Descriptive analysis for sensory evaluation
-
Upload
andrew-myrthong -
Category
Food
-
view
12.080 -
download
2
Transcript of Descriptive analysis for sensory evaluation
![Page 1: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/1.jpg)
1
DESCRIPTIVE ANALYSIS
Andrew L Myrthong2014-12-126
![Page 2: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/2.jpg)
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
![Page 3: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/3.jpg)
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.
![Page 4: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/4.jpg)
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
![Page 5: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/5.jpg)
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
![Page 6: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/6.jpg)
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
![Page 7: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/7.jpg)
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
![Page 8: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/8.jpg)
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
![Page 9: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/9.jpg)
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
![Page 10: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/10.jpg)
10
Training of panellists
• Reference scales are used to ensure consistency between panellists across repeated evaluations
![Page 11: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/11.jpg)
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
![Page 12: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/12.jpg)
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
![Page 13: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/13.jpg)
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
![Page 14: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/14.jpg)
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)
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
![Page 15: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/15.jpg)
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
![Page 16: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/16.jpg)
16
Flavour profile• 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 panelDisadvantages:• Consensus
method means risk of bias from dominant personality
• Danger of lack of consis-
tency and reproducibility
![Page 17: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/17.jpg)
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
![Page 18: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/18.jpg)
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
![Page 19: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/19.jpg)
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
![Page 20: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/20.jpg)
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
![Page 21: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/21.jpg)
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
![Page 22: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/22.jpg)
22
Let Us Sum Up• 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
.
![Page 23: Descriptive analysis for sensory evaluation](https://reader036.fdocuments.in/reader036/viewer/2022062316/58f9b020760da3da068bb40d/html5/thumbnails/23.jpg)
23
Thankyou