A guide to proficiency testing of professional tasters
Until you've assessed the competence of your professional tasters you can't be sure they'll perform at the level you need them to. How can you go about assessing your tasters' abilities to identify flavours, scale their intensity, and perform in routine tasting?
Experience and skill sometimes go hand in hand, but that should never be taken for granted. Even the most experienced of tasters can perform badly. Lack of concentration, illness, medication - they can all conspire agains the best efforts and skills of tasters.
If you are going to rely on the results produced by your sensory analysis programme, you have to be able to rely on the performance of your tasters. Taster competnce cannot be taken for granted. You have to measure it in an objective way.
Poor taster performance can result in:
- Poor discrimination between samples
- Confusion of one flavour term with another
- Differences in how assessors use intensity scales to rate different samples or attributes
- Differences in how assessors perceive the nature of one or more attributes
- Inconsistencies in assessments
The primary reason for validating the performance of professional tasters is simple: if the skill is important to your success, then it is important that the skill is real and not just claimed. You wouldn’t employ just anyone to do your Company accounts – you would look for evidence of accounting skill, in the form of qualifications, for example. Why should you take a different approach in the case of tasters? To coin a phrase, if a job’s worth doing, it’s worth doing well!
Desired taster competences
Tasters must be able to carry out their evaluations to the best of their ability, as they have been trained to do, and in a repeatable way.
Depending on the types of assessments they will be asked to undertake, assessors will have to do one or more of the following:
- Assess two or more samples together to determine whether they can detect differences between them - they will use various 'difference' taste tests to do this - for example Duo-Trio and Triangular tests.
- Identify taints or off-flavours present in samples - it is impossible for a taster to identify a taint or off-flavour which they have never tasted before. Training in potential problem flavours before they arise in production situations is essential.
- Assess the strength of one or more attributes in samples - this may be done using various magnitude estimation techniques and scaling assessment methodologies
- Rank samples in order of the intensity of one or more attributes - this can be done using ranking and rank-rating tehniques
- Evaluate the degree of deterioration in sample flavour after storage under controlled conditions (shelf-life assessment) - there are various options available here; some based on difference tests, some based on ranking or rating tests, others based on descriptive profilng techniques
- Generate an informal flavour description of one or more samples
- Assess the flavour quality of one or more samples
- Carry out a full descriptive analysis on one or more samples using as many as 50 different attributes and a common intensity scale
Reasons for validating taster performance
There are a variety of reasons why we might want to validate the performance of professional tasters. These include:
- Screening and selection of new tasters
- Measurement of the performance of individual tasters and trainees
- Measurement of the performance of flavour panels
- Measurement of the effectiveness of training programmes
Types of sensory proficiency tests applicable to professional taste panels
There are several ways in which assessor competence in the various skills related to sensory analysis can be assessed:
- Tests of discrimination skills using samples with defined degrees of difference
- Tests of flavour identification skills using samples to which specific flavours of known concentration and purity have been added
- Tests of scaling ability using sets of samples which span a range of intensities for a single flavour attrribute
- Statistical analysis of replicate evaluations of samples by assessors in routine taste sessions
Proficiency testing can be carried out separately from routine taste sessions or can be based on analysis of routine test results.
Several 'ring analysis' or 'inter-collaborative' proficiency testing schemes have been implemented in different industries to assess taster competence. Arguably the largest of such schemes has been those developed and run by Cara Technology (until recently, in co-operation with FlavorActiV Limited) for the beer industry. AROXA beer taster validation schemes employ stabilized reference beer flavour standards to generate beers with consistent sensory properties.
Two types of sensory proficiency testing schemes available from AROXA
AROXA offers two types of proficency testing schemes for professional taste panels. The first assesses the ability of tasters to identify flavour attributes presented at low levels in samples. The samples presented to assessors differ from a reference sample in the intensity of a single flavour attribute such as diacetyl, isoamyl acetate or sourness. The flavour is delivered into the sample by means of nanoencapsulated certtified reference flavour standards which are safe to smell and taste.
Assessors have to identify the attribute which has been added to each of six samples, choosing from a list of 30 - 50 possible flavours. The list of flavours presented can be customized to suit the particular customer application.
The results of each test are entered into a secure database via the internet using a web browser.
The second type of assesssment relates to scaling ability. Samples are presented to assessors which span a range of intensities for a single flavoour attribute. Replicates as well as control samples containing no added flavour are included in the test set of nine samples. Assessors have to first rank the samples in order of intensity before rating the intensity of the added flavour in the samples.
In the case of both types of assessment the data can be analysed in a variety of ways to provide information relating to multi-National companies, country operations, individual taste panels, and individual assessors.