Natural food pigments

Question 1

State the food sources of anthocyanins

Answer 1

Fruits, vegetables and microorganisms.

Question 2

State the food sources of flavonoids

Answer 2

Fruits, vegetables and microorganisms.

Question 3

State the food sources of melanins

Answer 3

Shellfish, dried fruits, vegetables and microorganisms.

Question 4

Give 6 natural food pigments

Answer 4

1- anthocyanins
2- flavonoids
3- melanins
4- chlorophyll
5- heme
6- carotenoids

Question 5

Give three differences between chlorophyll a and b

Answer 5

a is :

• darker
• as a methyl group on C3 instead of a formyl
• absorbs at different wavelenghts

Question 6

complete : under acidic and heat conditions, chlorophyll will lose the ____ and become ___ which is ___ (color)

Answer 6

Mg2+
Pheophytin
dull green

Question 7

What color is pheophytin?

Answer 7

dull green

Question 8

What color is pheophorbide?

Answer 8

brown

Question 9

What color is chlorophyllide?

Answer 9

light green

Question 10

complete : under acidic and heat conditions, chlorophyllide will lose the ____ and become ___ which is ___ (color)

Answer 10

Mg2+
pheophorbide
brown

Question 11

complete : under the action of chlorophylase, chlorophyll will lose the ____ and become ___ which is ___ (color)

Answer 11

phytol
chlorophyllide
light green

Question 12

complete : under the action of chlorophylase, pheophytin will lose the ____ and become ___ which is ___ (color)

Answer 12

phytol
pheophorbide
brown

Question 13

complete : Fe also covalently linked to ____ in a ____ residue in globin (protein);

Answer 13

nitrogen

histidine

Question 14

What are the differences between chlorophyll and heme?

Answer 14

1. globin vs phytol side chain
2. liposoluble vs hydrosoluble
3. color red vs green
4. Fe central atom vs mg
5. side chain is linked to the fe in heme while it is on one of the pyroll in chlorophyll

Question 15

What are the similarities between chlorophyll and heme?

Answer 15

1. tetrapyroll ring
2. metal ion as central atom
3. massive side chain

Question 16

why does cooking change the color of heme?

Answer 16

because the iron is oxidized (Fe2+ to Fe3+) and the proteins are denatured

Question 17

When heme is red, the Fe is the ___ state and it is linked to ___.

Answer 17

reduced (Fe2+) and linked to oxygen.

Question 18

The oxymyoglbin is ___ (color)

Answer 18

red

Question 19

What is the name of the pigment formed when nitrite oxide is linked to the iron of the heme

Answer 19

nitrosomyoglobin

Question 20

What is the state of the iron in nitrosomyoglobin?

Answer 20

reduced (Fe2+)

Question 21

Ferric is when the Fe is in the state __ +

Answer 21

3+

Question 22

Ferrous is when the Fe is in the state ___ +

Answer 22

2+

Question 23

when Mb is in the presence of oxygen for a short time it will become ____ and the iron state will be ___

Answer 23

Mb-O2 (oxymyoglobin)

Fe2+

Question 24

When Mb is in presence of H2O without oxygen is will be ___ (color) and the iron state will be ___

Answer 24

purple / blue

reduced (Fe2+)

Question 25

when Mb is in the presence of oxygen for a long time it will become ____ and the iron state will be ___

Answer 25

metmyoglobin (Met-Mb)

ferric or oxidized (Fe3+)

Question 26

What is the name of the brown pigment created when you cook cured meats

Answer 26

nitrosohemichrome

Question 27

in nitrosomyoglobin the iron is in the state ___

Answer 27

Fe2+

Question 28

nitrosohemichrome, the iron is in the state ___

Answer 28

Fe3+

Question 29

Using redeucing agents containing ___ can lead to the formation of __

Answer 29

Sulfur (cystein)

sulfmyoglobin