The Australian Wine Research Institute

Didn’t see that coming – how did that get there?
Power generation from grape marc – soon to be a reality
Are consumer preferences constant?
Good things come in small packages: micro-scale fermentations at WIC Winemaking Services
Experienced chemist and well respected industry technician joins the AWRI
Read up on alternative grape and vine varieties

Didn’t see that coming – how did that get there?

Calcium levels in wine are traditionally not something that you would be checking in juice or wine, but a number of wines investigated by the AWRI’s Winemaking and Extension Services (WES) team recently, containing crystals, in particular calcium tartrate crystals, would suggest otherwise.

Calcium levels in wine are typically low, or have they been creeping up in recent times? While calcium occurs naturally in grapes and wines, levels can be elevated by the use of calcium salts as additives or fining agents, such as deacidification with calcium carbonate, skim milk and calcium based bentonites. It has been suggested that there is a real risk of calcium tartrate precipitation when the level of calcium is over 60 mg/L in red wines and 80 mg/L or more in white wines (Ribereua et al. 1977). Further reading on calcium and CaT deposits can be found here. If you are not aware of the calcium levels in your wines, then you might not see this potential problem coming.

Power generation from grape marc – soon to be a reality

Wine producers in the Riverland could soon be using power generated from grape marc. The AWRI has been working on the feasibility of extracting bioenergy from grape marc for a number of years and, in 2009, the AWRI’s Dr Richard Muhlack won an Australian Government prize awarded by the Department of Agriculture, Fisheries and Forestry (DAFF) for his work in this area. Now, a grape marc bioenergy facility will be built.

Our aim has been to examine marc and grape stalks for their calorific value and combustibility under various conditions, in order to produce reliable data on which business cases for the implementation of this technology might be based. Recently, Tarac Technologies (a partner in our 2009 DAFF bio-energy project) together with Murrumbidgee Irrigation (MI), issued an invitation to tender for design and construction of a 10MWth grape marc bioenergy facility (estimated project cost > $10m) to be located in Griffith NSW. Coincidentally, Richard Muhlack re-located from Adelaide to Griffith in November 2010, in order to manage our newly-established AWRI Riverina Node. According to the tender invitation document, Tarac and MI intend to sell surplus (renewable) electricity to other local large energy users, which would inevitably include wine Riverina wine producers. This demonstrates great confidence in grape marc bioenergy technology, and we consider this is a big win; it de-risks the technology, and hopefully will provide necessary momentum for similar developments in other wine regions. For further information contact Richard Muhlack.

Are consumer preferences constant?

Can a person’s taste preferences be altered? Are likes and dislikes static, due to genetics or early upbringing and only changing over the long-term, or can they be influenced by recent wine experiences? We’ve shown that there can be a marked change in preference after different wine encounters, especially for newer wine consumers, and confirmed that opportunities to expose consumers to wines will affect their responses.

In two linked studies we have assessed short-term changes, either due to repeated experience with different wine types or due to a wine education course. While consumers can’t be persuaded to appreciate wines they previously disliked, many can have greater enjoyment of wines with higher fruit and oak flavour than they previously demonstrated.

After two weeks of exposure to different wines, consumers had increased liking scores of wines with similar characteristics to the wine they were exposed to, whether a more complex, higher flavoured style or a lighter and sweeter type.

In the second study, many consumers changed preferences after a tasting course towards wines with greater fruit intensity and away from wines with a degree of bitterness or stronger acidity.

For more information please contact Patricia Osidacz.

Good things come in small packages: micro-scale fermentations at WIC Winemaking Services

Need to run a micro-scale fermentation to test for agrochemical residue, or perhaps you want to check out how that single vine new variety might perform? Replicated trials can now be performed at WIC Winemaking Services, under the care of Gemma West, an experienced and qualified winemaker.

The WIC Winemaking Service can run a series of 5 kg-scale (for red and white fruit) replicated trials, using a variety of temperature controlled rooms which enable good results even with more hostile treatments such as those in agrochemical residue trials.

Trials can be designed to include high-end chemical or sensory analysis. The new micro-fermentation capability complements WIC Winemaking Services’ current offering of replicated small- and pilot-scale winemaking.

For further information, please contact Gemma West or on telephone (08) 8313 6600.

Experienced chemist and well respected industry technician joins the AWRI

With his appointment to the AWRI as Research Manager – Industry Applications, Eric Wilkes is looking forward to working with wine producers around Australia to assist them to adopt beneficial technologies and practices.

Eric has worked in the beverage industry since completing his PhD in chemistry at the University of Newcastle in 1997, where he held both teaching and technical positions. Initially spending four years based in the Hunter Valley with the then independent Rosemount Estates he moved to SA in 2001 to take up the role of Group Chemist with the Foster’s Wine Group based at the Wolf Blass Winery. In 2007 he accepted the role of Global Manager Analytical Services with the Foster’s Group overseeing the integration and alignment of testing and technical services across their whole beverage portfolio on three continents; and in 2010 he joined P&N Beverages in Sydney as National Technical Manager with responsibility for new product development, product QA, customer feedback and product compliance. Specialising in technical management he has extensive experience in successfully integrating new technologies and systems into wine production and improving those already in place. He is also a past committee member of the Interwinery Analysis Group and the co-author of a book on wine laboratory analysis. Eric was already well known to many AWRI staff members who have worked with him on many collaborative projects over the years, and we have always been impressed by his wealth of knowledge and experience across many areas of expertise, not to mention his affable nature; which is why we recruited him! Eric has hit the ground running in his new role, and we are sure he will turbo-charge many of our Development projects.

Read up on alternative grape and vine varieties

A recent addition to the AWRI’s Research to Practice series is ‘Alternative varieties: emerging options for a changing environment’. The AWRI’s John Fornachon Memorial Library supports staff by sourcing references to aid their research. Some of the books on alternative grape and vine varieties, added to our book collection during the course of producing the Research to Practice handbook, are listed.

Library books are available for loan and can be searched and requested via the Library catalogue – or you can email us with your request.

• Bettiga, L.J., Christensen, L.P., Dokoozlian, N.K., Golino, D.A., McGourty, G., Smith, R.J., Verdegaal, P.S., Walker, M.A., Wolpert, J.A., Weber, E. Wine grape varieties in California. iv, 188 p., 2003.
• Bohm, J., Gato, O., Laureano, P. The grapevine varieties from Alentejo. 17 p., 1999.
• Higgs, D. Emerging varietal wines of Australia : a guide for the adventurous winelover. ix, 209 p., 2005.
• Ministère de l’agriculture et de la pêche – CTPS. Catalogue des varietes et clones de vigne cultives en France [Catalogue of selected wine grape varieties and certified clones cultivated in France]. 455 p., 2007.
• Tassie, L. Dry, P. Essling, M. Alternative varieties: emerging options for a changing environment. xiv, 142 p., 2010.

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.

Ensure your export wine specifications receive a tick of approval
Did you have a difficult or slow malo this vintage? Have you considered co-inoculation?
If you are only measuring DO, you need your head read
Getting a grip on tannin composition and wine astringency
Yeast strain flavour differences keep on keeping on
Join the rush for cheap, fast analysis results
Another 30 graduate from our 30th AWAC tasting boot camp
What is that smell? Call us to find out
Recent publications from AWRI staff members

Ensure your export wine specifications receive a tick of approval

How do you know that the wine you export meets the destination country’s regulations? How confident are you that the processing aids you used are permitted in that country? The AWRI’s website can provide this information.

The AWRI website provides specific information as to what additives and processing aids are permitted in different countries. Plug in one of the 244 additives or processing aids you wish to use, and the database will tell you which countries permit its use. Alternatively, plug in the country you wish to export to (there are 15 countries/markets listed) and the database will tell you which additives or processing aids are permitted. The two databases are called Permitted additives and processing aids for winemaking and wine importing countries and Analytical specifications for the export of Australian wine. Both of these databases were updated this month. The latter contains specifications for 38 countries/markets. While the databases don’t provide a complete list of all the countries to which Australia exports wine, it includes those which have made available their winemaking regulations. Please contact the Health and Regulatory Information Manager for further information.

Did you have a difficult or slow malo this vintage? Have you considered co-inoculation?

Want to put your wine through malo (malolactic fermentation/MLF) but are worried about the risks of spoilage through a prolonged or delayed MLF? There is a solution.

Malolactic fermentation typically occurs after alcoholic fermentation (AF) and can occur spontaneously by the action of indigenous bacteria populations, or can be induced by the winemaker via inoculation with a starter culture. A prolonged or delayed MLF increases the risk of spoilage by other microorganisms, such as Lactobacillus, Pediococcus and Brettanomyces.

A recent trial on the timing of MLF inoculation in Shiraz grape must and wine has shown that a co-inoculation (yeast and bacteria together from the beginning) can reduce the time for MLF by up to 6 weeks. Four different inoculation points were compared (co-inoculation, mid-alcoholic fermentation [AF], at pressing and post-AF). Not only can co-inoculation reduce the overall total time for fermentation (AF + MLF) thus allowing wine to be stabilised earlier, but the wine volatiles profile was distinct from wines produced when bacteria were inoculated late or post-AF.

You can access the paper describing the work via the AWRI library:

Abrahamse, C.E., Bartowsky, E.J. Timing of malolactic fermentation inoculation in Shiraz grape must and wine: influence on chemical composition. World Journal of Microbiology and Biotechnology DOI 10.1007/s11274-011-0814-3; 2011.

If you are only measuring DO, you need your head read

We constantly see wines compromised by poor bottling practices. These wines show evidence of loss of fruit character, or have reached their shelf life within six months of bottling due to high oxygen exposure. We can help your bottling operations protect the quality of your vintage ’11 wines.

To ensure your wines are being bottled with the diligence they deserve, the total package oxygen (TPO) levels must be measured. TPO is the combination of both the dissolved oxygen in the wine, plus the oxygen in the headspace. Best practice management of TPO is achieving levels of less than 1.0 mg/L; and less than 2.5 mg/L is regarded as acceptable. In one particular audit we measured TPO at levels approaching 10 mg/L! If you thought sparkling wines aren’t affected, think again!

The AWRI’s Commercial Services has benchmarked over 20 bottling lines across Australia and New Zealand. Whilst oxygen management performance varies greatly, typically 70% of total oxygen is in the headspace. Therefore, just measuring dissolved oxygen has limited value, as it cannot quantify how well the wine was bottled. To have confidence in the quality of your bottling operations, you must measure and manage the TPO.

The AWRI’s Commercial Services is in the process of introducing a TPO accreditation to provide wineries with the confidence that their selected bottling facility has the capability to comply with best practice bottling guidelines. This accreditation will be available to bottlers who can demonstrate acceptable TPO performance and a robust QC regime.

If you require assistance to benchmark the TPO proficiency of your bottling line, or access to our online TPO calculator, please visit our website, or contact the team at AWRI Commercial Services.

Getting a grip on tannin composition and wine astringency

Ever had to peel the inside of your cheeks from your teeth, after a sip of a particularly astringent red wine? Do you know how those puckery tannins will contribute to the mouth-feel of your wine in two, five or ten years? This is something we’re helping winemakers to get a grip on. Tannin concentrations have shown to impact greatly upon red wine astringency, but this doesn’t tell the whole story of why astringency softens as wine ages. Current investigations are delving deeper into the role of tannins in wine, in particular how their composition affects the astringency quality.

Astringency is a complex sensation that involves the binding of tannins to salivary proteins and other surfaces in the mouth. Greater concentrations of tannins have been shown to bind to more proteins and therefore the sensation of astringency is increased. Recent analysis using isothermal titration calorimetry (ITC) has shown that the composition of tannins impacts upon the strength of the protein interaction. This is particularly pronounced when comparing the binding strength of tannins from two year old wines with those from ten year old wines, with older wine tannins interacting comparatively weakly with proteins. These results may also provide some explanation as to why some wines have a harsh and puckering astringency when the tannin concentration is the same as other wines that have a smoother, more velvety astringency.

You can access the paper describing the work via the AWRI library:

McRae, J.M. Falconer, R.J. Kennedy, J.A. Thermodynamics of grape and wine tannin interaction with polyproline: implications for red wine astringency. Journal of Agricultural and Food Chemistry 58 (23) : 12510–12518; 2010.

Yeast strain flavour differences keep on keeping on

You might have read about some of our work on yeasts that bring out different flavour compounds from the grape, over traditional wine yeast, through the fermentation process. But does the effect last? Many winemakers believe that while yeast strains might have a flavour effect in a young wine, any differences disappear after a short time in bottle. This has been disproved.

We conducted a study over two vintages, on Sauvignon Blanc fermented using a number of yeast strains, and cellared for three years. Sensory differences among the wines assessed soon after bottling were still clearly evident after this extended cellar storage. Aroma volatile compositional differences in the young wines, in particular those of the potent ‘tropical’ thiols, were also found to be retained.

You can access the paper describing the work via the AWRI library:

King, E.S., Francis, I.L., Swiegers, J.H., Curtin, C. Yeast Strain-Derived Sensory Differences Are Retained in Sauvignon blanc Wines after Extended Bottle Storage. American Journal of Enology and Viticulture DOI 10.5344/ajev.2011.10079; 2011.

Join the rush for cheap, fast analysis results

Our prices have dropped – see how we do it on our CSI speedy-lab video. Also, watch out for ‘Brett’. Put your mind at ease that no unwanted flavours sneak into your wine and have our experts check it out for you.

• Reduce the costs of export approval
  • We are now offering substantially cheaper analysis for export certification testing (less than half price for some tests). The service includes testing within 24 hours of sample receipt and free delivery of samples to Wine Australia for product approval inspections. See the AWRI website for further information.
• Are you exporting your wine to a market sensitive to Vegans such as India?
  • If so, screening your wine for the presence of dairy products such as the milk protein casein, and egg residue is critical. Cost per sample is $90 (excl. GST) or $160 (excl. GST) for the two analyses combined.
• Watch out – you are now in the Brett Zone!
  • It’s that time of year… primary fermentation is complete but cooler temperatures may mean struggling malo ferments; wines have low SO₂ and are ripe for Brett attack. Wines with low SO₂, high pH and residual sugar can also be at risk. Call us for a bandaid solution.

Another 30 graduate from our 30th AWAC tasting boot camp

Congratulations to another 30 boot camp recruits, who successfully completed our 30th AWAC held at Penfold’s Magill Estate in the last week of June. There were lots of great discussions of wines… what makes a good Shiraz? What’s the future of Chardonnay? What are the best performing alternative varietals? Check out some of the comments @The_AWRI #AWAC twitter account, now up to 600 followers.

As with previous courses, there were a few disappointing international benchmarks. Got any recommendations for us? Con wants to know, email Con at con.simos@awri.com.au. Congratulations to Peter Lehmann Wines… wine of AWAC again was the 2002 Peter Lehmann Reserve Riesling. Thanks also to our passionate guest judges who continue to drive and inspire our future wine judges and industry members who want to improve their palates. Stay tuned to find out who will be this year’s AWAC Dux. The winner will be offered a place as an associate judge at the 2012 Royal Adelaide Wine Show. Interested in attending AWAC 31? Register here.

What is that smell? Call us to find out

Got a smelly wine but you don’t know what it is? Don’t know how to restart that stuck ferment? Received some laccase results, but not sure how to interpret them? Not sure whether there is a higher incidence of cork taint in your wine? Call our winemaking help desk!

Our winemakers Con, Adrian, Geoff and Matt are at the ready to help you find out what is happening with your wine. If we can’t help you out over the phone, you can send samples to us for tasting, analysis and anything else to get to the bottom of the problem for you. We will even write up legal reports if needed for insurance claims or disputes. All this is free for winemakers who pay the Winegrapes and/or Grape Research levies. Find out more about what we offer here, or see our recent eBulletin. Call us on 08 8313 6600 or email winemakingservices@awri.com.au.

Recent publications from AWRI staff members

Research articles and books can be requested from the John Fornachon Memorial Library at infoservices@awri.com.au or phone us on (08) 8313 6600.

Abrahamse, C.E., Bartowsky, E.J. Timing of malolactic fermentation inoculation in Shiraz grape must and wine: influence on chemical composition. World Journal of Microbiology and Biotechnology DOI 10.1007/s11274-011-0814-3; 2011.

Curtin, C.D., Bellon, J.R., Bartowsky, E.J., Henschke, P.A., Chambers, P.J., Herderich, M.J., Pretorius, I.S. Harnessing AWRI’s yeast and bacterial research to shape ‘nextgen’ Chardonnay Part 2 : Influence of yeast, nutritional management and malolactic fermentation. Wine and ViticultureJjournal 26 (2) : 15-24; 2011.

King, E.S., Osidacz, P., Curtin, C., Bastion, S.E.P., Francis, I.L. Assessing desirable levels of sensory properties in Sauvignon Blanc wines – consumer preferences and contribution of key aroma compounds. Australian Journal of Grape and Wine Research 17 (2) : 169-180; 2011.

Pocock, K.F., Salazar, F.N., Waters, E.J. The effect of bentonite fining at different stages of white winemaking on protein stability. Australian Journal of Grape and Wine Research 17 (2) : 280-284; 2011.

Ristic, R., Osidacz, P., Pinchbeck, K.A., Hayasaka, Y., Fudge, A.L., Wilkinson, K.L. The effect of winemaking techniques on the intensity of smoke taint in wine. Australian Journal of Grape and Wine Research 17 (2) S29-S40; 2011.

Schmidt, A.A., Dillon, S., Kolouchova, R., Henschke, P.A., Chambers, P.J. Impacts of variations in elemental nutrient concentration of Chardonnay musts on Saccharomyces cerevisiae fermentation kinetics and wine composition. Applied Microbiology and Biotechnology DOI: 10.1007/s00253-011-3197-3; 2011.

Wilkinson, K.L., Ristic, R., Pinchbeck, K.A., Fudge, A.L., Singh, D.P., Pitt, K.M., Downey, M.O., Baldock, G.A., Hayasaka, Y., Parker, M., Herderich, M.J. Comparison of methods for the analysis of smoke related
phenols and their conjugates in grapes and wine. Australian Journal of Grape and Wine Research 17 (2) : S22-S28; 2011.

Winter, G., Van Der Westhuizen, T., Higgins, V.J., Curtin, C., Ugliano, M. Contribution of cysteine and glutathione conjugates to the formation of the volatile thiols 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA) during fermentation by Saccharomyces cerevisiae. Australian Journal of Grape and Wine Research 17 (2) : 285-290; 2011.

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.