A new way of valorizing biomaterials: The use of sunflower protein for α-tocopherol microencapsulation

- Sunflower protein (SP) is a new biopolymer with interest to use in encapsulation.
- Enzymatic hydrolysis resulted in proteinic macromolecules size decrease.
- Protein N-acylation increases its affinity with hydrophobic core material.
- N-acylation of SP improves retention efficiency of a-tocopherol.
- SP based microparticles can be loaded with hydrophobic core material up to 79.2%.

Biopolymer based microparticles were efficiently prepared from sunflower protein (SP) wall material and α-tocopherol (T) active core using a spray-drying technique. Protein enzymatic hydrolysis and/or N-acylation were carried out to make some structural modifications to the vegetable protein. Native and hydrolyzed SP were characterized by Asymmetrical Flow Field-Flow Fractionation (AsFlFFF). Results of AsFlFFF confirmed that size of proteinic macromolecules was influenced by degree of hydrolysis. The effect of protein modifications and the influence of wall/core ratio on both emulsions and microparticle properties were evaluated. Concerning emulsion properties, enzymatic hydrolysis involved a decrease in viscosity, whereas acylation did not significantly affect emulsion droplet size and viscosity. Microparticles obtained with hydrolyzed SP wall material showed lower retention efficiency (RE) than native SP microparticles (62-80% and 93% respectively). Conversely, acylation of both hydrolyzed SP and native SP allowed a higher RE to be reached (up to 100%). Increasing T concentration increased emulsion viscosity, emulsion droplet size and microparticle size, and enhanced RE. These results demonstrated the feasibility of highly loaded (up to 79.2% T) microparticles.