Anthocyanin
Anthocyanins are water-soluble pigments seen in many cell vacuoles. Their colour changes according to pH. They might be purple, blue, red or black pigments. For example, food plants such as black soybean, blueberry, purple cauliflower, raspberry contain anthocyanin pigment. This pigment not only occurs in fruits and flowers but also in stems, leaves and roots.
They are odourless pigments and can be mildly astringent.
Effect of anthocyanin in Humans
Initially, the food source with anthocyanin pigments were considered to be antioxidant-rich. Later studies revealed that anthocyanin has no direct effect on the antioxidant properties in a food source. Also, their effect on human biological functions and diseases lack conclusive evidence. Moreover, anthocyanin pigment is approved as a food colourant in many countries.
Anthocyanidin
Anthocyanidins are sugar-free plant pigments. Sugar molecules can be added to the anthocyanidins to derive the anthocyanin pigment. They also change colour based on pH. They can be blue, bluish-green, purple or red. At acidic conditions, coloured anthocyanidins are observed. At basic conditions, it forms colourless compounds.
Approximately 20% of anthocyanin pigments are based on methylated anthocyanidins like malvidin, peonidin and petunidin.
Difference between Anthocyanin and Anthocyanidin
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Anthocyanin |
Anthocyanidin |
|---|---|
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They are plant pigments that are derived from anthocyanidin by coupling sugar molecules. |
They are sugar-free counterparts of anthocyanin pigments. |
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At acidic conditions (pH<7), it appears in red. |
At acidic conditions (pH<7)), it shows colour. |
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At neutral conditions, it appears purple and at alkaline conditions (pH>7) it appears greenish-yellow. |
At basic conditions (pH>7), it appears colourless. |
Frequently Asked Questions
What are biological pigments?
These are coloured substances produced by living organisms as a result of selective absorption. This includes plants, algae, bacteria and animal pigments. For example, melanin is a biological pigment seen in skin, fur, feathers, etc. Likewise, chlorophyll is a biological pigment in plants and algae.
What are the functions of flavonoids in plants?
Flavonoids or bioflavonoids are secondary metabolites seen in plants. They are major plant pigments. In flowers, they produce bright pigment that helps to attract pollinators. They are also involved in nitrogen fixation and UV filtration. Anthocyanidins and anthoxanthins are some naturally occurring flavonoid compounds.
What are anthoxanthins?
Anthoxanthins are also a type of water-soluble flavonoid pigments. They can be white, cream, creamy-yellow or colourless pigments. Example – White Cauliflower.
Also Read: Biological Pigments in Plants
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