Factors influencing storage & shelf life of fresh fish

1. Department of Fisheries and Aquatic Resources (DFAR) Sri Lanka National Aquatic Resources Research and Development Agency (NARA) Sri Lanka United Nations University Fisheries Training Programme (UNU-FTP) Iceland Icelandic International Development Agency (ICEIDA) Iceland Factors influencing storage & shelf life of fresh fish 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. Factors affecting shelf life of fish • Composition • Method of catching • Post harvest treatment • Processing (e.g. freezing, drying)

6. Intrinsic factors Biological properties influence fish composition and shelf life • 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.

7. Factors affecting composition of fish

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

9. 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 Post-harvest treatment

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

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

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

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 aw Fresh fish aW 0.9 Dried fish aW 0.3 Frozen fish aW 0.7 Water activity Shelf life

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

16. Rate of chilling & temperature control Rate of chilling Shelf life Variation of Shelf life with temperature RRS: Relative rate of spoilage H.H.Huss, 1995

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

18. Effect of packaging on the shelf life Huss 1995

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

20. 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 > 107- 108 cfu/g (in fish muscle) Time and temperaturehistory Methods to determine shelf life

21. Sensory analysis (Torry scheme) Influence of different temperature during storage (0°C, 7°Cand15°C) on the shelflife of haddock fillets Adapted from: Olafsdottir et al., 2006

22. Chemical and microbial analysisHaddock 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-schemefor Sea bass

24. Changes in sensory attributes during storage Gills have characteristic, red colour, mucus absent Eyes are clear and concave Eyes are cloudy, sunken 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). 1995. Quality and quality changes in fresh fish (chapter 6). FAO Fisheries Technical, Rome, FAO. • Olafsdottir G, Lauzon H, Martinsdottir E, Kristbergsson K. 2006. 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  2002. Quality management of stored fish in "Safety and quality issues in fish processing, Bremner, A. ed. Woodhead Publishing Ltd.. 303-313. • Training material from UNU-FTP/Icelandic Fisheries Laboratories Shewan, J.M., Macintosh, R.G., Tucker, C.G., Ehrenberg, A.S.C., 1953. 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, 283-298. • 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: 109-121 • K.W.S. Ariyawansa, D.N. Wijendra, S.P.S.D Senadeheera 2003. Quality Index Method developed for Frigate tuna (Auxis thasard). Sri land J. Aquat. Sci., 8:95-109