The Australian Wine Research Institute Blog

eNews – March 2014

4 March 2014 >

Important regulatory changes for wine exported to China
Vintage 2014 – Half time report
Significant interest in low alcohol yeast
Closure benchmarking trial set to sparkle
Which paints cause taints?
Did you miss a webinar?
Two new fact sheets shed light on tannin measurement
Louisa Rose to chair the AWRI Board
Australian Wine Industry Technical Conference update
2006-2013 Final Report available online
Recent literature

Important regulatory changes for wine exported to China

On 27 February, Wine Australia released a warning to wine exporters regarding the increased scrutiny of manganese, iron and copper levels in wine by Chinese authorities. Maximum regulatory levels now being imposed by Chinese authorities are 2 mg/L for manganese, 1 mg/L for copper and 8 mg/L for iron. It is therefore recommended that all wine intended for export to China should undergo analysis to confirm that it complies with these limits. Excessive levels of copper and iron in wine have been shown to decrease the shelf life of wines and in some cases promote the formation of unpleasant sulfides, while manganese has a limited impact on wine chemistry. For all three metals there are no health concerns at these levels.

Analysis of these metals is available through reputable laboratories including AWRI Commercial Services For more information about manganese and other metals please contact winemakingservices@awri.com.au.

Vintage 2014 – Half time report

Vintage is well underway in most regions now, and so far it has been one influenced by extreme weather conditions, especially in south-eastern Australia. Heatwaves and record breaking daytime temperatures, followed by 100 mm of rain in some locations, have been experienced in the first part of the 2014 vintage. Smoke taint has been by far the biggest concern this vintage and represents nearly 25% of the vintage-related calls received by the AWRI’s helpdesk so far.

As reported previously (eNews November 2013) most wine-grape varieties are highly sensitive to smoke taint from seven days post-veraison to harvest. This means if a vineyard has been exposed to smoke sometime after the point when the berries are pea size, the recommendation is to sample the vineyard two weeks prior to the harvest date and conduct a small-lot fermentation. The wine resulting from this fermentation can be subjected to sensory assessment and chemical analysis (for both volatile phenols and their glycoside precursors) in order to gauge the potential risk of any smoke taint that might arise from the smoke exposure. The AWRI’s website provides links to a range of resources on smoke taint as well as further information about the susceptibility of grape varieties. Results from a limited number of small-lot ferment samples analysed this vintage have shown that when volatile phenol results are low, glycoside precursor levels can still be above those seen in a previous study of baseline concentrations. It is therefore recommended that all analytical data (i.e. volatile phenols and their glycoside precursors) be compared with sensory results to give a true picture of any effects due to smoke.

At the other end of the weather spectrum, there have been many discussions between vineyard owners and winemakers regarding the effects of the heavy rain that hit south-eastern Australia in the second week of February. If berries have split, this increases the potential for disease, including Botrytis cinerea. Wines made from Botrytis-affected grapes may contain laccase, an enzyme which is capable of causing serious oxidative damage. Testing for laccase is strongly advised. More information on managing Botrytis-affected fruit can be found in this fact sheet.

Stuck fermentations (both primary and secondary) can be a winemaker’s worst nightmare, with a number of flow-on effects including holding up fermentation vessels and compromising wine quality. In 2013 the AWRI’s helpdesk received a large volume of calls relating to these types of problems. This eBulletin is worth revisiting for its tips on how to prevent fermentation problems this vintage.

Significant interest in low alcohol yeast

Since the AWRI’s publication of a peer-reviewed article on the capacity of Metschnikowia pulcherrima AWRI1149 to produce wines with lower alcohol when used in sequential inoculation with a wine yeast strain, there has been considerable industry interest in accessing AWRI1149.

To the best of the AWRI’s knowledge, this yeast strain is not currently commercially available; however, several companies have expressed interest in commercialising it. The AWRI will be conducting its own pilot-scale trial with AWRI1149 this vintage.

One of the interesting findings of the research was that of the five strains of M. pulcherrima tested, only one was found suitable to produce lower alcohol wines via sequential inoculation. Performance in sequential inoculations was highly strain dependent. Winemakers should therefore not assume that if one strain of M. pulcherrima is commercially available that it will necessarily share the properties of AWRI1149.

To request a copy of the peer-reviewed article, please contact the AWRI’s library on infoservices@awri.com.au. For more information on sequential inoculation or to express interest in being involved in industry trials, please contact Paul Chambers on 08 8313 6600 or paul.chambers@awri.com.au.

Closure benchmarking trial set to sparkle

In 2014, AWRI Commercial Services will be conducting the world’s first large-scale benchmarking trial for sparkling wine closures. The trial will evaluate the impact of a broad range of different closure technologies on a premium bottle-fermented Chardonnay Pinot Noir, and will run for an initial 24-month period.

    The objectives of the trial are to:

  • Quantify key physical chemical and sensory impacts from each closure
  • Compare the shelf-life of sparkling wine under different closures.

A group of local sparkling wine producers and a number of international closure suppliers have committed to the trial, which is expected to start in the next two months. The trial is structured to enable cost effective access to relevant results and there are multiple options available to fit producers’ technical requirements and budgets.

With the growing consumer interest in sparkling wine and the ever increasing number of closure choices available, there has never been a more important time for producers to be confident in the performance and consistency of their sparkling wine closure.

The AWRI has years of evidence demonstrating how closure selection affects the shelf-life and stylistic development of still wines, but currently there is very limited information available for sparkling wines. This trial will provide a rigorous independent assessment of closure performance to give wine producers and closure suppliers the information they need to make informed decisions for their products.

A targeted industry survey has identified the top six closures that are of most interest for Australian sparkling wine producers. These six closures form the core part of the trial and include traditional, technical and alternative closure technologies. Additional closures are also being sponsored for inclusion by closure suppliers.

The analytical testing schedule includes basic wine attributes, colour development, sulfur-containing compounds, carbon dioxide (CO2) retention, oxygen transmission rate (OTR), physical integrity and descriptive sensory analysis.

In addition, the AWRI intends to hold a number of tasting workshops in selected regions to showcase the wine’s development under the different closures. This will give small and medium wine producers the opportunity to experience the sensory impact of closure choice firsthand and will provide an overview of the trends seen throughout the trial.

If you wish to be involved in this trial or would like further information, please contact Neil Scrimgeour on 08 8313 6600 or neil.scrimgeour@awri.com.au.

Which paints cause taints?

Every vintage, the AWRI sees some wines that have been tainted by aromatic hydrocarbons from paints used on grape bins or other winery equipment. Appropriate choice of paint and sufficient curing time can go a long way towards preventing unwanted taints.

Grape bins today are typically made out of stainless-steel or high density polyethylene which can be used without the need for painting or pre-treating before use. However, bins made from non-food grade material or base steel need to be painted periodically, so they can be used in the wine industry. But which paints should you use? The paint must be suitable for contact with food, and recommended for grape bins. The main options are single pack and two pack epoxy; and both have advantages and disadvantages. It is recommended that your choice be guided by consultation with your paint supplier.

Which paints cause taints? If not applied correctly or not given enough time to dry and cure, any paint can cause a taint. Having said that, if the manufacturer’s instructions are followed for application, drying and curing time, the likelihood of a taint is significantly reduced. It is recommended that 7 to 12 days be allowed for single pack and two pack epoxy paints to fully dry and cure before use.
For more information about wine taints, please contact winemakingservices@awri.com.au.

Did you miss a webinar?

Since 2012, the AWRI has hosted more than 35 webinars on topics including: canopy management, hybrid yeast, alternatives to bentonite, rootstocks, oxygen management during winemaking and dealing with frost. If you missed a webinar when it was broadcast, you can still watch it at a time of your choice by accessing the recordings on the AWRI website. Recordings of the 2012 webinars and 2013 webinars are available. You will need to enter your name and email address for access, and you may need to download a small piece of software called a codec to allow the recordings to play on your computer. If you have any difficulties accessing the recordings, please contact Michael Downie on 08 8313 6600 or infoservices@awri.com.au.

Two new fact sheets shed light on tannin measurement

Tannin and colour measurement in grapes and wine can be challenging – and around the world different analytical methods are used. Two new fact sheets (one on grape analysis and one on wine analysis) have recently been added to the AWRI website, explaining how results from the WineCloudTM can be compared to those from other common methods.

There are a number of different methods available for the analysis of colour (anthocyanins) and phenolics in grapes. These methods all use spectroscopic techniques to measure the total anthocyanin and polyphenol content of grape homogenates. However, the extraction media used (pH and ethanol concentration) and the homogenisation processes are different for each method and therefore the extraction efficiency in each case will be different. The preparation method appears to influence all published methods for the determination of colour and phenolics in grapes.

The WineCloudTM incorporates the AWRI’s standard method (Iland et al. 2004) for the measurement of grape anthocyanins and phenolics, and a predictive algorithm based on the methyl cellulose precipitation (MCP) method developed by the AWRI (Dambergs et al. 2012) for the measurement of tannin.

Those wishing to develop a better understanding of the anthocyanin, phenolic and tannin levels in their grapes should be aware of the impact that homogenisation method and extraction medium can have in extracting these components from the grape homogenate.
For more information on tannin measurement for grapes and wine, please contact Neil Scrimgeour on 08 8313 6600 or neil.scrimgeour@awri.com.au.

References

Dambergs, R.G., Mercurio, M.D., Kassara, S., Cozzolino, D., Smith, P.A. Rapid measurement of methyl cellulose precipitable tannins using ultraviolet spectroscopy with chemometrics – application to red wine and inter-laboratory calibration transfer. Appl. Spectrosc. 66 (6): 656-664; 2012.

Iland, P., Bruer, N.; Wilkes, E., Edward, G. Anthocyanins (colour) and total phenolics of grape berries. Chemical Analysis of Grapes and Wine: Techniques and Concepts, 1st ed.; Winetitles: Broadview, Australia, 2004; pp 44.

Louisa Rose to chair the AWRI Board

Yalumba and Hill-Smith Family Vineyards Chief Winemaker Louisa Rose has been elected the fifteenth Chair of the Board of the Australian Wine Research Institute (AWRI).

Known for her work in pioneering Viognier in Australia, Louisa Rose has more than 20 years of wine industry experience and has been Chief Winemaker at Yalumba and Hill-Smith Family Vineyards since 2006. Louisa has been highly awarded for her winemaking including being named Barossa Winemaker of the Year in 1999, International Woman in Wine by the International Wine and Spirit Competition in 2004 and Winemaker of the Year by Gourmet Traveller Wine Magazine in 2008. Louisa is an experienced wine show judge, and has chaired both Perth and Hobart wine shows. She is co-chair of the South Australian Wine Industry Council and a member of the South Australian Agribusiness council.

Louisa holds a Bachelor of Science in Physics and a Bachelor of Applied Science in Oenology. During her time at Yalumba she has been a supportive industry partner for a number of AWRI research projects, particularly in the area of non-conventional yeast.

Louisa takes over from Peter Dawson who has served as a Board member since 2002 and as Chair since 2010. The AWRI Board thanked Peter for his long-standing support of the AWRI and his exceptional contributions as Board member and Chair. A farewell function was held by the Board for Peter in December 2013.

Australian Wine Industry Technical Conference update

The AWITC recently announced that the16th Australian Wine Industry Technical Conference & Trade Exhibition 2016 will be held at the Adelaide Convention Centre, from 23 to 28 July 2016.

The 16th AWITC & TE 2016 will include plenary sessions, workshops, posters, social functions and an extensive trade exhibition.

Significant support for the event has recently been confirmed from two key partners – Primary Industry and Regions SA (PIRSA) and the Adelaide Convention Centre (in association with their industry partners the South Australian Tourism Commission and the Adelaide Convention Bureau).

For more information about the 2016 event, please contact Kate Beames, Conference Manager, on 08 8313 6600 or kate.beames@awitc.com.au.

2006-2013 Final Report available online

At the conclusion of the AWRI’s 2006-2013 investment agreement with the GWRDC, AWRI staff prepared a detailed report of the key outcomes from that 7-year period. This report is now available from the AWRI website.

The report is divided into 13 streams plus an Impact Summary and includes a full list of publications from the investment period.
The outcomes achieved for industry during the period reflect the success of the investment model that was in place – one that combined long-term stability with short-term adaptability and allowed the AWRI to pursue medium-term research and development projects while responding to changing industry conditions.

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

1583 Contreras, A., Hidalgo, C., Henschke, P.A., Chambers, P.J., Curtin, C., Varela, C. Evaluation of non-Saccharomyces yeast for the reduction of alcohol content in wine. Appl. Environ. Microbiol. doi:10.1128/AEM.03780-13; 2013.

1584 Viviers, M.Z., Smith, M.E., Wilkes, E., Smith, P.A. Effects of metals on the evolution of volatile sulfur compounds in wine during bottle storage. Aust. N.Z. Grapegrower Winemaker (600): 49-51; 2014.

1585 Wilkes, E. You’ve got to be a hot shot to hit the moving target of cold stability. Aust. N.Z. Grapegrower Winemaker (600): 43-46; 2014.

1586 Cowey, G. Ask the AWRI: Top tips for a successful yeast culture. Aust. N.Z. Grapegrower Winemaker (600): p. 42; 2014.

1587 Bindon, K.A., Madani, S.H., Pendleton, P., Smith, P.A., Kennedy, J.A. Factors affecting skin tannin extractability in ripening grapes. J. Agric. Food Chem. doi.org/10.1021/jf4050606: 12 p.; 2014.

1588 Dry, P. Malvasia istriana. Wine Viti. J. 29 (1): p. 53; 2014.

1589 Viviers, M., Smith, M., Wilkes, E., Smith, P., Johnson, D. The role of trace metals in wine ‘reduction’. Wine Viti. J. 29 (1): 38-40; 2014.

1590 Francis, L. Des études multidisciplinaires à l’Australian Wine Research Institute. Revue des Oenologues et des Techniques Vitivinicoles et Oenologiques (149 Supp.): p. 9; 2013.

1591 Geffroy, O., Dufourcq, T. Carcenac, D., Siebert, T., Herderich, M. Nouvelles acquisitions sur le caractère poivré. Des vins rouges de Duras de l’AOP Gaillac. Revue des Oenologues et des Techniques Vitivinicoles et Oenologiques (149 Supp.): 49-51; 2013.

1592 Bartowsky, E., Costello, P., Krieger-Weber, S., Silvano, A., Dumont, A., Francis, L., Travis, B. Au-delà de la fermentation malolactique. Évaluation et caracterisation de l’impact sensorial des bactéries oenologiques sur le caractère fruité des vins rouges. Revue des Oenologues et des Techniques Vitivinicoles et Oenologiques (149 Supp.): 61-65; 2013.

1593 Essling, M. Ask the AWRI: Canopy damage from herbicides. Aust. N.Z. Grapegrower Winemaker (601): p. 32; 2014.

1594 Dry, P. Terroir and the topic of wine typicity. Aust. N.Z. Grapegrower Winemaker (601): p. 40; 2014.

1595 McRae, J., Smith, P. Seal the deal on pH, red wine colour and tannin during bottle ageing. Aust. N.Z. Grapegrower Winemaker (601): 51-54; 2014.

1596 Gawel, R., Schulkin, A., Smith, P.A., Waters, E.J. Taste and textural characters of mixtures of caftaric acid and Grape Reaction Product in model wine. Aust. J. Grape Wine Res. 20 (1): 25-30; 2014.

Vineyard sprays – clarifying label directions

24 February 2014 >

Since 2010, label changes have been introduced by the Australian Pesticides and Veterinary Medicines Authority (APVMA) for vineyard spray products, with the aim of reducing the risk of spray drift. Some of the new directions included on labels have caused confusion for vineyard operators. This eBulletin aims to clarify the new label directions, and assist the Australian wine industry in applying best practice spray techniques and record-keeping.

Common label instructions are listed below, with clarifying comments shown in italics.

Spray drift restraints on new labels:

  • DO NOT apply with spray droplets smaller than a MEDIUM spray droplet size category according to nozzle manufacturer specifications that refer to the ASAE S572 Standard or the British Crop Production Council (BCPG) Guideline.

    This is not applicable in orchard/vineyard situations. Labels in future will carry the comment ‘Except when applying with orchard/vineyard airblast equipment’. ‘Airblast equipment’ refers to ground operated equipment used in orchards and vineyards for canopy sprays.

  • DO NOT apply when wind speed is less than 3 or more than 20 kilometres per hour as measured at the application site.

    A minimum speed of 3 km/hr is required because times of no wind (essentially below 3 km/hr) often precede or accompany periods of highly stable air and surface temperature inversion conditions both of which can greatly increase spray drift risk. Moreover, when wind resumes after periods of calm, its direction is not predictable. Spraying only when there is at least some wind ensures that wind direction is known (so that drift onto sensitive areas can be avoided) and greatly reduces the likelihood of surface temperature inversions forming during or shortly after application.

    Further information can be obtained from the APVMA here: http://www.apvma.gov.au/use_safely/docs/spraydrift_op_principles.pdf

  • DO NOT apply in vineyards when the wind speed is less than 3 or more than 20 kilometres per hour as measured 15 metres outside of the vineyard on the upwind side.

    It may not be practical or legal to measure wind speed beyond the vineyard boundary. The intention is that wind speed (and direction) is measured without interference from the vines and upwind of the vineyard. When safe and practical, wind speed should be measured 15 metres upwind.

  • DO NOT direct the spray above vines during airblast applications.

    ‘Airblast’ refers to equipment used for canopy sprays in orchards and vineyards.

  • TURN OFF outward pointing nozzles at row ends and outer rows during airblast applications.

    ‘Airblast’ refers to equipment used for canopy sprays in orchards and vineyards.

  • DO NOT apply during surface temperature inversion conditions at the application site.

    The APVMA factsheet for recognising temperature inversion conditions can be found here: http://www.apvma.gov.au/use_safely/spray_drift/inversions.php

    Further information from the Bureau of Meteorology can be found here: http://www.bom.gov.au/info/leaflets/Pesticide-Spraying.pdf

Additional directions on new labels

New labels also contain instructions about the spray records that must be kept.

Users of this product MUST make an accurate written record of the details of each spray application within 24 hours following application and KEEP this record for a minimum of 2 years. The spray application details that must be recorded are:

  1. date with start and finish times of application;
  2. location address and paddock/s sprayed;
  3. full name of this product;
  4. amount of product used per hectare and number of hectares applied to;
  5. crop/situation and weed/pest;
  6. wind speed and direction during application;

    At a minimum, wind speed and direction should be measured and recorded at the beginning of spraying and again when any change in conditions is observed during spray operations. Wind speed is measured by an anemometer. The measurement should be upwind of any interference or two metres above the canopy. Systems that measure wind speed and direction and relay that information to operators or issue warnings when cut-off levels (i.e. wind speed exceeds 20km/hr) are reached are available but not compulsory.

  7. air temperature and relative humidity during application;

    At a minimum, air temperature and relative humidity should be measured at the beginning of spraying and again if any change in conditions is observed during spray operations.

  8. nozzle brand, type, spray angle, nozzle capacity and spray system pressure measured during application;

    Where applicable, record details about the nozzles used as listed. Spray angle refers to the angle of the spray sheet generated by the nozzle. For example, a flat fan nozzle may have a 110° spray sheet.

  9. name and address of person applying this product. (Additional record details may be required by the state or territory where this product is used.)

Spray record sheet

The AWRI in conjunction with industry has developed a spray diary template and set of terminology for growers who do not have a spray diary provided by a winery or grape purchaser. The diary captures the information listed for points 1-9 above, except for point number 8. Information about nozzles and operating pressures should instead be captured in spray cart calibration records.

Further assistance The AWRI offers a free and confidential help desk service on technical issues, to all Australian grapegrowers and wine producers. Should you require further assistance, please call the AWRI’s help desk on 08 8313 6600 or email: viticulture@awri.com.au.

How should I deal with split fruit and disease pressure as harvest approaches?

18 February 2014 >

Last week many regions across south-eastern Australia experienced heavy rains. These conditions have increased the risk of berry split and fungal disease development.

In the lead up to harvest, the aim is to protect clean fruit and prevent the spread of new and existing fungal infections. A number of agrochemical options are still available; however an effective management strategy should consider the following:

  • Ongoing monitoring
  • Spray coverage
  • Resistance management
  • Time to harvest

Below is an excerpt from the 13/14 ‘Dog Book’ to guide the management of key diseases in the approach to harvest. This is not intended to be an exhaustive list, rather it is based on enquiries received relating to existing outbreaks.

It’s also important to note that single site products in the following list should not be used curatively against existing infections.

Active constituents Notes Restriction on use
Powdery mildew Potassium bicarbonate (Ecocarb) Eradicant properties, no protective activity Use no later than 7 days before harvest
Hydrogen Peroxide+peroxy acetic acid Suppression only Use no later than 7 days before harvest
Sulfur Protectant Use no later than 30 days before harvest
Botrytis Potassium salts of fatty acids(Ecoprotector) Protectant with eradicant properties Use no later than 14 days before harvest
Hydrogen Peroxide+peroxy acetic acid Suppression only Use no later than 7 days before harvest
Iprodione Protectant Use no later than 7 days before harvest. Consult your purchaser before spraying within 30 days of harvest

For more details please consult the 13/14 Dog Book and your winery.

The Dog book is also available as an app that can be downloaded for free from iTunes or Google Play.

Further assistance: The AWRI offers a free and confidential help desk service on technical issues, to all Australian grapegrowers and wine producers. Should you require further assistance, please call the AWRI’s help desk on 08 8313 6600 or email: viticulture@awri.com.au.

Technical Review February 2014 issue now available online

6 February 2014 >

The February 2014 issue of Technical Review is now available for viewing online and for downloading. Articles and abstracts can be viewed individually, or the full issue can be downloaded. 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.

Below is a snapshot of what’s in this issue:

AWRI Technical Notes
  • Measuring oxidative aroma compounds in wines
  • Napping – a rapid method for sensory analysis of wines
AWRI publications
  • Optimising fermentation through simulation
  • Effect of wine pH and bottle closure on tannin
  • Ask the AWRI: Understanding the ABCs of CMCs in solution
Current literature – oenology
  • White wine aroma optimisation
  • Co-fermentation of Syrah with various additions of Viognier: effect on colour and phenolics during winemaking and bottle ageing
  • Potato, a new source of vegetal protein for allergen-free fining of juice and wine
  • Impact of dissolved oxygen at bottling on sulfur dioxide and sensory properties of a Riesling wine
Current literature – marketing and packaging
  • Why do people avoid consuming wine?
  • The wine headache: consumer perceptions of sulfites and willingness to pay for non-sulfited wines
Current literature – viticulture
  • Wine aroma and grapevine berry ripening: how to capture the complexity
  • Wine sector attitudes to the adoption of Precision Viticulture
  • Organic inputs for disease management in organic blocks
  • Understanding fungicide resistance in Australian vineyards

Please click here to access the February 2014 issue of Technical Review.

eNews – January 2014

10 January 2014 >

Pre-vintage reminder on Brett avoidance and control
Making the most of your smart phone or tablet in the vineyard
Refrigeration and wastewater workshops
Encouraging Chinese consumers to choose Australian wines
Nobel Prize winner to join the AWRI Board
Partnerships bring new opportunities
Well-deserved recognition for Mardi Longbottom
AWRI Annual Report available online
Recent literature

Pre-vintage reminder on Brett avoidance and control

With another vintage just around the corner (or already commenced in some of the warmer regions) it is a good time to brush up on the winemaking practices that can help to avoid Brettanomyces spoilage. As harvest is such a busy time of year and often involves new staff members, simple procedures can be overlooked in the rush. The AWRI has put together a list of tips that will help you stay on top of Brett prevention.

  1. Sulfur dioxide is Brett’s worst enemy and the sooner you can make additions to harvested fruit, the better. Machine harvested fruit is particularly in need of protection, so consider a 100 g/tonne addition of potassium metabisulfite (PMS) to bins.
  2. High pH favours Brett growth so if you know that your must is likely to have high pH, make an acid addition at the crusher. As soon as you know the pH of the homogenised must (make sure the sample is representative) adjust the pH if necessary. Red musts should be adjusted to below pH 3.4 whilst aiming for a titratable acidity (TA) of about 7.5 – 8.0 g/L. However, if the desirable TA cannot be achieved, then the must should be adjusted to pH 3.4 or below regardless of the amount of tartaric acid required to do so. Note that a large amount of the acid added will drop out later as potassium bitartrate (KHT), resulting in a decrease in the TA in the finished wine.
  3. During fermentation, potassium ions are leached from grape skins, resulting in a pH rise. It is recommended, therefore, that pH be measured during fermentation on skins and additions should be made to maintain the pH in the range 3.4 – 3.5. If the pH of the resulting wine is greater than 3.6, then precipitation of KHT will result in an increase in pH, which is undesirable because high pH favours Brett growth. If the wine pH is less than 3.6, then precipitation of KHT results in a decrease in pH, which is more desirable.
  4. Ensure that all winery and vineyard equipment such as grape bins are sanitised regularly and that wine hoses are drained of cleaning water. Water combined with sugar is an ideal breeding ground for a host of spoilage microorganisms.
  5. Ensure red ferments are healthy with a sufficient yeast cell population to complete ferment; Brett growth is highly favoured in the presence of residual sugar. Keep ferments warm towards the end, particularly once off skins, and check residual sugar levels, especially if going straight to barrel.
  6. Barrels can be a major source of contamination; if you have any suspect barrels you can get them tested through the AWRI’s Commercial Services https://www.awri.com.au/commercial_services/analytical_services/analyses/4ep-4eg/.
  7. Whilst various forms of barrel cleaning are available, if you have a history of Brettanomyces contamination the recommended treatment is to fill barrels with hot water at 85°C for fifteen minutes or until the exterior of the barrel is hot to touch. Take the time to check that your hot water thermostat is accurate pre-vintage and make sure staff are aware of the OH&S issues associated with working with hot water.
  8. Malolactic fermentation (MLF) is a critical period for avoiding Brett contamination and growth. Ensure that pH levels never get higher than 3.6 by adjusting early (see points 2 and 3), keep barrels topped and ensure that barrels are sulfured as soon as you know MLF is complete. A large SO2 addition is better than multiple small ones, so consider an 80 mg/L addition post MLF.
  9. If you take one action this vintage to control Brett, do this: add a column for molecular SO2 (MSO2) to your lab analysis sheet. Molecular sulfur dioxide is determined by the relationship between pH and free SO2, and it is recommended to maintain levels above 0.6 mg/L. To calculate MSO2, you can use the AWRI’s online calculator https://www.awri.com.au/industry_support/winemaking_resources/calculators/molecular-sulfur-dioxide/ or the AWRI winemaking calculators app https://www.awri.com.au/industry_support/winemaking_resources/winemaking-calculators-app/.

Making the most of your smart phone or tablet in the vineyard

Smart phones and tablets have rapidly transformed the way in which data and information can be obtained, collected and stored. With the increasing access that grapegrowers and viticulturists have to these tools, there are substantial resources and digital technologies available to increase productivity and efficiency and improve vineyard management.

The AWRI has developed a practical, hands-on workshop to be delivered during 2014 to assist grapegrowers in integrating smart phones and tablets into the management of their businesses. The workshop will be launched in the Barossa Valley and McLaren Vale next week.

Topics covered will include internet access, different technology platforms, data plans and coverage, tools to assist in working remotely, accessories, mobile security, apps relevant to vineyard management and viticultural businesses, and social media.

Dates and venues for the two launch workshops are :
15 January 2014, 9am-1pm – Barossa Weintal Resort, Tanunda SA
16 January 2014, 9am-1pm – McLaren Vale Visitor Centre, McLaren Vale SA

To book a place, please contact Paula Edwards on 08 8323 0056 or paula.edwards@winegrapes.com.au.

For more information, or if you think the growers in your region could benefit from attending this workshop, please contact Peter Godden on peter.godden@awri.com.au or 08 8313 6600.

Refrigeration and wastewater workshops

AWRI Commercial Services engineers are running two winery operations workshops in WA next week. The one-day workshops will focus on winery refrigeration and wastewater – key areas for reducing costs and improving environmental impact. The workshops will take place at the following dates and locations:

14 January, 9am-4.30pm – Faber Vineyard, Baskerville WA
16 January, 9am – 4.30pm – Cape Mentelle, Margaret River WA

To register, contact Jodie Panel at Wines of Western Australia by fax: 08 9284 4211, phone: 08 9284 3355 or email: reception@winewa.asn.au

If you are interested in bringing a similar workshop to your region, please contact Eric Wilkes, Group Manager – Commercial Services on eric.wilkes@awri.com.au or 08 8313 6600.

Encouraging Chinese consumers to choose Australian wines

Messages about the good quality and taste of Australian wines are most effective in encouraging Chinese consumers to choose Australian wine, compared to other communications about Australia. When consumers in China were told in a magazine article that Chinese people in general prefer the taste of Australian wines, their choice of Australian wine increased significantly over French, Italian and Chinese wines. This key result comes from a collaborative project investigating the impact of different messages about Australia on the wine purchasing behaviour of consumers in China

Apart from the taste message, the next most influential message in encouraging choice of Australian wines was one highlighting Australia’s clean unpolluted environment. An article about Australia’s great beaches and tourist attractions was the least effective, although there was still a positive response compared to a control group. Wine ratings and shelf communication were also shown to be very important for Chinese consumers when choosing a wine to buy.

The project was completed in August with over 1600 Chinese consumers of imported red wine exposed to five different messages about Australia in the form of advertorial-type articles, after which they made purchase selections in a simulated retail situation. The project was conducted by the AWRI sensory team, working with a group of wine industry advisors, as well as Larry Lockshin at UniSA and Simone Mueller-Loose at the University of Aarhus.

The second phase of this project is currently underway and involves consumers tasting Australian, Chinese and French wines under both blind and informed conditions. The results will be presented in another webinar by Patricia in February – watch this space!

Nobel Prize winner to join the AWRI Board

Winemaker and Nobel Prize-winning astronomer, Prof. Brian P. Schmidt, AC, FAA, FRS will join the AWRI Board as a special qualifications director in February 2014.

Brian is a Distinguished Professor at the Australian National University Research School of Astronomy and Astrophysics. He shared the 2011 Nobel Prize for Physics with Saul Perlmutter and Adam G. Riess for the discovery of the accelerating expansion of the Universe. He was elected Fellow of the Royal Society in 2012 and appointed a Companion (AC) in the General Division of the Order of Australia in 2013. He is a non-executive Director of Astronomy Australia, a member of the Council of the Australian Academy of Science and serves on three Government advisory boards.

Brian is also the owner operator of Maipenrai Vineyard and Winery in the Canberra District – a small producer of high quality Pinot Noir wines.

Brian gave the opening address at the 15th AWITC where he spoke about the importance of creativity and risk-taking in science.

Partnerships bring new opportunities

The AWRI has recently confirmed its involvement in three partnerships, one Australian and two international, that will bring benefits to the Australian wine industry.

The first is a partnership with the Ramaciotti Centre for Genomics at the University of New South Wales which will apply metagenomics techniques to map the composition of wild ferments. This work aims to shed light on the contribution of microbes to wine regional character. Knowledge gained will allow winemakers to take full advantage of local wild yeast and bacteria. It will also enable new yeast and bacteria strains to be developed, drawing on existing regional diversity and the AWRI microbial germplasm collection assembled over the past 50 years.

The second is an international alliance (known informally as the ‘BAG’ alliance) with the Institute of Vine and Wine Sciences (ISVV) (Bordeaux, France) and the Hochschule Geisenheim University (HGU) (Geisenheim, Germany). This partnership will involve cooperation on research areas of mutual interest, exchange of people, projects and information as well as the sharing of infrastructure and expertise across the grape and wine value chain. The Government of South Australia is supporting the new alliance through the Premier’s Research and Industry Fund.

Four areas of priority for collaboration have recently been identified for the BAG alliance:

  • Adaptation to climate change
  • Management of the spoilage yeast Brettanomyces
  • Grapevine trunk diseases
  • Consumer behaviour in China

Projects in these four areas will launch early in 2014.

The third partnership is a continuation of the AWRI’s successful collaboration with the Institute of Masters of Wine (IMW), under which the two organisations provide support to each other’s extension and education programs.

The AWRI hosted the IMW’s Australasian seminar in November, and gave a presentation on wine faults and taints to the MW students. Members of the IMW are likely to contribute to AWRI extension events over the next two years. The collaboration also allows the AWRI to access wines that are not available in Australia and import them for use in tasting programs, most recently the successful World Chardonnay and Pinot Noir tasting. In May 2014, Peter Godden will be presenting at the IMW’s 8th Symposium, in a session on the frontiers of wine research.

Well-deserved recognition for Mardi Longbottom

AWRI Viticulturist Mardi Longbottom has received recognition of a very successful 2013 with two awards. She has won a place in the Governor’s Leadership Foundation program for 2014, with a full scholarship provided by Primary Industries and Regions SA (PIRSA). Mardi was also the recipient of the 2013 AWRI Innovation award.

The Governor’s Leadership Foundation (GLF) program contributes to the prosperity of South Australia by inspiring South Australians with leadership potential through enhancing their self-awareness, emotional intelligence, problem solving analysis and strategic foresight ability. The 10-month program is delivered through a mix of:

  • seminars;
  • forums;
  • field trips;
  • individual coaching sessions; and
  • group work.

The AWRI Innovation award is awarded annually, with a shortlist drawn up based on nominations and voting by AWRI staff, and the final winner chosen by a Board sub-committee. Mardi was recognised for her success in initiating and financing several extension activities of relevance to grapegrowers, adding to the AWRI’s existing service offering to winemakers.

AWRI Annual Report available online

The AWRI’s 2013 Annual Report is now available from the AWRI website. You can download a copy in pdf format or browse through an eBook version.

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

1569 Mangoni, A.A., Stockley, C.S., Woodman, R.J. Effects of red wine on established markers of arterial structure and function in human studies: current knowledge and future research directions. Expert Rev. Clin. Pharmacol. 6 (6): 613-625; 2013.

1570 Coulter, A. Ask the AWRI: Understanding the ABCs of CMCs in stabilisation. Aust. N.Z. Grapegrower Winemaker (598): p. 72; 2013.

1571 McRae, J.M., Kassara, S., Kennedy, J.A., Water, E.J., Smith, P.A. Effect of wine pH and bottle closure on tannins. J. Agric. Food Chem. 61 (47); 2013.

1572 Kidman, C.M., Mantilla, S.O., Dry, P.R., McCarthy, M.G., Collins, C. The effect of water stress on reproductive performance of Shiraz (Vitis Vinifera L.) grafted to rootstocks. Am. J. Enol. Vitic. doi: 10.5344/ajev.2013.13069; 2013.

1573 Jolly, N. P., Varela, C., Pretorius, I. S. Not your ordinary yeast: non- Saccharomyces yeasts in wine production uncovered. FEMS Yeast Res. doi:10.1111/1567-1364.12111; 2013.

1574 Longbottom, M. Greenhouse gas abatement in viticulture. Aust. N.Z. Grapegrower Winemaker (598): 35-38; 2013.

1575 Muhlack, R., Scrimgeour, N., Wilkes, E., Godden, P., Johnson, D. Optimising fermentation through simulation. Wine Viti. J. 28 (6): 38, 40-43; 2013.

1576 Dry, P. Schönburger. Wine Viti. J. 28 (6): p. 58; 2013.

1577 Viviers, M.Z., Smith, M.E., Wilkes, E., Smith, P. Effects of five metals on the evolution of Hydrogen sulphide, Methanethiol, and Dimethyl sulphide during anaerobic storage of Chardonnay and Shiraz wines. J. Agric. Food Chem. doi.org/10.1021/jf403422x: 12 p.; 2013.

1578 Johnson, D. Fascinating story to tell. Aust. N.Z. Grapegrower Winemaker (599): p. 30; 2013.

1579 Dry, P. If the grape fits then you can grow it. Aust. N.Z. Grapegrower Winemaker (599): p. 57; 2013.

1580 Muhlack, R., Forsyth, K., Scrimgeour, N., Godden, P. There’s gotta be a buck in those organic by-products. Aust. N.Z. Grapegrower Winemaker (599): 80-82; 2013.

1581 Johnson, D. 2013 Report: Planning for the future. Aust. N.Z. Grapegrower Winemaker (598): 81-84; 2013.

1582 Tran, T., Wilkes, E. How does CMC behave in NZ wines? NZ Winegrower (83): 67-69; 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.

Two current issues: heatwave warning and impact of elemental sulfur residues

9 January 2014 >

Preparing for the impending heatwave across Southern Australia

Central parts of Western Australia are currently experiencing the start of heatwave conditions. These extreme temperatures will extend over southern Western Australia through Friday 10 January and extend across South Australia through Saturday and Sunday. From Sunday 12 January a period of heatwave conditions will be in place across much of southern Australia, with temperatures increasing for most areas through the following week, and peaking on Friday 17 January. There is a possibility that extreme temperatures could remain in place for many areas past that date. Growers should be aware of the tools available to predict heatwaves and the steps that can be taken to minimise vine damage.

Extreme heat after veraison (as grapes soften) may cause berry shrivel or sunburn and grapevine function can be severely impaired. Irrigation management is critical before, during and after a heat event:

  • Before the heat arrives, apply irrigation to enable leaf cooling that occurs when leaves transpire. Postpone any canopy manipulation (leaf removal or canopy lifting) 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 can cause the canopy to roll over and expose the fruit. Look to implement management strategies which can reduce the likelihood of this occurring.
  • After the heatwave, irrigate to replace lost soil moisture and decrease soil temperature. Monitor for pests and disease that may exploit damaged berries.

To monitor expected conditions through the event, Bureau of Meteorology (BOM) 7 day forecasts of temperatures can be seen via the Met Eye tool http://www.bom.gov.au/australia/meteye/

A pilot project heatwave warning service was released by the BOM on 8 January http://www.bom.gov.au/australia/heatwave/. This indicates areas likely to experience prolonged high maximum and minimum temperatures over the following three-day period from each start date, covering up to a week ahead. Feedback from this pilot service will be valuable in establishing the usefulness of this product for the grape and wine industry and can be submitted via this link http://www.bom.gov.au/other/feedback/

More detailed information on managing grapevines during heatwaves can be found in the GWRDC Innovators Network factsheet.

Elemental sulfur residues – potential impact on fermentation and management strategies

Due to recent outbreaks of powdery mildew across warmer areas of SA, NSW and Victoria, the AWRI help-desk team has received several queries regarding the effectiveness of elemental or crystalline sulfur on Powdery Mildew infections, and the possible impact residues might have on fermentation.

Background

Elemental sulfur is classed as a non-systemic protectant fungicide that is best used prior to powdery mildew infection. It will not eradicate an existing powdery mildew infection but it can inhibit mycelia growth and spore germination. This reduces disease development and infection; however good coverage is critical.

For the control of Powdery Mildew, the AWRI recommends a thirty day withholding period (WHP) for elemental sulfur. Applications within the WHP increase the risk of residues entering the must. This may lead to fermentation issues as detailed below. The WHP is set to allow enough time for elemental sulfur to oxidise to sulfur dioxide (SO2) and degrade to levels that reduce the potential for fermentation problems. Research indicates that as the length of time between the application of sulfur in the vineyard and harvest increases, the impact on fermentation declines.

Contact your winery or grape purchaser before using sulfur within 30 days of harvest.

Implications

Elemental sulfur residues in must can be converted under the reducing conditions of fermentation to hydrogen sulfide (H2S), which imparts the objectionable odour of rotten-eggs. Hydrogen sulfide may then undergo reactions with other wine components to form mercaptans, which can have detrimental effects on wine quality and which may be difficult to remove.

The main factors that control H2S production from elemental sulfur are:

  • pH and temperature (more H2S is produced at lower pH and higher temperature);
  • reduction potential (more H2S is produced at higher reduction potential – i.e. more H2S is formed when there is very little, or no oxygen, available); and
  • ethanol concentration (less H2S is produced at lower ethanol concentrations).

Given higher H2S production is associated with residual sulfur, it is best to use a yeast which is classified as a low H2S producer.

In white wine production, the problems resulting from the presence of dusting sulfur in the juice can be reduced by careful settling and racking of the juice before fermentation, as the sulfur should settle out with the lees.

It is advisable to ensure adequate YAN (yeast assimilable nitrogen) levels in juice to facilitate good yeast performance and manufacturer recommendations should be carefully followed when rehydrating active dried wine yeast. In addition, the yeast may benefit from rehydration with inactivated yeast preparations, which contain a range of micronutrients including amino acids, lipids and minerals. Higher than usual yeast inoculum rates could also be beneficial, in order to compensate for the possible negative effects residual elemental sulfur might have upon the yeast.

Once the ferment is actively fermenting, aeration in combination with a DAP addition will not only decrease the reduction potential (decreasing the amount of H2S produced), but will boost yeast performance. Aeration should be performed between one third and half-way through fermentation (i.e. when one-third to one-half of the sugar has been consumed). A steady fermentation rate should be maintained by minimising temperature fluctuations, and high fermentation temperatures should be avoided.

It is best to treat wines exhibiting H2S aromas due to residual sulfur with copper just prior to the completion of fermentation (approximately 1 Baumé) in order to avoid stressing the yeast, as it is likely a larger than usual amount of copper will be required. The likelihood of residual copper problems is also reduced if the copper is added at this time, as the yeast will bind up any excess copper that might be present. For more information, see FAQ.

Further assistance

Should you require further assistance regarding heatwaves or elemental sulfur use, please contact the AWRI help-desk on 08 8313 6600 or by email.

Timely reminder about disease risk

13 December 2013 >

The overcast and cool conditions experienced across much of south-eastern Australia this season have elevated the disease risk from powdery mildew. This is a timely reminder to ensure you are following regional crop watch reports and taking note of any warning systems that service your region. Regular monitoring is the only way to know how well your spray program and cultural practices are working at suppressing disease.

Note that wet conditions will also favour the development of weather-driven pathogens such as downy mildew and botrytis.

Recommended actions:

  • Monitor your vines and the weather and act early if conditions favour disease.
  • Unfavourable conditions (wet or windy) can make vineyard access problematic. Schedule shorter spray intervals where possible.
  • Make sure you’re hitting the target with the right chemical dose applied before infection takes hold. Low water rates might be ok when disease pressure is low but in unfavourable conditions, good coverage is essential.
  • In wet seasons, grapevine canopies can be vigorous. Extra effort is needed to open canopies for improved spray penetration and increased airflow.

Monitoring for powdery mildew should be focused on previously infected areas, shaded or dense parts of vine canopies, and sheltered vineyard sites, particularly in humid and overcast weather. Conditions that are mild (20-30°C) and cloudy, coupled with low to moderate light, favour disease spread.

powdery-mildrew
Grapevine showing typical powdery mildew symptoms,- powdery ash-grey spores on leaves, berries and bunch stalks.

In the right conditions, powdery mildew can produce a new generation in 5-12 days. The infection cycle should be controlled as quickly as possible. This requires good spray penetration into the canopy and rotation of chemical groups to reduce the risk of resistance.

Follow this link to Q&A on powdery mildew.

This season, evidence of downy mildew has been found in South Australia and Victoria. Weather driven, this disease needs moisture and warm conditions. Temperature, rainfall, relative humidity and leaf wetness are all indicators of risk for this disease.

downey-mildrew
Downy mildew oil spot and down like symptoms on grapevine shoots.

Cultural practices that open the canopy and promote leaf drying reduce disease risk. Spray programs that prevent infection of leaves and bunches need to be applied with good coverage and before the infection event. Post infection fungicides are best applied soon after an infection and before oil spots appear.

Follow this link to Q&A on downy mildew.
Vineyards affected by hail or frost will be at increased risk of botrytis infection to damaged tissue. Botrytis can also be a problem when wet weather occurs late in the season. Canopies should be managed to promote airflow and thus reduce the chance of spore germination. Flowering and pre-bunch closure sprays are recommended in susceptible vineyards. Minimising damage to bunches caused by insect pests, careful wire lifting and a well-spread bunch zone can also reduce botrytis levels at harvest.

Follow this link to Q&A on botrytis.

Further assistanceThe AWRI offers a free and confidential help desk service on technical issues, to all Australian grapegrowers and wine producers. Should you require further assistance, please call the AWRI’s help desk on 08 8313 6600 or email: viticulture@awri.com.au.