Ripening of Climacteric and Non-Climacteric Fruits: An Overview

RIPENING OF
CLIMACTERIC AND
NON CLIMACTERIC
FRUITS

RIPENING
 Ripening - ﬁnal stage of development of fruit, which
involves series of physiological and biochemical events
 Ripening induces changes that are structural, physical,
chemical, nutritional, biochemical, or enzymatic. These
changes are degradative, and synthetic.
 The changes occurring are: thickening of cell wall and
adhesion, increased permeability of plasmalemma,
changes in color, loss of texture, thickening of cuticle
etc

CLIMACTERIC VS NON-
CLIMACTERIC
Climacteric: fruits are defined as fruits that enter
‘climacteric phase’ after harvest i.e. they continue to
ripen. During the ripening process the fruits emit
ethylene along with increased rate of respiration.
These fruits are harvested hard and green, but are fully
mature and ripened near consumption areas as fully ripe
fruit are too delicate to withstand transportation over
long distances.
Small dose of ethylene is used to induce ripening process
under controlled conditions of temperature and humidity.
Climacteric fruits are:

Non-Climacteric: Non-climacteric fruits once harvested
do not ripen further. They produce very small amount of
ethylene and do not respond to ethylene treatment.
There is no characteristic increased rate of respiration
or production of carbon dioxide. Nonclimacteric, in
which respiration shows no dramatic change and
ethylene production remains at a very low level.
Non-climacteric fruits are:
Orange, Mousambi, Kinnow,
Grapefruit, Grapes, Pomegranate, Litchi, Watermelon,
Cherry, Raspberry, Blackberry, Strawberry, Carambola,
Rambutan, Cashew.

Normally, the number of days taken for edible ripening varies for different
fruits for instance, it takes about 5 to 6 days for mangoes and 6 to 7 days
for sapotas to ripen. Under natural conditions, ethylene plays a major
physiological role in the ripening process.
TECHNOLOGIES FOR
RIPENING OF FRUITS (Artificial
fruit ripening techniques)

Fruit ripening using calcium carbide
•Most climacteric fruits in India are ripened with industrial grade calcium
carbide. It contains traces of arsenic and phosphorus (are toxic and
exposure may cause severe health hazards), and, thus use of this
chemical for this purpose is illegal in most countries.
•In India too, use of calcium carbide is strictly banned as per PoFA
(Prevention of Food Adultration) Act [Section 44AA].
•Calcium carbide, once dissolved in water, produces acetylene which acts
as an artificial ripening agent. Acetylene is believed to affect the nervous
system by reducing oxygen supply to brain.
Workers at a fruit market using calcium carbide to ripen
raw mangoes

The only safe and worldwide accepted method is using ethylene, which is
a natural hormone for ripening when done under controlled temperature
and relative humidity conditions.
Ethylene being a natural hormone does not pose any health hazard for
consumers of the fruits. It is a de-greening agent, which can turn the
peel from green to perfect yellow (in the case of bananas) and maintain
the sweetness and aroma of the fruit.
METHODS OF APPLYING
ETHYLENE
Trickle method involves trickling ethylene gas into room so as to
maintain a concentration of 10 µl per litre, usually for a period of 24
hours.
 Room is then ventilated after 24 hours to prevent carbon dioxide
exceeding 1% concentration, which would retard ripening.
 Rooms that are poorly sealed are packed in vented cartons stacked on
pallets, and fruit temperature is controlled by forced air circulation as
in a cooling facility.
 A small fan can be used to ensure a uniform continuous flow of
ethylene into and through the room. Forced-air ripening provides

Ripening can also be initiated using ethylene generated by passing ethanol
over a bed of activated alumina.
•This method is safer than using pure ethylene gas.
•Ethylene releasing compounds such as ethephon (2-chloroethy1
phosphonic acid) are sometimes used to ripen tomatoes destined for
processing.
•When using ethephon as spray, amount of ethylene released will increase
as pH and/or relative humidity increase.
Commodity Ethylene
conc.(ppm)
Ethylene
exposure time
(hr.)
Ripening temp.
oC
Storage Temp
oC
Avocado 10-100 12-48 15-18 4.4-13
Banana 100-150 24 15-18 13-14
Honey dew
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

DEGREENING
In order to improve external skin colour and market acceptance, citrus like
orange, lemon, Mousambi can be treated with ethylene, as a de-greening
agent. Ethylene treatment breaks down the green chlorophyll pigment in the
exterior part of the peel and allows the yellow or orange carotenoid
pigments to be expressed.
 Degreening is carried out in ripening rooms and this process takes 2 to 3
days. It is again necessary to ventilate daily to ensure that CO2 levels do not
exceed 1%. The most rapid degreening occurs at temperatures of 25 to 30ºC
but the best colour (concentration of peel carotenoids) occurs at 15oC to
25oC.
Ripening
chambers
Catalytic generator for
ethylene production in
ripening rooms

DELAY IN RIPENING
Gibberellins:
Post harvest treatment of gibberellins markedly retards ripening of
tomatoes, guava and banana. The delay in ripening was indicated by
lowered respiratory rate, retarded climacteric and delayed colour
change.
Pre-harvest sprays of gibberellins were shown by Kitagawa to have a
striking effect in decreasing the rate of development, maturation and
ripening of lemons.
Some of the effects are firmness, delayed accumulation of
cartoenoids on ‘Navala orange’, higher TSS and Ascorbic acid in
lemons.

Auxins (CIPA and NOA) :
Pre-harvest application of CIPA and NOA at 25 ppm each delayed the
physiochemical deterioration of ‘Coorg’ mandarins in storage.
The improved marketable condition of treated fruits after storage was due
to reduced weights loss and retention of Vitamin-C.
Ethylene Oxide:
Mangoes treated with ethylene oxide also show a definite delay in
ripening.
Ethylene Absorbents:
Waxing, low O2, High CO2, and ripening inhibitors are sometimes
combined to prolong storage life. Banana is packed in film bag containing
KmnO4 ( to absorb C2H4).

The ethylene control strategy includes prevention of exposure of plants to
biologically active levels of ethylene, reducing the tissue perception of
atmospheric ethylene, and preventing the tissue response to perceived
ethylene.
Ethylene damage can be reduced by (i) adequate ventilation, (ii) reduction
of O2 and increase in CO2 levels, (iii) reducing temperature, (iv) avoiding
storage and transportation of ethylene producers and sensitive produce,
and (v) reduction of ethylene by forcing air through filters of activated
charcoal, potassium permanganate (KMnO4) or purafil and oxidation by UV
light.
Potassium permanganate, the most accepted ethylene remover used
commercially, oxidizes ethylene into ethylene glycol and often is
incorporated into different carrier materials such as activated alumina and
silica gel.
It is applied in sachets, tubes and blankets in storage and transportation
of fresh fruits and vegetables. When used in conjunction with modified-

The fading distinctions between classical patterns of ripening in climacteric and
non-climacteric fruit and the ubiquity of ethylene—An overview
Vijay Paul, Rakesh Pandey, and Girish C. Srivastava
The process of fruit ripening is normally viewed distinctly in climacteric and non-
climacteric fruits. But, many fruits such as guava, melon, Japanese plum, Asian
pear and pepper show climacteric as well as non-climacteric behaviour
depending on the cultivar or genotype.
Guava
Ethylene was found to be necessary for skin colour changes and firmness loss
during ripening. These characteristics classify guava as a climacteric fruit. The
exogenous application of ethylene to these fruits at the mature-light green stage
had no effect on the ripening process. This evidence contradicts classification of
‘Pedro Sato’ guava as a traditional climacteric fruit.
Based on these findings, Azzolini et al. (2005) concluded that classification of
guava fruit as climacteric or non-climacteric varies with cultivars

Pepper
Capsicum fruits are classified as non-climacteric based on the patterns of
CO2 and ethylene production (Saltveit 1977; Lurie et al. 1986; Lu et al. 1990;
Biles et al. 1993).
However, some hot pepper cultivars are climacteric (Gross et al. 1986), indicating
that classification of capsicum as non-climacteric may be inconclusive.
Further, some cultivars seem to be ethylene insensitive, while in others
continuous treatment with exogenous ethylene has been shown to accelerate
ripening (Armitage 1989) and to up-regulate the expression of ripening specific
genes

Ripening of Climacteric and Non-Climacteric Fruits: An Overview

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