Anthocyanin-beta-lactoglobulin nanoparticles in acidic media: synthesis, characterization and interaction study

Abstract

This study aims to investigate the preparation, characterization, interaction binding, and application of β-Lactoglobulin (β-Lg) based nanoparticles for encapsulation of anthocyanins (AC) extracted from red raspberry pomace, systematically. We used anti-solvent method that is common for nano particle preparation of water-soluble proteins. Nanoparticles were fabricated by dissolving β-Lg in an alkaline base at pH 7 and heat treatment 85 °C with the aid of anti-solvent process using N-(3 dimethylaminopropyl)-N-ethyl carbodiimide hydrochloride (EDC) as a cross-linking, then AC was loaded on β-Lg nanoparticles using citrate buffer pH 3. The results showed that the mean particle size of β-Lg and AC-β-Lg ranged from 199 to 172 nm with a semi-spherical morphology revealed by scanning electron microscopy (SEM). Interaction results showed that AC (1, 2, 4, 6 and 8 × 10−4 M) quenched the fluorescence intensity of β-Lg by 97%, and binding occurred with a Ka value of 9.39 × 102 M−1 at 298 K via electrostatic forces. The β-Lg nanoparticles enhanced the bioavailability of AC was 22 %, which is higher than unencapsulated AC. Furthermore, the AC-loaded β-Lg nanoparticles were more stable in mouth (pH 6.8), simulated gastric (SG, pH 2), and simulated intestinal (SI, pH 6.9) by showing high retention rate (%) than free AC extract. These results may contribute to a better understanding of the improvement of AC bioavailability using β-Lg-nanoparticles.