1. Optimisation of an early harvest regime – impact on grape and wine composition and quality
Adding water to grape juice to dilute sugar and therefore alcohol is not permitted. Alternatively, early harvest of an
entire crop means the desirable ripe characters of the grapes are underdeveloped, even though sugar content is lower.
A new approach involves a sequential harvest regime, where part of the crop is harvested and fermented to a lowalcohol blending material that can legitimately be incorporated into the fermentation of the fully ripened crop
remainder. The blending material could also be dealcoholised. Few evaluations of this approach have been reported
(1) let alone from trials on a commercial scale. This method’s simplicity will increase its adoption by industry. But
first, a detailed sensory and chemical characterisation is needed for wines produced from key Australian grape
varieties, harvested at various times, subjected to different fermentation and blending options and across 2–3 vintages.
The project will be based at the University of Adelaide with likely partner organisations including the Australian
Wine Research Institute, Lowe Wines, Sainsbury’s, SARDI, Treasury Wine Estates.
Reference
(1) Kontoudakis et al (2011) Use of unripe grapes harvested during cluster thinning as a method for reducing alcohol content and
pH of wine. Aust J Grape Wine Res 17:230-8.
Contact: Dr David Jeffery, The University of Adelaide, [email protected], Ph +61 (0)8 8313 6649
2. Role of potassium in sugar unloading in grapes and berry variability (2 PhD scholarships)
Sugar accumulation in developing Shiraz grape berries mirrors the accumulation of potassium (R2 = 0.9). The slope of
the relationship is unaffected by salinity of the irrigation water or soil (1). In field trials involving Chardonnay and
Shiraz grown on own roots and on 8 different rootstocks, grape juice soluble solids (largely sucrose) and K are
positively correlated (R2 = 0.7; 2). Given this link and the fact that sucrose and K are transported in the phloem to
developing berries (3), sucrose-K co-transport at phloem loading or unloading are suggested (4). Studies in caster
bean indicate a specific K channel for sucrose unloading (5). Over 2–3 vintages, this study will examine the process
for sucrose-K transport into berries and determine if grape sugar content can be altered via vineyard K supply. The
students will be enrolled through Charles Sturt University with one being based at the CSIRO in Adelaide and the
second in Wagga Wagga. The likely partner organisations will be NSW DPI and Treasury Wine Estates.
References
(1) Walker et al (2000) Rootstock and salinity effects on rates of berry maturation, ion accumulation and colour development in
Shiraz grapes. Aust J Grape Wine Res 6:227-39 (2) Walker, Blackmore (2012) Potassium concentration and pH inter-relationships
in grape juice and wine of Chardonnay and Shiraz from a range of rootstocks in different environments. Aust J Grape Wine Res
18:183-93 (3) Lang, Thorpe (1989) Xylem, phloem and transpiration flows in a grape: application of a technique for measuring the
volume of attached fruits to high resolution using Archimedes principle. J Exp Bot 40:1069-78 (4) Lang (1983) Turgor-regulated
translocation. Plant Cell Environ 6:683-9 (5) Ache et al (2001) VFK1, a Vicia faba K+ channel involved in phloem unloading. Plant
J 27:571-80.
Contact: Prof Steve Tyerman, The University of Adelaide, [email protected], Ph +61 (0)8 8313 6663
3. Link between berry cell death and berry weight loss
Greenhouse gas emissions are predicted to increase temperature in most of Australia's grape growing regions (1).
Berry development will be brought forward to warmer months amplifying the warming effect. This will cause earlier
onset and greater severity of berry water loss (shrivel), which concentrates sugars (2). Also, cell death (CD) of the
large mesocarp cells within the berry was recently discovered (3) and found to accelerate with high temperature (4). In
Shiraz and Chardonnay CD coincides with maximum berry weight, additional softening, and the beginning of berry
shrinkage (3). We will test the hypotheses that CD contributes to berry quality and is a causative factor in shrivel
which concentrates sugar. We aim to discover details of how CD is triggered in the berry. Furthermore a rapid and
accessible technique for detection of CD in berries will be developed using impedance spectroscopy. Work will take
place over 2–3 vintages as well as use glasshouse vines. The project will be based at the University of Adelaide with
likely partner organisations including Charles Sturt University and NSW DPI.
References
(1) Webb et al (2007) Modelled impact of future climate change on the phenology of winegrapes in Australia. Aust J Grape Wine
Res 13:165–75 (2) Greer, Rogiers (2009) Water flux of Vitis vinifera L. cv. Shiraz bunches throughout development and in relation
to late-season weight loss. Am J Enol Vitic 60:155–63 (3) Tilbrook, Tyerman (2008) Cell death in grape berries varietal differences
linked to xylem pressure and berry weight loss. Funct Plant Biol 35:173-84.
Contact: Prof Steve Tyerman, The University of Adelaide, [email protected], Ph +61 (0)8 8313 6663
4. The biochemical response of grapevines to smoke exposure
Global warming is increasing the frequency of heatwaves and the incidence of bushfires (1,2). Fires proximal to
vineyards can dramatically affect wine even where vines are not burnt. Grapes from smoke-exposed vines are tainted
and so too are the resulting wines, making them unsaleable, and a significant challenge to grapegrower and
winemaker viability in fire-prone areas. This project builds on our pioneering work on the topic (3,4) and will
investigate the biochemical responses of grapevines to smoke exposure, particularly the accumulation of smokederived volatiles in glycoconjugate forms. Field and glasshouse vines will be treated over 1 or more vintages, with the
latter to 2 years involving lab-based work. New knowledge will aid development of practical solutions for eliminating
smoke taint in wine. The project will be based at the University of Adelaide with likely partner organisations
including the Australian Wine Research Institute and Memstar.
References
(1) Overpeck et al (1990) Climate-induced changes in forest disturbance and vegetation. Nature 343:51–3 (2) Mira de Orduña
(2010) Climate change associated effects on grape and wine quality and production. Food Res Internat 43:1844–55 (3) Kennison et
al (2007) Smoke-derived taint in wine: effect of postharvest smoke exposure of grapes on the chemical composition and sensory
characteristics of wine. J Ag Food Chem 55:10897–901 (4) Ristic et al (2011) The effect of winemaking techniques on the intensity
of smoke taint in wine. Aust J Grape Wine Res 17:S29–S40.
Contact: Dr Kerry Wilkinson, The University of Adelaide, [email protected], Ph +61 (0)8 8313 7360
5. Using alternate fermentation microbes to reduce ethanol yield or enhance aroma
Saccharomyces is the preferred inoculum for winemaking due to its superior ethanol tolerance and resulting
dominance of mixed population fermentations (1,2). But other microbes, previously seen as spoilage organisms, are
now credited as legitimate contributors to wine quality (3,4), partly due to their converting less sugar to ethanol and
more to other metabolites (4). Such microbes are now used as pure culture inocula, albeit Saccharomyces still being
needed to complete fermentation. Interestingly, mixed cultures produce a different profile of metabolites and ethanol
yields, than do pure cultures - likely due to metabolite sharing (2). Signalling between the populations is also possible.
This project will determine metabolite production of pure (yr 1) vs mixed cultures (yr 2) to help discover the nature of
the interaction between yeasts. Yields of interest (eg low ethanol or high sensory compounds) will help identify
strains and inoculation regimes of potential sensory importance (yr 3). Our recent pioneering work using quantum
dots to mark and follow strains in mixed culture will be invaluable. The project will be based at the University of
Adelaide with likely partner organisations including the Laffort Oenologie, Lowe Wines and Treasury Wine Estates.
References
(1) Heard, Fleet (1988) The effects of temperature and pH on the growth of yeast species during the fermentation of grape juice. J Appl
Microbiol 65:23-8 (2) Fleet (2003) Yeast interactions and wine flavour. Internat J Food Microbiol 86:11–22 (3) Jolly et al (2006) The role
and use of non-Saccharomyces yeasts in wine production. S Afr J Enol Vitic 27:15-39 (4) Soden et al (2000) Effects of co-fermentation
with Candida stellata and Saccharomyces cerevisiae on the aroma and composition of Chardonnay wine. Aust J Grape Wine Res 6:21–30
(34) Ciani, Maccarelli (1998) Oenological properties of non-Saccharomyces yeasts associated with wine-making.
World J Microbiol Biotech 14:199-203.
Contact: Prof Vladimir Jiranek, The University of Adelaide, [email protected], Ph +61 (0)8 8313
6651
6. Removing excess sugar in grapes via microbial synthesis of inert carbon sink compounds
Cyclodextrins are non-toxic, naturally-occurring, cyclic oligosaccharides formed by the action of certain
microorganisms on starch (1). The enzyme responsible for their formation, cyclodextrin glycosyltransferase,
(CGTase) has been immobilised on solid supports, and shown to still convert glucose to cyclodextrins (2). This
project will evaluate such immobilised enzymes (yr 1) as ‘dip’ catalysts to sequester free grape glucose into large
cyclodextrins that are non-fermentable and sensorially neutral (yr 2). The fate of carbon from metabolised sugars,
steps to remove the cyclodextrins and the oenological acceptability of the enzyme products will be determined using
suitable chromatographic and sensory techniques (yr 2–3). The project will be based at the University of Adelaide
with likely partner organisations including the Australian Wine Research Institute, Laffort Oenologie and
BioInnovation SA.
References
(1) Del Valle (2004) Cyclodextrins and their uses: a review. Process Biochem 39:1033-46 (2) Svensson, Adlercreutz (2011)
Immobilisation of CGTase for continuous production of long-carbohydrate-chain alkyl glycosides. J Molec Cat B:Enz 69:147-5.
Contact: Prof Dennis Taylor, The University of Adelaide, [email protected], Ph +61 (0)8 8313 7239
7. Efficiency and sensory outcomes of spontaneous fermentations of high sugar-content grapes
High sugar fermentations represent a highly stressful environment for yeast - one of high initial osmolarity followed
by high final ethanol content (1). While Saccharomyces is generally tolerant to such conditions, these fermentations
are slow and prone to premature arrest and spoilage, which detract from winery efficiency and wine quality. When
spontaneous fermentations are employed that rely on non-Saccharomyces yeasts that are far less alcohol tolerant, it is
certain that high sugar fermentations will change the progression and performance of individual species and thereby
the composition of the wine. This project extends our current work on Saccharomyces yeast in high stress
environments to define this unexplored aspect of non-Saccharomyces yeast fermentations. New strains will be isolated
(yr 1) and characterised (yr 2) to defined strategies (yr 3) for ensuring superior fermentation outcomes. The project
will be based at the University of Adelaide with likely partner organisations including the Australian Wine Research
Institute and Laffort Oenologie.
Reference
(1) Querol, Bond (2009) The complex and dynamic genomes of industrial yeasts. FEMS Microbiol Lett 293:1-10.
Contact: Prof Vladimir Jiranek, The University of Adelaide, [email protected], Ph +61 (0)8 8313
6651
8. Selective and deliberate use of winemaking supplements to modulate sensory properties in wine
Numerous ‘natural’ extracts (ex yeast or plants) are used to augment wine sensory properties (1-4). Oak wood in the
form of barrels is also used to strongly influence wine quality by enhancing colour, stability and sensory properties,
but is costly ($800/unit) and labour intensive. Oak products (incl. chips, powders & tannins) are more cost effective
but their use is less well defined. Apart from the above adding to wine sensory attributes, the use of food grade
sweetness suppressants such as lactisole (5) in wine is an innovative approach to masking sugar in part-fermented (ie
lower-alcohol) wines. The project will use comprehensive chemical and sensory analysis (yr 1–2) to produce new
knowledge about the most effective timing, combinations and doses of additives to manipulate mouthfeel, sweetness
and wine complexity, specifically and predictably (yr 2–3) so as to improve quality and profitability. Key subjects will
be commodity wines and/or wines with reduced ethanol content. The project will be based at the University of
Adelaide with likely partner organisations including Laffort Oenologie and Tarac Technologies.
References
(1) Harbertson et al (2012) Impact of exogenous tannin additions on wine chemistry and wine sensory character. Food Chem
131:999-1008 (2) Marchal, Jeandet (2009) Use of enological additives for colloid and tartrate salt stabilization in white wines and
for improvement of sparkling wine foaming properties. In Wine Chemistry and Biochemistry; Moreno-Arribas & Polo; Eds
Springer New York 127-58 (3) Gómez García-Carpintero et al (2012) Impact of alternative technique to ageing using oak chips in
alcoholic or in malolactic fermentation on volatile and sensory composition of red wines. Food Chem 134:851-63 (4) Del BarrioGalán et al (2011) Techniques for improving or replacing ageing on lees of oak aged red wines: the effects on polysaccharides and
the phenolic composition. Food Chem 127:528-40 (5) Schiffman et al (1999) Selective inhibition of sweetness by the sodium salt
of 2-(4-methoxyphenoxy) propanoic acid. Chem Senses 24:439-47.
Contact: Dr Kerry Wilkinson, The University of Adelaide, [email protected], Ph +61 (0)8 8313 7360
or Prof Vladimir Jiranek, The University of Adelaide, [email protected], Ph + 61(0)8 8313 6651
9. Getting alcohol content right: the compositional and sensory basis of the alcohol ‘sweetspot’
Humans typically have difficulty distinguishing differences of less than 1-2% ABV as in 14% vs 15.5% ABV (1).
This means that the alcohol in a wine at 16% ABV can be reduced below a critical taxation threshold without adverse
sensory effects for consumers. A wine may actually appear better with less alcohol, but the point where the so-called
‘alcohol sweetspot’ occurs depends on many ill-defined factors. Altering alcohol content doesn’t just alter the
perception of alcohol. Many wine components interact in their impact on our senses (eg sugar and acid), and alcohol
itself imparts ‘heat’, sweetness, and affects the volatility (2), and thus, perception of other odorants in wine (3). This
project will examine dealcoholised or alcohol-fortified wines to determine the alcohol sweetspot (yr 1) and then, via a
combination of descriptive sensory analysis by trained panellists together with comprehensive chemical analysis of
wine aroma compounds, define this phenomenon in sensory and chemical terms (yr 2–3). This will provide clear
guidelines for winemakers to manage alcohol in wine. The project will be based at the University of Adelaide with
likely partner organisations including Treasury Wine Estates and Memstar.
References
(1) Yu, Pickering (2008) Ethanol difference threshold in wine and the influence of mode of evaluation and wine style. Am J Enol Vitic
59:146-52 (2) Robinson et al (2009) Interactions between wine volatile compounds and grape and wine matrix components influence
aroma compound headspace partitioning. J Agric Food Chem 57:10313-22 (3) Goldner et al (2009) Effect of ethanol level in the
perception of aroma attributes and the detection of volatile compounds in red wine. J Sens Stud 24:243-57.
Contact: Dr Kerry Wilkinson, The University of Adelaide, [email protected], Ph +61 (0)8 8313 7360
or Prof Vladimir Jiranek, The University of Adelaide, [email protected], Ph + 61(0)8 8313 6651
10. Controlling unripe or ‘green’ characters in early harvest grapes using Molecularly Imprinted Polymers
(MIPs) or specific microbial enzymes to eliminate methoxypyrazines
Methoxypyrazines (MPs) such as 3-isobutyl-2-methoxypyrazine (IBMP) are potent odorants, perceptible in wine at
nanograms/L. MPs can add complexity but their ‘green’ (vegetative or herbaceous) aromas at higher concentrations
are undesirable. MPs are produced early in development of some grape varieties and are largely unaffected by
winemaking practices. Thus harvesting grapes early (eg to keep sugar and potential alcohol low) runs the risk of
producing wines that smell green and unripe. Methods for eliminating MPs post-harvest are needed. One approach
involves a matrix such as a Molecularly Imprinted Polymer (MIP) (1). The functional polymer is templated with the
target compound, in this case IBMP, to provide recognition sites (2) that selectively bind and removed IBMP from
juice or wine (yr 1–2). Alternatively microbial strains or enzymes capable of MP degradation will be sought (yr 1).
Such microbes would transform MPs into oxidised or conjugated forms (3) devoid of negative aroma contributions or
with higher detection thresholds. Their effectiveness alone or in parallel with MIPs will be assessed (yr 2–3). The
project will be based at the University of Adelaide with likely partner organisations including the Australian Wine
Research Institute, BioInnovation SA and Laffort Oenologie.
References
(1) Kelm (2012) Removing compounds from wine. US Pat 2012/0196024 A1 (2) Alexander et al (2006) Molecular imprinting
science and technology: a survey of the literature for the years up to and including 2003. J Molec Recog 19:106-80 (3) Rajini et al
(2011) Microbial metabolism of pyrazines. Crit Rev Microbiol 37:99-112.
Contacts: Prof Dennis Taylor, The University of Adelaide, [email protected], Ph +61 (0)8 8313 7239
or Prof Vladimir Jiranek, The University of Adelaide, [email protected], Ph +61 (0)8 8313 6651
11. Consumer and market barriers to acceptance of wines of reduced alcohol content
Winemakers are interested in methods to reduce wine alcohol content that minimally impact the enjoyment of the
wine. This latter point is critical, since consumers are clearly interested in product taste when choosing an alcoholic
beverage (1). As such, a consumer study will be undertaken to investigate the acceptability of reduced alcohol wines
produced through other projects in the Centre. As well as sensory assessment using the 9-point Likert scales (2),
panellists (local and in international markets) will be surveyed for their perceptions, attitudes towards and unmet
demand for reduced-alcohol wines (yr 1–2). The findings and sensory panel will underpin other projects in the Centre
and also will help guide development of new products of tailored alcohol and sensory attributes (yr 2–3). The project
will be based at the University of Adelaide with likely partner organisation being Sainsbury’s (UK).
References
(1) Wright et al (2008) Beer consumers' perceptions of the health aspects of alcoholic beverages. J Food Sci 73:H12-7 (2) Lawless,
Heymann (2010) Sensory Evaluation of Food: Principles and Practices, Lawless HT & Heymann H Eds, Springer, New York
Contact: Dr Roberta Veale, The University of Adelaide, [email protected], Ph +61 404833924