Research Of Lacticin LLC518and Sakacin LSJ618on The Preservation Of Bean Curd

Bacteriocins of lactic acid bacteria are efficient and non-toxic natural biologicalpreservatives, which are used to improve food preservation and safety. More andmore bacteriocins are used on the food industry in recent years, but the studies ofpreservation on bean products are few.In this paper, the research subjects were Lacticin LLC518and Sakacin LSJ618,which can inhibit the growth of some Gram-positive and Gram-negative bacteria. Theinhibitory effect was compared by different concentrations of lactobacillins and Nisin.And then further studied effects of lactobacillins and mixed formulations on thepreservation of bean curd.1. The samples of Lacticin LLC518and Sakacin LSJ618obtained by Spray-drying method under best factors of materials ratio, inlet and outlet temperature.2. By compared discipline of Lacticin LLC518, Sakacin LSJ618and Nisininhibited on Bacillus cereus, results showed minimum concentration of Nisin was0.1%, LLC518and LSJ618respectively were4%and1%.3. Three different strains isolated and purified from corruption bean curd by themethod of diluted and coated plate. Three strains were sprayed on the surface of freshbean curd, cultured for48h at37℃and results showed that three strains couldsignificantly speed up the corruption of bean curd as the main spoilage bacteria.4. Referred to―Berger Bacterial Identification Manual‖(Version8), and―Common Bacterial Systems Identification Manual", compared results showed thatdfl-1strains derived from the genus of Bacillus, the dfl-2from the genus ofPseudomonas, dfl-3from the genus of Streptococcus.5. Lacticin LLC518, Sakacin LSJ618and the mixture of the two lactobacillinswere evenly sprayed on the surface of bean curd. It was shown that all the threetreatments discussed above can stop the declination of sensory scores, slow down thegrowth of the total number of bacteria in bean curd and prolong the storage time ofbean curd. In addition, Lacticin LLC518could extend the shelf life of the storage ofbean curd to4days. Sakacin LSJ618could extend the shelf life to2days, and themixture of the two had a complementary effect.