A microbial challenge study for validating continuous radio-frequency assisted thermal processing pasteurization of...

Area of Science:

• Food Science
• Food Engineering
• Microbiology

Background:

• Traditional hot room treatment for egg white powder (EWP) pasteurization is time-consuming (15 days at 67°C).
• Radio-frequency (RF) assisted thermal processing offers a potential method to reduce EWP processing times while preserving functionality.
• Continuous RF processing needs evaluation for effective EWP pasteurization.

Purpose of the Study:

• To evaluate continuous RF processing for pasteurizing spray-dried egg white powder (EWP).
• To assess the efficacy of RF heating against microbial contaminants like Salmonella and Enterococcus faecium.
• To determine if E. faecium can serve as a surrogate for Salmonella in RF pasteurization studies.

Main Methods:

• Spray-dried EWP samples were inoculated with a 5-strain Salmonella cocktail or Enterococcus faecium.
• Stability and homogeneity of microbial inocula in EWP were tested.
• Continuous RF heating was performed using a pilot-scale parallel-plate RF system (6 kW, 27.12 MHz).

Main Results:

• RF-assisted thermal processing at 80°C for 2 hours achieved a >6.69 log reduction for Salmonella in EWP.
• Enterococcus faecium exhibited higher resistance and similar inactivation kinetics to Salmonella during RF heating, validating its use as a surrogate.
• The RF processing method effectively reduced microbial load without compromising EWP functionality.

Conclusions:

• Continuous RF processing is an effective method for pasteurizing egg white powder.
• Enterococcus faecium can be used as a suitable surrogate for Salmonella in RF pasteurization studies of EWP.
• The validated RF-assisted thermal process is scalable for industrial application in the egg industry.