Shining some light on wine innovation

AWRI

REPORT

Shining some light on wine innovation Managing Director, Sakkie Pretorius.

Novel applications of spectral analysis

developed by The Australian Wine Research Institute

Peter W. Godden, Daniel Cozzolino, Paul A. Smith, Bob G. Dambergs, Wies U. Cynkar, Nevil Shah, Ella M.C. Robinson and Isak S. Pretorius The Australian Wine Research Institute, PO Box 197, Glen Osmond (Adelaide), South Australia 5064, Australia

The Australian Wine Research Institute (AWRI) was a pioneer in the use of spectral analytical techniques for grapes and wines, and continues to be the world-leader in the development of analytical techniques in this exciting area. Novel, application-ready uses of spectroscopy developed at the AWRI are being made available to Australian wine producers, and three of them are discussed here: the AWRI tannin web portal; BevScan (developed in conjunction with Jeffress Engineering and CAMO software); and the PinotG Style Spectrum. These tools not only have the capacity to add value to the entire production chain, from the vineyard to the winery, and through packaged wine distribution to its point of sale, but are excellent examples of dividends accruing from the Australian grape and wine sector’s long-term commitment to R&D investment.

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he Australian wine industry’s capacity to produce wines that over-delivered on the expectations of wine consumers has been a major factor in the success it has enjoyed over the last two decades. In recent years, however, several factors including increasing international competition and unfavourable exchange rates have combined to blunt that success, especially in the commodity wine sector. There now appears to be a growing acceptance that greater emphasis should be placed on communicating, particularly in overseas markets, Australia’s well established culture of fine wine production, and on building our share of those markets with higher price-pointed wines yielding greater profit margins. However, up-scaling to produce such wines with maximum efficiency and in sufficient quantities presents many challenges. These include identifying market segments in which Australia has the potential to compete, and then building the capacity within our industry to produce the wines that deliver on the expectations of consumers in those segments. Additionally, the ability to better communicate wine style

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differences to consumers would enable more effective differentiation of the Australian wine offering, allowing us to build greater market loyalty and also meet consumer expectations in the long term. In order to achieve these goals, an ability to objectively define wine style ‘targets’ would be highly desirable, as would the ability to monitor changes and variability in wines pre- and postpackaging, through to point-of-sale. In such a scenario, the targets, which could be considered analogous to ‘fingerprints’, could be set by sensory profiling, and spectroscopic analytical techniques would then be used to assess the closeness of a wine to the desired target, and any changes that might occur pre- or postpackaging which move a wine further from or towards that original target. Further, the same concept of ‘fingerprinting’ could be extended to grapes, allowing the further development of market structures that properly reward the production of grapes, thereby most readily enabling the wine style targets to be met. The availability of analytical techniques to ‘fingerprint’ grapes and wines would

potentially re-define the way we think about grape and wine quality and quality control, especially if coupled with rapid and inexpensive techniques measuring specific constituents of grapes and wines, which are already known to relate to quality. Further, the use of such fingerprints as targets of desired wine style could potentially revolutionise wine production, through the ability to assess which batches of grapes, and which winemaking techniques most reliably produce wines that hit the target. Demonstrating the value of investment in AWRI’s pioneering research and thought leadership

So far, some readers might be thinking that the availability of such techniques is either ‘pie-in-the-sky’, or a part of a distant ‘brave new world’ that they hope they will never have to face. However, many will no doubt be considering the boundless opportunities if tools, which made such wine and grape ‘fingerprinting’ a reality, were available. In fact, many steps along the path to make such fingerprinting a reality have already been taken at the AWRI over the past 13 years

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by its near infrared (NIR)/Rapid Analytical Methods team. During that time, a world-leading body of knowledge on the use of spectroscopy in grape and wine analysis has been built from what was pioneering research in 1997. The scientists who have built this capability now form an integral part of the AWRI’s Industry Applications Group: the ‘D’ component of the AWRI’s unique R,D,E&C (Research, Development, Extension and Commercial) business model. The Industry Applications Group was established in 2008, and sought from the outset to develop, as part of its project portfolio, novel, industry-ready applications to ensure that its spectroscopy expertise became better adopted by grape and wine producers. As a result, three novel spectroscopy-based technologies – the AWRI tannin web portal, BevScan and the PinotG Style Spectrum, have either reached the final proof-of-principle phase of their development with industry partners, or have already been made available to the Australian grape and wine sector. Most existing analytical methods are both time consuming and costly, relying on well-equipped central laboratories and large numbers of qualified staff. However, spectroscopic techniques based on near infrared (NIR), mid-infrared (MIR) and the ultraviolet (UV) or visible (VIS)regions of the electromagnetic spectrum, have several advantages such as: short analysis time; little or no sample preparation; the ability to measure several variables simultaneously (thus creating a ‘fingerprint’); and the potential for in-field or on-site use (i.e., in the vineyard, on mechanical harvesters, at the winery weighbridge, and potentially on the winery floor). A brief history of NIR spectroscopy at the AWRI

Near infrared spectroscopy (NIR) has gained increasing acceptance as an analytical tool in the wine industry since the late 1980s. The most common application of NIR has been for the determination of alcohol in wine (Baumgarten 1987), and the AWRI Commercial Services (formerly the Analytical Service) was one of the first wine laboratories in Australia to purchase and use a fixed-filter NIR instrument for that purpose.

The potential of further applications of the technology in the wine industry has been the subject of research at AWRI since 1997. Mark Gishen and Dr Bob Dambergs first discussed their common view of the potential of the technique when they met at the 7th International NIR Conference in Lorne, Victoria, in April 1994. Mark Gishen joined the AWRI later that year and set in motion collaborations to further investigate the potential of NIR in grape and wine analysis. Staff members involved in the AWRI grape flavour research project were already aware of the use of NIR in other agricultural industries, particularly for grains where it is used as a means of rapidly evaluating grain composition and quality. At about the same time, interest in the Australian grape and wine sector in using berry colour as a means of assessing grape quality was growing. The traditional method of colour analysis was quite laborious and time consuming and was, therefore, an ideal candidate for replacement by a rapid technique such as NIR. Via collaborations among several project teams within the AWRI, and also with a large wine production company, grape samples that had been analysed for a range of compositional variables, including colour, were obtained for scanning with NIR. At the time, the AWRI did not have a scanning instrument, but secured the assistance and access to instrumentation of other researchers on the Waite Campus of the University of Adelaide, and the trials proceeded in late 1997. The results of those preliminary experiments were promising and were later reported in several reviews (Gishen et al. 2005, Cozzolino et al. 2006). It was considered that the technique might be applicable to the determination of methanol in grape spirit, as well as the determination of the pH, sugar, nitrogen, total anthocyanin (colour) and glycosylglucose (GG) concentrations in grapes. It was, therefore, decided that a dedicated project would be developed to further investigate the potential applications of NIR technology (Gishen et al. 2005). The initial project proposal was developed with funding sought from the Grape and Wine Research and Development Corporation (GWRDC). Collaboration was established through

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Dambergs, then technical services manager with the BRL Hardy Wine Company (now Constellation Wines Australia). BRL Hardy purchased a FOSS NIRSystem6500 instrument in August 1998 and a technical assistant was employed to assist in the research. Work performed during that period included: a review of the literature, development of a calibration for methanol in spirits, assessment of a calibration for GG (a possible indicator of flavour) in white and red grapes, development of a calibration for grape colour, pH and total soluble solids (°Brix) in red grape samples; and some preliminary work on scanning wines for which data on wine quality were available. Throughout the following year, the collaboration was extended to include several other larger wine producers, including Yalumba, Orlando, McWilliam’s and Foster’s and, after obtaining funding for the purchase of its own FOSS NIRSystems6500 instrument, the project became established as a significant part of the research effort at the AWRI. Evaluation of NIR for the analysis of compositional variables in both grapes and wines continued to show great potential, in particular, the development of the calibrations for colour of red grapes (Cozzolino et al. 2006). In fact, the technique appeared to offer significant potential benefits and the project was, therefore, included as one of the main thrusts of the program proposed in the successful bid for the second round funding of the Cooperative Research Centre for Viticulture (CRCV). As a result of that additional funding, the project accelerated, initially with the appointment of a post-doctoral research fellow, Dr Michael Esler (February 2000 to June 2002), and later Dr Daniel Cozzolino (June 2002 to present), who is the team leader. The outcomes of that research project are almost certain to greatly improve the capacity of grapegrowers and wine producers to assess grapes and wines for parameters relevant to wine style and end-use. Additionally, producers will benef it through applications of the technique in the quality assurance (QC) of bottled wine through distribution, and the communication of wine styles to consumers at the point of sale. 47

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Figure 1. The AWRI tannin web portal.

Highlights of the AWRI’s NIR research 1998-2010

• the use of NIR spectroscopy for quantification of methanol in spirits (Dambergs et al. 2002) • the use of NIR spectroscopy for pred ict ing g rape qu a lit y composition – colour, total soluble solids and pH – of red grapes • the use of NIR spectroscopy to measure other parameters in grapes includ ing GG, phenol ic compounds (e.g., tannins), and determination of the extent of botrytis infection • the use of NIR spectroscopy for monitoring red wine fermentations for the extraction and evolution of some critical phenolics, including malvidin 3-glucoside, pigmented polymers and tannins • the use of spectroscopy to predict sensory attributes in wine • the proof of principle on the use of spectroscopy to discriminate between winegrape varieties and regions • the development of MIR spectroscopy to measure wine parameters (ethanol, pH, glucose a nd fructose) a nd juice compositional variables (yeast 48

assimilable nitrogen [ YA N], soluble solids, pH) • the proof of concept of an NIR method to measure wines nondestructively in bottle, which later become a reality with the development of a dedicated instrument for in-bottle analysis (namely BevScan) (Cozzolino et al. 2007). The AWRI tannin web portal

The AWRI significantly simplified and optimised the measurement of grape and wine tannin by developing the Methyl Cellulose Precipitation (MCP) assay (Herderich and Smith 2005, Sarneckis et al. 2006, Mercurio et al. 2007). The MCP tannin assay was a great leap forward, but its uptake by industry appeared patchy. While the assay is relatively simple, feedback received from producers at AWRI roadshows indicated that many still considered it too timeconsuming a laboratory method. For the assay to be widely adopted, especially during the intense vintage period when there is the greatest opportunity to influence tannin concentration in wine and when, therefore, tannin measurement has great potential value, a simpler method would be required.

An industry survey to gauge interest in measuring tannin

Based on that anecdotal feedback, an industry survey was conducted in order to properly gauge industry use of the MCP assay, and interest in tannin measurement generally. The questionnaire was distributed to Australian-based members of the Interwinery Analysis Group (www. interwinery.com.au), and 82% of respondents indicated interest in measuring tannin via a web-based interactive tool, although only 15% were currently measuring tannin in either grapes or wines. Common reasons stated for not measuring tannin were: ‘not a priority’, ‘takes too long’ and ‘not sure how to use the results’. Respondents were interested in measuring tannin in wine (90%), ferments (72%) and grapes (60%). When asked how they would utilise the tannin information, the most frequent responses were: monitoring tannin extraction during ferment (73%); monitoring tannin additions (53%); benchmarking their product (56%); and blending decisions (51%). Also, the industry survey revealed that of the laboratories that had UV-Vis spectrophotometers, only half had scanning instruments, leaving half realistically only able to measure a small number of wavelengths.


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Could the AWRI develop a spectral calibration for tannin and could such a calibration be transferred to industry laboratories?

In order to respond to this clearly-stated industry need, the AW R I ’s R a pid Analytical Methods team set to work and successfully built a UV spectral calibration using the MCP ‘reference method’ – a significant achievement in its own right. The next major hurdle was to assess the transferability of the calibration (which had been established on a reference instrument at the AWRI) to other instruments in industry laboratories. A ‘proof of concept’ study was performed with a small number of industry laboratories. To assist with calibration transfer, the method was simplified to the point where it utilises only a small number of wavelengths, making the

calibration algorithm, instrument matching and referencing simpler. The study demonstrated that after slope and bias adjustments, and by using reference standard solutions, tannin results from

Figure 2. The BevScan in-bottle NIR spectrophotometer. w i n e i n d u s t r y j o u r n a l > V OL 2 5 NO 3 > M AY/JUNE 2 0 10 > w w w.w i n e b i z .c o m . a u

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the industry instruments showed no statistical differences to each other. Also, the results were not significantly different to the MCP tannin assay reference method performed at the AWRI. Web-based interface – the AWRI tannin web portal

The UV tannin calibration has now been made available to all Australian wine producers through a simple-to-use web-based interface called the AWRI tannin web portal (Figure 1). Data are uploaded using spreadsheets, and a web-based laboratory information management system (LIMS) allows the uploaded data to be processed using calibrations that are individualised (using slope and bias data) to a particular winery instrument. The calibration is centrally maintained and as data are generated they are added to the existing database, which currently contains results from more than 3000 red wine samples. The database is searchable by all clients, while confidentiality regarding the identity of users and of their data is strictly maintained. The database is searchable by vintage, variety and by Australian region, and allows users to gain a better understanding of the context and relevance of their results. A reference standard measured on a client instrument every time data are uploaded allows quality control monitoring of the instruments. The AWRI tannin web portal is now available for use by all Australian wine producers and has been used by several leading companies during the 2010 vintage. It is possible to track tannin concentrations in wines during fermentation and during blending. The portal not only simplifies tannin analysis for anyone who has access to a UV-Vis spectrophotometer, but is backed by a large database of tannin results. This allows the results of new samples entered into the portal to be reported in context of other results in the database for the same region, grape variety or vintage. Readers wishing to obtain more information regarding use of the portal should contact Dr Paul Smith or Neil Scrimgeour on +618 8303 6600, or email [email protected] 49

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BevScan

BevScan is the world’s first nondestructive, in-bottle analyser, the development of which has been a three-way collaboration between the AWRI, Jeffress Engineering, and CAMO software (Figure 2, see page 49). BevScan uses NIR to record spectra of wines in-bottle, through the glass, without the need to open the bottle. However, it can also be used as a standard NIR spectrophotometer by scanning samples in standard laboratory cuvettes instead of in-bottle. The AWRI has been developing the concept of non-destructive measurement of wine in-bottle for more than a decade. Data relating to the development of optical density at a wavelength of 420 (OD420) in a Semillon wine sealed with 14 different closures were generated by scanning the same bottles at intervals over time using, at that stage, a modified UV-Vis spectrophotometer (Godden et al. 2001). Over a period of several years, the AWRI had assessed a number of prototype devices from around the world for their potential use as hardware-platforms for applications of NIR technology in vineyard and winery settings. The first formal collaboration, however, actually came from very close to home, with a small Adelaide-based engineering company, Jeffress Engineering. The software that drives the analysis of the spectra collection was developed by a Norwegian company, CAMO software, which produces The Unscrambler software package – used widely in spectral analysis, including at the AWRI. The AWRI purchased two BevScans in late 2009 and, more recently, completed an exhaustive evaluation of the two instruments. Very little variability was identified between them. The next phase is to develop a range of wine industry applications for BevScan. Sorting bottles for levels of oxidation is an obvious application, which has already been used by industry. Proof-of-principle trials are also commencing to investigate potential applications of BevScan in wine authenticity testing; the monitoring of fermentation in bottle-fermented sparkling wines; tracking potential heat effects during transport; and wine traceability through transport and distribution. The AWRI Commercial Services now offers fee-for-service consulting with BevScan, and is working with a number of 50

wine producers on novel and proprietary applications of the technology – contact Dr Vince O’Brien on email: Vince.O’Brien@ awri.com.au, or [email protected] Pinot G Style Spectrum

The PinotG Style Spectrum is intended as a tool to help communicate Pinot Grigio/ Pinot Gris wine style to the market. Pinot Grigio and Pinot Gris are two names for the same grape variety. Traditionally in Europe, two styles of wine have been produced, with those in northern Italy labelled Pinot Grigio having a ‘lighter’ and ‘crisper’ texture, and those in Alsace labelled Pinot Gris being ‘richer’ and more ‘luscious’. In Australia, both names are used and a wide range of styles is produced. However, the style of wine inside the bottle does not necessarily reflect the varietal name on the label. In October 2007, the AWRI was approached by a leading wine producer concerned by confusion in the marketplace regarding the use of the two names for the same grape variety. The confusion was thought to be inhibiting the understanding and consumer acceptance of wine made from this variety. The AWRI was asked if it could apply laboratory analysis to develop objective parameters to define ‘what constitutes a Grigio’, and ‘what constitutes a Gris’, in terms of wine style. The AWRI approach has been to combine its unique range of expertise across a range of science disciplines, in this case, spectral analysis, chemical analysis, sensory analysis and chemometrics. Trained sensory panels, including a large number of winemakers, have tasted a range of Pinot Grigio and Pinot Gris wines over a period of two years, and the wines were also scanned using MIR spectroscopy (thus creating a spectral ‘fingerprint’ of each wine). The data collected from the sensory evaluation and MIR scans are being used to build a calibration that correlates the sensory panel ratings for the wines’ Grigio-ness to Gris-ness with the MIR spectral ‘fingerprints’ of the wines. As more wines are subjected to sensory analysis and are scanned, and the resulting data added to the calibration, the model is expected to strengthen, thus in future a wine’s position on the scale may be determined by a spectral scan alone. Importantly, the ‘wine fingerprinting’ technique that has been used for this project has possible applications beyond the PinotG Style Spectrum labelling tool. If

suitable calibrations were built, winemakers could use spectral fingerprinting to tailor wines to fit on various points of the Spectrum, by scanning wines during production and assessing the propensity of different winemaking techniques to create wines that are considered more Grigio-like or Gris-like. Further, there is potential for the same technique to be used with other varieties to set the wine style targets discussed in the introduction, and then to assess whether various winemaking techniques are more or less likely to produce wines that hit the style target. Acknowledgements

The Australian Wine Research Institute, a member of the Wine Innovation Cluster in Adelaide, is supported by Australian grapegrowers and winemakers through their investment body, the Grape and Wine Research and Development Corporation (GWRDC), with matching funding from the Australian Government. The authors wish to thank Rae Blair for her editorial assistance. References Baumgarten, G.F. (1987) The determination of alcohol in wines by means of near infrared technology. S. Afr. J. Enol. Vitic., 8: 75-77. Cozzolino, D.; Cynkar, W.U.; Dambergs, R.G. and Gishen, M. (2006) Analysis of grape and wine by near infrared spectroscopy – a review. J. Near Infrared Spectrosc., 14: 279-289. Cozzolino, D.; Kwiatkowski, M.J.; Waters, E.J. and Gishen, M. (2007) A feasibility study on the use of visible and short wavelengths in the near infrared region for the non-destructive measurement of wine composition. Analyt. Bioanalyt. Chem., 387: 2289-2295. Dambergs, R.G.; Kambouris, A.; Francis, I.L.; Gishen, M. (2002) Rapid analysis of methanol in grape derived distillation products using near infrared transmission spectroscopy. J. Ag. Food Chem., 50: 3079–3084. Godden, P.W.; Francis, I.L;, Field, J.; Gishen, M.; Coulter, A.D.; Valente, P.; Høj, P.B. and Robinson, E.M.C. (2001) Wine bottle closures. Physical characteristics and effect on composition and sensory properties of a Semillon wine. 1. Performance up to 20 months post bottling. Aust. J. Grape Wine Res., 11: 64-105. Gishen, M.; Cozzolino, D. and Dambergs, R.G. (2005) Grape and wine analysis in the Australian wine industry — enhancing the power of spectroscopy with chemometrics. Aust. J. Grape Wine Res., 11: 296-305. Herderich, M.J.; Smith, P.A. (2005) Analysis of grape and wine tannins: methods, applications and challenges. Aust. J. Grape Wine Res. 11: 205 – 214. Mercurio, M.D.; Dambergs, R.G.; Herderich, M.J. and Smith, P.A. (2007) High throughput analysis of red wine and grape phenolics – adaptation and validation of methyl cellulose precipitable tannin assay and modified somers color assay to a rapid 96 well plate format. Journal of Agricultural and Food Chemistry, 55 (12):4651-4657. Sarneckis, C.J.; Dambergs, R.G.; Jones, P.; Mercurio, M.; Herderich, M.J. and Smith, P.A. (2006) Quantification of condensed tannins by precipitation with methyl cellulose: development and validation of an optimised tool for grape and wine analysis. Aust. J. Grape Wine Res., 12: 39-49.
