Sensory-Evaluation

Sensory testing methods

• Sensory testing allows us to evaluate the effect of different foods on our senses

• Results from these tests can be used in product development and are key in maximising sales of certain products

Preference tests

• Preference testing is used to assess and compare consumer preferences for different food products to determine whether food is acceptable to the consumer

  • Consumers may be asked to taste test products and comment on

    • taste

    • texture

    • aroma

    • appearance

  • They may then provide an overall evaluation which will be used to guide future product development

  • Preference testing is subjective as it depends on the consumer’s personal opinion

  • A large group of consumers should be tested to maximise the validity and reliability of the data collected

• The paired preference test is one form of preference testing

  • The tester is given samples from two different food products

  • Samples are given a random number and testers are asked which one they prefer

  • A conclusion is made about the products based on which one is preferred by the most testers

• Hedonic ranking is an alternative way to test preferences

  • The objective of the test is to determine the extent to which the tester likes or dislikes a product

  • Testers will be given multiple samples and asked to rank them based on a level of consumer liking

  • Different scales for hedonic tests can be used

    • A five-point scale might include options such as

      • dislike very much

      • dislike

      • neither like nor dislike

      • like

      • like very much

    • A nine-point scale might include

      • like extremely

      • like very much

      • like moderately

      • like slightly

      • neither like nor dislike

      • dislike slightly

      • dislike moderately

      • dislike very much

      • dislike extremely

  • A statistical test could then be used to determine whether there are significant differences between the ratings given for each product

Discrimination tests

• Discrimination tests are used to determine whether there are perceptible differences between two or more different foods

• The aim is to determine whether there are any sensory differences rather than to determine a degree of liking

• The triangle test is the main type of discrimination test

  • The tester is given three samples

  • Two of the samples are the same and one is different

  • The tester is asked to identify the odd one out

Grading tests

• Grading tests are used to give food products a rank, a rating and a profile

• These tests measure the extent of a particular sensory property

• There are three types of grading test

  • Ranking tests: Testers are asked to order samples based on the strength of a particular property e.g. the sweetness of a food

  • Rating tests: Testers are asked to rate how much they like/dislike a particular sensory property in a number of similar foods

    • Alternatively, the tester may be asked to test several properties of one type of food

  • Profiling tests: Testers are asked to rate products against how well a certain descriptive word applies e.g. crispy, chewy or moist

    • This allows a detailed description of the product to be developed

Setting up a taste panel

• A taste panel is made up of:

  • Trained testers who are trained to evaluate specific sensory attributes

    • Trained testing panels are used for quality control and detailed sensory analysis

  • Untrained consumers who represent the target market

    • A consumer testing panel is used for acceptability and preference testing

• The environment for testing must be carefully set up and controlled to ensure the collection of valid data

  • Controls in the test environment should be:

    • simple with no distractions

    • carefully lit (with coloured light) to avoid influences of colour on the testers

    • a large enough space to separate testers from each other

  • Testers should be:

    • non-smokers

    • in good health and free from any illnesses

    • not have any strong opinions on likes and dislikes which may influence their responses

  • Food samples should be:

    • random

    • anonymously labelled

    • the same size

    • fresh

  • The testing equipment should be prepared as follows:

    • identical equipment (size, shape, material) to deliver each sample being presented

    • neutral food carriers should be used if the food type is usually eaten in that way e.g. bread or crackers

      • the carrier must not have a flavour which will interfere with the product

    • water should be provided to cleanse the mouth in between samples

    • a rest period of 30 seconds should be given between samples