This study aimed to compare the three strains of Listeria monocytogenes survival in raw milk cheese and pasteurized milk cheese and to suggest the effect of milk microbiota on survival. L. monocytogenes cell counts decreased in all cheese as ripening time increased, and the survival rate was different for the strains of L. monocytogenes. Furthermore, L. monocytogenes survived longer in raw milk cheese than in pasteurized milk cheese. The difference of bacterial survival in each cheese was independent of Aw or the Lactobacillus spp. populations in cheeses; there was no difference in Aw or Lactobacillus spp. populations in all cheeses. The richness of microbiota in raw milk was little higher than in pasteurized milk, and five phyla (Chloroflexi, Cyanobacteria, Deinococcus–Thermus, Lentisphaerae, and Verrucomicrobia) were present only in raw milk. Also, organic acid‐producing bacteria were presented more in pasteurized milk compared with raw milk; thus, the growth of L. monocytogenes was slower in pasteurized milk. In conclusion, differences in the microbial community of milk can affect the growth of L. monocytogenes. Making cheese using raw milk is a risk of L. monocytogenes infection; thus, efforts to prevent growth of L. monocytogenes such as the use of appropriate food additives are required.

The market size of the home meal replacement (HMR) is continuously increasing. However, there are high concerns about safety such as poor hygiene of companies and detection of foodborne pathogens in HMR. This study analyzed the contamination level of total aerobic bacteria and 5 types of foodborne pathogens in 30 Ready-to-Eat foods (20 Gimbap, 5 sandwiches and 5 hamburgers). As a result, it was confirmed that total aerobic bacteria were contaminated with at least 67 CFU/g and up to 412 CFU/g in 12 samples. Staphylococcus aureus (11-132 CFU/g) and Bacillus cereus (41-233 CFU/g) were contaminated in 9 samples. The microbial contamination level was the highest in Gimbap. Small amounts of foodborne pathogens can multiply during inappropriate distribution and storage, causing foodborne illness. Therefore, to expand and growth of HMR industry further, it is considered necessary to secure microbiological safety through continuous monitoring of HMR and hygiene management of companies.

Bacillus cereus (B. cereus) is a spore forming bacteria with a highly adhesive ability on the food surface and which expresses concern about commercial sterilization due to heat resistance. In this study, the heat challenge was performed at 60℃ for 60 min to derive the importance of the inactivation of bacteria by time during heating 14 isolates of B. cereus from the tomato farm environment. As a result, the final cell counts of B. cereus reduced after heating were -3.6 Log CFU/mL on average (minimum: -2.8 Log CFU/mL, maximum: -4.7 Log CFU/mL). Reduced cell counts of B. cereus after heating for 60 min ranged from 0.5 Log CFU/mL to 2.4 Log CFU/mL. Remained B. cereus after heating can recover in an appropriate environment, and cause foodborne illness. B. cereus existed in the farm environment during the cultivation stage of agricultural products can be transferred to agricultural products through various routes such as soil, toilet handles and worker gloves, thus, the management of B. cereus in a farm environment is essential. In addition, improper sterilization, manufacturing, processing and packaging in the food processing stage cannot be expected to inhibit the complete growth of foodborne pathogenic bacteria, and the risk of foodborne illness can be increased. Therefore, thorough management of these processes is considered important.

No abstract