Sensory Evaluation: Setting Up Tests

This lesson covers the practical aspects of setting up and conducting sensory evaluation tests, including taste panels, controlled conditions and evaluating sensory qualities, as required by the AQA GCSE Food Preparation and Nutrition specification (8585), section 3.5.

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Setting Up a Fair Test

For sensory evaluation results to be reliable and valid, the testing conditions must be carefully controlled. Without controlled conditions, results may be biased or inconsistent.

Key Principles of Fair Testing

Principle	How to Achieve It
Consistent samples	Each taster receives the same amount, at the same temperature, presented in the same way
Random coding	Samples labelled with random three-digit numbers (e.g., 247, 391, 582) — not letters or names that might bias the taster
Controlled environment	Testing in a quiet, well-lit room free from distractions
Independent assessment	Each taster works individually without discussing opinions with others
Palate cleansing	Tasters cleanse their palate between samples
Sufficient tasters	A large enough sample of tasters to produce meaningful results
Random order	The order in which samples are presented varies between tasters to avoid order bias

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Taste Panels

A taste panel is a group of people who evaluate food samples. There are two main types:

Untrained Taste Panel

Feature	Detail
Who	Members of the general public or potential consumers
Training	None — they give personal opinions based on their own experience
Best for	Preference tests (paired preference, hedonic) and market research
Size	Typically 30–100+ people for reliable results
Advantage	Represents real consumer opinion; easy to recruit
Limitation	Inconsistent — different people interpret scales differently; personal biases

Trained Taste Panel

Feature	Detail
Who	Selected individuals who have been trained in sensory evaluation techniques
Training	Trained to recognise specific flavours, textures and aromas; calibrated in their scoring
Best for	Discrimination tests (triangle test) and grading tests (rating, profiling)
Size	Typically 6–12 people
Advantage	More consistent and objective results; can detect subtle differences
Limitation	Expensive and time-consuming to train; may not represent typical consumer opinion

flowchart TD
    A["Taste Panels"] --> B["Untrained Panel<br/>30-100+ people"]
    A --> C["Trained Panel<br/>6-12 people"]

    B --> D["Preference tests<br/>Consumer opinion<br/>Market research"]
    C --> E["Discrimination tests<br/>Quality control<br/>Sensory profiling"]

    style B fill:#3498db,color:#fff
    style C fill:#e67e22,color:#fff

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Controlled Testing Conditions

The Testing Environment

Feature	Requirement	Why
Testing booths	Individual booths or partitions to separate tasters	Prevents tasters influencing each other through facial expressions, comments or body language
Neutral lighting	White or neutral lighting (or specified colour)	Coloured lighting can mask the true appearance of food; red lighting is sometimes used to disguise colour differences when testing flavour only
Quiet environment	Minimal noise and distractions	Distractions affect concentration and the ability to focus on sensory qualities
Room temperature	Comfortable, consistent temperature	Extreme temperatures affect taste perception
Odour-free	No strong smells in the testing area	Background odours interfere with aroma assessment
Clean surfaces	All surfaces and equipment clean and neutral	Residual flavours or smells from previous tests could contaminate results

Sample Presentation

Feature	Requirement	Why
Identical containers	All samples in the same type, colour and size of container (usually white)	Different containers may suggest quality differences
Random three-digit codes	Each sample labelled with a random number (e.g., 427, 815)	Prevents bias from alphabetical or numerical order; letters like A, B, C imply quality ranking
Equal portions	Same amount of each sample	Different amounts might suggest one is more important or better
Same temperature	All samples served at the same temperature	Temperature affects flavour perception — warm food tastes different from cold food
Same preparation	All samples prepared using the same method and equipment	Variations in preparation could introduce differences unrelated to the test variable

Palate Cleansers

Between tasting each sample, tasters should cleanse their palate to remove residual flavours:

Cleanser	When Used
Plain water	Standard palate cleanser; room temperature; most common
Plain crackers or bread	Neutral flavour; absorbs residual oils and flavours
Apple slices	Effective between strongly flavoured samples
Warm water	Can be more effective than cold water for fatty or oily foods

The taster should:

1. Taste the sample
2. Record their assessment
3. Cleanse their palate (water, cracker)
4. Wait briefly
5. Taste the next sample

Exam Tip: Always mention palate cleansing and coded samples when describing how to set up a sensory test. These are key marks in exam answers. The reason for random three-digit codes (not A, B, C) is to prevent order bias — tasters may assume the first sample (A) is the "standard" or the best.

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Evaluating Sensory Qualities

When evaluating food, tasters assess multiple sensory characteristics:

Appearance