2. INTRODUCTION
• Carotenoids, also called Tetraterpenoids responsible for bright red, yellow and orange
hues in many fruits and vegetables.
• These are long chain, conjugated hydrocarbons containing isoprene subunit.
• It imparts photosynthesis , photoprotection , plant colouration and cell signalling.
• This class of phytonutrients are found in variety of organisms varying from bacteria algae
to plants.
• Carotenoids also act as antioxidants in the human body. They have strong cancer-fighting
properties.
3. • There are over 1,100 known carotenoids which can be further categorized into two
classes, xanthophylls (which contain oxygen) and carotenes (which are purely
hydrocarbons and contain no oxygen)
• Animals cannot manufacture carotenoids by themselves so need to be consumed from
outside along with a fat moiety that makes it easy to process.
• Till date scientists discovered >600 different types of carotenoids.
• The most common ones in the Western diet, and the most studied, are alpha-carotene,
beta-carotene, beta cryptoxanthin , lutein, zeaxanthin and lycopene.
• In birds it plays a vital role that differentiates gender and are indicative of sexual maturity
and attraction.
• In general, carotenoids absorb wavelengths ranging from 400 to 550 nanometers (violet
to green light)
4. STRUCTURE
• Carotenoids are oil-soluble molecules.
• Most are comprised of 40 branched carbon units bonded together.
• Structurally, they're composed of conjugated double bonds, meaning the carbon
units are bonded together by alternating single and double bonds.
• The amount of conjugated double bonds a carotenoid contains changes the
wavelength of light that it can absorb. As a result, carotenoids vary in color from
red, orange, and yellow.
5. CLASSIFICATION
• They are divided into 2 broad categories :
1. Carotenes
2. Xanthophylls
• The unoxygenated (oxygen free) carotenoids such as α-carotene, β-carotene,
and lycopene, are known as carotenes.
• Carotenoids with molecules containing oxygen, such as lutein and zeaxanthin, are
known as xanthophylls.
6.
7. FUNCTIONS
• Foods high in carotenoids appear to be protective against head and neck cancers.
• Carotenoids also participate in different types of cell signaling.
• They are able to signal the production of absicisic acid, which regulates :
a. Seed dormancy
b. Embryo maturation and germination,
c. Cell division and elongation
d. Floral growth, and stress responses, etc.
• In food industries, the carotenoids are mainly used as restoring colorants, used in
products submitted to intense processing/storage
8. • Carotenoids are converted to vitamin A as the body needs, with varying degrees of
conversion efficiency.
• Vitamin A is important for
a. Growth
b. Development
c. Maintenance of epithelial tissues
d. Reproduction
e. Immune system
• Carotenoids quench singlet oxygen, remove peroxy radicals, modulate carcinogen
metabolism.
• Inhibit cell proliferation
• Stimulate communication between cells (gap junctions), and increase the immune
response
