In deviations with DHS-GC-MS technology. The chocolate samples

                In the
food industry, the characteristics of the product, such as flavor, texture and consistency
of the product all affect to the consumer perception. Therefore, the quality
evaluation of final products plays an important role in chocolate production. Many
techniques have been applied to the food production and be a part of quality
control program to have profile of the final product. Although the modern technology
dynamic headspace sampling (DHS) and gas chromatography with mass spectrometry
(GC-MS) can separate and identify the off-flavor compounds in chocolate, it
cannot account into the consumer perception. Hence, a sensory evaluation is
necessary to analyze the human threshold to detect the volatile compounds in
chocolate which can affect to the product quality. This study was conducted in
a small chocolate company in Denmark. The fast-sensory Rate-All-That-Apply
(RATA) method was applied to this study to compare the effectiveness in capturing
the important sensory deviations with DHS-GC-MS technology.

chocolate samples were produced especially for this study with regular
processing production and some potential errors in processing steps. The
samples were regular 57% cocoa, 70% cocoa, 80% cocoa, excess lecithin,
prolonged roasting, no conching and long conching. In the RATA sensory method,
eleven employees in average age of 36 years was recruited at the company facility.
There was no specific requirement to serve as a panel. They were trained in
four sessions for between 35 to 45 minutes each. The panelists had very little
or no experience with the sensory evaluation, so they were introduced to the sensory
descriptors in the ballot, which had been prepared by the external trained and
experienced sensory panelist.  They were
also trained to explain the basic tastes using reference samples. Each sample
was a 10 g-chocolate piece, marked with a random three-digit code and presented
in random order. The panelists were served 2 samples at a time; and they needed
to pick all the descriptors that described the flavor and taste as well as
aftertaste of the chocolates. There were thirty-five descriptors in the ballot
and the frequency of sensory descriptors used would be counted. Then, the
panelists were asked to rate the intensity of the given descriptor using “little,
medium, or much” three-point category scale. The product effect on the RATA
scores for the sensory descriptors was analyzed by one-way ANOVA with Tukey’s
post hoc test to compare the product means. On the other hand, the DHS
technique using Tenax TA trap was applied to collect the extract aroma
compounds. The collected compounds were desorbed using a two-step automatic
thermal desorption unit. Then, they were analyzed by using GC-MS equipment. The
data collected was analyzed using the MSD Chemstation software.

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The outcome of RATA and DHS-GC-MS were
compared together. RATA method could capture excess lecithin, prolonged
roasting sensory deviations. However, the panelists could not detect the sensory
deviations of long conching chocolate sample in this study. The DHS-GC-MS were
able to give an overall chemistry profile of the volatile compounds in the
chocolate samples under different processed conditions, while RATA method was
fast, easy to perform and effective to analyze human’s threshold, which can influence
the consumer perception.