The invention provides a fresh keeping agent, a preparation method thereof, and the application of the fresh keeping agent in fresh keeping treatment of dishcloth gourds. The fresh keeping agent comprises
chitosan, L-
cysteine,
cinnamic aldehyde and water, and the pH of the fresh keeping agent is 5.6-6.5. The
chitosan can form
semipermeable membranes on the surfaces of the dishcloth gourds, so that restraining the loss of water on the
cuticle of the dishcloth gourds is facilitated, and the depletion of substances in the dishcloth gourds is delayed; the L-
cysteine is beneficial to protecting the color of the
cuticle of the
dishcloth gourd, restraining the oxygenolysis of
cuticle chlorophyll and avoiding generating black spots; the
cinnamic aldehyde is beneficial to restraining the dishcloth gourds from infecting
pathogenic bacteria microorganisms during storage and restraining the dishcloth gourds from being decomposed; the
chitosan, the L-
cysteine and the
cinnamic aldehyde all contain functional groups which are easy to form
hydrogen bonds, so that when synergistic effects of the chitosan, the L-cysteine and the cinnamic
aldehyde are exerted, improving the compactability, the inoxidizability and the bacteriocidal property of the
semipermeable membranes formed on the surfaces of the dishcloth gourds by the chitosan is facilitated. The pH is controlled within the range, which is close to the autologous pH of the dishcloth gourds, so that further improving the fresh keeping effect of the fresh keeping agent is facilitated.