Abstract: This article selected tea polyphenols , Nisin, collagen proteinum, chitosan and so on to make a composite naturalfresh-keeping film, together with the vacuum packageing technique to carry out a research on presereing freshness of chilled beef.The indexes of the chilled beef,such as colony count, MPN, Aw,permeation rate,pH, meat tenderness, H2S and TVB-N wereassayed. Mainly, by means of TVB-N the final fresh degree was judged and fixed. The results showed: in group 3 and group 5of the experiment, the validity of the cooled beef was over 18d,in Comparison with 6d for control.Meanwhile, the validity of thecooled beef in group 5, was 21d, much longer than any other groups evidently.

Key words: chilled beef, tea polyphenols, Nisin, chitosan