Behavior of whey protein aggregates-alginate beads filled with astaxanthin and chia oil during in vitro digestion

Abstract

The addition of whey proteins to alginate beads can enhance the functionality of encapsulation systems and improve the stability of the encapsulated bioactive compounds. In this work, chia oil (rich in omega-3 fatty acids) and astaxanthin were encapsulated in alginate (100SA) and whey protein aggregates-alginate (25WPA75SA) beads. The behavior of both types of beads during gastrointestinal digestion was assessed using the standardized INFOGEST in vitro methodology. Different mathematical models were used to analyze the release profile of the encapsulated bioactive compounds. Both types of beads protected the bioactive compounds during the gastric phase with release percentages lower than 10% and allowed their release during the intestinal phase with release percentages of up to 90%. The addition of whey protein aggregates did not affect the amount of bioactive compounds released. Furthermore, Korsmeyer-Peppas model showed a highly accurate fit and the release coefficient (k) values indicated a higher release rate of the bioactive compounds from 25WPA75SA beads (25WPA75SA beads: k = 9.18 × 10−4 s−n and k = 1.07 × 10−3 s−n, 100SA beads: k = 3.80 × 10−5 s−n and k = 2.20 × 10−5 s−n, for astaxanthin and omega-3 release, respectively). On the other hand, encapsulation slightly increased the chia oil lipolysis, but no differences were found between both types of beads. Finally, the bioaccessibility of both bioactive compounds were not influenced by the addition of whey protein aggregates. Practical applications: Chia oil (source of omega-3 fatty acids) and the pigment astaxanthin are valuable bioactive compounds for the formulation of healthy foods. The encapsulation system developed combining sodium alginate and whey protein aggregates allowed the protection of the bioactive compounds during gastric digestion and their controlled release during intestinal phase. Our findings show a promising strategy that can be satisfactorily used to deliver lipophilic active compounds.