The Australian Wine Research Institute’s Analytical Service - Analyses

Sensory evaluation

• Wine taint and fault vials

The Analytical Service has access to a number of trained and experienced assessors employed within the AWRI. These assessors are asked to perform sensory evaluation of wines submitted by industry or in the course of research projects, with various panels available qualified for different test types. A range of sensory evaluation tests can be conducted upon client request including wine quality evaluation, taint assessment, difference testing or other tests, all designed around the particular problem or project. The studies are carried out under the direction of the AWRI specialist sensory group with extensive expertise and qualifications in this area, with close to 20 years experience in conducting sensory analyses.

All wines are assessed in blind tasting conditions using standardised sensory evaluation procedures. For example, the samples are presented to tasters in coded, covered XL5 (ISO standard) glasses, in random presentation order, with constant volume of wine in each glass, and the tests are carried out in the Institute’s purpose built sensory facility in isolated, temperature controlled tasting booths under constant lighting.

Technical quality evaluation – commercial acceptability and off-flavour assessment

This service is offered to allow an independent, dispassionate evaluation of a wine’s attributes, indication of quality level and presence of off-flavours. It should not be considered to be as rigorous as more formal quantitative sensory tests such as difference testing.

Each wine submitted is assessed independently by at least five trained, highly experienced AWRI judges. Judges qualify for this panel on the basis of extensive experience in wine sensory assessment and quality judgement, including:

1. professional academic qualifications;
2. wine industry professional experience;
3. successful completion of the AWRI Advanced Wine Assessment Course;
4. previous performance in wine descriptive and discrimination sensory tasks, including research sensory panel studies;
5. extensive technical wine knowledge including fault assessment; and
6. following a probation period on the technical panel of at least three months before a review of performance.

Performance of the judges for this panel is continually reviewed.

Some information regarding the nature of the sample is provided to the judges, notably the grape variety, wine style if appropriate, and vintage. The tasters are instructed to comment in detail regarding the appearance, aroma and palate attributes of a wine, and to score the wine using the 20 point quality scoring system as used in Australian wine show judging. All tasters’ comments and scores are provided in a written report. The panel is also instructed to identify and rate the intensity of any perceived off-flavours on a category intensity scale from zero to nine.

Note that judgement of wine quality and perception of a wine’s characteristics in this way is subjective, depending on the individual judge’s physiology, background and style preferences. The information provided from the technical panel assessment, using a small number of expert judges on a single occasion, using their own choice of comments, is not amenable to statistical analysis.

More formal sensory analytical tests such as the difference testing procedure are described below. Tests can require a relatively large volume of wine: please contact us for more details.

Taint/off-flavour rating

For projects where a set of samples might be involved, including some which may be tainted, have winemaking faults or other off-flavours, an intensity rating test is available. This taint/off-flavour rating test is commonly used to determine the incidence of faults in bottled wine batches. This may be done following a preliminary technical quality evaluation (see above) of a small number of samples. A panel trained to recognize and score the attributes related to cork taint, oxidation, Brettanomyces/Dekkera flavour, and reduction provides quantitative data that can be analysed statistically and related to compositional analyses such as TCA or 4-EP if required. Blind repeats and control samples are used to ensure high quality data is produced.

Difference test assessment

When there is a question as to whether two wines are detectably different in their sensory characteristics, a difference test procedure such as a duo-trio, triangle, or paired comparison test can be carried out. These sensitive tests using a large panel of judges are normally undertaken when there may be a subtle difference between two wines. These differences might not be detected from other sensory tests, and may, for example, be due to an effect of a winemaking procedure on two lots of wine, differences in storage conditions, or when a batch of wine is thought to have developed a taint or off-flavour, especially when a control is available.

Both the triangle test and the duo-trio test involve a judge selecting one sample from three that is different. Which test is recommended will depend on the sample type and nature of the potential difference. A paired comparison test can be used when there is a known characteristic to be tested, for example level of bitterness or intensity of mercaptan aroma. The judge is asked which of two coded samples is perceived to be higher in the specified character.

This type of test can be useful to carry out after an initial technical quality evaluation.

Descriptive analysis

The powerful method of descriptive analysis produces a sensory profile for a set of wines from replicated scoring of a set of attributes by a panel of sensitive and trained judges. Sensory profiles are highly valuable in applications such as shelf life or storage studies; comparison of a set of treatments, especially with a standard, or to relate a wines’ perceived attributes to instrumental measures or consumer preference. Of the sensory procedures offered, this type of test is the most complex to conduct and provides the greatest amount of quantitative information.

Consumer acceptability

Consumer testing, measuring liking for a set of wines using selected but untrained individuals, allows an understanding of the influence of sensory properties on acceptance. A relatively large group of consumers from outside the AWRI is recruited based on demographic and wine consumption criteria and rating for degree of liking is carried out under controlled conditions. This type of study is especially useful to investigate treatment effects such as yeast strain or storage time on liking, and as a preliminary to large scale consumer testing for product development.

Sensory evaluation

Technical quality evaluation – commercial acceptability and off-flavour assessment

Please contact us for more details and pricing for difference testing (duo-trio - constant reference, balanced reference - triangle, paired comparison), taint/off-flavour rating, descriptive analysis and consumer testing.

For more information, contact Customer Service at The Australian Wine Research Institute. E-mail the Analytical Service or telephone 08 8303 6600, facsimile 08 8303 6621.