Contamination, preservation, & spoilage of fish
- 2. Contamination, preservation, & spoilage of fish M.SRIDEVI II M.SC MICROBIOLOGY 18PY15 AYYA NADAR JANAKI AMMAL COLLEGE
- 3. Introduction Fish is found abundantly in all natural water It is a valuable source of food & has been used by man from ancient times Fish is a valuable source of high quality protein, minerals and vitamins Oily fish are rich in omega-3 poly unsaturated fatty acids
- 4. Contamination Fish contamination refers to fishes that are spoiled or infected Attack on fish by undesirable microorganism (bacteria ,fungi, yeast, mold, virus or other toxins & by products ) from external source is called microbial contamination of fish
- 7. Source of contamination From water From intestine At the time of catching Density microbes in surface slime From equipment From fish storage During transport
- 8. From water Fresh water fish carry fresh water bacteria Northern water carry mostly psychrophilic bacteria Tropical water carry more mesophiles bacteria
- 9. From intestine Both salt water and fresh water fish contain bacteria in the intestine The intestine fluid may contain 1000 to 100 million bacterial load per ml
- 10. At the time of catching The numbers of microorganisms on the skin of the fish can be influenced by the method of catching If some injury have done at the time of catching fish contamination may start
- 11. Density microbes in surface slime The slime that covers the outer surface of fish has been found to contain bacteria
- 12. From equipment Boats, catching net, boxes, fish house and fisher may be contaminated with bacteria & may transport into the fish during cleaning
- 13. From fish storage Contamination in fish can be started from when it kept in ice due to low quality of ice or the storage
- 14. During transport At the time of transporting fish from fishing place to shelling market, if the temperature is not maintained that is frozen temperature, contamination may start. During transporting, contaminated fish may contaminate the fresh fish
- 16. Spoilage of fish Food spoilage can be considered as any change that render the product unacceptable for human consumption Fish & other sea food may be spoiled by • Autoxidation (oxidation of unsaturated lipids) • Reaction caused by activities of the fish’s own enzymes • Metabolic activities of the microorganisms
- 17. Types of spoilage Microbial spoilage Physiological spoilage Biochemical spoilage
- 18. Process of spoilage The spoilage process starts immediately after the death of fish The process involves Autolysis Bacterial invasion & putrefaction Rigor mortis
- 21. Factors influencing kind & rate of spoilage The kind of fish The condition of the fish when caught Temperature : 0ᴼ- 1ᴼ Use of an antibiotic ice or dip The kind & extent of contamination of the fish with bacteria
- 22. 1) The kind of fish Flat fish spoil more rapidly than round fish because Under go rigor mortis more rapidly Deteriorate rapidly because of oxidation of unsaturated fats of their oils
- 23. 2) The condition of fish when caught Fish that are tired as a result of struggle, lack of oxygen and excessive handling spoil rapidly Feedy fish that is full of food when caught are more perishable than those with an empty intestine tract
- 24. 3) Kind and extent of contamination of the fish with bacteria Contamination may be from mud, water, handler and the exterior slime and intestinal content of the fish Greater the load on fish, more rapid the spoilage
- 25. 4) Temperature Chilling the fish delay bacterial growth Warmer the temperature, shorter the storage life of fish 5) Use of antibiotic ice or dip Use of antibiotic ice or dip
- 27. Evidence of spoilage Bright color of the fish fades and dirty yellow or brown discoloration appears Slime on fish increases , especially flaps & gills Eyes gradually sink and shrink, pupil become cloudy and cornea opaque Gills turn light pink and grayish color Reddish brown discoloration develops towards the tail and is a result of oxidation of hemoglobin
- 29. Discolorations of fish Yellow to greenish – pseudomonas fluorescence, micrococcus Red or pink – sarcina, micrococcus, bacillus, yeast & mold Chocolate or brown – yeast
- 41. Reference https://www.slideshare.net/shakilahmed103/contamination-spoilage-preservation- of-fish https://www.slideshare.net/karthikBangaru/spoilage-of-fish-and-other-sea-foods https://www.slideshare.net/ArafinEashat/contamination-spoilage-and-preservation- of-fish-61287919