Sensory Evaluation Method - Assignment Example

Sensory Evaluation Analytical sensory tests are the sensory evaluation methods that require analysis in getting information regarding a s reaction to differences between samples. Among the analytical type of tests are the single sample, two sample or paired, triangle, duo-trio and the multi-sample scoring and scaling. These methods are the bases upon which other approaches and variations are developed. Each test has its own specific uses and limitations. The extent of their usefulness may be determined mainly by the type of information desired, the number of test samples and the available time, effort and money. (Gatchalian , 1975) Difference - The easiest to conduct and analyze. The method involves the presentation of a set of samples one at a time, in equally spaced intervals. Only one stimulus is being evaluated at any one time. A single sample is presented at a time but evaluation is passed on several samples which are successfully presented. Evaluation is based largely on pre-established "memory standards".(Pangborn, 1967) The first sample to be evaluated, coded "A" is the standard. The preceding samples will be identified whether it is same as sample coded "A" or "Not A" while memory is relied upon acquaintance with the "standard" would reduce the wide time elapsed needed for recall. This method can be used by expert tasters or consumers for product acceptance tests. This test is utilized in conditions where products of heterogeneous properties are to be compared for one homogeneous quality, e.g. products are different in all aspects except flaws. This test is used for product development, product comparison and storage stability. Paired or Two-Sample Test Method - Two samples are presented at any one point for evaluation. Samples in pairs presented successively for evaluation. The panelists are asked if they find a "difference" or "no difference" between the pair of samples presented. Analysis of the results will establish if a difference exists between samples. If there is a difference, further tests could be done to establish the extent of the difference. This test can be used in the panel selection and in regular monitoring of the panel sensitivity. This test is used for product development and evaluation and product comparison. This test can also be used in the determination of the threshold difference. Duo-Trio Test - This method is a modification of the two sample and triangle tests, or a combination of single sample and paired comparison tests. Three samples are used, two of which are alike as in the triangle test. However, in this test, the control/reference sample is made known to the panelist and he is then asked to pick the sample similar to the control/reference. This test is used for difference tests needed in quality control to determine variations between batches of production; stored and fresh products and for product improvement and development studies. The Triangle Test - This method utilizes three samples at any one time with two of the samples being identical and the third different. The latter is the unknown. This test is used mainly for product development and improvement and quality control. This is used in storage studies and product improvement activities. This test can also be used for panel selection and training purposes and in instrument correlation. Category or Descriptive Sensory Test Hedonic Scale method is a measure of acceptability gauged from consumer reaction in terms of their degree of like or dislike for a given product under a given set of conditions. The evaluators' reactions are indicated by descriptive words on a scale. This test is used to detect small differences in the degree of liking for similar foods and to detect gross differences even when time, subject and test conditions are allowed to vary. (Amerine, et. al., 1965) Ranking for Preference or Consumer-Type Test - In this method, different samples are usually presented for preference judgment to untrained panels. This test is used to aid product developers in pinpointing product formulations for consumer testing. This allows for top-ranking products to be selected for final consumer tests. Preference is relative and does not necessarily indicate acceptability. Acceptance tests - Specific method used to establish a product's level of acceptability. Experimental Section 1. Difference Test - Hand Creams - In this test, there will be 4 coded samples presented to 12 panelists. For the first set, sample # 1 will be used as the control and will be the first to be presented to the panel for testing. Sample # 1 will be taken back and replaced with sample #2. Panelist will compare Sample #2 with Sample #1 and evaluate if they are the same product. Sample #2 will be replaced with Sample #3 and then again compared with Sample #1. Sample #3 will then be replaced with Sample #4 and then compared again with Sample #1. The next round will have Sample #2 as the control and the same process will be done again. The same process will again be repeated until all the samples have been used as control samples. 2. Paired Test - Hand Creams - In this test, there will be 4 coded sample presented to the 12 panelists. In every set, 2 samples will be presented to each panelist for comparison if there is a difference. Since there are 4 samples, each panelist will have to compare six sets of the combination of the 4 samples. 3. Triangle Test -Hand Creams - In this test, three coded samples will be presented per set, two of which are the same. Each panelist will evaluate which is the odd sample In this case, 12 sets of combination of coded samples will be presented to the panel. 4. Duo-Trio Test -Hand Creams - The preparation and presentation of the coded samples is the same as the triangle test. The only difference is that in the latter, the control sample is known and the panelist is asked to choose which of the two remaining samples is the same as the control sample. 5. Ranking Test - Biscuits -A set of four coded samples of biscuits will be presented to the 20 panelists. Each panelist will evaluate the biscuits on the following attributes: appearance, aroma, taste, and texture. The panelist will rank each sample based on his degree of preference with the most liked sample getting the highest numerical ranking. 6. Category / Hedonics - Cheeses / Lip Salve - For cheeses, a set of four coded samples of cheeses will be presented to the 24 panelists for evaluation. The panelist will evaluate the cheeses on the following attributes: appearance and taste. The panelist will use the descriptor words with corresponding "values" (numbers) in the scale parameters in evaluating the samples. For the lip salve, a set of coded samples of lip salve will be presented to the 12 panelists for evaluation. The following attributes will be evaluated: appearance, softness, feel, smell. The same procedure used in evaluation of cheeses will be used. Results Type of Test # of Trials # of Correct ID Significance* Difference Test 48 28 NSD Paired Test 72 40 NSD Triangle Test 48 26 NSD Duo-Trio Test 48 14 NSD *Taken from : Roessler, E.B., R.M. Pangborn, J.L., Sidel and H. Stone, 1978. Expanded statistical tables for estimating significance in paired preference, paired-difference, duo-trio and triangle tests. Journal of Food Science. Vol. 43, p. 940-943. Copyright, JFS NSD - No Significant Difference Ranking Test - Biscuits : No. of Samples : 4 Number of Panelists Attribute Evaluated Significance at 10 %, 5% and 1% Levels* Tukey's HSD at 5% Significance Level** 20 Appearance NSD at 10%, 5%, 1% NSD 20 Aroma NSD at 10%, 5%, 1% NSD 20 Taste NSD at 10%, 5%, 1% NSD 20 Texture NSD at 10%, 5%, 1% NSD *Taken from Amerine, et, al, 1965. Values of Chi-Square required for significance at various levels. ** Abridged from: Kramer, Amihud, "A Rapid Method for Determining Significance of Differences from Rank Sums," Food Technology, Vol. 14, 1960, pp. 576-581. Copyright 1960 by the Institute of Food Technologists. Category / Hedonics- Cheeses : No. of Samples : 4 Number of Panelists Attribute Evaluated ANOVA Significant Factors Tukey's HSD at 5% Significance Level** 24 Appearance Samples - NSD Panelists - Significant NSD 24 Taste Samples - NSD Panelists - Significant NSD Category / Hedonics - Lip Salve : No. of Samples : 4 Number of Panelists Attribute Evaluated ANOVA Significant Factors*** Tukey's HSD at 5% Significance Level 12 Appearance Samples - NSD NSD 12 Softness Samples - Significant Panelists - Significant Sample #3 significantly different from others 12 Feel Samples - NSD Panelists - Significant NSD 12 Smell Samples - Significant Panelists - Significant NSD *** Adapted with permission from Biometrics Tables for Statisticians, 2nd ed., Vol.1, Pearson, E. S. and Hartley, H.O., eds., Copyright 1958 Discussion of Results 1. Hand Cream Tests - Results for all the tests conducted showed that there is no significant difference noted by the panelists on the 4 samples when evaluated. 2. Biscuits Tests - The final results were based on the cross tabulated results of the rankings of the panelists against the samples. With the use of the Chi-Square Analysis, the Calculated Friedma Statistic was derived at and compared with the values from the chi square table of values required for significance at certain levels. If the calculated values are lower than the values from the table, then there is no significant difference in the rankings of the samples. Based also on the ranks sums table, there is no significant difference in the rankings of the samples. The results showed that there is no significant difference in the preference of the panelists among the samples. 3. Cheeses / Lip Salve Tests - For these two products, the ANOVA or analysis of Variance is used to determine the factors that affected the final results. The ANOVA results can specify the variances that need to be controlled for the next tests. Category / Hedonics test is an acceptance test based on the scale parameters that the panelists have to choose from. The descriptor words range from dislike extremely to like extremely with numerical values from 1 to 9 correspondingly. In the cheeses test, the panelists' perception of the appearance is a significant factor in the rankings of the samples while for the taste attribute, both the samples and the panelists had no significant contribution in the variances. In the lip salve tests, it is only in the appearance and feel that the samples have no significant effect on the variance while for the softness and smell, the samples have significant effects on the variance of the rankings. The panelists, however, are significant factors in the rankings of all the attributes. For the sum of ranks analysis, sample #3 ranking is significantly different compared to the other samples. The results of the difference tests and the preference and acceptance tests showed that in the latter test, the human factor greatly affected the final results. This is because the rankings and the preferences are subjective. The samples attributes were ranked based on the perceptions of the panelists. The difference tests were more objective. The panelists only have to decide if there is a difference or none between samples. The above tests were examples to show that application of the suitable sensory evaluation methods is one of the factors that will give us the best results. BIBLIOGRAPHY Amerine, Maynard, R., R.M., Pangborn and E. B. Roessler, 1965, Principles of Sensory Evaluation of Foods, Academic Press, N.Y. Gatchalian, Milflora M. 1975, Sensory Evaluation Methods for Research and Product Development and Quality Control of Foods, U.P., FSN, College of Home Economics, Diliman, Philippines. Pangborn, R. M. 1967, Use and Misuse of Sensory Methodology, Food Quality. 15 pp 7-12. 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