CHILLING

1. CHAPTER 3
Chilling
1. Fundamentals of Chilling
2. Methods of Chilling
3. Methods of Storing Iced Fish
4. Types of Containers
5. Types of Insulation
6. Chilling on Board
7. Quality Changes of Fish During Chilling
8. Handling Chilled Fish

2. • Fish is highly perishable- proper handling must
start from the moment it is harvested until it
reaches the consumer’s table.
• Lowering the temperature (chilling,
refrigeration and freezing)is the key factor in
maintaining the quality of fresh fish
• Chilling is the most common practice in
keeping the freshness of fish.

3. Methods of Preserving/Processing
Fish
Temperature Control
Use of Packaging technologies
Other Processing Methods
Use of Additives
Removal of Moisture

4. Chilling
-means the reduction of temperature to some
point below (-1.1 to -2.2⁰C) or above (0⁰C) the
freezing point of the fish muscle.
 Chilling does not stop spoilage but slow it
down considerably.

5. Methods of chilling
1. Wet Ice (Icing)
2. Chilled Seawater Ice
3. Other Methods

6. • WET ICE (ICING) - Icing is by far the most
common and useful way of chilling the fish
catch.
• Cooling is effected by the direct contact
between the melted ice and the fish.
• When ice is place in close contact with the
fish, heat is transferred from the warm
fish to the ice resulting to the melting of
ice; in turn the fish is cooled down by the
melted ice.
Methods of Chilling

7. WET ICING (ICING)
• Direct contact between melted ice and fish
• ICE- an ideal cooling media; with very large
cooling capacity
• -harmless, comparatively cheap, can quickly
cool
• -occurs I different forms: crushed, tube,
flaked, blocks

8. Factors to be considered when icing
1. Sufficient ice must be used to maintain fish
temperature at 0 ⁰C.
• For longer trips more ice than fish is needed , more than the
usual 1: 1 ice ; fish ratio,
2. The arrangement of ice and fish must be in such
a way that accumulated water, blood and slime can
be drained easily.
3. Ice and fish should be placed alternately to avoid
localized heating. Fish must be sufficiently surround
with ice on the sides, top and bottom

9. 4. When packing mixed fish, big fish must be
placed at the bottom and small fish on top.
• Fish with delicate skin should be packed on top of fish
with scales.
5. Gutted fish must be filled up with ice in the
belly cavity
• must be arranged with belly down in a slanting position
inside the container.

10. - This is also termed as “slush ice ”which is a mixture of
seawater and crushed ice used for chilling of fish catch.
- The amount of ice depends on the initial temperature
of the water and the fish, size of the container and the
quality of its insulation, and the length of the trip.
 The advantages of CSW over icing are:
1. CSW chills fish much faster than wet ice.
2. Fish is CSW do not suffer from physical damage due
to crushing or pressure from other fish.
3. Fish in CSW are washed in the slurry.
4. CSW chilled fish do not necessarily keep longer than
wet iced fish.
2. Chilled Seawater Icing

11. – a mixture of seawater and crushed ice
Advantages:
*CSW chills fish much faster than wet ice
*Fish do not suffer from physical damage
due to crushing of pressure from the other
fish
Disadvantages:
* Do not necessarily keep longer than wet
ice
2. Chilled Seawater Icing

12. A. Refrigerated Air:
 commonly done in big commercial boats.
 chilled air is circulated by a finned evaporator and fan
B. Gel Ice Mat
 Freezing water-based gel
 Suitable for air transport
No water leakage during thawing
Other methods:

13. 3. Dry ice
o Dry ice is sold carbon dioxide. Cooling is effected
by the evaporation of the dry ice.
o Due to its very low temperature (78.9C), dry iced
should not be used in direct contact with fish to
avoid cold bums.
o This method of chilling is preferred for air
shipment of fish as this does not cause leakage.
o However, the use of dry ice is subject to
restrictions because it expands from a solid form
into a gas and may be expel oxygen, posing a
hazard to the safety of airplanes.

14. Types of Ice:
Block Ice
Crushed Ice
Flake Ice
Tube Ice
Rarely used directly for cooling
Irregular size, sharp edges, can
physically damage fish
commonly produced from FW as
thin flakes, formed instantly on cold
metallic surfaces
Lasts longer, melts more evenly,
useful for transporting fish in
uninsulated containers

16. Methods of storing iced fish:
SHELFING
BOXINNG
BULKING

17. BULKING
• Fish are layered to achieve intimate contact
Advantages
Disadvantages
Economize
space; utilized
in the hold of
fishing boats
When a very
large volume of
fish needs to be
stored

18. • Fish is stored in a single layers, gut cavity
down on a bed of ice; a little ice is spread on
top (to ensure bleeding through the cut
surface; retard spoilage)
• applicable to large which are
• fish can be separated into different catches
Shelving

19. Boxing
• The preferred method of storing iced in fish
• Fish and ice are layered in specially made boxes
Advantages
Disadvantages
Easy segregation of
first caught, small
from large, etc.
Minimum handling
and with good
boxing practice, fish
will not damaged
physically
Space occupied
in storage is
greater than
that for bulking

21. Types of Containers:
• insulating properties
• proper shape and dimension for the fishery
product concerned
• easily to handle, fill and empty
• easy to clean and stack securely one on top to
another
• constucted from non poisonous materials
• adequated provision for drainage of melt-

22. Types of containers:
1. Plastic Boxes
2. Galvanized Iron Sheets Tubs
3. Wooden Boxes
4. Coconut, Bamboo, or Rattan Baskets

23. • *High density polythylen (HDPE) and
polypropylene are widely use in the
manufacture of modern day containers.
• Polyethylene:
• Polyethylene(PE) is made by subjecting
gaseous ethylene monomer to heat and
pressure in the presence of a metalic catalyst.
• PE is classified into low density (0.910 to
0.925 g/cm medium density (0.926 to 0.940
g/cm and high density
TYPES OF Plastic Boxes

24. • *high density polyethylene is divided into type III
(density0.941 to 0.959 g/cm, and type IV which
has a density of 0.960 g/cm and above

25. Polypropylene (PP)
- Is a homo-polymer of propylene. It has low
density (around 0.902 g/cm and superior
processability.
It is one of the lightest plastics, has a good resistant
to grease and most chemicals, provides a good
barrier to water vapor and can withstand high
temperatures due to its high softening point.
Polypropylene is more rigid, stronger and lighter
than polyethylene
Polystyrene (Styrophore)

27.  Tubs made from GI sheets (Baiiera) are conical in shape and
so far the most commonly used container by fishers in the
Philippines.
These tubs are not provided with drains; they easily corrode
they have poor insulating property and are quite difficult to
handle due to their fill capacity, around 40-50 kg.
 Baheras are becoming less popular locally and are slowly
being replaced by polystyrene boxes.
Wooden Boxes:
 Wooden boxes can withstand rough handling and have
relatively good insulating property
 However, they are not easy to clean, and are slightly difficult to handle
because of their weight
 They become a hazard to handlers ( splinters can cause injury) when
they are not properly maintained
Galvanized Iron (GI Sheet Tubs (Baftera)

28. Pointers in Handling Chilled Fish
The choice of insulating material will
depend on its thermal conductivity or resistance
and permeability to water vapor (waterproof),
density and compressive strength.

29. • The following must be taken into
consideration when handling chilled fish:
1. Temperature
2. Time
3. Contamination
4. Damage