In thefood industry, the characteristics of the product, such as flavor, texture and consistencyof the product all affect to the consumer perception. Therefore, the qualityevaluation of final products plays an important role in chocolate production.
Manytechniques have been applied to the food production and be a part of qualitycontrol program to have profile of the final product. Although the modern technologydynamic headspace sampling (DHS) and gas chromatography with mass spectrometry(GC-MS) can separate and identify the off-flavor compounds in chocolate, itcannot account into the consumer perception. Hence, a sensory evaluation isnecessary to analyze the human threshold to detect the volatile compounds inchocolate which can affect to the product quality.
This study was conducted ina small chocolate company in Denmark. The fast-sensory Rate-All-That-Apply(RATA) method was applied to this study to compare the effectiveness in capturingthe important sensory deviations with DHS-GC-MS technology. Thechocolate samples were produced especially for this study with regularprocessing production and some potential errors in processing steps. Thesamples 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 infour sessions for between 35 to 45 minutes each. The panelists had very littleor no experience with the sensory evaluation, so they were introduced to the sensorydescriptors in the ballot, which had been prepared by the external trained andexperienced sensory panelist. They werealso trained to explain the basic tastes using reference samples. Each samplewas a 10 g-chocolate piece, marked with a random three-digit code and presentedin random order.
The panelists were served 2 samples at a time; and they neededto pick all the descriptors that described the flavor and taste as well asaftertaste of the chocolates. There were thirty-five descriptors in the ballotand the frequency of sensory descriptors used would be counted. Then, thepanelists were asked to rate the intensity of the given descriptor using “little,medium, or much” three-point category scale. The product effect on the RATAscores for the sensory descriptors was analyzed by one-way ANOVA with Tukey’spost hoc test to compare the product means.
On the other hand, the DHStechnique using Tenax TA trap was applied to collect the extract aromacompounds. The collected compounds were desorbed using a two-step automaticthermal desorption unit. Then, they were analyzed by using GC-MS equipment. Thedata collected was analyzed using the MSD Chemstation software.
The outcome of RATA and DHS-GC-MS werecompared together. RATA method could capture excess lecithin, prolongedroasting sensory deviations. However, the panelists could not detect the sensorydeviations of long conching chocolate sample in this study.
The DHS-GC-MS wereable to give an overall chemistry profile of the volatile compounds in thechocolate samples under different processed conditions, while RATA method wasfast, easy to perform and effective to analyze human’s threshold, which can influencethe consumer perception.