JP2018148851A - Rice flour for bread, mixed flour for bread, bread, and manufacturing method of bread - Google Patents

Abstract

The present invention provides bread rice flour, bread brown rice flour, bread flour containing the rice flour or brown rice flour, and bread, which enable the production of bread having a large volume and softness. An apparent content of amylose in a range of 15% by mass to 30% by mass, a super long chain in a range of 2.5% by mass to 5.0% by mass, and a long length The above problem is solved by rice flour containing amylopectin in which the ratio (S / T) of the mass% (T) of the chain and the mass% (S) of the short chain is in the range of 2.5 or more and 4 or less. Bread mixed flour contains such bread rice flour, and bread is produced using bread rice flour or bread mixed flour. [Selection] Figure 1

Description

  The present invention relates to bread flour containing brown rice flour, mixed flour for bread containing the rice flour, bread produced using the rice flour or mixed flour, and a method for producing bread.

  In recent years, various efforts have been made to expand rice consumption as part of improving food self-sufficiency. One of these efforts is the expansion of the use of rice flour. In addition to conventional rice flour used for Japanese confectionery such as rice cakes and dumplings, use in new fields such as bread and confectionery has been developed (see Patent Documents 1 and 2). ).

  However, the bread manufactured with rice flour has a problem that it has a small volume and tends to be harder than a conventional bread manufactured with wheat flour. For example, in Patent Document 1, the volume and softness of rice flour bread are examined only by the amylose content. According to this study, high amylose rice such as “Koshi no Kaori” and “Momiroman” with amylose content of 23% or more from ordinary varieties such as “Akitakomachi” and “Koshihikari” with amylose content of 18% to 22% are used. By doing so, it is said that a rice flour bread having a crisp texture and an excellent volume can be obtained. Non-Patent Document 1 reports that there is a high correlation between the content of amylose and the specific volume of bread, and the amylose content at which the specific volume reaches its maximum (peak) is estimated to be around 25%. Yes.

JP2013-085513A JP 2009-232800 A

Makoto Takahashi, Noriyuki Honma, Keiko Morohashi, Koichi Nakamura, Yasuhiro Suzuki, Japan Society for Food Science and Technology, Vol. 56, No. 7, pp. 394-402 (2009).

  However, in the current technology including the technology described in Patent Document 1 and the like, the volume increases as the amylose content increases, but it tends to become harder and appropriately meets the market needs that expect softness. I could not say. Patent Document 2 also describes “amylopectin”, but neither describes nor suggests the structure of amylopectin that can meet the above expectation. Non-Patent Document 1 reports that the specific volume of bread has a high correlation with the amylose content, but does not mention amylopectin.

  The present invention has been made in order to solve the above-mentioned problems, and the object thereof is to make a bread having a large volume and softness, and making this bread flour containing brown rice flour, An object of the present invention is to provide a bread-containing mixed powder, a bread manufactured using the rice flour or the mixed powder, and a method for manufacturing the bread.

  According to the inventor's research, it was recognized that there was a difference in the volume and softness of the bread produced despite the similar amylose content in rice flour between different varieties. In other words, we found that the volume and softness of bread made from rice flour was not due to the amylose content alone, and based on this, we determined that the structure (chain structure) of amylopectin also affected. In addition, the present invention has been completed.

  (1) The bread rice flour according to the present invention has an apparent content of 15% by mass or more and 30% by mass or less of amylose and an ultralong chain of 2.5% by mass or more and 5.0% by mass or less. And amylopectin in which the ratio (S / T) of the mass% (T) of the long chain and the mass% (S) of the short chain is within the range of 2.5 or more and 4 or less. It is characterized by.

  (2) The bread flour according to the present invention includes the rice flour according to the present invention.

  (3) The bread according to the present invention is characterized by being produced using the bread rice flour according to the present invention or the bread mixed flour according to the present invention.

  (4) The bread manufacturing method according to the present invention has an apparent content of 15% by mass or more and 30% by mass or less of amylose and ultralong chains of 2.5% by mass or more and 5.0% by mass or less. And amylopectin containing a long chain mass% (T) and a short chain mass% (S) ratio (S / T) of 2.5 or more and 4 or less A step of selecting a rice flour for bread, a step of preparing a mixed powder for bread containing the selected rice flour for bread, and a step of obtaining a rice flour bread with the prepared mixed powder for bread To do.

  According to the present invention, even bread using rice flour can be obtained with a large volume and yet softness (less crumbly). Moreover, according to this invention, the rice flour and mixed flour for manufacturing this bread can be provided.

It is a photograph of the bread manufactured using sample rice flour B, D, and E in Experiment 2. It is a figure which shows the chain length distribution of the rice flour used in Experiment 1 and Experiment 2. It is a figure which shows chain length distribution of the amylopectin contained in the rice flour used in Experiment 1 and Experiment 2.

  The bread rice flour, bread mixed flour and bread, and bread manufacturing method according to the present invention will be described in detail. In addition, this invention is not limited only to the following embodiment and an Example, The range including the summary is included.

[Bread rice flour]
The rice flour for bread according to the present invention has an apparent content of 15% by mass or more and 30% by mass or less of amylose and ultralong chains of 2.5% by mass or more and 5.0% by mass or less. And amylopectin in which the ratio (S / T) of the mass% (T) of the long chain and the mass% (S) of the short chain is in the range of 2.5 or more and 4 or less. By making bread with such rice flour for bread, even bread using rice flour can be obtained with a large volume and yet soft (low-paste) bread.

  The present inventor made rice flour from several varieties, paying attention to the apparent amylose content and the structure (chain structure) of amylopectin contained in the rice flour, and the volume and softness of bread are contained in rice flour. It was found that not only the apparent amylose content but also the chain structure of amylopectin had a great influence. By identifying them, we were able to make bread that realized both volume and softness.

  Hereinafter, each component of the present invention will be described.

(rice flour)
Rice flour is flour used as a raw material for bread and can be obtained by milling rice. Rice includes brown rice. In addition, the brown rice flour which milled brown rice contains the rice bran component in addition to the component of rice flour, and the ratio of such rice bran component is generally contained about 10 mass% in the brown rice flour. In addition, as a method for obtaining rice flour, a known milling method or a pulverizer can be used. Examples of the pulverizer include a high-speed rotational impact pulverizer, an airflow pulverizer, and a cylinder-type pulverizer. it can.

  As for the applicable rice varieties, various varieties of rice can be applied as long as the conditions such as mass ratio described later are satisfied. Examples of varieties satisfying such conditions include, for example, Tsukushi Homare and Mizuhochikara evaluated in Experiment 1 and Experiment 2 described later, or other varieties having similar effects.

(Amylose)
Amylose is a polymer in which a number of α-glucose molecules are polymerized by glycosidic bonds to form a straight chain. In the present invention, amylose is contained in the rice flour within an apparent content of 15% by mass to 30% by mass. When the apparent content of amylose was less than 15% by mass, the volume feeling of the finally obtained bread tended to be remarkably reduced. When the apparent content of amylose exceeds 30% by mass, the bread finally obtained lacks softness and is hard and tends to be noticeable. In addition, mass% means the mass ratio in the starch contained in rice flour.

  The “apparent content” refers to an amount detected as equivalent to amylose when components of rice flour are analyzed by HPLC (liquid high performance chromatography) described later. That is, the molecular structure of amylose is long and linear, and has a structure close to that of amylopectin, which will be described later. During analysis, this amylopectin ultralong chain is also detected as amylose. Here, the amylose content detected in a form including an ultralong chain of amylopectin is defined as “apparent content”. In order to calculate the actual amylose content, the amylopectin content is separately analyzed, and then the analyzed amylopectin content is subtracted from the “apparent content”.

  In the present invention, the apparent content of amylose contained in rice flour is specified, but the apparent content of amylose may be specified based on the starch in the rice flour. That is, since about 80% of rice flour is starch, for example, when starch occupies 80% of rice flour, the apparent amylose content in starch is within the range of 12% by mass or more and 24% by mass or less. Can do. In addition, when brown rice flour is used as the rice flour, the apparent content of amylose can be specified based on the brown rice flour. In that case, since the ratio of the rice bran component in the brown rice flour is about 10% by mass, it can be said that “the apparent amylose content in the brown rice flour is in the range of 13.5% by mass to 27% by mass”.

(Amylopectin)
Amylopectin is a polymer in which a number of α-glucose molecules are polymerized by glycosidic bonds, but unlike amylose, it has a highly branched structure. Amylopectin is a polymer having a chain structure in which unit chains such as a short chain, a long chain, and an ultralong chain are linked by this branching method.

  The “short chain” of amylopectin is a short unit chain involved in the formation of one cluster unit among the unit chains constituting the amylopectin molecule. In the measurement of the chain length distribution of debranched starch (or amylopectin), it is a group of unit chains detected as the lowest peak on the lowest molecular side, and the degree of polymerization of the peak is around 10.

  The “long chain” of amylopectin is a long unit chain that participates in the linking of two or three clusters among the unit chains constituting the amylopectin molecule. It is a group of unit chains detected as a peak eluted in the molecular weight region between short chains and ultralong chains in the measurement of chain length distribution of debranched starch (or amylopectin), which is less content than short chains. The degree of polymerization of the peak is around 40.

  The “very long chain” of amylopectin is a unit chain having a very long chain length compared to a short chain and a long chain that occupy most of the unit chains constituting the amylopectin molecule. Unit chain with the degree of polymerization of about 100 or more, which is the smallest content compared to short and long chains, and is detected as the peak eluting on the most polymer side in the measurement of the chain length distribution of debranched starch (or amylopectin) It is.

  In the present invention, rice flour is particularly limited by limiting the mass% of the ultralong chain of amylopectin and the ratio (S / T) of the mass% (T) of the long chain to the mass% (S) of the short chain to a specific range. I found out that even the bread produced in can achieve both large volume and softness. That is, the amylopectin contained in rice flour has an ultralong chain in the range of 2.5% by mass to 5.0% by mass, and the long chain mass% (T) and the short chain mass% (S ) Ratio (S / T) is in the range of 2.5 or more and 4 or less, which is an important parameter.

(Super long chain)
The very long chain of amylopectin is in the range of 2.5% by mass or more and 5.0% by mass or less. If the ultra-long chain is less than 2.5% by mass, it may not be possible to obtain a large volume comparable to bread produced using wheat flour. When the ultra-long chain exceeds 5.0% by mass, the bread volume may be small, the softness may be lacking, and it may be hard and crisp.

(Long and short chain)
The ratio (S / T) of the long chain mass% (T) and the short chain mass% (S) of amylopectin is in the range of 2.5 or more and 4 or less. When the ratio (S / T) of the mass% of the short chain to the mass% of the long chain of the amylopectin is less than 2.5, it may be lacking in softness and hard, and may become harsh. On the other hand, if the mass% ratio (S / T) exceeds 4, it may not be possible to obtain a large volume comparable to bread produced using wheat flour.

  As described above, in the present invention, by specifying the apparent amylose content in rice flour and the structure (chain structure) of amylopectin as described above, the present invention has a large volume comparable to bread using wheat flour. However, the trade-off between eliminating the hardness (passy) that becomes a defect in bread using rice flour is achieved at a high level.

  The starch damage degree and the average particle diameter of rice flour are not particularly limited, but the starch damage degree is preferably 5% or less, and the average particle diameter is preferably about 5 μm or more and 100 μm or less. By setting the starch damage degree and the average particle diameter within such ranges, the volume and softness of bread using rice flour can be made more preferable.

[Bread mixed flour]
The bread flour according to the present invention contains the above-mentioned bread rice flour. In addition to the bread rice flour described above, a known substance added to the bread mix flour may be included in a known ratio. For example, bread yeast such as sugar, salt, fats and oils, yeast, gluten, starch, swelling agent, thickening polysaccharide, milk powder and the like may be added as appropriate. Moreover, the gluten free mixed powder which does not contain gluten may be sufficient.

[Bread and its production method]
The bread which concerns on this invention is manufactured by a well-known method using said rice flour for bread or mixed flour for bread. The manufacturing method includes a step of selecting bread rice flour, a step of preparing bread mix flour, and a step of obtaining rice flour bread with the prepared bread mix flour.

  The process of selecting the rice flour for bread consists of amylose with an apparent content of 15% by mass or more and 30% by mass or less, and ultralong chains of 2.5% by mass or more and 5.0% by mass from the rice flour. And amylopectin in which the ratio (S / T) of the mass% (T) of the long chain and the mass% (S) of the short chain is in the range of 2.5 or more and 4 or less. This is a process of selecting rice flour as bread rice flour. The rice flour may be known rice flour, or rice flour that is under development or will be developed in the future. Rice flour satisfying the above conditions is selected from these rice flours as bread flour.

  The step of preparing the bread mix powder is a step of adding ingredients such as sugar, salt, fat, yeast and other yeasts to the bread rice flour and mixing with a mixer to prepare the bread mix powder. .

  The step of obtaining rice flour bread is a step of obtaining rice flour bread with the prepared bread flour mixture. Specifically, the bread is added to the bread rice flour with ingredients such as sugar, salt, fats and yeasts, yeast for bread, water, etc., or water is added to the bread flour and mixed with a mixer. It can be obtained by first fermenting using dough or batter-like dough, forming it, and further subjecting it to secondary fermentation, followed by firing. In addition, when bread yeast etc. are contained in bread mix powder, since fermentation progresses only by mixing bread mix powder and water, the bread which concerns on this invention can be manufactured easily. It becomes.

  In addition, since various materials are contained in the prepared bread mix powder and bread batter, rice powder is taken out from the mix powder and batter, the rice flour is analyzed, and the analysis result is the above-mentioned present invention. If the constituent elements of the bread rice flour are satisfied, it can be said that the mixed flour or batter is the mixed flour or batter according to the present invention. On the other hand, bread produced with the mixed flour or batter cannot extract only bread rice flour and contains various material components. Therefore, it is not easy if not impossible to accurately determine whether or not the obtained bread is produced using the bread rice flour having the characteristics of the present invention, Thus, it can be said that there is a circumstance that the obtained bread cannot be directly identified by the characteristic structure or characteristic of the present invention or is not practical.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the above-described embodiment and the following examples, and various modifications can be made without departing from the spirit of the present application.

[Adjustment of sample rice flour]
Sample rice flour A to E consisting of the following five varieties was used for bread production, bread measurement, and structural analysis of amylopectin chain structure. Sample rice flour A is tsukushihomare rice flour (starch damage degree 2.8%, average particle size 46 μm), sample rice flour B is Hoshiyutaka rice flour (starch damage degree 2.7%, average particle size 46 μm), and sample rice flour C is Variety-improved rice flour (variety name undecided, starch damage degree 2.4%, average particle size 43 μm), sample rice flour D is Mizuhochikara rice flour (starch damage degree 2.7%, average particle size 45 μm), sample rice flour E is Hinohikari rice flour (starch damage degree 2.6%, average particle size 44 μm). In addition, the starch damage degree and average particle diameter of the sample rice flour were set to the same level so that the influence of the sample rice flour on the bread volume and softness was reduced. The measuring method of the starch damage degree and average particle diameter of sample rice flour is shown below.

(Measurement method of starch damage)
As a method for measuring the degree of starch damage, Starch Damage Assay Kit (manufactured by Megazyme) was used to measure the degree of starch damage of rice flour. First, 100 mg of rice flour was weighed into a test tube, 1 mL of an α-amylase solution (50 U / mL) was added, and this was reacted in an environment at 40 ° C. for 10 minutes. Next, 8 mL of sulfuric acid solution (0.2% V / V) was added to stop the reaction, and then centrifugation was performed at 3000 rpm for 5 minutes. Then, 0.1 mL of the centrifugal supernatant was collected in a new test tube, and 0.1 mL of an amyloglycosidase solution (2 U / mL) was added thereto, and the mixture was reacted for 10 minutes in a 40 ° C. environment.

  Next, add 4 mL of GOPOD solution (dissolved by adding Bottle 4 attached to Total Starch Assay Kit to 1 L of Bottle 3 attached to Total Starch Assay Kit with water) and react for 20 minutes in an environment of 40 ° C. I let you. Then, the absorbance of the reaction solution was measured at a wavelength of 510 nm. About this measurement result, the starch damage degree was computed using following formula (1) as described in the instruction manual of Starch Damage Assay Kit used for measurement. The blank absorbance was obtained by the same treatment except that 0.1 mL of ultrapure water was used instead of the centrifugal supernatant. Starch damage degree (%) = (absorbance of sample rice flour−absorbance of blank) × (absorbance of 150/150 μg / mL glucose standard solution) × 8.1 (1)

(Measuring method of average particle size)
The average particle size was measured for each sample rice flour with a laser diffraction particle size distribution analyzer (Mastersizer 2000, manufactured by Malvern). As the average particle diameter, D [4, 3] volume average diameter was used.

[Experiment 1]
The above-mentioned sample rice flours A to E were used, respectively, and bread was produced using the respective compounding amounts as sample rice flour 410 g, wheat gluten 90 g, salt 9 g, sugar 40 g, baker's yeast 12.5 g, fats and oils 40 g, and water 400 g.

  First, baker's yeast and water were put into a vertical bread mixer (AM-20, manufactured by Aikosha Seisakusho Co., Ltd.) and stirred with a whipper. Next, after adding sample rice flour, wheat gluten, salt and sugar, mixing was performed at low speed for 3 minutes and then at medium speed for 3 minutes. Finally, fats and oils were put into the mixed material, and mixed again at a low speed for 3 minutes and at a medium speed for 3 to 5 minutes to prepare bread dough. Then, the mixed dough was divided into 250 g portions and subjected to primary fermentation for 20 minutes at room temperature while preventing the dough from drying. This process was performed for each of the sample rice flours A to E.

  Next, using the bread-making machine (OSHIKIRI MQ, manufactured by OSHIKIRI), the dough produced above was shaped into a mountain bread. The molded dough was put in a case and subjected to secondary fermentation for 60 minutes in an environment of a temperature of 38 ° C. and a humidity of 85%. After this fermentation was completed, the oven was baked for 25 minutes in an oven (TOOE STOVEN, manufactured by ToKuRa) at 210 ° C. for both the upper and lower flames, the power set to 2 for the upper flame and 4 for the lower flame. The baked bread was immediately removed from the mold and allowed to cool at room temperature for 3 hours. After cooling, it was stored in a sealed plastic bag. The next day after sealing and storage, the bread volume and softness were measured.

(Measurement method of volume and softness)
The volume was measured with a non-contact laser volume / mass meter (volscan profiler 600, manufactured by Stable Micro Systems). The evaluation of the volume takes into consideration the general volume (about 2000 mL or more) when using flour as a benchmark, ○ (good) if the volume is 1900 mL or more, and Δ if it is less than 1900 mL and 1800 mL or more. (Yes), and x (No) if less than 1800 mL. The volume measurement results are shown in Table 1.

  The softness was measured until 7 days after firing. The softness was measured by cutting the bread into a size of 30 mm and measuring it with a 10 mm compression test with a plunger having a diameter of 36 mm (Texture Analyzer, manufactured by Stable Micro Systems). The evaluation of the measurement result is to measure the load (g) when compressed by 10 mm, and ◎ (excellent) is less than 100 g in a range in which a general person hardly feels a difference in food texture, and ○ ( Good), 150 g or more and less than 200 g was set as Δ (possible), and 200 g or more was marked as x (impossible). Table 1 shows the measurement results of the softness.

  Based on the evaluation of volume and softness, comprehensive evaluation was performed. Comprehensive evaluation was performed in consideration of a normal bread consumption form (about 4 to 5 days after production is often regarded as the expiration date). As a result, it was evaluated that sample rice flour A and sample rice flour D were good. The results of comprehensive evaluation are shown in Table 1.

[Experiment 2]
The above-described sample rice flours B, D, and E were used, and gluten-free breads were prepared with the blending amounts of sample rice flour 100 g, salt 1.5 g, sugar 8 g, baker's yeast 1 g, and water 100 g.

  First, all of the above materials were put into a bowl, and the mixture was sufficiently stirred until the powder disappeared with a whipper to prepare a batter-like dough. Thereafter, 160 g of the dough was put into a 500 mL beaker and fermented with a Helsior AX-MX2 (manufactured by Sharp Corporation) at 40 ° C. until the beaker scale reached 300 mL. After fermentation, it was baked at a temperature of 210 ° C. in an oven (Fine Oven DF62, manufactured by Yamato). Subsequently, it evaluated after standing to cool for 1 hour. The volume was measured with the same non-contact type laser volume / mass meter as in Experiment 1. The evaluation of the volume was performed by visual evaluation based on sensory experience values, and those having a volume feeling were evaluated as “good” and those having no volume were determined as “no”. Also, the softness and fineness of the texture were evaluated by visual and palpation evaluation based on sensory experience values. The softness and fineness of the texture were evaluated as ◯ (good), and the softness and texture were determined as x (impossible). Moreover, the photograph of the bread | pan manufactured using each sample rice flour is shown in FIG. These results are shown in Table 2.

  A comprehensive evaluation was performed based on the evaluation of volume and softness / fineness of texture. The results of comprehensive evaluation are shown in Table 2. Also for gluten-free bread, good results were obtained when using rice flour (sample rice flour D) that satisfies the components of the present invention.

[Measurement method of starch unit chain length distribution and apparent amylose content]
The apparent content of amylose and the measurement of the unit chain length distribution of starch will be described. In these measurements, 5 mg of sample rice flour was suspended in 300 μL of 90% dimethyl sulfoxide, and sufficiently heated and dissolved in a boiling bath. An equal amount of ethanol was added thereto, cooled in ice for 2 hours, and centrifuged (model 2700, 3000 rpm, 4 ° C., 10 minutes) manufactured by Kubota Corporation to collect the resulting precipitate. This operation was repeated again to degrease the sample rice flour. After adding 1240 μL of ultrapure water to the defatted sample rice flour and dissolving it by heating in a boiling bath, an acetate buffer was added to a final concentration of 10 mM, and the pH was adjusted to 3.5. Pseudomonas isoamylase was added to this so that it might become a 0.03U / mg substrate, and it was made to react under the temperature environment of 45 degreeC for 16 hours. And after heating in a boiling bath and stopping reaction, it was made to dry with a centrifugal evaporator.

  Fluorescent labeling of the debranched sample was performed according to a previous report (Hanashiro et al., Carbohydr. Res., 337 (2002), p. 1211-1215). Then, 55.5 μL of 90% dimethyl sulfoxide was added to the dried sample and heated in a boiling bath, and then 44.5 μL of ultrapure water was added and further heated to completely dissolve the sample rice flour. To the dissolved sample solution was added 100 μL of 2-aminopyridine solution (1 g dissolved in 760 μL of concentrated hydrochloric acid), and the mixture was kept at 60 ° C. for 1 hour in the dark, and then sodium cyanoborohydride solution (52.9 mg). Was dissolved in 100 μL of ultrapure water) and 100 μL was added and kept under the same conditions for 24 hours to fluorescently label the reducing end groups.

  Then, 300 μL of 83% dimethyl sulfoxide was added to the fluorescently labeled sample and filtered (pore size 0.22 μm), and 30 μL of this filtrate was subjected to size exclusion chromatography. Here, the configuration of this chromatograph set is as follows. Connect a total of four columns (two from Shodex OHpak SB-G, OHpak SB-803 HQ, and OHpak SB-802.5 HQ, two columns) to a general-purpose degasser and a general-purpose HPLC pump in this order at 50 ° C. Holding) and connecting the column eluate to a fluorescence detector (manufactured by JASCO Corporation, FP-2020 Plus, excitation wavelength 315 nm, measurement wavelength 400 nm), differential refractometer (manufactured by JASCO Corporation, RI-2031 Plus). The detector outputs were sequentially introduced, and these detector outputs were collected by a chromatographic data processing apparatus (Jasco-Borwin, manufactured by JASCO Corporation) to obtain a chromatogram.

  The chromatogram was fractionated into three fractions of apparent amylose, short chain, and long chain in the order of peak elution. At this time, the apparent amylose fraction elution end position is the inflection point of the peak valley in the chromatogram by the refractometer output, and the elution end position of the long chain fraction is the peak valley in the chromatogram by the fluorometer output. Inflection points. The ratio of each of these three fractions to the entire elution peak was expressed as a percentage. The percentage value of the apparent amylose fraction determined for the refractometer chromatogram was taken as the apparent amylose content. FIG. 2 is a diagram showing the chain length distribution of rice flour used in Experiment 1 and Experiment 2.

[Measurement of unit chain length distribution and ultralong chain content of amylopectin]
Preparation of amylopectin from sample rice flour was performed according to the previous report (Takeda et al., Carbohydr. Res., 148 (1986) 299-308). Amylopectin debranching and fluorescent labeling, and size exclusion chromatography of labeled samples were performed as described above. This was carried out in the same manner as in the case where the starch was used as a sample. However, in the case of amylopectin, the fraction obtained as an apparent amylose fraction when starch was used as the sample was the ultralong chain fraction (Hanashiro et al., Plant Cell Physiol., 49 (2008), p. 925-933). The percentage value of the ultralong chain (ELC) fraction determined for the refractometer chromatogram was taken as the ultralong chain (ELC) content. FIG. 3 is a diagram showing the chain length distribution of amylopectin contained in the rice flour used in Experiment 1 and Experiment 2.

  Table 3 shows the apparent amylose content, the ultralong chain content in amylopectin, and the ratio of long and short chains obtained as described above.

  From the above, preferable results were obtained with the sample rice flours A and D. From the amylose content of the sample rice flours A and D and the ratio of the super long chain and short chain to long chain of amylopectin, the apparent content range of amylose is 15.9 mass% or more and 20.5 mass% or less. The range of the ultralong chain is 2.6 mass% or more and 3.6 mass% or less, and the ratio of the mass% (S) of the short chain to the mass% (T) of the long chain of amylopectin (S / T ) Range is 3 or more and 3.3 or less. Based on these results, the range of the apparent content of amylose is 15% by mass or more and 30% by mass or less, preferably 15% by mass or more and 21% by mass or less. The range of the very long chain of amylopectin Is in the range of 2.5% by mass or more and 4% by mass or less, and the range of the ratio (S / T) of the mass% (S) of the short chain to the mass% (T) of the long chain of amylopectin is 2.5. It can be said that it is 4 or less, preferably 3 or more and 3.4 or less.

  The rice flour of the present invention, the rice flour for bread containing brown rice flour, the mixed flour for bread containing this rice flour, the bread produced using this rice flour or the mixed flour, and the method for producing bread are comparable to the bread produced with wheat flour. The large volume and softness can be realized, and it can be widely used in the food industry.

Claims (4)

  Amylose with an apparent content of 15% by mass or more and 30% by mass or less, ultralong chain within a range of 2.5% by mass or more and 5.0% by mass or less, and mass% of long chain A bread rice flour characterized by comprising (T) and amylopectin in which the ratio (S / T) of short chain mass% (S) is in the range of 2.5 or more and 4 or less.   Bread mixed flour comprising the rice flour for bread according to claim 1.   A bread produced using the bread flour according to claim 1 or the bread flour according to claim 2. Amylose with an apparent content of 15% by mass or more and 30% by mass or less, ultralong chain within a range of 2.5% by mass or more and 5.0% by mass or less, and mass% of long chain A step of selecting rice flour containing (T) and amylopectin having a short chain mass% (S) ratio (S / T) of 2.5 or more and 4 or less as rice flour for bread;
A step of preparing bread mixed flour containing the selected bread rice flour;
And a step of obtaining rice flour bread with the prepared bread mix powder.