Cooling and Freezing`

1. PRESERVATION BY LOW TEMPERATURE
REFRIGERATION
MUNNA IYPE JOY
BTF-11-222
IICPT

2. REFRIGERATION
● One of the first application of mechanical refri.
Was to preserve food
Refrigerated storage
Cool Storage Frozen storage

3. COOL STORAGE
Sources of spoilage in a harvested product –
●autolysis
● microbes
● rodents,
● worms,
● mechanical damage.
● Refri. Doesnt make any irreversible changes.
● Slows down all kind of spoilage processes.

4. REFRIGERATED GAS STORAGE
● In addition to low temp., Gas composition
control (CO2 and O2).
● It increases shelf life.
● If CO2 level goes beyond critical limit, internal
physiological breakdown leading to rotting.
● Soln is wrapping the fruits with tissue paper
impregnated with colourless odouless mineral
oil.

5. Factors considered
I.Control of humidity
II.Control of ethylene
III.Control of chilling injury
IV.Temperature

6. I. Control of humidity
● Uses direct expansion system
● Refrigerand inside coils expands by
absorbing temperature from product.
● Temp. Gradient causes water loss.
● Indirect expansion is preferred.
● Control of RH is important for long term
storage of commodities.

7. II. Control of ethylene
● Ethylene is a plant hormone which induces
ripening and senescence.
● Ripended fruit emits more ethylene.
● Hence it should not be stored with unripen fruits
which are sensitive to ethylene.
● Usually ventillation is provided in order to
remove ethylene.
● If ventillation is not feasible, ethylene can be
destroyed by oxidation.

8. II. Control of ethylene contd..
● Potassium permanganate held on an inert
substrate is generally used for this pupose.
● UV light is also an industrially used alternative.
● The intermediate compounds formed during
ozone formation destroys ethylene.
● Research about catalytic converters is being
done( Platinum).

9. III. Control of chilling Injury
● Chilling injury dependent on temperature
and time of exposure to that temp.
● Early stages of chilling injury are reversible.
● Some products tolerate chilling injury
without symptoms if the time of exposure is
short.
● There are a number of methods available
to limit chilling injury.

10. III. Control of chilling Injury
contd..
These include
● Stepwise reduction in storage temp.
● Intermittent warming during storage.

11. IV. Temperature
● Temperature control helps to prevent chilling
injury
● Storage temperature varies from product to
product.
● Each 10 deg rise results in doubling of rate of
enzymatic reactions and microbial spoilage.

12. Temp & RH for some produces
PRODUCE TEMPERATURE( deg c) RELATIVE HUMIDITY
Apple -1-4 90-95
Avocado 7 85-90
Black berries -0.5-0 90-95
Grapes(American) -0.5-0 85
Jackfruit 13 85-90
Beans,dry 4-10 40-50
Broccoli 0 95-100
Carrots, mature 0 98-100
Cucumber 10-13 95
Okra 7-10 90-95

14. PART II
REASON FOR POST HARVEST
LOSSES IN INDIA

15. LOSSES ...
● About 30% of f&v grown in India gets wasted
● 40 million tonnes
● 13 million US $

16. Losses due to..
● Gap in cold chain
● Insufficient storage capacity
● Unavailability of cold storages near farms
● Poor transportation facility
● Lack of processing technology and facility

17. Sites of losses
 Harvest
 Preperation
 Preservation
 Processing
 Storage
 Transportation

18. REFERENCES
Wisemax & Lockhart, Fruits and vegetable
preservation, p 138-139
Lisa kitinoja& A. Kader, 2003, Small scale post
harvest hhandling practices: A manual for
horticultural crops, 4th edition, p 133-138
Chilukuri Maheswar, Post harvest losses due to
gaps in cold chain in India- A solution, 2006

19. Thank You