Evolution of storage from traditional ways to modern ways and objectives of storage.

1. STORAGE OF POST HARVESTED
FRUITS AND VEGETABLES
By
M. Vigneshwaran,
III- B. Voc. Food
Processing,
The Gandhigram Rural
Institute(DU),
Gandhigram , Dindigul

2. Reduce rate of
respiration and
transpiration
Inactivation of
enzymes by lower
temperature,
chemical , etc
Manipulation of
gaseous environment
surrounding fruits
and vegetables
Delaying ripening
and senescence by
lowering down
temperature
Reduce Undesirable
biochemical and
physiological
activities
Objectives
of
storage

3. Traditional storage
Modern storage/
Improved storage
Methods of Storage
1. Storage in pits
2. On site storage
3. High altitude
cooling
4. Clamp storage
5. Cellars or
underground storage
6. Wind breaks
7. Barns
8. Night ventilation
9. Evaporative cool
storage
1. Refrigerated stores
2. Ice bank coolers
3. Modified atmospheric
storage
1. Active
2. Passive
1. Controlled
atmosphere
storage
2. Silicon
membrane
technology
3. Vacuum
packaging

4. Traditional storages:
• Storage in pits:
usually done in highland ( area with high
rainfall)

5. • On site storage:
In Situ means delaying the harvest until the
crop is required and is employed for the root,
tuber and rhizomes crops. Crops should be left
in the soil until preparation for the market.
Disadvantages: In case of cassava, delayed
harvest results in reduced acceptability and
starch content and pre harvest losses. The crops
should be protected from pest and disease
attack, chilling and freezing injuries.

6. • High altitude cooling:
Advantage of storing perishable commodities.
Higher
Altitude
Land t°C
t4=t3 – 10 °C
t3= t2 – 10
°C
t2= t1 – 10
°C
t1= t – 10 °C
1 km
1 km
1 km
1 km

7. • Clamp storage:
Potatoes for processing are best kept at
intermediate temperatures to limit the
production of sugars which darken when heated
during processing. Potatoes meant for
consumption must also be stored in the dark,
since the tubers will produce chlorophyll
(turning green) and develop the toxic alkaloid
solanine if kept in the light. Potatoes stored
for use as seed are best stored in diffused
light.

8. • Cellars / underground stores:
Usually stored at the bottom of the mountains or
hills
E.g.: apples, cabbage, potatoes during winter

9. • Wind breaks:
It is built on wooden stakes which is driven down into
the ground and are about 2m height from the ground,
sloped towards outside. In this type of structures, the
onions can be stored even up to six months.

10. • Barns:
It is a simple storage structure prepared by farmers for
storage of bulbous root crops. Here the crops are placed
in platforms up to a maximum depth of 1 meter inside a
structure. The structure allows free circulation of air
and provides protection against rain and direct sunrays.

11. • Night ventilation:
It takes advantage of the natural airflow around
the product to remove heat and humidity
generated by respiration. Buildings providing
some form of protection from the external
environment and with gaps for ventilation can be
used.
Night temperature – day temperature = very high.
Storage structure consists of insulated
materials
Ventilators at the bottom and fans at the top.

12. • Evaporative cool store:
The principle of evaporation can be used to cool
stores by first passing the air into the store
through a pad of water. The degree of cooling
depends on the original humidity of the air and
the efficiency of evaporating surface.

13. Improved storage methods /
Modern storage method
• Refrigerated stores:
Tropical and sub-tropical fruits have more post
harvest loss because with the increase of
temperature, the rate of respiration increases
leading to decrease in the storage life.
Moreover, there is also increase in the rate of
transpiration leading to rapid moisture loss and
shrinkage.

14. • Ice bank coolers:
Here the ice cool air is positively directed through the
boxes containing fresh fruit. This helps in removal of
larger amount of heat in a short period of time from the
commodities. The system maintains a temperature of 0.5-
0.80C and relative humidity of 98% once the initial
cooling is achieved.
Box with fruits
Ice cool
air

15. • Modified atmosphere storage/packaging:
The air inside the container is modified than normal to improve shelf
life.
Active Passive
Additiv
es O2
CO2
Head space
consists of
CO2
absorbents/
emitters,
oxygen
absorbents/
ethylene
absorbent

16. • Controlled atmospheric storage:
The storage of fruits and vegetables in
CA Storage is one of the most advanced methods
of storage.
From the construction point of view, controlled
atmosphere facilities are similar to
refrigeration facilities. However, they should
be airtight to allow creation of an atmosphere
different from normal. The Oxygen consumption
and its replacement by carbon dioxide by
respiration, create the atmosphere. When the
appropriate combination has been reached, a
limited intake of oxygen is required to satisfy
the reduced rate of respiration. Accumulation of
carbon dioxide is removed by means of different
methods.

17. Difference between CA AND MA:

18. • Silicon membrane technology:
It is a new technology and is gaining popularity as it
is energy efficient, less expensive and is a simple
passive method. The membranes are polymers which has the
ability to allow certain gases to pass through it at
different rates based on their physical and chemical
properties. The selective permeability of gases combined
with the respiration activity of the stored commodities
leads to increase in the CO2 and decrease in the O2 level
in the chamber, hence the respiration rate slows down.

19. • Vacuum packaging:
Here the produce is packed in films of low oxygen
permeability. The air is drawn out of the package and
the pressure inside the package is much lower than the
atmosphere and the film collapse round the produce. The
oxygen level inside the package is less than 1%.

20. • Hypobaric storage:
Fruits can be stored under low pressure of 0.2 –
0.5 atmospheric pressure and temperature of 15 -
240C under airtight chamber. Pressure is reduced
by sucking air and creating vacuum.
Mechanism
Reduced O2 supply slows down the respiration. When
pressure reduced from the 1 atm to 0.1atm the
effective O2 concentration reduced from 21 to
2.1%.
• E.g. in apples, low pressure reduces level of
ethylene to 0.01ppm which does not stimulate
ripening.
• Released ethylene is removed out of storage.
• Volatiles such as CO2, acetaldehyde, acetic acid,

21. Thankyou