Direct microencapsulation of an annatto extract by precipitation of psyllium husk mucilage polysaccharides

Abstract

This work evaluates the use of a hydrocolloid extracted from psyllium husk as an encapsulating agent of an annatto extract. Psyllium mucilage was water extracted, whereas the annatto extract was prepared by mixing annatto seeds with different solvents in the proportion of 1: 4 (seed: solvent). The bixin composition was determined via HPLC, and the extract with the highest content was selected for microcapsule production. The extracted gel was stirred for 10 min with an ethanolic solution of bixin extract (0.25 g L−1) with a 100:75 mucilage volume to solution ratio to produce the microcapsules. FT-IR and FT-Raman spectroscopies were used to assess the interaction between extract and mucilage. The stability was evaluated by thermal analysis, high temperature exposure and constant luminosity exposure tests. Further, the microcapsules' performance was tested in a food system. The ethyl acetate extract presented the highest bixin content (8.56%) and its capsule displayed a bixin content of 4.05%. The microencapsulation efficiency was confirmed by the spectrograms and the microcapsules presented higher thermal stability when compared to the annatto extract. Finally, the use of microencapsulated extract in ice cream formulation improved color homogeneity and provided a superior emulsion stability over product's shelf life.