Sensory evaluations tests.

1. Difference-from-
Control test
Method
Quality of
Deli-style Turkey Enriched with
Plant Sterols

3. Sensory evaluation was carried out using a
difference from-control test.
Untrained panellists (32 post graduate students
and staff of the School of Agriculture and Food
Science at University College Dublin) were
recruited.
The sensory analysis was performed on the freshly
cooked and chilled (4 C) turkey slices (2 mm thick).
The difference-from-control test was carried out in
a sensory analysis suite equipped with individual
testing booths and controlled lighting to neutralise
any possible differences in colour or appearance of
the meat.
Panellists were provided with still mineral water to
cleanse the palate between samples.
SENSORY EVALUATION

4. • The difference-from-control test method was used to
detect and quantify the difference between an identified
control/reference sample (C) and a coded sample, which
was either a blind C or S sample
• For the test, each subject was simultaneously given a
sample (C) labelled as ‘control’ plus one test sample
labelled with a random 3-digit code.
• Subjects were told that the test sample might be the
same as control.
• The test was designed such that all subjects assessed
both sample combinations (C-C and C-S) and presentation
order was randomised for each panellist.
DIFFERENCE-FROM-CONTROL TEST

5. • The C-C (blind control) was a duplicate presentation of a
control sample and served as an experimental control for noise. It
represents the degree of heterogeneity in the samples and is also
a measure of the so-called ‘placebo’ effect, which is the
numerical effect of simply asking the ‘difference’ question when
in fact no difference.
• Subjects were initially asked to rate the size of the overall
sensory difference between control and test sample on the
difference scale given, where 0 ¼ no difference, 1 ¼ very small
difference, 2 ¼ small difference, 3 ¼ moderate difference, 4 ¼
large difference, 5 ¼ very large difference and 6 ¼ extreme
difference.
• If no difference was found (0 ¼ no difference), the panellist
reached the end of the test. However, if an overall sensory
difference was detected (between 1 ¼ very small difference and 6
¼ extreme difference), subjects were asked to specifically indicate
the degree of the sensory difference between samples on colour,
texture and flavour using similar difference scales
DIFFERENCE-FROM-CONTROL TEST

6. STATISTICAL
ANALYSIS
• Statistical analysis In order to determine
significant differences (P < 0.05) between C
and S turkey, experimental data of the three
replicates were compared by one-way
analyses of variance (ANOVA) and t tests.
• Two-way ANOVA and Tukey’s tests were
used to determine significant differences (P
< 0.05) among different formulations and
storage times.
• The statistical software used was SPSS
version 20 (SPSS Inc. Chicago, IL, USA).

7. RESULTS AND DISCUSSION
The proximate compositions of C and S cooked turkey samples are presented in Table 2.
 Moisture, protein and ash were significantly different
between the two formulations (P 0.003), while there
was no significant difference in fat content (P ¼
0.400).
 In order to calculate the fat content of the S samples,
from the overall fat value obtained by Soxhlet
analysis, the plant sterol content quantified by gas
chromotography (GC) was subtracted.
 In the S samples, as expected due to the addition of
the plant sterol powder, moisture and protein
contents were lower and ash was higher.
 In both C and S samples, fat and protein content was
comparable with that of commercial deli-style turkey
(around 1–2% fat and 20–24% protein).No difference
in pH between the C and S samples was noted (P ¼
0.909).

8. RESULTS AND DISCUSSION  The results of the difference-from-control test are summarised in
Figure 3.
 S samples were considered significantly different from C in all
parameters considered (overall difference, colour, texture and
flavour) (P 0.0001).
 If the ‘placebo’ effect is removed, and therefore the average S
samples scores minus the average C samples scores are considered,
overall S samples were considered different from C by less than 2
scale units in all parameters considered. This indicates that overall
the panellists considered S samples to be quite similar to C samples.
 In particular, while the overall sensory difference between S and C
samples was considered to be on average 1.8 (close to ‘small
difference’), the specific sensory differences between C and S
samples on colour, texture and flavour were considered 1.4, 1.6 and
1.8, respectively.
 These results show that S and C samples were considered to differ
mostly on flavour (1.8 ¼ close to ‘small difference’), while for texture
and colour the intensity of difference was slightly lower (1.6 and 1.4
are between ‘very small difference’ and ‘small difference’).
 Therefore, the plant sterol addition had an overall effect on the
sensory quality of the product, while specifically the flavour, texture
and colour were affected to a different extent by the plant sterol
addition.

9. THANK YOU FOR
ATTENTION!
ANY QUESTIONS?