Risk assessment for Listeria monocytogenes in traditionally processed fish from informal markets in Accra and Tema

Traditionally processed fish contributes significantly to food and nutrition security in Ghana. The processing and handling has however been associated with unsanitary and unhygienic practices with documented occurrence of food-borne pathogens. The products are also mainly sold on informal markets, where earlier studies reported the occurrence of Listeria monocytogenes in products sold therein. This study sought to determine the occurrence of L. monocytogenes in traditionally processed (smoked, dried, salted) fish sold on informal markets and to assess the exposure of consumers to the pathogen and the associated risk of illness. The study was based on the Codex Alimentarius protocol for microbial risk assessment. Surveys were conducted on selected traditional processors and consumers to determine processing practices and consumption patterns (frequency and portion sizes) respectively. Samples of traditionally processed fish were procured from some processors and consumer markets in the survey locations for microbial analysis to determine the occurrence and concentrations of L. monocytogenes in the processed fish. Microbial challenge tests were also done by cooking deliberately-contaminated fish for short and long time intervals to determine the survival of the pathogen during domestic cooking. Data from the survey (quantities of fish often consumed) and the laboratory analyses (microbial load) were used to assess the exposure of consumers to the pathogen, and also fitted to parametric (probability) functions to characterize the dose response using Monte Carlo simulations with the @Risk software (version 5.5, Palisade Corporation). Prevalence of L. monocytogenes in the fish products sampled from the markets was high (40-80%). However, the pathogen was not detected in smoked fish sampled immediately after processing, suggesting that post-processing contamination occurred. The concentrations of the pathogen in the products were generally low (102-3 CFU/g), and decreased from smoked fish through to sundried fish. The pathogen also survived in fish used for the challenge test. The estimated risks of illness were low, ranging from 1 in 100 to 1 in 100,000,000,000 chances of illness. Higher risks of illness were recorded for consumption of smoked fish than for sundried fish and salted fish, in that order. Consumers with high susceptibility to L. monocytogenes infection (elderly, children and pregnant women) were at a greater risk of illness than low risk individuals (non-pregnant adults aged 18 – 39 years). The findings suggest that consumers are exposed to ingesting L. monocytogenes through consumption of traditionally processed fish on informal markets. However the risk of illness is low. Improvements in hygienic processing and post-processing handling of fish as well as proper cooking of the fish products before consumption are recommended

FAO-Thiaroye processing technique : towards adopting improved fish smoking systems in the context of benefits, trade-offs and policy implications from selected developing countries

More than 60 percent of global production of smoked fishery products occurs in Africa and Asia, highlighting their tremendous significance in food and nutrition security and as a vehicle for livelihood support in these regions. However, prevailing processing technologies entail significant deleterious health implications for both processors and consumers. The main hazard relates to polycyclic aromatic hydrocarbons (PAHs), which are known to have carcinogenic potential. In response to the PAH challenge and leveraging on the Codex Alimentarius Code of Practice guidelines for preventing their occurrence in smoked and dried products, the FAO-Thiaroye fish processing technique (FTT) was developed under a collaborative research approach between FAO and a fisheries institution in Senegal. To date, the FTT has been introduced in 16 countries. The technique addresses the PAH problem, and yields products that comply with international limits on the hazard, while fostering many social, economic and environmental benefits. However, experience from some African and Asian countries points to the need for a context-driven balance that ensures that the gains associated with its use can be realized without making expensive compromises, especially in terms of fisheries resources status and trade dynamics. Policy and regulatory frameworks need to be informed by a risk-based approach and supportive of consistent benchmarking and differentiation of FTT products. This document reviews the lessons from those countries, and makes the case for a hard, evidence-based, policy backbone to safeguard the sustainable, eco-friendly supply of safe smoked (and dried) fishery products to support food security, particularly in the developing world

The shift from traditional to an improved fish smoking oven in Ghana : implications for food safety and public health

Smoked fish is a major animal protein source in Ghana. However, traditional processing methods result in contamination of the products with elevated levels of polycyclic aromatic hydrocarbon (PAHs). Unsatisfactory handling and storage practices also predispose the products to other food safety hazards. An improved oven, called the FAO-Thiaroye Processing Technique (FTT), has been introduced as an intervention. This study investigated the efficacy of the FTT through comparative fish smoking experiments with traditional ovens. Smoked fish from the test ovens were analyzed for PAHs [benzo(a)pyrene, benzo(a)anthracene, benzo(b)fluoranthene, chrysene], biogenic amines [β-phenylethylamine, putrescine, cadaverine, histamine and tyramine], Escherichia coli (hygiene indicator), Pseudomonas sp. (biogenic amine producer) and Salmonella sp. (microbial pathogen). PAHs were identified as the most relevant hazards in the products, with a 100% prevalence and a 100% exceedance of EU regulatory limits. Histamine levels (maximum 49 mg/kg) were below the regulatory limit (200 mg/kg), and Salmonella sp. was not detected in any of the samples. Whereas PAH levels in FTT products (max. 1.8 μg/kg for BaP and max. 8 μg/kg for PAH4) were below EU limits (2 μg/kg for BaP and 12 μg/kg for PAH4), in products of the traditional ovens, the levels exceeded the regulatory limits by up to 33 times. A risk assessment showed that the FTT significantly reduced consumer exposure to the hazard. A sensory evaluation suggested consumer acceptance of FTT products. A multicriteria decision analysis considering food safety, consumer acceptance, occupational health, economic and environmental factors showed that the FTT is a viable intervention for reducing exposure to PAHs in smoked fish in Ghana, although its adoption would require significant financial inputs. The findings highlight the public health risks associated with the use of the traditional ovens, and the potency of the FTT to reduce such risks