Development of functionalized microparticles containing anthocyanins from grape extract (Vitis Labrusca L.) obtained by ionic gelation: evaluation of stability, controlled release and potential use as a colorimetric indicator

Abstract

In recent years, the food industry's search for natural bioactive compounds to produce multifunctional microparticles capable of coloring foods and providing real-time information about their freshness status has increased significantly. In this context, the aim of this work was to produce microparticles functionalized with anthocyanins extracted from grape skins, using the combined methods of emulsification and ionic gelation with ultrasound, in order to use them as food colorants and to monitor the quality of in-natura milk. In the first phase of the project, different gelling agents (alginate and pectin) were studied for the formation of multiple emulsions and their influence on the physicochemical and morphological properties, as well as on the gastrointestinal release profile of the microparticles. In general, the effect of emulsification combined with gelation was more pronounced in the alginate microparticles and resulted in greater retention of anthocyanins, greater antioxidant capacity, and also allowed the best release profile during intestinal digestion. Based on the choice of the best gelling system, different complementary wall materials were incorporated (modified starch, inulin and maltodextrin) to optimize the retention of bioactive compounds in the microparticles. In addition, the microparticles produced in the second phase were used in the form of a natural dye in milk to monitor the quality of the product and act as edible colorimetric indicators. The microparticles combined with modified starch were more stable under accelerated and thermal conditions compared to the microparticles containing inulin and maltodextrin, and retained the bioactive compounds better. Moreover, anthocyanin based microparticles were able to discriminate between fresh milk and milk unfit for human consumption. These results show us the possibility of using these smart microparticles as edible colorimetric indicators, opening up new approaches in the food industry and allowing consumers to tell with the naked eye whether the food is suitable for consumption or not, as well as being a natural colorant obtained from low-cost sources.