Construction And Antibacterial Properties Of Phosphorylated Egg White Protein Colloidal Particles For Delivery Of Cinnamon Essential Bark Oil

Cinnamon bark essential oil(CBO)has excellent antibacterial properties,but its application is limited by its volatility,sensitivity to environmental conditions(e.g.oxygen,light and heat),strong aroma and low water solubility.Previous research has shown that egg white proteins(EWP)can form nanoparticles under combined acid/heat induced sonication conditions and can effectively encapsulate essential oils and enhance their solubility,stability and antibacterial activity.To further enhance the application potential of EWP colloidal particles,this study applied phosphorylation modification technology and ultrasonic nanotechnology to construct phosphorylated egg white protein(P-EWP)colloidal particles,investigated the effects of phosphorylation modification on the structural and functional properties of EWP colloidal particles and CBO-loaded EWP colloidal particles,and evaluated the application of P-EWP colloidal particles as CBO-Pickering emulsion stabilizers.Pickering emulsion stabilizers.The main findings and conclusions of the study are as follows.(1)P-EWP colloidal particles were prepared,and the effects of phosphorylation modification and pH conditions on the formation and functional properties of EWP colloidal particles were investigated.The results showed that phosphorylation modification at pH 7-10 significantly enhanced the hardness,elasticity,adhesive and water-holding properties of EWP gels by 16.5%-1027.8%.The main driving forces for the formation of EWP colloidal particles and P-EWP colloidal particles were hydrophobic interactions and hydrogen bonding,and the phosphorylation modification at different pH conditions showed different degrees of influence on the strength of the forces and pellet dispersion of EWP colloidal particles;compared with EWP colloidal particles,the emulsification activity and emulsion stability of P-EWP colloidal particles were increased by 25.5-52.9%and The emulsification activity and emulsion stability of P-EWP colloidal particles increased by 25.5-52.9%and 15.6-61.1%,respectively,compared with EWP colloidal particles,with the emulsion stability increasing with pH.The above results indicate that the P-EWP colloidal particles formed under neutral and alkaline pH conditions have more stable structures and stronger emulsification properties.(2)CBO-loaded P-EWP colloidal particles were prepared and the effect of phosphorylation modification on the formation and bacterial inhibitory properties of the composite protein colloidal particles was investigated.P-EWP-CBO colloidal particles were well dispersed at an oil-to-wall ratio of 1:7,a reaction system pH of 8 and a protein concentration of 6.3%,with the encapsulation rate,particle size and PDI of 93.8±1.9%,133.6±0.8 nm and 0.265±0.01,respectively.The results showed that the phosphorylation modification changed the secondary and tertiary structures of EWP,and the introduction of P-O and P=O bonds improved the thermal stability of EWP gels and effectively contributed to the encapsulation of CBO;the inhibition experiments on Escherichia coli CICC 10664,Staphylococcus aureus CICC 21600 and Listeria monocytogenes ATCC 1911.The results showed that the MIC values of P-EWP-CBO colloidal particles were 2-fold lower than those of EWP-CBO colloidal particles for both bacteria,and the growth of pathogenic bacteria was completely inhibited within 108 h.Stability tests(30-90?/0-200 mM NaCl)showed that PEWP-CBO colloidal particles were more environmentally tolerant than EWP-CBO colloidal particles.3.P-EWP colloidal particles(PEN)/cellulose nanofibres(CNF)stabilised CBOPickering emulsions were prepared and the stability and antibacterial properties of the constructed emulsions were evaluated.The results of the emulsion stability tests showed that the combined CNF and PEN stabilised CBO-Pickering emulsions had better storage stability than the single CNF or PEN stabilised CBO-Pickering emulsions.The CNF-PEN stabilized Pickering emulsions obtained by secondary emulsification of CNF(1%)followed by PEN(2.5-20 mg/mL)achieved over 93.7%encapsulation of CBO with particle sizes ranging from 218.0 ± 0.4 nm to 408.8 ± 26.6 nm and zeta potentials ranging from-28.3 ± 0.2 mV to-37.2± 0.2 mV.Optical microscopy and confocal laser scanning microscopy showed that the CNF-PEN(2.5 mg/mL and 15-20 mg/mL)based emulsion droplets were round,well defined,small and uniformly distributed,while confocal laser scanning microscopy showed that all CNF-PEN(2.5-20 mg/mL)based emulsions were effective in encapsulating the oil droplets.The MIC values of CNF-PEN(2.5-20 mg/mL)based emulsions against Escherichia coli CICC 10664 and Staphylococcus aureus CICC 21600 were 0.2-0.4 mg/mL and 0.2-0.8 mg/mL respectively,with CNF-PEN(10 mg/mL and 15 mg/mL)based the emulsions showed MIC values of 0.2 mg/mL for both bacteria,which were 2.5 and 5 times lower compared to CBO,respectively.In conclusion,the phosphorylation modification under neutral and alkaline pH conditions effectively enhanced the stability and emulsification performance of the EWP colloidal particles;the constructed P-EWP-CBO colloidal particles and the CNF-PEN stabilized CBO-Pickering emulsion both had good stability and antibacterial properties,providing technical support for the combined application of egg white protein and cinnamon essential oil in the food and pharmaceutical industries.