Microbiological and Chemical Changes of Nile Tilapia (<em>Oreochromis niloticus</em> L.) Fillet during Ice Storage: Effect of Age and Sex

Abstract

Fish is one of the most highly perishable food products. The aim of this study was to investigate microbiological and chemical changes of Nile tilapia fillet during ice storage. Nile tilapia samples were collected from Lake Zeway, Ethiopia. The fillet was stored at 0°C for 30 days on ice. Total plate count, total and fecal coliform, total volatile base nitrogen and pH was measured at the interval of four days. Regardless of age and sex, Total plate count varied between 4 to 11.74 log cfu/g. Total coliform counts fluctuated between <3 to >1100 MPN/g. However fecal coliform changed between 23 to <3 MPN/g. Total volatile base-Nitrogen has increased from 7.5 to 42.0 mg N/100 g. Similarly, pH has increased from 6.1 to 7.6 during the ice storage period. The eventual increase observed in mean total plate count could be due to multiplication of organisms favored at the storage condition. The increased total coliforms may be attributed to fillet quality and temperature fluctuations. The increment in TVB-N during ice storage is associated with activity of micro-organisms during later stages of deterioration. The increase in pH values is due to the formation of basic decomposition products. Finally, Post mortem change of Nile tilapia fillet was noticed and bacterial metabolites like Total volatile base-nitrogen, Total plate count and pH were invariably increased throughout the storage time indicating that they are good parameters to predict shelf life.

The Effects of Short‐Time Temperature Abuse on the Microbial and Sensory Quality of Chilled Saithe (Pollachius virens) Fillets

“…For this reason, higher pH coupled with higher microbial counts increases with longer holding and storage time, that is, with increased spoilage. A similar trend has been reported in previous shelf‐life studies on fish products (Magnusson and others , ; Okeyo and others ; Susanto and others ; Lema Abelti ). Likewise, the slower increase in pH in the fillets packed immediately after processing was explained by delays in bacterial growth and spoilage.…”

Changes in Sensory and Microbiological Quality Indices of Nile Tilapia (Oreochromis niloticus) and Grey Mullet (Mugil cephalus) During Ice Storage

“…The present results are not in accordance with those obtained by Abelti (2013) who reported that bacterial count was ranged from 6.33 CFU/g on day zero and 11.74 CFU/g on day 26 of storage in ice.…”

“…Finally the number of colonies were counted and multiplied by dilution factor to calculate the total colonies forming units per g sample (Abelti, 2013).…”

Rheological and structural properties of Hemiramphus far skin gelatin: Potential use as an active fish coating agent

“…The total volatile basic nitrogen (TVB-N) value was estimated by the micro-diffusion method (Abelti, 2013) following the distillation of the perchloric acid of the homogenized fish samples. The distillate was collected in a flask containing aqueous solution of boric acid and methyl red as an indicator.…”