Application of high-performance liquid chromatography to the characterization of the betalain pigments in prickly pear fruits

The qualitative and quantitative betalain pigment content of two cultivars of prickly pear (Opuntia ficus-indica) fruits grown in southeastern Spain was evaluated. After methanolic extraction of crushed fruits, reversed-phase high-performance liquid chromatography and photodiode array detection were applied simultaneously for the separation, identification and quantification of these pigments. Two main pigments were obtained, which were identified as indicaxanthin (λmax 484 nm) and betanin (λmax 535 nm). Spectrophotometric evaluation of both pigments showed a yield of around 20–30 mg per 100 g of fresh pulp. When the influence of temperature (25 to 90°C) on betacyanin pigment stability was investigated, the results revealed a substantial degree of thermodegradation at temperatures higher than 70°C.