Studies on Carotenoid Pigments and Colour of Fruits in Japan : Part V. On Reddish Carotenoids in Beni-unshiu Peels

The reddish carotenoids, existing in 13-20% or total carotenoids in the Beni-umshiu peels and contributing to its red color, were examined. The reddish carotenoids occured very closely in the position of violaxanthin (dioldiepoxide) on the magnesia column, and U_<476> and U_<464> (λ_<max> 476nm and 464nm in banzene) were separated as major pigments. On the magnesia column, U_<476> and U_<464> showed pink and reddish orange color, respectively. The properties of these reddish carotenoids were compared with reported carbonyl carotenoids by adsorption affinities, absorption maxima and shapes of spectra, eposide tests, isomerizations by I_2, and the changes of spectra and relative polarities before and after NaBH_4 reduction on keto group. As a result, U_<476> was considered as reticulatazanthin and U_<464> was supposed as carotenoid including nonnenone and two keto groups. On the procedure of purification, the other carbonyl carotenoid-like substance (λ_<max> 459 nm in benzene) was found, but was not identified on account of very small amount.(Received June 29, 1973)