Fruit Ripening _Second Year + Third Year PDF.pdf

July 23, 2025 [DR. SHARAD BISEN, HORTICULTURE]
1 Raja Bhoj College of Agriculture, Balaghat, JNKVV, Jablapur
Lecture : Fruit Ripening - Processes, Technologies, and Practices
1. Introduction to Fruit Ripening
Ripening is a physiological process through which fruits achieve their
optimal flavor, color, texture, and palatability. This process involves significant
biochemical changes, such as the conversion of starch to sugar, which
enhances sweetness and edibility. Fruits are categorized into two groups
based on their ripening behaviour: Climacteric and Non-Climacteric.
2. Classification of Fruits Based on Ripening Behaviour
2.1 Climacteric Fruits
• Definition: Climacteric fruits continue to ripen after harvest, entering a
"climacteric phase" characterized by increased respiration and ethylene
production.
• Characteristics:
• Emit ethylene gas, a natural ripening hormone, during ripening.
• Soft and delicate when fully ripe, making them prone to damage
during transportation.
• Harvested mature but hard and green, then ripened near
consumption areas using controlled ethylene exposure.
• Examples:
• Mango, Banana, Papaya
• Guava, Sapota, Kiwi
• Fig, Apple, Passion Fruit
• Apricot, Plum, Pear
• Handling:
• Due to their delicate nature when ripe, climacteric fruits are best
ripened close to the point of consumption to minimize damage
during transport.

2.2 Non-Climacteric Fruits
• Definition: Non-climacteric fruits do not ripen further after harvest.
• Characteristics:
• Produce minimal ethylene and do not respond significantly to
ethylene treatment.
• No marked increase in respiration or carbon dioxide production
during storage.
• Examples:
• Orange, Mousambi, Kinnow
• Grapefruit, Grapes, Pomegranate
• Litchi, Watermelon, Cherry
• Raspberry, Blackberry, Strawberry
• Carambola, Rambutan, Cashew
• Degreening:
• For citrus fruits (e.g., orange, lemon, mousambi, kinnow), ethylene is
used as a de-greening agent to break down green chlorophyll in the
peel, revealing yellow or orange carotenoid pigments for better
market appeal.
2. Importance of Ripening Technologies
Uniform and rapid ripening is a challenge in the fruit industry. Various
traditional and modern methods are employed to ensure proper ripening,
each with its advantages and limitations. The ripening duration varies by fruit
type and environmental conditions (e.g., 5–6 days for mangoes, 6–7 days for
sapotas).

4. Ripening Methods and Technologies
4.1 Traditional Methods
• Household Method:
• Process: Place unripe fruits with ripe fruits in an airtight container.
Ethylene released by ripe fruits accelerates ripening.
• Example: Mangoes ripened in an airtight rice bin.
• Advantages: Simple and cost-effective.
• Limitations: May result in uneven ripening.
• Smoke-Induced Ripening:
• Process: Fruits are placed in an airtight room, and smoke (producing
acetylene gas) is used to induce ripening.
• Example: Commonly used for bananas and mangoes.
• Limitations:
• Uneven color and flavor development.
• Residual smoke odor affects fruit quality.
• Paddy Husk/Wheat Straw Method:
• Process: Unripe fruits are layered over paddy husk or wheat straw for
about a week to ripen.
• Example: Mango ripening using paddy straw.
• Advantages: Natural and low-cost.
• Limitations: Slow and inconsistent ripening.

4.2 Chemical Methods
• Ethrel Dip:
• Process: Dip unripe mature fruits in a 0.1% ethrel solution (1 ml
ethrel in 1 liter of water), wipe dry, spread on newspaper without
touching, and cover with a thin cotton cloth.
• Duration: Ripening occurs within 2 days.
• Advantages: Fast and effective.
• Limitations: Requires careful handling and drying.
• Ethrel Solution in Ripening Chamber:
• Process: Mix 10 ml ethrel and 2 g sodium hydroxide in 5 liters of
water in a wide-mouthed vessel placed inside an airtight ripening
chamber. About one-third of the chamber is filled with fruits, leaving
space for air circulation.
• Duration: Ripening occurs in 12–24 hours.
• Advantages: Cost-effective and faster than traditional methods.
• Additional Tip: Including ethylene-releasing fruits (e.g., papaya,
banana) in the chamber can reduce chemical costs.
• Ethylene Gas in Pressurized Cans:
• Process: Ethylene gas from pressurized cans is used to ripen fruits in
24–48 hours.
• Example: Uniform ripening of papaya using ethylene gas.
• Advantages: Precise and controlled ripening.
• Limitations: Requires specialized equipment.

4.3 Safest Method: Ethylene Gas
• Why Preferred: Ethylene is a natural ripening hormone, safe for consumers,
and effective under controlled conditions of temperature and humidity.
• Benefits:
• Enhances fruit appearance (e.g., turns banana peels from green to
yellow).
• Maintains sweetness and aroma, improving market appeal.
• Stimulates natural ripening until the fruit produces its own ethylene.
5. Methods of Applying Ethylene
The method chosen depends on cost, convenience, and safety
considerations. Pure ethylene is explosive at concentrations above 3%, so diluted
ethylene gas mixtures are safer.
5.1 Optimal Conditions for Ethylene Application
• Temperature: 18–25°C (29–31°C for mangoes).
• Relative Humidity: 90–95%.
• Ethylene Concentration: 10–100 ppm (varies by fruit).
• Duration: 24–74 hours, depending on fruit type and maturity stage.
• Air Circulation: Ensures uniform ethylene distribution.
• Ventilation: Prevents carbon dioxide buildup (>1%), which can retard
ripening.

5.2 Application Methods
• Trickle Method:
• Ethylene gas is trickled into the ripening room to maintain a
concentration of 10 µl/L for 24 hours.
• Requires continuous monitoring and ventilation to prevent CO₂
buildup.
• Shot Method:
• A single initial charge of ethylene (20–200 µl/L) is introduced,
followed by ventilation after 24 hours.
• Suitable for poorly sealed rooms with vented cartons and forced air
circulation.
5.3 Optimal Ripening Conditions for Specific Fruits
Fruit
Ethylene Conc.
(ppm)
Exposure Time
(hr)
Ripening Temp.
(°C)
Storage Temp.
(°C)
Avocado 10–100 12–48 15–18 4.4–13
Banana 100–150 24 15–18 13–14
Honeydew Melon 100–150 18–24 20–25 7–10
Kiwifruit 10–100 12–24 0–20 0.5–0
Mango 100–150 12–24 20–22 13–14
Orange
(Degreening)
1–10 24–72 20–22 5–9
Stone Fruit 10–100 12–72 13–25 -0.5–0

6. Ripening Chambers
• Design:
• Airtight rooms with controlled temperature and humidity.
• High ceilings allow stacking of fruit boxes (at least four high).
• False ceilings ensure adequate air circulation.
• Equipment:
• Small fans for uniform ethylene flow.
• Catalytic generators for safe ethylene production (e.g., passing
ethanol over activated alumina).
• Ethephon:
• Used as a spray for tomatoes destined for processing.
• Ethylene release increases with higher pH and humidity.
7. Degreening of Citrus Fruits
• Purpose: Removes green chlorophyll from the peel to reveal yellow/orange
carotenoid pigments, enhancing market appeal.
• Challenges:
• In tropical regions, citrus fruits often remain green despite maturity
due to high temperatures (above 25°C) that prevent chlorophyll
breakdown.

• Process:
• Conducted in ripening rooms with ethylene concentrations of 1–10
ppm for 2–3 days.
• Optimal temperatures: 25–30°C for rapid degreening, 15–25°C for
best color development.
• Daily ventilation prevents CO₂ buildup (>1%).
8. Challenges and Considerations
• Health and Safety:
• Calcium carbide is hazardous and banned due to toxic residues
(arsenic, phosphorus).
• Ethylene is the only safe and globally accepted ripening agent.
• Uniformity: Traditional methods often result in uneven ripening, affecting
quality and marketability.
• Cost and Accessibility: Modern methods like ethylene gas require
investment in equipment and controlled environments, which may be
challenging for small-scale farmers.

Fruit Ripening _Second Year + Third Year PDF.pdf

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Fruit Ripening _Second Year + Third Year PDF.pdf