Nano-silver Composite Agents On Preservation Of Nanfeng Citruses

Due to the prone disoperation of the Nanfeng mandarin caused by pathogens,how to break the fruit preservation technology is crucial for the promotion of thecommercial treatment and reduction of the post-harvest losses. In this study, wemixed the1%carboxymethyl chitosan,1%chitosan, and glycerine into a pure clearsolution, and then the pure clear solution was added to a certain amount of silver nanozirconia to formulate into nano-silver composite preservation agent. Firstly, we studythe different antibacterial effects of nano-silver, chitosan, carboxymethyl chitosan,and chemical preservatives on Penicillium and Aspergillus; and then, we analyzed thedifferences in the absorbance, membrane permeability, and bacteriostasis among thenano-silver composite plastic wrap, single-carboxymethyl chitosan film, and chitosan;lastly, the preservative effects were analyzed among the four groups to obtain the bestpreservation technology. The results are showed as follows:(1) In the antibacterial effect side, through the inhibition zone test, we found thatboth the chemical preservatives and the nano-silver have the better antibacterial effecton Penicillium, and the advantages and disadvantages order is: chemical preservatives> nano-silver. In addition, the our results showed that the inhibitory effect of nanosilver enhanced with the increasing concentration, but little change in inhibitoryradius. However, the edge inhibition zone of the chitosan and carboxymethyl chitosanwas not clear, and the antibacterial radius is almost zero. Moreover, as theconcentration of increases, the inhibitory effect of the chitosan and carboxymethylchitosan is not obvious.(2) In the absorbance and membrane permeability side, the order is: chitosan>nano-silver chitosan> carboxymethyl chitosan, which showed the transparency andmoisturizing effect of carboxymethyl chitosan were best. Both the chitosan andcarboxymethyl chitosan have antibacterial effects on Penicillium and Aspergillus, thatit could cut off the mold in contact with tangerine and reduce fungal infection leavingrotting.(3) In the preservative effect side, the results showed that the weight loss was lower in the preservative treatment groups than the control with higher total sugarcontent,Vc content, and total acid content, In the weight loss, the order iscarboxymethyl chitosan> nano-silver composite preservation> chitosan> chemicalpreservatiaon;In total sugar, the order is chitosan> nano-silver compositepreservation> carboxymethyl chitosan> chemical preservation; In total acid, theorder is nano-silver composite preservation> chitosan> carboxymethyl chitosan>chemical preservation; In Vc content, the order is nano-silver composite preservation> carboxymethyl chitosan> chitosan> chemical preservation.Our study indicatedthat there were best effects on preservation of Nanfeng mandarin by nano-silver composite preservation, and the film coating preservation is stronger than thechemical preservation.