Evaluation of alginate-biopolymers (protein, hydrocolloid, starch) composite microgels prepared by the spray aerosol technique as a carrier for green tea polyphenols

Effects of low methoxyl pectin, milk protein concentrate (MPC), and waxy starch on the encapsulation of green tea-polyphenols in alginate gels produced using spray aerosol technique were evaluated. MPC and waxy starch treated first by cold-renneted induced gelation method and gelatinization method, respectively. DSC thermal analysis and FTIR spectroscopy were used to prove the presence of polyphenols in gel matrixes. The encapsulation efficiency (%EE) and the polyphenols release were investigated using Folin-Ciocalteu assay. The results showed that the addition of biopolymers into alginate gels increased the encapsulation efficiency (%EE) but reduced the release percentage of polyphenol in water and simulated gastric fluid (SGF). Among the three biopolymers, cold-renneted MPC gave the best protection for polyphenols encapsulated in alginate microgels. It increased %EE from 63% to 68% in fresh gels, reduced the release percentage in water from 72% to 62% and reduced the release percentage in SGF from 76% to 67%.