Author: Wong, Wai-ling
Title: The preservative effect of fish under modified atmosphere packaging with or without enzymes
Degree: M.Sc.
Year: 1998
Subject: Fishes -- Preservation
Fishes -- Packaging
Fishery processing
Protective atmospheres
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Department of Applied Biology and Chemical Technology
Pages: iii, 110 leaves : ill. (some col.) ; 1998
Language: English
Abstract: Fish contains highly proportion of protein and unsaturated lipid, therefore, it is a healthy and popular food in Hong Kong. Unfortunately, it is easy to deteriorate by microbial activities. The spoilage processes of fish are mainly divided into lipid oxidation and protein degradation. The spoilage bacteria are able to utilize the natural marine fish component, trimethylamine oxide (TMAO), as a terminal hydrogen acceptor after depletion of oxygen. This allows the microorganisms to growth under anoxic conditions. At the same time, trimethylamine (TMA) is produced generating unfavorable smell and causing economic loss. Besides, enumeration of bacteria affect the health of consumer and has a risk of food poisoning. According to these reasons, effective preservatives are required to prolong the shelf life of fish. Unfortunately, most of preservatives are harmful, change the tastes or texture of flesh or less efficiency. Therefore, the objectives of this project is to find out a safe and effective preservation methods to maintain the freshness of fish. In this study, fish (Sparus macrocephalus) was preserved under various combination of conditions of oxygen absorber, 40% or 66% carbon dioxide, with or without enzyme glucose oxidase or lysozyme. The freshness qualities were assessed by sensory determination, TMA content measurement, torrymeter testing and microbiological tests during the 21 days of storage at 4 C. The results showed that preservations with 66% carbon dioxide combined with lysozyme, sodium chloride and ethylenediaminetetraaceric acid (EDTA) or glucose oxidase were more effective for extending the shelf life of fishes than other methods of preservation investigated here. That means highly carbon dioxide combined with enzymes can performed synergistic antibacterial effects. The oxygen absorber also had great potential for antimicrobial activities and then prolonging the shelf life of fish. However, its antibacterial function reduced as it combined with enzymes during the preservation process.
Rights: All rights reserved
Access: restricted access

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