CAROTENOIDS 



(iv) Other Factors. There is only one report, which is, however, very 

 fully documented, that demonstrates that variation in mineral nutrients 

 of the soil has no effect on the carotenoid content of tomatoes. ^ » * 

 Similarly, treatment with ^-naphthoxyacetic acid produces no alteration 

 in carotene content. ^ ^ * 



SEED CAROTENOIDS 



In this section a wide interpretation of the term ** seed '* is accepted, 

 for a discussion of various grass and cereal " seeds," which strictly 

 are fruit, will be included. 



Apart from the yellow maize which will be dealt with separately, 

 grass and cereal seeds contain only small amounts of carotenoids in 

 which xanthophylls predominate ; no specific carotenoids have been 

 detected ; the pigments occur in both the flour and the bran. ^ 2 



Cereals such as wheat and rye contain between 130 and 150 [ig. per 

 cent, (wet wt.) of carotenoids of which about 10 per cent, is 

 carotene. '^ ^ ^" '^ '^ ^ The greatest carotene accumulation occurs at the 

 "milky" ripeness stage. ^^^ Underwood and Curnow, 225 report 

 values of 800, 900 and 1,000 [ig. per cent, (dry wt.) for wheat, oats and 

 barley carotenoids respectively, but these diflFerences are not considered 

 significant. Milling and processing destroy a considerable portion of 

 the carotenoids, e.g., whole wheat flour contains about 10[jLg. per cent, 

 of carotene and 150-200 [ig. per cent. 226. 227 (^jj-y weight) of xantho- 

 phylls ; similar values are reported for rye, barley, and blue vetch 

 flour. 228 The very low value for carotene in wheat flour has been 

 confirmed by Goodwin and Morton, 2 2» and Malmberg and von 

 Euler23o actually found no carotene in Swedish flour. Zechmeister 

 and Cholnoky22« j^^ve listed early reports on the carotene content of 

 flour and discuss reasons why, in these investigations, the carotene 

 present was over-estimated. 



Brockmann and Volker's^^i values for the carotene and lutein 

 (xanthophyll) of a number of grass seeds used in avian nutrition (see 

 Appendix I) are of the same order as those found for wheat, but it should 

 be noted that, contrary to Brockmann and Volker's observations, 

 Kritzler ^ 3 2 reports ^-carotene in canary grass and, rather oddly, only 

 oi-carotene in millet. A further interesting point is that arils of the seeds 

 of the passion flower {Passiflora coerulea) contain only lycopene. 2*3 

 Carotenoids have also been reported in seeds of Acer, Ginkgo, and 

 Citrus nohilis ^ ^ * and in coflFee beans. ^ ^ 6 



The xanthophyllic fraction from seeds is heterogeneous and Strain ^ ^ 

 believes that its composition is very similar to that from green leaves ; 



42 



