Résumé:
Sardina pilchardus is a small bony fish belonging to the class Actinopterygii, order
Clupeiformes, and family Clupeidae. It is a pelagic species of economic interest and
nutritional value, fished throughout the coast. However, landings of this species are currently
declining, whereas they used to be very high in all fishing areas along the Mostaganem coast.
The objective of this research study is to assess, on the one hand, certain physicochemical
parameters such as pH, total polyphenol and flavonoid levels, and the evaluation of
antioxidant activity by DPPH radical scavenging, and, on the other hand, to enhance the
nutritional quality of the Sardina pilchardus fish species by assessing the presence or absence
of bacteria from wastewater discharges. The methodology used to achieve all objectives
included the use of reactive strips to measure hydrogen potential (pH), bacterial culture using
specific culture media for each species to search for bacteria resulting from contamination
due to wastewater discharge. The assessment of water content, dry matter, and lipids was
carried out using evaluation protocols according to AFNOR standards. Biochemical
parameters such as total polyphenol and total flavonoid content, as well as the 50% Inhibitory
Concentration (IC50), were assessed using Soxhlet extraction of the crude extract of Sardina
pilchardus using ethanol as the solvent. The results for water content and dry matter were
satisfactory and were estimated at 76.2% and 23.8%, respectively. The fat content of sardines
was estimated at 11.5%. The determination of the potential of hydrogen (pH) at room
temperature was equal to 5.80, and for 15 days at 37°C and at 55°C for 7 days was estimated
at 5.
The mesophilic flora count (FTAM) was evaluated, which was around 14.102 CFU/g. The
total coliform count was estimated at 2.102 CFU/g. The fecal coliform count was zero. The
microbial flora count revealed no presence of colonies of Staphylococcus aureus and
Clostridium sulfito-reducers. The results show that the crude extract of Sardina pilchardus
had a 50% inhibitory concentration (IC50) of 0.806 mg/ml, while ascorbic acid had a 50%
inhibitory concentration (IC50) of 0.469 mg/ml. The total polyphenol content was estimated
at 0.033 mg EAG/g, and that of total flavonoids was estimated at 33.72 μg EQ/g. Based on
these findings, the Sardina pilchardus used in our research study exhibits very high nutritional
quality, primarily due to the absence of various bacterial species represented as health
indicators, including mesophilic flora, fecal coliforms, Escherichia coli, Staphylococcus
aureus, and sulfite-reducing Clostridium, except for total coliforms, where the number of
bacterial colonies was considerable but did not affect consumption.
Furthermore, this species exhibits antioxidant activity, owing to its ability to achieve 50%
inhibition and its varying levels of total polyphenols and flavonoids.
