Comparative study of the encapsulation of betaxanthins (opuntia megacantha) by spray drying and ionic gelation

OTÁLORA, M.C.; CARRIAZO, J.G.; ITURRIAGA, L.; OSORIO, C.; NAZARENO M.A.

Coquimbo

Congreso; IX International Congress on Cactus Pear and Cochineal; 2017

International Society for Horticultural Science

Betalains obtained from cactus pear fruits can be used as food colorants to replace artificial ones; being pigment stability one of the technological issues to be solved. Two different encapsulation technologies, spray drying (SD) and ionic gelation (IG), were evaluated as stabilization strategies for betaxanthins (BX) extracted from orange pulp fruits of Opuntia megacantha. Maltodextrin combined with cladode mucilage was used as SD encapsulating agent; while, calcium alginate was assayed as IG matrix comparing with freeze-dried fruit pulp (CP) as control. SD microcapsules and IG capsules containing cactus BX were prepared and characterized by analyzing total pigment contents and composition (HPLC-MS) as well as color parameters (CIELab). Encapsulation efficiency (%EE) was measured. Moisture content, water activity (aw), particle sizes and morphology, glass transition temperature, thermogravimetric properties and total dietary fiber contents were also evaluated in both types of capsules. Besides, radical scavenging activity retention and stability of the encapsulated pigments under different storage temperatures and relative humidities were studied. Results showed that the encapsulation technique, the encapsulating agent concentration and the BX/encapsulating agent ratio strongly influenced the particle properties. The antioxidant capacity was proportional to betalain contents in the capsules. A higher dietary fiber content was found in the SD and IG capsules due to the presence of mucilage and alginate in the matrix, respectively, than CP. The best results in terms of BX stabilization were obtained for SD capsules, although both encapsulation techniques led to improved pigment stability, especially under dry conditions in contrast to CP. The hydrolysis pathway was the main degradation mechanism and betalamic acid was the major product formed after storage. Encapsulated BX has the potential to be used as natural pigments, soluble in water, with functional properties for the food industry.