title: Eggshell penetration of various types of hens' eggs by Salmonella enterica serovar Enteritidis.
abstract: Egg weight, shell thickness, number of pores, cuticle deposition, eggshell strength (dynamic stiffness and damping ratio), and the ability of Salmonella enterica serovar Enteritidis (SE) to penetrate the eggshell were determined. Penetration was assessed by filling the eggs with a selective medium that allowed viewing of Salmonella growth on the inside of the shell and membrane complex. After inoculation of each shell with on average 2.71 log CFU, the eggs were stored for up to 14 days at 20 degrees C and 60% relative humidity. Commercially available eggs were used. At 14 days of storage, only 6.0% of the eggs from free-range hens and 16.0% of the generic (i.e., eggs from hens in conventional battery cages that were given standard feed) white eggs were penetrated. The generic brown, organic, and omega-3-enriched eggs were penetrated at a frequency of 30 to 34%. In a second experiment it was shown that the layer strains of the hen (ISA-Brown Warren versus Bovans Goldline), which were kept in furnished cages, did not affect eggshell penetration by SE. For Bovans Goldline hens, the housing system (furnished cage versus aviary) did not affect penetration, while a trend was visible toward a higher fraction of penetrated eggshells when hens were fed corncob mix rather than standard feed. Eggshell penetration was observed more frequently in the absence of cuticle spots and for eggs having lower dynamic stiffness values. Shell contamination at the end of storage was highly correlated with SE penetration.
authors: Institute for Agricultural and Fisheries Research (ILVO), Technology and Food Unit, Brusselsesteenweg 370, B-9090 Melle, Belgium. winy.messens@ilvo.vlaanderen.be
authors: Winy
authors: W
authors: Messens
authors: Koen
authors: K
authors: Grijspeerdt
authors: Koen
authors: K
authors: De Reu
authors: Bart
authors: B
authors: De Ketelaere
authors: Kristof
authors: K
authors: Mertens
authors: Flip
authors: F
authors: Bamelis
authors: Bart
authors: B
authors: Kemps
authors: Josse
authors: J
authors: De Baerdemaeker
authors: Eddy
authors: E
authors: Decuypere
authors: Lieve
authors: L
authors: Herman
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002645:Chickens; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004528:Egg Shell / Q000033:anatomy & histology / Q000382:microbiology* / Q000502:physiology; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D006801:Humans; D006813:Humidity; D012477:Salmonella enteritidis / Q000254:growth & development / Q000502:physiology*; D013696:Temperature; D013997:Time Factors