food evaluation

2. INTRODUCTION
 “Flavor is the sensation produced by a material taken
in the mouth, perceived principally by the sensesof
tasteand smell, and also by the general pain and
temperaturereceptors in the mouth.”
 “ Flavor is one of the three main sensory properties
which are decisive in the selection, acceptance, and
ingestion of a food.”

3. Stimulus Senses Sensory Response
Taste
Food Flavor
Odor

4. CHEMICAL METHODS
 SOLID PHASE EXTRACTION:- Compounds thatare
dissolved orsuspended in a liquid mixtureare
separated from othercompounds in the mixture
according to theirphysical and chemical properties
 SOLID-PHASE MICROEXTRACTION, OR SPME:-
# A sample preparation technique used both in the
laboratoryand on-site
# A very shortgas chromatographycolumn turned
inside out

5. INSTRUMENTAL METHODS
 GAS CHROMATOGRAPHY (GC)
 GAS CHROMATOGRAPHY-MASS SPECTROMETRY (GC-
MS)
 GAS CHROMATOGRAPHY-OLFACTROMETRY (GC-O)

6. GAS CHROMATOGRAPHY
 WIDELY USED ANALYTICAL TECHNIQUE
 EXCELLENT SEPARATION POWERS AND EXTREME
SENSITIVITY
 LOW SAMPLE CAPACITIES
 IMPOSSIBLE TO DEDUCE THE OVERALL SAMPLE
ODOR THRESHOLD
 TWO DIMENSIONAL GC (GC XGC)

8. DETECTORS USED
FID
NPD
ECD
TCD
PID
FPD
PFPD

9. GC-MS

10. GC-O

11. SENSORY TESTS
It involves useof senses (physiological response):
 Olfactoryreceptors
 Taste receptors
 Visual receptors

12. SENSORY TESTING TECHNIQUES
 Preference test - whetherpeople likeordislikea product.
E.g.:



Hedonic scale
Paired comparison tests
Scoring
 Discrimination test - todescribea particularattributeof a
product. e.g.
 Triangle test
 Duo trio test
 Ranking

13. Hedonic scale
 Samples given in a random order
 Testers have to rank in orderof preferenceof a specific
quality ( e.g. Salty taste)
 Minimum of 10 testers required togiveaccurate results

14. Scoring
 Food samplesare scored on a scale, between dislikeand
like.
 Testers are allowed toevaluatesamplesand score.

15. Triangle test
 Consists of THREE samples – 2 IDENTICAL/ 1
DIFFERENT
 Testers need to IDENTIFY the DIFFERENT SAMPLE
 More efficientthan paired comparison

16. Duo trio test
 Consists of THREE samples – 2 IDENTICAL/ 1 DIFFERENT
 Using one of the two identical samplesas a control, testers
are allowed todecidewhich of the other tworemaining
samples is the sameas the control.

17. Ranking test
 Decided on theattribute to be ranked, e.g. crunchiness.
 Testers are allowed toevaluatesamplesand place them in
rank orderaccording to the presenceorabsence of the
attribute from ‘very’ to ‘notatall’
.

18. OTHER TESTS
It includes:
 Threshold test
 Intensityrating test
 Time-intensity test
 Descriptive test
 Consumertest
 Qualitycontrol test

19. ANY QUERIES???