In vitro digestibility of gellan gels loaded with jabuticaba extract: Effect of matrix-bioactive interaction.

Abstract

Jabuticaba is a native Brazilian fruit rich in phenolic compounds as anthocyanins, showing several benefits for human health but a high sensibility to physicochemical digestion conditions. Gellan is a biopolymer that could be used as a material to protect and carry bioactive compounds, since this polysaccharide is resistant to gastric pH conditions. In this context, gellan gels containing jabuticaba extract were produced using two different ionic strength values (adding calcium ions), which resulted in varied structures. These gels were subjected to two different in vitro digestion processes, modifying the type of mechanical forces applied to simulate stomach and intestine movement conditions. Anthocyanins release (by pH differential method), mechanical properties, confocal and light microscopy of gels were evaluated during in vitro digestibility. Results showed that jabuticaba extract exerted effect on gels mechanical-structural properties, since an increase of stress at rupture (hardness) and a decrease of strain at rupture (deformability) were observed only in gels without calcium addition. Although all gellan gels have improved anthocyanins retention during simulated gastrointestinal digestion process, gels without calcium were more efficient. Our results demonstrated that gellan gels could act as good carriers for anthocyanins, but their efficiency is dependent on the matrix composition, demonstrating that specific studies should be accomplished to determine which changes may occur in the matrix after bioactive addition. Furthermore, our results showed that the type of mechanical forces applied during in vitro digestion is an important variable, since the use of compression (a more similar-to-in vivo system) rather than shear forces increased the release of anthocyanins.