Fabrication of curcumin encapsulated in casein-ethyl cellulose complexes and its antibacterial activity when applied in combination with blue LED irradiation

Casein and ethyl cellulose (Cas + EC) complexes were fabricated and used for encapsulation of curcumin (Cur). Physicochemical properties of Cas + EC/Cur along with its antibacterial activity when used in combination with blue LED irradiation were investigated. Encapsulation efficiency of microparticles at Cas:EC of 1:1 was the highest at 92.4%, with average particle size of 1.47 μm and ζ-potential of −21.40 mV. Fourier transform infrared spectroscopy revealed that Cur was well encapsulated in Cas + EC by electrostatic interactions; more hydrogen bonds were also formed. At optimal encapsulation condition, Cur exhibited good thermal stability; its water solubility improved 69 folds, while its release rate in oily food mimic reached 76%. Cas + EC/Cur in combination with blue LED irradiation could rapidly inactivate Escherichia coli ATCC 43894, Staphylococcus aureus ATCC 23235 and Pseudomonas aeruginosa MCC-208. Such desirable activities are attributed to the production of reactive oxygen species, which caused increased membrane permeability and reduced bacterial cell integrity.