CAROTENOID COMPOSITION OF A LEAFY VEGETABLE IN RELATION TO SOME AGRICULTURAL VARIABLES

Cultivar differences, seasonal variations, and farming practices on the carotenoid composition of a leafy vegetable (kale) were studied. Although the samples were taken from commercial farms, sampling was planned so that the effect of each factor could be assessed. The carotenoids and the vitamin A value were significantly higher in the cultivar Tronchuda in the summer; the same tendency was observed in the winter, but the differences were not statistically significant. The beta-carotene, lutein-violaxanthin, and total carotenoid levels, as well as the vitamin A value, were significantly higher in the winter than in the summer for cv. Manteiga kale. On the other hand, the neoxanthin content was significantly higher in the summer for the Tronchuda cultivar. All the constituent carotenoids were significantly higher in the samples from the "natural" farm as compared to those from the farm that used agro-chemicals.