Encapsulation of polyphenols extracted from oat bran in a whey -zein protein-based biopolymer complex for enhanced bioactivity and bio accessibility

Encapsulation of polyphenols extracted from oat bran in a whey -zein protein-based biopolymer complex for enhanced bioactivity and bio accessibility.



Harthika Mylvaganama and Apollinaire Tsopmoa,b*

a Food Science and Nutrition Program, Department of Chemistry, Carleton University, Ottawa, ON, Canada.

b Institute of Biochemistry, Carleton university, Ottawa, ON, Canada.

An organic-solvent free pH-driven method was applied for the fabrication of nanoparticles composed of whey protein isolate (WPI) and zein protein at different ratios for the encapsulation of polyphenols extracted from oat bran (OBPP). The optimum ratio between WPI and Zein was determined by means of particle size, poly dispersity index (PDI), zeta potential and encapsulation efficacy (EE). According to the results, WPI: Zein ratio of 8:2 was selected as the most suitable ratio for further analysis as it showed favorable characteristics collectively such as low particle size (82.56 ± 0.11 nm), PDI (0.101 ± 0.00) and high zeta potential (-18.37 ± 0.27 mV) indicating high stability and narrow distribution and highest EE (86.29 ± 1.21 %). HPLC analysis of OBPP extract and PP encapsulates showed that the main polyphenols in the extract were ferulic acid and avenanthramides 2a, 2p and 2f. The bioactivity of the encapsulates were determined via ABTS assay. ABTS assay results showed that the proteins encapsulated polyphenols (PP-WPI-Zein) had significantly higher antioxidant activity (34.27 ± 0.11 %) compared to OBPP (12.91± 0.63 %) and WPI-Zein controls (20.99 ± 0.50 %). Further analyses are being carried out to assess the bio accessibility of the encapsulates.

Key words: Whey Protein Isolate, Zein protein, Polyphenols, Encapsulation, Bioactivity