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SENSORY PANEL METHODS

I. INTRODUCTION A. What is Sensory Evaluation? • Scientific discipline through which the sensory analyst evokes, measures,

analyzes and interprets human responses to stimuli as perceived through the senses.

B. How is Sensory Evaluation used?

1. Acceptable versus unacceptable

2. Determine differences in meat products due to production and/or

processing II. TYPES OF PANELS A. Affective - consumer panels

• Untrained

• Determine acceptable versus unacceptable B. Analytical - trained panels

• Used in research or product development

• Determine intensity of characteristics III. SELECTION OF PANEL TYPE

• Dependent on goals and nature of the product

A. Basic research

1. Analytical

2. Affective

B. New product development

1. Bench top

2. Analytical

3. Affective

C. Product optimization

1. Analytical

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D. QA/QC

1. Analytical • Each panel has its own specific goals and degree of training requirements IV. AFFECTIVE PANELS

A. Measures consumer reactions to a particular product in terms of:

1. Acceptance/preference - 9 point hedonic scale

2. Difference/degree of difference between samples

B. Definition of population of interest

1. Who buys/consumes it

2. Limitations of population

3. Design questionnaire accordingly

C. Random sample

D. 50 to 100 (75 to 100)

E. Types of questionnaires:

1. Facial hedonic

2. Intensity scale

V. ANALYTICAL PANELS

A. Panelists function as human instruments in evaluating his/her objective impression of an attribute.

• Never ask a trained panelist to give a consumer response

• Select people with normal acuity

B. Panel consists of a group of subjects who have been carefully screened, selected, trained and verified to objectively evaluate the test samples.

Selecting - Review Cross et al., 1978 on "Training and Testing of Judges of Sensory Analysis of Meat Quality."

1. Prescreening interview - 3 to 4 times more than need

a. Interest - essential

• Expectations - time, pay, social contact, commitment

b. Availability - essential

• Travel, family, other commitments

c. Health

• Generally good

• Allergies, especially to the food (s) you are testing

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• Colds/sinus problems - decreased acuity, increased absences

• High blood pressure - salty products

• Diabetes - sweet products

• Dentures

d. Attitude/motivation

e. Inform candidates of: • Demands of time

• Commitment requirements

• Value to your program

2. Screening - twise as many as needed - 50% dropout rate

• Scaling exercises

• Ability to distinguish or describe differences in product(s) to be tested

a. Triangle tests - decision on good or bad

(1) Accept as a potential panelist

(2) Reject

(3) Continue testing

b. Sniff tests

• Never accept an inferior candidate just to meet number requirements.

3. Training

a. Purpose:

(1) Familiarize the individual with test procedures

(2) Improve the individual's ability to recognize and identify sensory attributes

(3) Improve the individual's sensitivity to and memory for test attributes, so that sensory judgements will be precise and consistent

b. Procedures:

(1) Select and train extra panelists because approximately 20% drop out rate during initial phases of training, additional 20% drop out rate from then on due to: loss of interest, relocation, mortality

(2) Instruction of techniques

• Spit versus swallow

• Rinsing

• Methods of evaluation

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• Scales

• Score sheet

• Terminology or lexicon

(3) Present references for each attribute tested

(4) Concentrate on one attribute each session till familiar with that attribute

(5) Present anchor points on the scale for each attribute

(6) Panelists score samples individually, discuss results as a group, panel leader determines scores for each sample

(7) Train until consistent results obtained between panelists and by each panelist

3. Verification/Performance evaluation

a. Purpose:

(1) Identify problems among individual panelists

(2) Identify areas for further training requirements for entire panel

b. Procedures:

(1) Samples evaluated in several sessions over several days, ie. Spread over 4 days with 3 sessions per day and 3 samples per session

(2) To determine consistency over time

• to determine ability to discriminate among samples

• the larger the F-ratio, the better the panelist

(3) Retrain and reevaluate as needed

C. Five to twelve panelists

D. Degree/length of training depends on:

1. Type of panel

2. Number of attributes

3. Previous panel experience

VI. CLASSIFICATION OF ANALYTICAL PANELS

A. Discriminative

1. Difference/Similarity

a. Paired comparison (are they different or the same)

b. Duo-trio (which one is similar to the control-2 chances)

c. Triangle (which one is different - 3 chances)

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d. Rating-difference (scalar difference from control)

2. Sensitivity a. Threshold

b. Dilution

B. Descriptive

1. Single sample (monodic) - present one sample at a time

2. Ranking -

3. Quality rating (scalar scoring) -

4. Magnitude estimation - based on assignment of a number for the first sample tested, after which all subsequent numbers for the subsequent samples are assigned in proportion.

5. Texture profile - the analysis of a product's perceived manifestation of the structure or inner make-up of foods in terms of: fell (tactile) and resistance to applied forces (kinesthetic).

6. Quantitative descriptive analysis - relies heavily on statistical analysis to determine the appropriate terms, procedures, and panelists to be used for analysis of a specific product.

• Training requires the use of product and ingredient references to stimulate the generation of terminology.

• Evaluated on computer. Reported in "spider web" with a branch or spoke for each attribute

7. Flavor profile - the analysis of a product's perceived aroma and flavor characteristics, their intensities, order of appearance, and aftertaste.

• An amplitude rating is generally included as part of the profile

VII. SPECIFIC TYPES OF ANALYTICAL PANELS

A. The flavor profile method (Arthur D. Little, Inc., 1940's)

1. Components

a. Character notes

(1) Cooked beef lean

(2) Cooked beef fat

(3) Browned

(4) Serum/bloody

(5) Grainy/cowy

(6) Cardboard

(7) Painty

(8) Fishy

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(9) Liver/organy

b. Intensity - category scale, 15 point

• 2= soda in saltines

• 5= apple in Mott's apple sauce

• 7 = orange in Minute Maid frozen

• 10= grape in Welch's grape juice

• 12 = cinnamon in Big Red gum

c. Order of appearance

d. Aftertaste

e. Amplitude

2. Selection and training a. Employees of company or institution

b. 30 screened - 10 selected

c. Screened for ability to taste and smell, personality and interest

d. Train 1 year, multiproduct

3. Approach

a. 5 to 6 judges

b. Frame of reference for several products and raw materials

c. Independently evaluate each sample one at a time

d. Discuss results till agreement

4. Results

a. Data no statistically treated

b. Tabular presentation

c. Graphic presentation

B. Texture profile method

1. Components

a. Characteristics - parameters

(1) Feel - use of tactile nerves on surface soft tissues in mouth

(a) Geometrical properties - chalky, gritty, fibrous, grainy

(b) Fat and moisture - greasy, juicy, oily

(2) Resistance to forces:

(a) Hardness

(b) Chewiness

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(c) Viscosity

(d) Cohesiveness

(e) Springiness

(f) Fracturability

(g) Adhesiveness

b. Intensity

c. Order of appearance

d. Other factors

2. Selection and training

a. Full set of teeth

b. Ability to discriminate within texture parameters

c. 10 preselected panelists, oriented with different product types

3. Approach

a. Review large number of samples in each product category

b. Panel develops ballot

c. No taste bud fatigue, can evaluate larger number of samples per session

4. Results

a. Data statistically analyzed (ANOVA)

b. Tabular or graphic

C. The Qualitative Descriptive Analysis (QDA) Method (Stanford Research Institute, 1984, available through Tragon Corp.)

1. Components

a. Characteristics

b. Intensity (6-in unstructured scale)

c. Order predetermined

d. Overall flavor intensity

2. Selection and training a. Screen 2-3x number needed for training

b. Taste acuity using series of triangle tests

c. Interest, availability, personality and health

d. 10 or more judges develop terminology

e. Evaluate samples after 10 or more hours

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3. Approach

a. Only one product type for each panel

b. 10-15 panelists evaluate coded randomized samples

c. 4-6 replicates per sample

d. Data transformed (0-60)

4. Results

a. Statistical analysis (ANOVA)

(1) Performance of each panelist

(2) Treatment differences

b. Graphic

VIII. CONDUCTING THE TEST

A. Testing area

1. Distractions

2. Panel communication

3. Comfort

4. Foreign odors

B. Lighting

C. Testing schedule

1. Time of day

2. Number of samples

D. Sample preparation

1. Preliminary testing - appropriate method of preparation

2. Dilution and carriers

3. Serving temperature

4. Utensils

5. Quantity of sample

6. Number of samples

7. Coding and order of presentation

8. Rinsing

9. Information about samples

E. Factors influencing sensory measurements

1. Expectation error

2. Stimulus error

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3. Logical error

4. Halo effect

5. Suggestion

6. Motivation

7. Contrast effect 8. Positional bias

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