Anti-oxidant content of different coloured sweet peppers, white, green, yellow, orange and red (Capsicum annuum L.)

Five different coloured sweet peppers (Capsicum annuum cv. Signal), white, green, yellow, orange and red were analysed for total carotenoids, alpha-tocopherol, sugars (glucose, fructose and sucrose), organic acids (citric and ascorbic acids) and anti-oxidant properties. The mature fruits, 'Signal Red', 'Signal Orange' and 'Signal Yellow' contained higher carotenoids, alpha-tocopherol, sugars and organic acids than the immature fruits, 'Signal Green' and 'Signal White'. Among the mature fruits, 'Signal Red' was the highest in total carotenoids [9.15 mg (100 g)(-1) of fresh weight] while 'Signal Orange' was the highest in alpha-tocopherol [5.40 mg (100 g)(-1) of fresh weight]. 'Signal Red' and 'Signal Orange' contained the most sugars and organic acids. The suppression of 2,2'-azobis (2,4-dimethylvaleronitrile) (AMVN)-induced oxidation of methyl linoleate by the acetone extracts from the coloured sweet peppers resulted as follows: 'Signal Red' > 'Signal Orange' approximate to 'Signal Yellow' > 'Signal Green' approximate to 'Signal White'. The order of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities of the acetone extracts was similar to that of suppression of methyl linoleate oxidation.