1. Sensory Perception and Evaluation
Module 2

2. Importance!

3. What is sensory analysis?
“Sensory evaluation has been defined as a scientific method used to evoke, measure, analyze, and interpret those responses to products as perceived through the senses of sight, smell, touch, taste and hearing.”

4. Objectives Identify aspects of food selection based on the five senses
Understand the role sensory perception plays in food selection
Evaluate food using basic sensory attributes and scales
Select an appropriate testing method to obtain needed information

5. Sensory Perception
When most people choose a particular food, they evaluate it using the sensory perceptions:

6. Sight
The first impression of food is created by its appearance, which is received by the eye:
Serving size
Shape, color, consistency
Presence of defects

7. Color can denote… Ripeness green vs. yellow vs. black banana Strength
Almost white vs. brown chocolate milk
Degree of heating
Red vs. brown bulgogi
Flavor
Orange vs. red candy

8. Food Presentation
The combination of food on a plate, in a grocery store display, or at a restaurant also contributes to or detracts from its appeal.

9. Smell / Odor
Smell is almost as important as appearance when people evaluate a food item for quality and desirability.
Most people can differentiate between 1,000 to 2,000 different “smells”
E.g. Mozzarella vs. Provolone

10. Odor/smell Odor Detection
Aids in the evaluation of quality and desirability
Thresholds dependent on product/chemical/person
Odor adaptation
Volatile molecules
Olfactory patch
2.5 cm2 in humans
12.5 cm2 in cats!
Fruits – do they smell ripe and characteristic of the fruit, meats do they have any off-odors, oils (rancid)
What is detection threshold?
Adaptation – Odor is strong but as time goes by you become adapted to the smell. Your home, perfume
Volatile – hot apple pie (smell great, travels down hall and into other rooms vrs cold apple pie (maybe you smell it as you eat it), more intense
As molecules travel through air, they reach olfactory epithelium in upper part of nasal cavity. Only volatile molecules in form of gas carry odor, heat converts into gas

11. Taste
Taste substances must be dissolved in saliva to be detected by the taste buds.
Taste buds are located all over the mouth, but mostly on the tongue.

12. Chemical Basis of Taste Stimuli
Sweet
The sweetness of sugar comes from the chemical configuration of its molecule.
Sour
Related to the concentration of hydrogen ions (H+), which are found in the natural acids of fruits, vinegar, and certain vegetables.
Bitter
Imparted by compounds such as caffeine (tea, coffee), theobromine (chocolate), and phenolic compounds (grapefruit and vegetables).
Salty
Comes from salt ions [Na+] in sodium chloride (NaCl) or other salts found naturally in some foods.
Umami
Comes from monosodium glutamate (MSG) and other compounds – brothy, savory taste

13. Taste Interactions
Each item used in food preparation contains a number of compounds, and bringing these items together creates new tastes when all their compounds interact.
Examples:
Sugar: decreases sourness, adding sugar to yogurt makes it less sour
Monosodium glutamate (MSG): Enhances flavor in soup or stew and on snack foods

14. Other Sensations - Trigeminal
Sensations from chemical irritation (with food these usually occur in the nose and mouth)
Examples:
Astringency
Burn (e.g. from peppers – not temperature)
Metallic
Cooling (e.g. from mint – not temperature)

15. Flavor Taste and flavor are not synonymous terms.
Flavor is the combined sense of taste, aroma, and trigeminal sensations.

16. Factors Affecting Taste & Flavor
Person
Temperature of the product
Fat in product
Color of the food
Time of day
Hunger
Consumption patterns
Medication
Sickness

17. Touch
The sense of touch – inside the mouth or by the fingers – conveys a food’s tactile, or physical properties:
Texture
Consistency
Temperature

18. Hearing/Sound
The sounds associated with foods can play a role in evaluating their quality.
Examples:
Tapping of a watermelon to determines its ripeness/sweetness
Crunchiness of crackers/chips
Sizzling of steak on the grill
Popping of popcorn
Fizzing of soda pop
Bubbling sound of a boiling soup

19. Purpose of Food Evaluation
The food industry uses an array of testing methods to measure the sensory factors in food selection and to evaluate food quality.

20. How is food evaluation used?
New product development
Product improvement
Develop “Gold Standard”
Ingredient changes
Cost reduction
Quality control/assurance
Gauging consumer acceptance
Claims tests

21. Type of tests Analytical Affective Difference/discrimination
Descriptive
Affective
Acceptance/preference
Consumer attitude

22. Two basic types of tests 1) objectivemeasurement of a specific attribute or product differences
Difference tests
Duo-trio
Triangle
Descriptive tests
aroma, flavor, texture, appearance
describe product using attributes (terms)
rate intensity of the attribute on a scale

23. Difference Testing

24. Descriptive panelists at work

25. Descriptive Ballot Surface Appearance
Color
Surface Shine
Texture
Firmness
Terms, Definitions, and References
Color Light to dark evaluation of a brown color of the sample.
Reference: Porter Paints Color Chip = 9.0
Surface Shine The amount of gloss or shine perceived on the surface of the product.
Reference: Land O’Lakes Sour Cream = 10.0
Firmness The force required to compress product between the tongue and palate, using constant steady force. Use ½
teaspoon of product. (Not at all Firm to Extremely Firm)
References: Land O’Lakes Sour Cream = 5.0
Philadelphia Fat Free Brick Cream Cheese = 9.0

26. 2. Affective - acceptance or liking of specific attributes or products
Consumers are evaluated for their preferences or acceptance of a product rather than their evaluation of differences.
Consumer preference
Prefer one product or the other
Consumer acceptance
Rate how much you like the pizza

27. Affective Test Ballot

28. Focus Group Testing
Qualitative testing with the purpose to develop insights and direction.
Researchers are interested in
Attitudes
Opinions
as they relate to products, services, and concepts.

29. Applying Sensory Evaluation to Food Science Everyday
Things to consider when tasting food:
Focus on the characteristics of the food
What’s good quality, poor quality
Don’t focus on what you like
Questions to ask:
Would you be proud to serve the food?
Is the product the best quality you can get, if not, then how can you make it better quality?

30. Coffee Wheel

31. Chocolate Wheel

32. Olive Oil Wheel