Study On Lactic Acid Bacteria From Marine Fish As Biopreservative In Seafood

Aquatic products provide abundant nutrients for human beings and are very popular among consumers.However,aquatic products tends to spoil.The spoilage bacteria are one of the main causes of spoilage,so a reasonable preservation methods are necessary.Bio-preservation is a fresh-keeping method that utilizes natural flora and its antibacterial products to extend the shelf life of foods and improve food safety.Lactic acid bacteria have potential to be a biopreservative.In this paper,LABs strains isolated from marine fish were screened for biopreservative,then applied to fish juice and fresh crap flesh to verify the potential of lactic acid bacteria as biological preservation.Firstly,screen suitable lactic acid bacteria biopreservative.The lactic acid bacteria with biopreservation potential were screened from 14 strains of lactic acid bacteria preserved in the laboratory through bacteriostatic test,spoilage potential,environmental tolerance(low temperature and salinity)and safety evaluation experiments.L.casei Y3 had weak antibacterial activity and was not suitable for inhibit spoilage bacteria.L.plantarum Y37,L.plantarum S2-6 and Enterococcus.2 produced poor flavor,not accepted by sensory acessors.When the salt concentration reached 6%,survival rate of LAB strains dropped sharply but most of them had high tolerance to high salt concentration.L.plantarum Y12,L.plantarum Y3-1 and Enterococcus B2-10 had poor survival rate under low temperature conditions,which is not suitable for bio-preservation.The LAB strains did not produce histamine and tryptamine in fish juice.L.plantarum Y41,L.plantarum Y44 and L.sakei B2-4 were not resistant to most antibiotics.After the above screening requirements,three LABs strains are suitable as biopreservative,such as:L.plantarum Y41,L.plantarum Y44 and L.sakei B2-4,finally L.sakei B2-4 was selected as the subsequent experimental strain among the three strains.Secondly,apply L.sakei B2-4 to sterilized fish juice to inhibitiof Shewanella Shewanella.spp.By electronic nose and sensory analysis,L.sakei B2-4 can effectively enhance the sensory analysis.Through chemical indicators,the ability of L.sakei B2-4 to inhibit spoilage bacteria in fish juice was studied by sensory evaluation and phy-chemical determination.The pH of the mixed culture fish juice is lower than that of S.putrefaciens.The volatile base nitrogen(TVBN)content of the fish juice inoculated with L.sakei B2-4 and S.putrefaciens was lower than the TVBN content of the fish juice inoculated woth S.putrefaciens alone.The concentration of 10~8CFU/mL L.sakei B2-4 had stronger inhibition to S.putrefaciens than 10~6 CFU/mL L.sakei B2-4.However,the concentration of cadaverine was higher along with LAB concentration in fish juice.In general,LAB can inhibit spoilage bacteria and improve the phy-chemical indicators and sensory quality of aquatic products.Finally,verify the biopreservation effect of LAB in fresh carp surimi.The biological preservation effect of L.sakei B2-4 on carp flesh.The results of sensory evaluation showed that the sensory quality of the.The results of sensory evaluation showed that the sensory quality of the surimi inoculated inoculated with L.sakei B2-4 increased.With the prolongation of preservation time,the pH decreased,and the pH of ground carp flesh inoculated with 10~8CFU/mL was lower than that of in ground carp flesh inoculated with 10~6 CFU/mL.The content of TVBN in no treatment ground carp flesh was significantly higher than that of ground carp flesh inoculated with L.sakei B2-4.Thiobarbituric acid(TBA)was significantly lower than when L.sakei B2-4was inoculated in ground carp flesh,inoculating L.sakei B2-4 delayed oxidation of fat.Putrescine and cadaverine decreased when the concentration of L.sakei B2-4increased.According to the results of bacterial abundance,L.sakei B2-4 can reduce the abundance of bacteria in ground carp flesh and inhibit spoilage bacteria.This study found that L.sakei B2-4 has ability to prolong shelf life of aquatic products through preservation experiments,and has the potential to act as fish biological preservative.