| In this experiment,the total 24 lactic acid bacteria in the laboratory were respectively studied on their antioxidation,and the one with the best antioxidation was selected by testing their ability to scavenge the DPPH,hydroxyl radical and superoxide radical,and to chelate ferrous ions.Afterwards,it was used to make fermented mutton jerky.The experiment contained 4 groups:the control group,the starter group,the spices group and the mix group(containing both the starter and spices)and then profoundly studied the influence of the starter and spices to the physicochemical indexes,microbial indexes and volatile flavour compounds of fermented mutton jerky.The experimental results are as follows:1.According to the primary selection results of lactic acid bacteria,HB5,37X-9,37X-10 and 37X-15 were tested to have good antioxidation.After the antioxidant capacity of strains were further tested,the pediococcus pentosaceus 37X-15 was finally assured to have the best antioxidation,whose rates of scavenging DPPH free radical and superoxide radical were respectively up to 58.55%and 46.96%,ability to eliminate hydroxyl radical was around equal to the VC control group and rate of chelating ferrous ions was up to 91.49%.Therefore,pediococcus pentosaceus has relatively high antioxidation.2.The pH of the starter group reduced to 5.22 after ferment and the figure of the mix group was 5.20,both remarkably lower than that of the control group(5.64,p<0.05);After the maturity,the water activity of the starter group decreased to 0.733,significantly lower than that of the control group(0.796,p<0.05).In terms of the mix group,the figure of redness was 16.02,quite higher than that of the control group(15.72,p<0.05);the figures of the nitrite content and TBARS were respectively 0.532mg/kg and 0.563,both dramatically lower than those of the control group(2.551mg/kg and 1.069 respectively,p<0.05).3.After the ferment of mutton jerky,in terms of the starter group,the numbers of lactic acid bacteria and staphylococcus were 8.1 X 108CFU/g and 7.4 × 108CFU/g,respectively,drastically higher than the figure of the control group(5.1× 107 CFU/g and 3.6×106CFU/g respectively,p<0.05);The number of coliform bacteria was 6.6×102CFU/g,singularly lower than that of the control group(1.01×103CFU/g,p<0.05).Besides,after maturity and air drying,in all groups,there were no coliform bacteria detected.4.In the maturity state of traditional technology,in terms of the starter group,the hexanal content was 1.56(? g/500g),significantly lower than that of the control group[5.53(?g/500g),p<0.05]and not detected in the spices group and the mix group;After the imitation of air drying in factories,the heptaldehyde content was 1.62(?g/500g),remarkably lower than that of the control group[3.65(?g/500g),p<0.05]and not detected in other groups.Flavour compounds of aldehyde of straight chains were from the oxidative decomposition of the fat.The more their content were,the higher the degree of the oxidative decomposition of the fat was,which indicates that the starters and spices can effectively lessen the degree of the oxidation of the fat.5.In the maturity state of traditional technology,propionic acid,isobutyric acid and oleic acid were detected and the mutton jerky tasted sour,while after the imitation of air drying in factories,substances mentioned above were not detected,which means the mutton jerky processed by traditional ferment technology is more equipped with unique flavour,the characteristic sourness of fermented jerky. |
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