99E-19

A. REHKOPF, Munich Technical Univ., NCFST/IIT, 6502 S. Archer Road, Summit-Agro, IL 60501 and T. N. Koutchma, National Center for Food Safety and Technology, Illinois Institute of Technology, IIT Moffett Campus, 6502 S. Archer Rd., Summit-Argo, IL 60501.

Pasteurization of shell-eggs is a matter of microbial safety. Microwaves can rapidly provide the thermal energy required to eliminate Salmonella Enteritidis (SE) and drastically reduce the come-up time in existing pasteurization processes. Besides ensuring the absence of pathogenic microorganisms quality deterioration is another critical advantage of microwave pasteurization. Functional properties of eggs have to be determined in the post-pasteurization to validate the process. Our objective is to evaluate and compare retention of quality attributes and functional properties of unpasteurized shell eggs, shell eggs pasteurized via microwaves, and shell eggs pasteurized via conduction heating. The physical properties of eggs such as albumen clarity, emulsion function of the yolk, foam forming ability and stability of beaten egg-white, albumen quality and yolk quality (Haugh-Units), pH, viscosity of the egg-white and egg-weight were measured and compared after conventional heating up to 60^O C in a water bath and microwave applicator. The coupling of applied microwave power was measured and tuned using Network Analyzer. In addition, the surface temperature and temperature in the center of the egg was measured and controlled using infrared camera and fiber optic probes. The microwave cylindrical applicator with the output power of 100 W at 915 MHz was used to heat rotating in-shell eggs. The coupling of microwave energy was optimized allowing to reduce heating time by 8 to 12 seconds to reach the temperature of 55 to 58^O C and increase thermal efficiency of the process. The formation of “peas” in egg yolks was found to be due to overheating. According to turbidity measurements protein denaturation in microwave-processed eggs was less than in conventionally treated eggs. Salmonella-contaminated shell-eggs may pose a serious health hazard for people with a weak immune system like infants, immune-suppressed individuals and elderly people. With pasteurization the hazard of the Salmonellosis will be minimized.

Session 99E, Nonthermal Processing: General II
8:30 AM - 12:00 PM, Wednesday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana