Sensory Characterisation of Australian Cabernet Sauvignon Wine Typicity
| dc.contributor.advisor | Jeffery, David | |
| dc.contributor.advisor | Bastian, Susan | |
| dc.contributor.advisor | Capone, Dimitra | |
| dc.contributor.author | Souza Gonzaga, Lira | |
| dc.contributor.school | School of Agriculture, Food and Wine | en |
| dc.date.issued | 2021 | |
| dc.description.abstract | Wine is a product with a complex composition that undergoes a diverse number of processes during its production that will eventually impact on the final chemical and sensory profiles. Those processes can and will change depending on the geographical area so that grape growing and winemaking practices can account for unique regional features, such as the biome associated with the vineyard, the logistical and technological inputs at the winery, and the social environment involved with wine commercialisation. Consequently, when a certain wine style is achieved, it will inevitably carry a connection with its provenance that can be expected to be expressed through sensory traits. Conveying unique features that are connected to the wine’s place of origin can be defined as wine typicity. Over the years, wine typicity has been increasingly established as a concept to consider in the market and can also be an important factor for the consumer’s purchase decision. However, wine typicity is still concept with a broad definition that has been tailored throughout the years to suit different research purposes. Considering provenance connection and the notion of unique expression, this thesis starts by reviewing the literature that covers the wine typicity concept and the influencing factors around it (Chapter 1). After reviewing the literature around wine typicity, a concept is proposed encompassing aspects that are considered for the purposes of this thesis: “Wine typicity can be defined as a juxtaposition of unique traits that define a class of wines having common aspects of terroir involving biophysical and human dimensions that make the wines recognisable, and in theory, unable to be replicated in another territory.”. The literature review also covers consumer perspectives regarding the concept of wine typicity and details previous studies that have reported the importance of typicity for consumer behaviour and purchase decisions. Similarly, to other nations, wine producing regions in Australia are divided into Geographical Indications (GIs) that relate wine to it geographical production area. Among all the red varieties produced in those GI, Cabernet Sauvignon is the second most important to the Australian industry, and is an internationally renowned variety. Thus, the different research studies reported in this thesis (Chapter 2 to 5) aimed to offer a better understanding of the sensory aspects involved with the typicity of Australian Cabernet Sauvignon wines from different GIs. Notably, different Cabernet Sauvignon producing regions of Australia are included throughout the studies in this thesis, namely Coonawarra, Margaret River, and Yarra Valley. Additionally, as the birthplace of the Cabernet Sauvignon variety, Bordeaux in France was also included for benchmark purposes. The first research publication (Chapter 2) used a web-scraping software and content analysis to investigate over 2,500 web-based Cabernet Sauvignon wine reviews from established Australian wine writers, including their tasting notes and overall scores. Sensory analysis was also conducted with a set of 84 Cabernet Sauvignon wines using 11 industry experts, who provided freely chosen descriptors. A sensory lexicon was created using the content analysis software and the frequencies for each term were statistically analysed. Correspondence analysis showed descriptors that were associated with the sensory profiles of the studied regions along with descriptors that were most commonly associated with assigned quality scores. When both data sets were compared, a higher agreement was shown for quality assessments than for regional profiles, whereby wine writers and expert panellists had a better alignment with descriptors that were associated with low and high quality wines. Using the same expert panel and the set of 84 Cabernet Sauvignon wine samples, the second research publication (Chapter 3) combined a variant of rate-all-that-apply and a sorting task data with a separate descriptive analysis conducted by a panel of 10 trained tasters using a subset (n = 52) of the initially-studied wines. The sorting task data demonstrated that the sample segregation undertaken by the expert panel was mainly based on sensory profiles rather than regionality, although there was a clearer segregation on the Bordeaux wine samples. Both panels (expert and trained panel), however, raised multiple sensory attributes associated with the regional profile of wines from the four wine regions specified earlier. Some of the attributes, such as ‘minty’, ‘cooked vegetables’ and ‘floral’, were in close agreement between the two sensory cohorts. Understanding what represents sensory regionality (regional typicity) for the Australian Cabernet Sauvignon wines is important, so procedures and environmental characteristics that influence regional typicity can be pinpointed. However, for the commercialisation of the product, comprehending the target market and how consumers behave is also an important tool for the industry. Therefore, the third research publication (Chapter 4) dealt with consumer perspectives around the wine typicity concept and the impact of provenance information when tasting wine. Red wine consumers (n = 112) were recruited to taste a restricted subset of samples (n = 8) drawn from the previous studies. The participants were divided into two groups: one group received origin information of the wine prior tasting and the other tasted the samples blindly. With the chosen experimental design, this study was able to demonstrate that provenance information had a positive impact on consumer hedonic scores even though both groups essentially perceived the sensory profiles of the wines in the same way. A survey conducted with these consumers about the wine typicity concept showed that many were familiar with the typicity term, and for a moderate number, typicity was deemed to be important for their purchase decision. The last manuscript (Chapter 5) aimed to verify if the sensory traits found in Chapters 2, 3, and 4 were important for Coonawarra typicity. Additionally, this manuscript explored the possible association between spectrofluorometric analysis, as a highly selective and sensitive methodology, and sensory traits of Coonawarra Cabernet Sauvignon wines. Thus, commercially-produced but unfinished Cabernet Sauvignon wines from different vineyards of the Coonawarra GI were evaluated through rate-all-that-apply (RATA) sensory testing (n = 60), along with basic chemistry, and spectrofluorometric analysis. The sample set was clustered into five distinctive sensory profiles through agglomerative hierarchical clustering (AHC) analysis that were modelled against fluorescence data with extreme gradient boosting discriminant analysis (XGBDA), a machine learning technique. This enabled classification of the wines according to their sensory clustering with 100% accuracy using excitation and emission matrices (EEMs) from spectrofluorometric analysis. Four main fluorophores characterising the sample set were tentatively identified through parallel factor analysis (PARAFAC) and associated with classes of phenolic compounds commonly present in red wine. Even though it is likely to be an indirect association, the EEMs of those four fluorophores were tentatively associated with the sensory descriptors found through the RATA assessment. The sensory panel ratings for perceived astringency mouthfeel were also predicted (68.1% of confidence) through a partial least squares regression model that explained 84.8% of the variance in the results. Considering the optimistic nature of the task described in this manuscript promising results was found, showing that fluorescence analysis might be the key to predict sensory traits from a small number of wine compositional factors. | en |
| dc.description.dissertation | Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2021 | en |
| dc.identifier.uri | https://hdl.handle.net/2440/134171 | |
| dc.language.iso | en | en |
| dc.provenance | This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals | en |
| dc.subject | Regionality | en |
| dc.subject | typicality | en |
| dc.subject | provenance | en |
| dc.subject | consumer behaviour | en |
| dc.subject | rate-all-that-apply | en |
| dc.subject | content analysis | en |
| dc.subject | sorting task | en |
| dc.subject | expert panel | en |
| dc.subject | descriptive analysis | en |
| dc.title | Sensory Characterisation of Australian Cabernet Sauvignon Wine Typicity | en |
| dc.type | Thesis | en |
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