Use of pennisetin-casein complex microparticles for Curcuma longa L. extract microencapsulation: Improvement of antioxidant and alpha-amylase inhibitory activities

Abstract

This study aimed to use a new protein complex of Pennisetin (Pen) a non gluten protein of pearl millet and casein (Cas), for curcumin (Cur) extract encapsulation using simple or complex coacervation. The potential improvement of Cur antioxidant activities and α-amylase inhibition after encapsulation was explored. Complex microparticles of Pen and Cas with various ratios exhibited average diameters ranging from 1.95 ± 0.32 to 4.66 ± 0.99 μm, whereas the Cur loaded microparticles had average diameters ranging from 2.50 ± 0.89 to 5.27 ± 1.17 μm. FTIR analysis of Cur loaded microparticles showed the presence of specific peaks at 3757, 1754, 1157 and 856 cm^-1 related to characteristic functional groups of Cur. This confirms the successful encapsulation of Cur. The major forces involved in microparticles formation were hydrophobic interaction and hydrogen bonding. The best encapsulation efficiency 68 % and loading capacity 17 % were obtained for the complex microparticles Pen:Cas (ratio 1:1.5). Encapsulating Cur within microparticles of Pen, Cas or their complexes significantly (p˂0.05) enhances their DPPH and ABTS^.+ antioxidant activities and their pancreatic α-amylase inhibition percentage. These findings shed light on the potential use of Pen a non gluten protein, in its native form or complexed with Cas, as wall material for hydrophobic or hydrophilic bioactive compounds encapsulation.

Keywords: Alpha-amylase inhibition, Curcuma longa extract; Antioxidant activity; Casein; Microencapsulation; Pennisetin.