Kinetics of immobilisation and release of tryptophan, riboflavin and peptides from whey protein microbeads

• As molecule hydrophobicity increases, %encapsulation increases and %release decreases.
• Rate of encapsulation and release is not influenced by volume ratio.
• The more hydrophobic the compound, the slower the rate of release from the microbeads.
• Compound release is a process of partitioning between the bead and release medium.

This study investigated the kinetics of immobilisation and release of riboflavin, amino acids and peptides from whey microbeads. Blank whey microbeads were placed in solutions of the compounds. As the volume of microbeads added to the solution was increased, the uptake of the compounds increased, to a maximum of 95% for the pentapeptide and 56%, 57% and 45% for the dipeptide, riboflavin and tryptophan respectively, however, the rate of uptake remained constant. The rate of uptake increased with increasing molecule hydrophobicity. The opposite was observed in the release studies, the more hydrophobic compounds had lower release rate constants (kr). When whey microbeads are used as sorbents, they show excellent potential to immobilise small hydrophobic molecules and minimise subsequent diffusion, even in high moisture environments.