CAROTENOIDS 



of Pyracantha coccineUy only small amounts of carotenoids are present. ' ' 

 However, [3 -carotene (together with small amounts of its m-isomers) is 

 the only carotene present in Badami mango fruit, ^ ' and in a number 

 of other varieties of mango this and lutein (xanthophyll) are the pre- 

 dominant pigments. » 8- 1 o 2 According to the variety, p-carotene 

 represents between 36 and 53 per cent, of the total carotenoids pre- 

 sent. ^ ® ^ In Pyracantha angustifolia ^-carotene is a major constituent 

 of the pigment fraction which only contains very small amounts of 

 xanthophylls ; "^ * a similar situation is reported in buriti palms, ^ ^ * 

 elderberries, ^ ** * dates, ^ ® * melons, ^^''^"'"^ beach plums, ^ ° ^ and cannon- 

 ball fruit. * ^ * According to Webster, Black and Cross ^ ^ " Concord are 

 the best variety of grapes from the carotenoid point of view. The 

 avocado pear appears to have a carotenoid distribution similar to green 

 leaves, for it contains 2-5 (J-g./g- of total carotenoids, of which 0-6 [xg. 

 is carotene. 10 per cent, of this carotene is the a-isomer. ^^^ 

 Papayas, * ^ ^ guavas ^ ^ ^ and the berries of Ruhus chamaemorus ^ ^ ^ also 

 contain p-carotene. It is interesting to compare the ^-carotene content 

 of fruit with the leaves of the plant producing the fruit ; rose hips 

 {Rosa cinnamomea and R. rugosa) grown in Russia contain 5 mg. per 

 cent, (wet wt.) compared with a value of 40 mg. per cent, found in 

 the corresponding leaves. ^ ^ * Apart from these comparatively few 

 examples p-carotene is not normally the major carotene in fruit, for 

 either a-carotene, y-carotene, or lycopene is the most common fruit 

 carotene. Further details concerning the carotene content of fruit are 

 given in the appendix (p. 294). 



(ii) oL'Carotene, although not a distinctive fruit carotenoid, generally 

 occurs in greater amounts, both absolutely and in relation to (3 -carotene, 

 than it does in leaves. It constitutes up to 40 per cent, of the total 

 pigment in red palm oil, ^ ^ '^ 25 per cent in banana flesh, ^ ^ « 25 per cent, 

 in the chestnut, ^ ^ '^ and 15 per cent, in the rowan berry (Sorbus aucu- 

 paria). ^ ^ ' Red palm oils are probably the richest sources of a-carotene 

 known, but other palm oils, e.g., Attalea gomphococca Mart, contain 

 much less ; apparently carotenes only are present in the latter oils. ^ ^ * 



(iii) -^-carotene was first isolated in 1932 from the fruit of the lily 

 of the valley (Convallaria majalts) by Winterstein and Ehrenberg ; ^ ^ " 

 the former investigator also demonstrated its presence in the fruit of 

 Gonocaryum pyriforme. ^ ^ « The Kuhn 1 2 1. 1 2 2 ^nd Karrer ^ 2 3 schools 

 soon afterwards elucidated its structure ; it is a monocyclic carotenoid 

 containing a [3-ionone and a t);-ionone residue. 



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