Fish Processing

Presented by

Aditya Parmar

Food Safety and Quality Chains

UniHohenheim

Contents

Industry Senario

Decomposition Process

Preservation Process

Take Home Messages

History

Fishermen and sea creatures, mosaic, 1st century AD Copyright 2004 Bridgeman

A medieval view of fish processing, by Peter Brueghel the Elder (1556).

Source: Wikipedia

World Fish Production

India has a coastline of more than 7,000 km. The total navigable length of inland waterways is 14,500 km.

Per Capita Consumption

5kg

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).

World Comparision

Source: Wikipedia

India reprents about 5-6 % of the world fishing production

Source: DAHD&F 2005

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.

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

Composition

Water

FatsProtien

Vitamins Minerals

65-80%

1-20%

14-20%

Sea Food is Highgly perishable due to: 1. High moisture

content .

2. Avialability of nutrients for the growth of micro organisms.

3. Ambient temperature.

Fatty and White Fish

Decomposition

Enzymatic

BacterialOxidative

Spoilage Indications: 1. Change in colour.2. Odour, texture.3. Colour of eyes.4. Colour of gills.5. Softness of the

muscle. 

Enzymatic spoilage1. 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.

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 TriglyceridesTriglycerides Free Fatty Acids Peroxides, Ketones and Aldehydes

Oxidation results in: 1. Rancid Odors 2. Colour Changes

Bacterial Spoilage

Reduction of TMAO to TMAOdourless TMAO which is reduced to an offensive smelling TMA.

Breakdown of Amino Acids and formation of Primary AminesExamples are formation of histamine from histidine, arginine from glutamic acid etc. This bacterial action may cause food poisoning in extreme cases.

Breakdown in UreaThe 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.

Decomposition Processes

Deterioration processes in fish

Lipids Proteins

Chemical, bacterial and endogeneous enzyme reactions

Oxidation of fatty acidsHydrolysation of lipids to free fatty acids

Hydrolysation of proteins to peptides andamino acidsDeamination of amino acidsDecarboxylation of amino acids

So, the answer is - Preservation

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.

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

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.

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

4. Other Methods 1. Techniques based on the control of the oxydo-reduction potentialReducing 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 techniquesTwo 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.

Fish Meal and Fish Oil20 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

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.

Thankyou for your attention