Bactericidal treatment of hatching eggs II. Use of chemical disinfectants with vacuum to reduce salmonella

In an attempt to draw chemicals deeper into the egg to kill bacteria, vacuum was used. Hatching eggs (42 degrees C) were inoculated by 1 min dip in a suspension of 10(4) cells/mL Salmonella typhimurium or Salmonella heidelberg maintained at 21 degrees C. Following a 4-hr drying period, the eggs were immersed into 0.035% polyhexamethylenebiguanide hydrochloride (PHMB) or 1.4 hydrogen peroxide (H2O2). Atmospheric pressure dip (10) was compared to a vacuum cycle (4 min) followed by an atmospheric pressure dip (6 min). Immersion in PHMB without the vacuum step resulted in elimination of S. typhimurium from 26 of 30 eggs and S. heidelberg from 23 of 30 eggs. Use of H2O2 as an atmospheric pressure dip resulted in the elimination of S. typhimurium from 17 of 30 eggs and S. heidelberg from 24 of 30 eggs. Addition of the vacuum step increased the effectiveness of both chemicals against both strains of Salmonella. Immersion in PHMB with the vacuum step resulted in eliminating S. typhimurium from 29 of 30 eggs and S. heidelberg from 24 of 30 eggs. Use of H2O2 with the vacuum resulted in the elimination of S. typhimurium from 27 of 30 eggs and S. heidelberg from 27 of 30 eggs. When applied with a vacuum, neither 1.4% H2O2 nor 0.035% PHMB had any adverse effect on hatchability.