title: Effect of milk fat content on the performance of ohmic heating for inactivation of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium and Listeria monocytogenes.
abstract: OBJECTIVE
  The effect of milk fat content on ohmic heating compared to conventional heating for inactivation of food-borne pathogens was investigated.
  
  
  RESULTS
  Sterile cream was mixed with sterile buffered peptone water and adjusted to 0, 3, 7, 10% (w/v) milk fat content. These samples with varying fat content were subjected to ohmic and conventional heating. The effect of milk fat on temperature increase and electrical conductivity were investigated. Also, the protective effect of milk fat on the inactivation of foodborne pathogens was studied. For conventional heating, temperatures of samples increased with time and were not significantly (P > 0.05) different regardless of fat content. Although the inactivation rate of Escherichia coli O157:H7, Salmonella Typhimurium and L. monocytogens decreased in samples of 10% fat content, a protective effect was not observed for conventional heating. In contrast with conventional heating, ohmic heating was significantly affected by milk fat content. Temperature increased more rapidly with lower fat content for ohmic heating due to higher electrical conductivity. Nonuniform heat generation of nonhomogeneous fat-containing samples was verified using a thermal infrared camera. Also, the protective effect of milk fat on E. coli O157:H7 and Listeria monocytogenes was observed in samples subjected to ohmic heating.
  
  
  CONCLUSIONS
  These results indicate that food-borne pathogens can survive in nonhomogeneous fat-containing foods subjected to ohmic heating. Therefore, more attention is needed regarding ohmic heating than conventional heating for pasteurizing fat-containing foods.
  
  
  CONCLUSIONS
  The importance of adequate pasteurization for high milk fat containing foods was identified.
authors.affiliation: Department of Food and Animal Biotechnology, Center for Food and Bioconvergence, and Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul, Korea.|Institutes of Green Bio Science & Technology, Seoul National University, Pyeongchang-gun, Korea.
authors.forename: S-S
authors.initials: SS
authors.lastname: Kim
authors.affiliation: Department of Food and Animal Biotechnology, Center for Food and Bioconvergence, and Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul, Korea.|Institutes of Green Bio Science & Technology, Seoul National University, Pyeongchang-gun, Korea.
authors.forename: D-H
authors.initials: DH
authors.lastname: Kang
mesh_terms: D000818:Animals; D002417:Cattle; D019453:Escherichia coli O157 / Q000254:growth & development*; D005223:Fats / Q000737:chemistry*; D005516:Food Microbiology; D006358:Hot Temperature; D008089:Listeria monocytogenes / Q000254:growth & development*; D008892:Milk / Q000737:chemistry* / Q000382:microbiology; D061352:Pasteurization / Q000379:methods*; D012486:Salmonella typhimurium / Q000254:growth & development*; D013696:Temperature
chemical_list: D005223:Fats
keywords: conventional heating; electrical conductivity; milk fat; ohmic heating; pathogen inactivation; protective effect