Food manufacturers and retailers often use sensory evaluation in order to help them to know what consumers think of their products. They may also carry it out to ensure that all the food produced by a production line is identical.
This testing may take place at various stages of the production process and may involve testing raw ingredients, after developing new dishes, after they have been modified or after they have been stored.
The food will be tested using organoleptic factors, meaning that they are using our different sense organs. Such as:
- Texture (mouthfeel)
- Taste or flavour
- Appearance or colour
- Smell or aroma
In order to ensure that sensory testing is considered to be 'fair', it is important that conditions are carefully controlled.
This will involve:
1. Sipping water between each sample to remove the taste of the previous food.
2. Using separate booths so that testers are not influenced by each other.
3. Labelling food with numbers or letters so that the tester does not recognise a brand name.
4. Having a well-lit room with the minimum of noise and smells.
5. Using clean cutlery and utensils for each sample.
6. Sometimes using blindfolds (blind-testing) so that the tester if not influenced by the appearance of the food.
7. Each sample of food being the same size.
8. Having a minimum of 6 testers.
Testers must not be:
- Suffering from a condition, which would affect their taste (for example, smoking, a heavy cold, or taking strong medication).
- Allergic to foods or ingredients.
1. Difference or Discrimination Tests
Two or more samples are compared at a time in order to find out if there is a difference between them.
Paired comparison tests: Pairs of food samples are tested and testers are asked to say if there is a difference between them in relation to a particular characteristic, such as saltiness or crunchiness.
Triangle tests: Three samples are presented to testers, but two of them are identical. The testers are asked to identify the 'odd one out'. This test is useful for comparing different brands of the same product (for example, tomato ketchup) or for ensuring that all batches from a production run are identical.
2. Grading Tests
Food samples will be tasted and then placed in order to reflect a particular characteristic - for example, sweetness, or a personal preference.
A Hedonic Scale is a very simple way of recording what a tester thinks of a product?
Testers are asked to tick underneath the face which best describes how they feel about the product.
Rating tests: Testers rate a product using either a 5, 7 or 9 point scale.
1. Extremely wet
2. Very wet
3. Moderately wet
4. Slightly wet
5. Neither wet or dry
6. Slightly dry
7. Moderately dry
8. Very dry
9. Extremely dry
Ranking tests: Samples that are coded are given to a tester in a random order. Testers are asked to rank the samples in order of preference using codes or symbols rather than numbers. A minimum of 10 testers are needed to produce results, which are both reliable and informative.
A star with 8 points is labelled with words which describe some sensory characteristics of a product. A tester is then asked to place the food sample on a scale of 1 to 5 for each characteristic. These results are then plotted onto the star. It is possible to compare similar products - for instance, two types of biscuits or fruits - by plotting them on the same star profile.
Test yourself with the following interaction...
Drag the words in the yellow panels into the corresponding gaps so that they describe the three different foods. Mark your answer to see how you got on: