This document presents an overview of fruit ripening physiology and biochemistry. It discusses how ripening involves changes in composition, including conversion of starch to sugar and changes in color, firmness, and aroma. The key metabolic changes that occur are increases in biosynthesis and respiration, mediated by the ripening hormone ethylene. Ripening involves degradation of chlorophyll and synthesis of pigments, hydrolysis of starch and production of aromas, and enzymatic breakdown of cell walls and pectin that causes softening. The document also examines ethylene biosynthesis and the roles of various enzymes in the ripening process.

1. Physiology and Biochemistry
of
Fruit Ripening
Presented By
1) Vivek yadav
Department of Horticulture
School of life Sciences
Sikkim University

2. INTRODUCTION
• Ripening is the process by which fruits attain their desirable flavor, quality,
color, palatable nature and other textural properties.
• Ripening is associated with change in composition i.e.
• conversion of starch to sugar.
• Change in colour
• Change in firmness
• Shape and size
• Odour /smell
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3. Changes occurs During Ripening
• Dev. Of wax on screen
• Flavour volatiles
• Proteins
• Organic acid
• Carbohydrate composition
• Pectic substance
• Tissue rigidity
• Ethylene
• Denaturation of chlorophyll
Ripening
Seed
maturation
Deg.
chlorophyll
Abscission
Pectic sub.
Rigidity
Organic
acid
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4. Metabolic Changes
• Increases in biosynthesis
• Evolution of ripening hormone
• Increase in respiration mediated
• Alternation of cell structure
• Hydration of cell wall
• Decrease in structural integrity
• Increase in intercellular space
In fruit ripening
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5. Respiratory Pattern
• Climacteric
• Non climacteric
Climacteric Non climacteric
Respiration Increase
Not shows respiratory
climacteric
Ethylene More production Less amount
Detachment ripening occurs On tree only
Fruits
Apple,Apricot,Banana,
Guava,Kiwifruit
Cherry,Cucumber,Grape,
Grapefruit,Lemon
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6. Ripening Graph
Growth, respiration and ethylene production
in climacteric and non climacteric fruits
Ethylene
production

7. Mechanism of Ripening
Pathway of ethylene Biosynthesis and Metabolism
• Malonyl ACC
• ACC synthase
SAM
• ACC oxidase
• Keto butyrate
ACC
• Oxidation
products
C2H2
• Texture
• Colour
• taste
Fruit
ripening
SAM =S- Adenosylmethionine
ACC =Aminocyclopropane carboxylic acid
Yang and Hoffman 1993
At the onset of fruit
ripening , expression of
multiple ACC synthase
genes are activated ,
resulting in increase
production
Deamination of ACC to α- kitobutrate
by over expressing ACC deaminize
enzyme also inhibited ethylene
formation and fruit ripening.

8. Degradation of Chlorophyll and Pigment Synthesis
Chlorophyll (green)
Pheoporbide
(Brown )
Chlorins, Purpurins (colourless product)
Chlorophyllin (bright green )
Phaeophytin (Olive green )
Phytol
Mg++
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 Degradation of chlorophyll
due to Chlorophyllase enzyme.
 Splitting of chlorophyll into
Phytol chain and porphyrin.
 Loss of Mg ++ ion and
conversion of porphyrin into
Phaeophytin.
 Change in tetrapyrolic chain
and it becomes bilviridin.
 Oxidation or saturation of
double bonds.
Chlorophyllase
Mg +

9. Hydrolysis and Aroma
Enzyme Mode of action
α Amylase Mixture of glucose and maltose
Starch phosphorylase Glucose 6-phosophate
α (1-6) glucosidase Amylopectin
Starch to sugars …………
Aroma volatile after ripening …..
Product Compound
Apple Ethyle 2- methyle butyrate
Banana 2 hexanol
Lemon Citral
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10. Textural changes
Textural
changes Enzyme degradation of polysaccharides
Different rates i.e. Degree
Breakdown of starch
Pectic substance
Hydrolysis starch- firmness
Cell wall
breakdown PG (Polygalacturonase)
PME (Pectin methylesterase )
Other hydrolases
Cell wall
Degradation
Depolymerisation Deesertification
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11. Phenolic Compound
S NO Crop Phenol Status
01. Grapes Flavon-3-ol monomers Decreases
02. Loquat Hydrobenzoic acid Decreases
03. Citrus Limonoids Decreases
Astringency to fruit e.g. Tannins.
Involve in oxidative browning
due to Polyphenoloxidase
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12. Enzyme Activity
Softening –Pectin esterase
Oxidation- Catalse and
peroxidase
Glycolytic action- Glucose
phosphate isomerase
Hydrolytic action –Amylase
cellulose, beta amylase
Pigmentation- Chlorophyllase
Many of the chemical and physical affects
during ripening and after ripening processes
are attributed to the enzyme action.
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13. Fruit Firmness
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14. Enzymatic action11/8/2015 viveksu1194@hotmail.com 14
Unripe
Fruit
Green- Chlorophyll
Hard - Pectin
Sour – Acid
Mealy- Starch
Odourless- Large
orgs
Ripe fruit
Anthocyanin-
Red
Less pectin-
Soft
Neutral
Sugar sweet
+juicy
Small
orgs+odor
Hydrolase
Pectinase
Kinase
Amylase
Hydrolysis
Physical condition – Chemical cause Chemical cause-Physical condition

15. Regulation of Ripening
Ethylene
regulation
Regulation of
O2 andCO2
• MAS
• CAS
Chemical
treatment
• Calcium
• 1MCP
methylcyclopropane
Bioregulatores
• Auxin GA,CK
• Ehhylene ,ABA
Ionized
radiation
• Gamma
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16. 11/8/2015 viveksu1194@hotmail.com 16Thanking You