| Consumer have been interested in natural preservative, and paid great attention to food preservative for lots of food safty problems in the past few years. The purpose of experiment is to search for a kind of natural and safe food preservative which can be used in preservation of chilled fresh pork. Lactoperoxidase System (LPS) is one of natural antibacterial activity system in fresh milk, that meet the demand of natural and safty. At the same time, the yield of milk serum as by-product has increased along with the development of china dairy industry and increase of cheese yield, so raw material of LP production is plentiful. In addition, chilled pork has been the main way of production, circulation and marketing of pork along with the improvement of living condition. So chilled pork treated with LPS satisfys the demand of market and is in conformity with the tendency of future, furthermore, the application of LP on chilled fresh pork is feasible in theory.Considering the antibacterial properties and generally recognized as safe (GRAS) status of LPS, some study of LPS were conducted in this paper:1 Using the method of gradient elution procedure for isolation and purification of lactoperoxidase from milk by strong cation exchange chromatography, In addition, lactoperoxidase was analyzed qualitatively and quantitatively by the use of SDS-PAGE and coomassie brilliant blue. That provided scientific evidence for isolation and purification of lactoperoxidase enzyme.2 The antibacterial action of lactoperoxidase was studied by spectrophotometric method, aperture pervasion method, and dry cell weight method in this paper. That provided experimental evidence for application of LP as preservatives.3 Researching the application of lactoperoxidase system on chilled pork preservation, compared with Nisin which is one of natural preservative that used widely in chilled pork preservation, observing the effect of LPS used in pork preservation.That provided a new way for chilled pork preservation.The results showed that:1 LP as a single band in SDS-PAGE, the molecular weight of LP was 76186D. The recovery of lactoperoxidase activity was 83.07%, and purification multiple was 103.33.2 Lactoperoxidase had a notable inhibition on seven species of food pollutant bacteria (Escherichia coli, Staphylococcus aureus,Bacillus subtilis,Pseudomonasaeruginosa,Aspergillus flavus,Penicillium chrysogenum and Saccharomyces cerevisiae),especially on Aspergillus flavus, the complete antibacterial concentration was 4μg/ml. Antibacterial action in neutral and low acid environment was stronger than antibacterial action in the high alkali environment. Antibacterial action of LP would not be affected in a certain temperature scope. Anti-G~-, anti-mold and anti-yeast fungus activities of LP were better than Nisin in natural pH, as well LP and Nisin had synergetic antibacterial action.3 when concentration of LPS is 3μg/ml and 4μg/ml shown a better preservative effect than Nisin of 40μg/ml if LPS and Nisin are used on chilled pork preservation separately, however, we got a better preservative effect when they both used.The study above made experimental basis for the further study of lactoperoxidase system as natural food preservative used in the whole food industry, and provided reliable experimental data for developing compound preservative which mainly consisted of LPS in the future.
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