Encapsulation of EGCG and esterified EGCG derivatives in double emulsions containing Whey Protein Isolate, Bacterial Cellulose and salt.

Double (W1/O/W2) emulsions of 0.8 %wt PGPR-0.25 %wt BC-1 %wt WPI and NaCl (1.6-8 %wt) were characterized regarding their microstructure, droplet size, stability and viscosity. Droplet size increased with salt concentration. Salt addition at 4-5% wt limited the instability rate. Viscosity increased with NaCl concentration up to 4.8 %wt, above which it decreased. Eventually, the emulsion with 4.3 %wt salt was selected for catechin incorporation. In order to increase its antioxidant activity, Epigallocatechin Gallate (EGCG) was esterified with stearic acid. Esterification was partial and a mixture of esters was obtained. Both EGCG and its esterified derivatives were incorporated in the double emulsion. Storage reduced encapsulation. Encapsulation efficiency was reduced in the order "EGCG in the W1 phase" emulsion > "EGCG in the O phase" emulsion > "esterified EGCG in the W1 phase" emulsion. The presence of both catechins did not have a great effect on retarding emulsion oxidation.

Bioactivity of Epigallocatechin Gallate Nanoemulsions Evaluated in Mice Model.

The hypothesis that incorporation of epigallocatechin gallate (EGCG) into nanoemulsions may increase its bioactivity compared with EGCG aqueous solutions was examined in mice. After an in vitro study in a model system with stimulated gastrointestinal conditions, the following EGCG nanoemulsions were used in a mice experiment: Emulsion I: emulsion water in oil (W/O), which contained 0.23 mg/mL EGCG in aqueous phase; Emulsion II: emulsion oil in water (O/W), which contained 10% olive oil and 0.23 mg/mL esterified EGCG in fatty phase; and Emulsion III: emulsion O/W in water (W1/O/W2; 8:32:60), which contained 32% olive oil and 0.23 mg/mL EGCG in aqueous phase. After 2 h of mice administration by gavage with 0.1 mL of EGCG nanoemulsions, total antioxidant capacity (TAC) of plasma and some tissues (especially colon, jejunum, heart, spleen) was measured with Ferric-Reducing Antioxidant Power (FRAP) and Oxygen Radical Absorbance Capacity (ORAC) assays. No toxic effects were observed after administration of 0.23 mg/mL esterified EGCG in CD1 mouse strain. The study concluded that administration of mice with the three EGCG nanoemulsions did not increase their TAC in specific tissues, compared with an aqueous EGCG solution at the same concentration. Nevertheless, the esterified EGCG emulsion (Emulsion II) exerted an increase in mice plasma compared with aqueous EGCG and showed higher values of TAC in several tissues, compared with Emulsions I and III. EGCG nanoemulsions could be considered a useful method in plethora functional food applications, but further research is required for safer results.