Method and apparatus for pasteurizing shell eggs using radio frequency heating
Radio frequency (RF) energy is used to quickly heat the yolk portion of a shell egg. An anode and corresponding cathode are applied to each individual egg. As the egg is selectively and systematically rotated, RF energy and a stream of cooling fluid (preferably water) are simultaneously applied to the egg. This initiates pasteurization of the egg yolk while maintaining a low temperature in the heat-sensitive albumen (egg white) thus preventing denaturation of the albumen. Immediately after the RF yolk heating process, the egg is placed in a hot water bath designed to rapidly pasteurize the albumen as well as to minimize heat loss from the yolk and pasteurize any portion of the yolk that is not already pasteurized through the RF yolk heating process.
1. A method of pasteurizing a yolk of a shell egg comprising the steps of:
(a) positioning at least one electrode to contact the egg, the electrode transferring RF energy to the egg;
(b) rotating the egg with a rotating assembly comprising a plurality of rollers causing relative rotation between the at least one electrode and the egg;
(c) directing the RF energy from the electrode to the rotating egg to penetrate the egg and thereby directly heat and pasteurize the yolk; and,
(d) simultaneously cooling the egg albumen by directing a stream of cooling fluid over the rotating egg so that the egg yolk is pasteurized without causing coagulation or denaturation in the albumen.
2. The method of claim 1 wherein, in step (a), the at least one electrode comprises at least first and second electrodes.
3. The method of claim 2 wherein, in step (a), the first electrode is positioned on a midsection of the egg, and the second electrode is positioned opposite the first electrode.
4. The method of claim 1 wherein, in step (b), the rotating assembly is structured so that the rotating assembly rotates the egg at a speed in the range of 5 to 25 revolutions per minute.
5. The method of claim 1 wherein, in step (c), the electrode is structured so that the RF energy applied to the egg is in the range of 5 to 200 watts.
6. The method of claim 1 wherein, in step (c) the electrode is structured so that the RF energy is applied to the egg for a time period in the range of 2 to 10 minutes.
7. The method of claim 1 wherein, in step (c), the RF energy applied to the egg is in the frequency range of 1 to 100 Mhz.
8. The method of claim 1 wherein, in step (b) the egg is positioned on the rotating assembly so that the egg is rotated around a horizontal axis running from the large end of the egg to the small end of the egg.
9. The method of claim 1 wherein the egg yolk is pasteurized to result in at least a five log cycle (99.999%) reduction in bacteria with no damage to the egg albumen.
10. A method of pasteurizing a whole shell egg, the method comprising:
(a) positioning at least one electrode to contact the egg, the electrode transferring RF energy to the egg;
(b) rotating the egg with a rotating assembly comprising a plurality of rollers causing relative rotation between the at least one electrode and the egg;
(c) directing the RF energy from the electrode to the rotating egg to penetrate the egg and thereby directly heat and pasteurize the yolk;
(d) simultaneously cooling the egg albumen by directing a stream of cooling fluid over the rotating egg so that the egg yolk is pasteurized without causing coagulation or denaturation in the albumen; and,
(e) exposing the egg outer shell to heated water or moistened heated air until the whole egg is pasteurized.
11. The method of claim 10 wherein, in step (e), the egg is exposed to the hot water by immersing the egg is a hot water bath.
12. The method of claim 10 wherein in step (e), the egg is exposed to the hot water by a fluid applicator that directs the hot water over the egg.
13. The method of claim 10 wherein the whole egg is pasteurized to result in at least a five log cycle (99.999%) reduction in bacteria with no damage to the egg albumen.