Tracking trends in Australian wine composition and vineyard and winery practices
This project will track trends in Australian wine composition and vineyard and winery practices. Compositional trends will principally be monitored by collating analytical data from wines submitted to the AWRI’s analytical laboratories for commercial analysis; thereby extracting substantial value from an existing sample set consisting of more than 25,000 samples analysed annually, at a cost of considerably more than a million dollars. If necessary, that existing data set will be augmented with supplementary samples and analyses to address identified gaps (for example, in relation to specific regions, wine types or analytes), or through the addition of other data sets (such as Wine Australia’s export certificate data).
Trends in production practices will principally be monitored via a web-based survey of vineyard and winery practices performed at approximately five-yearly intervals, supplemented by visits to a range of producers and industry bodies, to consult and gain additional perspectives on the compiled data. These surveys will be equivalent to the AWRI Vineyard and Winery Practices Survey performed in 2016, which is to be published in 2018.
AWRI Vineyard & Winery Practices Survey
The full report from a major survey of Australian vineyard and winery practices was released during the year and is available for download (Figure 30). The report presents information on the fundamentals of grape and wine production in Australia as well as on the adoption of new technologies across different operational sizes and vineyard regions. It illustrates that some technologies have been widely adopted (e.g. cross flow filtration for wine clarification), while others so far have not been (e.g. sensors to monitor ferment progress).
SO2 in wine
As part of its ongoing work to track the compositional trends in Australian wine, the AWRI worked with Wine Australia and data from its export database to review the SO2 level in more than 3,000 wines from the 2016 and 2017 vintages. The data from this unique source was able to shed significant light on recent trends in the use of this important preservative in different wines. The first, and perhaps most surprising result, was that there was not a significant difference in free sulfur dioxide concentrations between red and white wines, with means of 30.5 and 31.0 mg/L and standard deviations of 9.5 and 10.4 mg/L respectively. This is despite there being significant differences in the average pH for red and white wines, which can have a significant impact on the effectiveness of SO2 as an inhibitor of microbiological activity. The results may reflect a greater concern about managing oxidation in packaged wine rather than consideration of microbial issues. The distribution of free SO2 concentrations for red and white wines is shown in Figure 31.
Of the sample set analysed, 95% were declared as having free SO2 levels between 20 and 40 mg/L. There was very little variation between the two vintages in the study or among the major grape varieties. Only Pinot Noir and Grenache wines were shown to have significantly lower mean concentrations of free SO2 (23.7 and 27.3 mg/L respectively). With Pinot Noir this may reflect efforts to avoid colour loss in this variety.
Unsurprisingly, for total SO2 the mean results were higher for white wines than for reds (113.9 and 83.8 mg/L respectively) reflecting differences in red and white wine production. Levels of total SO2 are regulated in Australia and most export markets and as such monitoring of the results can be important. All the wines in the study were compliant with the Australian limit of 250 mg/L, with the vast majority of wines significantly below this level (99% of red wines <160 mg/L and 99% of white wines <190 mg/L), easily meeting the requirements of Australia’s major export markets. The differences between vintages were small and statistically insignificant (Figure 32). Comparison with the median values for earlier vintages previously published by the AWRI shows a continued downward trend in total SO2 for white wines. For red wines there appears to be an increase in values; however, it was not clear if this was significant or an artefact of the previous study which relied on results from wines which had been bottled for an unknown period of time. This data will be reviewed on an annual basis.