Evaluation of fish handling techniques employed by artisanal fishers on quality of Lethrinids and Siganids fish genera at landing time along the Kenyan coast using sensory and microbiological methods

Abstract

In artisanal fishery, traditional handling methods such as tossing fish onto the boat bottom or into woven mat baskets and gunny bags after capture are commonly employed. These practices accelerate fish spoilage due to cross contamination and exposure to high ambient temperature. This study aimed at investigating the effect of non-icing (onboard handling methods) on the quality of Lethrinids (Emperor fish, local name: Changu) and Siganids (Rabbitfish, local name: Tafi) landed along the Kenyan coast in comparison to iced fish. Monthly, samples were assessed by sensory methods using Quality Index Method (QIM), Total Viable Counts (TVC) and hydrogen sulphide (H2S) producing bacteria considered as specific spoilage organisms (SSO) counts for raw fish; Quantitative Descriptive Analysis (QDA) and Torry score for cooked fillets. Iced fish was characterised by better freshness quality attributes at landing time compared to non-iced at both landing sites. According to the QIM, iced treatment recorded better quality scores that were significantly different from non-iced groups (p<0.05) throughout the study with regard to fish genera. Cooked fillets showed both treatments to be within human consumption limits although non-iced fish were characterised by marginal quality attributes. Microbial assessment depicted TVC to be on average 10²- 10³ CFU/g and 10³- 10⁴ CFU/g in iced and non-iced Lethrinids respectively at both sampling sites. In Siganids higher numbers of 10⁴- 10⁵ CFU/g were recorded in non–iced group, with H₂S producing bacteria constituting a higher proportion of TVC. Iced Siganids recorded 10²- 10³ CFU/g throughout the study. Fish quality was reported to be inconsistent over the sampled month which reflects the large pressure systems of the Western Indian Ocean and the two distinct monsoon periods considered to differ in warmth. The major cause of deteriorated fish quality observed at landing time in the fishery was attributed to bacterial proliferation accelerated most importantly by non-icing onboard handling practises reported such as tossing fish onto the boat bottom or into woven mat baskets and gunny bags employed by the fishers. Sensory evaluation of cooked fillets and microbiological analysis showed fish was acceptable for human consumption regardless of handling method employed. This assures consumers of acceptable fish quality at landing time as long as good hygienic practices are observed at subsequent stages to consumption.

Key words: Lethrinids, Siganids, Quality, Sensory, Handling