Sensory evaluation Teachers guide
Welcome What is sensory evaluation? Sensory evaluation is a scientific discipline that analyses and measures human responses to the composition of food and drink, e.g. appearance, touch, odour, texture, temperature and taste. In schools it provides an ideal opportunity for students to evaluate and give feedback on their dishes, test products and experimental designs. The precise way in which sensory evaluation is conducted, along with the different tests and sensory language used, needs to be taught. This will help students to understand the process and develop their sensory vocabulary. It also means that students will record and generate evaluative feedback to support their work. Why use sensory evaluation? Sensory evaluation can be used to: compare similarities/differences in a range of dishes/products; evaluate a range of existing dishes/food products; analyse food samples for improvements; gauge responses to a dish/product, e.g. acceptable v unacceptable; explore specific characteristics of an ingredient or dish/food product; check whether a final dish/food product meets its original specification; provide objective and subjective feedback data to enable informed decisions to be made. This resource In this guide you will find details of how to set up and conduct a range of different sensory evaluation tests. This online resource comprises: 1 x Teachers guide ; 1 x The senses and food PowerPoint presentation; 1 x Umami PowerPoint presentation; 8 x photocopiable worksheets; 17 x Excel templates these allow students to record, model and display their results easily and accurately; 2 x posters (as PDFs); 1 x parent/carer letter. 2
Organising sensory tests How to perform sensory evaluation 1. Decide on the type of test you want to perform suitable for what you want to find out. Preference test - asks whether people like or dislike a product, e.g. hedonic scale Discrimination test - asks people to describe a particular attribute of a product, e.g. paired comparison test. 2. Find a clear area to hold the sensory test. Try to make sure that it is away from noise and cooking smells which may distract the people taking part in the test. This can be difficult in a busy classroom. Some schools have created areas within the food room for tasting to be held. 3. Place as many samples in serving containers as there are people taking part in the test. Code each sample with a random number, letter or symbol. 4. Check that you have enough glasses of water for the people taking part. This is for tasters to cleanse their palette after tasting each food sample. 5. Make sure the people taking part know what is expected from them, i.e. they understand which test they are taking and what they have to do. 6. Ask each person to taste one sample at a time, and record their responses. Allow time between samples so that tasters can record their opinions. Tasting kit Some schools have created a tasting kit, which has all the necessary equipment for students to undertake sensory evaluation. A typical tasting kit could contain: serving spoons; teaspoons; small, plain white pots, cups and plates; paper towel; rubbish bags, cutlery; labels; pens. A plentiful supply of different sensory evaluation worksheets, or easy access to the ICT templates, could also be made available. 3
Types of tests Preference Tests These types of tests supply information about people's likes and dislikes of a product. They are not intended to evaluate specific characteristics, such as crunchiness or smoothness. They are subjective tests and include hedonic, paired comparison and scoring. Hedonic 1. Prepare the food samples. 2. Ask each taster to taste each sample in turn and tick a box, from '1 Dislike Very Much' to '5. Like Very Much' to indicate their preference. This is a 5-point-scale. Sometime a 9-point-scale is used. 3. The taster may also wish to make remarks about the products appearance, taste, odour and texture. 4. Analyse the results. Which sample received the highest/lowest scores? Which sample was preferred? Note: The same worksheet can be used for all the tasters. This will reduce photocopying and paper waste. (However, other tasters scores/comments could influence each other.) Hedonic chart PDF worksheet Hedonic chart Excel template for 3 dishes/products Hedonic chart Excel template for 4 dishes/products Hedonic chart Excel template for 5 dishes/products Paired Comparison Test (Preference) 1. Prepare two samples of the dish you wish to test. 2. Ask each taster which dish they prefer. 3. Record the response from the tasters. Paired comparison test PDF worksheet Paired comparison Excel template Scoring 1. Food samples are scored on a scale, between dislike and like. 2. Allow tasters to evaluate samples and score (place in order of preference). 3. Record their responses. Scoring PDF worksheet 4
Discrimination Tests These types of tests aim to evaluate specific attributes, i.e. characteristics of products (crunchiness). They are objective tests and include triangle, duo trio, ranking and paired comparison. Triangle test 1. Prepare three food samples, two of which are the same. 2. Arrange the samples in a triangle. 3. Ask the tasters to decide which of the samples is the odd one out. 4. Record the responses from the tasters. Triangle test PDF worksheet Triangle test Excel template Duo-Trio 1. Prepare three food samples, two of which are the same. 2. Using one of the two identical samples as a control, as the tasters to decide which of the other two remaining samples is the same as the control. 3. Record the tasters responses. Duo-Trio PDF worksheet Duo-Trio Excel template Ranking test 1. Decide on the attribute to be ranked, e.g. crunchiness. 2. Allow tasters to evaluate samples and place them in rank order according to the presence or absence of the attribute from very to not at all. 3. Record the responses. Ranking test PDF worksheet Paired Comparison Test (Discrimination) 1. Prepare two different samples of the food product you wish to test. 2. Compare one attribute, e.g. which one is smoother? 3. Record the response from the tasters. Paired comparison test PDF worksheet Paired comparison Excel template 5
Star charts/diagrams This type of test allows the intensity of the sensory attributes of a single food dish, or range of food dishes, to be recorded. The test is not intended to model general attributes such as 'nutrition', 'cost' or 'appearance', as they are more complex and are better dealt with in other ways. 1. Choose 8 attributes that describe the characteristics of the product, e.g. crunchy, spicy, savoury or smooth. 2. Taste the food sample. Decide on the intensity for each attribute, using a scale from 0 to 10 (the higher the number, the greater the intensity). 3. Use the information to draw a star chart/diagram of the product's attributes. Note: Multiple products can be overlaid on the same chart, indicating sensory differences/similarities. Although the worksheet or template can be used to compare 1-5 dishes/products, they can also be used to gather information from 1 or more tasters about the same product. Star chart/diagram PDF worksheet Star chart/diagram Excel template for 1 dish/product (5 point scale) Star chart/diagram Excel template for 2 dishes/products (5 point scale) Star chart/diagram Excel template for 3 dishes/products (5 point scale) Star chart/diagram Excel template for 4 dishes/products (5 point scale) Star chart/diagram Excel template for 5 dishes/products (5 point scale) Star chart/diagram Excel template for 1 dish/product (10 point scale) Star chart/diagram Excel template for 2 dishes/products (10 point scale) Star chart/diagram Excel template for 3 dishes/products (10 point scale) Star chart/diagram Excel template for 4 dishes/products (10 point scale) Star chart/diagram Excel template for 5 dishes/products (10 point scale) 6
Classroom activities There are many opportunities where sensory evaluation activities can form part of lessons. At the start, you may wish to teach students the different types of tests, as well as the use of appropriate vocabulary. Here are some suggestions to get you started. Appearance As a starter activity, ask students to name 3 foods they would or would not eat. For each food, ask them to give reasons based on its appearance. Odour Think about words to describe different ingredients or food dishes/products. Use the Odour worksheet to explore different sensory words that could be used. You could provide samples of different ingredients for the students to smell, recording the odour for each. You could use: fresh basil, pesto, lemon or lime, chocolate, canned fish, lemongrass, spices. Another activity could include a range of different food samples being placed into containers. Carefully allow students to open each container, only to smell its odour (not to look inside). Can they name the food sample? Sound As a starter activity, write the name (or show an image) of an ingredient on the board. Ask students to suggest the different sounds they would associate with the ingredient. Do the associated sounds change as the ingredient is prepared, cooked or eaten? Taste To help support and extend students vocabulary development, organise tasting activities. These will help to students to use a range of different vocabulary to describe the foods that they taste. Different types of cheese or apples could be used. Umami Organise a umami tasting session. Use ripe tomatoes or cheese. Can pupils detect umami? It is a subtle savoury taste not sweet, sour, bitter or salty. General Set up preference and discrimination tests. Explain the difference between the tests to the students. Use The Senses and food and Umami PowerPoint presentations with your pupils. Ask pupils to complete the complementary worksheets, The Senses and food Notesheet and Umami Notesheet. As a starter activity, ask pupils to suggest different reasons for food choice and acceptability. Use the Food Choice and Acceptability poster as a stimulus. Sensory vocabulary To help students develop their vocabulary, use the Word bank and Sensory Vocabulary poster. You could cut out the words, and then allow students to use these to describe a range of foods. 7
Curriculum links Country England Northern Ireland Scotland Wales Opportunities for Sensory Evaluation Key Stage 3: Design and Technology 3. Range and content: h. healthy eating models relating to a balanced diet, the nutritional needs of different groups in society and the factors affecting food choice and how to take these into account when planning, preparing and cooking meals and products i. the characteristics of a broad range of ingredients, including their nutritional, functional and sensory properties. Key Stage 4: Design and Technology and Home Economics courses Examination specifications contain references to the sensory evaluation of ingredients and cooked dishes. Materials within this resource can be used to help support sensory development. Key Stage 3: Learning for Life and Work: Home Economics Although not specifically mentioned, aspects of sensory evaluation (tasting and testing) are important attributes of Home Economics from evaluating different dishes to understanding the needs and food choices of individuals. Key Stage 4: Home Economics Examination specifications contain references to the evaluation of ingredients and cooked dishes. Materials within this resource can be used to help support sensory development. Second and Third Health and wellbeing: Food and the consumer HWB2-34a / HWB3-34a Technologies: Food and textiles TCH-2-11a / TCH3-11a / TCH 2-11b Fourth Health and wellbeing: Food and the consumer HWB 4-34a Technologies: Food and textiles TCH 4-10b / TCH 4-11a / TCH 4-11b/ TCH 4-11c Key Stage 3: Design and Technology Range: Food 9. classify food by commodity/group and understand the characteristics of a broad range of ingredients, including their nutritional, functional and sensory properties Key Stage 4: Design and Technology and Home Economics courses Examination specifications contain references to the sensory evaluation of ingredients and cooked dishes. Materials within this resource can be used to help support sensory development. 8
Sources of further information Food a fact of life www.foodafactoflife.org.uk Japanese cuisine www.ajinomoto.com Umami www.umamiinfo.com Acknowledgement The Foundation would like to thank Ajinomoto and the Umami Information Centre for their advice and support in developing this resource. Food a fact of life 2010 9