Food Sensory Analysis

Fernando Pérez MuñozJune 2011

Agenda

• Day 1– Introduction to sensory– Color and appearance– Experiencing Jelly Beans– Sensory testing basics

• Day 2– Triangle testing– Student experiments

• Day 3– The five tastes– What is flavor?– Rediscovering Flavor

• Day 4– Rating tests– Food texture– Student experiments

DAY 1

Introduction to sensoryColor and appearanceExperiencing Jelly BeansSensory testing basics

Introduction to Sensory

What does this tell you?

Feel?

Taste?

Aroma?

Look?

Sound?

What does this tell you?

Man or Woman?

Age?

Social Status?

Type of Car?

Cost?

Introduction to Sensory

• What is Sensory Evaluation?– IFT Food Sensory Division

• “Sensory evaluation is the scientific discipline used to

evoke, measure, analyze, and interpret reactions to the

characteristics of food and materials as they are

perceived by the senses of sight, smell, taste, touch, and

hearing.”

Introduction to Sensory

• If Sensory evaluation utilizes the five senses…– What are the testing instruments?– Will measurements be qualitative or quantitative?– What could be some of the problems?– Is it possible to fix those problems?– Can those instruments be calibrated?

COLOR AND APPEARANCEIntroduction to Sensory

Color and Appearance

What is needed to perceive the world through your eyes?

Light Source

Object

Sight

What Characteristics can be Perceived Through Your Eyes?

• Stimulus– Color– Transparency– Shape– Size– Surface texture– Porosity– Surface wetness

• Interpretation– Flavor– Hardness– Wetness– Sponginess– Cohesiveness

What is Light?

• Electromagnetic waves (380 to 760 nm)

What is Light?

• RGB: Primary colors

What are Black and

white?

What is Light?

• Transmission, reflection and absorption

Light

Reflection

Absorption

Re-emission

Re-emission

transmission

Object Properties

• Physical state: solid, liquid, gas• Size• Surface roughness (gloss)• Color (pigments)

Object Properties

• Pigments– Primary pigments: CYM

Eyesight

• Eyes receive the stimulus• Information sent to the brain• Brain interprets data

– Based on past experience and associations• Reaction occurs

Factors Affecting Eyesight

• Iris – Light control• Lens - Focus• Retina

– Cones (gray levels)– Rods (color)

• Less sensitive• Capability lost at low light levels

• Past Experience

Factors Affecting Eyesight

• Carry-Over– The visual impression of the object remains for

a few seconds after the stimulus has been removed

Factors Affecting Eyesight

• Color Implications– Our mind has established links between colors

and their meaning– Such links are used when interpreting the data

received– Might lead to the wrong conclusion

Factors Affecting Eyesight

• Color Implications– What color comes to mind when you hear the

word “chocolate”?

Factors Affecting Eyesight

• Expectations– This is similar to the color expectation– The brain establishes links to speed up data

analysis– Such links or shortcuts might lead to wrong

interpretations

Factors Affecting Eyesight

• Cultural Expectations– More brain shortcuts…– These are dependent on the culture or

environment in which the person grew up

Factors Affecting Eyesight

• Metamerism– Different interpretation of the same stimulus

under different circunstances

EXPERIENCING JELLY BEANS

Introduction to SensoryColor and appearance

Demo #1 – What Color are Them?

• You will be presented with Jelly Bean samples.• When instructed, uncover and observe the

samples one at a time• Use the score sheet to write the observed

color of the samples

Demo #1 – What Color are Them?

• What happened!!!

SENSORY TESTING BASICS

Introduction to Sensory Color and appearanceExperiencing Jelly Beans

Basic Concepts

Data types• Qualitative

– Blue, red, yellow…– Round, square, oval…– Apple, melon, peach…– Yes, no– Same, different

• Quantitative– Integers: 1, 2, 3, 4…– Decimals: 3.5, 8.2…– Fractions: ½, ¼,…– Ordinal: 1st, 2nd, 3rd…– Multiples: double, triple…

Basic Concepts

Test types• Difference tests

– Compare 2 treatments to determine if they are different

• Attribute tests– Compare 2 or more

treatments to determine difference in the intensity of a specific attribute

• Descriptive test– Describe the attributes of

importance in a product and their respective intensities

• Consumer test– Determine preference or

acceptance of a product by consumers

Basic Concepts

• Testing protocol– Identify treatments– Prepare experimenter sheet and panelist score

card– Train panelists– Conduct experiment and gather data– Analyze data– Report results

Basic Concepts

• Test Controls– Environment

• Location, light, time of day, etc…

– Sample• Size, shape, matrix, presentation order, etc…

– Panelists• Smoking, health status, chewing gum, etc…

Basic Concepts

• Data analysis– Statistics makes it a science based field

• Instrumental analysis– Useful to establish relationships between panel

data and instrumental data

• Thresholds and limits

Basic Concepts

• Panel vs. Instruments

Demo 2 Time!!!

Questions?

Day 1 ends here…

DAY 2

Triangle testingStudent experiments

Review from Yesterday

• Sensory is a science that uses people’s senses to measure food properties

• If proper care (controls) are taken, data can be analyzed statistically to make decisions

• Instruments can also be used to measure properties– …but sensitivity can differ

Review from Yesterday

Test types• Difference tests

– Compare 2 treatments to determine if they are different

• Attribute tests– Compare 2 or more

treatments to determine difference in the intensity of a specific attribute

• Descriptive test– Describe the attributes of

importance in a product and their respective intensities

• Consumer test– Determine preference or

acceptance of a product by consumers

TRIANGLE TESTING

Difference Tests

• Objective– Determine overall

difference between two treatments

• No indication of the magnitude or direction of the difference

• Simplest tests

• Test types– Triangle– Two-of-Five– Duo-Trio– Same or Different– “A” – “Not A”– Different from control

Triangle Testing

• Application– Effect of change in process, ingredient, supplier,

etc.– Compare competitor products– Select panelists

Triangle Testing

• Test procedure– Prepare enough samples of

both treatments• Controls over samples

Look Closely…

Are they obviously different?

Triangle Testing

• Test procedure– Prepare enough samples of both treatments

• Controls over samples

– Present samples to panelists• Random presentation

– AAB, ABA, BAA, BBA, BAB, ABB

• Coded samples– Three digit random number

Triangle Testing

• Test procedure– Experimenter cheat sheet

Triangle Testing

• Score Card

Triangle Testing

Let’s Practice…

3

Data Analysis

• Data analysis based on the binomial distribution– Two possible outcomes: right or wrong

• Count the number of correct answers• Perform statistical analysis

– With equations (can be set in a worksheet)– Using tables (easier)

Data Analysis

Critical number of responses in a triangle test.

Meilgaard, M.C., B.T. Carr and G.V. Civille. 2006. Sensory Evaluation Techniques. Fourth Edition. CRC Press

STUDENT EXPERIMENTSTriangle Testing

Exercise 1: Triangle Testing

• Select your project1. Cheddar vs. Colby2. Pepsi ® vs. Coke®3. Pepín® vs. Holsum®4. Hormel® vs. Armour®5. Suiza Premium® vs. Tropicana®

• Prepare and execute triangle test• Analyze data

Exercise 1: Triangle Testing

• Project presentations and discussion

• Test objective

• Test type

• Number of panelists

• Controls

• Number of correct responses

• Conclusions

Final Comments

Questions?

Day 2 ends here…

DAY 3

The five tastesWhat is flavor?Thresholds and prejudices

Review of Concepts

• Sensory is a science that uses people’s senses to measure food properties

• If proper care (controls) are taken, data can be analyzed statistically to make decisions

• Instruments can also be used to measure properties– …but sensitivity can differ

Review of Concepts

Test types

• Difference tests

– Triangle test

• Attribute tests

• Descriptive test

• Consumer test

Triangle test

• Compare two treatments

• Three samples

– Two equal, one odd

• Count correct responses

• Use table to analyze data

THE FIVE TASTES

The Five Tastes

Umami

The Five Tastes

• Taste buds are the tongue receptors– They regenerate constantly

• Taste sensitivity is lost with age– Kids are specially sensitive to sweets– As we age, sensitivity decreases

• Specially for sweet and salty• Thus, we can enjoy bitter and sour foods

– Or increase seasoning/sugar content

The Five Tastes

• Taste detection depends on concentration of chemical stimulant– Bitter– Sour– Umami– Salty– Sweet

…but there are interactions between the tastes that affect the perceived intensity of each other.

The Five Tastes

• There is also a time-intensity relationship characteristic of chemical stimulants– Food modifiers (e.g., gelatin, maltodextrin, MSG)

can be used to alter it

The Five Tastes

• Stereochemistry– There must be a match between the chemical and

taste receptor– Receptors saturate

• Perception lost due to saturation• Saturation avoided by cleaning frequently

– Water– Soda crackers (unsalted)

The Five Tastes

• Perception affected by– Temperature– Viscosity– Consumption rate– Contact duration– Area of contact– Chemical state of saliva– Presence of other stimulant chemicals

WHAT IS FLAVOR?The five tastes

What is Flavor?

• Flavor is the integrated perception resulting from stimulating– Taste buds – Olfactory receptor– Trigeminal nerve in the palate, throat and cheeks

+ +

Smell - Nose Receptors

• Aromas are the result from the interaction of volatile chemicals with nose receptors– Not all volatiles can be perceived by humans, but in

order to smell it, it has to be volatile• Aromas are affected by

– Structural modifications– Heat– volatilization

Smell - Nose Receptors

• Nose receptors– Saturate – Adapt (get use to the aroma)– “Are emotional”– Are highly sensitive (better than any instrument)– Discriminate about 10,000 different volatiles

• But can identify around 200

Trigeminal Nerve

http://dictionary.reference.com/browse/trigeminal

Also called trigeminal nerve. Either one of the five pairs of cranial nerves, consisting of motor fibers that innervate the muscles of mastication, and of sensory fibers that conduct impulses from the head and face to the brain.

Trigeminal Nerve

• Responsible for sensations from irritant chemicals– Carbonation– Burning – Cooling– Warm/Hot– Pungency– Astringency

Trigeminal Nerve

• Trigeminal sensations are difficult to separate from the taste/aroma perceptions– These are expected in certain products

• Implications to sensory panels and consumer acceptance of products

– Perception of taste/aroma can be affected by trigeminal factors

– Can affect time-intensity perception curves of taste/aroma compounds

REDISCOVERING FLAVOR

The five tastesWhat is flavor?

Rediscovering Flavor

4

Score Card

Scale #1 Notsweet

Extremely sweet

Scale #2 Notsweet

Extremely sweet

Scale #3 Notsweet

Extremely sweet

Scale #4 NotAcid

Extremely Acid

Exercise 2: Relating Perception to Instrumental Data

VS.

Exercise 2: Relating Perception to Instrumental Data

• Pick your product– Orange juice– Apple juice– Tomato Ketchup– Grape jelly– Vanilla yogurt

• Conduct test• Analyze data and prepare graphs

Exercise 2: Relating Perception to Instrumental Data

• Product tested

• Brand rating

• Graphs

– Sweetness

– Acidity

Summary

• Flavor = Taste + Aroma + Trigeminal Sensations– Combination of three senses

• Taste Sweet, Salty, Sour, Bitter, Umami• Aroma Volatile compounds• Trigeminal factors affect acceptance

Questions?

Day 3 ends here…

DAY 4

Rating testsFood textureStudent experiments

Review of Concepts

• Sensory is a science that uses people’s senses to measure food properties

• If proper care (controls) are taken, data can be analyzed statistically to make decisions

• Instruments can also be used to measure properties– …but sensitivity can differ

Review of Concepts

Test types

• Difference tests

– Triangle test

• Attribute tests

• Descriptive test

• Consumer test

Triangle test

• Compare two treatments

• Three samples

– Two equal, one odd

• Count correct responses

• Use table to analyze data

Review of Concepts

• Flavor– Interaction between taste,

aroma and trigeminal nerve sensations

– It can be useful to establish relationships between sensory and instrumental data

RATING TESTS

Attribute Difference Test

• Determine degree of difference between two or more treatments on a specific attribute– Training might be required to ensure panelists

understand the attribute to be evaluated– Training is required if more than one attribute will

be evaluated

Attribute Difference Test

• Test types:

– Directional difference

– Paired ranking

– Simple ranking

– Rating

Rating Tests

• Determine the intensity of an attribute on several treatments at the same time– Three or more treatments

• No less than 10 panelists– Trained to identify attribute

• Data collected on scales– Line– Category

Scales

• Line Scale

• Category Scale

Scale #1 Notsweet

Extremely sweet

Data Analysis

• Prepare data table

• Analyze using ANOVA– In Excel, use “ANOVA two

factors without replication”

Panelist A B C D E

1 2 3 1 5 3

2 0 1 0 2 2

3 0 2 0 2 0

4 3 4 2 5 5

… … … … … …

… … … … … …

17 2 4 3 3 1

18 2 3 3 4 3

19 0 1 0 0 2

20 6 4 3 4 3

Data Analysis

ANOVA

Source of Variation SS df MS F P-value F crit

Rows 128.51 19 6.764 4.998 0.000 1.725

Columns 57.56 4 14.390 10.634 0.000 2.492

Error 102.84 76 1.353

Total 288.91 99        

<- Panelists

<- Treatments

F > F crit, reject “No difference”

P-value < α, reject “No difference”

“No difference” on the Rows (panelist) is not desired. This can be corrected by training or replication of the experiment.

Data Analysis

• If ANOVA yields a “reject no difference” verdict– At least one treatment is significantly different

FOOD TEXTURERating tests

Food Texture

• Food texture refers to the way we perceive food through the senses of touch

• Provide info such as hardness, cohesiveness, sponginess, gumminess, adhesiveness, firmness, etc.

Food Texture

Texture Profile Analysis

Food Texture

Food Texture

Attribute Description

Firmness Slope to maximum force of first cycle

Hardness 1 Maximum force of first cycle

Cohesiveness Ratio of Area 2 to Area 1

Adhesiveness Minimum force (negative) of first cycle

Sponginess Ratio of Hardness 2 to Hardness 1

STUDENT EXPERIMENTS

Rating testsFood texture

DEMO 5: Texture Profile Analysis

Exercise 3: Rating Test on Texture

• Select your project1. Firmness of chocolate ganage2. Softness of scrambled eggs3. Cohesiveness of cookies4. Adhesiveness of rice crisps treats5. Sponginess of cup cakes

• Prepare and execute rating test• Analyze data

Exercise 3: Rating Test on Texture

• Test Objective

• Treatments

• Panel results

• Instrumental data

• Conclusion

Final Words

• Sensory is a science that uses people’s senses to measure food properties

• Measuring food properties can be misleading if proper controls are ignored

• Not just eat your food, enjoy it!– There is much more to it than just nourishment– Let the inner kid out to play (with food) !!!

Questions?

Workshop ends here…