JP2005245290A - Method for producing protein processed food hardly presenting bitter taste/astringent taste in acidic region - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a food raw material protein processed food hardly presenting bitter taste/astringent taste even in acidic region, and a food containing the protein. <P>SOLUTION: This method for producing the protein processed food comprises adding a starch decomposed sugar to a protein selected from the group consisting of unheated or heated cow milk serum protein, cow milk casein, soybean protein and albumen protein, and heat-treating the product. The decomposition degree of the starch decomposited sugar to be used is preferably DE 3-40. The solid weight ratio of used quantities of the protein and the starch decomposed sugar is preferably about (1:1)-(1:20). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a food material processed protein product that hardly exhibits astringency and astringency even in an acidic region, and a method for producing a protein-containing processed food.

  Examples of foods containing high protein concentrations include health supplements, medical foods, functional foods for the elderly, nursing foods, sick foods, and sports nutrition supplemented foods. As the protein material, milk protein, egg protein, soybean protein or the like is used. All of these food material proteins have high functionality such as nutrition and physical properties. The foods containing these proteins are generally many products in the neutral pH range, but generally have many tasteless products with low palatability.

  On the other hand, acidic (low pH) foods such as beverages, wine, jelly desserts, sauces, sauces and dressings, dairy products, confectionery, pickles, soups, jams, fruits and fermented foods are known to have high palatability. ing. Then, it is thought that palatability can be improved by giving a refreshing acidity to the said protein high concentration containing foodstuff.

  However, it is known that food material proteins such as milk whey protein exhibit a strong unpleasant astringency and astringency in the acidic range (Egashira et al., Japan Society for Food Science and Technology 2003). However, it was difficult to prepare processed foods with high protein concentration and high palatability.

  Protein in milk whey generated during the production of cheese, butter and casein was a low-use surplus resource. Whey protein has been mainly used as a food material for processed foods with the progress of separation and purification technology. However, whey protein food materials have difficulties in transparency, heat gel formation under high salt concentration, emulsion stability and digestibility. A modified whey protein (see Patent Documents 1 to 3 and Non-Patent Document 1) in which these difficulties are improved is known. However, all whey proteins have strong astringency and astringency in the acidic region (Egashira, Sano, Yodogawa, Hokuto, Japan Society for Food Science and Technology 2003 Conference). Milk casein, soy protein, and egg white protein also exhibit the same unpleasant taste.

  There are bitterness typified by quinine in the taste similar to astringency. It is known that the bitter taste is a reaction via a receptor present on the tongue epithelial cells. On the other hand, for example, the astringency that is felt when astringent tea is included in the mouth is that polyphenols such as tannin in tea form complexes and aggregates with proteins in saliva (proline rich protein), which are the tongue epithelium. It has been reported that it is a taste stimulus due to precipitation in the lipid bilayer membrane present in the oral epithelium (see Non-Patent Document 2), and bitterness and astringency are known to be due to a completely different mechanism. ing. However, there is still no detailed report on the mechanism of astringency that proteins exhibit in the acidic region.

As a method for improving astringency, sweeteners such as sucralose (see Patent Document 4) and aspartame (see Patent Document 5), chitosans (see Patent Document 6), metal salts or amino acids of mono- or diglycerides / polycarboxylic acid esters A method of adding a masking agent such as a salt (see Patent Document 7) is known. However, a technique for reducing the astringency and astringency of the protein itself in the acidic region has not been invented.
Japanese Patent No. 3065116 Japanese Patent No. 3050483 Japanese Patent Publication No. 6-101986 Japanese Patent Laid-Open No. 10-262601 JP-A-10-248501 JP 2000-229862 A JP-A-8-332051 Japanese Society for Food Science and Technology Volume 44, No. 9, p.599-606 (1997) Haslam & Lilley, Critical Reviews in Food Science and Nutrition, 1988

  If the technology to process such protein materials into those that do not exhibit unpleasant astringency or astringency even in the acidic range, the above health supplements and nursing foods can be made more delicious and easy to eat. It is thought that its application can be expanded. Therefore, an object of the present invention is to provide a processed food material protein product that hardly exhibits astringency and astringency even in an acidic region, and a method for producing a food containing the protein.

The astringent taste defined in the present invention is a strong astringency stimulus or a long-lasting astringency stimulus.
In the present invention, a protein selected from the group consisting of milk whey protein, milk casein, soy protein and egg white protein is heated in the presence of starch-degrading sugar, or these proteins are heated and cooled at pH 7.5 or lower. After that, by heating again in the presence of starch-degrading sugar, it was possible to produce a processed protein product that hardly shows astringency and astringency even in the acidic range. Furthermore, by adding the protein processed product thus obtained as a protein source, it has become possible to produce a protein-containing food that hardly exhibits astringency and astringency even in an acidic region.

  As the milk whey protein, for example, a protein fraction in whey obtained as a by-product in the cheese, butter and casein production process is concentrated and purified by, for example, ultrafiltration or chromatography. In addition, milk whey proteins such as WPC (Whey Protein Concentrate), WPI (Whey Protein Isolate), TMP (Total Milk Protein), MPC (Milk Protein Concentrate) or Coprecipitate (Co precipitate) can also be used. Milk casein is also available in sodium, calcium, potassium or magnesium salts. As soy protein, the protein fraction in defatted soybean is concentrated and purified, and concentrated soy protein, extracted soy protein and soy protein isolate can be used. Egg white protein can be obtained by concentrating and purifying the protein fraction in chicken egg white. The purification degree of any protein is not particularly limited, but an ionic strength of 25 mM or less is desirable.

  As the starch-decomposing sugar, powdered or liquid dextrin, maltodextrin, powdered candy, starch syrup and the like can be used. As the degree of decomposition, DE (Dextrose Equivalent) 3-40 is desirable. In addition, it is desirable that the solid content weight ratio of the protein and starch-decomposing sugar is about 1: 1 to 1:20 as the addition amount, and the content of the starch-decomposing sugar in the protein solution is 10 to 70% by weight, In particular, it is desirable to be 30 to 50% by weight.

  When the milk whey protein is heated in the presence of starch-degrading sugar, the pH at the time of heating is not particularly limited, but is preferably 7 or less, which is easily used in the acidic region. The protein is desirably used as an aqueous solution of 2 to 20% by weight, and the heating temperature may be not lower than the denaturation temperature of the protein to be used, but is preferably 70 to 120 ° C. Although the heating time is not particularly limited, it may usually be about 30 minutes to 120 minutes, and after heating, it may be naturally or forcibly cooled or cooled to room temperature or lower.

  When milk whey protein is heated and cooled at pH 7.5 or lower and then heated again in the presence of starch-degrading sugar, it can be used in any pH range as long as the first heating condition is pH 7.5 or lower. . The protein concentration is desirably 2 to 20% by weight, and the heating temperature is not less than the denaturation temperature of the protein to be used, but is preferably 70 to 120 ° C. The heating time is usually about 30 minutes to 120 minutes. After heating, naturally or forcibly cool or cool below room temperature. Next, the heating conditions after adding the starch-decomposing sugar are preferably pH 7 or less, 70 to 120 ° C., and 30 to 120 minutes. After heating, naturally or forcibly cool or cool below room temperature.

  The protein-containing processed food to which 0.1 to 20% by weight of the protein prepared according to the present invention is added has a very palatable taste without astringent taste or astringent taste peculiar to protein even in an acidic range of pH 5 or lower. Become a good food. For example, protein can be contained in any of a solid food, a jelly-like food, a sol-like food, or a liquid food in a weakly acidic to acidic range. Although it does not specifically limit as solid food, It is confectionery, meat, fishery products, etc. The jelly-like food and the sol-like food are not particularly limited, and include desserts, health supplements, medical foods, functional foods for elderly people, nursing foods, sick foods, and sports nutrition supplemented foods. Examples of liquid foods include palatability drinks, sports drinks, health supplements, medical foods, functional foods for the elderly, nursing foods, and sick foods.

  It has been vaguely known so far that food proteins will exhibit astringency and astringency in the acidic range. However, there was no detailed study on the astringency and astringency in the acidic region of milk whey protein. As described above, the authors have found that milk whey protein exhibits astringency and astringency in the acidic region regardless of whether it is native or denatured by establishing a quantitative system for astringency.

  In the present invention, whey protein, casein, soy protein, and egg white protein can be used as raw materials for processed foods in the acidic range by reducing the strong astringency and astringent taste exhibited in the acidic range. Become. Furthermore, the liquid to gel processed foods using the protein material obtained by the present invention are health supplements, medical foods, functional foods for elderly people, nursing foods, foods for the sick, and the like that are excellent in taste. It can be used for foods with high protein content such as sports nutrition supplements.

Next, although the experiment example which shows the history of development of this invention is shown, this invention is not limited by these.
In this example, milk whey protein (WPI) consists of 95% crude protein (dry base, Kjeldahl method), 3% ash (ashing method), 1% lactose, 1% crude fat (acid decomposition method), 5 moisture % (Normal pressure drying method) was used as a whey protein isolate (trade name: Daiichilacto, manufactured by Daiichi Kasei). This was dissolved in distilled water to a 12% and a protein solution to be tested was dialyzed against final 10 ⁴ volumes of distilled water. After adjusting the pH of the WPI solution to 7.0 or 3.5 with 2 M hydrochloric acid or sodium hydroxide, the protein concentration was adjusted to 5% and heated at 90 ° C. for 30 minutes. The modified whey proteins obtained by heating at pH 7.0 and 3.5 were designated as PWP and aPWP, respectively. Bovine gelatin (derived from bovine skin, Type B, gel strength 225 Bloom) and porcine gelatin (derived from porcine skin, Type A, gel strength 300 Bloom) were purchased from Sigma, and 5% suspension was heated at 60 ° C for 10 minutes. Used by dissolving. Tannic acid was purchased from Wako Pure Chemical Industries.

The pH of the whey protein and gelatin solution was adjusted to 3.5 with 2M hydrochloric acid, and dialyzed against 10 ⁴ volumes of 5 mM phosphate buffer (pH 3.5). The pH of the dialyzed solution was accurately adjusted to 3.5 with 5 mM phosphate buffer, and then diluted to a predetermined protein concentration was used as an astringency evaluation sample.

  The sensory test was carried out by panelists of seven healthy men aged 28 to 37 years. The sensory test was performed immediately after the test subject was thoroughly washed with distilled water for each test. After the test, the oral cavity was washed by washing the oral cavity with 150 mM sodium chloride / 10 mM phosphate buffer (pH 7.4). The solvent of the test solution was 2.5 mL of 5 mM phosphate buffer (pH 3.5), and was left at room temperature for at least 2 hours before the test in order to keep the temperature of the test solution constant. Sensory evaluation of astringency by the scoring method used tannic acid as a standard astringency sample.

[Standardization of astringency score]
The astringency score was standardized by the following procedure by comparing the tannic acid solution at an arbitrary concentration with the astringency level of a tannic acid solution at a known concentration with a preset score. 0, 0.343, 0.537, 0.842 and 1.319 mM tannic acid with astringency scores of 0, 2, 4, 6 and 8 respectively, 0.343, 0.429, 0.537, 0.673, 0.842, 1.054, 1.319, 1.651 and The results of evaluating astringency using a 2.066 mM tannic acid solution as an evaluation sample were plotted on a graph (FIG. 1) to create a calibration curve, and the following equation was obtained.
. Astringency score = 4.49985 Ln tannic acid concentration (mM) + 6.32211
From this calibration curve, the astringency scores of 0, 0.383, 0.597, 0.931, 1.452 and 2.264 mM tannic acid were set to 0, 2, 4, 6, 8 and 10. Evaluation of astringency by the scoring method was performed using these as astringency standard samples. The relationship between the astringency score and the sensory evaluation is that 0 is no astringency, 2 is slightly astringent, 4 is slightly astringent, 6 is clearly astringent, 8- 10 means a strong astringency and astringency.

"Measurement of astringency score of astringency evaluation sample using scoring method"
As a result of measuring the astringency score of WPI, PWP and aPWP at pH 3.5, protein concentration of 0.25, 0.5 and 1%, WPI, PWP and aPWP are all 8 to 1 at protein concentration of 1%. It exhibited a strong astringency and astringency corresponding to an astringency score of 9. The intensity of astringency increased depending on the increase in protein concentration, but no difference in intensity was observed between samples.

  On the other hand, as a result of similarly evaluating the strength of astringency for beef and pork gelatin, the astringency score was 1-2, and a clear astringency was not exhibited. In addition, no increase in astringency depending on the protein concentration was observed, and gelatin did not exhibit a clear astringency at pH 3.5. In addition, similar tests were conducted on casein (reagent purified from Nacalai Tesque (derived from milk) by isoelectric precipitation) and soy protein isolate (separated from defatted soybean powder by isoelectric precipitation). It was confirmed that astringency and astringency similar to those of WPI and PWP were exhibited. A part of the data is shown in FIG.

  From the above test, it was confirmed that the degree of astringency can be quantified using the astringency score by a scoring method using tannic acid as an index. Furthermore, it became clear that whey protein exhibits astringency in the acidic range regardless of whether it is undenatured or denatured.

  The isoelectric point of proteins such as milk whey protein is generally around pH 5. For example, whey protein adjusted to pH 3 exhibits astringency and astringency regardless of unheated / heated. The present inventors have found that the taste stimulation is caused by the fact that the aggregate formed when the pH of the protein solution is increased by saliva in the vicinity of neutrality and passes through the isoelectric point region is the epithelium of the tongue or oral cavity. It was thought to be expressed by precipitation in the lipid bilayer membrane present in Therefore, various experiments and studies were conducted on the assumption that adding a large amount of saccharide to a protein can inhibit the protein portion from directly contacting the lipid bilayer membrane in the acidic region. As a result, it was possible to overcome the problem by heating milk whey protein and the like in the presence of starch-degrading sugar. The protein-starch decomposing sugar reaction product according to the present invention does not use a chemical synthesis reaction or an enzyme treatment, and uses only a heat treatment, so there is no problem in using it as a food instead of a synthetic product.

Examples of the present invention will be described below. In Examples, “%” means “% by weight” unless otherwise specified.
[Example 1]
As milk whey protein (WPI), crude protein 95% (dry base, Kjeldahl method), ash content 3% (ashing method), lactose 1%, crude fat 1% (acid decomposition method), moisture 5% (normal pressure) Whey protein isolate (trade name: Daiichilacto, manufactured by Daiichi Kasei Co., Ltd.) as a component, and DE (dextrose equivalent) 3-5,8,19,33 and 40 as starch-degrading sugar The following experiment was carried out using maltodextrin.
WPI, which has been sufficiently dialyzed against water, is prepared as an aqueous solution of pH 7 with a protein content of 5% and starch-degrading sugar concentrations (powder equivalent) of 10, 20, 30, 50, and 70%. After that, heating was performed at 90 ° C. for 120 minutes in a sealed system, and the mixture was sufficiently cooled to room temperature. By this operation, a transparent to translucent viscous protein solution was obtained. By adding sodium chloride to the protein solution and heating, a transparent to cloudy sol-gel was obtained.
Subsequently, the pH of each sample solution was adjusted to 3.5 using 2M hydrochloric acid, and then diluted to a protein concentration of 1% using a phosphate buffer solution of 5 mM, pH 3.5 to obtain a sample for sensory test. This sample was subjected to a sensory test (28 to 37 years old, 7 males) using the above-described scoring method using tannic acid as an index, and the intensity of astringency was measured as an astringency score.
The result is shown in FIG.

  The astringency score at pH 3.5 of WPI heated without adding starch-degrading sugar was 10 and exhibited extremely strong astringency and astringency (starch-degrading sugar concentration 0%, point on Y axis). In the case where DE19 starch-decomposing sugar was added and heat-treated (■), the astringency score was clearly reduced depending on the amount of starch-decomposing sugar added. The same results were obtained with DE 3 to 5 (●), 8 (♦), 33 (◯) and 40 (□).

Normally, the DE value of starch degrading sugar is used as an approximate index of the rate of starch degradation, but in the narrow sense it is also an index of sweetness. It is conceivable that strong sweetness slightly masks the astringency, but the starch-degrading sugar of DE19 or lower used in this test hardly feels sweetness even if the raw powder is directly consumed, and those of DE33 and 40 The sweetness was clearly lower than that of sugar and glucose at the same concentration. In addition, in the preliminary test, the WPI pH 3.5 aqueous solution heated without adding starch-degrading sugar was added with sugar or glucose, but the astringency immediately after being included in the mouth was slightly reduced. (Covering effect due to sweetness), the intensity of astringency recovered with a decrease in sweetness stimulation over time. This indicates that the sweetness of monosaccharides and disaccharides alone has an effect of reducing astringency only while sweetness stimulation is in the mouth, and this effect is temporary. Compared to this, it was confirmed that the whey protein in which starch-decomposing sugars of DE3 to 40 were added and subjected to heat treatment had reduced astringency in the acidic region.
In addition, WPI heated in the presence of starch-degrading sugars of DE 3 to 40 in a pH of 7 and substantially in a salt-free state has transparency, viscosity and gelation characteristics that cannot be obtained with the original whey protein. Thus, it was confirmed that the astringent taste and astringent taste in the acidic range were remarkably lowered. The whey protein prepared by this method can be used for foods such as beverages and jellies.

[Example 2]
Using WPI and DE19 starch-decomposing sugar shown in Example 1 and preparing an aqueous solution with a protein content of 5%, starch-decomposing sugar concentration (powder equivalent) of 50%, and pH 7, the solution was sealed at 90 ° C. at 30, 60, Heating was performed for 90 and 120 minutes. After sufficiently allowing to cool to room temperature, the pH of each sample solution was adjusted to 3.5 using 2M hydrochloric acid, diluted to a protein concentration of 1% using a 5 mM pH 3.5 phosphate buffer, A test sample was obtained. The astringency score of this sample was measured using the same method as in Example 1.
The results are shown in FIG.
WPI heated at 90 ° C. for 30 minutes without adding starch-degrading sugar had a astringency score of 9 at pH 3.5, and showed a very strong astringency and astringency (○), but starch degradation of DE19 In the case where 50% sugar was added and heat-treated at 90 ° C. (●), the astringency score was 4 after 30 minutes, and the astringency was significantly reduced. The astringency score when the heating time was 30 to 120 minutes was 4 to 5, and there was no difference in the astringency reduction effect at any heating time.

[Example 3]
As experimental materials, WPI and DE3-5, 8, 19, 33 and 40 starch-decomposing sugars shown in Example 1 were used. WPI, which has been sufficiently dialyzed against water, is heated at 90 ° C. for 30 minutes in a protein content of 5 to 10%, pH 7, and substantially salt-free. Protein (PWP) was prepared. It is known that the modified whey protein that has been heat-treated in a substantially salt-free state at pH 4 or lower or 6 or higher has excellent properties such as transparency and physical properties that are not found in the original whey protein. (See Patent Documents 1 to 3 and Non-Patent Document 1). After preparing aqueous solutions of modified whey protein concentration 5%, starch-degrading sugar concentration (powder equivalent) 10, 20, 30, 50 and 70%, pH 7, heat again at 90 ° C for 120 minutes in a sealed system And allowed to cool to room temperature. By this operation, a transparent to translucent viscous protein solution was obtained. By adding sodium chloride (25 to 300 mM) to the protein solution and heating, a transparent to cloudy sol-gel was obtained.
The pH of each sample solution was adjusted to 3.5 using 2M hydrochloric acid, and then diluted to a protein concentration of 1% using a phosphate buffer solution of 5 mM and pH 3.5 to obtain a sample for sensory test.
The astringency score of this sample was measured using the same method as in Example 1.
The results are shown in FIG.

  The astringency score at pH 3.5 of PWP heated without adding starch-degrading sugar was 10 (starch-degrading sugar concentration 0%, point on the Y-axis) and exhibited extremely strong astringency and astringency. On the other hand, in the case where DE19 starch-decomposing sugar was added and heat-treated (■), the astringency score was clearly reduced depending on the amount of starch-decomposing sugar added. The same results were obtained with the addition of starch-decomposing sugars of DE 3 to 5 (●), 8 (♦), 33 (◯) and 40 (□).

  A starch solution obtained by adding starch-degrading sugars of DE 3 to 40 to PWP and performing the heat treatment was transparent in the protein solution (modified whey protein) before the starch-degrading sugar was added and re-heating treatment was performed. It was confirmed that the astringency and astringency in the acidic range were significantly reduced while maintaining the properties, viscosity, and gelation characteristics. The whey protein prepared by this method can be used for foods such as beverages and jellies.

[Example 4]
Whether or not the astringency reduction effect of WPI heated in the presence of starch-decomposing sugar shown in Example 1 is due to excess (free) starch-decomposing sugar present in the test solution used during the sensory test Study was carried out.
Using the same method as in Examples 1 and 2, a whey protein solution was prepared by adding starch-degrading sugar of DE8 and subjecting it to heat treatment. The protein content was 5%, the amount of starch-degrading sugar added was 50%, and the heat treatment was 90 ° C. for 30 minutes. Next, excess (free) starch-degrading sugar in the test solution was removed by ultrafiltration with a molecular weight cut off of 300,000 Da (UF method). The pH of the test solution was adjusted to 7, diluted with 4 volumes of distilled water, and then subjected to UF treatment until the same volume as the original test solution. This UF treatment was repeated 6 times, and the amount of starch-decomposing sugar remaining in the test solution was measured each time using the phenol-sulfuric acid method. Excess starch-degrading sugar remaining in the sample solution became 20% or less before the treatment after the first UF treatment, and became almost 0 after the third treatment.
FIG. 6 shows the results of measuring the astringency score of the test solution obtained by repeating UF treatment 6 times using the same method as in Examples 1 and 2. As controls, WPI, a mixture of WPI and starch-decomposing sugar, and a heat-treated product of WPI and starch-decomposing sugar were used.

  The astringency score at pH 3.5 of WPI slightly decreased by adding starch-degrading sugar, but the astringency score greatly decreased by heat treatment. On the other hand, it was confirmed that the astringency score was significantly low even in the test solution from which excess starch-degrading sugar was completely removed. From these results, the whey protein was heat-treated in the presence of starch-degrading sugar, and a complex of protein and starch-degrading sugar was formed, so lipids present in the tongue epithelium and oral epithelium in the acidic region. It was considered that the astringency was reduced by the direct deposition of the protein portion on the bilayer membrane being alleviated. Further, it was confirmed that the astringency reduction effect by the starch-decomposing sugar itself remaining in the test solution was very slight.

[Example 5]
Using the same method as in Example 3, the same test as in Example 4 was carried out using the whey protein solution obtained by adding starch-degrading sugar of DE8 to PWP and again heat-treated. Shown in The protein content was 5%, the amount of starch-degrading sugar added was 50%, pH 7, and the heat treatment was 90 ° C. for 30 minutes.
The astringency score of PWP at pH 3.5 was slightly reduced by adding starch degrading sugar, but the astringency score was greatly reduced by adding starch degrading sugar and heating again. On the other hand, it was confirmed that the astringency score was significantly low even in the test solution from which excess starch-degrading sugar was completely removed. From these results, the effect of reducing astringency is due to the formation of a complex of protein and starch-degrading sugar by heat treatment of PWP in the presence of starch-degrading sugar. It was suggested that the direct precipitation of the protein portion into the lipid bilayer membrane existing in the epithelium was obtained by relaxation. Further, it was confirmed that the astringency reduction effect by the starch-decomposing sugar itself remaining in the test solution was very slight.

[Example 6]
Casein (Nacalai Tesque reagent casein (derived from milk) repurified by isoelectric precipitation), soy protein isolate (separated from defatted soybean powder by isoelectric precipitation), dried egg white Powdered starch (manufactured by Daiichi Kasei) and starch starch of DE8 were used. Using the method shown in Example 1, each protein was heat-treated in the presence of starch-degrading sugar. The protein content was 3%, the amount of starch-degrading sugar added was 50%, pH 7, and the heat treatment was 90 ° C. for 30 minutes.
The astringency score of each protein solution after the heat treatment was measured using the method shown in Example 1. The results are shown in FIG.
From the test results, it was confirmed that casein, soy protein, and egg white protein exhibited strong astringency in the acidic range, but the astringency decreased by heat treatment in the presence of starch-decomposing sugar.

[Example 7]
As experimental materials, the starch-decomposing sugars of WPI, PWP and DE8 shown in Examples 1 and 3 were used. A sample protein solution was prepared using the methods shown in Examples 1 and 3. The protein content was 5%, the amount of starch-degrading sugar added was 50%, pH 7, and the heat treatment was 90 ° C. for 30 minutes. The obtained protein solution was freeze-dried (Neocool manufactured by Yamato). Both samples after lyophilization were dissolved in distilled water, adjusted to pH 3.5 with 2M hydrochloric acid, diluted to 1% protein concentration with 5 mM, pH 3.5 phosphate buffer, for sensory testing. A sample was used. The astringency score of this sample was measured using the same method as in Example 1. The results are shown in FIG.
It was confirmed that the astringent taste reducing effect of both whey proteins prepared and freeze-dried by the method shown in Examples 1 and 3 was not impaired by freeze-drying. From this, it was confirmed that the whey protein obtained by the present invention can be easily handled as a food material for processed foods.

[Example 8]
Sample protein solutions were prepared using the methods of Examples 1 and 3 using the WPI, PWP and DE8 starch-decomposing sugars shown in Examples 1 and 3. The protein content was 5%, the amount of starch-degrading sugar added was 50%, pH 7, and the heat treatment was 90 ° C. for 30 minutes. The obtained sample protein solution was concentrated to a protein concentration of 6.4% using the UF method, and then adjusted to pH 3.5 using 1M phosphoric acid.
Sample protein solution (protein concentration 6.4%, pH 3.5) 78.5%, sugar mixed isomerized sugar 12%, vitamin B ₂ 0.05%, lemon flavor 0.05% and drinking water 9.4% An acidic protein beverage was prepared using the recipe.
As a trial production procedure, (1) vitamin B ₂ is dissolved in drinking water, (2) the sample protein of Example 1 or 3 and, as a control, a starch-decomposed sugar-free product and a sugar mixed isomerized sugar are added and mixed. (3) A fragrance was added, (4) after filling the container, heating at 90 ° C. for 20 minutes, and (5) quenching. By these operations, a transparent and slightly viscous beverage could be prepared. The pH of the beverage was 3.5 and the protein content was 5%.
The astringency score was measured for the obtained acidic protein beverage using the method shown in Example 1. The results are shown in FIG.

  Acidic protein beverages using WPI and PWP that have not undergone the astringency reduction treatment exhibited extremely strong astringency and astringency. On the other hand, the astringency of beverages using WPI and PWP that have been heat-treated in the presence of starch-degrading sugar has been significantly reduced, and the degree of astringency is not significantly different from that of commercially available non-protein taste drinks. It was. From this result, it was confirmed that a beverage containing 5% of a protein having a refreshing acidity and not exhibiting astringency and astringency can be prepared according to the present invention.

[Example 9]
Using the WPI and DE8 starch-decomposing sugars shown in Example 1, sample protein solutions were prepared using the methods of Examples 1 and 3. The protein content was 5%, the amount of starch-degrading sugar added was 50%, pH 7, and the heat treatment was 90 ° C. for 30 minutes. The obtained sample protein solution was concentrated to a protein concentration of 10.8% using the UF method, and then adjusted to pH 3.5 using 1M hydrochloric acid.
Sample protein solution (protein concentration 10.8%, pH 3.5) 89.9%, aspartame preparation 5%, 5% calcium lactate aqueous solution 5%, vitamin B ₂ 0.05%, and lemon flavor 0.05% recipe Was used to prepare acidic protein jelly.
The trial procedure, (1) dissolving the aspartame preparation and vitamin B ₂ in water, (2) the sample protein of Example 1 or 3 and, as control, added to and mixed with starch degrading sugar additive-free products, (3) A fragrance was added, (4) after filling the container, heating at 90 ° C. for 40 minutes, and (5) quenching. By these operations, a transparent jelly could be prepared using PWP without addition of starch-decomposing sugar and Examples 1 and 3. However, WPI without addition of starch-decomposing sugar did not form a jelly but became cloudy.

  The astringency score was measured using the method shown in Example 1 for the obtained acidic protein jelly and cloudy precipitate. As a result, the cloudy precipitation and jelly using WPI and PWP, which had not been subjected to astringency reduction treatment, exhibited extremely strong astringency and astringency, but WPI that had been heat-treated in the presence of starch-decomposing sugars The astringency of jelly using PWP and PWP was significantly reduced, and the degree of astringency was not significantly different from that of commercially available dessert jelly. From this result, it was confirmed that a high protein jelly having a refreshing acidity and no astringency or astringency can be prepared according to the present invention.

FIG. 1 is a graph showing a calibration curve created by a scoring method using tannic acid as a reference for astringency and astringency. FIG. 2 is a graph showing the protein astringency score in the acidic region using the scoring method. FIG. 3 is a graph showing the astringency score of WPI heat-treated by adding 10-70% starch-degrading sugar of DE 3-40. It is a graph which shows the astringency score of WPI which added the starch decomposition sugar of DE19 50%, and heat-processed at 90 degreeC for 30 to 120 minutes. It is a graph which shows the astringency score when PWP is reheat-processed in the presence of starch-decomposing sugar. It is a graph which shows the astringency score when the excess starch decomposing | disassembling sugar in the whey protein liquid prepared from WPI by an example of this invention is removed. It is a graph which shows the astringency score when the excess starch decomposing | disassembling sugar in the whey protein liquid prepared from PWP by an example of this invention is removed. It is a graph which shows the astringency score in the acidic region of the food protein heated in the presence of starch decomposition sugar. It is a graph which shows the astringency score of the heat-processed whey protein in the presence of the starch decomposition sugar which performed freeze-drying (FD). It is a graph which shows the astringency score of the acidic protein drink which added the heat processing whey protein in the presence of starch decomposition sugar.

Claims (5)

Produces a protein processed product that does not exhibit astringency or astringency even in acidic regions by heating a protein selected from the group consisting of milk whey protein, milk casein, soy protein and egg white protein in the presence of starch-degrading sugar. how to. A protein selected from the group consisting of milk whey protein, milk casein, soy protein and egg white protein is heated and cooled at pH 7.5 or lower, and then heated again in the presence of starch-decomposing sugar, so that it is astringent even in the acidic range. -A method for producing processed protein products that do not exhibit astringent taste. The method of claim 1 or 2, wherein the protein is milk whey protein. The method according to any one of claims 1 to 3, wherein the protein and starch-decomposing sugar are used in a weight ratio of 1: 1 to 1:20 in terms of solid content. A protein-containing processed food that is less likely to exhibit astringency or astringency even in an acidic region, wherein the protein processed product obtained by any one of claims 1 to 4 is added.

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