| In this research, strains were isolated and screened from starter cultures of fermented sausages. Their capacity of acid and enzyme production , their Application in fermented sausages and the relation between pH value and strains' growth during the course of the fermention and ripening were analyed. The results were as followed:1.Among the 13 strains, 3.2MRS, 3.3 MRS were classified as Lactobacillus sake; 3.4 MRS as Lcasei; 3MRS as L. curvatus; 4MRS1, 4MRS2,5MRS as L plantarum; 4S as Pedicoccus pentosaceus; 3.2MSA, 3MSA, 4MSA, 5MSA as Staphylococcus camosus; 3.4MSA as S.xylosus. The growth rate of 3.2MRS was thequickest, and 3MRS was the slowest. There were not obvious difference between the two kinds of staphylococci ' growth rate. Temperature influenced highly the growth rate, and the order of growth rates at different temperature were V30>V35>V40>V25>V45 >V20>V15.Most strains' optimal temperature was 30. 2. The five kinds strains of lactic acid bactertia had some difference acidifying capacity. In MRS broth, the slowest rate of declining pH value was 3 MRS,and 3.2 MRS was the fastest. Different broth had significate effect on acidifying capacity. Additing 150ppm nitrate inihibited all of lactic acid bacteria; Additing NaCL inihibited 3MRS, but stimulated 3.2MRS. 3.4MRS, 4MRS, 4S. Staphylococci showed little effect on acidifying capacity.3.The proteolytic activity varied according to temperature. All strains had no activities of proteinase at 15 and at 20 only 3.2MRS had weak proteolytic activity.There were clearly different activities of proteinase at 30. Among them , proteinase activity of 3.2MRS was the highest and 3MRS was the lowest. None of lactic acid bacteria produce lipase, but Staphylococci could produce lipase and showed weak lipolytic activities against pork back fat.4.The AW of fermented sausages was 0.975 at the beginning , and was 0.929 at the end of ripening.S.Compared the contronl (C1 without GDL ) with treatments(additing GDI), the pH value of C1 was above 5.70 during 18 hours, and decreased to 5.3 after 26 hours.The pH value of treatments decreased to 5.5 after 2 hours becaue GDL hydrolysed, which leaded to pH drop.6.Additing different content of glucose caused significant difference in pH value dropping(p<0.05). Ehancing glucose content could increase the rate of declining pH value and preven pH value rising during the ripenging.Using different Staphylococci also leaded to significant difference of pH value (p<0.05). 3.4MSA produced alkaline substances in broth, which made pH value raised, on the contrary, 3.2MSA produced acid, which made pH value decend..7.The population of Lactic acid bacteris in A2, A4, A5, A7 ,A8 always increased during 10 days, but in A1, A3, A6 decreased at the late ripening. A2 had the hightest number, which was 12.033, and A4 had lowest,which was 9.851. the population of Staphylococci differed widely each other in different groups.8. The pH value reached the lowest value after 3 days in all the groups. Subsequently the pH increased. A1 and A7 had the quickest rate of production acid, and the capacities of their production acid also were the biggest. The highest rate of increasing pH value took place in A6 and A8, which had reached to 5.2 by the end of ripening. 9.To describe the evolution of pH values during the ripening process of fermented sausages, the use of a mathematical model was proposed.Y=5.69-0.96e-e-1.79(x-0.9)+0.33e-e-1.11(x-6.86)The mathematical development of the function showed the most rapid decline in pH occurred on the 22th hour of ripening, and the most rapid increase in pH occurred after 6 days and 20 hours of ripeningFour stages could devided into the course of the ripening of fermented sausages: (1)Latency in the release of protons: This period ended in 7 hours after the ripening; (2)Exponential decline in pH: This period ended in one day and 12 hours after the ripening;(S)Stationary stage: This period ended in 3 days after after the ripening; (4)pH value contined to increase until th...
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