawel, R., Day, M., Schulkin, A., Smith, P., Herderich, M., Johnson, D. The science of texture. Wine & viticulture journal 28 (2): 30-34; 2013.
Disclaimer
The material contained in this publication is comment of a general nature only and is not and nor is it intended to be advice on any specific technical or professional matter. In that the effectiveness or accuracy of any technical or professional advice depends upon the particular circumstances of each case, neither the AWRI nor any individual author accepts any responsibility whatsoever for any acts or omissions resulting from reliance upon the content of any articles. Before acting on the basis of any material contained in this publication, we recommend that you consult appropriate technical/professional advisers.
Grant ensures grape and wine producers will be climate change ready
11 April 2013 >The Australian Wine Research Institute (AWRI) was successful in securing a prestigious grant announced by Senator Joe Ludwig, Minister for Agriculture, Fisheries and Forestry, as part of the first assessment phase of the Carbon Farming Futures Extension and Outreach Program.
The AWRI’s Managing Director, Dr Dan Johnson, said, “This is a significant win for grapegrowers and winemakers in Australia. The securing of this grant enables the latest relevant research undertaken by a vast range of agencies on climate adaptability to be packaged and fast-tracked to grape and wine producers, nationally.”
Dr Mardi Longbottom, AWRI Viticulturist and the person responsible for driving the grant application said, “With this grant, the AWRI is able to deliver a targeted program of climate adaptability information to grape and wine producers in Australia. This highly competitive grant was awarded to the AWRI based on its organisational capacity and proven capability in this area.”
“The grant will enable dissemination of current technical information about greenhouse gas emissions, carbon storage and the Carbon Farming Initiative to stakeholders of the Australian grape and wine sectors and support them to achieve best management practice,” Dr Longbottom said.
Under the first assessment phase of the Australian Government’s Carbon Farming Futures Extension and Outreach Program, the Government will invest in 24 projects valued at $21.3 million. The funding awarded to the AWRI was $750,484 (ex GST).
“We are delighted that the Australian government has recognised the AWRI’s long standing ability to effectively extend information to grapegrowers and winemakers around this country,” Dr Johnson said “and significantly, with this grant, that grape and wine producers will be in a better position to adapt to climate adaptability issues now and in the future.”
For further information contact Rae Blair, AWRI Communication Manager on 0417 810 737 or email: rae.blair@awri.com.au
Timely reminder about slow sluggish and stuck fermentations
27 March 2013 >Vintage 2013 will be remembered for one of the earliest and quickest vintages in recent times. With hot days followed by warm nights, grape sugar levels increased rapidly, culminating in a shorter vintage. With little to no rain in many regions since October 2012, berry nutrient content, especially YAN, is lower than recent vintages, due to reduced soil microbial activity. One of the challenges of a quick vintage can be vintage compression, and it is during these vintages that fermentation management becomes critical. A slow, sluggish or stuck ferment is not something that a winemaker needs or wants to deal with at any time, let alone in a vintage where compression sees logistical challenges such as tank space shortage.
Recent calls to the AWRI’s Winemaking and Extension Services team regarding slow and sluggish fermentations are a timely reminder about the importance of a number of critical factors that are essential in completing fermentations to dryness.
How do you know your ferment is slowing down or stuck? The best way is to monitor the fermentation twice daily for Baume or Brix, and temperature, and to plot this as a fermentation curve (a graph template is available for Australian winemaker use via password on the AWRI website). Graphing these measurements will quickly help identify when ferments begin to slow down, well before it has stopped, so that proactive action can be taken. The fermentation curves can also be used to establish if temperatures are becoming too cool or too warm for the ferment.
If the ferment is slowing down:
- Try warming the ferment up if too cold, or cooling down if it’s getting hot. Yeast like the temperature to be kept relatively stable and, in general, do not function well at temperatures >32°C for reds or <15°C for whites.
- If a natural ferment is slowing down, or a difficult ferment is suspected, then it is best to use an inoculated yeast.
- If the yeast are not that active, or are settling to the bottom of the tank, try some agitation during the initial stage of the ferment; check for budding and/or viability by vital (e.g. methylene blue) staining.
- Aerating once fermentation has started can also help the yeast build strong cell walls for ethanol tolerance to prevent the ferment becoming stuck; there is no risk of oxidising the wine while yeast are active. Aeration is a powerful fermentation stimulant when used correctly.
- If the ferment is slow from the outset, make sure the ferment isn’t slowing due to any fermentation inhibitors including:
- high sulfite concentrations in the must;
- high volatile acidity from native microorganism growth/check for high bacteria count;
- high Baume/Brix content. Some yeast are not tolerant to excessive sugar levels. Correspondingly some yeast don’t cope well in ethanol concentrations >15%;
- agrochemical residues. Grapes harvested within withholding periods can contain some metals, sulfur or other compounds that can stress the fermentation yeast;
- chlorine from water used during yeast hydration; and
- very low pH (typically early harvest whites); some yeast cannot tolerate pH of 3.0 or less, especially when sulfite is present.
For some inhibitors such as high sulfite, a sacrificial yeast addition, or inoculation at twice the usual inoculum can be successful. Ensure the yeast have been strongly aerated to ensure aldehyde production which binds the excessive sulfite.
- If the ferment is slow, or starting to produce sulfides, then nutrients might be an issue; particularly in highly clarified juice, or wines with some native microorganism growth. Measure the yeast assimilable nitrogen (YAN) level and make an addition if in the early stages of fermentation. If DAP doesn’t prevent sulfides, other nutrients such as vitamins or complex nutrients (e.g. inactive yeast products) can be tried. If sulfides persist, it might be coming from agrochemicals such as elemental sulfur.
- Addition of yeast hulls, fresh yeast lees from a recently finished ferment, or addition to an active fermentation can help a struggling ferment go through to dryness.
- Re-inoculate a slow ferment using strong fermenting and alcohol tolerant yeast.
- If the re-inoculation is not successful then try the re-inoculation using a culture or scale-up (step-wise acclimatisation) restart procedure (available on the AWRI website).
- If all else fails, call the AWRI’s Winemaking Services help desk (08 8313 6600).
The AWRI in conjunction with the GWRDC has recently advised winemakers of successful fermentation strategies pre-vintage which can be accessed here:
http://www.gwrdc.com.au/wp-content/uploads/2013/02/INenews-Feb-2013-Wine-processing.pdf
Further information and procedures for managing stuck or sluggish fermentations can be easily accessed via the following links:
Procedure to restart a stuck malolactic fermentation
Malolactic fermentation information pack
Further assistance
Should you require further assistance, please call the AWRI’s Winemaking and Extension Services team on 08 8313 6600 or email: winemakingservices@awri.com.au.
Register for these industry events before 5 April to save
>Do you work in the wine industry? These events are for you. With Easter upon us and many people busy with Vintage, this is a reminder not to miss out on your early registration discount!
15th Australian Wine Industry Technical Conference: 13-18 July, 2013 Sydney NSW
Why should you attend?
Held every three years, the 15AWITC will be held this July in Sydney. An extensive program on offer means there is something for everyone who works with grapes and wine.
24 Australian and 15 international experts will cover all aspects of grape and wine production from the vineyard to consumers. Two additional ‘Fresh Research’ sessions will be held with presentations from selected abstracts of the technical posters, which will be on display throughout the event. 44 workshops on viticulture, winemaking and business will be an excellent way to learn more deeply about relevant topics. WineTech 2013 – exhibits from international and local suppliers – a ‘must-visit’ for anyone interested in the latest technology and services to support your business.
This is the largest gathering of grape and wine professionals in Australia and is an excellent opportunity to catch up with colleagues and to network with industry members from around the world. Register before 5 April to take advantage of the discounted registration fee.
WineHealth 2013: 18-21 July, 2013 Sydney NSW
Why should you attend?
Make the most of your time in Sydney and be part of the discussion on wine’s impact in society and on health by joining delegates at the international forum WineHealth 2013. This event brings together world experts for a stimulating exchange of scientific information and ideas on the impacts of wine consumption on human health, and to explore the effect of wine as a unique alcoholic beverage.
These exchanges will contribute to the evidence base for public policy setting, provide direction for new research efforts into the health effects of wine, and offer opportunities for international collaborations. Register before 5 April to take advantage of the discounted registration fee.
The Australian Wine Research Institute is involved in the planning and staging of both of these events with strong input from industry members throughout Australia – so you can be assured of the quality and value. The 15th AWITC is co-presented by the Australian Society of Viticulture and Oenology.
eNews – March 2013
5 March 2013 >The perfect yeast?
Found a fabulous fermentation?
Health and nutrition claims no longer on the label
Share what you know at Australia’s largest technical event
Events not to be missed in 2013: registration now open
Finalists in women’s R&D State award in grape and wine
Recent literature
The perfect yeast?
Finding it hard to match the perfect yeast to your grapes? Are you confident of the flavour profile you’ll get from the fermentation? What about the mouth-feel and texture of the wine? Here are the AWRI’s top 5 tips to achieve fermentation reliability and optimal flavour characteristics from yeast.
A winemaker‘s KPI is to efficiently produce the best possible wine from a given batch(es) of grapes, which is promoted by a thoughtful choice of yeast. The yeast strain chosen not only impacts on reliability of fermentation but also modulates the wine’s flavour profile, especially aroma, flavour in-mouth and texture. The large range of commercial yeasts provides winemakers with considerable flexibility in choosing the most suitable strain to match must composition and required wine chemical and flavour specifications. Here, the AWRI focuses on yeast properties most important for conventionally inoculated red and white dry wine fermentations.
Before choosing a strain it is important to have a clear description of the wine’s flavour profile and style. Grape maturity at harvest is a key factor which, together with yeast choice, strongly impacts on ethanol, pH and acidity, phenolics profile (colour and texture) and grape and yeast derived flavours. Yeast can be chosen which greatly augment varietal characters, such as fruity or tropical aromas, or tannin extraction, or, on the other hand, some strains can help mask undesirable flavours, such as ‘green’ flavour.
Winemakers have very little restriction on the choice of yeast when fermenting musts with well-balanced chemical and nutrient profiles, that is, those which require minimal intervention through to finished wine. In this case, choice can focus on strains which augment the winery’s varietal style. In all other cases, a number of criteria should be considered to ensure optimisation of fermentation and flavour. However, an important point to remember is not to dramatically change winery practices without first trialling their efficacy over several vintages.
Fermentation reliability
- Fermentation reliability – strain tolerance to ethanol stress: grape maturity has the greatest impact on fermentation reliability since yeast vary in tolerance to ethanol. This property is most evident in highly clarified musts and least in high solids ferments. It should be remembered that many commercial strains have been selected in Europe or elsewhere in which must composition varies greatly from those here, such as lower sugar and higher nitrogen and acidity, meaning that performance can be compromised in Australian juices. Rehydration and fermentation nutrients can increase fermentation robustness but diammonium phosphate (DAP) is important for ameliorating low yeast assimilable nitrogen (YAN) juices and an aeration step can greatly enhance fermentation and reduce residual sugar. Whereas many complex yeast nutrient products can modulate aroma profile, few contain significant YAN necessary to off-set nitrogen deficiency.
- Yeast sulfite and pH tolerance: research in progress at the AWRI (Schmidt 2012-13) has shown that some strains are hyper-sensitive to SO2 in combination with low pH, especially in highly clarified musts, which have low potassium content. This fact is gaining importance with the current wine style trend towards earlier harvest fruit. Furthermore, higher and more effective SO2 additions lower the risk of nutrient competition from indigenous yeasts (such as when delays in transport or processing occur) and incomplete fermentations from spoilage bacteria, especially with physically damaged (e.g. bird, split, heat) or fungal infected fruit. Effective SO2 use enhances Saccharomyces fermentation dominance, and hence an ability to impart strain-specific characteristics. However, care should be taken with non-Saccharomyces yeast which have lower SO2 tolerance.
- Flavour enhancing yeasts: in general, the yeast strain can either have a neutral impact on wine flavour profile, produce strong esters or can enhance varietal character. Grapes that lack varietal distinction can benefit from moderate to high fruity ester production, especially for quick-to-market wines, whereas some varieties, e.g. Sauvignon Blanc, and rosé style can benefit from varietal aroma enhancing strains. Some strains can augment the phenolics profile, such as in Pinot Noir. Some strains can build aroma complexity, such as hybrid, non-Saccharomyces cerevisiae (e.g. S. bayanus) or non-Saccharomyces strains (e.g. T. delbrueckii, Kl. thermotolerans) and some strains can help mask undesirable flavours, such as ‘green’ (e.g. some Sacchromyces hybrids, S. bayanus) (Eglinton et al. 2005, Bellon et al. 2007).
- Off-flavours, notably hydrogen sulfide and wine ‘reduction’: For musts prepared from vineyards which have a history of producing reductive wines, especially for those in which nutrient (e.g. DAP or complex/inactivated yeast products) addition or aeration during fermentation is not successful, can benefit from low/nil H2S-producing strains developed by the AWRI. These strains might lower the requirement for fining, such as with copper.
- MLF incompatibility and off-flavours: the phenomenon of MLF-unfriendly fermentation yeast is now well recognised and is considered a key factor in increasing the risk of wine spoilage, especially Brett, and spoilage bacteria (mousy off-flavour, biogenic amines) during the prolonged onset of MLF. When such delays, which are not related to well-known inhibitory factors (e.g. inappropriate pH, SO2, temperature and/or alcohol), have been experienced in the past, yeast-ML bacteria compatibility should be strongly considered.
Flavour characteristics
Found a fabulous fermentation?
When the stars and moons all align and you’ve created a cracker fermentation, wouldn’t it be great if you could repeat it again next year? Help is at hand. The AWRI can help you to repeat that fermentation by isolating the related yeast or bacteria and storing it for future use.
The AWRI can identify the yeast responsible for that extraordinary fermentation. Or, if there are interesting sensory properties in your wine, the AWRI can help find which yeast and/or bacteria were responsible. Perhaps your MLF went through quickly, or progressed well at a very low temperature, or in harsh wine conditions.
The AWRI Wine Microorganism Culture Collection team can help you. The AWRI can isolate and identify the yeast and bacteria and and can store them for you to use again.
Contact Jane McCarthy or Eveline Bartowsky on telephone 08 8313 6600 or by email.
Health and nutrition claims no longer on the label
The new Standard 1.2.7 – Nutrition, Health and Related Claims in the Australia New Zealand Food Standards Code was gazetted on 18 January 2013. There is a three year transition period for Standard 1.2.7 commencing 18 January 2013 during which time winemakers can use either the provisions in Standard 1.1A.2 – Transitional Standard – Health Claims or the new Standard 1.2.7. Winemakers cannot use a combination of the old and new provisions. There are no stock-in-trade provisions, so after 18 January 2016, all wine being sold will need to comply with the provisions of the new Standard 1.2.7.
Standard 1.2.7 clearly states that alcoholic beverages such as wine are not permitted to make either a nutrition content claim (except about energy or carbohydrate content) or a health claim on the label of the wine bottle or in product advertising. An example is that winemakers will no longer be able to include a measurement of the phenolic compounds, resveratrol, on the wine label, even as part of a nutrition panel. Should a winemaker make a nutrition content claim about energy or carbohydrate content, then a nutrition information panel (NIP) including all mandatory elements of the NIP will need to be provided on the label (refer to Standard 1.2.8 – Nutrition Information Requirements).
Provisions for the declaration of alcohol content on labels given in Standard 2.7.1 – Labelling of Alcoholic Beverages and Food Containing Alcohol, remain unchanged.
Standard 1.2.7 is available on the ComLaw website from the following link on the FSANZ website http://www.foodstandards.gov.au/foodstandards/foodstandardscode.cfm.
Standard 1.2.7 will be discussed in workshop W36 Winemaking, composition and labelling – what you need to know in the international arena at the Australian Wine industry Technical Conference on Tuesday, 26 July 2013 in Sydney. Further information can also be obtained from the FSANZ website at http://www.foodstandards.gov.au/consumerinformation/nutritionhealthandrelatedclaims/.
Extract from Standard 1.2.7
“Editorial Note:
Standard 1.1A.2 is a transitional standard that operates concurrently with this Standard 1.2.7 for a period of three years. During the three-year period Standard 1.1A.2 operates unchanged by this Standard and related variations made by the Food Standards (Proposal P293 – Nutrition, Health & Related Claims – Consequential) Variation. A supplier can rely on this Standard or Standard 1.1A.2, but not both. At the end of the three-year period, Standard 1.1A.2 will cease to operate. There is no stock-in-trade period at the end of the three-year period.”
Share what you know at Australia’s largest technical event
Presenting a poster at the 15th Australian Wine Industry Technical Conference is a great way to get your research work in front of Australia’s grape and wine producers. Poster abstracts are currently being accepted and must be sent by 5 April 2013.
Submit your poster abstract for a chance to win a prize or be selected to present your research in a ‘Fresh Research’ session at the Sydney Convention and Exhibition Centre, Darling Harbour. Posters will be displayed 14-17 July 2013. Online abstract submission and further information is available on the AWITC website by clicking here, or from Dr Eveline Bartowsky, Poster Coordinator. Poster abstract submissions close on Friday 5 April 2013 – don’t miss out on the opportunity to highlight your latest grape and wine research and outcomes to national and international industry members.
The 15th Australian Wine Industry Technical Conference will be held 13-18 July 2013 at the Sydney Convention Centre and further information can be obtained by clicking here.
Events not to be missed in 2013: registration now open
Registrations are now open to two international conferences for the Australian grape and wine industry (to be held in Sydney, July 2013). Register early to gain the benefit of discounted registration fees. Click here to register for the 15th Australian Wine Industry Technical Conference (13-18 July 2013 at the Sydney Convention Centre) or click here to download the registration form for the WineHealth 2013 conference (18-21 July 2013 at the Sydney Convention Centre).
The 15th Australian Wine Industry Technical Conference is held every three years and is the premier technical conference and trade exhibition held for industry members. The program covers all aspects of the grape and wine business and provides a valuable opportunity for sharing of information and networking with industry colleagues. More than 1,000 national and international delegates are expected and will be held 13-18 July at the Sydney Convention Centre. Complementing the program is an extensive technical poster display and 44 workshops. Workshops will be held from Saturday, 13 July through to Thursday, 18 July and places will be allocated on a first-come-first-served basis. Click here for further details of workshops on offer. Poster abstracts can be submitted (here) up to 5 April – so if you are undertaking work that the industry should know about, don’t miss this opportunity. Visit the AWITC website to see full details of the event program.
WineHealth 2013 continues the series of scientific international conferences discussing the complex interaction of wine and health (which have been held previously in Italy, USA, Chile, South Africa and France over the past 17 years). In 2013, the next conference will be held in Sydney from 18-21 July at the Sydney Convention Centre and is open to anyone interested in this topic. Information on the program and speakers are on the website (http://www.winehealth.com.au).
Finalists in women’s R&D State award in grape and wine
The AWRI’s Viticulturist, Mardi Longbottom and Cape Jaffa Wines winemaker, Anna Hooper have been selected from a strong field of entrants as South Australian finalists for the 2013 RIRDC Rural Women’s Award. The award supports women with leadership potential who have the desire and commitment to make a greater contribution to their industries and communities.
Now in its 16th year, the award provides rural women with the opportunity to realise their visions for primary industries and to meet a network of equally passionate and innovative peers.
South Australian Minister for Agriculture, Regional Development and the Status of Women, Gail Gago, said the two finalists were clearly very passionate about their chosen fields.
“These two women have a passion to share their knowledge and experience with other women in their industries,” Ms Gago said. “In turn they are also very keen to meet more women from across all primary industries, to learn and develop creative ways of doing business or undertaking research.
“They understand that it takes innovative ideas and courage to put them into practice to achieve success.”
The winner will receive a $10,000 bursary provided by the Rural Industries Research and Development Corporation (RIRDC) to implement a vision for their industry as well as a one week residential Australian Institute of Company Directors course, to enhance their leadership capabilities.
The 2013 SA RIRDC Rural Woman of the Year will be announced by Minister Gago on Wednesday 6 March 2013 at the Adelaide Pavilion.
The award is jointly sponsored by PIRSA, Westpac, ABC Radio and Fairfax Agricultural Media.
The 2013 RIRDC Rural Women’s Award finalists:
Dr Mardi Longbottom is a Viticulturist at The Australian Wine Research Insitute. She grew up on a farm in Padthaway; is a grape grower, viticulturist and viticultural consultant with 21 years’ experience in vineyard management, technical viticulture research, education and extension.
Mardi has enjoyed working with women across all areas of the grape and wine sector, and is passionate about sharing her knowledge and experience to stimulate and encourage the next generation of female viticulturists.
Mardi’s goal is to showcase positive female role models who are actively engaged in a diverse range of careers in the viticulture industry; and promote viticulture as an opportunity for varied and exciting career pathways to secondary and tertiary students.
Anna Hooper is a winemaker at Cape Jaffa Wines in the Mount Benson wine region near Robe. Dedicated to science and the environment, Anna has been instrumental in developing one of the first certified biodynamic wine ranges in South Australia.
Anna’s vision is to see the Australian Wine Industry recognised as a world leader in
environmental performance made up of environmentally savvy businesses valuing and investing in long term sustainability; and deriving associated benefits from their efforts.
Recent literature
John Fornachon Memorial Library at the AWRI delivers journal articles and loans books to Australian grapegrowers and winemakers. Books can be searched and requested via the Library catalogue – or you can email the AWRI with your request.
Recent AWRI staff publications
Bindon, K., Varela, C., Kennedy, J., Holt, H., Herderich, M. Relationships between harvest time and wine composition in Vitis vinifera L. cv. Cabernet Sauvignon 1. Grape and wine chemistry. Food Chem. 138 (2-3): 1696-1705; 2013.
Connew, S., Riggs, I. The show must go on. Wine Viti. J. 27 (6): 70, 72; 2012.
Costello, P.J., Siebert, T.E., Solomon, M.R., Bartowsky, E.J. Synthesis of fruity ethyl esters by acyl coenzyme A: alcohol acyltransferase and reverse esterase activities in Oenococcus oeni and Lactobacillus plantarum. J. Appl. Microbiol. doi:10.1111/jam.12098: 1-10; 2012.
Cowey, G. AWRI workshop wraps up packaging problems. Aust. N.Z. Grapegrower Winemaker (588): 71-72; 2013.
Dry, P. Nero d’Avola. Wine Viti. J. 27 (6): p.68; 2012.
Krstic, M.P. Spray application in vineyards – still the key to successful pest and disease management. Aust. N.Z. Grapegrower Winemaker (587): 28; 2012.
Longbottom, M. Ask the AWRI: What are the benefits of nutritional analysis and how do I get the most from the results? Aust. N.Z. Grapegrower Winemaker (587): 49; 2012.
McRae, J.M., Schulkin, A., Kassara, S., Holt, H.E., Smith, P.A. Sensory properties of wine tannin fractions: Implications for in-mouth sensory properties. J. Agric. Food Chem. 61 (3): 719-727; 2013.
Scrimgeour, N., Cynkar, W., Wilkes, E. Non-invasive spectroscopic screening: a new approach to assessing damaged wines. Aust. N.Z. Grapegrower Winemaker (582): 77-78; 2012.
Simos, C.A., Coulter, A.D., Henschke, P.A., Holdstock, M.G., Cowey, G.D., Essling, M. Managing diseased fruit. In Making the best out of difficult vintages: Managing sub-optimal fruit in the winery: proceedings of an ASVO oenology seminar held on 22 November, 2011:. 4 p.; 2013.
Ugliano, M., Henshke, P.A., Waters, EJ. Fermentation and post-fermentation factors affecting odor-active sulfur compounds during wine bottle storage. Qian, M., Shellhammer T.H. (Eds) Flavor chemistry of wine and other alcoholic beverages. ACS Symposium Series, Vol. 1104 189-200; 2012.
Disclaimer
The material contained in this publication is comment of a general nature only and is not and nor is it intended to be advice on any specific technical or professional matter. In that the effectiveness or accuracy of any technical or professional advice depends upon the particular circumstances of each case, neither the AWRI nor any individual author accepts any responsibility whatsoever for any acts or omissions resulting from reliance upon the content of any articles. Before acting on the basis of any material contained in this publication, we recommend that you consult appropriate technical/professional advisers.
Vale Dr Bryce Rankine AM
1 March 2013 >It is with sadness that the AWRI records the passing of Dr Bryce Rankine on 26 February 2013.
Many in the industry would know Bryce and be aware of the enormous contribution he made to wine science and the modern Australian wine industry.
After working in the oenological investigations section of the CSIRO at the Waite Agricultural Research Institute, Bryce joined the AWRI with Dr John Fornachon just after its establishment in 1955. His initial work at the AWRI was on yeasts, fermentation, ethanol production, lead content and other metals in Australian wines, treating wine with ion-exchange resins and preventing potassium bitartrate deposition in wine.
By the time Bryce left the AWRI as its Principal Research Scientist, he had published more than 250 papers in trade publications, peer reviewed papers, conference/symposium/seminar papers. He published in peer-reviewed journals such as: American Journal of Enology and Viticulture; Annales de Technologie Agricole; Australian Journal of Applied Science; Connaissance de la Vigne et du Vin; Food Technology in Australia; Mitteilungen Klosterneuburg Rebe und Wein Obstbau und Früchteverwertung; and Vitis. He was also a regular contributor to many industry journals.
During his 22-year tenure at the AWRI, Bryce was extremely active in visiting wineries and regions to extend his work to help winemakers overcome production issues, and he commenced the AWRI’s valuable ‘help desk’ service, which today services over 1,000 calls per year. He also travelled overseas presenting at conferences and bringing back to Australia information about production practices in other countries, preparing the following papers for the Council of The Australian Wine Research Institute: Observations on wine making and wine research in France, Germany, Switzerland and California (1967); and The South African wine industry – a technical appraisal (1971).
By the time that Bryce accepted the position of Head of School of Viticulture and Oenology at Roseworthy Agricultural College in 1978, he was arguably the most prominent wine scientist in Australia and also well-known internationally. In that position, he provided strong leadership and successfully fought for resources at a time when there was strong competition.
He presided over the time when the Diploma of Oenology changed to a Bachelor of Applied Science (Oen) and the greater emphasis on basic sciences that was a requirement of that change. Also the Graduate Diploma in Wine was introduced in 1980 and many Science graduates were able to enter the wine industry via this pathway.
The international reputation of the oenology program at Roseworthy was significantly enhanced during his tenure, partly due to his extensive network of wine scientists and the fact that he was an invited speaker at many overseas conferences. Also, by using his contacts at the highest levels within the wine industry, he was able to gain much local support for the program. He encouraged greater emphasis of the viticulture component of the oenology degree and the development of the degree in viticulture which had its first intake of students soon after his retirement.
Bryce, along with CSIRO’s Dr Peter May and The University of Adelaide’s Dr Bryan Coombe, donated images relevant to more than 50 years of grape and wine science to establish an online image collection available to current and future generations of industry members (managed by the AWRI).
A prolific writer, Bryce authored the following seminal texts on wine science:
- Making good wine: first published in 1989. Revised editions were published in 1998 and 2004. A Spanish edition was also published in 1989. This text remains on the syllabus of The University of Adelaide.
- Wines and wineries of the Barossa Valley: published in 1971.
- Tasting and enjoying wine: first published in 1990 and reprinted in 1999.
- Sparkling wines: co-authored with Armstrong and Linton published in 1994.
- History of the Australian wine industry – evolution of the modern Australian wine industry: published in 1996.
- Refrigeration for winemakers: co-authored with White and Adamson, first published in 1989 and revised in 1998.
- Cooperage for winemakers: co-authored with Schahinger, first published in 1992 and revised in 2005.
- SO2 analysis: In 1927, the Monier-Williams ‘aspiration’ method for SO2 analysis was published; this method was improved by Thompson and Toy in 1945 and further enhanced by Rankine in 1962 and then by Rankine and Pocock in 1970.
Through his outstanding career, Dr Bryce Rankine received the following recognitions of his contribution to science and the Australian wine industry:
- Fellow, Royal Australian Chemical Institute (1969)
- DSc, University of Stellenbosch (1971)
- American Society of Enology and Viticulture Outstanding paper of the year (1971), first Australian member of the editorial panel of their Journal, Honorary Life Member (1993)
- Fellow, Australian Institute Food Science and Technology (1971), Order of Merit (1973), President (1982-4)
- Member of the Confrerie des Chevaliers du Tastevin of Burgundy (1973)
- Fellow, Australian Academy of Technological Sciences and Engineering (1976)
- Companion of Barons of the Barossa (1976)
- Member of the Order of Australia (1986)
- Society of Wine Educators USA Award of honour (1987)
- Honorary Life Fellow Australian Society of Microbiology (1987)
- Australian Society of Wine Educators Founder and Executive Director (1990-1995), Life Fellow (1995)
- Recipient of the Hartnett Medal from the Royal Society of the Encouragement of Arts, Manufacturing and Commerce, London, for contributions to the development of the Australian wine industry
- Recipient of the Maurice O’Shea Award (1998)
- Centenary Medal for service to Australian society in science and technology (2001)
The funeral for Dr Bryce Rankine AM will be held on Monday, 4 March at 3.30 pm in the Chapel of Berry’s Funeral Home, 204 Magill Road, Norwood, South Australia.
Technical Review: February 2013 issue is now online
12 February 2013 >The February 2013 issue of Technical Review is now available for viewing online and for downloading. Access is available only to Australian winemakers and grapegrowers who pay the Wine Grapes or Grape Research levies.
The new online Technical Review allows you to browse the list of the latest articles on grape and wine production by keyword, view article summaries and order journal articles from the AWRI Library.
To access the issue, click here.
Management strategies to assist with the recent hot weather conditions and potential for smoke taint
10 January 2013 >The extreme hot weather conditions, which were experienced since the first week of January 2013 across many parts Australia, has led to a number of bush fire events, conditions of which could also possibly lead to increased incidence of smoke exposure in vineyards.
The presence of smoke taint in fruit is governed by a number of factors including proximity and type of fire, intensity, duration of smoke cover, prevailing wind and weather conditions etc.
The timing of smoke exposure to grapevines is also important; there is low sensitivity to smoke uptake in the growth period to flowering, low to moderate risk through to veraison, and beyond veraison through to harvest, grapevines can be highly susceptible.
Currently, it has been reported that in many of the cooler regions, vine growth stage is between bunch closure and veraison. Whilst this may be in the lower risk category at the moment, the situation may change if fire and smoke events continue.
The AWRI recommends grapegrowers and winemakers follow the below testing regime to ensure grapes are free from smoke taint and remain fit for purpose:
- If your region has experienced a smoke event, wait until ripening has proceeded beyond veraison before testing for smoke taint.
- There is considerable variation across a vineyard, so follow a sampling regime that takes into account topographical features of the vineyard and follow the same sampling regime when carrying out repeated sampling.
- Small lot fermentation is highly recommended in assessing potential to produce smoke taint in wine. The AWRI has developed a basic fermentation protocol which is available on the AWRI website.
- Analytical support is available and this is also summarised on the AWRI website (click here for analysis FAQ)
More detailed information is available via the following link
https://www.awri.com.au/information_services/current-topics/smoke-taint/
Most grapegrowing regions recorded spring rainfall well below average; it is a timely reminder to ensure that water status is maintained.
The effect of extreme heat on grapevines depends on the timing of the heat event relative to the grapevine growth stage. Flowers are highly susceptible and poor fruitset may occur from a heatwave during flowering. After veraison (as grapes soften) grapes become more prone to shrivel or sunburn. Dark coloured grapes directly exposed to the sun may get much hotter (up to 15°C) than the surrounding air temperature.
Irrigation management is critical before, during and after a heat event. Ideally, water should be applied during the season to establish a canopy that can protect bunches from direct exposure. Before the heat arrives, aim to fill the rootzone to field capacity if possible to enable the cooling that occurs when leaves transpire. Postpone any canopy manipulation that may increase bunch/berry exposure. During the heatwave, maintain soil moisture and if using overhead irrigation, apply at night to avoid foliage burn. Also, wind events during heatwaves can result in the canopy rolling and over-exposing the fruit. Look to implement management strategies which can reduce the likelihood of this occurring using foliage wires, etc. After the heatwave, irrigate to replace lost soil moisture and decrease soil temperature. Monitor for pests and disease that may exploit damaged berries.
More detailed information can be found in the GWRDC Innovators Network factsheet: Managing grapevines during heatwaves: http://www.gwrdc.com.au/wp-content/uploads/2012/09/2012-01-FS-Managing-Grapevines-Heatwaves.pdf.
Further assistance
Should you require further assistance, please call the AWRI’s Viticulture, Winemaking and Extension Services team on 08 8313 6600 or contact the AWRI by email.