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DESCRIPTIVE ANALYSIS
1
Andrew L Myrthong
2014-12-126
Introduction
• Descriptive analysis is concerned with trying to provide
description of the sensory qualities of food
• It ...
Application of descriptive analysis
• The purpose of descriptive analysis is
to obtain detailed description of
– Aroma
– F...
Uses of descriptive analysis include
• Research and Development (long term studies)
• New product development
• Specificat...
Qualitative aspects of descriptive
analysis
• Appearance characteristics
– Colour
– hue, chroma, uniformity, depth
– Surfa...
• Aroma Characteristics
–Olfactory sensations
• vanilla, fruity, floral, skunky
• Nasal feelings
–cool, pungent
• Flavour ...
• Oral texture characteristics
–Mechanical parameters - reaction of product to stress
• hardness, viscosity, deformation/f...
• Skin feel characteristics
–Mechanical parameters - reaction of product to stress
• thickness, ease to spread, slipperine...
Quantitative aspects of descriptive
analysis
• The quantitative aspect or intensity expresses the degree to
which a charac...
Training of panellists
• Reference scales are used to ensure consistency
between panellists across repeated evaluations
10
Types of scale used
• Category scales
• Uses words to define intensity, such as "none", "just detectable",
"mild", "strong...
Overall impression
• As well as rating individual attributes, some kind of "overall
rating" is sometimes needed. These may...
Total intensity of aroma/flavour
• Overal intensity of aroma or flavour is an assessment of the overall
impact the product...
Overall difference
• In some situations, relative difference between samples and controls is
important. This involves a qu...
Common descriptive methods
A variety of procedures have been developed for descriptive testing.
These include
• Flavour pr...
Flavour profile
16
• Uses panel of 4 - 6 trained panellists
• Panel sit round table and evaluate one sample at a time and ...
Texture profile
• Procedure similar to flavour profile, but a
wider range of scaling techniques may be
used
• Results may ...
Quantitative descriptive analysis
• Panelists develop agreed terminology beforehand
• Panelists evaluate products one at a...
Spectrum descriptive analysis
• Panelists score intensities with respect to learned absolute intensity scales
• A wide var...
Time-intensity analysis
• Panelists evaluate intensity of an attribute at intervals over a period
• Time-intensity respons...
Free-choice profiling
• Panelists are allowed to invent their own terms to describe
the sensory attributes of a set of sam...
Let Us Sum Up
22
• The consumer acceptance of fruits/Vegetables and their products most often
relies upon the inherent fla...
Thankyou
23
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Descriptive analysis for sensory evaluation

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Descriptive analysis is an important part of sensory evaluation. It provides information about the qualitative as well as the quantitative evaluation of food and it is widely used for obtaining detailed description about the aroma, flavour and overall texture of the food product

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Descriptive analysis for sensory evaluation

  1. 1. DESCRIPTIVE ANALYSIS 1 Andrew L Myrthong 2014-12-126
  2. 2. Introduction • Descriptive analysis is concerned with trying to provide description of the sensory qualities of food • It is one of three basic types of sensory test: – Difference Tests make comparisons between foods – Affective Tests evaluate liking for foods. These are sometimes called consumer tests – Descriptive Tests describe the sensory attributes of a food 2
  3. 3. Application of descriptive analysis • The purpose of descriptive analysis is to obtain detailed description of – Aroma – Flavour – Oral texture • It is used both to obtain qualitative descriptors of the product and to obtain quantitative evaluations of product. 3
  4. 4. Uses of descriptive analysis include • Research and Development (long term studies) • New product development • Specifications for QA/QC purposes • Define product attributes for consumer tests • Track sensory changes over time • Long term changes for shelf life/packaging studies • Short term intensity measurement of specific attributes • Measure attributes for comparison with instrumental/analytical measurements 4
  5. 5. Qualitative aspects of descriptive analysis • Appearance characteristics – Colour – hue, chroma, uniformity, depth – Surface texture – shine, smoothness/roughness – Size and shape – dimensions, geometry – Interactions among particles – stickiness, agglomeration, loose particles 5
  6. 6. • Aroma Characteristics –Olfactory sensations • vanilla, fruity, floral, skunky • Nasal feelings –cool, pungent • Flavour characteristics – Olfactory sensations • vanilla, fruity, floral, chocolate, skunky, rancid – Taste sensations • salty, sweet, sour, bitter, umami (meatiness) – Oral feeling factors • heat, cool, burn, astringent, metallic 6
  7. 7. • Oral texture characteristics –Mechanical parameters - reaction of product to stress • hardness, viscosity, deformation/fracturability • Geometrical parameters - size, shape, orientation of particles in product –gritty, flaky, grainy, stringy • Fat/moisture parameters - presence/release of fat, oil, water –oily, greasy, juicy, moist 7
  8. 8. • Skin feel characteristics –Mechanical parameters - reaction of product to stress • thickness, ease to spread, slipperiness, denseness –Geometrical parameters - size, shape and orientation of particles • gritty, foamy, flaky –Fat/moisture parameters - presence/release of fat, oil, water • greasy, oily, dry, wet 8
  9. 9. Quantitative aspects of descriptive analysis • The quantitative aspect or intensity expresses the degree to which a characteristic is present and is expressed by assigning a value on a scale • The validity and reliability of the analysis is dependant on the – selection of scaling technique which should encompass full range of intensities – but be sufficiently sensitive to pick up small differences 9
  10. 10. Training of panellists • Reference scales are used to ensure consistency between panellists across repeated evaluations 10
  11. 11. Types of scale used • Category scales • Uses words to define intensity, such as "none", "just detectable", "mild", "strong" • terms chosen to describe (as far as possible) equal intervals - 9 point scale most popular • Line scales: mark a point on a line (typically 15 cm long) • Magnitude estimation (ME) scales • Free choice of first "score" • Subsequent scores assigned in proportion 11
  12. 12. Overall impression • As well as rating individual attributes, some kind of "overall rating" is sometimes needed. These may include – Total intensity of aroma or flavour – Balance/blend – Overall difference – Hedonic ratings 12
  13. 13. Total intensity of aroma/flavour • Overal intensity of aroma or flavour is an assessment of the overall impact the product will have on the consumer Balance/blend (amplitude) • This is an assessment of the way the various flavour or aroma characteristics fit together in the product • It requires highly trained and skilled panel members and is not appropriate with all products 13
  14. 14. Overall difference • In some situations, relative difference between samples and controls is important. This involves a quantifying of the difference from the control (c.f. Duo trio test) 14 Hedonic ratings • This is a rating of the overall acceptance of a product • It is not appropriate with trained panels • Used only with consumer tests since trained panels tend to weigh attributes differently from ordinary consumers and so their judgements are not "typical" of consumer preferences
  15. 15. Common descriptive methods A variety of procedures have been developed for descriptive testing. These include • Flavour profile • Texture profile • Quantitative descriptive analysis (QDA) • Spectrum analysis • Time-Intensity descriptive analysis • Free choice profiling 15
  16. 16. Flavour profile 16 • Uses panel of 4 - 6 trained panellists • Panel sit round table and evaluate one sample at a time and record the ratings • Panel then discusses ratings and arrives at a consensus • Advantage of small panel Disadvantages: • Consensus method means risk of bias from dominant personality • Danger of lack of consis- tency and reproducibility
  17. 17. Texture profile • Procedure similar to flavour profile, but a wider range of scaling techniques may be used • Results may be by consensus method or by statistical analysis • Panel training involves understanding underlying mechanical principles • Experience of a wide range of textural attributes 17
  18. 18. Quantitative descriptive analysis • Panelists develop agreed terminology beforehand • Panelists evaluate products one at a time in separate booths • Panellists are discouraged from discussing results afterwards • Scoring is by marking on a line • The results are analysed statistically • Can lead to inconsistency of results 18
  19. 19. Spectrum descriptive analysis • Panelists score intensities with respect to learned absolute intensity scales • A wide variety of standard descriptors are provided • Scoring is both by use of descriptive terms and by marking on a line • It is intended to provide consistent and reliable data by providing a wide range of standards 19
  20. 20. Time-intensity analysis • Panelists evaluate intensity of an attribute at intervals over a period • Time-intensity response curve is generated • This should not be seen by the panelists while it is being generated • Requires a well-trained panel to be effective 20
  21. 21. Free-choice profiling • Panelists are allowed to invent their own terms to describe the sensory attributes of a set of samples • Samples are from the same category of products • Panelists develop their own scoresheets • These are aimed at identifying terms that appear to measure the same attribute • Panel training requirements are minimal • Panel is closer to a consumer panel 21
  22. 22. Let Us Sum Up 22 • The consumer acceptance of fruits/Vegetables and their products most often relies upon the inherent flavor and textural quality of the product • Incorporating sensory evaluation will help in the selling of a consumer friendly product with increased acceptance • When done properly, sensory information can provide reliable and useful information about fruits and vegetables and their products which no instrument can measure – their perceptual characteristics .
  23. 23. Thankyou 23

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