Fermentation Characters And Rheological Properties Of EPS-Producing Lactic Acid Bacteria

4 strains of lactic acid bacteria(LAB)isolated choose from traditional fermentation cream products with potential aggregation characters were study projects.The yield of EPS was screened by the method of Phenol-H2SO4.The fermentation characters and rheological properties of test strains with high EPS-producing ability were tested.Meanwhile the fermentation characters and rheological properties of different ratio of test strains with Streptococcus Thermophiles and Lactobacillus Bulgaricus were tested.The results are as follows:1.High EPS-producing Lactic acid bacteria(LAB)strains isolated from traditional fermentation cream products were LX4 and ZT3-1.Their EPS yield were 336.17±24.90 mg/mL and 313.25±15.36 mg/mL respectively.These 2 strains were identified as Lactobacillus Plantarum through analyzing their colony characteristics,cell morphology,biochemistry and physiological characteristics,and the phylogenetic tree was generated by MEGA 5 software based on 16S rDNA sequence.2.By studying the fermentation characters of LX4 and ZT3-1 and the rheological properties,they both had weak acid-producing ability.The acidity of the yoghourt fermented by ZT3-1 and LX4 after 16h were 74.01±0.68°T and 73.06±0.66°T respectively.Besides,both of the 2 strains could make the yoghourt they fermented have lower whey precipitation,about 30%.3.The control group was fermented by Streptococcus Thermophiles and Lactobacillus Bulgaricus with the ratio of 1:1.While the experimental groups were fermented by the compound of different ratio of lactic acid bacteria strains with Streptococcus Thermophiles and Lactobacillus Bulgaricus.By comparing their fermentation properties,the more amount of strains ZT3-1 and LX4 were used to ferment,the weaker acid-producing ability of mix starter.And when the mixing ratio of the strains was 0.3:1,the yoghourt had lower whey precipitation.4.The yoghourt in the control and experimental groups were all plus thixotropy.When the mixing ratio of the compound between strains ZT3-1,LX4 and the basic strains were all 0.3:1,the yoghourt they fermented had better texture.Apparent viscosity were 120mPa.s and 160mPa.s respectively.Meanwhile the yoghourt they fermented both had a great thermostability.In summary,these 2 high EPS-producing Lactobacillus plantarum had better fermentation characters and helped decrease the rate of whey precipitation and improve rheological properties of fermented milk,so they deserve to put into scale production and generalization.