physiology

1. Ethylene & Fruits

2. Ethylene:
• It is a gaseous hormone which stimulates transverse or isodiametric
growth but retards the longitudinal one.
• Cousins (1910) found that ripe oranges produced a volatile substance
that hastened ripening of unripe bananas nearby.
• Ethylene was recognized as a plant hormone by Crocker (1935).
• Ethylene is produced in plants from the amino acid methionine. It is
formed in almost all plant parts— roots, leaves, flowers, fruits, seeds.

3. Function:
1) Growth
2) Gravity
3) Senescence
4) Abscission
5) Apical Dominance
6) Breaking of Dormancy
7) Abscisic Acid
8) Root Initiation
9) Flowering
10)Fruit Ripening

4. Uses:
Fruit Ripening
Feminising Effect
Sprouting of Storage Organs
Thinning

5. Biosynthesis:

6. Fruits:
• A true fruit or eucarp is a mature or ripened ovary, developed after
fertilization e.g. Mango, Maize, Grape etc.
• Ethylene is responsible for the ripening of fruits.
• Ethylene is responsible for the changes in texture, softening, color, and
other processes involved in ripening.

7. Ripening:
• Ripening is a process in fruits that makes it acceptable for
consumption. The fruit becomes sweeter, and softer.
• During ripening starch is converted to sugar.
• The fruit is said to be ripe when it attains its full flavor and aroma
(watada et al ., 1984).
• Ripening causes colour change in the fruit.
• Based on ripening behaviour, fruits are classified as:
– Climacteric
– Non Climacteric

8. Climacteric Fruits:
• Fruits show dramatic increase in the rate of respiration during ripening
and well respond to ethylene for ripening.
• e.g. Apple, Banana, Mango, Tomato.

9. Non -Climacteric Fruits:
• Fruits do not show dramatic increase in the rate of Respiration during
ripening and do not respond to Ethylene for ripening
• e.g. Citrus, Grapes, Pineapple & Watermelon.

11. Changes during ripening:
1) Cell wall
2) Starch
3) Organic acids
4) Pigments
5) Flavoring compounds
6) Ascorbic acid
7) Phenolic
8) Amino acids and proteins
9) Respiration
10)Transpiration
11)Ethylene evolution rate

12. Current Ripening Methods:
• Calcium Carbide is widely using chemical to ripening.
• It contain traces of arsenic and phosphorus, these are toxic and may be
hazardous to health.
• Calcium Carbide reacts with moisture in the air to produce acetylene
gas.
• Acetylene gas acts as a ripening agent, but is believed to affect the
nervous system by reducing supply of oxygen to the brain.
• It is banned under Rule 44-AA of PFA (Prevention of Food
Adulteration) Rules, 1955.

13. Ripening with Artificial Ethylene:
• Scientific and safe ripening method accepted world wide.
• Ethylene is a natural plant hormone that the fruit itself emits as it
ripens.
• Ethrelor ethaphon (2-chloroethane phosphonic acid).
• Exposure of unripe fruit to a miniscule dose of ethylene is sufficient to
stimulate the natural ripening process until the fruit itself starts
producing ethylene in large quantities.
• The use ethylene to promote ripening is permitted under FDA
regulation 120,1016.

15. The four major factors for commercial
ripening:
• Temperature control.
• Ethylene gas.
• Adequate air circulation

16. Undesirable Ethylene Effects:
• Undesired ripening and softening of fruits in storage.
• Accelerated senescence and loss of green color in immature fruit.
• Sprouting (stimulation or retardation).

17. Overcoming Ethylene’s undesirable
effects:
• Eliminating sources of ethylene
• Ventilation
• Chemical removal

18. THANKS