Colourings lycopene

Lycopene, a carotenoid occurring mainly in tomatoes, is extensively applied as a natural colouring agent in food and food products. 

Lycopene contains only carbon and hydrogen while most pigments contain many other elements but nearly all contain double bonds. This chapter is about the properties, such as colour, of molecules that have several double bonds and that depend on the joining up or conjugation of the electrons in these double bonds. 

The colour quenching effect of carotenoids in liquid scintillation spectrometry has been studied in detail. The most efficient quenchers were lycopene [i/>, -carotene (225)] and echinenone [j8,/3-caroten-4-one (226)]. Use of the external standards ratio method to correct for colour quenching in the radioassay of carotenoids is justified.84... 

A variety of C4q carotenes do not yield vitamin A on oxidation and these variously have altered cyclic groups or no cyclic, groups at all and can be variously oxidized or reduced. Good examples are the widespread lutein (X —(IP)2—(PI)2—X ) (yellow) and the non-cyclic carotenes lycopene ( /, /-carotene the orange-red colour of tomatoes and other fruits), -carotene (7,8,7, 8 -tetrahydro- / V"carotenei yellow) and lyc.oxanthin ( /, /-caroten-16-0I yellow). 

Two fundamental building-blocks of natural product chemicals are isopentyl pyrophosphate and isoprene [31, 32], Isoprene is incorporated in compounds known as isoprenoids. The function and occurrence of isoprenoids cover a very broad range in nature according to Stryer [31], "-isoprenoids can bring delight by their colour as well as their fragrance. Indeed, isoprenoids can be regarded as the sensual molecules The colour of tomatoes and carrots comes from carotenoids, specifically lycopene and beta-carotene, respectively."... 

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