Optimization of the radio frequency power, time and cooling water temperature for pasteurization of Salmonella typhimurium in shell eggs

Authors: YANG, YISHAN - Oak Ridge Institute For Science And Education (ORISE); Geveke, David; BRUNKHORST, CHRISTOPHER - Princeton University; Sites, Joseph; GEVEKE, NOAH - Former ARS Employee; Tilman, Eric

Submitted to: Journal of Food Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2018
Publication Date: 1/5/2019
Citation: Yang, Y., Geveke, D.J., Brunkhorst, C.D., Sites, J.E., Geveke, N., Tilman, E.D. 2019. Optimization of the radio frequency power, time and cooling water temperature for pasteurization of Salmonella typhimurium in shell eggs. Journal of Food Engineering. 247:130-135.

Interpretive Summary: Radio frequency (RF) technology rapidly pasteurizes shell eggs without affecting the appearance of the heat-sensitive egg white. However, the effect of varying RF operating conditions (namely, power, treatment time and cooling water temperature) on inactivation of Salmonella and on egg quality was not known. Therefore, shell eggs were processed using RF at powers of 30-45 W, times of 2.5-8 min and cooling water temperatures of 30-38 °C, followed by hot water (HW) treatment at 56.7 °C for 15 min. Five conditions achieved more than a 99.999% kill of Salmonella (pasteurization) without any observable quality change. The results showed, for the first time, that power, time and temperature are interrelated and that the RF process is versatile. Quality analyses indicated that the combined RF/HW treatments preserved egg quality better than HW pasteurization alone (56.7 °C for 60 min), which is the industry standard. This study will help the food industry determine the RF operating conditions for the pasteurization of shell eggs.

Technical Abstract: Radio frequency (RF) power, treatment time and cooling water temperature affect inactivation of Salmonella Typhimurium in shell eggs and internal quality. Eggs were processed using 40.68 MHz RF at 30-45 W, 2.5-8 min and 30-38 C, followed by hot water (HW) treatment at 56.7 C for 15 min. Five conditions achieved >5 log reduction of Salmonella without observable quality change. Analyses of the longest (8 min at 30 W and 30 C) and shortest (4.5 min at 35 W and 38 C) treatments indicated that combined RF/HW treatments significantly (P<0.05) preserved quality better than HW pasteurization (56.7 C for 60 min). No significant (P>0.05) difference in egg quality was observed between the longest and shortest treatment, except that the shortest resulted in greater albumen turbidity. As the longest treatment required 78% more time and 47% more energy than the shortest, industry may wish to use the shortest RF treatment time.