Development of an analytical method for the screening of meaty flavors in commercial foodstuff by SPME-GC/O-MS

Abstract: The aim of the project was to develop a methodology for the chromatographic analysis able to identify the key odorants in meaty food products. The approach was based on the analysis of an already in market product and the theoretical background of the meaty flavors sensorially. Firstly, a custom-made flavor was created for the experiments covering as much as possible a broad area of compounds precipitated as meaty odors. Secondly, the extraction method was optimized to obtain a rich in compounds headspace. The extraction method used was the solid phase micro-extraction (SPME). Finally, the SPME-GC/O-MS method was holistically optimized using the previously identified odorants as target compounds. The tested parameters were eight. Specifically, four different fibers and three different values for sample quantity, solute quantity, solute’s salt concentration, incubation temperature, incubation time, exposure time, desorption temperature. The procedure consisted of the preparation of the samples within their respective quantities of solute and sample. Also, the gas chromatography methods were changed, in order to examine the different parameters. The results of GC-olfactometry revealed the presence of eighteen odors. More than half of the odorants were successfully identified from all three identification parameters, exactly ten odorants. Among them 1-Octen-3-one (mushroom-like), 2-Methyl-3-furanthiol (meat-like) 2-Furfurylthiol (coffee), 2-Methoxyphenol (smoky), (E)-2-nonenal (fatty, greeny), dimethyltrisulfide (cabbage-like), Furaneol (caramel), 2-Ethyl-3,6-dimethylpyrazine (roasty) and 2-Ethyl-3,5-dimethylpyrazine (roasty). The majority of odorants are either Maillard reaction products or lipid degradation products. Combination of SPME with GC/O-MS allowed to identify 10 out of 18 detected odorants. These odorants together were used as marker compounds for the optimization of the SPME method. The optimization was done in two steps: First the sample preparation, incubation time, incubation temperature, fiber type, exposure time and desorption temperature were selected. In order to optimize incubation time (10,15,20 min), incubation temperature temperature (40,60,80°C), exposure time (10,20,30min), desorption temperature (100,160,220°C), a fractional factorial design was used. Analyzing the results, is revealed that both the number of detected compounds as well as their peak area are mainly affected by fiber type, sample preparation, incubation time and temperature. The best results were generally achieved with PDMS/CAR/DVB 2cm fiber after hydration of the sample with water (20% of sodium chloride). The peak areas significantly III increased with incubation time and temperature. The majority of compounds showed maximum peak areas after incubation for 10 min at 80°C (5 out of 10) or 15 min at 80°C (3 out of 10).