Encapsulated Cactus Pear Betalains as Stabilized Food Colorant. Releasing Kinetic, Stability, Functional Properties and Uses in Foods.

OTÁLORA, M.C.; ITURRIAGA, L.; NAZARENO M. A.

Palermo

Congreso; VIII International Congress on Cactus pear and cochineal; 2013

Universitá de Palermo

Betalains are water-soluble pigments responsible for cactus pear fruit colors. Betalain health beneficial actions have been extensively reported. In consequence, their use as functional food colorants is a good option to replace synthetic ones. However, chemical stability is an important issue concerning the use of natural pigments as food colorants. It is affected by several factors during food processing and storage as well as after their application in a food matrix. The main aim of this study was to design and characterize capsules prepared using betalains extracted from cactus pear fruits (Opuntia spp.) to improve pigment stability and the subsequent controlled release in food systems. The capsules were prepared by ionic gelation method and extrusion technique. The process variables were established from defined concentrations of sodium alginate, ascorbic acid and calcium chloride. The capsules were prepared using extruder tips of internal diameter of 1.43mm presenting encapsulation performance efficiencies higher than 80% and sphericity degrees of 0.566±0.004. Pigment release to surrounding solutions presented kinetic behavior fitting a mathematical model adjustment according to Kopcha et al. (1991). The active agent release was ascribed to macromolecular relaxation after capsule swelling and pigment diffusion through the polymer which has undergone a process of erosion. Capsules were dried to 1.27% moisture content and stored at different water activities Aw (32.4-83.6) for 45 days. Significant differences in betalain concentrations and anti-radical activities were found, being more stable at low Aw. Furthermore, encapsulation improved pigment retention for betalain capsules stored in the dark under anaerobic conditions for 45 days; being higher at 4°C followed by 25 and 50°C. Un-encapsulated betalain was used as reference. A good correlation between pigment retention with antiradical activity was also found. The encapsulated pigment was applied in food matrix as jelly and color stability confirms its potential as a natural red colorant.