Overview of the pigment Chlorophyll, its sources, types, structure, photoreceptors, benefits, stability, degradation, preservation during food processing and technologies associated with it.

1. CHLOROPHYLL
Chandrima Shrivastava

2. TOPICS
 SOURCES
 TYPES
 STRUCTURE
 CHLOROPHYLL IN PLANTS
 PHOTORECEPTORS
 USES AND BENEFITS
 CHLOROPHYLL DERIVATIVES
 STABILITY
 DEGRADATION
 PRESERVATION
 TECHNOLOGY

3. • dark, leafy greens
• fresh herbs
• blue-green algae
• sprouts
• wheatgrass
• green tea
• green vegetables
and fruits
• sea vegetables
SOURCES

4. TYPES AND SOURCES
Global satellite map of chlorophyll in surface waters: higher
chlorophyll shown in green, yellow, and red; lower in aqua,
blue, or purple.
Chlorophyll indicates the growth of phytoplankton. (Image
courtesy NASA)
Chlorophyll a: occurs universally, mostly in plants
Chlorophyll b: mostly in plants
Chlorophyll c1, c2, c3: found together with chlorophyll a in
marine algae
Chlorophyll d: cyanobacteria,
red algae
Chlorophyll f: cyanobacteria
• In most green plants, chlorophyll
a and b are in the ratio 3:1
• Chlorophyll f absorbs in the
infrared region

5. STRUCTURE
• Chlorophyll is a chlorin pigment, structurally
similar to porphyrin pigments such as heme.
It contains a fully conjugated tetrapyrrole
system (18 pi-electrons)
• The chlorin ring can have several different
side chains, usually a long phytol chain.

6. STRUCTURES
Chlorophyll a
Chlorophyll c1
Chlorophyll dChlorophyll b Chlorophyll c2
(IMAGE SOURCE: http://en.wikipedia.org/wiki/Chlorophy

7. CHLOROPHYLL IN PLANTS
• For efficient photosynthesis,
chlorophyll needs to be attached to
the backbone of a complex protein.
• Attached to the porphyrin is a C20 hydrophobic
chain (phytol) which makes chlorophyll fat-soluble
and insoluble in water and it interacts with the
proteins of the thylakoids.

8. PHOTORECEPTORS
• Effective photoreceptors: conjugated tetrapyrrole
system
• Chlorophylls a and b complement each other in
absorbing sunlight.
• In the green region of the spectrum (500-600nm), light
is mostly reflected, hence plants appear green.
• Chlorophyll absorbs strongly, thus masking other less
intense colors from molecules like carotene, quercetin.

9. USES AND BENEFITS
• Chlorophyll absorbs
energy from the sun and
facilitates
photosynthesis in
plants.
• Chlorophyll is registered
as a food additive
(colorant), and its E
number is E140.
• Chlorophyll is known to
detoxify toxins that
cause cancer.
• Chlorophyll acts like a
physiological stimulant
of red blood cells in the
bone marrow.

10. CHLOROPHYLL
DERIVATIVES
CHLOROPHYLL PYROPHEOPHYTINPHEOPHYTIN
CHLOROPHYLLIDE PHEOPHORBIDE PYROPHEOPHORBIDE
(REF: Jackson, A.H., Structure, properties and distribution of chlorophylls, in Chemistry and Biochemistry of Plant Pigments, Vol. 2,
2nd ed., Goodwin, T.W., Ed., Academic Press, New York, 1976, 1)
-Mg
-Mg
-CO2CH3
-CO2CH3
-PHYTOL
-PHYTOL-PHYTOLChlorophyllase
• Central Mg atom is removed under acidic conditions, replacing it with H+, forming
pheophytins.
• Hydrolysis of the phytyl group of pheophytin with acid or alkali forms pheophorbides.
• Cleavage of the phytyl group without removal of Mg atom produces chlorophyllides.
• Prolonged heating causes decarbomethoxylation at C-10 giving rise to pyro-
derivatives.

11. STABILITY
 In heated vegetables chlorophyll is degraded by change in pH:
Acidic pH(3) - chlorophyll is unstable
Basic pH(9) - chlorophyll is stable
 When plant material is heated, i.e. cooked, the plant cell membranes
break down and cause acid to be released, thus decreasing the pH of the
surrounding solution.
 Mg2+ atom is easily displaced by 2 hydrogen ions result in formation of
olive-brown pheophytin. The reaction is irreversible in aqueous medium.
 Prolonged heating further degrade pheophytin into Pyropheophytin
which has an olive drab color
 The heat induced cellular degradation can also predispose the chlorophyll
pigments to photo-degradation in which they chemically decompose in
the presence of light.

12. EXAMPLES OF
DEGRADATION
Fruit maturation
It may occur on or off the plant.
 Ripening of tomatoes (chlorophyll  colorless compounds); induced by ethylene
 De-greening of bananas (chlorophyll  colorless compounds); induced by
ethylene
 De-greening of lemons and oranges (chlorophyll  colorless compounds);
induced by ethylene
http://plantphys.info/plants_human/fruitgrowripe.sh

13.  Canning of peas [chlorophyll  pheophytin (olive brown)]; induced by heat
 Brining of olives [chlorophyll  pheophytin (olive brown)  pheophorbide
(olive brown) and chlorophyll  chlorophyllide (blue green) 
pheophorbide]; induced by acid and chlorophyllase
 Blanching of snap beans, turnip greens and okra[chlorophyll  pheophytin
(olive brown)]; induced by heat
 Coleslaw processing [chlorophyll  pheophytin (olive brown) 
pheophorbide (olive brown)]; induced by acid and chlorophyllase
PROCESSIN
G
(REF: Heaton, J.W. and Marangoni, A.G., Chlorophyll degradation in processed foods and senescent plant tissues, Trends Food Sci.

14. (IMG SOURCE:
SENESCENCE
Senescence refers to the endogenously-controlled deteriorative changes,
which are natural causes of death in cells, tissues, organs or organisms.
• Ready-to-eat salads (chlorophyll  colorless compounds); induced by
ethylene
• Stored cabbage heads (chlorophyll  colorless compounds); induced by
ethylene

15. PROPOSED MECHANISM FOR DEGRADATION
(IMG SOURCE: http://www2.hu-

16. CHLOROPHYLL DEGRADATION
MECHANISM
 The process involves interconversion of chlorophyll a and b
(chlorophyll cycle), and the release of chlorophyll from its protein
complex followed by dephytlization and pheophytinization.
 Oxidation of the ring structure to chlorins occurs and ultimately
colorless end products form.
 Chlorophylls are degraded in the chloroplast by enzyme-catalyzed
process via pheophorbide a and the red chlorophyll catabolite (RCC)
to give primary fluorescent chlorophyll catabolites (pFCC, or its Cl-
epimer, epipFCC).
 pFCCs are modified further by unidentified hydroxylating enzymes.
 When carrying a free propionic acid group, FCCs are transported into
the vacuole where they isomerize by a spontaneous acid catalyzed
reaction to the corresponding nonfluorescent chlorophyll catabolites
(NCCs).

17. PRESERVATION
 Freezing: Low temperature storage preserves chlorophylls; however,
cold stored products may develop chilling injury symptoms.
 Blanching: Thermal treatment to inactivate enzymes that catalyze
down-grading reactions during storage.
 Irradiation: Treatment with gamma radiation in combination with
storage at 8o or 10oC , does not alter sensory attributes like color.
(IMAGE SOURCE: http://mamaldiane.com/freezing-fresh-basil-whole-leaf/)
FREEZING BLANCHING

18.  Reducing moisture content of vegetables or lowering the water
activity: Addition of agents like KMnO4, which absorbs ethylene, and
sorbitol, which reduces water activity.
 By reducing cooking time and boiling vegetables with the pan lid off
to allow the escape of volatile acids, the production of pheophytin
and discoloration can be minimised.
 Alkaline Medium: Adding a small amount of sodium bicarbonate
(NaHCO3) to the water during boiling raises the pH.
 Substitution of Mg2+: Zn2+ or Cu2+ salts help retain bright green color
of vegetables. Sodium copper chlorophyllin gives blue-green color to
canned foods. Though copper is toxic, the concentration level is too
low to be a toxic hazard.
PRESERVATION

19. PRESERVATI
ON
 Artificial colorants: Tartrazine and green S (dyes) added to restore color.
 Addition of maillard reaction products (MRPs): During heat treatment,
chlorophyll degradation to pheophytin can be minimized by the addition
of MRPs to improve colour stability.
 Gibberellic acid (GA): Chlorophyll degradation delayed in GA-treated
crops
(Ref: Kumar R., Rajamanickam R., Nadanasabapathi S., Effect of Maillard Reaction Products (MRP) on Chlorophyll Stability in Green
Gibberellic acid (GA) Green S

20. TECHNOLOGY
 Production of chlorophyll using algae:
Cyanobacterium Spirulina
 Chlorophyll-Based Phototransistor: Coat a
layer of graphene with chlorophyll
 Artificial leaf: Water-gel-based artificial leaves
containing chlorophyll produce electricity Cyanobacterium
Spirulina
(REF: http://www.technologyreview.com/view/516161/materials-scientists-build-chlorophyll-based-phototransistor/)

21.  Chlorophyll as a water quality parameter
 Infrared chlorophyll to boost solar cells
 Chlorophyll for cancer prevention
TECHNOLOGY
http://www.newscientist.com/article/dn19338-infrared-chlorophyll-could-boost-solar-

22. Thank You