Lesson 7 - Sensory Analysis SAQ

**Explain how we avoid bias in sensory analysis.

Response:

Some assessors tend to rate the first beer highest and the last beer lowest, so randomisation of the samples means all assessors have a different first and last sample. Likewise, sensory fatigue becomes a factor, so ensuring samples towards the end are different avoids this impacting on one sample. The impact of sensory fatigue is also avoided by limiting the number of samples assessed, particularly if the beer is strongly flavoured or has a lingering aftertaste. Crackers and water can help in this instance. Another means of preventing bias from stronger-tasting beers is to place these last in the tasting so they do not affect subsequent samples.

In triangle testing there is a tendency for assessors to pick the middle sample as the sample that is different. Randomising sample delivery is necessary to avoid this tendency affecting results.

The facilities for tasting are designed to prevent bias from the environment. Any aromas present will affect the assessor’s perception of the beer so the tasting area and the facilities must be odour free. Isolation booths are designed to prevent other assessors’ reactions to beer influencing an assessor’s marks. Darker beers tend to be sweeter than light beers and there is a tendency for assessors to mark beers differently if they can see the colour; dark-coloured glassware prevents beer colour affecting evaluations of taste on the basis of expectation.

Randomly chosen codes are used to prevent assessors rating the beer with their favourite number higher than the others or production staff trying to recognise batch numbers.