2. 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
3. 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
ďFrom water
ďFrom intestine
ďAt the time of catching
ďDensity microbes in surface slime
ďFrom equipment
ďFrom fish storage
ďDuring transport
8. From water- spoilage
ďFresh water fish carry fresh water
bacteria.
ďNorthern water carry mostly
psychrophilic bacteria.
ďTropical water carry more mesophiles
bacteria.
9. From intestine
ďBoth salt water and fresh water fish
contain bacteria in the intestine.
ďThe intestine fluid contains 1000 to
100 million bacterial load per ml
10. At the time of catching
ďThe numbers of microorganisms on
the skin of the fish can be
influenced by the method of
catching
ďIf some injury have done at the
time of catching fish contamination
may start
11. Density microbes in surface slime
ďThe slime that covers the outer
surface of fish has been found to
contain bacteria.
12. From equipment
ď Boats
ď Catching net
ď Boxes
ď fish house and fisher may be
contaminated with bacteria & may
transport into the fish during cleaning.
14. During transport
ďAt the time of transporting fish from
fishing place to shelling market, if
the temperature is not maintained
that is frozen temperature,
contamination may start.
ďDuring transporting, contaminated
fish may contaminate the fresh fish.
15. Contamination of fish in fish processing industry:
Contamination may occur from-
ď Fish processing instruments
ď Fish collecting ship
ďFish processing table.
ď The polluted environment of that processing
industry.
ďAuxiliary gutting device ( Used to clean fish and
their Gut), Filleting machine etc.
ď Contaminated ice may contaminate fish at the time
of freezing.
ďMicrobial contaminants may come from laborer. If
they are not neat and clean.
16. Spoilage of fish
ďFood spoilage can be considered as any change that render
the product unacceptable for human consumption.
ďFish & other sea food may be spoiled by
ďAutoxidation (oxidation of unsaturated lipids)
ďReaction caused by activities of the fishâs own
enzymes
ďMetabolic activities of the microorganisms
18. Process of spoilage
ďThe spoilage process starts immediately
after the death of fish
ďThe process involves
ďAutolysis
ďBacterial invasion & putrefaction
ďRigor mortis
21. Factors influencing kind & rate of spoilage
The kind of fish
The kind & extent of contamination
of the fish with bacteria
Use of an antibiotic ice or dip
The condition of the fish when
caught
Temperature : 0á´ź- 1á´ź
22. 1) The kind of fish
ďFlat fish spoil more rapidly than round fish because
ďUnder go rigor mortis more rapidly
ďDeteriorate rapidly because of oxidation of unsaturated fats
of their oils
23. 2) The condition of fish when caught
ďFish that are tired as a result of struggle, lack of
oxygen and excessive handling spoil rapidly
ďFeedy 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
ďContamination may be from mud, water, handler and
the exterior slime and intestinal content of the fish
ďGreater the load on fish, more rapid the spoilage
25. 4) Temperature
ď Chilling the fish delay bacterial growth
ď Warmer the temperature, shorter the storage life of fish
5) Use of antibiotic ice or dip
ďUse of antibiotic ice or dip
26. Evidence of spoilage
ďBright color of the fish fades and dirty
yellow or brown discoloration appears
ď Slime on fish increases , especially flaps &
gills
ď Eyes gradually sink and shrink, pupil
become cloudy and cornea opaque
ďGills turn light pink and grayish color
ď Reddish brown discoloration develops
towards the tail and is a result of oxidation of
hemoglobin
27. Bacteria causing spoilage:
At chilling temperature-
Pseudomonas,
Achromobacter,
Flavobacterium.
At ordinary
atmospheric temp-
Escherichia,
Proteus, Serratia,
Sarcina and
Clostridium.
At higher
temperature-
Micrococcus and
Bacillus.
28. Discolorations of fish
ďYellow to greenish â Pseudomonas fluorescence,
Micrococcus
ďRed or pink â Sarcina, Micrococcus, Bacillus, Yeast &
Mold
ďChocolate or brown â Yeast
30. Use of low temperature
ď for the effective preservation, very low temperature to the tune of
-40°C and maintained at -23°C approved.
ďThis way, fish stays in food condition for about 6- 7 months
31. chilling
ďChilling is an obtained by covering the fish with layers of ice.
ďChilling is effective for short term preservation suck as is needed
to the transport landed fish to nearby markets or to canning
factories etc.
ďChilling cant prevent spoilage altogether but in general the colder
the fish the greater the reduction in bacterial in enzymes activity.
32. Freezing
ďThis is more effective than chilling.
ď freezing is achieved either by using a mixture of ice and salt or
refrigeration.
ď the recommended level at which the temperature of the fish has to be
brought down is -30°C and the interior part of the fish has to be -20°C.
33. Drying
Drying involves dehydration i.e., the removal of moisture contain
of fish so that the bacterial decomposition or enzymatic autolysis does
not occur. Moisture contains should be reduce up to 10% either
naturally or by the artificial means.
34. salting
ď salt is the preservative agent used to lengthen the shelf life of fish and
fishery products.
ď this is used in almost all methods of preservation except in icing,
refrigeration and freezing.
ďThere many different kinds of salt, some being better than others for fish
curing.
ďA distinction must be made between the two chief techniques of salting:
wet salting and dry salting.
35. canning
ď this is a very effective method through costly.
ďProduct is very good and retains much of flavor.
ďFish is cleaned and then cut to proper boneless pieces in filleting plants.
ďThe pieces are then brined or pickled to improve taste.
ďPreliminary cooking is then put in cans.
ďCooked pieces are then put in cans.
ďFinal cooking combines sterilization with stream and high.
36. Preservatives
Numerous chemicals are being used as preservatives to fight the great
perishability of fish.
ďBenzoic acid
ďSorbic acid
ďBoric acid
ďformaldehyde
37. Antioxidants
Several types of antioxidants are being used to
preserve fish specially on those kinds which are fatter
then others. It prevents undesirable changes in the un
saturated fat of fish.
38. Smoking
ď This is a simple method of preservation, for consumption either
directly after curing or within 12 hours.
ďRe smoking and roasting can keep the product in good condition for a
further 12 hours.
ďSalted fish can also be smoked by this method, but this is used mostly
for immediate consumption or in order to bring the produce in smoked
form to a nearby market