Chemistry, sensory, chemometrics and development capacity
Access to advanced and highly specialised equipment and staff is essential for the high quality, multidisciplinary research which is a trademark of the AWRI, and for collaborative projects with other research organisations and industry partners. This is especially the case where projects require access to highly specialised technical and scientific skills, such as those of a synthetic organic chemist or sensory scientist. In addition, the provision of sensory analysis requires a pool of screened, trained and experienced sensory assessors operating under the leadership and supervision of a professional sensory specialist who tracks performance and assesses training needs. Before and after a sensory experiment, highly specialised skills in experimental design, software for the acquisition of complex sensory data, data analysis and interpretation are required. Similarly, complex chemical analysis requires specialised analytical chemists with expertise in modern chromatography and mass spectrometry as well as skills in method development, optimisation and validation to produce reliable, accurate and precise data, and to ensure instrumentation remains operational around the clock.
Sensory science involves great care in experimental design; panel recruitment using qualified judges; careful control of all aspects of the test procedure; leadership and people skills to ensure judges are highly motivated and unbiased; and a high degree of knowledge of aspects of psychology, physiology, statistics and wine science. The AWRI runs four main types of sensory testing: an expert technical quality panel; trained sensory descriptive analysis; difference testing, and consumer hedonic testing.
The technical quality panel provides detailed tasting notes and fault scores for wines submitted through AWRI helpdesk investigations, as preliminary screenings for research projects, and for clients of AWRI Commercial Services. During 2015/2016, the panel evaluated 262 wines, as well as numerous training samples, and more than 400 wines in preliminary bench tastings. The 17 judges on this panel have extensive general wine tasting expertise and technical knowledge of wine production and composition, with most having commercial industry experience, formal oenology qualifications and/or having completed the AWRI Advanced Wine Assessment Course. All judges, no matter how experienced, are required to pass a probationary period before being admitted as reportable judges.
A large study was completed involving 108 wines assessed for closure-related faults, as well as several studies with a specialist smoke taint panel, including a set of wines with a project conducted by DEDJTR Victoria to determine the severity of smoke taint and the links to smoke compounds.
In 2015/2016, 25 major descriptive analysis studies were completed using the AWRI’s highly trained part-time external sensory panel – the highest number of such studies ever completed in a year at the AWRI, surpassing last year’s record. Eight new sensory judges were recruited in January/ February, allowing two panels to be run per day during periods of high demand to ensure high quality sensory data could be obtained to meet project timelines. The new panellists were screened for sensory acuity and skill, and were given training and experience in sensory methodology prior to their assimilation into the existing panel. The studies included two large projects with SARDI assessing the effect of grapevine clone on wine flavour, with Chardonnay and Shiraz wines made from grapes from vineyards in Victoria, South Australia and Western Australia.
Difference testing, generally using the method of triangle testing, is also an important sensory technique to find if a treatment has had a perceptible effect on wine aroma or flavour. Approximately 50 AWRI staff are screened and qualified to perform this task, usually assessing two or three sets per session. Twelve tests were completed.
Consumer testing for degree of liking was conducted fora major study on ‘green’ flavour in Shiraz wines, involving more than 100 consumers. Projects were also completed for commercial clients to obtain customer feedback on product perceptions, and investigations were finalised regarding the validity of a ‘discrete choice’ methodology for understanding Chinese consumers’ wine preferences.
In addition, previous work completed with UniSA on “Understanding Chinese sensory preferences for varied wine styles and the language used to describe them” has resulted in an Australian Wine Flavours Card produced by Wine Australia, to assist exporters, retailers and consumers to match wine flavours with useful descriptive words.
Spectral measures of grape and wine composition
The application of mid-infrared, near infrared, ultraviolet and visible spectroscopy continues to be important for research projects and for contract studies at the AWRI. Fingerprinting the spectral signature of samples for authentication purposes has been a key element of studies over the last 12 months. In addition, assistance has been provided to a University of Adelaide project led by Prof. Eileen Scott for rapid assessment of powdery mildew.
Synthetic organic chemistry
The synthesis of important analytical standards and other chemical compounds required for mechanistic studies or sensory investigations is of great benefit to the AWRI’s research. When compounds are not available commercially, or are prohibitively expensive, the ability to produce them in-house is invaluable. Projects requiring synthesised compounds have included those investigating smoke taint, in-mouth flavour release and sulfur off-flavours.
Aroma compound analysis
State-of-the-art analytical instruments, including GC-MS and LC-MS, are carefully looked after to ensure they are in optimal operational order and capable of being used continuously in periods of high demand to give timely results. Analytical methods for targeted aroma compounds were applied in many projects. Important compounds such as norisoprenoids (‘fruity’, ‘violets’, ‘kerosene’), thiols (‘tropical fruit’, ‘struck match’, ‘box hedge’), monoterpenes (‘citrus’, ‘floral’), rotundone (‘pepper’), oxidative compounds (‘honey’, ‘bruised apple’) and C6 compounds (‘green’, ‘grassy’) were quantified in more than 500 samples. These analyses are also available on a fee-paying basis through AWRI Commercial Services.
Metabolomics (South Australian Metabolomics Facility)
The AWRI established the South Australian node of Metabolomics Australia in 2008 with funding from Bioplatforms Australia and the South Australian State Government that enabled the purchase of five dedicated GC-MS and HPLC-MS instruments. The South Australian Metabolomics Facility is part of a national network with partners in WA, Victoria and Queensland who support and service private and public sector R&D in their respective states. It operates as a collaborative service platform, providing access to infrastructure and specialist expertise to academia and industry across all interested sectors.
In 2015/2016, the facility delivered more than 5,000 sample analyses for researchers and other clients across the agriculture, biomedical and environmental sectors. A new LC-MS method was developed to analyse carotenoids in grapes and another method was set up to detect 34S-labelled H2S to monitor related metabolite pathways during grape fermentation. The facility has provided assistance in project work and instrument training to a number of visiting international students from Germany and Bordeaux. The platform is advancing in the area of bioinformatics for metabolomics with a unique automated data processing workflow developed using the R programming language. This workflow is tailored for metabolomics analysis of data captured on both GC-MS and LC-MS platforms and is useful for the wider metabolomics community.