Food or edible material: processes – compositions – and products – Treating unshelled egg
Reexamination Certificate
2002-02-28
2004-02-17
Weier, Anthony J. (Department: 1761)
Food or edible material: processes, compositions, and products
Treating unshelled egg
C426S300000, C426S521000, C426S614000
Reexamination Certificate
active
06692784
ABSTRACT:
BACKGROUND OF THE INVENTION
Pasteurized eggs are relatively new items of commerce in the United States, and indeed, throughout the world. While the art has sought for sometime to devise effective methods for pasteurizing eggs, as described in detail in U.S. Pat. No. 5,843,505, which patent is incorporated herein by reference and relied upon for disclosure, until the existence of the process described and claimed in that patent, pasteurizing of eggs had not been successful either from a commercial point of view or a functionality point of view. Functionality refers to a group of properties of eggs including yoke index, Haugh units, yoke strength, angel cake volume, sponge cake volume, foam stability, whippability, and lysozyme properties. All of these functionalities are well known to the art and are described in detail in the above-noted patent and, for conciseness herein will not be described in detail. However, for example, the angel cake volume is sensitive to egg white protein damage. Heat damage to the protein will increase whipping time and decrease cake volume. Foam stability is a measure of the volume of foam of whipped egg whites. Heat damaged white protein will provide less foam volume and therefore is less desirable in making meringues and the like. Haugh units also measure the foam stability of whipped egg whites and is important in many uses of eggs for baking and cooking. Yoke index is a measure of the yoke height versus the yoke width. When breaking a fresh egg into a pan for frying, if the yoke index is not proper, the yoke will look flat and unappealing in a sunny side up fried egg. Yoke strength is a measure of the strength of the yoke membrane to retain the yoke and is important when frying eggs.
The above-noted U.S. Patent describes and claims processes where eggs may be pasteurized in keeping with the relatively new U.S. Food and Drug Administration definition of pasteurized eggs, which includes a requirement that any Salmonella species in the egg is reduced by an amount equal to at least 5 logs. Those processes are also carried out such that the pasteurized eggs do not have substantial loss of functionality, particularly in regard to the Haugh units, as well as the yoke index and yoke strength.
As a result of the processes described and claimed in that patent, substantial commercialization of pasteurized eggs has now taken place.
Very basically, the processes entail heating raw eggs in a heat transfer medium at certain temperatures within certain parameter lines of a graft shown in that patent and for a time sufficient that a Salmonella species which may be present in the eggs is reduced by an amount of at least 5 logs. In one example of that patent, the internal temperature of the yoke is brought to 133° F. and maintained at that temperature by addition of heated or cooled water to a pasteurizer until any Salmonella bacteria in the egg is reduced by at least 5 logs. Depending upon the particular pasteurizer, the history of the raw eggs being pasteurized, the temperature of the raw eggs entering the pasteurizer and their size, ambient temperatures around the pasteurizer, as well as other factors, a total pasteurizing time of somewhere about 64 minutes or more is required. Of course, the time of dwell of the central portion of the yoke of the eggs being pasteurized will be considerably less than that in accordance with the parameter lines A and B of the graft in that patent. However, the 64 minutes so called total processing time, including the time required to bring the yokes to the temperatures required by that patent for pasteurization, substantially increases the cost of production of pasteurized eggs. It would, of course, be of a substantial advantage to the art to considerably shorten the total processing time required for such pasteurization.
Also, it was found that eggs, which are commercially pasteurized according to that patent, do not have the extended shelf life of the eggs pasteurized in the examples of that patent. Indeed, in commercial pasteurization of the eggs, it was found that a substantial percentage of the pasteurized eggs, even with proper traditional storage conditions, unexpectedly had a shelf life of only about 21 days before rot began to appear in the pasteurized eggs. This, of course, was of concern in regard to the commercial operation, and it was well recognized that this is a disadvantage in the commercial process of pasteurizing eggs and that it would be of substantial advantage to the art to considerably extend the shelf life of the commercially pasteurized eggs.
The above-noted patent also discloses that the heat transfer medium for pasteurizing the eggs may be heated to more than one temperature during the pasteurizing process. However, as a practical matter, having the heat transfer medium, e.g. water, at different temperatures, provides advantages and more efficiency, but requires a series of separate pasteurizing tanks, along with the added capital costs. This also requires placing large volumes of eggs in one tank, removing the eggs from that tank, and placing and removing the eggs from a succeeding tank or tanks. It was determined that using multiple tanks and the apparatus for moving the eggs in and out of the tanks not only complicated the pasteurizing process, but substantially increased the cost thereof. In this latter regard, one of the hazards of pasteurizing eggs is that if during handling eggs break in a pasteurizing tank, then for food safety reasons, the process must be stopped, the tank drained, well-cleaned, and replenished with hot water. It was therefore recognized that it would be a substantial advantage to carry out the pasteurizing process at multiple temperatures but without the necessity of using multiple tanks. This would provide the advantages disclosed in the aforementioned patent that multiple temperatures of pasteurization can decrease the total time required for pasteurization and, thus, substantially reduce the pasteurization costs.
Further, the prior art considered it important that the eggs be removed from the pasteurizer as soon as a 5 log reduction of any Salmonella in the eggs is achieved. This is in order to prevent unwanted additional pasteurization, i.e. above the 5 logs safety requirement, which would adversely affect the functionality of the pasteurized eggs. However, this rather rigid requirement in the pasteurization, as it was perceived by the art, made it difficult to precisely achieve that 5 log reduction, while at the same time retaining the functionality of fresh raw eggs, without very careful control of the pasteurization process, along with expensive and extensive control devices. It would, of course, be of an advantage to the art to pasteurize eggs without such expensive control.
SUMMARY OF THE INVENTION
In regard to the above-discussed advantage of reducing the total pasteurization time, it was discovered that the total pasteurization time could be reduced by certain uses of multi-temperatures in the pasteurization process. These certain multi-temperatures include at least three different temperatures or temperature ranges, and especially where a first temperature(s) encountered by the eggs is at a higher temperature(s), a second temperature(s) encountered by the eggs is at a preferred pasteurization temperature(s), and a third temperature(s) encountered by the eggs is again at a higher temperature(s). More precisely, the first temperature(s) should be between about 139° F. and 146° F., the second temperature(s) should be between about 130° F. and less than 135° F., and the third temperature(s) should be between about 135° F. and 138° F. As a subsidiary discovery in this regard, it was found that, however, the time in which the eggs dwelled at the three different temperatures or temperature ranges must be different with a shorter time at the first higher temperature(s), a longer time at the second more desired pasteurization temperature(s), and a shorter time at the higher third temperature(s).
As another discovery in this regard, it was found, contrary to the understand
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