The Application Of Bacteriocin JL-A65 Produced By Lactobacillus Plantarum In Food Preservation

Lactic acid bacteria is recognized as safe food-grade micro-organisms at home and abroad.Bacteriocin is a class of peptides or precursor polypeptides produced by ribosome synthesis in the process of metabolism.It has a wide range of antibacterial spectrum.With the chemical preservatives caused by food safety problems become increasingly prominent,natural safety and antimicrobial substances in the application of food is increasingly important,At present,more and more natural preservatives are applied to food preservative.A new type of plantarum JL-A65 was isolated from farm pickles in Jilin Province.The plantarum JL-A65 was added to the cheese in the form of adjunctive starter,and the fermentation process was studied.The effect of bacteriocinJL-A65 on E.coli in fruit and vegetable juice was investigated,and the effect of bacteriocinJL-A65 combined heat treatment on D value in fruit and vegetable juice was also studied.The main findings are as follows:1 L.plantarum JL-A65 as adjunctive starter apply in cheese.The results of the L.plantarum JL-A65 growth curve showed that from the 12h into stationary period,and the ability to produce acid was weak,so it was suitable as adjunctive starter.The effects of lactic acid bacteria on E.coli?the physicals chemical indexes?texture of the cheese were studied during the fermentation process and 4?storage.The results showed that the number of E.coli in the L.plantarum JL-A65 group was 0.2 logCFU/mL lower than in the blank group.During the storage at 4? the experimental group S1,S2 and S3 lower than the blank group were 2 logCFU/g,4 logCFU/g,7 logCFU/g at the 3th day,and no E.coli was detected on days 9,6 and 3,respectively The results showed that L.plantarum JL-A65 could effectively inhibit the growth of E.coli in cheese,and the effect of adding L.plantarum JL-A65 was more obvious.The protein,fat content and texture difference of each groups were not significant,indicating that the addition of L.plantarum JL-A65 did not have a negative impact on the quality of the cheese.2.Application of BacteriocinJL-A65 in Preservation of Fruit and Vegetable.Juice.The minimum inhibitory concentrations of bacteriocinJL-A65 to carrot juice and E.coli in pear juice were 384 ?g/mL and 256 ?g/mL,respectively.E.coli was initially inhibited at the initial concentration of 106 CFU/mL at 4 h after addition of bacteriocinJL-A65 in fruit and vegetable juice.The antibacterial effect of bacteriocinJL-A65 in low pH fruit and vegetable juice is better,,At same concentration of bacteriocinJL-A65,pH 4.5 in carrot juice,the number of E.coli less than pH 6.5 about 2 logCFU/mL;At same concentration of bacteriocinJL-A65,the carrot juice in the inhibition of E.coli is better,pH 4.5 carrot juice,pear juice minimum inhibitory concentrations were 128.256 ?g/mL,pH 5.5 carrot juice,pear juice minimum The inhibitory concentrations were 256?384 pg/mL,The bacteriostatic effect of bacteriocinJL-A65 on E.coli in carrot juice was determined.Under the condition of storage at 4?,when the amount of bacteriocinJL-A65 was 256?384 ?pg/mL,E.coli was completely inhibited on day 2 and day 1.Carrot juice at a temperature of 30 ? storage conditions,128 pg/mL of the bacteriocinJL-A65 concentration on the first day less than the control group about 1.5 logCFU/mL,bacteriocinJL-A65 concentration of 256 ?g/mL on the first day less than the control group about 3 logCFU/mL,and 384?g/mL was added to inhibit the growth of the large intestine on the first day.E.coli was not detected on day 1 at 384 ?g/mL.3.In Fruit and VegeTab.Juices the effects of Heat Treatment Combined with bacteriocinJL-A65 on D Value.It was determined that bacteriocinJL-A65 combined with heat treatment could effectively reduce the D value in fruit and vegetable juice.The D values of heat treatment(45?,55?,60?)in carrot juice were 28.49?7.67?2.28 min,D value decreased by 9.89?4.78?2.32 min after adding bacteriocinJL-A65,heat treatment in pear juice(45?,55?,60?)were:27.55?5.46?1.91 min,and the D value decreased by 2.19?1.13?0.65 min after adding bacteriocinJL-A65.