Composition and contents of phytochemicals (glucosinolates, carotenoids and chlorophylls) and ascorbic acid in selected Brassica species (B. juncea, B. rapa subsp. nipposinica var. chinoleifera, B. rapa subsp. chinensis and B. rapa subsp. rapa )

Cultivars of selected Brassica species (B. juncea, B. rapa subsp. nipposinica var. chinoleifera, B. rapa subsp. chinensis and B. rapa subsp. rapa) showed significant differences in their composition and contents of phytochemicals and ascorbic acid. B. juncea was characterised by high proportion of alkenyl glucosinolates (85 to 96%) with a predominance of sinigrin; whereas in B. rapa subsp. nipposinica var. chinoleifera and B. rapa subsp. chinensis, the alkenyl glucosinolate proportion varied between 27 and 88% and consisted mainly of gluconapin, glucobrassicanapin and progoitrin. In B. rapa subsp. rapa, the main glucosinolate was the aryl glucosinolate gluconasturtiin (44 to 47%) with a relatively high level between 23.6 and 35.9 mg 100 g-1 FM. Distinct genotypic variations were also observed for lutein (3.4 to 8.9 mg 100 g-1 FM), 8-carotene (1.8 to 4.3 mg 100 g-1 FM) as well as chlorophyll a (35.7 to 96.8 mg 100 g-1 FM) and chlorophyll b (11.4 to 30.5 mg 100 g-1 FM). The cultivars 'Green Boy' (B. rapa subsp. nipposinica var. chinoleifera), 'Tatsoi' (B. rapa subsp. chinensis) and 'Green in Snow' (B. juncea) were rich in carotenoids (9 to 12 mg 100 g-1 FM) and chlorophylls (86 to 126 mg 100 g-1 FM). In contrast to other leafy vegetables tested, the Asian vegetables B. juncea, B. rapa subsp. nipposinica var. chinoleifera and B. rapa subsp. chinensis had relatively high ascorbic acid contents of between 49.2 and 89.1 mg 100 g-1 FM.