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Factors influencing storage & shelf life of fresh fish Icelandic International Development Agency (ICEIDA) Iceland United Nations University Fisheries.

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Presentation on theme: "Factors influencing storage & shelf life of fresh fish Icelandic International Development Agency (ICEIDA) Iceland United Nations University Fisheries."— Presentation transcript:

1 Factors influencing storage & shelf life of fresh fish Icelandic International Development Agency (ICEIDA) Iceland United Nations University Fisheries Training Programme (UNU-FTP) Iceland National Aquatic Resources Research and Development Agency (NARA) Sri Lanka Department of Fisheries and Aquatic Resources (DFAR) Sri Lanka Quality and safety issues in fish handling A course in quality and safety management in fishery harbours in Sri Lanka NARA, DFAR, ICEIDA and UNU-FTP

2 Content What is shelf life Factors affecting shelf life How to determine shelf life

3 Learning Objectives After this lecture participants will be familiar with: Shelf life and factors affecting shelflife of fish raw materials. some monitoring method to determine shelf life of fish

4 Shelf life Shelf life can be defined as the period of time that the fish is fit for consumption The limit of shelf life i.e. when the fish becomes unfit for consumption can be determined based on sensory, chemical or microbial criteria Time and temperature of storage can also be used as criteria to determine the limit of shelf life Quality parameter rather than a safety parameter

5 Composition Method of catching Post harvest treatment Processing (e.g. freezing, drying) Factors affecting shelf life of fish

6 Larger fish spoil more slowly than small fish. Flat fish keep better than round fish Lean fish keep longer than fatty fish under aerobic storage. Bony fish are edible longer than cartilaginous fish. Intrinsic factors Biological properties influence fish composition and shelf life

7 Factors affecting composition of fish SeasonSpawning (fat content & water) AgeYoung, sexually mature fish SexFemale & male EnvironmentFeed, water temperature Body locationLight & dark muscles Type of fishSharks, Ray fish contain high urea Pelagic & demersal fish

8 Method of catching – Long line – Trawl net – Gill net – Beach seine  Quick landing  Not damaging to fish

9 Post-harvest treatment Handling on board Proper bleeding, gutting, cleaning - Rate of chilling (especially fatty fish) & temperature control GMP, hygiene, SSOP Packaging, storage & environmental conditions Unloading & auctioning Loading, transportation, retail sales & processing

10 Fish should reach the end consumer in minimum time Prolonged time lower the sensory quality of fish Time from the harvest

11 Number of unacceptable lots (out of nine) of skipjack tuna transported from Beruwala fishery harbour to Matugama & Horana. (Ganegamarachchi, et al 2002) Microbiological quality of fish

12 (Ganegamarachchi, et al 2002) Fluctuation of core temperature in skipjack tuna handled at different time periods along the Mathugama distribution

13 E. coli counts of skinned skipjack tuna in multi-day boats, at pier, in transport vehicles, at stall and at retailed stage (Ganegamarachchi, et al 2002)

14 Post harvest processing influences water activity and the rate of spoilage changes Water activity Shelf life Water activity aw Fresh fish a W 0.9 Dried fish a W 0.3 Frozen fish a W 0.7

15 Handling on-board 1.Quick landing 2.Stunning, brain spiking, bleeding 3.Gilling & gutting 4.Place in a chilling system for quick cooling 5.Transfer to ice storage

16 Rate of chilling & temperature control 0 C5 C10 C shelf lifeRRSshelf lifeRRSshelf lifeRRS Crab claw Salmon Sea bream Packed cod Calculated Variation of Shelf life with temperature Rate of chilling Shelf life RRS: Relative rate of spoilage H.H.Huss, 1995

17 Packaging methods for prolonging shelf life Modified atmospheric packaging Mechanical gas flushing and sealing with fish fillets Vacuum Packing

18 Effect of packaging on the shelf life Type of ProductStorage temp.Shelf life (weeks) AirVPMAP Meat (beef, pork, poultry) °C Lean fish (cod, pollock, rockfish, trevally) °C Fatty fish (herring, salmon, trout) °C Shellfish (crabs, scampi, scallops) °C ½ ½ - 3 Warmwater fish (sheepshead, swordfish, tilapia) °C ½ Huss 1995

19 Effect of transportation on shelf life of fish Proper packing & storage Use of boxes Adequate icing & cooling Hygienic conditions

20 Methods to determine shelf life Sensory evaluation –Torry or EU scheme for cooked fish, Quality Index Method (QIM) for raw/whole fish Chemical analyses –Unfit for consumption when for instance TVB-N, TMA, biogenic amines have reached a certain level. Microbiological analyses –Unfit for consumption when TVC > cfu/g (in fish muscle) Time and temperature history

21 Sensory analysis (Torry scheme) Influence of different temperature during storage (0°C, 7°C and 15°C) on the shelflife of haddock fillets Adapted from: Olafsdottir et al., 2006

22 Chemical and microbial analysis Haddock fillets stored at 0°C, 7°C and 15°C TVB-N (Total volatile basic nitrogen) TVC (total viable counts) and Photobacterium phosphoreum (Pp) Adapted from: Olafsdottir et al., 2006

23 QIM-scheme for Sea bass

24 Changes in sensory attributes during storage Eyes are cloudy, sunken Eyes are clear and concave Gills have characteristic, red colour, mucus absent Gills are discoloured with excessive mucus

25 A curve to predict the storage time remaining for herring stored in ice or sea water at 0°C

26 References Huss, H.H. (ed) Quality and quality changes in fresh fish (chapter 6). FAO Fisheries Technical, Rome, FAO. Olafsdottir G, Lauzon H, Martinsdottir E, Kristbergsson K Influence of storage temperature on microbial spoilage characteristics of haddock fillets (Melanogrammus aeglefinus) evaluated by multivariate quality prediction. Int. J Food Microbiol.111, 112–125. E. Martinsdóttir Quality management of stored fish in "Safety and quality issues in fish processing, Bremner, A. ed. Woodhead Publishing Ltd Training material from UNU-FTP/Icelandic Fisheries Laboratories Shewan, J.M., Macintosh, R.G., Tucker, C.G., Ehrenberg, A.S.C., The development of a numeric scoring system for the sensory assessment of the spoilage of wet white fish stored in ice. Journal of the Science of Food and Agriculture 4, Ganegama Arachchi, G.J. Kariyawasam, M.G.I.U., Heenatigala, P.P.M. Ariyaratne, T. Dahanayeka, T. and Jayasinghe, J.M.P.K. (2004) An investigation on the quality and handling practices of skipjack tuna (Katsuwonus pelamis) along the main commercial distribution channels of beruwala fishery harbour. Sri Lanka J. Aquat. Sci. 9: K.W.S. Ariyawansa, D.N. Wijendra, S.P.S.D Senadeheera Quality Index Method developed for Frigate tuna (Auxis thasard). Sri land J. Aquat. Sci., 8:95-109

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