| Author: | Kwong, Lap-chi |
| Title: | The effectiveness of biological preservatives and modified atmosphere packaging in preservation of Sparus macrocephalus, Pomadasys hasta and Lutjanus johni |
| Degree: | M.Sc. |
| Year: | 1998 |
| Subject: | Fishes -- Preservation Fishes -- Packaging Protective atmospheres Fishery processing Hong Kong Polytechnic University -- Dissertations |
| Department: | Multi-disciplinary Studies Department of Applied Biology and Chemical Technology |
| Pages: | vii, 114, [21] leaves : ill. (some col.) ; 30 cm |
| Language: | English |
| Abstract: | In this study, Modified Atmosphere Packaging (MAP) and biological preservatives (Glucose oxidase and Lysozyme /EDTA /sodium chloride system) were used to investigate their effectiveness in fish preservation. Different evaluation methods were used to evaluate the fish freshness. These included sensory evaluation, microbial analysis, physical property measurement, chemical and biochemical analysis. In phase I, Black Seabream (Sparus macrocephalus) was used to undergo preservative treatments with different combinations of preservatives and MAP including the addition of Glucose oxidase (GOX) system, addition of Lysozyme /EDTA /sodium chloride system, the use of increased carbon dioxide concentration as MAP, addition of deoxidizer and their combination use. With the use of deoxidizer in preservating, lower number of colonies on agars during 21 days of storage was observed or deoxidizer could lower down the bacteria multiplication rate by absorbing the molecular oxygen in atmosphere of the package. Lower TMA content was observed during 21 days storage compared with other conditions. The sensory scores showed that the fish with deoxidizer used were still acceptable at day 14. The use of deoxidizer was chosen as the method used in phase II. Because the relatively low cost and potential usefulness in actual situation, there was reason for more investigation. In phase II, Pomadasys hasta and Lutjanus johni were used to undergo storage conditions with or without deoxidizer by using air as packaging atmosphere. The evaluation results of Pomadasys hasta and Lutjanus johni in phase II was not much better than that of the control condition in TMA, Microbial, Torrymeter and Sensory evaluations. The reason might be due to the use of the bag of deoxidizer which was opened at the time at phase I. The deoxidizer packets might become less effective as the deoxidizer had contacted air in atmosphere during the time in phase I. Lastly, Seafood Freshness Indices ( SFI) -- Fresh SFI and Threshold SFI were established for Sparus macrocephalus, Pomadasys hasta and Lutjanus johni. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b14421872.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 5.73 MB | Adobe PDF | View/Open |
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