Fabrication Of Natamycin-loaded Zein-Casein Nanoparticles And Its Application In Edible Coatings And Films

As a safety natural preservative,Natamycin(NATA)can effectively and exclusively inhibits the growth of fungi and yeast and prevents food from spoilage.However,the water solubility and stability of NATA are poor,which limits its application in food and fruit preservation.In this study,a NATA-loaded zein/casein(CS)composite nanoparticle system(hereinafter referred to as NZCS)was prepared by green pH co-precipitation method.The application of NZCS as functional additives in edible coatings and films was explored.The main studies were as follows:Firstly,NZCS nanodispersion system was prepared by pH co-precipitation and its physicochemical properties were determined.The effects of different stabilizers and neutralizing acids on the preparation of zein nanoparticles by pH co-precipitation were investigated.The main preparation conditions of zein-CS nanoparticles were optimized with using CS as a stabilizer and phosphoric acid was used as the acid.The pH,ionic strength,storage stability,and redispersibility and SEM micromorphology of NZCS and NZ(without CS as stabilizer)were investigated.Compared with the NZ nanoparticle system,the NZCS nano-system has better colloidal stability between pH 2 and 7.Secondly,the antibacterial properties of NZCS against Monilinia fructicola were evaluated and its application in peach preservation as an antifungal coatings was investigated.The experimental results show that the apparent viscosity of NZCS nanocoating solution(0.5%~2%,w/v)is between 3-20 cP,showing the shear-thinning non-Newtonian fluid properties.On the surface of the peach,the contact angle of the coating liquid decreases as the concentration of NZCS increases(from 114.18° to 88.38°).Through the mycelial growth and spore germination experiments,the antibacterial properties of NZCS nano coating liquid on Monilinia fructicola were investigated.The inhibition rate of NZCS nano-coating solution increased with the increase of NATA concentration.The spore germination,the lesion in the NZCS nano-coating solution treatment group was 9.25 mm,which was reduced by two times,effectively controlling the expansion of the lesion.It couldinhibit the spore germination of peach Monilinia fructicola and effectively control the spread of disease spots.Finally,the effects of NZCS nanosystem on the physicochemical and bacteriostatic properties of gelatin composite films were studied.Based on the determination of its mechanical properties and water transparency value,the optimized preparation methods of the composite film were obtained.Compared with the pure gelatin film,the tensile strength of the NZCS loaded gelatin composite film was increased by 50%,the elongation at break was increased by 2 times.The ductility,the water resistance and the hydrophobicity were significantly enhanced.The NZCS loaded gelatin composite film also exhibited good inhibition properties against Aspergillus niger,Botrytis cinerea and Penicillium citrinum.