Is this the best way to evaluate products?...

1. Is this the best way to evaluate products?...

2. Describe what is she doing ?

3. Get motivated, familiar and … ?

4. Methods For Sensory Testing Before carrying out sensory testing: • Researcher must be thoroughly familiar with each method – its advantages and disadvantages • Researcher must precisely define his objectives & what information he is expected to collect • With above information, he should select the most practical & efficient method

5. 3 types of sensory tests: • Discriminatory/ Difference tests • Used to determine whether a difference exists between samples • The panelists does not allow his personal likes and dislikes to influence his response/ judgment • Preference/ Acceptance tests • Tests based on a measure of preference or a measure from which relative preference can be determined • The personal feeling of a panelist toward the products directs his response • Descriptive tests • Used to determine the nature & intensity of the differences

6. Interpretation of sensory test results • All sensory experiments must be planned in advance, to make them > efficient • Interpretation of sensory test results cannot be made by direct examination, due to variability of sensory test results • Results must be tested by statistical methods: • These methods compare the results actually obtained with those that would be obtained by chance alone • Results are usually expressed in degrees of significance, which is the probability that the results are caused by chance

7. Types of tests

8. Difference/discriminatory tests • Triangle test • Test is very useful in: • QC work – to ensure samples from different production lots are the same • Ingredient substitution or change in manufacturing – to determine if change results in detectable difference in product • Panelists selection (often used) • Panelists receive 3 coded samples. Two of the samples are the same (i.e.duplicate samples) and one is different (odd sample). The panelist is asked to identify the odd sample • Note: panelist is asked to find/detect any differences

9. Results of a triangle test indicate whether or not there is a detectable difference between two samples • As number of judgments increases, % of correct responses required for significance decreases • Higher level of significance do not indicate that the differences is greater but there is less probability of saying there is a difference when the fact there is none • Eg. Of questionnaire – pg 21 • Analysis of results – pg 22 • Advantages of test: • Researcher receives information on size difference between samples • Researcher also receives information on product acceptance (although results need to be confirmed by a preference test)

10. 2. Simple paired comparison tests • A pair of coded samples is presented to panelists for comparison on the basis of some specific characteristics. Eg. sweetness • Applications are similar to triangle test • Fewer samples are required & there is less tasting (however, statistically test is less efficient, as the probability of selecting a sample by chance is 50% or ½) • Test gives no indication of the size difference between the two samples • Eg. Of questionnaire – pg 23 • Analysis of results – pg 24

11. 3. Multiple paired comparison tests • When there are >2 samples to be evaluated, each must be compared with every other sampler for a single attribute • The number of pairs is determined by the formula: • 1/2n(n-1) where n =no. of samples or treatments • Useful for sets of three to six samples to be evaluated by a relatively inexperienced panel • A panelist is presented with one pair of sample at a time in random order with the question, “ Which sample is sweeter?” • The panelist will be continue to evaluate all possible pairs that can be formed from the samples • Results will be evaluated by a Friedman – type statistical analysis (excluded from syllabus)

12. 4. Duo-trio test • Three (3) samples are presented to panelists; one is labeled as R (reference) & the other two are coded • Panelist has to identify the odd/different sample • Test has the same application as the Triangle test, but is less efficient, as the probability of selecting the correct sample by chance is 50% or ½ • Test is often used instead of triangle test when tasting samples that have a strong flavour because less tasting is required • In this test panelist bases his judgment on any difference he can detect (compare with Paired comparison test) • Eg –questionnaire – pg 30 • Analysis of results – pg 30 -31

13. 5. Multiple comparison test • Test is used to examine the effects of replacing/changing an ingredient, packaging material, process or storage • Panelist is presented with a known reference/standard sample (labeled as R) & together with several coded samples • Panelist has to compare each coded sample with reference sample on the basis of specific characteristics • Test is used very efficiently to evaluate 4 or sample 5 at a time • Small differences between samples &R can be detected • Test gives information about size & direction of difference • Eg of questionnaire – pg 32 • Analysis of results – pg 33 -37

14. 6. Ranking test • Panelists receives 3 or more coded samples and has to rank them for intensity of a specific characteristics • A rapid test and allows testing of several samples at once • Test is generally used to screen one or twoof the best samples from a group of samples • No indication of size of differences between samples • Results from 1 set of rank cannot be compared with the results of another set of ranks • Eg of questionnaire – pg 38 • Analysis of results – • Method I – Comparison of rank totals with rank totals in Chart 5 (pg 38 -39) • Method II – ANOVA (pg 39 -41) – excluded from syllabus

15. 7. Scoring test • Coded samples are evaluated for the intensity of a specific characteristics • Panelists records his judgment on a graduated scale • Intervals on the scale can be labeled with numbers or descriptive terms • For effective results, descriptive terms must be carefully selected • Size & direction of difference between samples can be obtained • Include standards at various points if possible: • To minimise panel variability • To prevent drift in meaning of terms with time • Eg. Of questionnaire – pg 43 • Analysis of results – pg 44 -46

16. PREFERENCE TESTS • Paired comparison test • The test used in preference testing is similar to that used for difference testing • Panelists is presented with 2 coded samples and is asked which he prefers • Eg of questionnaire – pg 56 • Analysis of results – pg 56 2. Hedonic scale • Most commonly used scale for preference testing is the 9-point Hedonic scale • Panelist expresses his degree of liking or disliking for a particular product

17. Other variations of Hedonic scale: • 5-point hedonic scale • Facial expression (9-point or 5-point) • Eg of questionnaire – pg 57 • Analysis of results – pg 58 – 59 • Ranking test • Panelist is presented with coded samples to rank in order of preference • Eg of questionnaire – pg 57 • Analysis of results – pg 58 -59