Name: Mechelle Ann F. Lamata
Date performed: Dec. 7, 2011
Group name: Group name
Date submitted: Dec. 14, 2011
FST 150 Sensory Evaluation Evaluation of Food Products Exercise 3. Taste Threshold (Paired Test Method)
Introduction
Taste threshold is the concentration range existing below which the taste of a substance will not be detectable under any practical circumstance, and above which individuals with a normal sense of taste would readily detect the presence of the substance (Lawless and Heymann, 2010). In the paired test method, absolute threshold is being measured. This kind of threshold is defined as the lowest concentration level of a chemical stimulus that is perceivable. This quantitative value varies because it relies on the perception of the t he panelists. It is essential to know this kind of threshold in order to use as reference for the further laboratory exercises. Paired comparison test for simple difference where two coded samples are presented to the t he panelists for evaluation on simple difference There were five pairs of samples presented to each panelist, for each pair, one is water and the other is the sugar solution. The panelist must encircle the sample which contained the stimulus. The sugar solution has different molarities. The main goal of this exper iment is to identify the minimum detectable concentration of sweetness. The specific objectives are: 1) To be able to dete rmine the taste threshold for sweetness using the paired t est method 2) To become familiar with the set- up of a paired test
Materials Cups for the sample Spitting cups Drinking water Tray Masking tape Pentel pen
Sucrose stock solution- Molarity (0.0004, 0.0008, 0.0016, 0.0032, 0.0064)mol/L
Method
The desired amount of the samples for the five various molarities (stated above) for 13 panelists were prepared.
Samples were served in pair with water. The order of serving each pair and within the pair of the samples were randomized .
The scoresheets were evaluated, decoded and recrded on the master sheet. the threshold for sweetness of the class using regression calculation.
A tray for each panelist containingfive pairs of samples was served.
Results
Table 1. Sucrose solution samples and the responses of the panelists Judge
A
X
B
X
C
X
D
X
E
X
1
127
496
x
987
323
X
397
266
/
657
621
/
382
757
/
2
514
398
/
252
748
/
266
179
/
967
221
/
755
875
/
3
778
414
x
237
596
/
974
885
/
852
654
/
119
612
/
4
764
197
/
639
272
/
336
645
/
897
109
/
165
465
/
5
853
531
X
119
112
X
176
356
/
815
941
/
327
478
/
6
451
587
/
911
575
/
689
219
/
227
736
/
713
932
/
7
516
965
X
738
151
X
739
135
/
419
835
/
623
593
/
8
386
930
/
809
408
/
151
405
/
671
328
/
727
301
/
9
194
972
/
525
885
/
542
721
/
246
551
/
654
297
/
10
166
825
/
536
211
X
546
952
/
233
225
/
862
487
/
11
763
498
X
349
941
/
856
127
/
718
137
/
999
592
/
12
428
951
/
737
142
/
536
953
/
745
374
/
814
967
/
13
359
553
Total
/ 8
814
185
/ 9
459
156
/
773
213
13
/
142
441
13
/ 13
Legend: A – 0.0004 mol/L B – 0.0008 mol/L C – 0.0016 mol/L D – 0.0032 mol/L E – 0.0064 mol/L X – water
18 s 16 e s n 14 o p s e 12 R t c 10 e r r o 8 C f o 6 r e b 4 m u N 2
0 0.0004 mol/L 0.0008 mol/L 0.0016 mol/L 0.0032 mol/L 0.0064 mol/L Concentration mol/L
Figure 1. Sucrose solution concentration (mol/ L) versus t he number of correct responses
As the least concentrated sucrose solution (0.0004 mol/L), sample A got the lowest number of correct determination of sweetness. Eight o ut of 13 panelists had correct detect ion of which sample contained sucrose. Nine panelists correctly identified the sucrose Sample B, with the concentration of 0.0008 mol/L. For the samples C, D and E, the panelists were able to identify all the sucrose solution samples. The threshold of the class for sweetness w as calculated using regression calculation (See appendix). The sucrose concentration is the independent variable (x) while the number of correct responses is the dependent variable (y). These variables are analyzed and the slope is 2,396.84, yintercept is 2.02, y1 is 2.98, y2 is 17.36. The regression line or line of best fit is made up of two points y1
and y2. The
intersection between the graph (Fig.1) and the regression line is point (0.0032, 13), the x-
value represents the absolute threshold.
Conclusion
Sucrose solutions of lower concentrations are more difficult to distinguish than those of higher concentrations.
References nd
Lawless, H.T., Heymann, H. Sensory Evaluation of Food, Principles and Practices. 2 Ed. 2010. Springer. New York, London. p. 127
