Human panels can be used for color, flavor, juiciness, appearance, texture, rancidity --- just about anything

1. Human panels can be used for color, flavor, juiciness, appearance, texture, rancidity --- just about anything • But the results must be used with caution panels have great potential --- but can easily mislead as well because of human variables

2. Options in sensory panel analyses 1. “trained” - • relatively small (10 - 20 people) panel and trained specifically for characteristics to be evaluated 2. consumer • must be large (100+) because it is highly variable • must be simple --- ask for preferences or differences only --- not a scaled value i.e. “3” on a 5 point scale for color

3. General guidelines for panels 1. sample selection – representative 2. sample handling • cooking, serving temperature, appearance, sanitation, safety 3. selection of panelists • screen for color-blindness, sensitivity to specific flavors, age, sex, dietary life styles, bias about the product, reduce “test” mentality

4. General guidelines for panels 4. lighting - controlled as appropriate for test, mask color for flavor evaluation 5. isolation • booths without interaction with others 6. standards/clearing agents • a reference sample can be useful i.e. Oscar Mayer hot dog • pictures for color comparison • water, fruit juice, unsalted crackers should be provided to return taste buds to a starting point

5. General guidelines for panels 7. sample codes • use 3 digit random numbers • bias for A,B,C, D sequence 8. limit samples to ~ 9 maximum at any one time 9. use an appropriate scale • numbers in the middle of a numerical sequence are less different than those on the ends

6. Scales – Many types of scales or scoring systems -may be structured word scales or graphics. -structured scale of 7 to 10 points is recommended because panelists will avoid using the end points on the scale. -fewer than 7 points scale may not allow the panelists to show the degree of variation observed. Hedonic scale The word " hedonic" is of Greek origin and relates to degree or magnitudes of like or dislike.  

7. Rank preference -rank samples in order of preference -more than 4 or 5 samples in a ranking test creates difficulty for the panelists to rank products More re-testing is generally done in order to assure the correct positioning of the rankings.

8. 10. randomize order of samples evaluated • a large difference between two samples will be given a larger differential in score if one immediately follows the other than if there are others between them

9. Method concepts used for sensory evaluations by taste panels • Preference -most often done with large, untrained consumer panels b) Discrimination -determines how products perceived and significance of difference. it requires trained panel example – uses triangle tests, paired comparison, ranking or scale scoring

10. 1. Triangle test -panelists receive three coded samples, two of the samples are the same and that one is different (chance = 33%) -panelists identify the odd sample - often used as a tool in quality assurance programs to insure that samples from different production lots are not different - also used in product development studies to check effect of ingredient substitutions or changes in processes

11. 2. Duo- Trio test -three samples are presented : one sample is labeled "R"(reference) and the other two are coded. One of the coded samples is identical to "R" and the other coded sample is different. -panelists identify the sample that is same or different from the reference (chance = 50%) -both Triangle and Duo-Trio may be used to screen panelists for their ability to repeatably select a specific trait when tasting products for flavor, the Duo-Trio test is often used instead of the Triangle test because the Duo-Trio requires less tasting.

12. 3. Pairedcomparison test -a pair of coded samples is presented for comparison on the basis of some specified characteristic (saltiness, sweetness etc.) -similar to the triangle tests but fewer samples are required and there is less tasting. The statistical value is not as strong with the paired comparison as it is with triangle test (chance = 50%)

13. 4. Ranking test -an extension of paired- comparison tests. -panelists receive three or more coded samples and are asked to rank samples for intensity of some specific characteristic. -often used to screen one or two "best samples' from a group of samples rather than to thoroughly test all samples. -no indication of the magnitude of difference between samples is obtained because samples are only evaluated in relationship to each other.

14. 5. Scale scoring (descriptive, structured) -Hedonic scale, usually 9 points 9-extremely desireable 8-very 7-moderately 6-slightly 5-neither nor 4-slightly undesireable 3-moderately 2-very 1-extremely

15. Line scales (unstructured) Flavor: extremely extremely desireable undesireable

16. c) Descriptive methods -discrimination of qualitative and quantitative traits of a sample by use of a small ( 5- 10) member, very highly trained panel -highly sophisticated, analytical approach -techniques such as flavor profile, textural profile and QDA ( quantitative descriptive analysis) are used. -requires at least three evaluative processes; 1. discrimination of the trait ; 2. description of the trait; and 3. quantifying the trait.

17. The steps of discrimination and description of traits are qualitative. -language used is developed through careful training and practice with the panel. -panelists develop a common vocabulary for various sensory stimuli with descriptive language. The third step in descriptive analysis is to quantify the traits as to how strong they are, and sometimes the order of detection, i.e. flavor profile (Arthur D. Little Co.) -provides a total picture or profile of a food product -may be used to suggest instrumental methods or more commonly as a method of quality assurance or quality control.

19. Review laboratory manual pp.82-87 for a variety of forms that can be used in our lab. A structured (numerical) scale (p.82 and p. 86) or a unstructured line scale (p. 87) would probably work best for most 460/560 products. -you select the characteristics to be scored for your product. Prepare and bring score sheet to lab. to use

20. Texture measurements Options: • Human panels -same considerations for panel selection, sample preparation, sample evaluation, etc. as for flavor and color -latest development in textural analyses with sensory panels is coordinating sound (crunch, crackle, snap, etc.) with textural assessment

21. 2. Texture instruments a. Instron – used a great deal in many industries, previously used for food but less common now b. Texture Analyser-TA XT2i (Meat Lab.) c. instruments allow several texture measures including texture profile analysis (TPA)

22. Texture Analyser

23. Texture measurements • Compression (tomatoes, strawberries, etc. -force without rupture) • Penetration/puncture (sausage skin “snap”) • Shear (resistance to cutting, toughness) • Extrusion (resistance to flow or pumping) • Tension (stretch, i.e., rubber band or stretch to break, i.e., restructured ham) • Breaking/bending (bone strength) • Texture profile analysis (TPA)

24. Compression test

25. Warner-Bratzler shear test

26. Tension measurement

27. Texture Profile Analysis (TPA) • TPA uses compression, release, recompression and re-release, often called the “two bite” test. • Provides several different textural properties • Correlates very well with sensory panel evaluations.

28. TPA results

29. Hardness or Firmness = maximum force of first compression (height of first peak)

30. Cohesiveness = area under peak 2/area under peak 1 Gumminess = Hardness X Cohesiveness Springiness = height of sample recovery in the second compression Adhesiveness = maximum negative force after 1st compression