Regulatory compliance and microbiological stability of canned mackerel in tomato sauce marketed in Yaounde, Cameroon

Background: Canned fish constitutes a major and affordable source of animal protein in sub-Saharan Africa. In Cameroon, the urban market is highly dependent on imported canned products. Although commercial sterilization ensures extended shelf life, deficiencies in labeling, packaging integrity, and thermal processing may compromise product safety, particularly under tropical conditions.
Objective: This study assessed labeling conformity, physicochemical quality, packaging integrity, and microbiological stability of canned mackerel in tomato sauce marketed in Yaounde, Cameroon.
Methods: A cross-sectional analytical study was conducted between October 2018 and May 2019. Fifty-six cans (declared net weight: 155 g) representing seven brands (n = 8 per brand) were randomly collected from retail markets. Labeling compliance was evaluated according to Codex standards. Net weight, drained weight, pH, titratable acidity, and thermal stability (incubation at 37 °C for 7 days) were determined. Microbiological analyses included total aerobic mesophilic flora, staphylococci, and Enterobacteriaceae. Results were interpreted according to ICMSF criteria. Statistical significance was set at p < 0.05.
Results: All brands showed labeling non-compliance, mainly due to absence of storage instructions (100%). Significant net weight deficits were observed in two brands (maximum mean deficit –6.6 g; p = 0.002). At 25 °C, no microorganisms were detected (<10 CFU/g). After incubation at 37 °C, 16.1% of samples showed microbial growth (2.08–3.54 log CFU/g), significantly associated with can swelling (χ² = 6.84; p = 0.009). Two brands exhibited significant pH increases after incubation (p < 0.01).
Conclusion: Although commercially sterile at ambient temperature, certain products exhibited reduced safety margins under thermal stress. Strengthened regulatory control and systematic post-market surveillance of imported canned foods are warranted in tropical settings.