Effects of External Factors and Eucommia ulmoides Leaves Extracts on Antibacterial Activity of SDA

The effects of food ingredients(concentrations of protein and carbohydrate)and processing conditions(temperature and pH)on the antibacterial activity of SDA,and the combined antibacterial effect of SDA and EULE were investigated. The Modified Gompertz kinetic analyses was used to fit the bacterial growth curve. And the lag phase(λ)and maximum specific growth rate(μ_max)of Salmonella and Staphylococcus aureus were obtained. The MIC of SDA and EULE were determined by double dilution method. The antibacterial effect of SDA combined with EULE was investigated by checkerboard method. The results showed that high concentration of protein(10% beef extract desiccant),high concentration of carbohydrate(7% soluble starch),high temperature treatment(121 and 138 ℃)and alkaline condition(pH8.5)all decreased the antibacterial efficiency of SDA. However,SDA was more effective at acidic conditions(pH4.5,5.5 and 6.5). And when SDA was combined with EULE,there was an additive effect on the antibacterial activity. It could provide a theoretical reference for the application of SDA in food industries.