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

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, Handlin

Lipid oxidation and organoleptic response during shelf storage of some smoked marine fish in Kenya.

Peroxide Value (PV), Thiobarbituric Acid Reactive substances (TBARS),organoleptic properties and shelf life of some smoked marine fish namely Gerres oyena (“Chaa”), Lutjanus argentimaculatus (Red snapper) and Valamugil seheli (Mullet) were studied during storage. Both PV and TBARS for all the fish increased to a peak with storage time then decreased. PV in G. oyena was 10.80±1.07 mEq/kg on day 1 of storage, increased to 18.17±0.39 mEq/kg in day 8, peaked at 21.48±0.44 mEq/kg in day 11 then decreased to 8.50±2.34 mEq/kg on day 28. TBARS increasedfrom 0.39±0.09 mg malondialdehyde/kg when fresh to 0.59±0.09 mgmalondialdehyde/kg in day 8 then decreased to 0.07±0.004 mg malondialdehyde/kg on the 19th day of storage. PV in L. argentimaculatus was 61.65±0.09 mEq/kg on the 4th day of storage, increased to 112.86±0.19 mEq/kg on day 6 then decreased to15.17±0.54 mEq/kg on day 11. TBARS in L. argentimaculatus was 0.93±0.36 mg malondialdehyde/kg when fresh, 0.16±0.01 mg malondialdehyde/kg on day 1, 1.87±0.03 mg malondialdehyde/kg on day 8 and 0.06±0.01 mg malondialdehyde/kg on day 23. In Valamugil seheli, the PV was 57.59±0.11 mEq/kg on day 1 of storage, 76.55±0.49 mEq/kg on the 8th day, then it decreased to undetectable levels on the 28thday. The TBARS for fresh fish was 0.83±0.10 mg malondialdehyde/kg. After smoking it was 3.96±0.12 mg malondialdehyde/kg on day 4, 3.74±0.03 mg malondialdehyde/kg on day 8 then0.12± mg malondialdehyde /kg after 19 days of storage. The shelflives of the three fish species were monitored organoleptically during a 15day storage period on day 1, 5 and 15 with any score of 5 or below out of 9 being the limit for rejection. The fish were stored on laboratory benches in the open at ambient temperatures of 30 0C and humidity of 60%. Organoleptic tests based on various attributes were done to establish consumer preference for the fish. The freshness score for G. oyena was 6.38, V. seheli 7.2 and L. argentimaculatus 7.5 at the end of 15 daysstorage. There was a significantly better score (