This document summarizes the chemical properties of several natural food colors, including chlorophyll, carotenoids, anthocyanins, flavonoids, and tannins. It describes their sources, uses as food colorants, and key chemical characteristics such as solubility, reactivity, interactions with proteins, and effects of pH and temperature. Chlorophyll is oil-soluble and green, carotenoids are lipophilic and heat stable, anthocyanins exist in different structures depending on pH, and flavonoids and tannins can be crystalline, colored, and affect taste.

1. Chemical properties of natural colors, chlorophyll,
carotenoids, anthocyanins, flavonoids, tannins
Submitted by
Towkir Ahmed Ove
M.S in Food Science & Nutrition

2. • Food Colorant
Colorants are defined as substances that modify the perceived color of objects, or impart
color to otherwise colorless objects.
Food color is any substance that is added to food or drink to change its color. Food
coloring is used both in commercial food production and in domestic cooking.
• Purpose of food coloring
Offsetting color loss due to light, air, extremes of temperature, moisture, and storage
conditions.
Masking natural variations in color.
Enhancing naturally occurring colors.
Providing identity to foods.
Protecting flavors and vitamins from damage by light.
Decorative or artistic purposes such as cake icing.

3. • There are major three categories of food colors
1. Natural colors
2. Synthetic colors
3. Lakes and dyes

4. • Natural Food Color
Natural Food Color is any dye, pigment or any other substance obtained from
vegetable, animal, mineral, or source capable of coloring food drug, cosmetic
or any part of human body, colors come from variety of sources such as seeds,
fruits, vegetables, algae & insect.
Natural food colorings are
• Chlorophyll (E 140)
• Anthocyanin (E 163)
• Carotenoids (E 160)
• Flavonoids
• Tannins
• Betanin (E162)
• Paprika (E160c)

5. • Chlorophyll is the most widely distributed natural plant pigment, present in all
green leafy vegetables. It is a green, oil soluble color.
• Two types of chlorophyll exist in the photosystems of green plants: chlorophyll a
and b.
• Uses : It is mostly used in medicines, processed foods, ice creams, sugar
confectionery, dairy products jams and jellies.
Chlorophyll (E140)

6. Chemical properties of Chlorophyll
Chlorophyll does not participate in the alteration of hydrogen or hydrogen
oxidation-reduction, while alone electron alteration (i.e., assets and losses arising
from electron redox) and conjugated alteration (direct activity transfer) way to
participate in the activity transfer.
Both Chlorophyll a & b are insoluble in water but soluble in ethanol, ether, pyridine
The melting point of Chlorophyll a is 152 °C and for Chlorophyll b is 125°C.
Chlorophyll absorbs light most strongly in the blue and red but poorly in the green
portions of the electromagnetic spectrum, hence the green color of chlorophyll-
containing tissues such as plant leaves.
Chlorophyll
(E140)

7. • Carotenoids are a class of more than 600 naturally occurring pigments
synthesized by plants, algae, and photosynthetic bacteria.
• Most are oil soluble, heat stable and are not affected by pH change.
• uses of catotenoids include margarine, dairy products and soft drinks.
sources
 carrots
 plums
 apricots
 mangoes
 cantaloupes
Carotenoids (E 160)

8. Chemical properties of Carotenoids
1. Solubility
Carotenoids are highly lipophilic. They are insoluble in water and soluble in varying
degrees in organic solvents such as acetone, alcohol, ethyl ether, chloroform, and
ethyl acetate.
2. Chemical reactivity
Carotenoids can undergo many reactions with a wide variety of chemical reagents,
some of which might be similar to chemicals found in biological systems.
 The process that draws much attention in biological systems is the oxidation of
carotenoids, during which time they may function as biological antioxidants.
3. Protein binding
The best example of protein binding with β-carotene is the 15, 15’-dioxygenase of
intestinal and other tissues.
This enzyme requires, carotenoids with at least one unsubstituted O-ring which
allows cleavage to form a family of C20 compounds known as retinoids.

9. • Anthocyanins are a group of naturally occurring pigments that are responsible
for the red-blue color of many grains, fruits and vegetables.
• Used in drinks, jams and sugar confectionery.
Sources
blackberries.
blueberries.
cherries.
cranberries.
eggplant.
Anthocyanins (E 163)
grape juice.
plums.
prunes.

10. Chemical properties of Anthocyanins
It has been demonstrated that in acidic media, four anthocyanthin
structures, including the flavylium cation, the quinonoidol base, the carbinol
pseudo base and chalcone, exist in quilibrium.
The number of hydroxyl groups and type of sugar moieties, as well as the
acylated groups, obviously can influence the polarity, size, and spatial
conformations of individual compounds.
Many factors, such as pH, temperature, and light, presence of other phenolic
compounds, enzymes, metal ions, sugars, ascorbic acid, and oxygen have impact
on the stability of anthocyanins.
Anthocyanins generally are degraded at higher pH, however, some anthocyanins,
such as petanin are resistant to degradation at pH 8 and may be used effectively
as a food colorant.

11. • Flavonoids are a diverse group of phytonutrients (plant chemicals) found in
almost all fruits and vegetables. Along with carotenoids, they are responsible for
the vivid colors in fruits and vegetables.
Sources
Onions, tea, strawberries, kale, grapes, Brussels sprouts, citrus fruit, parsley, and
many spices are just a few natural foods rich in flavonoids.
Flavonoids

12. Chemical properties of Flavonoids
Flavonoids are crystalline compounds.
They are colored: yellow: flavones, flavonoles, chalcones, aurones; red:
anthocyanidins in acidic media; blue: anthocyanidins in alkaline media; colorless:
catechins, flavans, flavanones, leucoanthocyanidins, isoflavones
Flavonoid glycosides are generally soluble in water and alcohol but insoluble in
organic solvents; the aglycones (genins) are only sparingly soluble in water but
soluble in ether, chloroform.
Under the UV light flavonoids show fluorescence of different colors (yellow,
orange, brown, red).
Certain flavonoids also markedly affect the taste of foods: for example, some are
very bitter and astringent such as the flavanone glycoside naringin, which occurs
in the peel of grapefruit.

13. • Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that
bind to and precipitate proteins and various other organic compounds including
amino acids and alkaloids.
• Tannin is responsible for the astringency, colour, and some of the flavour in tea.
Sources
Grapes and pomegranates contain some tannins even as they ripen. Berries,
sorghum, barley, nuts, chocolate, rhubarb, squash and legumes, such as chickpeas
and beans, also contain tannins.
Tannins

14. Chemical properties Tannins
1. Precipitation
Tannins have ability to precipitate solutions of; Gelatin, Alkaloids, Glycosides,
Heavy metals, Proteins.
2. Anti-oxidizing properties
Because of accumulation of OH group on small size nucleus, these agents have
anti-oxidant nature.
3. Astringent
Tannins have property to react with protein of mucous membrane and cause
precipitation.
4. Carcinogenicity
Prolong use of tannin containing plant material is hazardous because it causes
cancer. Habitual use of Areca catechu can cause oral and esophageal cancer.

15. continued
5. Reaction with salts
6. Reaction with potassium ferricyanide and ammonia

16. Thank you All