JPH01262773A - Quality improving agent for liquid seasoning - Google Patents

Abstract

PURPOSE:To obtain a safe and inexpensive quality improving agent containing a partially decomposed product of grain protein having a specific weight-average molecular weight, capable of effectively preventing degeneration change in quality, color change, precipitation, etc., of a liquid seasoning such as soy sauce by adding to the liquid seasoning. CONSTITUTION:A quality improving agent for a liquid seasoning consisting of partially decomposed product (preferably obtained by subjecting the grain protein to decomposition treatment with an alkali and then subjecting the treated product with an acid, enzyme, reducing agent or oxidant) of grain protein (preferably wheat gluten) is added to the liquid seasoning, preferably at an amount of 0.002-0.1wt.% to carry out quality improvement of the liquid seasoning.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a quality improving agent that prevents deterioration, discoloration, precipitation, etc. of liquid seasonings such as soy sauce and sauces.

(B) Conventional Technology Liquid seasonings such as soy sauce and sauces have the problem that when stored for a long period of time, they deteriorate or discolor, and produce precipitates and floating substances, reducing their commercial value.

These causes are not clear. However, for example, in soy sauce, the precipitate is called oli, and it is thought that the protein substances dissolved in the stock solution undergo thermal denaturation and coagulate, causing turbidity and settling. It is known that hydroquine butyl benzoate etc. act as a nucleus and promote the formation of sludge.

In addition, sauces contain trace metals, spices,
It is believed that pigments, proteins, etc. often cause deterioration, discoloration, and precipitation of products during or after the food processing process.

Conventionally, in order to solve these problems, soy sauce is heated rapidly and kept at 60-70°C for 40 minutes or more.
A method (Japanese Patent Publication No. 46-39078) is known in which sludge is generated and then heated at 80°C or higher for 2 minutes.
In addition, a method is known in which sucrose fatty acid ester is added as a quality improver to both soy sauce and sauces (
Special Publication No. 39-9294, Publication No. 37-16663
Publications, etc.).

(c) Problems to be Solved by the Invention However, the method disclosed in Japanese Patent Publication No. 46-39078 is not a desirable method as it complicates the manufacturing process, and furthermore, the formation of precipitates in the obtained soy sauce is largely prevented. However, the effect of preventing deterioration and discoloration may not always be sufficient. On the other hand, the method of adding a quality improver as disclosed in Japanese Patent Publication No. 39-9294 and Japanese Patent Publication No. 37-16663 is simple, but it is not necessarily satisfactory in terms of cost and quality improvement effect. Moreover, although it is approved as a food additive, it is itself a chemically synthesized product, so there are concerns about its toxicity.

This invention has been made under such circumstances, and in particular, it is an object to provide a quality improving agent for liquid seasonings that is safe and inexpensive and can substitute for conventionally widely used sucrose fatty acid esters, etc., and is imbued with quality improving effects. That is.

(d) Means and effect for solving the problem From the above viewpoint, the present inventors conducted intensive research and examination, and found that when a small amount of partial decomposition products of grain proteins such as gluten are added to soy sauce, sauces, etc. The quality of sucrose fatty acid esters has significantly improved, and this quality improvement effect has been shown to improve the quality of sucrose fatty acid esters, etc. We discovered a fact that is superior to this, and arrived at this invention.

Thus, according to the present invention, there is provided a quality improver for a liquid seasoning, which contains as an active ingredient a partially decomposed product of grain protein having a weight average molecular weight in the range of 500 to 110,000. .

The quality improving agent of this invention is usually added during the production of liquid seasonings such as shiura and sauce, and by adding the necessary amount, it can prevent deterioration, discoloration, precipitation, etc. that may occur in these seasonings. It acts to suppress and improve its quality. This quality improvement effect is superior to that of polyhydric alcohol fatty acid ester type surfactants such as sucrose fatty acid ester.

The grain protein partial decomposition product used in this invention is suitable for having a weight average molecular weight Mw of 500 to 110,000 when measured by gel filtration, and from the viewpoint of quality improvement effect, it is suitable to have a weight average molecular weight Mw of 500 to 50,000.
00 is preferred. In addition, if Mw is less than 500, the effect will be reduced because amino acids and their oligomers will be the main components, and if it exceeds 110,000, the properties will be similar to that of undecomposed substances, and the effect will be low, so it is not suitable. In addition, these molecular weights are 1600.6500°1600 as a standard substance.
Using polystyrene sulfonic acid sodium having a molecular weight of 0.650QO.88000, a gel filtration method was used (values measured by double-up) using Pharmacia's Sephadex G-75 or G-too as a carrier.

Note that in the present invention, grain protein refers to protein contained in grains, and examples of grains include barley (eg, wheat), corn, and beans (eg, soybean). Among the proteins contained in such grains, wheat protein, for example, contains glutenin and gliadin as main components and is usually called wheat gluten. Moreover, corn protein contains zein as a main component and is usually called corn gluten. These are all known substances and can be obtained by separating or extracting them from grains using conventional methods. For example, to obtain wheat protein (wheat gluten), if you add a small amount of water to wheat flour and knead it, then knead it in a large amount of water, the starch will stay in the water and the gluten content will become a sticky mass. remains. If this operation is repeated several times by changing the water, a grey-brown, viscous lump can be obtained. In order to prepare the partially decomposed product of the present invention, it is possible to use such lumps as they are, to use their dried products, or to use purified products, partially modified products, etc. good.

For example, wheat gluten is commercially available as a dried product and can be easily obtained. Commercially available corn gluten and soybean protein can be easily used. The protein may be either a crude product or a purified product, but it is preferable to use one containing 70% or more protein. stomach.

The grain protein partial decomposition product of this invention can be obtained by subjecting the above grain protein to a partial decomposition treatment.

In this partial decomposition process, the above grain proteins are treated with alkali,
This can be carried out by subjecting it to a decomposition treatment using an acid, an enzyme, a reducing agent, or an oxidizing agent.

The above decomposition treatment with alkali is suitably carried out by heating in a dilute aqueous alkali solution. Usually, an aqueous solution or aqueous dispersion of the substance to be decomposed is stirred at about 60 to 180°C for about 10 to 600 minutes in the presence of an alkaline agent such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, etc. It is appropriate to do so. Here, the aqueous solution or aqueous dispersion of the substance to be decomposed is 2 to 40
It is preferable to use 5% by weight of algae, and the amount of alkaline agent used is preferably 0.1 to 69% per 20 g of the substance to be decomposed.

On the other hand, decomposition treatment with an acid is suitably carried out by heating in a dilute acid aqueous solution. Usually, it is suitable to stir an aqueous solution or aqueous dispersion of the substance to be decomposed at a temperature of about 60 to 120°C for about 10 to 600 minutes in the presence of an inorganic acid such as hydrochloric acid or sulfuric acid or an organic acid such as acetic acid. There is. The quantitative conditions here are preferably the same as those for the alkaline hydrolysis described above.

Similarly, enzymatic decomposition treatment is suitably carried out in a dilute aqueous solution of an enzyme having protease activity;
A small amount of an enzyme such as pepsin, alkaline protease, papain, etc. is present in an aqueous solution or aqueous dispersion of the substance to be decomposed, and the enzyme is incubated at a temperature of about 10 to 60°C for about 60 to 600 minutes under the optimum pH condition of the enzyme. It is done.

Here, the quantitative conditions are preferably the same as above except that the amount of enzyme used is 0.02 to 5 g with respect to the substance to be decomposed 209.

Similarly, decomposition treatment using a reducing agent or oxidizing agent is suitably carried out in a dilute aqueous solution of the reducing agent or oxidizing agent, and sulfites, thiol compounds, and erythorbic acid are usually added to the aqueous solution or aqueous dispersion of the substance to be decomposed. The reaction is carried out at about 10 to 100° C. for 10 to 600 minutes in the presence of a small amount of a reducing agent such as hydranone or an oxidizing agent such as hydrogen peroxide or hypochlorite. The quantitative conditions at this time are preferably the same as those described above except that the amount of reducing agent or oxidizing agent used with respect to the decomposition object 209 is 0.1 to 5 g.

The above decomposition treatment may be carried out not only alone but also in combination of two or more kinds. In particular, according to the findings of the present inventors, the decomposition treatment with alkali (A) is an essential treatment, and the decomposition treatment (B) with one or more of acids, enzymes, oxidizing agents, and reducing agents is added to this. It has also been discovered that a decomposition product obtained by a combination of two or more decomposition processes is a new decomposition product different from conventional decomposition products, and is a suitable partial decomposition product for use in the present invention. . This novel grain protein partial decomposition product is characterized by the following physical properties.

(a) Weight average molecular weight (by gel filtration method) of 500~
It is in the range of 90,000.

(b) Ultraviolet absorption λmaX is around 260 to 28 Onm, and infrared absorption is 1400, 1630 and 3400 cm
It is around -'.

(C) The isoelectric point is in the range of 3.9 to 5.0.

(d) pH 1 pH (to lower the pH of 5% by weight aqueous solution of quartz 1004Q from 6 to 2, 2 to 2
53II2).

(e) It is soluble in water and insoluble in methanol, ethanol, acetone, and ether.

(f) Appearance is pale yellow to reddish brown powder.

(g) Color develops due to xanthoprotein reaction and ninhydrin reaction.

(h) Strong surface tension lowering ability (this product is added to pure water at 25°C with 0.0
The surface tension of pure water can be increased by 50% by adding 1%
dyne/Cm (measured with a Dunui surface tension meter).

(i) Strong emulsifying ability (by adding 1 g of this product, a water-soybean oil mixture containing at least 30% by weight of soybean oil)
Completely emulsify 09 (keep it uniformly emulsified for at least 10 minutes,
Preferably, it is maintained for at least 1 hour).

Such partial decomposition products are particularly suitable for the above-mentioned surface tension lowering ability (h).
It is distinguished from ordinary grain protein partial decomposition products in terms of emulsifying ability (i) and emulsifying ability (i).

Note that the order of the multistage decomposition processing is not particularly limited.

That is, raw materials such as wheat gluten are first subjected to alkaline decomposition treatment (A), and then decomposition treatment using the above-mentioned acid, enzyme, reducing agent, or oxidizing agent (B) (decomposition treatment other than alkali)
Alternatively, it may be subjected to two or more types of treatment, or the decomposition treatment may be performed in the reverse order. In addition, after first being subjected to decomposition treatment other than alkali (B), alkaline decomposition treatment (A
) and then again subjected to a decomposition treatment (B) using a substance other than an alkali. In addition, neutralization treatment may be performed as appropriate between each of these treatments. Among these, alkaline decomposition treatment (A) and acid decomposition treatment (B)
It is most preferable in terms of quality effect to combine the two.

The grain protein partial decomposition product-containing solution obtained in this manner can be used as it is as a quality improver for liquid seasonings, but it can also be used as a powder after drying. In addition, purified products that have been subjected to desalination treatment or decolorization treatment, such as by ultrafiltration, can also be used favorably.

The quality improver of the present invention is suitable for use by being added during the manufacturing process of soy sauce, sauces, etc., but may also be added after manufacturing. The amount added at this time is o, oot to the total amount of liquid seasoning in terms of quality improvement and quality stabilization.
A suitable amount is 0.5% by weight, and 0.002-0.
It is preferably 1% by weight. Here, the amount added is 0.00
If it is less than 1% by weight, it is not suitable because sufficient effects cannot be obtained, and if it exceeds 5% by weight, it is not suitable because it is not possible to expect an effect that exceeds the economical effect.

The quality improving agent of the present invention may contain other quality improving components in addition to the above-mentioned protein partial decomposition products. In particular, one preferred embodiment is to use it in combination with a polyhydric alcohol fatty acid ester type surfactant such as sucrose fatty acid ester or glycerin fatty acid ester, or lecithin. At this time, the blending ratio of protein partial decomposition product and surfactant is 1 = 8 ~
It is more preferable to use s:x (1Ki ratio) (preferably ◯:4 to 4:1) because a synergistic quality improvement effect can be obtained.

In addition, commonly used anti-fK agents such as ethanol, propionic acid, lactic acid, sorbic acid, dehydroacetic acid, and common salt may be used in combination, and this is also a preferred mode of use.

(Left below) (E) Examples This invention will be explained in more detail with the following Examples and Test Examples.

Examples 1 to 7 (Preparation of partially decomposed products of wheat gluten with alkali) 20 g of wheat gluten (reagent) manufactured by Wako Koyaku Kogyo Co., Ltd. was dissolved separately in the range of 0.2 to 4 g of caustic soda. Add to 100g of aqueous solution of
Each mixture was heated and stirred separately at a temperature and time within a range of 360 minutes. Neutralize these with hydrochloric acid and add pure water to a total of 200g.
Invention products Nos. 1 to 7 were obtained.

Table 1 shows the decomposition conditions and the average molecular weight (measured as Mw by gel filtration method) of the decomposed products.

Example 8~! 0 (Preparation of partial decomposition product of wheat gluten with acid) Three flasks containing 100 g of an aqueous hydrochloric acid solution equivalent to Ig, 2 g, and 4 g in terms of hydrogen chloride were injected with wheat gluten (reagent manufactured by Wako Saiyaku Kogyo Co., Ltd.). product) Add 20g,
1006C was heated and stirred for 160 minutes. After that, it was neutralized with caustic soda and made into a total amount of 200g with pure water, and Invention No. 8
I got ~10.

Table 2 shows the decomposition conditions and the average molecular weight of the decomposed products.

Example 11 (Preparation of enzymatic partial decomposition product of wheat gluten) Example! 20g of wheat gluten used in 0. IN = Add to a flask containing 150 g of hydrochloric acid solution to obtain an aqueous solution with a pH of 1.5, add 0.2 g of pepsin to this, and boil at 37°C for 90 min.
Allowed to react for minutes. Thereafter, it was neutralized with caustic soda and added to pure water to give a total of 11,200 g to obtain Invention Product No. 11. The average molecular weight was 60,000.

Real M! L Example 12 (Reducing agent for wheat gluten? Preparation of partially decomposed product) 20 g of the wheat gluten used in Example 1 was added to 100 g of an aqueous solution in which 4 g of sodium sulfite was dissolved, and the mixture was heated at 30°C for 6 hours.
After stirring for 0 minutes, the total amount was adjusted to 200g with pure water and the invention product No.
, I got 12. The average molecular weight was 79,000.

Examples 13 to 22 (Preparation of decomposition product by partial decomposition of wheat gluten with acid and subsequent partial decomposition with alkali) A 10% aqueous solution of the partial decomposition product of wheat gluten with acid was prepared under the same conditions as Examples 8 to 10. Put 100g of each into 8g of flask or autoclave, add 0.5 to 2g of caustic soda to each, and add 100g of each to 8g of flask or autoclave.
The mixture was heated and stirred at 00 or 150°C for 60 or 360 minutes. Thereafter, the mixture was neutralized with hydrochloric acid and purified with pure water to a total fi of 200 g to obtain invention products Nos. 13 to 20. caustic soda? Invention product No. 21 was obtained in the same manner as above except that sodium carbonate was used for peeling. The conditions for partial decomposition with acid were as follows: amount of hydrochloric acid added: 0.5 g, temperature: 80°C, time: 60 minutes.
The conditions for partial decomposition with alkali were as follows: the amount of caustic soda added was 0.
Invention product No. 22 was obtained in the same manner as above using 5g of the product, temperature of 80° C., and time of 30 minutes.

Table 3 shows the decomposition conditions and the average molecular weight of the decomposed products.

Examples 23 to 26 (Partial decomposition of corn gluten and soybean protein with acid, followed by partial decomposition with alkali, and preparation of decomposed products) Example using corn gluten manufactured by Nihon Shokuhin Kako (Hima) as a raw material! Invention product No. 23.24 was obtained by sequentially performing partial decomposition using acid and alkali under the same conditions as No. 8 and No. 13. The average molecular weights were 11,800 and 27,100, respectively.

In addition, using soybean protein obtained by defatting commercially available yuba with acetone as a raw material, partial decomposition was performed sequentially using acid and alkali under the same conditions as in Examples 18 and 13 to obtain Invention Product No. 25.2.
I got 6.

The average molecular weights were 12,000 and 29,000, respectively.

Examples 27 and 28 (Preparation of decomposition product by partial decomposition of wheat gluten with alkali and subsequent partial decomposition with acid) Obtained by partial decomposition of wheat gluten with alkali under the same conditions as Examples 5 and 6. 10% of the partially decomposed product
Aqueous solutions were prepared, and 100 g of each solution was placed in a 2 g flask, and 0.5 g and ig of hydrochloric acid in terms of hydrogen chloride were added to each solution, followed by heating and stirring at 100° C. for 60 minutes. After that, neutralize with caustic soda and add pure water for a total of 1200g.
Invention product 27.28 was obtained.

Table 4 shows the decomposition conditions and the average molecular weight of the decomposed products.

Example 29 (Preparation of enzymatic partial decomposition product of wheat gluten and subsequent alkali partial decomposition product) A 10% aqueous solution of enzymatic partial decomposition product of wheat gluten was prepared under the same conditions as in Example 11. , 1 g of caustic soda was added to 100 g of the mixture, and the mixture was heated and stirred in a flask for 60 minutes.

Thereafter, the mixture was neutralized with hydrochloric acid, and the total amount was adjusted to 200 g with pure water to obtain Invention Product No. 29.

The average molecular weight was 29,000.

Example 30 (Preparation of decomposed product by partial decomposition of wheat gluten with a reducing agent and subsequent partial decomposition with an alkali) A 10% aqueous solution of the partially decomposed product of wheat gluten with a reducing agent was prepared under the same conditions as in Example I2. , Caustic soda Ig was added to the solution, and the mixture was heated and stirred at 100° C. for 60 minutes in a flask. Thereafter, the mixture was neutralized with hydrochloric acid and the total amount was adjusted to 200 g with pure water to obtain invention product No. 30. The average molecular weight was 39,500.

Example 31 (Preparation of decomposed product by partial decomposition of wheat gluten with alkali and subsequent partial decomposition with enzyme (in the reverse order of Example 29)) Partial decomposition of wheat gluten with alkali under the same conditions as in Example 5. Prepare a 10% aqueous solution of the decomposed product, add reagent hydrochloric acid to 100g of it, and adjust the pH to 1.5.
An aqueous solution of was obtained, and 0.1 g of pepsin was added to this in a flask, and the mixture was reacted at 37° C. for 90 minutes. After that, it was neutralized with caustic soda and made into a total ff of 1200g with pure water.
, 31 were obtained. The average molecular weight was 24,500.

Example 32 (Preparation of decomposed product by partial decomposition of wheat gluten with alkali and subsequent partial decomposition with oxidizing agent) A 10% aqueous solution of wheat gluten partially decomposed with alkali was prepared under the same conditions as in Example 5, H to that 100g
! Hydrogen peroxide solution equivalent to 0.5 g in terms of 0.02 was added, and the mixture was heated and stirred at 10°C for 60 minutes. Thereafter, an amount of sodium thiosulfate (for masking hydrogen peroxide) equivalent to the remaining H2O2 was added, and the total amount was made up to 1200 g with pure water to obtain invention product No. J2. The average molecular weight was 37,000.

Example 33 Partial decomposition was carried out using an alkali under the same conditions as in Example 5 using corn gluten manufactured by Nihon Shokuhin Kaji Co., Ltd. as a raw material to obtain Invention Product No. 33.

The average molecular weight was 25,600.

Example 34 Under the same conditions as Example 8, 50 g of a pure aqueous solution containing 2 g of sodium sulfite (reducing agent) was added to 10% aqueous tilOOg of wheat gluten partially decomposed with acid, and heated at 30°C.
The mixture was stirred for 60 minutes. Thereafter, the total amount was adjusted to 200 g with pure water to obtain Invention Product No. 34. The average molecular weight was 53,000.

In addition, among the above invention products, the properties of the two-stage decomposition products of invention products Nos. 13 to 32 are shown in Table 5.

In the table, W on the raw material side means wheat gluten, C means corn gluten, and B means soy protein. Note that when the window is closed, the color of the measurement or test case will be tinted.

The following tests were conducted on the above invented product. In addition, the following comparison world comparison world No. I... Sucrose fatty acid ester (trade name 2DK ester F comparison world N manufactured by Daiichi Kogyo Seiyaku (Aji))
o, 2... Tests were conducted on soybean lecithin (trade name: Tonen Lecithin AY, manufactured by Hounen Oil Co., Ltd.).

Test Example 1 (Soy sauce quality improvement test) [Test method] Heat the sample soy sauce (!) to 80°C for 10 hours and add the specified amount of the sample. Preservative butyl p-hydroxybenzoate 20
1? Add and mix to dissolve. 200. Place in an IIQ beaker and leave at room temperature for 20 or 100 days, and observe the formation of suspended matter. After 100 days, the 8 oils were discarded and the state of the precipitate remaining in the heater was observed using rIA.

As the sample soy sauce oil, a 1:1 mixture of Kikkoman soy sauce [Koikuchiko and naturally brewed soy sauce [Tezukuri Sho 7]] was used.

[Sample product invention product No. 8.11, 13, 16.23, 25, 27
．． 30J1 and 34, and comparative field N001 and 2 [Test results] The above results are shown in Table 6.

(Margin below) In addition, evaluation of floating matter and sediment in Table 6 is based on the following criteria.

Evaluation of floating substances Evaluation of sediments◎・・・
...No floating matter at all ◎...No sediment at all ○...There is a slight amount of oily floating matter
○... Some fine crystals △... White crystals floating in the building △... Somewhat large crystals fk present X... White crystals There are floating objects
×: A large amount of slightly large crystals [Considerations] As shown in Table 6, the addition of the invention significantly suppresses or prevents quality deterioration due to the formation of suspended matter and precipitates, and It can be seen that the quality improvement effect is superior to that of the comparative world.

Test Example 2 In the same manner as Test Example 1, invention product No. 16 and comparison world No.
, L (sucrose fatty acid ester) or Comparative Industry No. 2 (soybean lecithin) was evaluated for quality improvement effect. The results are shown in Table 7.

(Margins below) [Consideration] As described above, it can be seen that the combined use of the invention product with Sea I saccharide fatty acid ester and soybean lecithin is also useful for improving quality, and in particular, a synergistic effect is exhibited.

Test Example 3 (Sauce quality improvement test) Sauces often cause product deterioration, precipitation, discoloration, etc. due to trace metals, spices, pigments, proteins, etc. contained therein. The effectiveness of preventing these phenomena was investigated using the method described below for the invented product.

[Test method] A predetermined amount of the sample is added to a sample source of 18 mQ, the temperature is adjusted to 20xσ with tap water, and the appearance is observed after being left for 100 days.

The sample sauce was prepared using onions, tomato puree, pepper, etc. according to the method described in "Worcestershire Sauce 34" published by Jinshokan, edited by Kosuke Kosukezawa, Food Processing Training.

[Sample Invention Product No. 2.10, 11, 16, 17.24, 25
．． 30 and 34 and comparative field Nos. 1 and 2 [Test results] The above results are shown in Table 8.

(Margin below) The evaluation criteria are as follows.

Evaluation of liquid surface condition〉 ○...Uniform with no separation △...Slight separation but unclear boundary ×...
Separated (red on the liquid surface) Evaluation of precipitate > Q: No precipitate at all △: Slight precipitate ×: Produced in precipitating tapeworms [Consideration section] As shown in Table 8, it can be seen that the invented products exhibit excellent sauce quality improvement effects.

Test Example 4 In the same manner as Test Example 3, invention product No. 16 and comparative product No.
, 1 (sucrose fatty acid ester) or comparative product No. 2 (soybean lecithin) was evaluated. The results are shown in Table 9.

[Discussion] As described above, it can be seen that the combined use of the invented product with sucrose fatty acid ester and soybean renotin is also useful for quality improvement effects, and in particular, a synergistic effect is exhibited.

(f) Effects of the Invention According to the quality improving agent of the present invention, it is possible to significantly suppress or prevent quality deterioration of liquid seasonings, particularly quality deterioration due to the formation of suspended matter or precipitates.

The active ingredient, a partially degraded product of grain protein, is food or food-like, so it is extremely useful in that it is non-toxic.
1J, has improved safety as a food additive, and is inexpensive.

Therefore, the quality improver of the present invention is extremely useful as an additive for liquid seasonings such as soy sauce and sauces.

Claims (1)

[Scope of Claims] 1. A decomposition product of grain protein with a weight average molecular weight of 5.
A quality improver for a liquid seasoning comprising a partially decomposed product ranging from 0.00 to 110,000 as an active ingredient. 2. The quality improving agent according to claim 1, wherein the grain protein is wheat gluten, corn gluten or soybean protein. 3. Claim 1, wherein the partially decomposed product is obtained by subjecting grain protein to a decomposition treatment using one or a combination of two or more of decomposition treatments using an alkali, an acid, an enzyme, a reducing agent, or an oxidizing agent. Quality improver as described. 4. The partial decomposition product is obtained by subjecting grain protein to partial decomposition treatment using one or a combination of two or more of decomposition treatment with an alkali (A) and decomposition treatment with an acid, an enzyme, a reducing agent, or an oxidizing agent (B). The quality improving agent according to claim 1, which is obtained by. 5. The quality improving agent according to claim 1, wherein the partial decomposition product is obtained by subjecting grain protein to partial decomposition treatment using a combination of decomposition treatment with an alkali and decomposition treatment with an acid. 6. The quality improver according to claim 1, which has a weight average molecular weight of 500 to 50,000. 7. The quality improving agent according to claim 1, wherein the liquid seasoning is soy sauce or sauces. 8. The quality improving agent according to claim 1, further comprising a polyhydric alcohol fatty acid ester type surfactant or lecithin. 9. The quality improving agent according to claim 8, wherein the protein partial decomposition product and the polyhydric alcohol fatty acid ester type surfactant or lecithin are blended in a weight ratio of 1:6 to 6:1. 10. Polyhydric alcohol fatty acid ester type surfactant,
The quality improving agent according to claim 9, which is a sucrose fatty acid ester and/or a glycerin fatty acid ester. 11. The quality improving agent according to claim 1 or 8, which is used by adding 0.001 to 0.5% by weight into a liquid seasoning.