Effect of the thermoultrasonic treatment on the eggshell integrity and their impact on the microbial quality

A study of the effect of thermoultrasonication on the ultrastructure and physical properties of the eggshell has been conducted as well as an evaluation of possible bacteria penetration including salmonellae, to the inside of egg. No effect of treatment was found in the physical properties of shell stored in different conditions nor was the structure of the eggshell affected, except for the cuticle. Most of the outer surface, including pores, of the thermoultrasonicated eggshell lacked the cuticle outer layer but cuticle residues remained within the mouth of the pore. This fact, probably led to maintaining the occlusion of the eggshell pores since both yolk and white remained sterile after three weeks of storage under several temperature and relative humidity conditions. Contaminated eggshells are among the leading sources of human infection with Salmonella enterica, serovars Enteritidis and Typhimurium ( S. Enteritidis and S. Typhimurium). We have successfully developed a system using heat and ultrasound, simultaneously applied (thermoultrasonication) to eliminate these organisms on the surface of intact eggs. Although, it would be necessary to develop equipment for larger scale application, this treatment provides many advantages from an industrial point of view because it is possible to pasteurize the surface of intact eggs by applying a thermoultrasonic treatment. This process yields a product that has a safe level of salmonellae with negligible damage to the thermolabile egg components. ► No thermoultrasonic effect in the physical properties of eggshell was found. ► No thermoultrasonic effect on structure of eggshell calcified zone was produced. ► The thermoultrasonicated shell eggs maintained the cuticle covering the shell pores. ► No thermoultrasonic effect on bacterial penetration through eggshell was observed.