Food or edible material: processes – compositions – and products – Fermentation processes – Of whole egg or yolk
Reexamination Certificate
2000-01-31
2001-11-06
Weier, Anthony J. (Department: 1761)
Food or edible material: processes, compositions, and products
Fermentation processes
Of whole egg or yolk
C426S614000
Reexamination Certificate
active
06312739
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a processed egg product and to a method for producing the same. More particularly, it relates to a processed egg product that can be imparted with heat stability when used in an emulsified food such as mayonnaise or dressings and to a method for producing the same.
2. Description of the Prior Art
Yolk is not only a food having a high nutritive value but also is an excellent emulsifier. Utilizing these characteristics, yolk has been used for producing many emulsified foods such as mayonnaise and dressings.
Recently, with the diversification of eating habits, mayonnaise and dressings and the like are used more often than ever in foods that are heated and processed. Accordingly, there has been an increasing demand for yolk applying for many types of foods, for example, retort salads, fillings, bread and the like.
For this reason, mayonnaise and dressings and the like that have heat stability are desired. However, those that use ordinary yolk as an emulsifier do not have sufficient heat stability. To improve this defect, a modified yolk has been proposed which has heat stability as a result of partial hydrolysis of yolk with a protease (Japanese Patent Kokai No. Hei 6-189713).
There is also a report that a protein complex consisting of lysophospholipids and a protein bonded to each other has an improved emulsifying ability so that its application is expected to extend to the field of foods and the like (Japanese Patent No. 2618540).
SUMMARY OF THE INVENTION
Recently, from the necessity that the requirement of microbiological stability of processed foods and the like be met more completely, there has been an tendency that yolk used as an emulsifier is required to have much higher heat stability. Although some improvement in heat stability has been recognized for the modified yolk obtained by the above, it is not satisfactory. There has been no reference to improvement in heat stability of the lysophospholipids-protein complex.
Therefore, an object of the present invention is to provide a processed egg product having heat stability that is further improved than that of modified yolk obtained by treating a yolk with a protease.
The present inventors have made intensive investigation with view to achieve the above object. As a result, they have found that a processed egg product obtained by partially hydrolyzing, with cause of protease, a yolk to which a saccharide and lysophospholipids have been added is more excellent than the conventional modified yolk subjected to a protease treatment only in view of usability of heat stability. The present invention has been achieved based on this finding.
Accordingly, the first aspect of the present invention provides a processed egg product obtained by partially hydrolyzing, with a use of protease, the yolk to which a saccharide and lysophospholipids have been added.
In the second aspect of the present invention, the saccharide may be a monosaccharide, a disaccharide or a hydrolysate of polysaccharide.
In the third aspect of the present invention, the saccharide may be glucose, glucose-fructose liquid sugar or starch syrup.
In the forth aspect of the present invention, the lysophospholipids may be one having a lyso conversion ratio of 50% or more.
The fifth aspect of the present invention provides a method for producing a processed egg product, comprising the step of partially hydrolyzing yolk containing 1 to 30% of a saccharide based on the weight of the yolk and 3 to 20% of lysophospholipids based on the weight of the yolk with 0.01 to 0.3% based on the weight of the yolk of a protease.
In the sixth aspect of the present invention, the saccharide may be a monosaccharide, a disaccharide or a hydrolysate of polysaccharide.
In the seventh aspect of the present invention, the saccharide may be glucose, glucose-fructose liquid sugar or starch syrup.
In the eighth aspect of the present invention, the lysophospholipids may be one having a lyso conversion ratio of 50% or more.
DETAILED DESCRIPTION OF THE INVENTION
The yolk used in the present invention may be a usual natural yolk liquid and is not particularly limited. For example, a yolk liquid obtained by breaking an egg and removing egg white is used generally. This may be diluted with water, if desired.
The saccharide may be either one of a monosaccharide, a disaccharide or a hydrolysate of polysaccharide. Examples of the monosaccharide include pentoses such as xylose, arabinose, and ribose, hexoses such as glucose and fructose. Examples of the disaccharide include sucrose, maltose, trehalose, lactose and the like. The hydrolysate of polysaccharide includes, for example, starch syrup and dextrin and the like. Also, glucose-fructose liquid sugar may be used.
The amount of saccharide to be added is suitably 1 to 30% by weight, preferably 3 to 20% by weight, based on the weight of yolk. If the weight of the saccharide to be added is less than 1% by weight, heat stability is not imparted sufficiently whereas if it exceeds 30% by weight, the viscosity of yolk increases abruptly and its handling tends to become difficult so that such an amount is not preferred.
The lysophospholipids to be added to yolk includes those obtained by hydrolyzing phospholipids extracted from yolk and soybean phospholipids or rapeseed phospholipids which are obtained as by-products at a production of vegetable oils with phospholipase A2. The ratio of lysophospholipids converted among the total phospholipids is called “lyso conversion ratio”. The lysophospholipids used in the present invention preferably are one having a lyso conversion ratio of 50% or more. The upper limit of the lyso conversion ratio is about 99%. If the lyso conversion ratio is less than 50%, it is difficult to impart sufficient heat stability to the yolk so that such a lyso conversion ratio is not preferable.
The amount of lysophospholipid to be added is preferably 3 to 20% by weight based on the weight of yolk. If the addition amount of lysophospholipid is below 3% by weight, it is difficult to impart sufficient heat stability to the yolk. On the other hand, the addition amount of above 20% by weight makes it difficult for lysophospholipids to be dissolved in yolk so that such an addition amount is not preferable.
The proteases used in the hydrolysis of yolk are not particularly limited and any of those derived from microorganisms, plants and living organisms can be used. In the main, endo type proteases are used. For example, there can be used those enzymes under trade names Proteases A, N, P, S, M, and B, Prolezer FG-F (Amano Pharmaceutical Co., Ltd.), Flavorzyme, Alkalase (Novonordics Co., Ltd.), Punchdase NP-2, Punchdase HP, Alloase AP-10 (Yakult Pharmaceutical Co., Ltd.), Denapsin 10P, Denazyme AP, Bioplase SP-15FG, edible purified papain (Nagase Biochemical Co., Ltd.), Protin P, Protin A, Samoase (Daiwa Kasei Co., Ltd.), etc. These may be used singly or two or more of them may be used in combination.
The addition amount of protease is preferably 0.01 to 0.3% by weight based on the weight of yolk. If the addition amount of protease is below 0.01% by weight, the partial hydrolysis of yolk is insufficient, so that heat stability is not imparted to the yolk sufficiently. On the other hand, the addition amount of protease exceeding 0.3% by weight is not preferred since in that case bitter, astringent or the like unpleasant taste tends to occur, resulting unpreferably in a decreased quality of yolk flavor.
The conditions of the protease treatment are as follows. First, for pH, treatment is possible at a pH in the range of 5 to 8. However, it is convenient to conduct the treatment at the pH native to yolks (about 6.5) and heat stability can be imparted to yolk under this condition.
As the temperature condition, 50 to 65° C. is preferred. At below 50° C., microorganisms tend to propagate while at temperature above 65° C. no further increase in efficiency of hydrolysis is obtained so that such a temperature is not preferable.
As for the treatment time, a time of 1 to 24 h
Hayashi Shigeko
Nakanishi Yoshikazu
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Knorr Foods Co., Ltd.
Weier Anthony J.
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