Screening of PAHs concentrations and determination of the total fat content and fatty acid profile of traditionally smoking fish in Central region of Cameroon.

Bc. Kateřina Šrámková

Master's thesis

Abstract:

Fish is the preferred food among the Cameroonian population, and with the advancement of aquaculture, traditionally smoked fish is going to play an increasingly large role in the Cameroonian diet. Smoked fish is an important source of nutrients and essential fatty acids; however, also a source of dangerous polycyclic aromatic hydrocarbon exposure. While PAHs are known to be produced during the traditional fish smoking process, the fatty acid and PAH content in Cameroonian smoked fish have rarely been investigated before. During field research and interviews with smoked fish producers within tree Yaoundé markets, 16 samples of 8 different fish species have been collected and further investigated for their fat content, FA profile, and PAH profile. Fat content was determined using a Soxhlet extractor and derivatizated for FA analysis via GC-MS. PAHs were extracted by a modified QuChERS method with EMR-Lipid and DLLME in triplicate, subsequently analyzed by GC-MS, and quantified using the internal standard (IS) method. The interval of fat content ranged between 3.22 % to 24.58 %, with significant differences among species and also within a single species. This was explained by a different origin, diet, age, and level of movement for sampled fish, and applicable to the FA profile as well. Moisture content varied greatly (7.04 % - 53.22 %) due to the non-uniform methods of smoking, in particular uncontrolled temperatures and time ranges between 1 hour and 1 week of smoking. FA profiles showed generally lower NQIs within samples than is reported on average, along with a total absence of EPA. However, the content of essential FAs (ALA and LA) was above average. Labeo coubie had the most positive NQI values, while Parachanna obscura displayed the highest total content of LC-PUFAs (including all-important DHA). The highest PAH maximum levels (MLs) for traditional smoked fish given by EC 1881/2006 were exceeded by 6 - 19 times for BaP (31.33 μg.kg-1 to 94.81 μg.kg-1) and 7 - 25 times for the sum of 4 PAHs (208.02 μg.kg-1 to 745.74 μg.kg-1). This could lead to developing carcinogenic and other diseases related to PAH exposure. Further research focused on PAH profile, FA profile, and traditional smoking methods in Cameroonian smoked fish was recommended.

Keywords

smoked fish, fat content, fatty acid profile, NQI, PAH, Cameroon

Language used: English

Date on which the thesis was submitted / produced: 15. 5. 2020

Thesis defence

• Supervisor: doc. Ing. Jan Banout, Ph.D.

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Master programme / field:
Tropical Agriculture / Sustainable Rural Development in the Tropics and Subtropics