Computational fluid dynamics simulation studies on pasteurization of egg in stationary and rotation modes

Eggs contain many nutritive compounds and are consumed all over the world. Pasteurization is an important unit operation for inactivation of pathogenic bacteria and is widely used for inactivation of Salmonella enteritidis. Experimental studies and computational fluid dynamics (CFD) simulations were performed on thermal pasteurization of egg at 55.6 °C. In this study, CFD simulation of temperature predictions was validated with experimental measurements of the temperature in the egg without yolk. After validation, a whole egg (with yolk) was simulated in CFD at two different modes namely stationary and rotation (at 2.5 and 5 rpm). These results revealed that the stationary egg took about 30 min to reach the pasteurization temperature, whereas, rotating egg needed only 9.5 min. This reduction in processing time minimizes the thermal damage of the egg's nutrients. Hence, rotation of egg made the thermal pasteurization process more efficient. Moreover, prediction of inactivation of S. enteritidis based on the process value F (min) also reinforced the positive effect of rotation during thermal pasteurization.Industrial RelevanceIn recent years, a rapid development in the application of CFD in food processing operations has been witnessed. The main need for CFD analysis of pasteurization is to determine the uniform and effective heat distribution in the egg and to examine the position of slowest heating zone (SHZ). Relatively few works have been published related to applications of CFD in thermal processing of egg. However, all the studies were performed for a stationary position of egg during thermal process. So far, no works have been published on the pasteurization of egg in a rotation mode. Hence, the present study was aimed at investigating the effects of pasteurization of egg at 55.6 °C on pasteurization time. Rotation mode of pasteurization decreases the time of pasteurization by a large extent and makes more energy efficient process. Hence, it is advantageous for food industries to adopt rotation as an additional operation during pasteurization of eggs to produce high quality intact eggs without affecting its functional properties.

Research Highlights
► CFD model for thermal pasteurization of static egg was developed and validated with the experimental measurements.
► Thermal pasteurization of a stationary egg is a time consuming process compared to rotated egg.
► Locally calculated F-value (based on temperature predictions) indicated that the time required for inactivating the Salmonella was drastically reduced by rotation of egg compared to static position.