concepts of post harvest physiology

1. Institute seminar
on
“CONCEPTS OF POSTHARVEST MANAGEMENT OF
FRUITS AND VEGETABLES ”
Presented By
Dr. Asha Kumari
Scientist (Plant Physiology)

2. CONTENTS
Physiology and Biochemistry of Ripening of
Fruits
Ethylene evolution and Ethylene management
Factors leading to Post-Harvest Losses
Management of Post-Harvest Losses

3. Physiology and Biochemistry of Fruit
Ripening
Ripening: It indicates the sequence of change in
texture, colour, flavour which leads to a state at
which the fruit become acceptable to eat.(Sudheer et
al.,2007)

4. Types of Fruits
• According to ripening behaviour:
1. Climacteric – Those fruits that get ripened after
harvesting. It produces more ethylene and have higher
cellular respiration. Eg. Mango,Banana,Apple,Kiwi,
Peach, Pear, Plum, Tomato
2. Non climacteric- Those fruit that not ripened after
harvesting. It produce less ethylene and have lower
respiration than climacteric fruit. Eg. Citrus, grapes,
Summer squash, Pepper

5. Growth, respiration and ethylene production
in climacteric and non climacteric fruit

6. Changes occurs During Ripening

7. Changes during Ripening of Fruits
A. Physical changes
 Softening: Hydrolysis of starch to simple sugar
 Colour: Chlorophyll decrease and increase in
lycopene, anthocyanin, carotenes and xanthophyll.
Loss in weight
B. Physiological changes
 Respiration rate
 Ethylene evolution rate

8. C. Chemical changes
Flavouring compounds
1. Flavour is subtle and complex perception that
combined taste, smell and mouth feel .
2.Decrease in acidity with increase in sugar .
Aroma :Aroma of ripe fruits is due to the production
of volatile compounds like esters, aldehydes, alcohols,
ketones and terpenoids etc.
Organic acids : Acidity of fruits decrease during
ripening of fruits. Increase in sugar during ripening
.

9. Carbohydrates
 Hydrolysis of starch to simple sugars this changes
depends upon temperature and physiological state of
fruits.
Phenolic compounds
 Astringency is directly related to phenolic
compounds.
 Astringency decrease with fruit ripening because of
conversion of phenolic compounds soluble to
insoluble.

10. ETHYLENE
• Ethylene is a gaseous plant hormone with a
characteristics suffocating, sweetish odour,
colourless hydrocarbon gas with a faint.
• Properties: Molecular wt. – 28.05
• Boiling point : -103.7°C (at 760 mm Hg)
• Freezing point: -169.2°C
• Flammable limit in air 3.1 to 32 % by volume
• Source of Ethylene: Ripened fruits, Explosion proof
ethylene mixture: Ethephon (ethrel, CEPA, florel)
Calcium carbide , Ethylene generators

11. ETHYLENE BIOSYNTHESIS

12. Undesirable effect of Ethylene and
how to regulate it?
• Ethylene have different uses like in ripening, Sex
expression, Flower bud development,. But it has
undesirable effect also like Sprouting of potatoes,
Susceptibility to plant pathogens, Accelerated
Senescence Causes abscission of leaves under
drought condition, etc. To overcome this different
ways are there:
A. Removal of ethylene
1. Eliminating source of ethylene. Eg. Over ripe fruits.
2. Ventilation
3. Chemical removal : Potassium per magnate ,

13. Ultraviolet lamps- produce ozone, TiO2, Activated or brominated
charcoal , Catalytic oxidizing
4.Bacterial system
5. Hypobaric storage.
B. Inhibiting the effect of ethylene
1. Controlled atmosphere
2. Specific anti-ethylene compounds. Eg. 1-MCP, STS
3. Inhibition ethylene biosynthesis. By. AOA, AVG
C. Molecular manipulation of ethylene response. e.g.. FLAVR
SAVR transgenic variety, nir, nor, rin genes in tomato.

14. In apple genetic engineering approved varieties-Arctic
Granny and Arctic Golden
 Suppression of ACC synthase gene expression,
Insertion of SAM hydrolase gene,
Suppression of ACC oxidase gene expression (Revathy,N
 ,et al.,2012, Wills,et al.)

15. Factors leading to Post Harvest Losses
 Pre harvest factors
 Harvest factors
 Post harvest factors
• Pack house factors
• Packing factors
• Storage factors
• Transportation factors

16. Pre harvest factors includes:
 Improper planning (growing cultivars that mature when
market prices are lowest)
 Nutrients :Excessive application of nitrogen
 Inappropriate irrigation (too close to harvest date)
 Lack of pest and disease management
Harvest Factors includes:
Harvesting at wrong maturity stage
Wrong technique of harvesting
Harvesting during hot hours of the day
Over-packing of field containers

17. Post Harvest factors includes:
Lack of cleaning/washing
Misuse of postharvest treatments (hot water dips/over
waxing/inadequate chlorine in water etc.)
Lack of adequate cold storage
 Lack of efforts to maintain high relative humidity
Over loading of cold stores

18. Management of Post Harvest Losses
• Different methods are used for managing Post
Harvest Losses:
Pre-cooling: Removing the field heat of the
harvested produce immediately after harvesting to
increase keeping quality of produce and it is done to
retard ripening and senescence process of produce.
Pre-cooling done within 24 hrs after harvesting of
produce.

19. Types of Pre-cooling
 Cold air
• Room cooling
• Forced air cooling
i. Tunnel type
ii. Cold wall
iii. Serpentine cooling
iv. Container venting
v. Cooling in transport
 Cold water or hydro cooling: Chlorine, iodine, nutrient, growth
regulators, fungicides can be added in water to sanitize/improved
nutrient status
 Top icing (Leafy Vegetables)
 Evaporation of water from produce • Evaporative cooling • Vacuum
cooling
 Hydrovac cooling (Thompson,F, et al.,2000., Saraswati,L, Revathy,
N,et al.,2012)

20. Pre-Cooling Methods
Principles Cooling Methods Examples
Convection Room cooling All fruits and
vegetables
Pressure Cooling Forced air cooling Fruits and fruits
type vegetables
Conduction Hydro cooling Stem , greens and

21. THANKS FOR LISTENING…