Search

Background: The current method employed by industry for tissue analysis to determine grapevine nitrogen (N) status is expensive and time intensive. Aims: This study explored the use of proximal sensors and Fourier transform near infrared spectroscopy (FT-NIRS) to predict vine (Vitis vinifera L.) canopy N status over two growing seasons in Southern Tasmania, Australia. Methods: The GreenSeeker, Crop Circle ACS-430 and SPAD-502 proximal sensors were used to measure vine canopies (cv. Pinot Noir and Chardonnay) at three sampling dates (January, February, March) in the 2017/18 growing season, and two (December & February) in the 2018/19 growing season. For 12 replicates consisting of 5 vines each, a 30-leaf sample was taken for FT-NIRS and elemental analysis on dried, ground leaf samples. In addition, measurements with a portable FT-NIRS were taken on fresh leaf samples (2018/19). All measurements were correlated with leaf N concentration (%) determined via elemental analysis. Results: The reliability of the proximal sensors to predict vine N content was dependent on the vine variety and sampling time. FT-NIRS demonstrated a strong ability to predict vine N concentration independent of season, sampling time and variety. The benchtop FT-NIRS showed the strongest predictability over both seasons (r2 = 0.94), yet the portable FT-NIRS also showed potential (r2 = 0.76). Conclusion: Further investigation of portable FT-NIRS technology is necessary to provide a robust model for non-destructive vine N determination in the field.

Pinot noir fruit is often relatively low in the phenolics important for wine mouthfeel and color stabilization. Previous research has shown that leaf removal can influence the concentration and composition of Pinot noir fruit phenolics, but it is not clear to what extent these effects on grape composition are carried through the winemaking process. A novel thermal treatment, ‘Controlled Phenolic Release’ (CPR), has been demonstrated effective for increasing the phenolic concentration of Pinot noir wines, but there is currently limited information on the interaction between this process and viticultural practices. CPR is microwave heating of grape must to hasten phenolic extraction. This study applied viticultural treatments to Pinot noir (no leaf removal; leaf removal at post-flowering and pre-veraison) in two commercial vineyards (A and B), and winemaking treatments in replicated microvinifications (control; CPR with skin contact; CPR with early pressing) were applied to fruit from vineyard A. Effects on grape and wine phenolics were examined using UV-visible spectrophotometry. Wine tannin composition and polymerization were assayed by methyl cellulose precipitation (MCPT) and high-performance liquid chromatography (HPLC). Viticultural treatments applied produced significant effects in vineyard A but not vineyard B. Winemaking treatments impacted the concentration of phenolics in wines, but there was no interaction between viticultural and winemaking treatments; effects were additive. Of scientific and practical significance was the finding that grape phenolic concentration determined from homogenate extractions of fruit did not reliably predict Pinot noir wine phenolics. Further, in wines, variation in tannin composition, the extent of tannin polymerization and tannin size was found between treatments. The novel findings here are that the viticultural treatment and the winemaking treatments were both significant and, being independent of each other, offered two separate ways to adjust phenolics in Pinot noir wine. Viticultural and winemaking treatments were also shown to affect tannin composition, with potential mouthfeel and color stability implications.

Fungal diseases such as powdery mildew and bunch rots reduce yield and quality of grapes and affect chemical and sensory properties of wine. The effects of powdery mildew, downy mildew, botrytis bunch rot, and ripe rot on grape and wine quality are reviewed. Approaches to detection and quantification of fungal contamination are examined, including enzyme, immunological and DNA assays and spectroscopy. Such approaches offer efficient and or objective means of quantifying fungal contamination in the vineyard and at the winery to facilitate quality control and decisions about use of grapes. Alternatives to conventional fungicides for disease management and their effects on quality are examined also.

Background and Aims Haze formation in white wine is caused by protein aggregation and can be influenced by many other wine components. This study investigated the impact of wine matrix composition on haze formation in 60 white wines to assess the feasibility of predicting haze by measuring selected wine components. Methods and Results Sixteen wine matrix components previously shown to influence wine haze in model and reconstitution studies were analysed in a range of white wines and compared to the amount of haze formed in a heat test. Protein concentration and electrical conductivity were the only components that significantly (P

Varietal base ciders were produced from three varieties of dessert apples (‘Pink Lady®’, ‘Royal Gala’ and ‘Red Delicious’) at pre-commercial, commercial and post-commercial harvest timings. Rapid analytical methods were used to categorise the base ciders, and data analysed using principal component analysis (PCA). The titratable acidity of apple must was significantly higher for the pre-commercial harvest fruit for both the ‘Royal Gala’ and ‘Red Delicious’ varieties. The base cider phenolic content was highest in the pre-commercial harvest fruit for all varieties. ‘Red Delicious’ had the highest total phenolics as determined by spectral analysis and supported by the classification provided by the PCA analysis. The spectral fingerprints of the ciders showed two main peaks at approximately 280 nm and 320 nm indicating phenolic concentrations. Studies analysing characteristics of dessert apple varieties with relevance for cider production will allow for informed decision making for both apple producers and cider makers.

A particular challenge to making wine from Pinot noir grapes is the delicate flavor, light color and poor ageing potential of the wine. Conventional Pinot noir must preparations were compared with those made using a skin-based supplement to assess the impact on non-bleachable (sulfur resistant) pigments in the wine. When supplemented with either fresh grape pomace of Pinot noir, Pinot gris or Chardonnay grapes; Pinot noir grape marc or a commercial liquid grape skin extract, the additional seeds and pulp from the supplements were shown to compromise the development of stable pigments in the wine. To compare the relative merits of tannin derived from grape skins and seeds, the supplements used in a parallel experiment were the skins alone of the same three grape varieties and at six months bottle age, the stable pigment concentration was found to exceed the amount attributable to the supplement. A third experiment used fermented grape skins as the supplement, with 85% of the supplementary anthocyanin recovered as stable pigment complexes in the wine. Notably, this series of experiments showed that supplements containing grape seeds appeared to compromise non-bleachable pigment formation in the wine while skin only supplements stimulated their development.

Ultraviolet and visible (UV–Visible) spectroscopy in conjunction with chemometrics modelling, was successfully applied to objectively differentiate grape juice press fractions (Vitis vinifera, cultivar Pinot Noir) for sparkling wine production. Two measurements modes were applied: (i) reflectance using a fiber optic probe in-line and (ii) transmission using a benchtop spectrophotometer. Different wavelength ranges for UV–Visible spectroscopy were evaluated and their ability to measure total phenolic concentrations in grape juice press fractions was compared. The differentiation of free run, early and late press fractions shows promise as a tool for the rapid discrimination of juice fractions when grapes for sparkling wine are pressed. Calibrations for total phenolics were prepared from press fraction spectral data using partial least squares (PLS) regression with a large number of wavelengths (230–700 nm) and multiple linear regression (MLR) using a small number of key wavelengths (230, 240, 280, 290, 520 nm). Calibration performance for both reflectance and transmission spectra was similar, but the best performing calibration used reflectance spectra at 240 and 290 nm (R2val = 0.95; SECV = 0.023 g/L; CV = 4.2%). Reflectance spectroscopy can thus be used in-line to predict total phenolics in grape juice with an acceptable accuracy and to discriminate press fractions. Insights arising from this research suggest a future possibility of objective, real-time discrimination of grape juice for better process control, monitoring and optimization of winemaking practices.

The aim of this preliminary study was to identify potential colour components, volatile and sensory attributes that could discriminate Pinot noir wines from five Australian winegrowing regions (Adelaide Hills, Yarra Valley, Mornington Peninsula, Northern and Southern Tasmania). The sensory analysis consisted of the Pivot&copy, Profile method that was performed by wine professionals. A headspace solid-phase microextraction-gas chromatography-mass spectrometry method was used to quantify multiple volatile compounds, while the Modified Somers method was used for colour characterisation. Analysis of data suggested ethyl decanoate, ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, in addition to decanoic acid as important contributors to the discrimination between regions. Similarly, wine hue, chemical age indices, total anthocyanin, and (%) non-bleachable pigment also discriminated wines between regions. The sensory analysis showed that wines from Mornington Peninsula were associated with the &lsquo, red fruits&rsquo, aroma, &lsquo, acidic&rsquo, and &lsquo, astringency&rsquo, palate descriptors, while those from Adelaide Hills were associated with the &lsquo, brown&rsquo, colour attribute. This study indicates regionality is a strong driver of aroma typicity of wine.

The feasibility of an ultraviolet-visible (UV-Vis) spectral phenolic fingerprint (SPF), combined with principal component analysis (PCA), is evaluated as a rapid, simple, and reliable technique for the discrimination of grape juice press fractions destined for the production of sparkling white wines. Juice press fractions of Vitis vinifera L. Chardonnay and Pinot noir grapes comprising free-run (i.e., juice released during the loading of press), cuvée (i.e., first press fraction), and taille (i.e., subsequent press fraction), were analyzed by SPF combined with multivariate data analysis. Two trials were carried out, a laboratory and a commercial scale trial. In both trials, cuvée and taille of Chardonnay and Pinot noir grapes were clearly separated in their corresponding PCA plots based on their SPF. The proposed method enables a rapid and objective discrimination of juice press fractions, which can be obtained using relatively inexpensive UV-Vis spectrophotometric equipment. Insights arising from this research suggest a future possibility of objective, real-time discrimination of juice quality that could liberate the winemaker from tasting juice at the press.

The phenolic composition, aroma, and sensory profiles were evaluated for Pinot noir wines made using four different maceration techniques that modified the floating pomace cap during fermentation: 1) daily plunging; 2) reduced skin particle size (accentuated cut edges, ACE); 3) submerged cap; and 4) ACE plus submerged cap. Throughout vinification, wines were analyzed using rapid analytical techniques to assess the following phenolic attributes: anthocyanin, tannin, nonbleachable pigments, color density, and hue. At six months bottle age (230 days postinoculation), sensory and aroma analyses were conducted on the finished wines. ACE macerated wines were found to have the highest proportion of red color, tannin, nonbleachable pigments, fruit and floral aromas, bitterness, and astringency. Submerging the pomace cap resulted in a lower concentration of phenolic components when compared to ACE wines, but resulted in a significantly higher phenolic content and dark cherry aromas and flavor when compared to the control wine. These findings suggest that the employment of either maceration technique has the potential to make a considerable difference to the wine style produced from a given parcel of fruit and may provide an opportunity to press wines earlier in the fermentation. Linear regression analyses were conducted to compare descriptive wine parameters with instrumental phenolic measurements and demonstrated several strong correlations: red color appearance was correlated with both color density (r2 = 0.95) and nonbleachable pigment (r2 = 0.95); dark fruit flavor was correlated with both color density (r2 = 0.85) and nonbleachable pigment (r2 = 0.85); and astringency was correlated with both tannin (r2 = 0.97) and nonbleachable pigment (r2 = 0.87), demonstrating that techniques of rapid chemical analysis were able to provide valuable insights into the sensory properties of the wine and may become useful tools for monitoring the development of the wine during vinification. While submerged cap vinification also increased the tannin and nonbleachable pigment profiles of the wine, ACE maceration was found to be significantly more effective and is likely to be more readily adapted for application in commercial wineries.

Modifying phenolic composition can improve the quality of Pinot noir wines and overcome common challenges associated with deficiencies in color, tannin, and aging potential. During fermentation, extraction of desirable components from the skin takes place primarily through the inner skin surface of the berry and from broken skin edges. Ostensibly, the extraction of phenolic compounds located in the skin may be enhanced by reducing the skin particle size. Theoretical analysis indicated that moderate fragmentation substantially decreased the surface area to perimeter ratio of grape skins. Three experiments showed that cutting grape skins into smaller fragments facilitated egress of color and tannin from the skin into the wine matrix. In each case, the treatment in which grapes were cut was compared with a crushed berry control made using conventional methods. Homogenization of berry tissues increased tannin concentration by 6-fold, stable pigment concentration by 45%, wine color density by 25%, and blue-purple coloration by 20% in wines at six months bottle age. Undifferentiated cutting of grapes increased tannin by 6.5-fold, stable pigment concentration by 70%, wine color density by 60%, and blue-purple coloration by 10%. A cutting technique that reduced grape skins to 6% of their original size without damaging the seeds produced wines that had 3-fold higher tannin concentration, 95% higher stable pigment concentration, 50% greater wine color density, and 20% increase in blue-purple coloration. The effects of reducing skin particle size on phenolic extraction were found to be much greater than those achieved using pectolytic enzymes. This innovative skin fragmentation technique has the potential to increase skin-derived red wine phenolics and is a viable alternative to maceration techniques currently used during winemaking.

Berry tissue components (skin, seed, and pulp) were isolated from Pinot noir grapes to determine the tannin content of each component. In addition, the role of each berry component in determining the phenolic profile of the wine was investigated by omitting or doubling each berry tissue in the must and fermenting these using submerged cap micro-vinification. Monomeric anthocyanin, total tannin and non-bleachable pigment concentrations in juice and wine were examined at seven time intervals from yeast inoculation (day 0) to 12 months bottle age (day 400). When included in the must, berry pulp was associated with reduced wine tannin concentration, an effect that was more selective for seed tannin. Consequently the tannin composition of wines made with whole-berry ferments most closely reflected that of skin tannin. The formation of non-bleachable pigments was greater in treatments where seeds were present during fermentation. However, when the contribution of seed tannin in wine was increased by doubling the complement of seeds in the must, anthocyanin concentration remained constant and non-bleachable pigments did not increase during ageing. Treatments with a double complement of grape skins were found to enhance both non-bleachable pigment and tannin in aged wines.

As a fast and easy-to-operate technique, infrared (IR) spectroscopy has gained wide industrial acceptance for routine wine analysis. Considering the continuing improvements in hardware and software design and the analytical requirements of real-time or multiparametric analysis by the modern grape and wine industry, it is anticipated that in the near future IR spectroscopy will progressively become a routine method for process monitoring and process control in different stages of grape and wine production. This review highlights recent developments and applications of IR spectroscopy (near- and mid-infrared) to measure compositional parameters in wine grapes, grape juice, and grapevine tissues (e.g., leaves, stems, grapevine wood). In addition, some critical aspects and limitations in instrument availability, type of application, and overall understanding of the technology, which can be barriers for adoption of IR technologies by the grape and wine industry, will be discussed.

Background and Aims: Quantification of botrytis bunch rot (BBR) in wine grapes, caused by Botrytis cinerea , is commonly done by visual estimation of the proportion of the area of individual bunches affected by BBR. Visual estimation was compared with four other quantification methods: digital image analysis, near-infrared and mid-infrared spectroscopy, and quantitative real-time polymerase chain reaction. Methods and Results: Visual estimation was found to vary significantly ( P P Conclusions: Near-infrared and mid-infrared spectroscopy require further calibration to quantify accurately BBR of low severity. Quantitative real-time polymerase chain reaction was the most accurate method but is unsuitable for routine use in the vineyard. RotBot was the most suitable and practical alternative to visual estimation, requiring no specialised equipment. Significance of the Study: Visual estimation was demonstrated to be prone to assessor bias. RotBot software is a suitable alternative that can be implemented immediately for objective quantification of BBR severity in white wine grapes. RotBot could be developed further and deployed in mobile devices for rapid sensing in the vineyard and easy collection of disease assessment data by wineries.

The current understanding of the influences of climate and viticultural practices on fruit quality at harvest and on sparkling wine quality is reviewed. Factors such as variety, clone, planting density, pruning method, local climate and soils, and current and future climate warming are discussed in the context of achieving a desired harvest quality. A common observation was the relatively less intensive viticultural management applied to grapes destined for sparkling wines compared to table wines throughout the world. Few studies have focused on management of fruit specifically for sparkling wine production. Given that it is accepted that a lower pH, higher titratable acidity, and lower soluble sugars than table wine are considered desirable for sparkling wine production, the literature from viticultural studies for table wines which influence these desired fruit quality parameters has been reported. Specific findings on canopy management, leaf removal, and yield manipulation for the production of table wines indicate potential for application and development to optimize fruit for the production of sparkling wines. Fruit quality targets are remarkably uniform across international growing regions but distinct combinations of variety, clone, and management are currently used to arrive at those targets. Further, studies of viticultural management, particularly those that alter cluster temperature and exposure to incident light, yield manipulation, and fruit quality are likely to best inform production techniques that result in fruit quality ideal for the production of premium sparkling wines. New challenges include the need for increasing mechanization to maintain cost-effective production and climate warming, which affects the production of fruit for premium sparkling production in terms of flavor development and high acidity. Current trends include the diversification of growing regions to cooler regions that enable the production of high acid fruit and increased exploration of alternative varieties and clones that are better suited to a warmer climate.

The relationship between grapevine vigour and grape and wine composition was investigated in this study. Own-rooted Pinot Noir grapevines were grown in a commercial vineyard in Tasmania, Australia, with uniform vineyard management practices. Vine vigours were determined by plant cell density (PCD) obtained from aerial photography. As vine vigour decreased, total soluble solid in grapes, total phenolics and anthocyanins in wines increased, while titratable acidity and yield decreased. Wines from the ultra low vine vigour zone had the highest concentrations of esters and alcohols. Higher level of linalool, nerol, geraniol, vitispirane, and β-ionone were observed in ultra low vigour and low vigour zones, but there was no obvious trend for citronellol and β-damascenone. Principal component analysis and discriminant analysis of the volatiles illustrated the differences among wines from the four vine vigour zones.

This study evaluated an in-field near-infrared (NIR) instrument to predict the contents of total nitrogen (TN), organic carbon (OC), potassium (K), sulfur (S), phosphorus (P), pH, and electric conductivity (EC) in soil vineyard samples (n = 70) sourced from three wine regions of Australia. Samples were analyzed using a portable NIR spectrophotometer (ASD FieldSpec III, 350-1800 nm). Partial least squares (PLS) regressions yield a coefficient of determination in calibration (R2) and a standard error in cross validation (SECV) of 0.74 (0.03) for TN, 0.92 (2.19) for S, 0.81 (0.42) for OC, 0.70 (109.2) for K, 0.84 (0.03) for EC, 0.83 (0.44) for pH, and 0.69 (24.6) for P, respectively. This study showed that it is possible to measure soil chemical properties in the vineyard, and the main advantages of this approach will be the speed, low cost, and ability to better manage and monitor soil fertility.

Pinot noir grapes have a unique phenolic profile which can impinge on the extraction and stabilisation of compounds such as anthocyanins and tannins which contribute to the colour and mouthfeel of red wine. This study examined the concentration of phenolic compounds in Pinot noir grape must and wine following application of a novel microwave maceration treatment for red grape must. Microwave maceration was shown to be highly effective for extraction of phenolics from grape solids into grape juice. When juices were fermented to wine, ultraviolet–visible spectrophotometry showed microwave maceration was associated with significantly higher concentrations of total phenolics, anthocyanin, tannin and pigmented tannin in wine at 18 months bottle age, compared with control wine. Mean tannin concentration in microwave treatment wine was 0.60 gm/L at 18 months, compared with 0.14 gm/L in control wine. The microwave treatment was also associated with a substantial and rapid decrease in the grape-associated yeast population, compared with control maceration, and a shorter lag phase at the outset of alcoholic fermentation. Based on this study, microwave maceration warrants further investigation as a potential industrial-scale application in red winemaking.

Botrytis bunch rot (BBR), one of the most important diseases of wine grapes, is usually quantified in the vineyard by visual estimation of percentage disease severity on individual grape bunches. This method is prone to assessor error and there is a need for a more objective quantification method that is cost-effective and practical. Near infrared (NIR; 800–2690 nm) and mid-infrared (mid-IR; 2510–25, 770 nm) spectroscopy were investigated as alternatives to visual estimation. Partial least squares (PLS) analysis of the NIR and mid-IR spectra from near-ripe grape bunches from Tasmanian vineyards was used to generate prediction models from both raw data and data pre-processed using the Savitzky–Golay derivative. The entire spectral range for each spectral region was analysed first, after which specific spectral ranges were analysed based on their influence on the initial PLS analysis. The spectral range of 1260–1370 nm with Savitzky–Golay smoothing and first derivative pre-processing produced the PLS model with the highest predictive ability in the NIR spectral region, with a ratio of standard error of prediction to standard deviation ( RPD) of 2.2. The spectral range of 8760–9520 nm with Savitzky–Golay smoothing and first derivative pre-processing produced the PLS model with the highest predictive ability in the mid-IR spectral region, with a RPD of 1.7. Both methods demonstrated the potential for spectroscopic quantification of BBR. However, further calibration is required to increase the accuracy of these models, particularly at low BBR severities, if they are to be considered suitable for use in the vineyard.

Information relating to tannin concentration in grapes and wine is not currently available simply and rapidly enough to inform decision-making by grape growers, winemakers, and wine researchers. Spectroscopy and chemometrics have been implemented for the analysis of critical grape and wine parameters and offer a possible solution for rapid tannin analysis. We report here the development and validation of an ultraviolet (UV) spectral calibration for the prediction of tannin concentration in red wines. Such spectral calibrations reduce the time and resource requirements involved in measuring tannins. A diverse calibration set ( n = 204) was prepared with samples of Australian wines of five varieties (Cabernet Sauvignon, Shiraz, Merlot, Pinot Noir, and Durif), from regions spanning the wine grape growing areas of Australia, with varying climate and soils, and with vintages ranging from 1991 to 2007. The relationship between tannin measured by the methyl cellulose precipitation (MCP) reference method at 280 nm and tannin predicted with a multiple linear regression (MLR) calibration, using ultraviolet (UV) absorbance at 250, 270, 280, 290, and 315 nm, was strong ( r 2 val=0.92; SECV=0.20 g/L). An independent validation set ( n = 85) was predicted using the MLR algorithm developed with the calibration set and gave confidence in the ability to predict new samples, independent of the samples used to prepare the calibration ( r 2 val = 0.94; SEP = 0.18 g/L). The MLR algorithm could also predict tannin in fermenting wines ( r 2 val=0.76; SEP=0.18 g/L), but worked best from the second day of ferment on. This study also explored instrument-to-instrument transfer of a spectral calibration for MCP tannin. After slope and bias adjustments of the calibration, efficient calibration transfer to other laboratories was clearly demonstrated, with all instruments in the study effectively giving identical results on a transfer set.

This study reports the effect of microwaving on the chemical composition [pH, total soluble solids (TSS), dry matter (DM) and total anthocyanins extraction], and the visible (VIS) and (NIR) spectra of red grape homogenates. It was observed that microwaving red grape homogenates prior to analysis improved the NIR calibrations for total anthocyanins (SECV: 0.21–0.13 mg g−1) and TSS (SECV: 0.89–0.54 °Brix), however no improvements in the NIR calibrations for DM were observed. Microwaving red grape samples prior to NIR scanning also caused an increased in absorbance for samples heated for up to 3 min, particularly in those wavelengths associated with water (1400 nm and 1930 nm). The practical implication of this study is that microwaving of red grape samples prior to scanning did not improve the NIR calibration statistics for the most common chemical parameters measured in red grapes.

The objective of this study was to comprehensively and methodically evaluate the small-scale mash parameters of the standard Congress (EBC and ASBC) mash protocol in order to modernize this protocol so it better emulates modern commercial brewing practices. For the recommended final 65°C mash protocol, the key parameters were grist milling at 0.7 mm by disc mill, an initial grist/water ratio of 1:3, an initial mash temperature of 65°C, and an initial mashing phase of 65°C for 60 min. Of lesser importance, but still adopted due to widespread use in commercial brewing, was the addition of CaSO 4 (0.3 mM) and completion of mashing at 74°C, after which the grist/water ratio was decreased to 1:6 before cooling and lautering. The "final 65°C" mash protocol was compared with the Congress mash protocol and a simple 65°C variant ("old 65°C") mash protocol to determine the influence of mash protocol on extract and fermentability using a selection of 29 commercial malts. It was demonstrated that the choice of mash protocol applied had subtle, but important, impacts on the determination of extract and prediction of fermentability. Through a relatively simple modification of the small-scale wort production protocol, measurement of malt lautering performance, based on the volume of wort lautered at 25 min, was also proposed. The investigation showed that the mash protocol used could interact with subtle differences in malt characteristics, which could alter the relative importance of the predictive parameters of important malt quality characteristics such as extract, fermentability, and lautering. Researchers and malt quality technicians should be aware that these subtle influences could potentially result in unexpected biases in routine malt analyses and research investigations of components that influence malting and brewing parameters.

Background and Aims: Near infrared (NIR) spectroscopy techniques are not only used for a variety of physical and chemical analyses in the food industry, but also in remote sensing studies as tools to predict plant water status. In this study, NIR spectroscopy was evaluated as a method to estimate water potential of grapevines. Methods and Results: Cabernet Sauvignon, Chardonnay and Shiraz leaves were scanned using an Integrated Spectronic (300–1100 nm) or an ASD FieldSpec® 3 (Analytical Spectral Devices, Boulder, Colorado, USA) (350– 1850 nm) spectrophotometer and then measured to obtain midday leaf water potential using a pressure chamber. On the same shoot, the leaf adjacent the one used for midday leaf water potential measurement was used to measure midday stem water potential. Calibrations were built and NIR showed good prediction ability (standard error in cross validation (SECV)

Information about changes in grape berry composition (e.g. total anthocyanins, total soluble solids and pH) in the context of the main growing parameters said to be changing with climate change (e.g. temperature, rainfall) is limited. This information is necessary in order to predict wine composition in possible future climate change scenarios as well as to help us to understand the adaptability of new varieties, new viticultural regions or winemaking practices. The aims of this study were to look at grape berry composition results of ten successive vintages in the context of temperature, rainfall and CO2 emissions. Results of this study confirmed observations and anecdotal evidence that warm viticultural regions tend to produce grapes with lower total anthocyanins (in average 0.9 mg g−1) compared with cool regions. However, some growing regions and seasons may have sub-optimal temperatures for anthocyanin production and may improve with climate change related temperature rises. Although the results presented here are from observations, we believe that these data can be utilised and incorporated to climate change modelling systems, in order to better understand and define the effect of climate change on the environmental and economical sustainability of the wine production in Australia.

Measuring chemical composition is a common approach to support decisions about allocating foods and beverages to grades related to market value. Red wine is a particularly complex beverage, and multiple compositional attributes are needed to account for its sensory properties, including measurement of key phenolic components such as anthocyanins, total phenolics, and tannin, which are related to color and astringency. Color has been shown to relate positively to red wine grade; however, little research has been presented that explores the relationship between astringency-related components such as total phenolic or tannin concentration and wine grade. The aim of this research has been to investigate the relationship between the wine grade allocations of commercial wineries and total phenolic and tannin concentrations, respectively, in Australian Shiraz and Cabernet Sauvignon wines. Total phenolic and tannin concentrations were determined using the methyl cellulose precipitable (MCP) tannin assay and then compared to wine grade allocations made by winemaker panels during the companies' postvintage allocation process. Data were collected from wines produced by one Australian wine company over the 2005, 2006, and 2007 vintages and by a further two companies in 2007 (total wines = 1643). Statistical analysis revealed a positive trend toward higher wine grade allocation and wines that had higher concentrations of both total phenolics and tannin, respectively. This research demonstrates that for these companies, in general, Cabernet Sauvignon and Shiraz wines allocated to higher market value grades have higher total phenolics and higher tannin concentrations and suggests that these compositional parameters should be considered in the development of future multiparameter decision support systems for relevant commercial red wine grading processes. In addition, both tannin and total phenolics would ideally be included because although, in general, a positive relationship exists between the two parameters, this relationship does not hold for all wine styles.

This study demonstrates the application of two-dimensional correlation analysis to evaluate the effect of different temperatures on the headspace of wines analysed using a mass spectrometry electronic nose instrument in order to obtain their fingerprint. We have demonstrated that for a complex sample matrix such as wine, selection of an optimum sampling temperature of the headspace will be critical. Additionally, it was observed that small changes in headspace temperature can have a significant effect on the classification or fingerprint of wines analysed. Overall, the fingerprint of the red wine volatiles collected from the headspace seems to be less affected by temperature, while white wines are more affected by changes in volatile compounds present in the wine matrix. It was highlighted that both wine types had different behaviour in response to temperature changes in the headspace. The practical implication of this study is that care in the selection of the optimal temperature should be exercised when obtaining the MS fingerprint of wines using headspace.

Rapid methods employing instruments such as electronic noses (EN) or gas sensors are used in the food and beverage industries to monitor and assess the composition and quality of products. Similar to other food industries, the wine industry has a clear need for simple, rapid and cost effective techniques for objectively evaluating the quality of grapes, wine and spirits. In this study a mass spectrometry based electronic nose (MS-EN) instrument combined with chemometrics was used to predict the geographical origin of Tempranillo wines produced in Australia and Spain. The MS-EN data generated were analyzed using principal components analysis (PCA), partial least squares discriminant analysis (PLS-DA) and stepwise linear discriminant analysis (SLDA) with full cross validation (leave-one-out method). The SLDA classified correctly 86% of the samples while PLS-DA 85% of Tempranillo wines according to their geographical origin. The relative benefits of using MS-EN will provide capability for rapid screening of wines. However, this technique does not provide the identification and quantitative determination of individual compounds responsible for the different aroma notes in the wine.

Prediction of malt fermentability (apparent attenuation limit — AAL) by measurement of the diastatic power enzymes (DPE), α-amylase, total limit dextrinase, total β-amylase, β-amylase thermostability, and the Kolbach index (KI or free amino nitrogen — FAN) is superior to the conventional use of diastatic power (DP) alone. The thermostability of β-amylase is known to be an important factor in determining fermentability, thus the thermostability of the other relatively thermolabile enzyme, limit dextrinase, was investigated to determine if it was also useful in predicting fermentability. To facilitate this aim, methods were developed for a rapid and cost efficient assay of both β-amylase and limit dextrinase thermostability. Internationally important Australian and international malting varieties were compared for their total limit dextrinase and β-amylase activity and thermostability. Interestingly, the level of limit dextrinase thermostability was observed to be inversely correlated with total limit dextrinase activity. The prediction of malt fermentability was achieved by both forward step-wise multi-linear regression (MLR) and the partial least squares (PLS) multivariate model development methods. Both methods produced similar identifications of the parameters predicting wort fermentability at similar levels of predictive power. Both models were substantially better at predicting fermentability than the traditional use of DP on its own. The emphasis of this study was on the identification of predictive factors that can be consistently used in models to predict fermentability, because the model parameter estimates will subtly vary depending on mashing conditions, yeast strain/fermentation conditions and malt source. The application of these multivariate model development methods (PLS and MLR) enabled the identification of further potential fermentability predicting factors. The analyses divided the predictive parameters into those defined by DP enzymes and those associated with modification (KI, FAN, fine/coarse difference, wort β-glucan and friability). Surprisingly, limit dextrinase thermostability was not a substantial predictor of fermentability, presumably due to its negative correlation with total limit dextrinase activity. The application of these insights in the malting and brewing industries is expected to result in substantial improvements in brewing consistency and enable more specific quality targets for barley breeder's progeny selection cut-off limits to be more precisely defined.

The combination of mid infrared (MIR) spectroscopy and multivariate analysis was explored as a tool to classify commercial wines sourced from organic (ORG) and non-organic (NORG) production systems. Commercial ORG (n = 57) and NORG (n = 115) red and white wine samples from 13 growing regions in Australia were analysed using a MIR spectrophotometer. Discriminant models based on MIR spectra were developed using principal component analysis (PCA), discriminant partial least squares (DPLS) regression and linear discriminant analysis (LDA). Overall, the LDA models based on the PCA scores correctly classified on average, more than 75% of the wine samples while the DPLS models correctly classified more than 85% of the wines belonging to ORG and NORG production systems, respectively. These results showed that MIR combined with discriminant techniques might be a suitable method that can be easily implemented by the wine industry to classify wines produced under organic systems.

The effect of sample freezing, speed of homogenisation, time of homogenisation and homogeniser type on the chemical composition and near infrared (NIR) spectra of white grape berry samples has been examined. Samples of Chardonnay and Riesling sourced from South Australia were homogenised fresh and after different period of frozen storage (overnight, or 1, 2, 3 and 10 weeks) using a Retsch homogeniser or Waring blender. Two speeds (high and low) and two time intervals (20 and 60 s) were applied for samples homogenised with the Waring blender. All samples were analysed immediately after homogenisation by chemical and NIR analysis. The results showed that neither short time freezing nor prolonged frozen storage had any influence on TSS concentration and pH. However a significant increase in concentration of total phenolics was observed in samples after freezing and frozen storage. With the Waring blender, speed and time influenced total phenolics measurement. There was also an effect observed on the NIR spectra of the samples due to different speed and time of homogenisation.

Samples (n = 620) of homogenized red grape berries were analyzed using a visible and near-infrared (NIR) spectrophotometer (400-2500 nm) in reflectance. The spectra and the analytical data were used to develop partial least-squares calibrations to predict dry matter (DM) content and condensed tannins (CT) concentrations. The coefficient of determination in cross-validation and the standard error of cross-validation were 0.92 and 0.83% w/w for DM and 0.86 and 0.46 mg/g epicatechin equivalents for CT, respectively. The standard error in prediction was 1.34% w/w for DM and 0.89 mg/g epicatechin equivalents for CT, respectively. By implementing a NIR spectroscopy method to measure DM and CT in red grape homogenates, we have developed an approach that is suited to large-scale compositional analysis in commercial wine production facilities, as it enables the analysis of large numbers of samples needed to stream batches of fruit. From an economical point of view, the calibration models could be achieved with relatively small data sets. Thus, NIR offers a suitable and efficient tool for the simultaneous measurement of DM and CT in addition to other important parameters in red grape homogenates such as total anthocyanins, total soluble solids, and pH, with minimal sample preparation and low cost.

Sensory analysis of wine involves the measurement, interpretation and understanding of human responses to the properties perceived by the senses such as sight, smell and taste. The sensory evaluation of wine is often carried out by wine judges, winemakers and technical staff, and allows characterization of the quality of the wine. However, this method is lengthy, expensive, and its results depend on panel training and the specific vocabulary used by the panel. A robust, rapid, unbiased and inexpensive method to assist in quality assessment purposes will therefore be beneficial for the modern wine industry. This study aims to investigate the relationship between sensory analysis, visible (VIS) and near-infrared (NIR) spectroscopy to assess sensory properties of commercial Australian wine varieties. For the purposes of this study 118 red wine samples (Cabernet Sauvignon, Shiraz, Pinot Noir, Tempranillo, Nebbiolo and blends) graded by a panel of experienced tasters and scored according to the Australian wine show system were scanned in transmission in the VIS and NIR range (400-2,500 nm). Partial least squares regression models were developed between the overall score given by the judges and the combined VIS-NIR spectra, using full cross validation (leave-one-out method). The results showed that NIR spectroscopy was able to predict wine quality scores in red wine samples (R = 0.61 and standard error of prediction of 0.81). The practical implication of this study is that instrumental methods such as VIS-NIR spectroscopy can be used to complement sensory analysis and can facilitate the task at early stages of product development, making high-throughput screening of novel products feasible or maintaining the consistency of the product.

The effect of sample processing with three different blenders, sample freezing and storage time on the determination of berry quality parameters - total anthocyanins, total soluble solids (TSS), total phenolics (TP) and pH - in homogenates of red grape berries has been examined. Samples of Cabernet Sauvignon, Merlot and Shiraz from four regions of South Australia were homogenised using Ultra-Turrax, Waring or Retsch commercial blenders applied to fresh samples, and to samples held in frozen storage overnight or for 1, 3, 6 and 12 months. All samples were analysed immediately after homogenisation. The results showed that neither homogeniser type nor freezing had any significant effect on total anthocyanins or TSS. However, freezing had an effect on total anthocyanins concentrations in samples with higher colour. The homogeniser type had a significant effect on TP and pH for all varieties analysed together. Freezing had no significant effect on TP, but significant effect on pH, the value being greater in samples at the lower end of the pH range. Frozen storage time of up to 3 months had no significant effect on total anthocyanins, TSS or TP. Statistically significant differences were observed in the concentration of total anthocyanins in samples after 3 months of frozen storage.

Volatile chemical compounds responsible for the aroma of wine are derived from a number of different biochemical and chemical pathways. These chemical compounds are formed during grape berry metabolism, crushing of the berries, fermentation processes (i.e. yeast and malolactic bacteria) and also from the ageing and storage of wine. Not surprisingly, there are a large number of chemical classes of compounds found in wine which are present at varying concentrations (ng L(-1) to mg L(-1)), exhibit differing potencies, and have a broad range of volatilities and boiling points. The aim of this work was to investigate the potential use of near infrared (NIR) spectroscopy combined with chemometrics as a rapid and low-cost technique to measure volatile compounds in Riesling wines. Samples of commercial Riesling wine were analyzed using an NIR instrument and volatile compounds by gas chromatography (GC) coupled with selected ion monitoring mass spectrometry. Correlation between the NIR and GC data were developed using partial least-squares (PLS) regression with full cross validation (leave one out). Coefficients of determination in cross validation (R(2)) and the standard error in cross validation (SECV) were 0.74 (SECV: 313.6 microg L(-1)) for esters, 0.90 (SECV: 20.9 microg L(-1)) for monoterpenes and 0.80 (SECV: 1658 microg L(-1)) for short-chain fatty acids. This study has shown that volatile chemical compounds present in wine can be measured by NIR spectroscopy. Further development with larger data sets will be required to test the predictive ability of the NIR calibration models developed.

Visible (VIS) and near infrared (NIR) spectroscopy combined with chemometrics was used in an attempt to classify commercial Riesling wines from different countries (Australia, New Zealand, France and Germany). Commercial Riesling wines (n = 50) were scanned in the VIS and NIR regions (400-2500 nm) in a monochromator instrument, in transmission mode. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and stepwise linear discriminant analysis (SLDA) based on PCA scores were used to classify Riesling wines according to their country of origin. Full cross validation (leave-one-out) was used as the validation method when classification models were developed. PLS-DA models correctly classified 97.5%, 80% and 70.5% of the Australian, New Zealand and European (France and Germany) Riesling wines, respectively. SLDA calibration models correctly classified 86%, 67%, 67% and 87.5% of the Australian, New Zealand, French and German Riesling wines, respectively. These results demonstrated that the VIS and NIR spectra contain information that when used with chemometrics allow discrimination between wines from different countries. To further validate the ability of VIS-NIR to classify white wine samples, a larger sample set will be required. Refereed/Peer-reviewed

The use of visible (Vis) and near infrared (NIR) spectroscopy was explored as a rapid, simple and low cost measurement of the concentration of total glycosylated compounds in white grape juice. The effects of variety (Chardonnay, Riesling and Sauvignon Blanc), winery and vintage (2004 to 2006) on the Vis-NIR spectra were also examined. Juice samples from South Australian wineries were scanned in transmittance mode on a FOSS NIRSystems6500 instrument and subjected to laboratory analyses for the measurement of the concentration of total glycosylated compounds (G-G), total soluble solids (TSS), pH and total phenolics (TP). Partial least squares (PLS) regression method was used to relate the G-G reference data to the Vis-NIR spectra. For all samples, PLS regression resulted in a coefficient of determination in calibration (R )and standard error of cross validation (SECV) of 0.82 and 49.15 μM, respectively. Splitting the sample set by variety, winery or vintage improved the PLS calibrations for the variety sets. The results show that Vis-NIR spectroscopy has potential for use as a rapid, semi-quantitative technique to predict G-G concentration in white grape juices as 'low', 'medium' or 'high'. This method will be valuable when taking decisions at the winery during vintage to allocate juices according to their aroma potential. Further studies are in progress to validate the robustness and accuracy of the calibration models.

The methyl cellulose precipitable (MCP) tannin assay and a modified version of the Somers and Evans color assay were adapted to high-throughput (HTP) analysis. To improve efficiency of the MCP tannin assay, a miniaturized 1 mL format and a HTP format using 96 well plates were developed. The Somers color assay was modified to allow the standardization of pH and ethanol concentrations of wine samples in a simple one-step dilution with a buffer solution, thus removing inconsistencies between wine matrices prior to analysis and allowing for its adaptation to a HTP format. Validation studies showed that all new formats were efficient, and results were reproducible and analogous to the original formats.

Many studies have reported the use of near infrared (NIR) spectroscopy to characterize wines or to predict wine chemical composition. However, little is known about the effect of variation in temperature on the NIR spectrum of wine and the subsequent effect on the performance of calibrations used to measure chemical composition. Several parameters influence the spectra of organic molecules in the NIR region, with temperature being one of the most important factors affecting the vibration intensity and frequency of molecular bonds. Wine is a complex mixture of chemical components (e.g. water, sugars, organic acids, and ethanol), and a simple ethanol and water model solution cannot be used to study the possible effects of temperature variations in the NIR spectrum of wine. Ten red and 10 white wines were scanned in triplicate at six different temperatures (25 degrees C, 30 degrees C, 35 degrees C, 40 degrees C, 45 degrees C and 50 degrees C) in the visible (vis) and NIR regions (400-2500 nm) in a monochromator instrument in transmission mode (1 mm path length). Principal component analysis (PCA) and partial least squares (PLS) regression models were developed using full cross validation (leave-one-out). These models were used to interpret the spectra and to develop calibrations for alcohol, sugars (glucose+fructose) and pH at different temperatures. The results showed that differences in the spectra around 970 nm and 1400 nm, related to O-H bonding were observed for both varieties. Additionally an effect of temperature on the vis region of red wine spectra was observed. The standard error of cross validation (SECV) achieved for the PLS calibration models tended to inverse as the temperature increased. The practical implication of this study it is recommended that the temperature of scanning for wine analysis using a 1 mm path length cuvette should be between 30 degrees C and 35 degrees C.

Spectroscopic techniques such as near infrared (NIR) spectroscopy are used in the food industry to monitor and assess the composition and quality of products. Similar to other food industries, the wine industry has a clear need for simple, rapid and cost-effective techniques for objectively evaluating the quality of grapes, wines and spirits. Thirty years have passed since the first work reported by Kaffka and Norris on the use of NIR spectroscopy to analyse wine. Since then, NIR spectroscopy has been used for grape and wine compositional analysis, fermentation monitoring and wine grading. However, the use of NIR spectroscopy in the wine industry is still in its infancy. From the analysis of the scatter information available, it appears that NIR spectroscopy is applied in different steps during the wine production. This review highlights the most recent applications of NIR spectroscopy in the grape and wine industry. Additional information is also provided on the use of mid infrared spectroscopy for wine analysis.

In a study of visible (vis) and near infrared (NIR) spectra collected from grape samples representing many growing vintages, varieties and regions, WinISI LOCAL performed better than modified partial least squares in the prediction of anthocyanin and pH. However, both algorithms performed equally well for the prediction of total soluble solids (TSS). Calibrations for anthocyanins and pH relied mainly on the visible wavelengths, but pH calibrations may result from pH effects on the spectral properties of anthocyanin. On the other hand, calibrations for TSS relied mainly on NIR wavelengths. An examination of the LOCAL match sets showed that, in addition to spectral matching, there appeared to be concomitant compositional matching, possibly due to dominant spectral features related to the relevant analyte. Observations imply that calibrations for anthocyanins, pH and TSS in grapes are not restrained by vintage, variety and region. A more important factor in determining a robust, global application may be to ensure that the full concentration range of the analyte is well represented in the calibration database.

A precipitation assay is presented that enables tannin measurement in matrices of red wine, 50% ethanol grape extract and aqueous tannin solutions. By exploiting the polysaccharide polymer methyl cellulose to precipitate tannins, the absorbance of phenolics at 280 nm before and after tannin precipitation (subtractive approach) can be obtained, thus enabling selective measurement of tannin only. This methyl cellulose precipitable (MCP) tannin assay allows complete precipitation of tannin from red wine and from grape homogenate extracts. The subtractive assay is both simple and robust, selective for condensed tannins and does not suffer interference from other 280 nm-absorbing phenolics such as anthocyanins or catechins. Matrix effects have only minimal impact on the assay performance and validation parameters indicate a robust performance. There was good correlation between tannin measured by reverse-phase HPLC and the MCP tannin assay for 121 Australian red wines (r = 0.74) and also 54 grape extracts (r = 0.79). We envisage that the technical simplicity of this tannin assay will enable widespread research and field applications. In addition, an alternative format that requires re-solubilisation of the tannin-polymer pellet in acetonitrile is reported, which is particularly suitable for measurement of smaller tannin concentrations. Notwithstanding that option, technical requirements of the re-solubilisation step lead us to suggest that the subtractive format would be simple for adoption by wine industry practitioners.