Relative Microbial Spoilage of Un-gutted and Gutted Cultured Edible Barramundi (Lates calcarifer)

By Fahud Mohamed, Felicia Kow and Elkana Ngwenya.

Published by Food Studies: An Interdisciplinary Journal

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Article: Print $US10.00
Article: Electronic $US5.00

Freshness of fish plays an important role in the pricing and market acceptability of fish. Microbial activity is one of the most important factors affecting freshness of fish. Seafood products are vulnerable to microbial spoilage even in chilled storage. Fish flesh contains high levels of free non-protein nitrogen compounds which support post-mortem bacterial growth. Microbial spoilage consequently shortens the shelf-life of the seafood product—making the product unsuitable for consumption because of the growth of undesirable and health threatening micro-organisms. The microbial quality of fish and the shelf-life of fish are both of considerable importance in fish consumption. The consumption of deteriorating seafood poses risks to human health. Although legislation in many countries requires that fish be gutted prior to storage under chilled conditions, the evidence on the effects of gutting on the microbial status of fish is mixed. In this study, the bacterial spoilage of un-gutted and gutted Barramundi is assessed using a microbial assessment method (the standard total plate count (TPC)). Barramundi is a high value cultured fish with high demand in Australian domestic and foreign markets. The materials and methods employed are in accordance with the Australian Food Microbiology Standards AS 5013, AS 5013.1, AS 5013.5 for Total Plate Count (TPC). Sixteen fish, weighing an average of 450g were purchased from a Barramundi farm in Tasmania and processed within 30 minutes of harvest. TPC data from 148 agar plates are analysed using tests of proportions and analysis of variance (ANOVA). The effective sample size is therefore, n=148. The results of microbial tests suggest that gutted fish have a lower bacterial load in the initial days on ice. However, un-gutted fish seem to present relatively lower levels of bacterial counts, particularly after extended periods on ice. These results have implications for fresh fish transportation, storage, filleting and the processing of the different edible cutlets (portions) of Barramundi.

Keywords: Spoilage, Microbial, Total Plate Count, Gutted Fish, Un-gutted Fish, Barramundi (Lates Calcarifer)

Food Studies: An Interdisciplinary Journal, Volume 2, Issue 2, pp.31-41. Article: Print (Spiral Bound). Article: Electronic (PDF File; 491.330KB).

Fahud Mohamed

Graduate, National Centre of Marine Conservation and Resource Sustainability, University of Tasmania, Launceston, Tasmania, Australia

Recently completed a Bachelor of Applied Science (Honours) researching microbial spoilage of edible portions of farmed.

Dr Felicia Kow

Senior Lecturer, National Centre for Marine Conservation and Resource Sustainability, Australian Maritime College and University of Tasmania, Launceston, Tasmania, Australia

Dr. Kow is a Senior Lecturer in Seafood Quality and Safety. She holds a PhD in Food Science and Nutrition from London University, UK; a BSc in Food Science and Nutrition (Hons), London University, UK; a Grad. Dip. Environmental Sciences, Murdoch University, Australia; a RABQSA Food Safety Auditor Certification (Dairy, Aquaculture and Seafood); a Certificate IV in Training and Assessment (TAA4010); and a RABQSA National Food Safety Auditor Certification (Level IV High Risk).

Dr. Elkana Ngwenya

Lecturer, Marine Conservation and Resource Sustainability, Australian Maritime College and University of Tasmania, Launceston, Tasmania, Australia

Dr. Ngwenya is currently analysing various waves of the World Value Surveys and other Barometric Studies in order to ascertain local, regional, country and worldwide factors that influence pro-environmental behaviour. Her background is in Applied Economics, Quantitative Methods and Applied Social Science, with particular interest in theoretical and empirical behavioural modelling. Her current research interests are in Ocean Resource Use and Non-Use, Environmental Behaviour, and the Socioeconomics of Aquaculture for Rural Livelihoods.