(QDA)

Question 1

QUANTITATIVE DESCRIPTIVE ANALYSIS
(QDA) METHOD

Answer 1

• 10 to 12 panelist are selected according to their ability to distinguish differences in sensory properties among samples.

Question 2

Training for quantitative descriptive analysis testing- The amount of time required for
training program is depend on:

Answer 2

-Complexity of the product
-Number of attributes
-The requirements for validity and reliability results

Question 3

Steps in quantitative descriptive analysis
(QDA)

Answer 3

Terminology generation

Agreement

Determining assessment protocol

Training the panel to rate intensity

Performance check

Data generation

Question 4

1. Terminology generation

Answer 4

• The panelists are exposed to all
  samples, or at least a subset of samples
  that represent the extremes and
  illustrate all attributes.
• Panelists generate terms to describe
  the qualities of sensations present.
• The panelist need to describe a range of
  samples (bread) using own terms.

Question 5

2. Agreement

Answer 5

• Panelists discuss of all selected terms.
• All panelists agree the perceptual meaning of the attributes, attribute name, written definition, method of assessment that illustrates the sensory experience of the attribute.
• Panelists generate a consensus terminology for each sensory attribute.

Question 6

3. Determining assessment protocol

Answer 6

• The assessment protocol should control for bias.
• Some products may require a carrier.
• The assessment protocol should include methods to overcome
  sensory fatigue and adaptation between samples.
• The leader acts as a facilitator by directing discussion and supplying
  reference materials and other samples required by the panelists.

Question 7

4. Training the panel to rate the intensity

Answer 7

• Run training sessions on terms and intensities.
• Once the attributes and assessment protocol have been agreed, the
  product can be evaluated by rating the intensity of each attribute on a
  scale.
• Intensity training can include the following:
  ü Basic training on how to use the scale type.
  ü Training on how to use of the ends of the scale (reference samples).
  ü Calibration across panellists.
  üTraining to improve consistency and reproducibility result.

Question 8

5. Performance check

Answer 8

• A performance check should be carried out to confirm that the panel is performing in a
  consistent and reliable way prior to undertaking
  any studies.

Question 8

6. Data generation

Answer 8

• Samples need to be prepared according to strict protocols and
  presented to assessors according to the experimental design.
• Panelists evaluate the product in isolation booth to reduce the
  distraction and interaction.
• Prior to assessing the experimental samples, a control sample may be
  assessed to remind and calibrate panellists to attribute qualities and
  intensity rating.
• Carry out replicate assessments within a study, duplicate or triplicate
  assessment are most common.