Encapsulação de extrato de beterraba por gelificação iônica utilizando emulsões múltiplas

Abstract

Beetroot (Beta vulgaris L.), a tuberous root vegetable belonging to the Quenopodiaceae family (Chenopodiaceae), is one of the main vegetables grown in Brazil. In addition, beets have considerable amounts of betalains, compounds that are recognized for their functional activity. Encapsulation processes contribute to the protection and controlled release of bioactive compounds. The ionic gelation technique is an option for carrying bioactive compounds and the combined use with double emulsions, also called multiple emulsions, provides improvements in the efficiency of the encapsulation process of hydrophilic compounds in these encapsulation systems. The objective of this work was to use ionic gelation, using alginate, as a microencapsulation method aiming at carrying and protecting the betalains present in the beetroot extract. Initially, different formulations of emulsions were tested, with varying concentrations of beet extract and soy oil, and the one considered the most stable and with the highest extract content was chosen for the continuation of the work. The emulsions had a regular and uniform spherical shape. The microspheres were produced with the following proportions of emulsion:alginate solution (%w/m): 20:80 (X1), 30:70 (X2) and 50:50 (X3). The encapsulation efficiency values obtained were 97.9%, 93.9% and 75.8%, respectively. The release profile of encapsulated betalains was evaluated over time in aqueous media with different pH (pH=4 and pH=10). Differences were observed between treatments and it was found that there was greater release when exposed to more acidic media. The stability of the betalains present in the beet extract at 25±1°C was evaluated for 30 days. It was possible to observe reductions in the betalain content of 94.8% (X1), 91.3% (X2) and 94.3% (X3) after 30 days. It can be concluded that it was possible to encapsulate betalain from the beetroot extract. Among the samples, the X2 treatment showed better morphological characteristics, with a more regular and uniform shape. In the stability study, there was a considerable loss of betalains over time, requiring the application of other strategies to maintain higher levels of betalains. Treatment (X1) showed less loss over time. Microencapsulation using alginate, combined with the use of multiple emulsions, can be considered an effective strategy for encapsulating hydrophilic bioactive components.