Preparation Of Natamycin Nanoparticles/Chitosan Coating Preservative And Its Application In Sweet Cherry Preservation

Fungal infection is the main cause of sweet cherry decay during postharvest storage,which causes huge economic losses every year.Natamycin is a new kind of natural fresh-keeping agent,no poison to human body,has been listed in the catalogue of food additives in our country,suitable for fruit and vegetable fresh-keeping,but it is difficult to dissolve in water,therefore the development is hindered.Natamycin can be prepared into nanoparticles by nanotechnology to increase its solubility.Therefore,in this study,natamycin nanoparticles were prepared by the antisolvent method,and they were combined with chitosan to prepare natamycin nanoparticles/chitosan film,and the preservation effect of natamycin nanoparticles/chitosan film on sweet cherry was studied,and the following results were obtained:（1）The dispersion system of natamycin nanoparticles was prepared（Nata-NPS）.The influence of different proportions on Natamycin dispersion system was studied from particle size,Zeta potential,SEM and infrared spectrum scanning,etc.The solubilization effect of Natamycin dispersion system on Natamycin was reflected from the direction of antibacterial effect.The results showed that the prepared natamycin nanoparticles had a particle size of 209±10 nm,and their apparent morphology was uniform spherical structure.Infrared spectrum scanning proved that the nanoparticles had the original properties of natamycin,and bacteriostatic experiments showed that the bacteriostatic properties of natamycin nanoparticles were enhanced after the formation of natamycin particles,and the solubility of natamycin was increased to 1mg/m L.The Nata-NPS dispersion system was prepared,and the influence of different proportions on the Nata-NPS dispersion system was studied.The solubilization effect of the Nata-NPS dispersion system on natamycin was reflected from the direction of antibacterial effect.（2）Natamycin nanoparticles were prepared into membranes with chitosan,and the membrane properties of different amounts of natamycin nanoparticles were studied.The results showed that;The thickness of natamycin nanoparticles/chitosan film was kept between 0.16-0.2 mm.With the increase of natamycin nanoparticles,the thickness and color of natamycin nanoparticles increased,and the opacity showed a trend of increasing first and then decreasing.The best effect was achieved when the concentration of natamycin nanoparticles reached 1 mg/m L and the thickness was 0.2mm.The light permeability is 0.73%.The water vapor permeability of natamycin nanoparticle/chitosan membrane was 1.45×10-11 g m^-1s^-1Pa^-1,and the inhibition effect on fungi was the best at this time.The bacteriostatic ability of the membrane could not be improved by adding natamycin nanoparticle.（3）Sweet cherries were treated with natamycin nanoparticles/chitosan,chitosan and natamycin nanoparticles respectively,and no treatment was used as control group.Sweet cherries were stored for 35 days.The results showed that the coating treatment could delay the reduction of fruit weight,hardness,soluble solid（TSS）content and titratable acid（TA）content,reduce the decay rate of sweet cherry,maintain the brightness of fruit peel（L*）,improve the antioxidant capacity of fruit,delay the reduction of phenolic substances content,and improve the shelf life quality of sweet cherry.Inhibits the aging of sweet cherries.The results showed that natamycin nanoparticles/chitosan was more effective than chitosan and natamycin nanoparticles in preserving sweet cherry.