Health-promoting substances and antioxidant properties of Opuntia sp. fruits. Changes in bioactive-compound contents during ripening process

Several Opuntia cactus fruits of different pulp colours from Argentina were studied at their physiological mature states. Analyses of these fruits showed very variable total soluble solid values and ascorbic acid contents ranging from 0.26 to 0.48 mg/g. Total phenolic compounds contents were between 0.54 and 1.2 mg of gallic acid/g, respectively. Purple Opuntia spp., dark purple Opuntia ficus-indica and orange Opuntia megacantha presented the highest levels amongst the samples studied. The antioxidant activity of Opuntia fruits was very variable and presented vitamin C equivalent values (VCEAC) between 0.25 and 0.57 mg/g. Purple Opuntia ficus-indica showed the highest antiradical ability. Besides, the antioxidant activity, ascorbic acid and phenolic compound contents in yellow and orange Opuntia megacantha fruits were monitored in different stages during their ripening process. Concentration changes of betalains and chlorophylls comparing skin and pulp and other physicochemical parameters were also measured in these fruits.