The influence of pH and enzyme cross-linking on protein delivery properties of WPI-beet pectin complexes

• Published in: Food research international 2018-03, Vol.105, p.678-685
• Main Authors: Wang, Qiang, Ren, Yanrong, Ding, Yangping, Xu, Minwei, Chen, Bingcan
• Format: Article
• Language: English
• Subjects: Biopolymer complexes; Complex coacervation; Complexation; FITC-BSA; Laccase; Release
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2017.11.076

The incorporation of bioactive proteins and peptides into food is associated with the loss of bioactivity due to deactivation in complex food matrices and in digestion systems. In this study, two different types of protein carriers, i.e. biopolymer complexation and complex coacervation were fabricated using whey protein isolation (WPI, 6wt%) and beet pectin (BP, 1.25 and 1.00wt%) at pH5.5 and 3.5, respectively. The release of the encapsulated FITC-BSA, a model bioactive protein, in both carriers in the absence and presence of laccase was investigated at both pH7.0 and 4.0. Release of FITC-BSA from both lyophilized WPI-beet pectin biopolymer complexation and complex coacervation were biphasic with an initial burst release followed by a slower release phase. The addition of laccase in biopolymer complexation increased the loading efficiency from 44.95% to 52.15% and slowed down the burst release of FITC-BSA but did change the biphasic release pattern. Laccase-cross linked WPI (6wt%)-BP (1wt%) complex coacervation had highest FITC-BSA loading efficiency (96.90%). The release of the embedded FITC-BSA in this carrier at both pH4 and 7 was in a gradual manner and the profile can be fit to zero order kinetics over the 72h study period suggesting enzymatically reinforced complex coacervation between the protein and the negatively charged beet pectin can restrain the burst release of FITC-BSA. These results indicate that laccase cross-linked WPI-beet pectin complex coacervation can be a good carrier system for delivering hydrophilic bioactive proteins or peptides successfully with enhanced loading parameters and sustained release profiles. Schematic representation of BSA delivery properties in WPI-beet pectin complexes. [Display omitted] •WPI and beet pectin formed complexation and complex coacervation under different pH.•Incorporation of significant amount of BSA within WPI-beet pectin network was allowed.•Gradual BSA release was achieved in laccase cross-linked WPI-beet pectin complex coacervation.•The physiological pH had limited impact on the release profile of BSA in WPI-beet pectin complexes.