Cactus betalains can be used as antioxidant food colorants protecting food constituents from oxidative damage.

CORIA CAYUPÁN, Y. S.; NAZARENO M. A.

ACTA HORTICULTURAE

INTERNATIONAL SOCIETY FOR HORTICULTURAL SCIENCE

Lugar: Palermo; Año: 2015 vol. 1067 p. 319 - 325

0567-7572

In order to find the best sources to obtain betaxanthins and betacyanins to be used as food colorants, some Opuntia fruits from Santiago del Estero, Argentina, were analyzed. Opuntia megacantha (orange and yellow pulp), Opuntia spp. (purple pulp) and Opuntia ficus-indica (purple and pink pulp) were collected to determine their betalain profiles. Secondly, bioactive compounds responsible for the health beneficial properties such as pigments, polyphenols and vitamins were characterized as well as the free radical scavenging activity of mature Opuntia fruits. Cactus fruits were brought to the laboratory, cleaned and analyzed immediately after harvest. Results showed highly variable values among the different species studied and even within the same species taking different colored fruits. Total soluble solids varied between 7.5 and 12.6 °Brix. Vitamin C contents (considering ascorbic acid and dehydroascorbic as vitamers) were determined by HPLC (0.22-0.71 mg/g). The total phenolic contents were measured by Folin-Ciocalteu method and ranged between 0.19 and 0.47 mg GA/g. The ascorbic acid interference was significant; therefore, this contribution was discounted. Total betalain contents in Opuntia fruits was determined by UV-Vis spectrophotometry (30-166 µg/g). Betacyanin and betaxanthin profiles were analyzed by HPLC-DAD. The betacarotene content was determined by HPLC to avoid interferences from betaxanthins; provitamin A value was calculated. Low levels of the lipophilic pigment were found (0.60-1.70 µg/g). Free radical scavenging activities of the fruit extracts were measured using DPPH and ABTS radical bleaching methods and results were expressed as ascorbic acid (VCEAC) and Trolox (TEAC) equivalents.