Deterioration of Fish

SARDAR BAHADUR KHAN WOMEN UNIVERSITY (SBK)
ASSIGNMENT: POST HARVESTING TECHNOLOGY

SUBJECT: FISHERIES
SUBMITTED BY: NIDA YOUSAF, MEHAK
MEHMOOD, SANA ABDUL MUHAMMAD, SHABNUM
EJAZ, NAHEED QAMAR AND FATIMA GHOUS BAKASH
SUBMITTED TO: DR. SHAGUFTA SADOZAI
CONTENTS:
 Introduction
 What is Post Harvesting Management?
 Reasons for Losses
 Causes of food deterioration
 Post-Harvest Industries
 Other components of the system include.
 PRINCIPLES OF FISH PRESERVATION AND PROCESSING
 PROPER STEPS IN HANDLING FRESH FISH
 FISH PROCESSING
 FACTORS THAT AFFECT FISH SPOILAGE AND
DETERIORATION OF FISH
 FACTORS THAT INFLUENCE THE RATE OF FISH SPOILAGE
INTRODUCTION:
What is Post Harvesting Management?
 Post -Harvest Management includes the processes done immediately
after harvesting the produce, including cooling, cleaning, sorting and
packing. The instant a crop is removed from the ground, or
separated from its parent plant, it begins to deteriorate. Therefore,
Postharvest treatment are given to increase its shelf life and
maintain its quality. Thus, post-harvest management largely
determines final quality.
Post-harvest?
 For minimizing the qualitative as well as quantitative losses after
harvesting.
• 40% losses in fruits and vegetables due to improper handling, storage,
packaging and transportation
Reasons for Losses:

 Lack of clear concept of packing house operations.
 Lack of awareness among the growers, contractors and even the
policy makers.
 Lack of infrastructure.
 Late realization of its importance.
 Inadequate technical support.
 Inadequate post-harvest quality control.
 Unorganized marketing.
 Absence of pre-cooling and cold storage.
 Inadequate market facilities, market intelligence and market
information service (MIS)
 Poor storage facilities.
Causes of food deterioration:

1. Growth of microorganisms
2. Activities of natural food enzymes
3. Insects, parasites and rodents
4. Temperature
5. Moisture
6. Air
7. Light and time
Factors affecting post-harvest losses:

1. Variety
2. Management
3. Method and stage of harvesting
4. Improper grading and packing
5. Storing
6. Transport and marketing (Physical and mechanical damage)
Post -Harvest Industries:
The post -harvest industry includes the following main components
 Harvesting and threshing

 Drying and storage
 Processing (conservation and / or transformation of the produce)
 Utilization by consumer including home processing.
Other components of the system include.

 Transportation and distribution.
 Marketing.
 Grading and quality control.
 Pest control.
 Packaging.
 Communication among all concerned.
 Information, demonstration and advisory systems.
 Manufacture and supply of essential equipment and machinery.
 Financial control.
 Price stabilization
 Management and integration of the total system.
PRINCIPLES OF FISH PRESERVATION AND PROCESSING
 In some islands, more fish is caught at times than can be consumed.
 Methods are used in keeping the surplus fish in good condition for
later consumption.
 Again, fishermen sometimes cannot return to their villages promptly
with fresh fish they have caught, and it will be of value to them to
know how to preserve their catch by simple means.
FISH PRESERVATION
 Preservation of fish is done to prevent spoilage.
 Since fish is very perishable, it is therefore, necessary to
preserve fish if not consumed or disposed immediately.
 Fish preservation is the method of extending the shelf life of
fish and other fishery products by applying the principles of
chemistry, engineering and other branches of science in
order to improve the quality of the products.
Some of the important reasons for preserving foods are:

 To take care of the excess produce.
 Reaches areas where the food item is not available
 Makes transportation and storage of foods easier
 Preserving Foods at Home
Foods can be preserved at home by the following methods-
 Dehydration
 Lowering temperature
 Increasing temperature
 Using preservatives
PROPER STEPS IN HANDLING FRESH FISH
 Avoid exposing the fish to sunlight. Keep them in a shaded area.
 Ice the fish immediately after they are caught to lower their
temperature.
 Remove the gills and internal organs.
 Avoid soaking the fish too long in the water after death as this easily
spoils the fish.
 Use mechanical refrigeration if there are facilities.
METHODS OF FISH PRESERVATION

Salting
 Salt is the preservative agent used to lengthen the shelf life of fish
and fishery products.
 This is used in almost all methods of preservation except in icing,
refrigeration and freezing.
 There many different kinds of salt, some being better than others for
fish curing.
 However, in islands or in outlying places there is often no choice, and
whatever is available in the way of salt has to be used, whether it is
bought in a shop, prepared on the spot, or extracted from earth
containing salt.
Wet Salting: This is the cheaper, since it requires lesser amounts of
salt.
 The principle is to keep the fish for a long time in brine.
 If the salt is coarse, it has to be ground or pounded first.
 It is then dissolved into the water by stirring with a piece of wood. To
be good, the brine must float a fish
 Dry Salting: In this method the fish is salted but the juices, slime
and brine are allowed to flow away.
 Dry salting can be done in an old canoe, or on mats, leaves, boxes,
etc. In any case, the brine formed by the fish juices and the salt must
be allowed to run away.
 Layers of fish must be separated by layers of salt
SMOKING
Any kind of fish can be smoked. There are three main methods of
smoking:
(a) Smoking and roasting;
(b) Hot smoking;
(c) Long smoking.
Smoking and Roasting:
 This is a simple method of preservation, for consumption either
directly after curing or within twelve hours.
 Re-smoking and roasting can keep the product in good condition for
a further twelve hours. Fresh unsalted fish is put over a wood or
coconut husk fire.
Hot Smoking:
 The hot smoking system can be used for immediate consumption or
to keep the fish for a maximum of 48 hours.
 Small fish can be salted first for half an hour (see wet salting).
 After salting they are put on iron spits and dried in a windy place or
in the sun for another half hour.
 It is necessary to have an oil drum to make the smoking stove.
Long Smoking:
 If fish must be kept in good condition for a long time, for instance,
two or three months or even longer, it can be done by smoking,
provided the fish is not oily.
 For this purpose, a small closed shed made of palm leaves or other
local material can be used.
Cooking
Fish can be kept for two or three days in the following way:
 Small drums (possibly oil drums) are cleaned and filled with water.
 Salt is added in the proportion of four parts water to one of salt.
FISH PROCESSING
Methods of fish processing
a. Curing
b. Icing
c. Freezing
d. Canning
E. the use of additives or chemicals
 Fish curing is defined as the method of preserving fish by means
of salting, drying, smoking and pickling.
 Fish to be cured are usually first cleaned, scaled, and eviscerated.
 Medium-sized fishes are split through the backbone and top of
the head, with the two halves joined by the belly skin, butterfly
style.
Fish canning: - is a process involving heat treatment of fish in sealed
containers made of tin plates, aluminum cans or glass, until the product
has been fully sterilized.
The canned food fish is also prevented from contamination by
pathogenic organisms by storing them in a virtually airtight package. If
heat treatment is properly carried out canned fish may remain in
storage for several years without refrigeration.
FACTORS THAT AFFECT FISH SPOILAGE AND DETERIORATION OF FISH
FISH SPOILAGE
Spoilage is the result of a series of changes brought about in the dead
fish mainly due to enzyme and bacterial action. It starts in the fish as
soon as the fish dies when caught. In areas where temperature is high,
fish spoil within hours depending on the specie and the method of
capture.
Fish is extremely perishable. It spoils easily. “Spoilage” can be defined
as a change in fish or fish products that renders them less acceptable,
unacceptable or unsafe for human consumption. Fish undergoing
spoilage has one or more of the following signs: slime formation;
discolouration; changes in texture; off-odours; off-flavours and gas
production.
Microbiological spoilage
Live fish is normally considered to be sterile, but microorganisms are
found on all the outer surfaces (skin and gills) and in the alimentary
tract of live and newly caught fish in varying numbers. A normal range
of cfu (colony forming units)/cm2 on the skin and between 103 and 109
cfu/g in the gills and intestines has been observed.
Chemical oxidation
Chemical spoilage processes are changes taking place in the lipid
fraction of the fish. Lipids are oxidized to peroxides, aldehydes, ketones
and lower aliphatic acids. The hydro-peroxides are tasteless but can
cause brown and yellow discolouration of the fish tissue.
Autolytic spoilage
As fish dies, its enzymatic activity doesn’t stop immediately but
continues resulting in proteolytic changes that are responsible for early
quality loss in fresh fish. The more these enzymes get in contact with
the fish’s flesh the greater the spoilage. Adenosine triphosphate (ATP)
is broken down through a series of products such as adenosine
diphosphate (ADP), inosine monophosphate (IMP), inosine and
hypoxanthine (HX).
FACTORS THAT INFLUENCE THE RATE OF FISH SPOILAGE
Effects of time/temperature conditions on microbial growth. The most
crucial factors determining the quality of fishery products are time and
temperature tolerance. Proliferation of microorganisms requires
appropriate high temperatures, while at lower temperatures close to
0ºC, their activity is reduced, thereby extending the shelf life of fish
products.
Effects of hygiene on fish quality during handling: Apart from
the microorganisms that fishes have at the time of capture, more is
added via unhygienic practices and contaminated equipment such as
storage facilities.
Rough handling
Rough handling will result in a faster spoilage rate. This is due
to the physical damage to the fish, resulting in easy access for
enzymes and spoilage bacteria. Physical mishandling in the net,
such as very large catches, fishermen stepping on fish or
throwing boxes, containers and other items on top of the fish,
may cause bruises and rupture of blood vessels.
Initial bacterial load
The microflora on tropical fish often carries a slightly higher load of
Gram-positives and enteric bacteria but otherwise is similar to the flora
on temperate-water fish. Basically, bacteria populations on temperate
fish are predominantly psychrotrophic reflecting water temperatures of
about 10оC while fish from the tropics have largely mesophilic bacteria.
Methods of capture
The fishing gear and method employed determines the time taken
between capture and death. Fish caught in gillnets struggle much to
escape, and in so doing, they are bruised by the net which increases
exposure to microbial entry and subsequent deterioration.
Fish caught by hook and line methods, on the other hand, die relatively
quickly and therefore bruises and stresses are likely to be minimal.
Mode of storage
In bulk-storage, the weight of the pile may crush the fish at the bottom,
leading to a loss of weight (yield) as well as other physical damage. It
has been reported that when haddock is kept in a short, deep pile of
about 3 ft, the bottom fish lose 15% of their weight compared to a
normal weight loss of 3-8%, which is entirely due to biochemical
changes that cause a loss of water holding capacity leading to drip.
References:
 https://www.researchgate.net/publication/318225764_Fish_post-
harvest_technologies_as_a_mean_of_food_an_d_nutrition_secur
ity/link/595df81f0f7e9b1a07524fcf/download
 file:///C:/Users/Al-Saif-
Computer/Downloads/FoodSecurtityIJFSA.pdf
 https://slideplayer.com/slide/10632979/
 file:///C:/Users/Al-Saif-
Computer/Downloads/whatispostharvesttechnology-
181006081956.pdf
 https://slideplayer.com/slide/5705791/

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SARDAR BAHADUR KHAN WOMEN UNIVERSITY (SBK)

ASSIGNMENT: POST HARVESTING TECHNOLOGY

Reasons for Losses:

Causes of food deterioration:

Factors affecting post-harvest losses:

 Harvesting and threshing

Other components of the system include.

Some of the important reasons for preserving foods are:

METHODS OF FISH PRESERVATION

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