2. Introduction
• RIPENING-
• Ripening indicates sequence of changes in
texture ,colour ,flavour, which leads to a state
at which it became acceptable by the
consumers.
• Ripening is initiated only after the fruit has
attained maturity.
• It is the natural irreversible process of ageing &
has been called as fruit ageing.
3.
4. Enzymatic Changes
• The major enzymes implicated in softening of fruits are
pectineasteraes,polygalacturonase,β-(1-4)gluconase or
cellulase and β-galactosidase.
The mode of action of these enzymes are as follows
• Pectineasterase –Act to remove the methyl group from
the C-6 position of a galacturonic acid.
• Polygalacturonase-Hydrolyses the α(1-4) link between
adjacent dimethylated galacturonic acid residue.
• Cellulase-Hydrolyses the β-(1-4) link between adjacent
glucose residue
• β-galactosidase - In some cases attacks on native
galactan polymar.
5. • Cellulose enzymes:..
• This enzyme play a key role in textural
changes .
• These enzymes are involved in softening of
tissue and hydrolyses the β(1-4) link between
adjacent glucose residue.
• Cellulase has been described in many
ripening fruits ; perhaps the most active
source is the avocado but the enzyme has
also been found in litchi, banana,pineapple,
date and peach
6. • Amylase enzyme: Increase during ripening of
fruits such as in mango, banana, pear.etc. thus
leading to the accumulation of sugar.
• Starch metabolising enzymes and their mode of
action
• α-amylase -Hydrolyses the α (1-4) linkages of
amylose at random to produce a mixture of
glucose and maltose
• β-amylaes –Attack the penultimate linkage and
releases only maltose
• Starch phosphorylase-Hydrolyses the terminal α
(1-4) linkages to give glucose 1-phosphate,which
can be converted to glucose phosphate mutase
• α-1,6-glucosidase - attacks α 1-6 glucose
linkages of amylopectin
7. • Sucrose phosphate synthetase and invertase :
Sucrose phosphate synthetase breakdown the
starch into sucrose during ripening and then
sucrose is breakdown into glucose and fructose
by the action of invertase enzyme.
• Lipase: Lipase activity is increase during
ripening of avocado with parallel increase in
fatty acid.
• Malic enzyme: malic enzyme degrades malic
acid in apple , mango, grapes,etc.. increased
during ripening.
8. • Citrate synthetase,: This enzyme is mainly found in
citric fruits and it synthesizes citric acid, citrate
synthetase found in citrus.
• Acid phosphatase.: It involved in carotenoid
biosynthesis increase during ripening of mango and
banana.
• Phenylalanine ammonia lyase and flavone synthase
are key enzymes for the synthesis of anthocyanins.
• The important group of enzymes responsible for the
metabolism of phenolics is the polyphenol oxidase
(PPO) which are of two type catechol oxidase and
laccase which catalyse the oxidation of O-diphenols
and P-diphenols, respectively, and have been
classified together under the general nature of
monophenol mono oxygenase.
9. Changes in pectic enzymes and cellulase activity
during guava fruit ripening
Abu-Bakr A. Abu-Goukh*, Hind A. Bashir,2002
• Changes in activities of the cell wall degrading
enzymes, pectinesterase (PE), polygalacturonase
(PG) and cellulase, were studied during the
ripening of white- and pink-fleshed guava fruit
types. PE activity increased in both guava types
up to the climacteric peak of respiration (flesh
firmness of 1.21 kg/cm2) and subsequently
decreased. Activities of PG and cellulase
increased progressively during the ripening of
both guava fruit types with a high correlation
between the increase in the activity of the two
enzymes and the loss of fruit flesh firmness.
10.
11.
12. Comparison of cell wall degrading enzyme activities during ripening of
guava fruit on-tree and in-storage
Arti Sharma*, R.K. Sharma, Saleem Siddiqui and Bindiya Sharma
Department of Horticulture, CCS Haryana Agricultural University, Hisar 125 004, Haryana
13.
14.
15.
16.
17. Biochemistry of Fruit Ripening of Guava (Psidium guajava L.):
Compositional and Enzymatic Changes
NISHA JAIN, KAMAL DHAWAN,¤ SARLA MALHOTRA
& RANDHIR SINGH
18.
19. Change in texture
• The term such as firmness , crispness, mealiness ,
juiciness & hardiness are all related to the texture of
fruits and is controlled by the wall to wall adhesion of
cells.
• Changes in fruit firmness increase its susceptibility to
the attack from pathogens and in the latter stages of
ripening or after long storage periods, it confers
undesirable texture to the consumer’s perception.
• In fact, excessive softening of fruits is the main factor
responsible for limitations of shelf-life,
transportability and storage, for increased occurrence
of physical damages during handling and for higher
susceptibility to pests and diseases
• Fruit firmness and texture also affect the integrity of
processed fruits.
20. The metabolic events responsible for the textural
changes in fruits are believed to involve
• Loss in turgor pressure
• Degradation and other physiological changes in the
composition of membranes
• Modifications in the symplast/ apoplast relations
• Degradation of starch and
• Modifications in the cell wall structure and dynamics.
• Although the relative contribution of each event in
fruit ripening is not clear, and probably depends on
the species, changes in cell wall composition,
especially cell wall mechanical strength and cell-to-
cell adhesion, have been considered to be the most
important factors
21. • Fruit became soft on ripening , mainly due to the dis
solulation of pectic substances in the cell walls.
• The softening is due to enzymatic hydrolysis of
polysacccharides.
• The cell wall is made up of cellulose, hemicellulase ,
calcium pectate, poly uronides & glycoprotein.
• The enzyme pectinase break down pectin between
the fruit cells resulting in softening of the fruit
• In the cell wall,the changes particularly in the middle
lamella which is rich in pectic polysaccharides are
degrade and solubilised during ripening.
• During this softening there is a loss of neutral sugars
(galactose and arabinose) and acidic pectin
(rhamnogalacturonan)
22. Changes in papaya cell walls during fruit ripening
Robert E. Paull a,*, Ken Gross b, Yunxia Qiu a
• The apparent molecular mass range of different extractable fractions of
papaya fruit pectin and hemicellulose during fruit ripening was
determined. The pectin molecular mass declined and the solubility of
pectin in cyclohexan ediaminotetraacetic acid and Na₂CO₃ solutions
increased during ripening. The molecular mass decreased and the
solubility of hemicelluoase in KOH increased during ripening. Water
soluble uronic acid increased 6-fold during ripening as the yield of cell wall
material declined. The loss of high molecular mass pectins decreased
throughout ripening while the demethylation rate was greater early in
ripening. Changes in pectin molecular size did not parallel loss of fruit
firmness during early ripening. The pectin fractions were mainly
composed of rhamnose, glucose, xylose, galactose, mannose and
arabinose, in decreasing order of concentration. Non-cellulosic glucose
and xylose were the main neutral sugars in the hemicellulose fraction
followed by mannose and galactose and traces of rhamnose and
arabinose. These results suggested that pectin hydrolysis and the
modification of hemicellulose both were involved in papaya fruit
softening. Pectin hydrolysis was apparently more important during the
late phase of fruit softening..
23. Changes in activities of cell wall hydrolases during
ethylene-induced ripening in banana:
effect of 1-MCP, ABA and IAA
Seemi Lohani, Prabodh K. Trivedi, Pravendra Nath
• Softening during ripening in climacteric fruit is generally attributed to
degradation in cell wall assembly, particularly the solublization of pectin.
These changes could involve increased activities of various cell wall
hydrolases. Their activity is believed to be regulated by ripening-related
hormones and/or other signal molecules. Activities of pectin methyl
esterase (PME), polygalacturonase (PG), pectate lyase (PL) and cellulase
in banana cv. dwarf cavendish fruit were measured over a period of 7
days after ripening was initiated with ethylene. Effects of treatments
with 1-methylcyclopropene (1-MCP), abscisic acid (ABA) and indole
acetic acid (IAA) on activities of these hydrolases were measured in
order to help elucidate their roles during banana ripening. Ethylene
stimulated activities of all four enzymes, at best differentially. 1-MCP and
IAA suppressed the ethylene effects. ABA stimulated activities of all
hydrolases except polygalacturonase. ABA stimulation was most evident
for pectate lyase. Thus ethylene plays a major role in up-regulating the
activities of various cell wall hydrolases. In contrast IAA suppresses their
activity. ABA can enhance softening with or without ethylene.
24. Changes in respiration
• Respiration is a most deteriorating process of
the harvested fruits which leads to the oxidative
breakdown of the complex materials
(carbohydrates or acids) of cell into simpler
molecules (CO₂ and water) with the concurrent
production of energy required by the cell for the
completion of chemical reactions.
• C₆H₁₂O₆+6O₂→6CO₂+6H ₂O+ENERGY
• In addition to glucose, some other substances
like organic acids or fat can also be used as the
respiratory substrate in the fruit.
25. • The respiratory quotient or RQ (CO₂
produced in ml/O ₂ consumed in ml) which
may be 1 for glucose,<1 for fat,>1 for organic
acids
• Fruits can be climacteric or non climacteric
depending upon the presence or absence of
occurrence of peak in CO₂ production during
ripening
• During ripening the rate of respiration
increases –this sudden upsurge in respiration
is known as climacteric rise which is followed
by deterioration & senescence
26. • Examples of climacteric fruits are banana,
guava, mango, fig, chiku , jackfruit , papaya
etc
• In fruits like lemon, lime, pomegranate, grape
& pineapple are non climacteric in nature
where there is a steady rate of respiration
27.
28. Temperature & Respiration
• Temperature is the most important factor influencing the
postharvest life of the given commodity.
• Temperature dictates the speed of chemical reactions
including respiration.
• Typically, for every increase of 10oC, the respiration increases
between 2 and 4 fold.
R1=Respiration at Temperature 1 (T1)
R2=Respiration at Temperature 2 (T2)
Q10= R2
R1
10
T2-T1
29. Respiration rate of different fruit at
20-25⁰C
Fruit Respiration peak
Apple 16mg/kg/hr
Avocado 155mg/kg/hr
Banana 140-200mg/kg/hr
Fig 50-100mg/kg/hr
Mango 82mg/kg/hr
Peach 35mg/kg/hr
Pear 49mg/kg/hr
Ber 140mg/kg/hr
30.
31. EFFECTS OF WATER LOSS ON RESPIRATION,
ETHYLENE PRODUCTION AND RIPENING OF BANANA
FRUIT
• Fernando Luiz Finger2, Rolf Puschmann3 and Raimundo Santos Barros3
• Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, 36571-
000, Brasil
• ABSTRACT- This study reports the effects of water loss on
postharvest life of banana (Musa acuminata Colla) fruits. Fresh
mass losses of 5% and higher promoted a shortening in
preclimacteric life of fruits and induced a decrease of maximal
rates of respiration and ethylene production during climacteric
ripening. Preclimacteric ethylene production was stimulated by
water stress; however, it did not induce chlorophyll degradation.
Fruit exhibiting fresh mass loss of 20% showed an abnormal
ripening with a decreased pulp softening and excessive brown
color of skin.
32. Effect of water stress on the maximal rates of respiration
and ethylene production during banana fruit ripening.
33. Changes in Transpiration
• Transpiration is the loss of moisture from the fruit
surface resulting in shriveling of the produce.
• Fresh produce continues to lose water after
harvest,but unlike the growing plant it can no
longer replace lost water from the soil and so
must use up its water content remaining at
harvest. This loss of water from fresh produce
after harvest is a serious problem ,causing
shrinkage and loss of weight
34. Water Loss resulting a direct loss of salable
weight as well as quality loss:
• Appearance quality - wilting, shriveling,
and accelerated development of injuries.
• Textural quality – loss of crispness,
juiciness, etc.
• Nutritional quality – e.g. vitamins A & C.
Rate of water loss influenced by:
• Environmental factors – e.g. relative
humidity.
• Anatomical factors – stomates, hairs, etc.
35. Papaya endoxylanase biochemical characterization and isoforms expressed
during fruit ripening
J. Jesús Iniestra-Gonzáleza et al ,2o11
36.
37. Role of putrescine in regulating fruit softening and antioxidativeenzyme
systems in ‘Samar Bahisht Chaunsa’ mangoKashif Razzaqa, Ahmad Sattar
Khana,∗, Aman Ullah Malika,Muhammad Shahidb, Sami Ullahaa
38. References
• Postharvest Biology and Technology 96 (2014)
23–32, Role of putrescine in regulating fruit
softening and antioxidativeenzyme systems in
‘Samar Bahisht Chaunsa’ mango
• Postharvest Biology and Technology 81 (2013)
13–22, Papaya endoxylanase biochemical
characterization and isoforms expressed
during fruit ripening
• Comparison of cell wall degrading enzyme
activities during ripening of guava fruit on-tree
and in-storage, Indian J. Hort. 69(3), September
2012: 409-415
39. • Biochemistry of Fruit Ripening of Guava
(Psidium guajava L.):Compositional and
Enzymatic Changes, Plant Foods for Human
Nutrition 58: 309–315, 2003. Kluwer Academic
Publishers. Printed in the Netherlands.
• DOI: 10.1093/jxb/erh227 Advance Access
publication 30 July, 2004
• Post harvest biology and technology for
preserving fruit quality by Daniel Valero & Maria
Serrano
• Post harvest technology of fruits and vegetables
by L.R.Verma & V.K.Joshi
