2. Salmonella
Fresh fish collected from open sea is free from salmonella. However, fish from polluted costal
water is usually infected with salmonella.
Sources of contamination:
• Costal sea water
• Water from culture pond
• Mud form culture pond
• Sea beach sand
• Processed water
• Ice
• Floor
• Utensils
• Dropping of wall lizard seen on processing tables.
• Dropping of rodents seen on processing tables.
3. Standard pertaining due to presence of salmonella:
Organism should be totally absent in sea food.
It is generally accepted that presence of colony of salmonella at any level in
food material has to be regarded as potential hazards.
4. Prevention of contamination from salmonella:
1) Avoid fishing from polluted water.
2) Avoid washing with near shore water.
3) Avoid sorting of catch on sea beaches.
4) Use only chlorinated water (10ppm) for processing & for ice manufacturing.
5) Workers may be periodically examined to detect carriers.
6) Those who are suffering from vomiting should keep away from work.
7) Before starting work all fish handlers may wash & disinfect their hand.
8) Entry of rodents, wall lizards & flies to the processing hall may be avoided.
9) Before starting and after finishing each day work all the utensils used for
processing may be cleaned & disinfected.
5. V. cholerae
• Mostly shellfishes & crustaceans are involved in cholera out brakes.
• The Vibrio entered in the gastrointestinal tract of shellfish & survives for
1 1/2 month at 0 – 50°C & 15 – 20 days at 22°C. This survival period of
Vibrio increase to above 20 days in oyster & clams. V. cholera survives
only for a few days in fish stored at room temperature.
6. Control measures:
It is clear that environmental hygiene & sanitation play a significant role in
contamination of sea food with V. cholera.
Considerable stress has to give environmental sanitation & hygiene
surrounding of processing plant should be kept clean & disinfected.
Only potable water supply should be used & the water used for different
purposes should be properly chlorinated.
Further more stress should be given to personal hygiene for the fish handlers.
It is also advised to have periodical medical checkup of worker engaged in
processing & other operation related to processing.
7. Listiria monocytogen
Morphology: It is gram +ve, rod shaped aerobic, motile.
It can ferment carbohydrates & sugars.
Why Listiria monocytogen is important in sea food?
• It is deadly pathogen.
• It is a tough organism which survives at freezing & thawing.
• Relatively heat resistant.
• It can also survive the temperature of pasteurization.
• Grows in refrigerated temperature (10°C). It can survive during frozen
storage.
• Relatively resistant to common salt & nitrite.
• High mortality rate in case of human Listeriosis (about 30 %)
8. Habitat:
It is widely distributed in nature. The most common habitat of
this micro-organism is given below.
1) Sewage
2) Soil
3) Mud
4) Fecal matter
5) Fertilizer
6) Decaying vegetation
7) Insects
8) Warm blooded animals
9. Incidence of L. monocytogen in sea food:
Relatively very little is known about the incidence of L. monocytogen spp. in fishery
products.
A case of listeriosis on consumption of shellfish & fresh finfish has been documented
in Newzeland in 1984.
USFDA has also reported the incidence of this disease due to consumption of sea
food. So far there is no report about the incidence of this disease from India.
The temperature for the proper growth of this organism is ranges between 1 to 45°C.
It can also grow well in wide range of pH 5 - 9.6.
This pathogen can tolerate high concentration of NaCl.
Since this micro-organisms can resist pasteurization temperature, high conc. of NaCl,
can survive during frozen storage which is also called as unique micro-organism.
10. Control measures:
• So far nobody has develop perfect control measures for 100%
eradication of this micro-organism.
• The only possible control measure is following proper GMP & SSOP.
11. Shigella
Shigella is bacterium belonging to the family Entrobacteriaceae & is often
associated with intestinal diseases like abdominal pain, dysentery etc.
Morphology & cultural characteristic:
• Shigella is short gm - ve rods.
• They are non-spore forming, non capsulating, aerobic in nature.
• They can grow in temp range of 10-40°C. The optimum growth
temperature is 37°C.
12. Habitat:
This microorganism is found in intestine of warm blooded animals.
Disease cause due to this organism is called Shigellosis.
Transmission of the organism form one individual to another is by the
following means.
1. Direct hand to mouth through contaminated fingers.
2. Through contaminated food, water, ice etc.
3. Through contaminated contact surface.
4. Flies etc.
5. Through food handling who carries of this organism.
13. Significands
As this organism is transmitted due to improper personal hygiene & through
media water, ice, flies, food, contact surface etc.
The marine products which require more human handlings are susceptible to
contamination of these organisms.
Although food born shigellosis a very much less as compared to
salmonellosis.
There are few cases of shigellosis on consumption of marine products.
14. Control Measures:
The following care which prevent contamination:
1. Good personal hygiene.
2. Sanitary good handing practices.
3. Temp control.
4. Restriction of known carries from food preparation areas.
5. Use of properly chlorinated water and ice.
6. The best way to kill this pathogen is heating at 60°C for 10min.
15. Fungi
Among the method of preservation of fish salting and drying is cheapest. So this
method is used by the common fisherman to preserve the fish.
In hot and calm climate as seen in India, dried fish spoil very quickly. Fungi are
mainly responsible for spoilage of fish product.
Fungi are everywhere in nature, soil, air, water etc. They form spore which can
survive for longer period. These spores are carried away by different means.
The contamination of fish with fungi during drying takes place mainly from air and
soil.
Insets and birds also carry this fungi spore in their bodies and thus contaminate
the fish.
16. Characteristics of fungi:
• Fungi are plant like organisms but they do not contain chlorophyll since
they do not contain chlorophyll they cannot produce their own food and so
they live as saprophytes.
• Many saprophytic fungi can cause spoilage of agricultural and domestic
product and results in thousands of tones work of damage in year.
• Parasitic fungi may cause major losses to crop plants.
• Most of the dried fishery products are contaminated with fungi.
17. Factors Affecting Fungal Growth:
1. pH value: Most of the fungi tolerate wide range of pH provided other conditions
are favorable. In general slight acidity is favorable for the germination of fungal
spore and for their proper growth.
2. Nutrients in Fish: Fish is a nutritious commodity with high protein which can
provide a very favorable environment for the fungal growth. In case of naturally
dried fish complete removal of moisture is not possible and moisture present in the
dried fish will also provide suitable environment for fungal growth.
18. 3. Environmental Conditions: This factor includes temperature and gaseous
environment during food storage. The majorities of fungi associated with fish are
mesophillic in nature and grow better in the temp range of 20-450C. Growth of
some fungi has been reported at to extremely low level of oxygen.
4. Processing factor:
a) Heating: Most fungal spores are destroying by heating for 5 min. at 65°C or 1
min. at 80°C.
b) Radiation: Radiation process has been found to reduce the fungal spoilage of
various produce & extend the shelf life of the product.
19. 5) Added chemical preservatives:
Chemical preservatives active against fungi include benzoids, sorbate & ethylene
oxides, Sulpher dioxide which is primarily use to preserve color is an effective
preservative. Nisin is permitted in some countries to control fungal growth.
6) Water activity:
It is indicated by aw. It is defined as ratio of aqueous vapor pressure of the
substrate to the vapour pressure of pure water at the same temperature.
The majority of bacteria requires water activity of 0.95 for good growth. Most of
the fungi are able to grow at water activity level of 0.80. Some strains of fungi can
grow even at water activity as low as 0.65.
20. Spoilage of fish by fungi:
1) Change in color due to fungal growth.
2) Changes in flavor.
3) Lipolysis & proteolysis.
21. Control of fungal spoilage:
1) Chemical methods:
a) Use of preservatives: - Main preservatives used are Calcium propionate, potassium
sorbet, Sodium benzoate, Sulpher dioxide & Sodium nitrate.
b) Use of fungicides: - It is expensive to use & sometimes it can be toxic to human
beings.
c) By gamma-irradiation- This is also one of the effective methods of controlling the
fungal growth. The only disadvantage is expensive of this process are higher.
22. 2. Physical Methods:
Control of storage temp.
Control of water activity by controlling moisture salt and fat.
Keeping storage period as short as possible.
Adopting insect control measure, discarding damaged fish.
Appling proper curing methods i.e. avoid contamination from soil, dust, etc.
