19 octobre 2020
Auditoire SUD 03 - Place Croix du Sud
Microbiological quality of grilled pork, smoked and smoked-dried fish in Benin: Problems and improvements by Dona Gildas Hippolyte ANIHOUVI
Pour l’obtention du grade de Docteur en sciences agronomiques et ingénierie biologique
Grilled pork (GP), smoked fish (SF) and smoked-dried fish (SDF) are popular foods in Benin. They are processed by small cottage industries for direct consumption at household level, as street food, or are intended for local and sub-regional markets. Although playing important socio-economic and nutritional roles, the conditions under which these foods are processed make their safety questionable. This study aimed to assess and improve their microbiological quality.
This work first consisted in a survey from processors with the aim to review the local knowledge on technologies of production of GP, SF and SDF. Practices of processing raw pork into GP and fresh fish into SF and SDF, the storage conditions applied, and the quality attributes of the end products were documented. The microbiological quality of GP, SF and SDF as sold to consumers were then assessed through samples collected from various processors. Out of 60 samples investigated, 26 (43%) were not compliant with the acceptable limits recommended by the Health Protection Agency (HPA) for Aerobic mesophilic bacteria (AMB), Enterobacteriaceae, Escherichia coli, Bacillus cereus and Clostridium perfringens. No sample contained Salmonella spp., Staphylococcus aureus or Listeria monocytogenes. A metagenomics approach was also used to explore the bacterial diversity of SF and SDF. The 48 SF and SDF samples randomly collected displayed substantial diversity profiles. Through a follow-up of processing trials, performed by experienced processors, several quality-compromising practices related to processors, raw material, processing methods and equipment were identified.
Based on these results, improved processing practices adapted to the cottage industries of pork grilling and fish smoking were proposed and implemented by the processors, and the safety of the end products was assessed. 100% of samples exhibited AMB loads ranged from 1.0 to 2.8 Log10 CFU g-1, which were far below the acceptable limit of 7.0 Log10 CFU g-1 recommended by HPA. Furthermore, Enterobacteriaceae, E. coli, B. cereus, C. perfringens and yeasts were not detected. Finally, a storage experiment was carried out on SDF using cardboard paper and old cloths as traditionally practiced by processors, and heat-sealed plastic bag as new packaging mode. The results showed that the storage in plastic bag preserved the microbiological quality and organoleptic properties of SDF for at least 180 days, while with the traditional method, a loss of safety and sensory quality was observed already after 30 and 60-day storage, respectively.
Jury members :
- Prof. Jacques Mahillon (UCLouvain), supervisor
- Prof. Victor Bienvenu Anihouvi (UAC, Bénin), supervisor
- Prof. Claude Bragard (UCLouvain), chairperson
- Dr. Marleen Abdel Massih (UCLouvain), secretary
- Prof. Marie-Louise Scippo (ULiège, Belgium)
- Prof. Véronique Delcenserie (ULiège, Belgium)
- Prof. Djidjoho Joseph Hounhouigan (UAC, Bénin)