Fermented starter suitable for addition to high-hydration bread

Abstract

To provide a fermented starter which prevents bread dough from becoming slack even when added in a large amount as a secondary ingredient, and which does not affect bread baking performance and bread quality even when the bread dough contains water exceeding wheat flour's inherent absorption capacity.SOLUTION: A lactic acid bacterium that does not exhibit GshR activity was selected as a lactic acid bacterium used in a fermented starter.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a fermentation starter that can be added to high-moisture bread.

Background Art

[0002] As a method for improving the texture of bread without incurring costs, there is a bread-making method called the high-moisture method, which increases the amount of water blended. The water added to high-moisture bread is usually 70 parts by weight or more with respect to 100 parts by weight of wheat flour, and this blending amount exceeds the water retention capacity (water absorption amount) of wheat starch. Therefore, the hydration by wheat starch cannot catch up and bleeding occurs, and the bread dough loses its shape-retaining property and becomes fluid, so the bread-making operations after mixing are extremely difficult. If the bread dough is baked in such a non-uniform state with poor cohesion of the dough, the baked bread will lack moisture, be easily crumbly, and be prone to aging.

[0003] Therefore, in the prior art of high-moisture bread, compositions and manufacturing methods that can suppress water separation, eliminate the stickiness of the bread dough, and modify the texture of the bread have been disclosed. For example, Patent Document 1 uses a tangible water for high-moisture bread in which konjac flour, starch, and water are formed into a jelly-like solid by a hydration gel reaction between an alkaline coagulant and the glucomannan of konjac flour, and immersed in an acid solution to adjust the pH from neutral to acidic. Patent Document 2 uses sodium carboxymethylcellulose having an etherification degree in the range of 0.7-1.2. Patent Documents 3 and 4 disclose a method of mixing a water-insoluble and water-swellable dietary fiber into an oil-in-water emulsion and then kneading it with the bread dough, and Patent Document 5 discloses a method of mixing a water-insoluble and water-swellable dietary fiber into flower pastes in the form of a starch gel and then kneading it with the bread dough. In addition, methods using glycerin organic acid fatty acid esters (Patent Document 6), methods using a plasticized oil composition composed of oil, an emulsifier, and water with polyglycerol fatty acid ester as an emulsifier (Patent Document 7), methods of preparing a tangzhong (pre-ferment) (Patent Document 8), methods using a high-moisture agar gel containing low-strength agar (Patent Document 9), methods of adding water in two steps (Patent Document 10), methods of adding transglutaminase and oil to the sponge dough in the sponge method to improve the elasticity and shape retention of the dough in advance and improve the cohesion with the final dough (Patent Document 11), etc. have been disclosed. Thus, various ingenuities are required for bread making by the high-moisture manufacturing method. As a result, the high-moisture bread produced is characterized by a moist elasticity and a moist texture, which meets the current consumer preferences. However, high technical skills are required for manufacturing.

[0004] On the one hand, the fermentation starter or fermentation flavoring agent (hereinafter collectively referred to as the fermentation starter), which is a secondary raw material for bread, is a fermented food obtained by fermenting cereal flour, fruits and vegetables, milk raw materials, etc. with yeast or lactic acid bacteria, and is mainly used for imparting flavor to bread. However, the addition amount of the fermentation starter is usually about 3 to 5 parts by weight based on 100 parts by weight of cereal flour. If added in a large amount, the bread dough will sag. Therefore, when adding the fermentation starter, it is necessary to adjust the properties of the bread dough by reducing the amount of water corresponding to half of the addition amount. Using the fermentation starter in the high-water-added bread characterized by the large amount of water added requires advanced technology or cannot be manufactured unless the physical properties of the dough are modified with auxiliary materials other than the fermentation starter.

[0005] There are multiple factors that make the bread dough prone to sag due to the addition of the fermentation starter. One of the factors is considered to be that the generation of organic acids by yeast or lactic acid bacteria reduces the pH of the wheat dough, activates the acidic protease inherent in the wheat flour, and partially decomposes the gluten, softening the dough. Another factor is that the main lactic acid bacteria growing in the fermentation starter produce glutathione reductase (GshR), which decomposes the disulfide bonds (S-S bonds) of the glutenin macropolymers (GMP) in the fermentation starter, that is, the cross-linking bonds of gluten, softening the dough of the fermentation starter. Since the fermentation starter with cleaved S-S bonds contains a large amount of thiol groups that act as reducing agents, it is suggested that it also affects the gluten formation of the bread dough when used as a secondary raw material for bread. (Non-Patent Document 1 and Non-Patent Document 2)

[0006] On the other hand, Non-Patent Document 1 and Non-Patent Document 2 report Limosilactobacillus pontis (formerly Lactobacillus pontis), Limosilactobacillus reuteri (formerly Lactobacillus reuteri), Latilactobacillus sakei subsp. sakei (formerly Lactobacillus sakei), SchleiferiLactobacillus perolens (formerly Lactobacillus perolens), etc. as lactic acid bacteria having no GshR activity, and it has also been reported that the fermentation starters obtained from these lactic acid bacteria had little increase or decrease in thiol groups before and after fermentation. However, there has been no report yet on the influence and effect of adding fermentation starters fermented with lactic acid bacteria having no GshR activity to bread dough, especially to high-moisture bread.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

[0008] [Non-Patent Document 1] Andre´ Ja‥nsch, Maher Korakli, Rudi F. Vogel, and Michael G. Ga‥nzle:Glutathione Reductase from Lactobacillus sanfranciscensis DSM20451T: Contribution to Oxygen Tolerance and Thiol Exchange Reactions in Wheat Sourdoughs. APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 73, pp. 4469-‘76. 2007 [Non-Patent Document 2] Nicoline Vermeulen, Jan Kretzer, Hetty Machalitza, Rudi F. Vogel, Michael G. Ga‥nzle:Influence of redox-reactions catalysed by homo- and hetero-fermentative lactobacilli on gluten in wheat sourdoughs. Journal of Cereal Science, 43, pp.137-143, 2006. [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] The problem to be solved by the present invention is to provide a fermentation starter that does not cause the bread dough to sag even when added in a large amount as a bread adjunct material, and that does not affect the bread-making properties and the quality of the bread even when it contains water exceeding the water absorption capacity of wheat flour, and to provide a fermentation starter capable of imparting flavor, which is an effect of adding the fermentation starter.

Means for Solving the Problem

[0010] As a result of intensive research on solving the above problems, the present inventor has found that by using lactic acid bacteria that do not exhibit GshR activity in the production of fermentation starters, even if a large amount of the fermentation starters is added as a secondary raw material for bread, the bread dough does not become sticky, and even if water exceeding the water absorption of wheat flour such as in high-hydration bread is blended, the bread-making properties and the quality of the bread can be made unaffected. Thus, the present invention has been achieved.

[0011] That is, the present invention provides: (1) A fermentation starter having a thiol group (SH group) content of 8 μM or less per 1 g of the fermentation starter, (2) The fermentation starter according to (1) above, fermented with lactic acid bacteria having no GshR activity, (3) The fermentation starter according to (1) to (2) above, wherein the lactic acid bacteria are selected from any one or more of Limosilactobacillus pontis, Lactobacillus helveticus, Limosilactobacillus reuteri, Latilactobacillus sakei subsp. sakei, and Schleiferi Lactobacillus perolens, (4) A method for producing bread dough, comprising a step of adding the fermentation starter according to (1) to (3) above so that the total moisture content becomes 71 parts by weight or more and 75 parts by weight or less with respect to 100 parts by weight of the cereal flour, (5) Bread dough obtained by the production method according to (4) above, and provides the above.

Advantages of the Invention

[0012] According to the present invention, a fermentation starter fermented with lactic acid bacteria having no GshR activity can be added to bread containing a large amount of water, such as extra-moist bread, as a secondary raw material for bread, enabling bread production without deteriorating the bread-making properties, and providing bread with good appearance, texture, and flavor.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0014] In the present invention, GshR is an NADPH-dependent reductase that converts oxidized glutathione (GSSG) to reduced glutathione (GSH). Some lactic acid bacteria that grow in the fermentation starter have GshR activity and can grow with oxygen stress resistance under aerobic conditions by reducing GSSG endogenous in the bacterial cells to GSH. Further, in a fermentation starter based on wheat flour, GshR produced by lactic acid bacteria also acts as a reductase outside the bacterial cells, cleaving the disulfide bond (S-S bond) of gluten macropolymers (GMP) in the fermentation starter, that is, the cross-linked structure of gluten. As a result, the dough of the fermentation starter softens, and a fermentation starter containing a large amount of thiol groups (SH groups) is obtained.

[0015] GshR has been confirmed to be active in Cyanobacterium anabaena, Pseudomonas aeruginosa, Streptococcus thermophiles, Enterococcus faecalis, Lactococcus lactis, and Fructilactobacillus sanfranciscensis, and the nucleotide sequences of the genes have also been reported. For example, the open reading frame gshR of GshR in Fructilactobacillus sanfranciscensis is present on the chromosome and encodes a protein with a deduced molecular weight of 48,614 Da consisting of 446 amino acids and an isoelectric point pI of 4.79.

[0016] The presence and intensity of GshR activity can be measured using a commercially available measurement kit for the enzyme or according to the method described in Non-Patent Document 1. If a correlation can be obtained among the measurement methods, it is not limited to only these measurement methods. Since GshR is also contained in wheat flour dough without culturing lactic acid bacteria, to confirm the presence or absence of GshR activity in lactic acid bacteria, compare the fermented dough obtained by fermenting wheat flour with lactic acid bacteria and the acidic dough of wheat flour with the same pH value as the fermented dough. If it is significantly inferred that GshR is present, it is judged to be active.

[0017] As a commercially available measurement kit, it is used when directly measuring GshR. Oxiselect TM Glutathione Reductase Assay Kit (manufactured by CELL BIOLAB Inc.), Glutathione Reductase (GR) Assay Kit (manufactured by Northwest Life Science Specialities LLC), Glutathione Redustase Fluorescent Kit (manufactured by Arbor Assay), and Glutathione Reductase Kit (manufactured by Randox Laboratories Ltd.) can be used. The measurement procedure may follow the method recommended by each kit.

[0018] The measurement method described in Non-Patent Document 1 is a method of confirming the activity of GshR by measuring the thiol group as a reactant. The fermentation broth is mixed with 50 mM sodium phosphate buffer (pH 6.9) containing sodium dodecyl sulfate (SDS) (fermentation broth: the buffer = 1:10) to prepare a fermentation broth extract. Using the obtained fermentation broth extract, a reaction mixture composed of the following (i) to (iv) is prepared. Reaction mixture (i) Sodium phosphate buffer: 5 mM EDTA = 1:1 640 μL (ii) 10 mM GSSG 120 μL (iii) 1 mM NADPH 100 μL (iv) Fermentation broth extract 100 μL The reaction mixture is reacted at 25 °C under darkroom conditions for 30 minutes. The amount of GSH is measured by mixing 20 μL of reagent A (39.6 mg of DTNB (5,5-dithiobis-2-nitrobenzoic acid) dissolved in 10 mL of 0.5 mM sodium phosphate buffer and adjusted to pH 7.0) with 225 μL of the reaction mixture, measuring at an excitation wavelength of 405 nm, and measuring the thiol group concentration in the fermentation broth.

[0019] In the present invention, lactic acid bacteria without GshR activity refer to lactic acid bacteria that do not have the ability to produce GshR or the produced GshR is inactive, and are not limited by the reason why the enzyme is inactive. Specific examples of lactic acid bacteria without GshR activity include Limosilactobacillus reuteri, Limosilactobacillus pontis, Latilactobacillus sakei subsp. sakei, SchleiferiLactobacillus perolens, etc., and any of these lactic acid bacteria can be used as the priority bacterial species of the fermentation species. Not limited to these bacterial species, as a method for obtaining lactic acid bacteria without GshR activity, for example, lactic acid bacteria growing in the fermentation species can be isolated and cultured, and the GshR activity of the culture solution can be examined, and strains with inactivity can be used, or the gshR gene can be disrupted to use a gshR-deficient strain. As a method for disrupting the gshR gene, in addition to the method by natural breeding, methods for inducing mutations by adding mutagens, ultraviolet irradiation, radiation irradiation, etc., methods for generating random mutations by Insertion Sequence, transposon, etc., or site-specific gene disruption methods by single crossover and double crossover can be applied. In addition, the lactic acid bacteria used in the fermentation species need to be lactic acid bacteria that can grow well and ferment when using cereal powder, vegetables or fruits, milk or dairy products alone or in combination as a substrate. For example, Enterococcus durans, Companilactobacillus alimentarius (formerly Lactobacillus alimentarius), Levilactobacillus brevis (formerly Lactobacillus brevis), Lactobacillus delburueckii subsp.Lactobacillus bulgaricus), Lacticaseibacillus casei (formerly Lactobacillus casei), Companilactobacillus farciminis (formerly Lactobacillus farciminis), Limosilactobacillus fermentum (formerly Lactobacillus fermentum), Fructilactobacillus fructivorans (formerly Lactobacillus fructivorans), Lactobacillus gallinarum, Lactobacillus gasseri, Lactobacillus helveticus, Levilactobacillus namurensis (formerly Lactobacillus namurensis), Companilactobacillus paralimentarius (formerly Lactobacillus paralimentarius), Lactiplantibacillus plantarum subsp. plantarumLactobacillus plantarum (formerly Lactobacillus plantarum), Furfurilactobacillus rossiae (formerly Lactobacillus rossiae), Ligilactobacillus salivarius (formerly Lactobacillus salivarius), Fructilactobacillus sanfranciscensis (formerly Lactobacillus sanfranciscensis), Leuconostoc citreum, Leuconostoc mesenteroides subsp. mesenteroides, Weissella cibaria, Weissella confusa, Weissella paramesenteroides, Pediococcus argentinicus, Pediococcus inopinatus, Pediococcus pentosaceus, Lactococcus lactis subsp. lactis, etc. are listed as candidates. These lactic acid bacteria may be used alone or in combination of two or more species.

[0020] In the present invention, as the yeast capable of co-culturing with lactic acid bacteria having no GshR activity in the fermentation starter, it is desirable that the yeast has no GshR activity or has a low activity level even if it has GshR activity. In addition, the yeast used in the fermentation starter needs to be a yeast that can grow well and ferment when using cereal flour, vegetables or fruits, milk or dairy products, alone or in combination, as a substrate, and is not limited by the differences in bacterial species and strains. For example, Saccharomyces cerevisiae, Saccharomyces rosei, Saccharomyces chevalierii, Saccharomyces florentinus, Saccharomyces exiguous, Saccharomyces bailii, Kluyveromyces lactis, Torulaspora delbrueckii, Candida utilis, Candida kefir, etc. can be mentioned as candidates. These yeasts may be used alone or in combination of two or more.

[0021] The fermentation starter in the present invention is a fermented food obtained by using cereal flour, vegetables, fruits, milk or dairy products, or a combination of two or more of these as a fermentation substrate and fermenting with yeast or lactic acid bacteria, or both of these microorganisms. The fermentation starter is often used as a secondary raw material for bread, and as an additive effect, it can be expected to improve the quality of bakery products such as flavor imparting, texture modification, shelf life improvement, and improvement of the extensibility of bakery dough, and also improve the workability during manufacturing. The fermentation starter may be used by inactivating the growing lactic acid bacteria and yeast with salt or organic acid, and the same additive effect as that of the fermentation starter can be expected for bread as a so-called fermentation flavoring. The fermentation flavoring is useful in that it enables distribution at room temperature and a stable additive effect can be obtained within the shelf life.

[0022] The fermentation starter in the present invention may have any form of powder, liquid, paste or dough, and a substrate such as cereal flour on which lactic acid bacteria and yeast have grown is used. An example of the preparation method is described below. On the first day, cereal flour and water are kneaded until uniform and cultured overnight at a certain temperature. Then, the microorganisms attached to the cereal flour are naturally fermented, and a primary strain dominated by Gram-negative bacteria can be obtained. When the same amount of cereal flour and water are added to this primary strain and kneaded, and cultured in the same manner as on the first day, lactic acid bacteria begin to grow in addition to Gram-negative bacteria, becoming a secondary strain with a different flora. When cereal flour and water are further added and the culture is repeated, a fermentation starter dominated by lactic acid bacteria and yeast can be obtained around the sixth day. The standard for the end of the fermentation process of the fermentation starter is confirmed by measuring the pH value and acidity. The method for measuring the pH value follows the glass electrode method. The ranges of both measured values of the fermentation starter in the present invention are pH 3.0 - 5.5 and acidity 2 - 30 (mL / 10g·0.1N-NaOH) as a guide.

[0023] The cereal flour used as the substrate of the fermentation starter of the present invention can be exemplified by flour prepared by grinding cereals, the endosperm of cereals, or the endosperm with germ and epidermis attached. The cereals described here include wheat, rice (polished rice, glutinous rice), barley, rye, corn, millet, foxtail millet, and adzuki bean, etc. As cereal flour, wheat flour (for example, strong flour, semi-strong flour, medium flour, weak flour, whole grain flour, etc.), rice flour (newly milled flour, high-quality flour, mochi flour, white rice flour, brown rice flour, etc.), barley flour, rye flour (rye whole grain flour or finely ground, medium ground, coarsely ground, stone-ground peeled rye), corn flour, millet flour, foxtail millet flour, adzuki bean flour, etc. can be used. When the cereal flour used in the invention is wheat flour, any one or more of strong flour, semi-strong flour, medium flour, weak flour, and whole grain flour may be used. When fermenting with yeast and lactic acid bacteria, medium flour or weak flour is preferred, and more preferably weak flour, for reasons such as workability and quality stability. These cereal flours may be used alone or in combination of two or more.

[0024] The vegetables or fruits used as the substrate for the fermentation strain of the present invention can include purees or pastes obtained by simply crushing vegetables or fruits, and fruit juices from which skins, seeds, etc. have been removed. Furthermore, as fruit juices, straight juices obtained by crushing and squeezing, concentrated juices (purees, pastes) obtained by concentrating straight juices, and reduced juices of concentrated juices can also be exemplified. The vegetables described herein include solanaceous vegetables such as tomatoes, eggplants, bell peppers, green peppers, and potatoes; umbelliferous vegetables such as carrots, celery, ashitaba, and parsley; brassicaceous vegetables such as cabbages, red cabbages, mizuna (petite veal), Chinese cabbages, pak choi, daikon radishes, kale, cress, komatsuna, broccoli, cauliflower, turnips, wasabi, and mustard; amaranthaceous vegetables such as spinach and beets; asteraceous vegetables such as lettuce, shungiku, salad turnips, burdock, and mugwort; liliaceous vegetables such as onions, garlic, and leeks; cucurbitaceous vegetables such as pumpkins, cucumbers, and bitter gourds; leguminous vegetables such as kidney beans, broad beans, field beans, and edamame; and others such as moringa, asparagus, ginger, sweet potatoes, purple sweet potatoes, perilla, red perilla, and corn. Fruits include citrus fruits such as lemons, oranges, navel oranges, grapefruits, tangerines, limes, sudachi, yuzu, shikuwasa, and tankan; and others such as apples, plums, peaches, strawberries, apricots, plums, prunes, kumquats, pears, European pears, loquats, strawberries, raspberries, blackberries, blackcurrants, cranberries, blueberries, melons, watermelons, kiwifruits, pomegranates, grapes, bananas, guavas, acerolas, pineapples, mangoes, passion fruits, and raisins. These vegetables or fruits may be used alone or in combination of two or more kinds.

[0025] The milk or dairy product used as the substrate for the fermentation starter of the present invention includes raw milk, cow milk, special milk, raw goat milk, pasteurized goat milk, raw ewe milk, partially skimmed milk, skimmed milk, processed milk, cream, cream cheese, butter, cheese, concentrated whey, whipped cream, condensed milk, skimmed condensed milk, unsweetened condensed milk, unsweetened skimmed condensed milk, sweetened condensed milk, sweetened skimmed condensed milk, whole milk powder, cream powder, whey powder, buttermilk powder, sweetened whole milk powder, prepared milk powder, milk beverage, skimmed milk powder, protein concentrated whey powder, casein calcium, casein sodium, casein potassium, casein magnesium, whey protein concentrate, total milk protein, etc. These milks or dairy products may be used alone or in combination of two or more kinds.

[0026] In the fermentation starter of the present invention, as long as it does not inhibit the growth of lactic acid bacteria or yeast, it may be used in combination with other food additives or food materials to impart multiple additive effects. Examples of food additives or food materials that can be used in combination with the liquid starter include, for example, monosaccharides, disaccharides, monoglycerin fatty acid esters, calcium stearoyl lactate, sodium stearoyl lactate, wheat gluten, corn starch, modified dextrin, xylanase, wheat starch, dextrin, processed oils and fats, palm hardened oil, sucrose fatty acid ester, sorbitan fatty acid ester, diacetyl tartaric acid monoglyceride, propylene glycol, guar gum, tricalcium phosphate, α-amylase, β-amylase, glucose oxidase, hemicellulase, protease, potato starch, corn starch, salt, vitamin E, L-ascorbic acid, vitamin C, carotene pigment, lecithin, enzymatically decomposed lecithin, casein sodium, D-sorbitol, yeast extract, cystine, dietary fiber, wheat flour, lipase, phospholipase, reduced maltose syrup, thickening polysaccharides, brewed vinegar, salt, etc.

[0027] It is desirable to add the fermentation starter of the present invention to the wheat flour contained in the bakery dough in an amount of 0.1 to 30 parts by weight, more preferably 5 to 20 parts by weight, and still more preferably 10 to 18 parts by weight. The addition method is not particularly limited. For example, it may be added when mixing after weighing other raw materials, or it may be added after being premixed with other raw materials before being put into the mixing bowl of the mixer. The timing of addition is not particularly limited, and preferably, in terms of being easily compatible with the dough, it is added before or during the mixing of the raw materials.

[0028] In the present invention, bakery products are processed products mainly made from starchy raw materials and manufactured by heat treatment such as baking, frying, steaming, or baking, etc. Examples include breads, dried bread products, cakes, waffles, shu, donuts, fried confectioneries, pies, pizzas, crepes, etc. Examples of breads include meal breads (e.g., white bread, rye bread, French bread, dry bread, variety bread, roll bread, croissant, etc.), cooking breads (e.g., hot dogs, hamburgers, sandwiches, curry bread, pizza pie, etc.), sweet breads (e.g., jam bread, anpan, cream bread, raisin bread, melon bread, sweet roll, brioche, Danish, corona, etc.), steamed breads (e.g., meat buns, Chinese buns, anmian, steamed buns, etc.), special breads (e.g., grissini, muffins, pizza dough, nan, etc.). Examples of dried bread products include rusks and breadcrumbs. Examples of cakes include steamed cakes, sponge cakes, butter cakes, roll cakes, hot cakes, dorayaki, busse, barm cake, pound cake, cheesecake, or snack cakes.

[0029] In the present invention, the high-moisture bread is defined as bread containing 70 parts by weight or more of water based on 100 parts by weight of wheat flour. Except for the high proportion of water, there are no restrictions on the raw materials and manufacturing methods, and it can be combined with conventional bread manufacturing methods (straight method, sponge method, liquid sponge method, sponge dough method, low-temperature aging sponge method, frozen dough manufacturing method, etc.) and formulations (sugar-free dough, low-sugar dough, high-sugar dough, high-sugar and high-fat dough, etc.). There are also no restrictions on the types of bakery products. Since the fermented dough contains moisture, the moisture content is adjusted including the moisture in the fermented dough. In the present invention, the addition amounts of the fermented dough and water are adjusted so that the total moisture content is 71 parts by weight or more and 75 parts by weight or less by combining the moisture in the fermented dough and the added water.

[0030] In the present invention, the volume of the multi-hydrated bread was evaluated by specific volume (cm 3 / g). The measurement of the specific volume was carried out according to the rapeseed displacement method. In the rapeseed displacement method, a container slightly larger than the measurement sample is prepared, filled with rapeseeds, and the upper surface is leveled. The rapeseeds in the container are taken out once, the bread is put into the container, the rapeseeds are returned to the container, and then the upper surface is leveled. The volume of the overflowing rapeseeds is measured with a graduated cylinder. This volume of rapeseeds corresponds to the volume of the measurement sample.

[0031] The sensory evaluation method of the flavor of the bread in the present invention is described. Sensory evaluation was performed on the samples after 1 day of baking by 6 or 9 trained professional panelists (confirmation: confirmed by obtaining data). For the flavor, "fragrant smell", "sour taste", and "sweet taste" were blindly evaluated for comparison group 3 and experimental group 1 or comparison group 3 and comparison group 4. The evaluation was expressed as a score from 1 to 7. In any of the sensory evaluation items, when the characteristic was strongly felt, it was evaluated with a large numerical value, and when it was weakly felt, it was evaluated with a small numerical value. The significance test was performed by a two-sided paired t test with p = 0.05.

[0032] The sensory evaluation method of the texture in the present invention is described. Sensory evaluation was performed on the samples after 1 day of baking by 6 or 9 trained professional panelists. For the texture, "moistness" was evaluated and compared with the non-added group as a reference. The evaluation was expressed as a score from 1 to 7. For "moistness", the closer to 7 points, the more moist it is, and the closer to 1 point, the drier it is. The significance test was performed by a two-sided paired t test with p = 0.05.

Example

[0033] Hereinafter, the present invention will be specifically described using examples and comparative examples. The present invention is not limited thereto.

[0034] (Example 1) · Materials and methods Preparation of fermentation starter Using lactic acid bacteria isolated from the fermentation starter, a fermentation starter was prepared (Figure 1). As the test bacteria, Limosilactobacillus pontis and Lb. helveticus without GshR activity, and Fructilactobacillus sanfranciscensis with GshR activity were used. The experimental group and the control group were set as shown in Table 1. The acidified dough in the control group 2 was wheat dough whose pH was adjusted to the same level as that of the fermentation starter with lactic acid or acetic acid, and it was assumed that no lactic acid bacteria were contained. The raw materials for ingredient adjustment were those that did not affect GshR activity, the dough physical properties of bread, and the flavor.

[0035]

Table 1

[0036] (Example 2) · Materials and Methods: Measurement of GshR Activity The GshR activity was measured for the experimental group 1, the control group 1, and the control group 2. The measurement method conformed to the method described in Non-Patent Document 1.

[0037] · Results: Measurement of GshR Activity Table 2 shows the results of the enzyme activity of the experimental group 1, the control group 1, and the control group 2. The GshR activity is expressed as the concentration of free thiol groups, indicating that the higher the thiol group concentration, the higher the GshR activity. For both the experimental group 1 and the control group 2 fermented with lactic acid bacteria without GshR activity, the average value was in the range of 7 μmol / g. Since there was no difference in the measured values between the experimental group 1 and the control group 2, it was inferred that the lactic acid bacteria Limosilactobacillus pontis in the experimental group 1 either did not have GshR activity or had very low activity even if it had GshR activity. The control group 1 showed a value about twice that of the experimental group 1 and the control group 2, indicating high GshR activity. For confirmation, the GshR activity of the experimental group 2 was also measured in the same way, and the thiol group concentration was similar to that of the experimental group 1.

[0038]

Table 2

[0039] (Example 3) · Materials and methods: Specific volume evaluation of multi - water - added bread (1) The effect of adding fermentation starters to multi - water - added bread was verified. The raw material formulations and manufacturing processes are shown in Tables 3 and 4. In the sponge method, the appropriate mixing ratio of general water is 67% of the flour, and this mixing ratio was set as Comparative Group 3. In the present invention, when evaluating the following examples, Comparative Group 3 was used as a test group that can be evaluated as a control when the manufacturing method is regarded as the sponge method. In contrast, in Experimental Group 1 and Comparative Group 1, the mixing ratio of water is 67% of the flour as in Comparative Group 3, but it is also necessary to correct for the water contained in the fermentation starter. According to Table 1, since the fermentation starter contains half of the water, it is agreed that both Experimental Group 1 and Comparative Group 1 added 75% of water to the flour, and this mixing ratio corresponds to multi - water - added bread. In Comparative Group 4, a commercially available fermentation starter "Sourd Direct AS" (manufactured by Mitsubishi Corporation Life Sciences Co., Ltd.) was added. Regarding the usage method of this commercially available product, it is recommended to subtract half of the added amount of this product from the mixing amount of water to prepare the bread dough. Also, the general added amount of this product is about 5% of the flour. When it is 15% of the flour, it is necessary to adjust the amount of water added further or extend the mixing time according to the properties of the dough during mixing. Since the test groups other than Comparative Group 3 contain salt used for component adjustment in the fermentation starter, the amount of salt was adjusted to be the same as that in Comparative Group 3. In this example, regardless of the properties of the kneaded dough, the mixing time was carried out under the same conditions, and the effect of adding the fermentation starter was evaluated by the specific volume after baking.

[0040] [Table 3]

[0041] [Table 4]

[0042] · Results: Specific volume evaluation of multi - water - added bread (1) The specific volume of the extra - water bread in Example 3 is shown in Table 5. Taking the comparison group 3 with a water blending ratio of 67% relative to flour as 100, the specific volumes of the experimental group 1, comparison group 1, and comparison group 4 were evaluated. Only the experimental group 1 had an increased specific volume. It was shown that the fermentation starter fermented with lactic acid bacteria without GshR activity (Limosilactobacillus pontis) has no effect on the specific volume and can be used as a fermentation starter for extra - water bread. In comparison group 1 and comparison group 4, the specific volume decreased, and it was shown that the fermentation starter fermented with lactic acid bacteria having GshR activity (Fructilactobacillus sanfranciscensis in both test groups) has an adverse effect on the specific volume. In particular, the commercial product "Sourdough Direct AS" in comparison group 4 was developed to show sufficient flavor - imparting effects at a low addition amount (about 5% relative to flour). If the water blending amount was not reduced as recommended, the dough did not come together as dough at the mixing process (no third - time data). From the above, it was shown that the fermentation starter using lactic acid bacteria without GshR activity does not affect the specific volume even when added to extra - water bread.

[0043]

Table 5

[0044] (Example 4) · Materials and methods: Comparison of dough properties in the mixing process of extra - water bread Regarding the soft bread added with a fermentation starter, the stickiness of the bread dough was compared. The formulation of the test groups and raw materials is shown in Table 6. In the present invention, when mixing the main dough by the sponge method, water is added so that it becomes 67% of the flour, and it is stirred with a vertical mixer at low speed for 3 minutes, medium-low speed for 4 minutes, medium-high speed for 1 minute, adding oil and fat, low speed for 2 minutes, medium-low speed for 3 minutes, and medium-high speed for 4 minutes, and this is set as the appropriate mixing conditions. In this example, Comparative Group 3 prepared bread dough under appropriate mixing conditions and was used as a control. When the stickiness of the bread dough is severe, it becomes a property that is difficult to handle throughout each process from mixing to shaping. However, for those skilled in the art with a certain degree of experience, at the time of the mixing process, it is possible to determine whether the bread dough is likely to be sticky and appropriately adjust the stirring conditions to correct the properties of the bread dough. In the present invention, after putting the raw materials of the main dough into a vertical mixer, visually confirm the dough properties at medium-low speed for 4 minutes when all the raw materials are uniformly dispersed and the dough begins to form, and evaluate "stickiness" and "stretchability". For the test groups where the dough did not connect as bread dough, this stirring time was extended until the dough connected. After finishing this stirring, in all the test groups, normal mixing (medium-high speed for 1 minute, adding oil and fat, low speed for 2 minutes, medium-low speed for 3 minutes, medium-high speed for 4 minutes) was performed to obtain the kneaded dough. For the kneaded dough, "stickiness" and "stretchability" were also visually evaluated. The evaluation criteria were classified as follows. Evaluation Criteria for "Stickiness" Less sticky than the dough surface of Comparative Group 3 ······ " - " The same degree as the dough surface of Comparative Group 3 ········ " ± " Slightly stickier than the dough surface of Comparative Group 3 ····· " + " Stickier than the dough surface of Comparative Group 3 ······ " ++ " Much stickier than the dough surface of Comparative Group 3 ··· " +++ " Evaluation Criteria for "Stretchability" Less droopy than the dough of Comparative Group 3 ········ " - " The same degree as the dough of Comparative Group 3 ·········· " ± " Slightly more droopy than the dough of Comparative Group 3 ······· " + " The dough in Comparative Group 3 drips... "++" The dough in Comparative Group 3 drips and is difficult to handle... "+++"

[0045]

Table 6

[0046] · Results: Comparison of dough properties in the mixing process of high - water - content bread Figure 4 shows the properties of the dough observed in the mixing process of high - water - content bread. Comparative Group 3 set as the control, when the medium - low speed mixing for 4 minutes ended, the dough gathered together, hooked onto the hook, without stretching or dripping, and there was no dough left in the mixer bowl. In Comparative Group 5 where 75% water was added based on flour, the dough did not gather together in 4 minutes of medium - low speed mixing, and the stirring time was extended by 7 minutes. A gluten film was formed in the bread dough, but the bread dough was stretchy and prone to dripping, and when the hook was lifted, dough was left in the bowl. In Experimental Group 1 and Experimental Group 2, there was a little dough left in the bowl even after 4 minutes of medium - low speed mixing, and the stirring time was extended by 2 - 4 minutes respectively. After the medium - low speed mixing ended, in both test groups, the bread dough wound around the hook, although it was slightly sticky and stretchy, it had a property that it could be easily taken out of the bowl, and it had no impact on bread - making properties. When 4 minutes of medium - low speed mixing ended in Comparative Group 1, since it showed the same properties as Experimental Group 1 and Experimental Group 2, the stirring time was extended by 5 minutes. When the medium - low speed mixing ended, a gluten film had been formed, but it was a very sticky and stretchy dough, and when the hook was lifted, the dough was left in the bowl, and the bread - making property was very poor. In Comparative Group 2, the bread dough did not gather together in 4 minutes of medium - low speed mixing, and the stirring time was extended by 2 minutes. After the medium - low speed mixing ended, the bread dough was gathered but adhered to the bowl, very sticky, and the bread - making property was poor. From the above, the fermented starter fermented with lactic acid bacteria without GshR had better bread - making properties than the test group (Comparative Group 5) where the same rate of water was added as water when making high - water - content bread, and furthermore, it had no impact on bread - making properties compared to the acidified dough (Comparative Group 2) adjusted to the same pH value and the fermented starter of Fructilactobacillus sanfranciscensis with GshR activity (Comparative Group 1).

[0047] (Example 5) · Materials and methods: Sensory evaluation Sensory evaluation was performed on bread made by the middle - seed method with a general formulation, extra - water bread with the water content increased only with water, and bread using a fermented starter fermented with lactic acid bacteria without GshR. The formulation of the test groups and raw materials is shown in Table 7. In Test Group 1, since the fermented starter contains salt for ingredient adjustment, the salt content ratio was adjusted so that the salt amount was the same as that of the other test groups.

[0048]

Table 7

[0049] · Results: Sensory evaluation The results of the sensory evaluation are shown in Figures 2 and 3. In Figure 2, compared with Comparative Group 3 containing 67% water relative to flour, Comparative Group 5 containing 75% water relative to flour showed a tendency for improved softness compared to Comparative Group 3. On the other hand, when comparing the sourness between the two test groups, Comparative Group 5 showed a tendency to be weaker. Also, there was no difference in the fragrant smell and sweetness. In Figure 3, when comparing Comparative Group 3 containing 67% water relative to flour with Test Group 1 in which a fermented starter fermented with lactic acid bacteria without GshR activity was formulated so that the water content was 75% relative to flour, the softness and sweetness were significantly improved. There was no significant difference in sourness and fragrant smell, but these flavors did not weaken and were equivalent to Test Group 1. Therefore, the bread with 75% water relative to flour added as water (Comparative Group 5) improved the softness, which is an advantage of extra - water bread, but there was no additive effect on flavor imparting. Adding a fermented starter fermented with lactic acid bacteria without GshR activity (Test Group 1) showed that it is possible to impart softness and flavor like extra - water bread.

[0050] As shown in Examples 1-5, the fermented starter fermented with lactic acid bacteria having no GshR activity is a fermented starter that can be used as a raw material for extra-moist bread. The merits obtained by using it are: (a) The bread-making property is better than that of extra-moist bread with an increased water addition amount; (b) When the water is increased, the flavor of the bread becomes thinner, but the flavor can be improved; (c) Unlike the fermented starter fermented with lactic acid bacteria having GshR activity, it is not necessary to subtract and add water according to the addition amount. These points were clarified by the examples.

Industrial Applicability

[0051] As described above, according to the present invention, even when a large amount of the fermented starter fermented with lactic acid bacteria having no GshR activity is added as a bread adjunct, the bread dough does not stick, and even when water exceeding the water absorption of wheat flour such as extra-moist bread is blended, bread with good bread-making property, appearance, texture, and flavor can be provided.

Claims

1. A fermentation starter having a thiol group (SH group) content of 8 μM or less per 1 g of the fermentation starter.

2. The fermentation starter according to claim 1, which is fermented with lactic acid bacteria having no GshR activity.

3. The fermentation starter according to claim 1, wherein the lactic acid bacteria are selected from any one or more of Limosilactobacillus pontis, Lactobacillus helveticus, Limosilactobacillus reuterii, Lactobacillus sakei, and Lactobacillus perolens.

4. The fermentation starter according to claim 2, wherein the lactic acid bacteria are selected from any one or more of Limosilactobacillus pontis, Lactobacillus helveticus, Limosilactobacillus reuterii, Lactobacillus sakei, and Lactobacillus perolens.

5. Bread dough obtained by adding the fermentation starter according to claims 1 to 4 to 100 parts by weight of cereal flour so that the total moisture content is 71 parts by weight or more and 75 parts by weight or less.

6. A method for producing the bread dough according to claim 4.

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