Food or edible material: processes – compositions – and products – Fermentation processes – Of whole egg or yolk
Reexamination Certificate
2002-04-19
2003-12-09
Hendricks, Keith (Department: 1761)
Food or edible material: processes, compositions, and products
Fermentation processes
Of whole egg or yolk
C426S330100, C426S605000
Reexamination Certificate
active
06660312
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to egg yolk-containing, oil-in-water emulsified foods such as mayonnaise, tartar sauce and dressings, having reduced cholesterol contents.
BACKGROUND OF THE INVENTION
A demand for reduced-cholesterol foods has been increasing in recent years. However, oil-in-water emulsified foods such as mayonnaise, tartar sauce and dressings, whose main ingredient is egg yolk, inevitably contain at least a certain level of cholesterol. This is because egg yolk itself contains approximately 1.2% of cholesterol and also because some vegetable oils, which may be added as another essential ingredient, contain low levels of cholesterol.
Heretofore, there have been proposed mayonnaise-like foods which are produced without using egg yolk to attain the reduction of cholesterol level (Japanese Patent Laid-Open Publication No. 39341/1995, etc.). In the production of foods of this type, one cannot make use of the excellent emulsifying effect egg yolk has, and thus one should instead add emulsifiers or emulsion stabilizers such as starch, when required. Besides, these foods are lacking in the characteristic flavor and rich taste (superior taste) of egg yolk. Thus, yolk-free, mayonnaise-like foods that are satisfactory from the viewpoint of taste have not been obtained to date.
Further, there have also been proposed oil-in-water emulsified foods which are produced by using substantially the same level of egg yolk as in conventional mayonnaise but which have reduced cholesterol contents. For instance, a method for producing an oil-in-water emulsified food from reduced-cholesterol egg yolk is proposed in Japanese Patent Laid-Open Publication No. 23918/1996. According to this method, egg yolk and an edible oil are firstly mixed; from the resultant mixture, the edible oil is then removed by separation to obtain reduced-cholesterol egg yolk wherein approximately 40 to 90% of the cholesterol originally contained in the egg yolk has been extracted; and the reduced-cholesterol egg yolk is used in an amount of approximately 5 to 25% to produce an oil-in-water emulsified food. The oil-in-water emulsified food thus obtained however still contains at least 6×10
−3
% of cholesterol.
Furthermore, Japanese Patent Laid-Open Publication No. 137209/1999 describes a method for producing an oil-in-water emulsified food, characterized in that low-cholesterol egg yolk obtained by subjecting egg yolk to processing with supercritical carbon dioxide to reduce its cholesterol content by approximately 60 to 95% is used together with enzymatically processed egg yolk. In this method, however, enzymatically processed egg yolk, from which cholesterol has not been removed, is used in an amount of 0.5% or more, so that the resulting oil-in-water emulsified food still contains more than 6×10
−3
% of cholesterol.
Thus, there have not yet been succeeded in producing, using conventional levels of egg yolk, oil-in-water emulsified foods having reduced cholesterol contents of less than 6×10
−3
%.
Under these circumstances, we made studies to overcome the aforementioned drawbacks in the prior art, and came up with the idea of using, as an egg yolk ingredient of an oil-in-water emulsified food, low-cholesterol dried egg yolk according to Japanese Patent No. 3081038, obtainable by subjecting egg yolk to enzymatic processing, followed by processing with supercritical carbon dioxide. We continued our studies and found the following: if egg yolk is directly subjected to processing with supercritical carbon dioxide, almost all cholesterol contained in the egg yolk can be removed, but the egg yolk loses its emulsifying effect to a significant extent. This is probably because proteins and the like contained in egg yolk are severely damaged and modified in the course of the processing with supercritical carbon dioxide. However, we considered that if egg yolk is subjected to enzymatic processing for improving its emulsifying effect prior to the processing with supercritical carbon dioxide, it must be possible for us to prevent, to some extent, the egg yolk from losing its emulsifying effect in the course of the processing with supercritical carbon dioxide, whereby processed egg yolk containing almost no cholesterol can successfully be obtained while retaining the emulsifying effect. We further carried out our studies and came to have such a thought that if the processed egg yolk obtained in the above-described manner is used, an oil-in-water emulsified food containing almost no cholesterol can be obtained even if the egg yolk level is nearly equal to that in conventional mayonnaise.
To confirm this thought, we tried variously to prepare oil-in-water emulsified foods with the use of the egg yolk substantially free from cholesterol, obtained by subjecting egg yolk first to enzymatic processing and then to processing with supercritical carbon dioxide. The emulsified foods thus obtained were found to have poor emulsion stability, that is, they were readily separated into aqueous phase and oil phase during storage.
Meanwhile, Japanese Patent Laid-Open Publication No. 199559/1989 discloses a related technique. This technique, relating to a method for producing low-cholesterol dressings, is characterized in that egg yolk which has been subjected to processing for reducing cholesterol and also to phospholipase processing is used together with gelatinized starch. Admittedly, this publication describes the use of “modified egg yolk containing substantially no cholesterol.” However, with respect to the reduction of emulsion stability caused by the use of the egg yolk which has been subjected to processing for reducing cholesterol, the publication fails to describe any means for solving this problem, or even to mention this problem. The reason for this is probably as follows: as the dressings described in this publication have an egg yolk content lower than that of conventional mayonnaise, and contain gelatinized starch which is considered to be effective in improving emulsion stability, the inventors of the prior art did not notice at all that egg yolk loses its emulsifying effect to a significant extent when subjected to processing for reducing cholesterol.
Objects of the present invention are therefore to provide an oil-in-water emulsified food having a dramatically reduced cholesterol content but having a high egg yolk content, having emulsion stability high enough to prevent separation into aqueous phase and oil phase during storage, and having the characteristic flavor and rich taste (superior taste) of egg yolk, and to provide a method for producing such oil-in-water emulsified foods.
SUMMARY OF THE INVENTION
We made extensive studies in order to attain the above objects, and, as a result, have found that an oil-in-water emulsified food having high emulsion stability and scarcely undergoing separation during storage can be obtained if processing with supercritical carbon dioxide, to which the egg yolk already enzymatically processed is subjected, is so controlled that the resulting processed egg yolk can have a cholesterol content not lower than a specific level. The present invention has been accomplished on the basis of this finding.
The present invention, in a first aspect, therefore provides an oil-in-water emulsified food having an egg yolk content as calculated in terms of raw egg yolk of 2.8% or more, a content of cholesterol derived from egg yolk of 7×10
−4
% or more, and a total cholesterol content of less than 6×10
−3
%.
The present invention, in a second aspect, provides a method for producing an oil-in-water emulsified food, comprising the steps of subjecting an egg yolk fluid to enzymatic processing, thereby converting phospholipids contained in the egg yolk into lysophospholipids; subjecting the enzymatically processed egg yolk to processing for reducing cholesterol, thereby obtaining processed dry egg yolk still retaining at least 0.1% of cholesterol; and mixing the processed dry egg yolk with other ingredients in an amount of at l
Goto Masahiro
Hayashi Kunihiko
Ogino Yuji
Teraoka Satoshi
Tobita Masao
Hendricks Keith
Kewpie Kabushiki Kaisha
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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