Title Page
Contents
ABSTRACT 13
Ⅰ. INTRODUCTION 16
Ⅱ. LITERATURE REVIEW 19
1. Korean beef 19
1.1. Distribution of Korean beef 19
1.2. Prevalence of foodborne pathogen 22
2. Meat quality 22
2.1. Meat quality indicators 22
2.2. Standards for meat quality 24
3. Meat quality and microorganisms 24
3.1. Meat spoilage bacteria 24
3.2. VBN and microorganisms 25
Ⅲ. MATERIALS AND METHODS 27
1. Prevalence of Korean beef 27
1.1. Collection of samples 27
1.2. Qualitative analysis 27
1.3. Strain isolation and identification 29
1.4. Quantitative analysis 31
1.5. Volatile basic nitrogen (VBN) 34
2. Analysis of microbial composition of Korean beef 35
3. Identification of microorganism related to production of VBN 36
3.1. Bacterial strains 36
3.2. Sample preparation and inoculation of Korean beef 37
3.3. Bacterial enumeration 38
4. Statistical analysis 40
Ⅳ. RESULTS AND DISCUSSION 41
1. Prevalence of Korean beef 41
1.1. Food spoilage microorganisms 41
1.2. Microorganisms related to meat quality 44
1.3. VBN 47
2. Strain isolation and identification 50
2.1. Isolation and identification of microorganisms from Korean beef 50
3. Analysis of Korean beef microbial composition 52
4. Identification of microorganisms related to production of VBN 67
4.1. Bacterial enumeration 67
4.2. pH 69
4.3. VBN 71
4.4. Correlation of microorganism and VBN 73
Ⅴ. SUMMARY AND CONCLUSION 78
Ⅵ. REFERENCE 82
ABSTRACT IN KOREAN 93
Table 1. Qualitative analysis of Escherichia coli and enterohemorrhagic Escherichia coli of Korean beef 42
Table 2. Prevalence of food spoilage microorganisms in Korean beef by the part 43
Table 3. Prevalence of food spoilage microorganisms in Korean beef of distribution stages 46
Table 4. Prevalence of food spoilage microorganisms in Korean beef by grade 48
Table 5. Isolated microorganisms from Korean beef 51
Table 6. Sample information for microbial composition analysis 53
Table 7. pH changes of Korean beef stored at 10℃ for 7 days 70
Table 8. Volatile basic nitrogen changes of Korean beef stored at 10℃ for 7 days 72
Table 9. The spearman's correlation coefficient between the counts of microorganisms and the Volatile basic nitrogen value 74
Figure 1. Distribution of Korean beef and distribution rate in 2021. 21
Figure 2. Volatile basic nitrogen value of the Korean beef by various variables. 49
Figure 3. α-diversity among groups following VBN values. 55
Figure 4. PcoA analysis of Korean beef micobiota among groups following VBN values. 56
Figure 5. Depiction of the representative microbial phylum among groups following VBN values. 57
Figure 6. Depiction of the representative microbial genus among groups following VBN values. 59
Figure 7. Depiction of the representative microbial genus related to meat spoilage among groups following VBN values. 60
Figure 8. Depiction of the representative microbial species among groups following VBN values. 63
Figure 9. Microbial composition of sample No. 70 in phylum, genus and species level. 65
Figure 10. Changes in the number of inoculated microorganisms in Korean beef stored at 10℃ for 7 days. 68