3. History
A medieval view of fish
processing, by Peter Brueghel the
Elder (1556).
Source: Wikipedia Fishermen and sea creatures, mosaic, 1st century
AD Copyright 2004 Bridgeman
4. World Fish Production
India has a coastline of more than 7,000 km. The total
navigable length of inland waterways is 14,500 km.
6. Industry Senario
Source: FishStat FAO
The bulk of the catch comprises oil sardines, followed by penaeid
and non-penaeid shrimp, Indian mackerel, Bombay duck, croakers,
smaller quantities of cephalopods, other sardines and threadfin
breams.(CMFRI 2008).
8. World Trade
The share of Indian fish exports in world trade is
only about 6.5%. This invites urgent steps to
increase the share from India.
9. Domestic Demand
The projected demand for fish in the country by 2012 is 9.74 million tons,
which can be met by the projected supply of fish of 9.60 million tons by 2012
10. Composition
65-80%
Water
Sea Food is Highgly
perishable due to:
1-20%
Fats 1. High moisture
content .
2. Avialability of
nutrients for the
growth of micro
Protien organisms.
14-20%
3. Ambient
temperature.
Vitamins
Minerals
12. Decomposition
Spoilage Indications: Enzymatic
1. Change in colour.
2. Odour, texture.
3. Colour of eyes.
4. Colour of gills.
5. Softness of the
muscle.
Oxidative Bacterial
13. Enzymatic spoilage
1. After the death, the normal circulatory system breaks down and chemical
signals leak into the muscle causing them to stiffen. This process is known as
Rigor Mortis.
2. The blood circulation stops and the supply of oxygen is prevented. The
enzymes present in the muscle convert glycogen into lactic acid. The pH of the
fish muscle falls.
3. After the completion of rigor mortis, muscle stiffness gradually decreases
accompanied by increase in pH, ending up in softening of muscle. This is
followed by breakdown of proteins by enzymes. This process is called as
autolysis. Autolysis of protein starts immediately after rigor and creates
favourable conditions for the growth of bacteria.
4. ATP to AMP and Hypoxanthine. Thus the estimation of Hypoxanthine content
in fish indicates the degree of freshness.
5. Enzymatic action also causes decomposition in the fish known as belly
bursting.
14. Oxidative Deterioration
The most common chemical action which causes spoilage is the
oxidative rancidity in fatty fishes.
The levels of peroxide value and free fatty acid content both a
measure of oxidative rancidity are considered an index of quality
of fat fishes.
Oil – Mainly Triglycerides
Triglycerides Free Fatty Acids Peroxides, Ketones and
Aldehydes
Oxidation results in:
1. Rancid Odors
2. Colour Changes
15. Bacterial Spoilage
Reduction of TMAO to TMA
Odourless TMAO which is reduced to an offensive smelling TMA.
Breakdown of Amino Acids and formation of Primary Amines
Examples are formation of histamine from histidine, arginine from
glutamic acid etc. This bacterial action may cause food poisoning in
extreme cases.
Breakdown in Urea
The high concentration of urea in the flesh of some fishes is degraded
to ammonia by the microorganisms. The formation of ammonia is
accompanied by an offensive odour.
16. Decomposition Processes
Deterioration processes in fish
Lipids Proteins
Chemical, bacterial and endogeneous enzyme reactions
Oxidation of fatty acids Hydrolysation of proteins to peptides and
Hydrolysation of lipids to free fatty acids amino acids
Deamination of amino acids
Decarboxylation of amino acids
18. 1. Temperature control
Principle - Decrease the fish temperature to levels where metabolic
activities are reduced or completely stopped (0 C or < - 18 C) .
1. The design (size, insulation, palletization) and management of
cold stores are key for fish quality and energy saving.
2. Development of alternative refrigerants to replace the
chlorofluorocarbons (CFCs) which are damaging to ozone layers.
19. 2. Control of water activity
Water activity (aw) is a parameter that measures the availability of
water in fish flesh. Water is necessary for microbial and enzymatic
reactions and several preservation techniques have been developed
to tie up this water (or remove it) and thus reduce the aw.
1. Drying 2. Salting 3. Smoking 4.Freeze-drying
http://www.aqualab.com
20. 3. Physical control
Use of heat (cooking, blanching, pasteurizing, sterilizing), ionizing
irradiation (for pasteurization or sterilization) or microwave
heating.
Refrigeration is required to preserve fish products and increase their
shelf life.
Sterilised products and which are stable at ambient temperatures (<
40 C). These require packaging in metal cans or retortable pouches
before the heat treatment, thus the term "canning".
30°
60°
Source: Paulo et al.
21. 4. Chemical control
Principle: These techniques are designed to add anti-microbial
agents or decrease the fish muscle pH.
•Most bacteria stop multiplying at pH < 4.5.
•The decrease of pH is obtained by fermentation, marinades or by
adding acids (acetic, citric, lactic, etc.) to fish products. This
technique is often referred to as bio-preservation.
•Preservatives include nitrites, sulphites, sorbates, benzoates or
natural ones such as essential oils.
http://www.microscopesblog.com
22. 4. Other Methods
1. Techniques based on the control of the oxydo-reduction
potential
Reducing the oxygen around fish will increase its shelf life. By
vacuum packaging or by controlling or modifying the atmosphere
around the fish. Specific combinations of CO2, O2 and N2
characterize controlled (CA) or modified atmosphere (MA).
Vacuum packaging, CA and MA storage are often combined with
refrigeration for fish preservation
2. Combination of several preservation techniques
Two or more of the above-described techniques can be combined to
improve preservation efficiency . Combinations already in use include
pasteurization-refrigeration, CA (or MA)-refrigeration, salting-drying,
salting-smoking, drying-smoking and salting-marinating.
23. Fish Meal and Fish Oil
20 percent of world catch processed into fishmeal and fish oil. Oil is for
industrial uses in leather tanning and in the production of soap, glycerol
and other non-food products.
Only where it is uneconomic or impracticable for human
consumption, should the catch be reduced to fishmeal and oil.
Cycling fish through poultry or pigs is a loss because there is a need for 3
kg of edible fish to produce approximately 1 kg of edible chicken or pork.
1. Feed for Domestic
Animals
2. High Quality Organic
Fertilizer
24. Take Home Message
Most spoilage of fish is due to bacterial breakdown.
One spoilage characteristic found in fish and not in muscle foods
is trimethylamine (TMA) formation.
This odoriferous amine is responsible for the fish smell associated
with spoiling fish.
Fish meat has high level of polyunsaturated fatty acids,
which are unstable.
Chilling of fish immediately after harvest is very important
part of preservation.
India is bordered by Bay of Bengal, Arabian Sea and Indian Ocean and has a coastline of more than 7,000 kms. It has an extensive network of inland waterways and seaports. The inland waterways include rivers, canals, backwaters and creeks. The total navigable length of inland waterways is 14,500 km. Inland Waterways Authority of India (IWAI) is the statutory authority in charge of the waterways in India. There are three national waterways in India: Allahabad Haldia stretch of the Ganga Bhagirathi Hooghly river, SadiyaDhubri stretch of the Brahmaputra river system and KollamKottapuram stretch of West Coast Canal along with Champakara canal and Udyogmandal canal. These waterways also attract tourists from all parts of the world, thus promoting Indian travel & Tourism. There are also many hotels and resorts in these areas to cater to the lodging needs of the tourists. There are 12 major ports and about 180 minor and intermediate ports in India. With the ports handling more than 95% of the trade in India, they act as the major gateway for trade. The major ports in India are Calcutta, Haldia, Paradip, Visakhapatanam, Ennore, Chennai, Tuticorin, Cochin, New Mangalore, Mormugao, JNPT, Mumbai and Kandla.
Enzyme actionThe Rigor mortis is a physical effect on the muscle tissue of fish caused by chemical changes following the death. In live fish, its movements are controlled by chemical signals which cause the eythmic contraction (stiffing) and relaxation of the muscles. This produces swimming action. After the death, the normal circulatory system breaks down and chemical signals leak into the muscle causing them to stiffen. This process is known as Rigor Mortis. In other words, in live fish the glycogen present in the muscle is converted to carbon dioxide and water after supply of oxygen to the cells. After the death of fish, the blood circulation stops and the supply of oxygen is prevented. The enzymes present in the muscle convert glycogen into lactic acid. The pH of the fish muscle falls. The formation of the lactic acid continues till the supply of glycogen is completely used up.After the completion of rigor mortis, muscle stiffness gradually decreases accompanied by increase in pH, ending up in softening of muscle. This is followed by breakdown of proteins by enzymes. This process is called as autolysis.Thus autolysis can be described as an internal breakdown of the structure of the protein and fats due to a complex series of reactions by enzymes. Autolysis of protein starts immediately after rigor and creates favorable conditions for the growth of bacteria.Another important action of the enzymes is that it affects the flavor of fish. The components responsible for the taste and flavor of the fish are changed by the enzymatic action. An example is the progressive, degradation of ATP to AMP and Hypoxanthine. Hypoxanthine is produced by the breakdown of ATP which is a main component of fish muscle nucleotide. The accumulation of Hypoxanthine imparts a bitter taste in the fish muscle accompanied by loss of fresh fish flavor. Thus the estimation of Hypoxanthine content in fish indicates the degree of freshness.Enzymatic action also causes decomposition in the fish known as belly bursting. The belly bursting is caused by the action of digestive enzymes present in the gut of the fish.The black spot formation in shrimps is also caused by the action of the enzymes on the amino acid. The black colour is due to the formation of Melanin (Black Pigment) by the action of enzyme tyrosinase on tyrosin present in the shrimps. Black spots present a poor appearance and therefore, are not acceptable.
Trimethylamine (TMA)TMAO trimethyamine oxid
Effect of heat stress on mixed cultures of bacteria isolated from horse mackerel (Trachurustrachurus) and on subsequent growth of the bacteria in nutrient broth on ice. o, 30°C and D, 60°C (::!:20n-I).
Effect of heat stress on mixed cultures of bacteria isolated from horse mackerel (Trachurustrachurus) and on subsequent growth of the bacteria in nutrient broth on ice. o, 30°C and D, 60°C (::!:20n-I).
Also, a significant proportion of the world catch (20 percent) is still processed into fishmeal and fish oil. Fishmeal is a ground solid product that is obtained by removing most of the water and some or all of the oil from fish or fish waste. This industry was launched in the 19th century, based mainly on surplus catches of herring from seasonal coastal fisheries to produce oil for industrial uses in leather tanning and in the production of soap, glycerol and other non-food products. Presently, it uses small oily fish to produce fishmeal and oil. It is worthy to mention that, only where it is uneconomic or impracticable for human consumption, should the catch be reduced to fishmeal and oil. Indeed, cycling fish through poultry or pigs is a loss because there is a need for 3 kg of edible fish to produce approximately 1 kg of edible chicken or pork.
