JPH0436660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a modified egg white that remains transparent and solution-like even when heated under high salt concentration or forms a transparent gel, and a method for producing the same. .

[Conventional technology]

Egg white is not only nutritionally and economically superior, but also has excellent functions such as gel forming ability, foaming ability, and emulsifying ability, and is widely used as a material for food processing.
However, since egg white forms a cloudy gel when heated, it cannot be used as it is as a raw material for liquid foods. Further, since heated egg white is accompanied by cloudiness, its use is restricted in food products characterized by transparency as described above and food systems in which cloudiness is inconvenient. Traditionally, other saccharides such as agar, alginic acid, and pectin, and animal proteins such as gelatin have been mainly used as transparent gel materials for confectionery and other products, but nutritional, economical, and functional There are aspects of sexuality that are not sufficient. Therefore, if transparency can be maintained even when heated,
It is likely that the use of egg whites will be further expanded. In addition to food, it can also be used as a material for cosmetics and pharmaceuticals. Transparent egg white, not as an ingredient but as a food form, is specifically found in the Chinese dish of pepper. This is the result of alkaline treatment of egg whites.
It is known that this occurs. However, alkaline treatment of proteins is accompanied by a decrease in the nutritional value of the proteins, the production of anti-nutritional factors, and is not preferred as an actual food processing method. A method for preparing transparent egg white by subjecting ovalbumin to limited hydrolysis using a proteolytic enzyme has also been reported. Although this method is a gentle processing method and is an excellent method, it is not economical at the current stage because it requires a large amount of expensive enzymes. Furthermore, there have been reports of prepared egg whites that can be prepared as transparent gels from which the conalbumin fraction has been completely removed from egg whites, but this method does not allow for the specific removal of conalbumin, which accounts for over 10% of egg whites. However, there remains a difficult problem in terms of what is needed. Furthermore, in any of these methods, when heating is performed in the presence of salt, a cloudy gel or a cloudy liquid is formed.

[Problem that the invention seeks to solve]

Therefore, the present inventors have made efforts to easily and inexpensively obtain modified egg white that can maintain a transparent liquid state or form a transparent gel even when heated under high salt concentration without reducing its nutritional value. Researched and completed this invention.

[Means for solving problems]

The present invention is a modified egg white obtained by dialyzing or diluting egg white against water to lower the ionic strength, removing the resulting precipitate, and then heating the supernatant in an acidic region, and a method for producing the same.

In the process of studying the heated egg white gel mechanism, the inventor discovered that the heated egg white gel had a turbidity and strength that were different from that of the egg white before heating.
It has been found that transparent solutions, transparent gels, cloudy gels, and cloudy suspensions can be prepared at will by adjusting the solvent conditions during heating, which are strongly influenced by pH and ionic strength.

In other words, if you adjust fresh egg white to a pH of 1 to 12 and heat it (e.g., 8℃, 1 hour),
If the pH is above 11, a brown transparent gel will be produced, but if the pH is below 10, a cloudy gel will be formed. On the other hand, when performing a similar experiment on egg whites dialyzed against water and removing the resulting precipitate, the result was a colorless transparent gel in the pH range of 2 to 4, a cloudy suspension in the pH range of around 6, and a cloudy suspension in the pH range of 10 to 20. Here, a brown transparent gel,
In other pH ranges, it forms a cloudy gel. It was found that transparent gels have high adhesive properties when prepared at pH 3.0 to 3.5, and extremely high gel strength when prepared at pH 3.5 to 4.0.
In addition, transparent gels are superior to cloudy gels in terms of water retention, which is an important gel characteristic. Furthermore, when the protein concentration is adjusted to 3% (W/V) or less and heated at around PH2.5, the state of a transparent solution is maintained. By performing dialysis treatment and adjusting the pH to an acidic range in this manner, heated transparent liquids and transparent gels can be obtained.

Dialysis in the present invention is performed by exchanging 20 times or more of water as an external solution three or more times every few hours. This reduces the ionic strength sufficiently, and the electrical conductivity of the albumen becomes approximately 100 μΩ ^-1 . Similar results are obtained by dilution with water instead of dialysis. That is, add 2 to 4 times the amount of water to egg whites, stir carefully at room temperature for 1 hour without foaming, remove the precipitate that has formed, adjust the pH to a range of 2.0 to 3.5, and heat to obtain a transparent gel. .

Next, add salt (NaCl) to the above dialyzed egg white,
When heated at similar pH values, a translucent gel forms at pH 2.5 to 3.0, a cloudy suspension forms at around pH 6, and a brownish transparent gel forms at pH 12, but all others form a white cloudy gel. That is, the turbidity increases in all regions as salt is added, resulting in an opaque gel.

Therefore, the above-mentioned egg white was dialyzed against water,
The protein concentration of the supernatant dialyzed egg white obtained by removing the precipitate was increased from 15 to 45 by adding water.
mg/ml, and then the pH of the solution was adjusted to pH 2.5 with hydrochloric acid, citric acid, or other acid, and heated (eg, 80° C., 1 hour). The egg white solution obtained by cooling this solution maintained its transparency even when salt was added. When salt was added to this transparent liquid and reheated, a transparent gel was formed. In other words, a heated egg white transparent gel was obtained even in the presence of salt. The gel thus prepared has low adhesion, high elasticity, and high strength.

Furthermore, as a result of analyzing the precipitate obtained by dialysis,
It has been found that this precipitate is a complex of egg white proteins mainly consisting of lysozyme and ovo macroglobulin, and the protein composition ratio of the supernatant is almost the same as that of the original egg white. That is, the supernatant mainly contains ovalbumin and conalbumin.

Example 1 Fresh egg whites were stirred at room temperature for 1 hour without foaming, and then dialyzed against 50 times the amount of water. The dialysis fluid was replaced three times every 3 hours. Final dialysis is 10
Time passed. Egg white after dialysis at 15000rpm
Centrifugation was performed at (20,000xg) for 10 minutes to obtain adjusted egg white as a supernatant. This adjusted egg white was diluted with water to adjust the protein concentration to 40 mg/ml and pH to 2.5, and was heated at 80° C. for 1 hour. This liquid was a clear solution. Salt (NaCl) was added to this solution at various concentrations from 0 to 400 mM, and the turbidity of the sample obtained by reheating at 80°C for 1 hour is shown in Figure 1 (Specimen 1: two-step heating). . For comparison, the supernatant at 15000 rpm was adjusted to pH 2.5 and 40 mg/ml, and NaCl was added to each concentration in the same manner.
The turbidity of the sample obtained by heating at 80°C for 1 hour is indicated by a white mark (Specimen 2: one-step heating). As is clear from this figure, for the sample (specimen 1) that was heated briefly before adding NaCl, the concentration was approximately 300mM.
It was shown that it remained transparent up to NaCl. Further, the hardness and adhesion of this sample were investigated and the results are shown in FIGS. 2 and 3. The hardness and adhesion of the gel were determined by pouring 40 ml of adjusted egg white into a 100 ml bottle with a lid, heating it at 80°C for 1 hour, and using Leonor.
Measured using texture mode of 3305 (Yamaden, Tokyo). From this figure, it was found that Sample 1, that is, the gel prepared by two-step heating, had less adhesion and became a hard, transparent gel when about 150 mM of NaCl was added. On the other hand, the gel (specimen 2) obtained by normal one-step heating after addition of NaCl was highly adhesive and was found to form a translucent or cloudy gel.

Example 2 Three times the amount of water is added to fresh egg whites, stirred at room temperature for 2 hours without foaming, and centrifuged at 3000 rpm for 100 minutes to obtain adjusted egg whites as a supernatant. HCI, or
Adjust the pH of this adjusted egg white from 1 to 12 using NaOH.
Place in a test tube for turbidity measurement with a diameter of 1 cm, and heat at 80°C for 1 hour. After cooling with running water for 1 hour, 10 mM of NaCl was added to each of these solutions, and the mixture was reheated at 80° C. for 1 hour, cooled in the same manner, and absorbance was measured. The results are shown in Figure 4. Even in these cases in the presence of salt, a transparent gel was formed in the pH range from 2 to 3.5. At pH 4 to 9, a cloudy gel or suspension was formed, and at pH higher than that, a colored transparent gel was formed.

〔Effect of the invention〕

The adjusted egg white of the present invention remains transparent and solution-like or forms a transparent gel even when heated in the presence of a high salt concentration, so it can be widely used as a raw material for not only foods but also cosmetics, medicines, and the like. In addition, this adjusted egg white is produced by simple processing of egg white, making it highly economical, and the protein composition of the adjusted egg white itself is almost the same as that of the raw egg white, making it nutritionally superior. It is.

[Brief explanation of drawings]

Figure 1 shows the relationship between NaCl concentration and turbidity in the adjusted egg white of the present invention, Figure 2 shows the relationship between NaCl concentration and hardness, and Figure 3 shows the relationship between NaCl concentration and hardness.
The figures show the NaCl concentration and adhesion, respectively, and Figure 4 shows the conditioned egg white (diluted in water) heated in the presence of salt.
Shows the relationship between PH and turbidity.

Claims (1)

[Claims] 1. Dialyze or dilute egg white against water without adjusting its pH to lower the ionic strength, remove the resulting precipitate, and then dilute the supernatant in an acidic range of pH 2.0 to 3.5. Adjusted egg white whose protein composition ratio obtained by heating is almost the same as the raw material. 2 Dialyze or dilute the egg white against water without adjusting its PH to reduce the ionic strength and remove the resulting precipitate, and then the resulting supernatant to a pH of 2.0 to 3.5 by adjusting its protein concentration. A method for producing adjusted egg white in which the composition ratio of proteins is almost the same as that of the raw material, which is characterized by heating in an acidic region.