Betalaínas de Cactáceas, colorantes naturales con propiedades funcionales

NAZARENO, M. A .

Cartagena

Congreso; XII Congreso Colombiano de Fitoquímica; 2014

Universidad de Cartagena

In recent years, growing concerns about food safety and the strong consumer demands have induced many food manufacturers to review the formulation of their products and to make efforts to replace synthetic colorants by natural ones, when this is technologically feasible. Among the water-soluble natural pigments, betalains present significant advantages as they have good chemical stability in a wide pH range facilitating its application in low-acidic foods such as dairy products. These pigments can be obtained from cactus pear fruits. Our main aim was to evaluate the protective effect of cactus betalains against lipid oxidation when these compounds are added to yogurt and milk cream as functional natural colorants. Cactus pear fruits of the Opuntia genus from Santiago del Estero, Argentina, were collected in order to determine the profile of betalains of these fruits in order to find the best sources for obtaining betaxanthins and betacyanins that can be used to obtain food colorants. Betalains were purified from cactus fruits. Betacyanins and betaxanthins were extracted from Opuntia ficus-indica (purple pulp) and Opuntia megacantha (yellow-orange pulp), respectively; betanin and indicaxanthin being the major ones. Total betalain contents was determined by UV-Vis spectrophotometry (30-166 ug/g). Betacyanin and betaxanthin profiles were analyzed by HPLC-DAD. The betacarotene content was determined by HPLC to avoid interference from betaxanthins (0.60-1.70 ug/g) and provitamin A value was calculated. Free radical scavenging activities of the fruit extracts were measured using two methods: DPPH and ABTS radicals and results were expressed as ascorbic acid (VCEAC) and Trolox (TEAC) equivalents, respectively. The analyzed fruits are good sources of vitamins and antioxidants and they can be considered excellent alternatives to be incorporated into the diet. The fruits with the highest pigment levels were identified as the best sources to obtain the red and yellow pigments for food colouring and other purposes. Changes in the antioxidant activity and in bioactive substances contents in fruits and their alcoholic extracts stored at different storage temperatures for 6 weeks after harvest were analyzed. Different betalain concentrations were assayed in both foods. Food oxidation process was induced by a free radical generator azocompound (AAPH) in order to accelerate the reaction. Lipid oxidation products were determined by the method of thiobarbituric acid reactive substances (TBARS). This spectrophotometric technique measures the formation of final stage products of lipid oxidation taking as reference malondialdehyde (MDA). The control system consisted of food without pigment additions. The highest concentrations of betacyanin and betaxanthin to be assayed were selected considering pink and pale yellow color intensities similar to those of commercial strawberry and peach yogurts where synthetic colorants are regularly used. The results show that both kinds of pigments significantly reduced the lipid oxidation products formation compared to the system control. The effect increased, the higher the applied concentration. Betanin was more efficient than indicaxanthin protecting yogurt and cream from oxidation damages. Results indicate that cactus betalain can be used to replace the synthetic coloring food improving oxidative stability of food.