Effects Of The Raw Meat And The Auxiliary Ingredient On Bacterial Flora Structure,Nitrogen Compounds And Biogenic Amines In Fermented Beef Sausages

To investigate the effect of the quality of raw meat and the amount of auxiliary additives on bacteria flora structure,nitrogen compounds and biological amines in fermented beef sausage.Traditional microbial culture method,high throughput sequencing method,high performance liquid chromatography,kjeldahl nitrogen method and so on were used to determine the content of microorganisms,bioamines,total nitrogen,volatile base nitrogen and amino acid nitrogen in sausage.The main results and conclusions were as follows:1.Effects of the quality of raw meat on changes of bacterial flora structure,nitrogen compounds and biogenic amines in fermented beef sausages（1）By studying the influence of the contamination degree of raw meat on the structure of bacteria flora,nitrogen compounds and the content of biological amines in fermented beef sausages,results showed that,with the increase of the contamination degree of the raw beef,the total number of bacterial colony,lactic acid bacteria,coliform group,the mold and yeast,the diversity and richness of flora,the total volatile basic nitrogen,tyramine,histamine,cadaverine,putrescine,total content of biogenic amines in fermented sausage were increased,while total nitrogen content,amino acid nitrogen content and free amino acid content were decreased.By comparing sausages made from highly contaminated beef with which made from mildly contaminated beef,the total number of bacterial colonies increased from 1.99×10⁷CFU/g to 8.06×10⁷CFU/g（P<0.05）,the Shannon index increased from 1.39 to 3.27,the dominant bacteria group changed from Staphylococcus as the main flora during the whole processing stages to Lactobacillus as the main flora in the early stage and Enterococcus,Pseudomonas in the late stage.The total free amino acid content reduced from 7.27 mg/g to 6.75 mg/g,the total biogenic amine content increased from 89.54 mg/kg to 159.83 mg/kg（P<0.05）.（2）By studying the influence of the refrigerating time of raw meat（0～4℃）on the structure of bacteria flora,nitrogen compounds and the content of biological amines in fermented beef sausages,the result showed that,with the increase of cold storage time of raw beef,the total number of bacterial colony,the number of lactic acid bacteria and coliform group bacteria,the mold and yeast,the diversity and richness of flora,the total volatile basic nitrogen,the amino acid nitrogen content,tyramine,histamine,cadaverine,putrescine,total content of biogenic amines in fermented sausage were increased,while the content of total nitrogen content and free amino acid were decreased.Through comparing sausages made from beef refrigerated for 36 h with which made from fresh beef,the total number of bacterial colonies increased from 1.99×10⁷CFU/g to 4.03×10⁷CFU/g（P<0.05）,the Shannon index increased from 1.39 to 2.83,the dominant bacteria group changed from Staphylococcus as the main flora during the whole processing stages to Weissella as the main flora in the early stage and Staphylococcus in the late stage.The total free amino acid content reduced from 7.27 mg/g to 6.81 mg/g,the total biogenic amine content increased from 89.54 mg/kg to 117.41 mg/kg（P<0.05）.（3）By studying the influence of the freezing time of raw meat（-18℃）on the structure of bacteria flora,nitrogen compounds and the content of biological amines in fermented beef sausages,the result showed that,with the increase of freezing storage time of raw beef,the total number of bacterial colony,the number of lactic acid bacteria,coliform group bacteria and the mold and yeast,the total nitrogen content,the volatile basic nitrogen content in fermented sausage were decreased,while the amount of amino acid nitrogen content,tyramine,histamine,cadaverine,putrescine,total biogenic amines were increased.By comparing sausages made from beef frozen for 90 d with sausages made from fresh beef,the total number of bacterial colonies decreased from 1.99×10⁷CFU/g to 9.80×10⁶CFU/g（P<0.05）,The volatile basic nitrogen content reduced from11.06 mg/100g to 9.35mg/100g,the total biogenic amine content increased from 89.54 mg/kg to 109.27 mg/kg（P<0.05）.2.Effects of the add amount of auxiliary ingredients on changes of bacterial flora structure,nitrogen compounds and biogenic amines in fermented beef sausages（1）By studying the influence of the add amount of Na Cl on the structure of bacteria,nitrogen compounds and the content of biological amines in fermented beef sausages,results showed that,while ensuring the quality and flavor of fermented sausages,with the increase of the add amount of Na Cl,the number of bacterial colony,lactic acid bacteria,coliform group bacteria,mold and yeast,and the content of volatile basic nitrogen,amino acid nitrogen,and the content of tyramine,histamine,cadaverine,putrescine,total biogenic amines in fermented sausage were decreased.（2）By studying the influence of the add amount of Na NO₂on the structure of bacteria,nitrogen compounds and the content of biological amines in fermented beef sausages,the result showed that,within the range of Na NO₂additions allowed by national standards,with the increase of add amount of Na NO₂,the total number of bacterial colony,the number of lactic acid bacteria,coliform group bacteria,the mold and yeast,the content of volatile basic nitrogen in fermented sausage were decreased,while the content of the total nitrogen and histamine were increased.（3）By studying the influence of the add amount of white granulated sugar on the structure of bacteria,nitrogen compounds and the content of biological amines in fermented beef sausages,the result showed that,within the range of addition quantity in this experiment,with the increase of the add amount of white granulated sugar,the total number of bacterial colony,lactic acid bacteria,coliform group bacteria and the mold and yeast in the later stage of sausage processing were decreased,while the content of the volatile basic nitrogen in the whole process of sausage was increased.3.Effects of the quality of raw meat and the add amount of auxiliary ingredient on the correlation between the amount of microorganisms,nitrogen compounds and biological amines in fermented beef sausages（1）The contamination degree of raw meat had a significant impact on the correlation between the number of coliforms,the content of volatile,basic nitrogen cadaverine and total biogenic amine in the mature stage of sausage,all of the above showed obviously positive correlation（P<0.01）;The refrigerating time of raw meat had a significant influence on the correlation between the number of lactic acid bacteria,the content of volatile basic nitrogen and the content of total biogenic amine in the maturation stage of sausage,all of the above showed extremely positive correlation（P<0.01）;The freezing time of raw meat had a significant negative impact on the correlation between the total number of bacterial colony and tyramine content in the mature stage of sausage（P<0.01）.（2）The add amount of Na Cl had a significant positive correlation with the total number of bacterial colonies,the content of volatile basic nitrogen and the content of total biogenic amine in the mature stage of sausage（P<0.01）;The add amount of Na NO₂had a significant negative correlation with the number of coliform bacteria and the content of histamine during the maturation stage of sausage（P<0.01）;The add amount of white granulated sugar had a significant positive correlation with the number of coliform bacteria,the content of volatile basic nitrogen and the content of histamine（P<0.01）.