JP5614645B2 - Method for producing acidic water-soluble protein and acidic water-soluble protein - Google Patents

Description

  The present invention relates to a method for extracting wheat protein, and more particularly, to a method for producing acidic water-soluble protein from wheat gluten and the acidic water-soluble protein.

  Gluten, which is a wheat protein, can be fractionated into gliadin that is soluble in ethanol and glutenin that is insoluble, with an aqueous ethanol solution of 50 to 70% by volume. This extraction of gliadin and / or glutenin requires an apparatus for recovering ethanol as a solvent in order to perform the operation in the presence of high-concentration ethanol, and all of the equipment that performs these operations must be explosion-proof devices. There are many problems such as, and there is a problem that the equipment cost becomes high.

  Therefore, some proposals have been made to solve these problems. In Patent Nos. 2945542 and 2896422, citric acid or the like can be used even in an aqueous solution having a low ethanol concentration of 1 to 20% by volume. It is shown that gliadin and / or glutenin can be extracted from gluten of wheat protein by dissolving 0.01 to 5.0 wt / vol% of the organic acid in the ethanol aqueous solution ( Patent Documents 1 and 2).

  On the other hand, in European Patent No. 684164, an extraction method using an aqueous ethanol solution having a concentration of 30 to 70% by volume, an aqueous solution of isopropyl alcohol or n-propanol having a concentration of 10 to 20% by volume, or an aqueous acetone solution having a concentration of 20 to 50% by volume. Shows that a fraction having a gliadin concentration of 80% by weight or more was obtained. Furthermore, it is described that a fraction of gliadin having a concentration of 5 to 30% by volume and having a concentration of 50% by weight or more can be obtained by using an ethanol acidic aqueous solution having a pH of 3.5 to 5.5. . In addition, acetic acid, citric acid, malic acid, lactic acid, adipic acid, fumaric acid, tartaric acid, gluconic acid, phosphoric acid, and phytic acid are shown as usable acids at this time (Patent Document 3).

  In Japanese Patent No. 2945279, the fraction of gliadin has properties such as the water absorbency and mildness of the powder depending on the type of solvent used for extraction from wheat gluten, the solvent removal method and the powdering method. It is shown that they are greatly different, and it is described that these greatly affect the water absorption speed, gluten formation time, and dough physical properties during gluten formation. Furthermore, when extracted with a low-concentration aqueous ethanol solution, it is superior in water absorption and mildness compared to when extracted with a high-concentration aqueous ethanol solution. Furthermore, it has been shown that the frozen dough can be prevented from being frozen and denatured, and the fired product can be produced without hardening, and the aging of the fired product is suppressed (Patent Document 4).

  In the examples in the literature, gliadin is fractionated under the following conditions. That is, 1 kg of powdered active gluten (wheat gluten) was added to an acidic ethanol aqueous solution in which 2 g of citric acid was dissolved in 10 L of 10 vol% ethanol aqueous solution, extracted at room temperature for 2 hours, and then separated by a centrifuge. The supernatant is dried using a spray dryer to obtain 360 g of dry powder of the gliadin fraction.

  The components of the dry powder are 4% by weight of moisture and 90% by weight of protein, and the ratio of gliadin to the total protein is 80% by weight. Moreover, it is shown that pH of 1/40 aqueous solution is 3.9 and the amount of citric acid is 4.5 weight%.

  On the other hand, in the above literature, gliadin fraction is also fractionated by adding 1 kg of powdered active gluten to a 70% by volume ethanol aqueous solution, the solvent is removed from the obtained crude gliadin under vacuum to obtain a dried product, To obtain 180 g of crude gliadin powder (referred to as gliadin 1). Further, the crude gliadin is fractionated again with 99.5% by volume ethanol, and after collecting the precipitate, gliadin is purified by repeating the operation of dissolving with 70% by volume ethanol aqueous solution. After drying under vacuum as described above, 60 g of purified gliadin powder (referred to as gliadin 2) was obtained.

  The components of gliadin 1 and 2 are 3 wt% moisture and 90 wt% protein in gliadin 1, and the ratio of gliadin to the total protein is 95 wt%. The pH of the 1/40 aqueous solution is 6.7, and the acidity (acidity titration with hydrochloric acid) is 0.1% by weight or less. On the other hand, in gliadin 2, the water content is 3% by weight and the protein is 95% by weight, the ratio of gliadin to the total protein is 99% by weight, the pH of the 1/40 aqueous solution is 6.8, and the acidity (acidity titration with hydrochloric acid) is 0.1. It is shown that it is less than wt%.

  In the above-mentioned document, a bread making test using gliadin 1 and gliadin 2 as comparative examples for gliadin fraction dry powder prepared using an acidic ethanol aqueous solution containing citric acid has also been studied, and the gliadin fraction dry powder is gliadin. Compared with 1 and 2, it shows that the expansibility is improved, aging is suppressed, and crumb is hardened by freezing.

  However, in these techniques, there is no change in using alcohol that is flammable as a solvent, and there are problems with the explosion-proof measures of equipment related to solvent recovery and extraction operations and the remaining organic solvent of the extracted fraction, for example, Residual alcohol odor is not solved.

  On the other hand, in European Patent Nos. 684164 and 4171521, a pH of 0.1 to 10% by weight / volume containing one or more of citric acid, lactic acid, malic acid, acetic acid, phosphoric acid and salts thereof. Extraction methods using 5 or less aqueous solutions are disclosed (Patent Documents 3 and 5). However, details of the extraction conditions and the obtained extract are not disclosed.

  Patent No. 4208712 discloses a method for producing a gliadin-rich fraction and a glutenin-rich fraction from gluten in an aqueous medium in the presence of an acid (Patent Document 6). However, if the shear strength and / or mixing time is not appropriate, the desired fraction cannot be obtained. In order to obtain the desired fraction, it is necessary to adjust the setting of the decanter centrifuge. There is.

Japanese Patent No. 2945542 Japanese Patent No. 2896422 European Patent Application No. 685164 Patent No. 2945279 Japanese Patent No. 4171521 Japanese Patent No. 4208712

  The object of the present invention is to prevent the explosion of the equipment related to the recovery and extraction operation of the solvent when the conventional flammable solvent alcohol is used and the problems with the residual organic solvent of the extracted fraction, such as the residual alcohol odor. An object of the present invention is to provide an industrial acidic water-soluble protein production method using wheat gluten as a raw material, which is not limited to production equipment such as shearing conditions and separation equipment, and to provide a protein having excellent bread-making characteristics. .

  As a result of diligent research to solve the above problems, the inventors of the present invention do not require a flammable solvent alcohol and are not limited to extraction equipment such as a special shearing device, and have excellent bread-making characteristics mainly composed of gliadin. The present inventors have found the optimum conditions for the wheat gluten fractionation method capable of easily obtaining the fraction industrially, and completed the present invention. That is, the present invention relates to a method for producing an acidic water-soluble protein, wherein protein soluble in an acidic aqueous solution is extracted from wheat gluten, and the acidic aqueous solution is 1.5 to 3 based on the dry weight of the wheat gluten. 0.0% by weight of an organic acid, the organic acid is composed of at least lactic acid and malic acid, the weight ratio of lactic acid to malic acid is lactic acid / malic acid = 83-18 / 17-82, and contains a flammable solvent In addition, the acidic aqueous solution is used in an amount of 8 to 12 times the dry weight of the wheat gluten, and the pH of the acidic aqueous solution in which the wheat gluten is dispersed at the time of extraction is 3.7 to 4.3. The present invention provides a method for producing an acidic water-soluble protein and the acidic water-soluble protein.

  According to the method for producing acidic water-soluble protein according to the present invention, industrial production of acidic water-soluble protein is facilitated, and the obtained protein can satisfy both yield and bread-making characteristics. That is, according to the present invention, since a flammable solvent such as ethanol that has been used conventionally is not used, there is no problem that the solvent recovery device or the entire device must be an explosion-proof device. There is no need for a separation apparatus, and the yield of the protein is high, which is very advantageous industrially. The protein obtained by the present invention exhibits a high effect in practical use such as improvement of bread making. .

  Hereinafter, embodiments of the present invention will be described in detail. The wheat protein used for the production of the acidic water-soluble protein of the present invention may be either gluten (raw gluten) separated from wheat flour by a conventional method or a dried powder (vital gluten).

  The acidic aqueous solution used in the present embodiment uses an aqueous solution containing at least lactic acid and malic acid as organic acids and not containing a flammable solvent alcohol. Further, as the acidic aqueous solution, an aqueous solution obtained by mixing lactic acid and malic acid with an organic acid such as citric acid, acetic acid or phosphoric acid can also be used.

  In this embodiment, the acidic aqueous solution used for extraction is obtained by dissolving 1.5 to 3.0% by weight of the organic acid relative to the dry weight of wheat gluten. If the organic acid concentration is lower than this, the solid content contained in the supernatant after solid-liquid separation decreases, and the solid content yield of the acidic water-soluble protein decreases. On the other hand, when the organic acid concentration is higher than this, the gluten component insoluble in the acidic aqueous solution, that is, the glutenin fraction swells, and the solid-liquid separation ability decreases.

  By the way, wheat gluten is composed of gliadin and glutenin. Gliadin contributes to viscosity (extensibility of flour dough) and glutenin contributes to elasticity (tensile strength of flour dough). That is, it is known that gliadin acts positively and glutenin acts negatively on gluten extensibility.

  On the other hand, lactic acid is also known to act on wheat gluten during bread making to improve the extensibility of the dough.

  In the extraction of the acidic water-soluble protein with the acidic aqueous solution in the present embodiment, a small amount of low molecular weight glutenin that negatively affects extensibility is also extracted. However, by using lactic acid for extraction, lactic acid is also glutenin simultaneously. It was found that lactic acid counteracts the elasticity of glutenin.

  In addition, the use of lactic acid in this embodiment is advantageous in terms of improving the dispersibility of the gluten and increasing the solid content concentration of the acidic water-soluble fraction when extracting the acidic water-soluble fraction from wheat gluten. However, it has also been found that the insoluble glutenin fraction is swollen and the solid-liquid separation ability by centrifugation is reduced.

  On the other hand, the use of malic acid in the present embodiment suppresses swelling of the insoluble glutenin fraction when extracting the acidic soluble fraction from wheat gluten, so that solid-liquid separation becomes easy and the amount of solution after separation Found to increase.

  In addition, the use of malic acid does not increase the soluble mass of the soluble fraction in the solution, so the solids yield is reduced, and in the drying process, a thin solution of the soluble fraction must be dried in large quantities. It was found to increase the load.

  Therefore, the optimum organic acid concentration and the weight ratio of lactic acid / malic acid in this embodiment were examined, and the results are shown in Table 1.

  The test method is to disperse 10 g of commercially available powdered gluten (protein 75 wt% (dry matter equivalent value), moisture 6 wt%) in 90 g of an acidic aqueous solution containing an organic acid having the concentration and lactic acid / malic acid ratio shown in Table 1. The mixture was extracted with stirring at room temperature (25 ° C.) for 30 minutes. For the stirring, a mixer having a stirring blade was used, and the rotation speed was 600 rpm. p. m. I went there. This was centrifuged (2,700 G) with a centrifuge and evaluated by observing the separated state.

  The evaluation was based on the state of separation after centrifugation as an index, and the case where the amount of the supernatant was 45% by volume or higher was allowed (◯ mark), and the case where it was 44% by volume or lower was not possible (x mark). In addition, the solid content yield is calculated from the solid content (Brix) of the supernatant after centrifugation, and the value can be 45% by weight or more (○ mark), and 44% by weight or less (× mark). It was.

  As shown in Table 1, when the organic acid contained in the acidic aqueous solution is only lactic acid, the yield of the solid content contained in the supernatant after solid-liquid separation is unsuitable with 44% by weight or less. When the total organic acid concentration is lower than 1.5% by weight, the solid content yield is low, while the total organic acid concentration is 3.0. It has been found that when the content is higher than% by weight, the swellability of the insoluble gluten component in the acidic aqueous solution is increased, the solid-liquid separation ability is lowered, and the separation state is deteriorated. On the other hand, regarding the ratio of lactic acid and malic acid contained in the acidic aqueous solution, the solid content yield was 44% by weight or less when the weight ratio of lactic acid / malic acid was 17/83, which was inappropriate.

  From the above results, when the weight ratio of lactic acid to malic acid used in this embodiment is suitable in the range of lactic acid / malic acid = 83 to 18/17 to 82, and the weight ratio of lactic acid is higher than this, It was found that the solid-liquid separation state deteriorates, while the extraction efficiency of the acidic water-soluble protein decreases when it is low, and the yield of the acidic water-soluble protein decreases.

  Table 2 summarizes the evaluation of solid-liquid separation by the combination of lactic acid and malic acid concentration (% by weight) contained in the acidic aqueous solution used for extraction. That is, the amount of the supernatant after centrifugation is 45% by volume or more, and the solid content yield by organic acid aqueous solution extraction is calculated from the solid content (Brix) of the supernatant after centrifugation, and the value is A case where it was 45% by weight or more was shown as “good” by “◯”. On the other hand, the amount of the supernatant after centrifugation is 44% by volume or less, or the solid content yield by organic acid aqueous solution extraction is calculated from the solid content (Brix) of the supernatant after centrifugation, and the value is 44 wt. % Or less is indicated as x. The numbers at the bottom of the circles and x shown in Table 2 are the numbers in Table 1. It corresponds to.

  As shown in Table 2, the range of lactic acid concentration suitable for the purpose of the present invention is 0.5 to 2.5% by weight, and the range of malic acid concentration is 0.5 to 2.0% by weight. I understood.

  Extraction in the present embodiment is performed by adding 1.5 to 3.0% by weight of an organic acid aqueous solution with respect to the dry weight of wheat gluten, and the weight ratio of lactic acid and malic acid to lactic acid / malic acid = 83 to 18/17 to 82. In this state, gluten is dispersed in the acidic aqueous solution dissolved in step 1. The pH of the gluten dispersion at that time is in the range of 3.7 to 4.3.

  As extraction conditions in this embodiment, 8 to 12 times the amount of the wheat gluten dry matter weight, more preferably 9 to 10 times the amount of the extraction solution is used. In addition, when the extract solution is small, the organic acid concentration of the extract solution is high, which is not suitable because the swelling of the acid-insoluble portion of the gluten component dispersed in the acidic aqueous solution is increased and the solid-liquid separation ability is reduced. . On the other hand, when the extraction solution is large, the organic acid concentration of the extraction solution is low, so that solid-liquid separation is easy and soluble, that is, the amount of solution after solid-liquid separation increases, It is unsuitable because it becomes low and the drying load at the time of drying increases.

  Extraction of acidic water-soluble protein with an acidic aqueous solution may be performed simply in an extraction tank equipped with a stirring blade or the like, and is not limited to the equipment and mechanical capacity such as the number of rotations during stirring.

  The temperature of the extraction solution is room temperature, and the extraction time is preferably 5 minutes to 180 minutes. The solid-liquid separation after the extraction step can be performed after standing for several hours to overnight. Is not particularly limited.

  The fraction of the gluten dispersion can be fractionated into a supernatant (acid soluble fraction) and a precipitate (acid water insoluble fraction) by operations such as centrifugation or filtration.

  The amount of the supernatant obtained after solid-liquid separation of the gluten dispersion is 45 to 65% by weight of the gluten dispersion, and the supernatant, that is, the acidic water soluble fraction, is 45 to 60% by weight of the amount of gluten charged. Is dissolved. That is, the yield of acidic water-soluble protein is 45 to 60% by weight.

  The soluble fraction containing acidic water-soluble protein obtained by solid-liquid separation can be used after being dried into powder. In addition, as a concentration method of a soluble fraction, it can concentrate using vacuum concentration, freeze concentration, membrane concentration, and the method which combined these. The drying can be performed by any method, but freeze drying or spray drying is preferable.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

1. Examination of the organic acid concentration of the acidic aqueous solution used for extraction Using an acidic aqueous solution containing lactic acid and malic acid as organic acids and a weight ratio of 50/50, the optimum total organic acid concentration was examined, and the results were obtained. It is shown in Table 3.

  The test method was 30 g of commercially available powdered gluten (protein 75 wt% (dry matter equivalent value), moisture 6 wt%), and the total organic acid concentration was 1.0 wt% (Comparative Example 1) based on the weight of gluten dry matter. Dispersed in 300 g of an acidic aqueous solution containing 1.5 wt% (Example 1), 2.0 wt% (Example 2), 3,0 wt% (Example 3) or 3.5 (Comparative Example 2) wt% Extraction was performed by stirring at room temperature (25 ° C.) for 30 minutes. In addition, the stirring uses a mixer with a stirring blade, and the rotational speed is 600 rpm. p. m. I went there. Further, the pH of the gluten dispersion after extraction was measured, and the value is shown in Table 3.

  The gluten dispersion was centrifuged (2,700 G) to fractionate into a supernatant containing acidic water-soluble protein and a precipitate (insoluble fraction). The amount of the supernatant obtained after this centrifugation was determined and shown in Table 3 as the weight percent with respect to the gluten dispersion. The solid content yield (% by weight) of the supernatant was calculated from the solid content (Brix) of the supernatant after centrifugation.

  Furthermore, the supernatant containing the acidic water-soluble protein fractionated above was freeze-dried and then powdered with a pulverizer to obtain a dried product.

  As shown in Table 3, the wheat gluten acidic aqueous solution soluble fraction amount, that is, the amount of the supernatant was 55 to 65% by weight of the gluten dispersion in all cases of Examples 1 to 3, and the solid yield Was from 50 to 55% by weight.

  On the other hand, in Comparative Example 1, the solid concentration in the supernatant after centrifugation was as low as 5.2% by weight, and the drying load during drying increased and the solid content yield of acidic water-soluble protein was 39% by weight. % And a low value.

  On the other hand, in Comparative Example 2, the solid-liquid separation ability by centrifugation was low, the amount of the supernatant was as small as 44% by weight, and the solid yield of acidic water-soluble protein was as low as 40% by weight.

  Therefore, the optimum total organic acid concentration of the acidic aqueous solution used for extraction was found to be 1.5 to 3.0% by weight based on the weight of gluten dry matter.

2. Examination of the weight ratio of lactic acid / malic acid in the acidic aqueous solution used for extraction The organic acid concentration was 2.0% by weight with respect to commercially available powdered gluten (75% protein (dry matter equivalent), water 6% by weight). Acidic aqueous solubility from wheat gluten using lactic acid / malic acid weight ratio of 85/15 (Example 4), 50/50 (Example 2) or 20/80 (Example 5) in the aqueous solution Fractions were extracted. As a comparative example, an aqueous solution having a lactic acid / malic acid weight ratio of 100/0 (Comparative Example 3) or 10/90 (Comparative Example 4) was used.

  As in the test method, 30 g of powdered gluten was dissolved in 2.0% by weight of an organic acid (lactic acid / malic acid = 85/15, 50/50 or 20/80) based on the weight of the gluten dried product. Extraction was carried out by dispersing in 300 g of the aqueous solution and stirring at room temperature (25 ° C.) for 30 minutes. In addition, the stirring uses a mixer with a stirring blade, and the rotational speed is 600 rpm. p. m. I went there. Further, the pH of the gluten dispersion after extraction was measured, and the value is shown in Table 4.

  The gluten dispersion was centrifuged (2,700 G) to fractionate into a supernatant containing acidic water-soluble protein and a precipitate (insoluble fraction). The amount of the supernatant obtained after this centrifugation was determined and shown in Table 4 as the weight percent with respect to the gluten dispersion. The solid content yield (% by weight) of the supernatant was calculated from the solid content (Brix) of the supernatant after centrifugation.

  Furthermore, the supernatant containing the fractionated acidic water-soluble protein was freeze-dried and then powdered by a pulverizer to obtain a dried product.

  As shown in Table 4, the wheat gluten acidic aqueous solution soluble fraction amount, that is, the amount of the supernatant was 55 to 62% by weight of the gluten dispersion in all cases of Examples 2, 4 and 5, The yield was 52 to 55% by weight.

  On the other hand, in the case of Comparative Example 3, the solid-liquid separation ability by centrifugation was low, the amount of the supernatant was as small as 42% by weight, and the solid yield of acidic water-soluble protein was as low as 39% by weight. In the case of Comparative Example 4, the solid concentration in the supernatant after centrifugation is as low as 6.0% by weight, and the drying load during drying increases and the solids yield of acidic water-soluble protein increases. The value was as low as 43% by weight.

  Therefore, it was found that the appropriate ratio of lactic acid / malic acid in the acidic aqueous solution used for extraction was 85-20 / 15-80. This result proved that it was within the numerical range of 83-18 / 17-82 shown by the result of the above-mentioned Table 1.

  Moreover, as for the dried material obtained in Examples 1-5, 70 weight% or more of the solid substance contained in the soluble fraction at the time of fractionating with 70 volume% ethanol aqueous solution was contained in the solid substance in all. .

3. Organic acid composition and concentration contained in extracted acidic water-soluble protein Total organic acid amount per dry matter weight contained in acidic water-soluble protein fractions prepared in Examples 1 to 5, lactic acid amount and malic acid amount, and lactic acid / The weight ratio of malic acid is shown in Table 5. In addition, it showed also about the case of Comparative Examples 1-4.

  Analytical conditions for organic acid, lactic acid and malic acid are as follows. That is, the sample used was a solution obtained by adding 50 ml of distilled water to 1 g of a dried product of acidic water-soluble protein and filtering the solution stirred at room temperature for 30 minutes with a membrane filter (0.45 μm). The measurement conditions were TSK-Gel DEAE 2SW 4.6 × 250 for the column, LC-6A (manufactured by Shimadzu Corporation) for the pump, and SPD-6A (manufactured by Shimadzu Corporation) for the detector. Measurement was performed at a wavelength of 210 nm. The mobile phase used was 0.04M ammonium phosphate / MeCN (75/25) pH 6.5, and the flow rate was 1.0 ml / min. The analysis temperature was room temperature.

  Each of the acidic water-soluble proteins of Examples 1 to 5 contains 1.0 to 3.0% by weight of lactic acid and malic acid, and the ratio of lactic acid to malic acid is lactic acid / malic acid = 83 to 18 / 17-82. On the other hand, Comparative Examples 1-4 were all outside this range. This result proved that the examples were within the numerical ranges shown in the results of Tables 1 and 2 above.

4). Breadmaking test In order to evaluate breadmaking characteristics, bread dough was prepared in the process shown in Table 7 using the recipe shown in Table 6. That is, the bread dough which mix | blended the acidic water soluble protein derived from wheat gluten prepared in Examples 1-5 and Comparative Example 4 was prepared, and the extensibility and the softness of the bread inner phase after baking were evaluated.

  In addition, a bread making test similar to the above was carried out using a gliadin fraction prepared using an acidic ethanol aqueous solution containing citric acid described in Japanese Patent No. 2945279 (Comparative Example 5).

  The method for preparing the gliadin fraction is as follows. That is, 30 g of commercially available powdered gluten (protein 75 wt% (dry matter equivalent), moisture 6 wt%) was added to an acidic ethanol aqueous solution in which 0.6 g of citric acid was dissolved in 300 ml of a 10 vol% ethanol aqueous solution. After time extraction, separation was performed with a centrifuge, and the resulting supernatant was dried using a spray dryer to obtain 11.7 g of a dry powder of the desired gliadin fraction. This dry powder contained 70% by weight or more of the solid contained in the soluble fraction when fractionated with a 70% by volume ethanol aqueous solution.

  The evaluation of the bread dough extensibility and the softness of the bread inner phase was carried out in 5 stages with Comparative Example 5 as the standard (3.0). The higher the value, the better the bread dough and the softer the bread inner phase.

  As shown in Table 8, the test group in which Examples 1 to 5 were blended was the same as Comparative Example 5 in which the amount of gliadin added to the dough was equivalent to that in Comparative Example 5, In comparison, the extensibility of the bread dough and the softness of the bread inner phase were excellent. The acidic water-soluble proteins of Examples 1 to 5 all contain 0.4 to 1.3% by weight of lactic acid, and the acidic water-soluble protein extracted using lactic acid has the same gliadin concentration. However, it is clear that the extensibility is excellent.

  It is clear that the acidic water-soluble protein of the present invention fractionated using lactic acid brings out the characteristics of gliadin more and offsets the properties of glutenin contained as a contamination, thus making it more excellent in extensibility. It became.

  On the other hand, in Comparative Example 4, the lactic acid concentration in the solid content is lower than the acidic water-soluble protein of the present invention, and in the group where Comparative Example 4 was blended, compared with Comparative Example 5 and Examples 1 to 5, The extensibility of bread dough and the softness of the bread inner phase were inferior.

  When the lactic acid concentration is lower than that of the acidic water-soluble protein of the present invention, it is apparent that the extensibility is insufficient as a property of the acidic water-soluble protein, and the added bread has insufficient softness.

  As described above, since the present invention does not use a flammable solvent, it does not require an explosion-proof device and has high work stability. In addition, no special equipment with shearing force is required for extraction, and no special conditions are required for solid-liquid separation by centrifugation. Soluble in acidic water, which is a fraction mainly composed of gliadin, by a very easy fractionation method The protein could be obtained with good yield. The obtained acidic water-soluble protein was excellent in bread-making properties such as the effect of improving the stretchability of the dough and the softness of the bread inner phase.

Claims (3)

A method for producing acidic water-soluble protein, wherein protein soluble in acidic aqueous solution is extracted from wheat gluten,
The acidic aqueous solution is
Containing 1.5 to 3.0 wt% organic acid based on the weight of the wheat gluten dry matter,
Organic acid is from milk acid and malic acid,
The weight ratio of lactic acid to malic acid is lactic acid / malic acid = 83-18 / 17-82,
Contains no flammable solvents, and
The acidic aqueous solution is used in an amount of 8 to 12 times the weight of the wheat gluten dry matter,
The pH of the acidic aqueous solution in which wheat gluten is dispersed at the time of extraction is 3.7 to 4.3,
A method for producing acidic water-soluble protein.   An acidic water-soluble protein obtained by the method for producing an acidic water-soluble protein according to claim 1.   The acidic water-soluble protein according to claim 2, comprising 1.0 to 3.0% by weight of lactic acid and malic acid, and the weight ratio of lactic acid / malic acid = 83 to 18/17 to 82.