Bread manufactured by fermenting inulin, and manufacturing method of bread dough and bread

Abstract

To provide a manufacturing method of a new bread by which effects of suppressing blood sugar elevation after eating, together with effects of improving conventional bowel movement can be expected with no residue of sugar by using inulin in place of the sugar as saccharide for fermentation.SOLUTION: There is provided a bread manufacturing method by which a bread dough is fermented under no presence of Saccharomyces cerevisiae, the bread manufacturing method comprising the steps of: pre-culturing inulin-assimilating yeast with inulin; fermenting the bread dough containing the inulin without substantially containing sugar, together with the inulin-assimilating yeast that is pre-cultured; and baking the bread dough.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to bread produced using inulin-utilizing yeast and inulin, and a method for producing the same. [Background technology]

[0002] Bread is eaten as one of the staple foods all over the world. There are many kinds of bread, but they are usually made with flour, water, carbohydrates (carbon source for yeast), salt, fat and yeast. Saccharomyces cerevisiae is the main yeast used in making bread, also called baker's yeast. Saccharomyces cerevisiae generally uses sucrose and / or maltose as a carbon source in bread making. However, Saccharomyces cerevisiae does not express inulinase (also called 1-β-D-fructan fructanohydrolase: EC 3.2.1.7) and therefore cannot metabolize inulin. Therefore, inulin could not be used as a carbon source in bread making. Inulinase is an enzyme that breaks down the 1,2-β-fructosidic bond of inulin to produce fructose and oligosaccharides.

[0003] Kluyveromyces spp. (e.g. K. lactis and K. marxianus), which are yeasts that utilize inulin (inulin-utilizing yeasts), are yeasts found in traditional alcoholic fermented milks such as kumis, which is made by fermenting Mongolian horse milk, and are also known as lactose-utilizing yeasts. These yeasts produce β-galactosidase, the most important enzyme for utilizing lactose, and inulinase, which metabolizes inulin.

[0004] Several methods for producing bread using yeast of the genus Kluyveromyces have been reported. Patent Document 1 describes the production of baker's yeast using the freeze-tolerant yeast Kluyveromyces thermotolerans, and the production of bread using this yeast (Claims, Examples).

[0005] Patent Document 2 describes an oil and fat composition for bread and confectionery containing Kluyveromyces lactis (Claims, Examples).

[0006] Patent Document 3 describes the production of bread containing whey powder by mixing cultured cells of Kluyveromyces marxianus and Saccharomyces cerevisiae (Claims, Examples).

[0007] On the other hand, since inulin has an adverse effect on patients with certain diseases, research is being conducted into decomposing inulin contained in wheat flour in order to remove it. Non-Patent Document 1 discloses a method of making bread by adding not only the usual baker's yeast Saccharomyces cerevisiae but also the lactose-utilizing yeast Kluyveromyces marxianus to the dough. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2-142466 [Patent Document 2] JP 2-273137 A [Patent Document 3] JP 2011-76360 A [Non-patent literature]

[0009] [Non-Patent Document 1] J. Agric. Food Chem. 2017, 65, 8704-8713 Summary of the Invention [Problem to be solved by the invention]

[0010] Bread made by adding Kluyveromyces marxianus has existed in the past. However, the purpose of the previous method was to remove inulin from ordinary bread, and it was not possible to produce bread by fermenting bread dough using inulin as a fermentation carbohydrate without using the ordinary baker's yeast Saccharomyces cerevisiae.

[0011] The present invention aims to provide a method for producing a new bread by using inulin instead of sugar, which leaves no residual sugar and is expected to have the effect of suppressing postprandial blood glucose rise in addition to the usual effect of improving bowel movements. [Means for solving the problem]

[0012] Saccharomyces cerevisiae, which is commonly used as baker's yeast, does not express inulinase and is therefore unable to utilize the polysaccharide inulin, whereas Kluyveromyces marxianus, an inulin-utilizing yeast, has inulinase and is therefore able to hydrolyze inulin into fructose and oligosaccharides.

[0013] The present inventors have produced bread (referred to herein as "inulin bread") using only inulin-utilizing yeast as the yeast, without adding sugar or Saccharomyces cerevisiae, and using only wheat flour, inulin, unsalted butter, salt and water as ingredients. Simply using inulin together with inulin-utilizing yeast such as Kluyveromyces marxianus and Kluyveromyces lactis as the yeast in the bread dough would not have made it possible to produce bread similar to that produced by adding conventional Saccharomyces cerevisiae and sugar. As a result of extensive research, the present inventors have found that by using inulin-utilizing yeast such as Kluyveromyces marxianus pre-cultured with inulin as baker's yeast, sufficient fermentation can be achieved by adding inulin alone, without the addition of sugar, and the bread can be easily fermented by Saccharomyces cerevisiae. It was possible to produce bread that was in no way inferior to fermentation using inulin. This bread was compared with a typical bread made using commercially available dry yeast. Various evaluation tests (height, weight, L*, a*, b*, ΔE, hardness and cohesiveness, and sensory evaluation) were performed, and it was found that the inulin bread was not inferior overall to the typical bread. It was also confirmed that similar bread could be produced using Kluyveromyces lactis instead of Kluyveromyces marxianus. From these findings, it was found that various foods can be fermented by using inulin-utilizing yeasts such as Kluyveromyces marxianus and Kluyveromyces lactis pre-cultured with inulin without adding Saccharomyces cerevisiae or sugar, and adding them to bread dough together with inulin.

[0014] The present invention relates to a method for producing an inulin-utilizing yeast cell, comprising the steps of pre-culturing an inulin-utilizing yeast cell together with inulin; Fermenting a bread dough that is substantially sugar-free and contains inulin together with the pre-cultured Kluyveromyces marxianus; Baking the dough; A method for producing bread comprising the steps of: The dough is fermented in the absence of Saccharomyces cerevisiae,

[0015] The present invention also provides the method for producing bread as described above, wherein the inulin-utilizing yeast is Kluyveromyces marxianus or Kluyveromyces lactis.

[0016] The present invention also relates to the method for producing bread, wherein the inulin is from an inulin-containing plant.

[0017] Furthermore, the present invention provides a bread dough comprising an inulin-utilizing yeast precultured with inulin and inulin.

[0018] The present invention also provides the method for producing bread as described above, wherein the inulin is from an inulin-containing plant.

[0019] Furthermore, the present invention provides bread obtained by baking the bread dough produced by the above-mentioned production method. Effect of the Invention

[0020] According to the present invention, inulin-utilizing yeasts such as Kluyveromyces marxianus and Kluyveromyces lactis are used for fermenting bread dough, and are added to bread dough together with inulin, eliminating the need to add sugar, which is normally contained in bread dough. As a result, bread contains inulin, which is dietary fiber, but does not contain any sugar. Therefore, it is expected to have the effect of suppressing the rise in blood sugar level after eating bread. In addition, bread to which inulin and inulin-containing plants have been added contains high-quality dietary fiber, and is expected to have the effect of improving normal bowel movements. [Brief description of the drawings]

[0021] [Figure 1] 2 is a graph showing the height and weight of one embodiment of the pan of the present invention. [Diagram 2] 1A and 1B are side and cross-sectional images of an embodiment of bread of the present invention. [Diagram 3] 1 is a graph showing the relationship between the weight of inulin used in one embodiment of bread of the present invention and the height of the bread. [Figure 4] 2 is a graph showing the hardness and cohesiveness of an example of bread of the present invention. [Diagram 5] 1 is a table showing the L*, a* and b* values ​​and color difference ΔE on the surface and cross section of one embodiment of bread of the present invention. [Figure 6] Graph showing the results of a sensory evaluation of an example of bread of the present invention. [Figure 7] 1A and 1B are side and cross-sectional images of an embodiment of bread of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The method for producing bread of the present invention includes a step of pre-culturing an inulin-utilizing yeast together with inulin, a step of fermenting a bread dough that is substantially sugar-free and contains inulin together with the pre-cultured Kluyveromyces marxianus, and a step of baking the bread dough. Also, in the method for producing bread of the present invention, the bread dough is fermented in the absence of Saccharomyces cerevisiae.

[0023] Inulin-utilizing yeasts are yeasts that express inulinase that metabolizes inulin and can metabolize inulin. Examples of inulin-utilizing yeasts include Kluyveromyces marxianus and Kluyveromyces lactis. Kluyveromyces marxianus is known as one of the lactose-utilizing yeasts, but it is also an inulin-utilizing yeast that expresses inulinase that metabolizes inulin. Kluyveromyces marxianus is available, for example, from the Biotechnology Center of the National Institute of Technology and Evaluation. Kluyveromyces lactis is available, for example, from the Biotechnology Center of the National Institute of Technology and Evaluation. It is expected that this will suppress the rise in blood sugar levels.

[0024] The method for producing bread of the present invention uses only inulin-utilizing yeasts such as Kluyveromyces marxianus and Kluyveromyces lactis as yeasts for fermenting bread dough. In the method for producing bread of the present invention, fermentation of bread dough proceeds only by decomposing inulin by the inulin-utilizing yeasts, so there is no need to add sugar or Saccharomyces cerevisiae to the bread dough. Therefore, bread produced by the method for producing bread of the present invention contains inulin, which is a dietary fiber, but does not contain residual sugar, and is expected to suppress the rise in blood glucose level after a meal.

[0025] In the bread manufacturing method of the present invention, inulin-utilizing yeast such as Kluyveromyces marxianus and Kluyveromyces lactis is pre-cultured with inulin. For example, the inulin-utilizing yeast can be cultured in a medium containing inulin. The medium for pre-culture can be a versatile yeast medium, such as YM medium or YPD medium, to which 1% inulin has been added instead of glucose. For example, the inulin-utilizing yeast is inoculated into YM medium or YPD medium containing 1% inulin instead of glucose, and cultured overnight at 30°C with shaking. After completion of the culture, the cells are collected by centrifugation (4,000 rpm, 3 minutes), washed with water, and used for bread manufacturing. By pre-culturing the inulin-utilizing yeast in an inulin-containing medium, the activity of inulinase in the yeast can be activated, and the inulin utilization ability can be increased. That is, the step of pre-culturing the inulin-utilizing yeast together with inulin is a step of activating the activity of inulinase in the inulin-utilizing yeast and enhancing the inulin assimilation ability.

[0026] In the method for producing bread of the present invention, a bread dough containing substantially no sugar and containing inulin is fermented together with a pre-cultured inulin-utilizing yeast. Inulinase in the pre-cultured inulin-utilizing yeast degrades the 1,2-β-fructoside bond of inulin to produce fructose and oligosaccharides. The pre-cultured inulin-utilizing yeast has activated inulinase, which degrades the inulin in the bread dough and allows the bread dough to be sufficiently fermented.

[0027] The bread dough of the present invention contains at least an inulin-utilizing yeast, cereal flour, and inulin. The bread dough of the present invention may consist only of an inulin-utilizing yeast, cereal flour, and inulin. The bread dough of the present invention may further contain dairy products, fats and oils, and / or salts, in addition to the inulin-utilizing yeast, cereal flour, and inulin. The bread dough of the present invention may consist only of an inulin-utilizing yeast, cereal flour, inulin, dairy products, fats and oils, and salt. The bread dough of the present invention may use Kluyveromyces marxianus or Kluyveromyces lactis as the inulin-utilizing yeast. The inulin-utilizing yeast may be used in combination of one or more types.

[0028] Examples of flours used in the bread dough of the present invention include wheat flour, whole wheat flour, rye flour, barley flour, malt flour, corn flour, oat flour, rice flour, potato starch, arrowroot flour, tapioca flour, and mung bean flour. Examples of flours include strong flour, semi-strong flour, medium strength flour, weak flour, durum flour, and whole wheat flour. As for flours, wheat flour may be used alone, or two or more types of flour may be used in combination, such as wheat flour and another type of flour.

[0029] In the bread manufacturing method of the present invention, the milk used in the bread dough includes, for example, milk, processed milk, concentrated milk, cream, skim milk powder, whole milk powder, condensed milk, fermented milk, etc. Milk includes, for example, raw milk, additive-free milk, milk with no ingredient adjustment, special milk, milk with ingredient adjustment, low-fat milk, and non-fat milk, etc. In the manufacturing method of the present invention, since the inulin-utilizing yeast metabolizes inulin to cause fermentation, the milk used in the bread dough may be a milk that does not contain lactose, such as lactose-removed skim milk.

[0030] In the bread manufacturing method of the present invention, examples of fats and oils used in the bread dough include butter, margarine, shortening, compound margarine, fat spread, powdered fats and oils, rapeseed oil, canola oil, soybean oil, corn oil, olive oil, sunflower oil, safflower oil, sesame oil, perilla oil, linseed oil, palm oil, palm kernel oil, coconut oil, cottonseed oil, grapeseed oil, cacao butter, salad oil, beef tallow, lard, etc. Butter includes salted butter and unsalted butter (butter without salt).

[0031] In the bread making method of the present invention, the salt used in the bread dough means a seasoning containing sodium chloride as a main component, and any food-grade salt product can be suitably used. Examples of salt include table salt, refined salt, sea salt, and rock salt.

[0032] In the method for producing bread of the present invention, the bread dough may not contain any sugar other than inulin as the sugar for fermentation. That is, the sugars contained in the bread dough of the present invention are only the inulin or sugar derived from an inulin-containing plant used as the material for fermentation. In addition, since the inulin-utilizing yeast is used in the present invention, the inulin contained in the dough together with the yeast is decomposed by inulinase, and sufficient fermentation proceeds only by adding inulin without adding sugar, and bread that is in no way inferior to bread fermented by Saccharomyces cerevisiae and sugar can be produced. Therefore, the bread produced by the method of the present invention contains high-quality dietary fiber (inulin) while no sugar remains. In addition, Kluyveromyces marxianus and Kluyveromyces lactis also decompose lactose, so that the sugar content is low and the energy is low compared to bread produced by adding sugar or milk with general baker's yeast.

[0033] In the bread manufacturing method of the present invention, the inulin may be purified inulin or crude inulin extracted from an inulin-containing plant or the like. Also, the inulin may be provided as an inulin-containing plant. The inulin may be, for example, enzymatically synthesized inulin, inulin extracted from Jerusalem artichoke, an unprocessed inulin-containing plant, and an inulin-containing processed product. The unprocessed inulin-containing plant may be, for example, Jerusalem artichoke, dahlia, burdock, onion, garlic, yam, and yacon. Also, the unprocessed inulin-containing plant may be, for example, an inulin-containing part such as a tuberous root. The inulin-containing processed product may be, for example, a dried product, chips, powder, and the like, of the unprocessed inulin-containing plant.

[0034] In the bread manufacturing method of the present invention, the content of inulin in the bread dough is not particularly limited, but can be 1 to 100 parts by weight per 100 parts by weight of grain flour, for example, 2 to 50 parts by weight per 100 parts by weight of grain flour. When inulin is provided as an inulin-containing plant, the content of inulin in the bread dough can be adjusted so that the content of inulin itself in the bread dough is the above ratio.

[0035] In the bread manufacturing method of the present invention, the content of the pre-cultured inulin-utilizing yeast in the bread dough is not particularly limited, but may be 1 to 5 parts by weight wet weight per 100 parts by weight of flour. The content of the inulin-utilizing yeast such as Kluyveromyces marxianus can be reduced by using dried cells. The content of the salt in the bread dough of the present invention is not particularly limited, but may be 0.1 to 5 parts by weight per 100 parts by weight of flour. The content of the oil in the bread dough of the present invention is not particularly limited, but may be 0.1 to 10 parts by weight per 100 parts by weight of flour.

[0036] The method for producing bread of the present invention may further include a step of kneading the pre-cultured inulin-utilizing yeast, inulin, cereal flour, and other ingredients, if any, prior to the step of fermenting the dough. The kneading step can produce a dough. The kneading step may be performed manually or using a commercially available kneading machine.

[0037] The method for producing bread of the present invention may further include a step of pre-fermenting the kneaded dough at room temperature or at 20 to 30° C. for 10 to 30 minutes during or after the kneading step.

[0038] The step of fermenting the dough (fermentation step) can be carried out by leaving the dough to stand under general fermentation conditions. The fermentation temperature is not particularly limited, but may be 20 to 40° C. The fermentation time is not particularly limited, but may be 20 minutes to 2 hours.

[0039] The process of fermenting the dough may be composed of two stages, a primary fermentation and a secondary fermentation. For example, the primary fermentation may be carried out for 10 to 60 minutes at 20 to 35° C., and the secondary fermentation may be carried out for 10 to 60 minutes at 35 to 40° C. The process may further include a step of degassing the dough after the primary fermentation and after the secondary fermentation.

[0040] The process of fermenting the dough may consist of three stages: primary fermentation, secondary fermentation, and final fermentation. The final fermentation (shaping and fermentation process) is a final fermentation before baking, and may be carried out, for example, at 20 to 35° C. for 10 to 60 minutes.

[0041] In the step of baking the dough (baking step), the dough leavened in the leavening step is baked. The baking step is not particularly limited, but the dough may be baked at 150° C. to 230° C. for 10 to 120 minutes, for example.

[0042] A part or all of the above steps may be carried out using a bread machine such as a commercially available home bakery.

[0043] The present invention provides a bread dough containing inulin-utilizing yeast precultured with inulin and inulin. In the bread dough of the present invention, the lactose-utilizing yeast precultured with inulin can be prepared as described in the above-mentioned method for producing bread of the present invention, and the preculture can be, for example, by culturing the inulin-utilizing yeast in a medium containing inulin.

[0044] In the bread dough of the present invention, the inulin may be purified inulin or crude inulin extracted from an inulin-containing plant or the like, as described above in the method for producing bread of the present invention. Inulin may also be provided as an inulin-containing plant.

[0045] In the bread dough of the present invention, the inulin content and the inulin-utilizing yeast content are not particularly limited, but can be the contents as described in the above-mentioned method for producing bread of the present invention.

[0046] The present invention provides bread produced by the above-mentioned method for producing bread of the present invention. The bread of the present invention may be bread obtained by baking the above-mentioned bread dough.

[0047] The bread of the present invention can be in the form of, but is not limited to, bread, croissant, Danish pastry, roll bread, butter roll, French bread, German bread, focaccia, ciabatta, bagel, pizza, naan bread, and the like.

[0048] The present invention provides a processed food material that contains an inulin-utilizing yeast precultured with inulin and inulin, and that is fermented in the absence of Saccharomyces cerevisiae. As described above, inulinase is induced in the inulin-utilizing yeast precultured with inulin, and the yeast is able to metabolize inulin and proceed with fermentation. EXAMPLES

[0049] (yeast) Kluyveromyces marxianus (NBRC 1735) and Kluyveromyces lactis (NBRC 0433) were obtained from the Biotechnology Center, National Institute of Technology and Evaluation, Japan. Kluyveromyces marxianus and Kluyveromyces lactis were precultured overnight at 30°C in a medium containing 10 g / L inulin, 5 g / L peptone, 3 g / L yeast extract, and 3 g / L malt extract, respectively. The precultured Kluyveromyces marxianus and Kluyveromyces lactis cells were washed twice with sterilized water and used for bread making. To compare with Kluyveromyces marxianus, a commercially available dry yeast (Nissin Flour Milling) was also used for bread making (sugar was used instead of inulin).

[0050] (Inulin) The inulin used was an enzyme-synthesized product (Tokyo Kasei). In order to experimentally ensure that fermentation was achieved with inulin, data is shown for bread made using inulin of high purity in this example. When the possibility of substituting a commercial product derived from Jerusalem artichoke (Fuji Nippon Seito) was confirmed, data was obtained that was exactly the same as that of the enzyme-synthesized product. In other words, it was confirmed that bread could be made in the same way whether the enzyme-synthesized product or a commercial product derived from Jerusalem artichoke was used. For this reason, inulin bread made using a commercial product derived from Jerusalem artichoke was used in the sensory evaluation.

[0051] (Height and weight measurements and appearance evaluation) After baking, the bread was cooled at room temperature for 1 hour and then placed in a plastic bag at room temperature for 20 hours. The height and weight of the bread were measured using a ruler and a scale, respectively. Images of the side and cross section of the bread were taken using a digital camera (Canon).

[0052] (Bread color evaluation) The L*, a* and b* values ​​of the bread (surface and cut surface) were measured using a colorimeter (CR-300, Konica Minolta). The overall color difference (ΔE) was calculated from these L*, a* and b* values.

[0053] (Evaluation of the physical properties of bread) The bread was cut into rectangular parallelepipeds (40 mm x 40 mm x 20 mm) using a slicer and a bread cutter. The physical properties (hardness and cohesiveness) of these pieces of bread were measured using a creep meter (TPU type, Yamaden Co., Ltd.). Measurement conditions: plunger, disc type (diameter 8 mm); measurement strain rate 50%; compression speed 5 mm / s.

[0054] (Sensory evaluation) A sensory evaluation test was conducted to evaluate the quality of bread. After removing the crust of the bread, it was cut into cubes (20mm x 20mm x 20mm) using a bread cutter. Twenty-six volunteer tasters aged 18-19 years old evaluated the appearance, color, fragrance, moist feeling, chewy texture, taste and overall quality of the breads using the following criteria. The intensity of the moist feeling and chewy feeling was evaluated. -2: Poor (weak in terms of moistness and chewiness) -1: A little bad (slightly weak in terms of moistness and chewiness) 0:Normal +1: A little good (slightly strong in terms of moistness and chewiness) +2: Good (strong in terms of moistness and chewiness)

[0055] (statistical analysis) Data (height, weight, L*, a*, b*, hardness and cohesiveness) are expressed as the average of measurements for three pieces of each bread of the example and the comparative example. Sensory evaluation data are expressed as the average of the evaluation scores (n=26). Statistical significance between the example and the comparative example was calculated by t-test.

[0056] Example 1: Bread dough containing Kluyveromyces marxianus and inulin Materials and usage: 280g wheat flour (strong flour, Nisshin Flour Milling) Inulin (enzymatically synthesized product, Tokyo Kasei or Jerusalem artichoke-derived commercial product, Fuji Nippon Sugar) 20g, 20g unsalted butter (Snow Brand) Sugar-free skim milk (non-lactate, Morinaga Milk Industry) 6g, Salt (Salt Business Center) 6g, 190mL of tap water, Kluyveromyces marxianus live cells 5g

[0057] The above amounts of each ingredient were mixed. 5 g of live Kluyveromyces marxianus cells were used, either Kluyveromyces marxianus cells precultured with lactose or Kluyveromyces marxianus cells precultured with inulin. Bread was made using a home bakery HBK-101 (MK Seiko Co., Ltd.) in natural yeast mode according to the attached manual. The cooking process in the home bakery HBK-101 consists of a process of kneading the dough, a process of preliminary fermentation, a process of kneading the preliminary fermented dough (about 3 hours up to this point), a process of primary fermentation, a process of secondary fermentation, a process of shaping and fermentation, and a process of baking (about 4 hours from the primary fermentation to the baking process). In addition, (3 hours of preliminary fermentation) indicates data for bread produced in the cooking process after preliminary fermentation for 3 hours before the process of kneading the dough according to the above procedure. (No preliminary fermentation) indicates data for bread produced simply by the above cooking process without preliminary fermentation. That is, (no preliminary fermentation) shows data for bread produced through the steps of kneading the dough, the first fermentation, the second fermentation, the shaping and fermentation, and the baking (approximately 4 hours from the first fermentation to the baking).

[0058] Figure 1 shows the data for bread produced using live Kluyveromyces marxianus cells. 1. Bread made with Kluyveromyces marxianus precultured with lactose (without pre-fermentation) 2: Bread made with K. marxianus precultured with inulin (without pre-fermentation) 3: Bread made with K. marxianus precultured with inulin (pre-fermentation 3 hours)

[0059] When K. marxianus grown on lactose was used, the height of the bread (without pre-fermentation) was 8 cm, and when K. marxianus grown on inulin was used, the height of the bread (without pre-fermentation) was 13.5 cm. This result indicates that K. marxianus pre-cultured with inulin has the effect of promoting fermentation in inulin-containing bread dough, promoting dough rise, and improving bread quality. It is also speculated that inulinase (an inulin-degrading enzyme) is induced by pre-culture of K. marxianus with inulin, which affects bread quality. The rise of the dough made with K. marxianus pre-cultured with inulin changed depending on whether or not it was pre-fermented. The rise of the dough was significantly promoted by setting the pre-fermentation time. It is believed that hydrolysis of high molecular weight inulin progressed during the preliminary fermentation, promoting fermentation by the yeast (Kluyveromyces marxianus).

[0060] Figure 2 shows side and cross-sectional images of bread (without preliminary fermentation) made with Kluyveromyces marxianus pre-cultured with inulin as shown in Figure 1. The bread has a good brown color and small air bubbles are evenly distributed over the entire surface.

[0061] (Example 2) Relationship between the amount of inulin used and the height of bread In the cooking process in the home bakery HBK-101 shown in Example 1, Kluyveromyces marxianus pre-cultured with inulin was used, and bread was produced in the same manner as in Example 1 by changing the amount of inulin (without preliminary fermentation). Bread was produced using 10g, 15g, 20g, and 30g of inulin, with the rest being the same ingredients and amounts as in Example 1. Figure 3 shows the relationship between the amount of inulin used and the height of the bread. Since it was produced in a home bakery, the base area was constant and only the height changed. The height of the bread reached a plateau when 20g or more of inulin was used. In this example, bread produced with 20g of inulin was used.

[0062] (Example 3) Physical properties (texture) of inulin bread In the cooking process in the bread maker HBK-101 shown in Example 1, Kluyveromyces marxianus pre-cultured with inulin was used, and the physical properties (texture) of bread (pre-fermented for 3 hours) produced under the condition of 3 hours of preliminary fermentation was evaluated. As a comparative example, bread produced with normal dry yeast (normal white bread) was used. For the comparative example, bread was produced using dry yeast as follows. Bread was made in normal mode using the bread maker HBK-101 according to the attached manual. After pouring 190 mL of tap water into the bread maker, 2.4 g of dry yeast, 280 g of bread flour, 4 g of salt, 20 g of unsalted butter, 6 g of skim milk (Megmilk Snow Brand Co., Ltd.), and 20 g of sugar (Meiji Sugar Co., Ltd.) were placed in the designated positions of the bread maker. The specific cooking process includes a step of kneading the dough ingredients, a step of resting the kneaded dough for preliminary fermentation, a step of kneading the dough again, a step of first fermentation of the dough, a step of releasing the gas in the dough and then second fermentation, a step of releasing the gas in the dough and then final fermentation, and a baking step.

[0063] A graph of the hardness and cohesiveness of the bread of Example 1 (preliminary fermentation for 3 hours) and the bread of the comparative example (normal white bread) is shown in Figure 4. There was no significant difference in the hardness and cohesiveness of each bread.

[0064] FIG. 5 shows the L*, a*, and b* values ​​and color difference ΔE on the surface and cross section of the bread of Example 1 (3: bread made with Kluyveromyces marxianus pre-cultured with inulin (pre-fermentation for 3 hours) and the bread of the comparative example (normal sliced ​​bread). In both the crumb (bread body) and the crust (bread crust), a noticeable difference was confirmed between the bread made with Kluyveromyces marxianus pre-cultured with inulin (pre-fermentation for 3 hours) and the bread made with the comparative dry yeast (normal sliced ​​bread). However, this difference has almost no effect on the quality of the bread, etc.

[0065] These results indicate that good quality bread can be produced using Kluyveromyces marxianus under the above-mentioned conditions. In other words, by using Kluyveromyces marxianus precultured with inulin to ferment inulin-containing bread dough, and by setting the pre-fermentation time, good quality bread can be produced without using dry yeast and sugar.

[0066] (Sensory evaluation) The results of the sensory evaluation are shown in the graph in Figure 6 (white bars: Comparative example (dry yeast; normal white bread), black bars: Example 1 (inulin bread; 3: bread made with Kluyveromyces marxianus pre-cultured with inulin (pre-fermentation for 3 hours)). Surprisingly, no significant differences were observed between the bread of Example 1 and the bread of Comparative Example 1 in the seven test items (appearance, color, aroma, moistness, chewy texture, taste, and overall quality). However, a tendency for each evaluation to be high was observed.

[0067] From the above results, it was found that the bread made using only Kluyveromyces marxianus and inulin, without adding sugar or Saccharomyces cerevisiae, and using only wheat flour, salt and fats and oils (3 in Example 1: bread made using Kluyveromyces marxianus pre-cultured with inulin (pre-fermentation for 3 hours) was not inferior overall to the typical bread (common white bread) (Comparative example).

[0068] Example 4: Bread dough containing Kluyveromyces lactis and inulin Bread dough containing Kluyveromyces lactis and inulin was prepared by the same procedure as in Example 1, except that Kluyveromyces lactis was used instead of Kluyveromyces marxianus in Example 1. In addition, bread was prepared in the same manner as in Example 1, using bread dough containing Kluyveromyces lactis precultured with inulin.

[0069] FIG. 7 shows side and cross-sectional images of the bread produced in Example 4 above. The bread was well browned, and small air bubbles were evenly distributed over the entire surface. The bread was 11.0 cm tall and weighed 481 g. From the above results, it was found that, regardless of the type of inulin-utilizing yeast, by preparing bread dough using inulin-utilizing yeast pre-cultured with inulin, the bread was not inferior overall to typical bread: the comparative example (normal white bread).

[0070] The method for producing bread dough of the present invention uses inulin instead of sugar, which leaves no residual sugar and the inulin itself has a blood sugar suppressing effect, so in addition to the usual effect of improving bowel movements, it can be expected to have an effect of suppressing postprandial blood sugar rise. [Industrial Applicability]

[0071] The present invention can be suitably used in the production of bread.

Claims

1. A step of pre-culturing an inulin-utilizing yeast together with inulin; Fermenting a bread dough that is substantially sugar-free and contains inulin together with the pre-cultured Kluyveromyces marxianus; Baking the dough; A method for producing bread comprising the steps of: A method for producing bread, wherein the dough is fermented in the absence of Saccharomyces cerevisiae.

2. 2. The method for producing bread according to claim 1, wherein the inulin-utilizing yeast is Kluyveromyces marxianus or Kluyveromyces lactis.

3. The method for producing bread according to claim 1 , wherein the inulin is provided as an inulin-containing plant.

4. Bread dough comprising inulin-utilizing yeast precultured with inulin and inulin.

5. The bread dough of claim 4, wherein the inulin is provided as an inulin-containing plant.

6. Bread obtained by baking the dough according to claim 4 or 5.

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