Solid-state fermented food containing miscellaneous grains and preparation method thereof

Abstract

The present invention discloses a solid-state fermented food containing miscellaneous grains and a preparation method thereof. The multi-species solid-state fermentation agent of yeast, lactic acid bacteria, mold, Neurospora and Bacillus provided by the present invention is suitable for solid-state fermentation of grain raw materials (the mass proportion of miscellaneous grains is ≥50%), and has a wide range of applications. The multi-species solid-state fermentation agent combination provided by the present invention can be used to produce miscellaneous grain noodles, miscellaneous grain bread, miscellaneous grain rice, miscellaneous grain porridge, miscellaneous grain rice cakes and other foods containing miscellaneous grains, and the maximum reduction in anti-nutritional factors such as phytic acid, tannins and saponins can reach 73.79%, 56.02% and 77.11% respectively, the maximum reduction in bitterness value can reach 75.35%, and the maximum antioxidant activity is increased to 4.65 times that of unfermented products, which is of great significance to improving the quality of miscellaneous grain foods.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a solid-state fermented food containing miscellaneous grains and a preparation method thereof. Background Art

[0002] Coarse grains usually refer to grain and bean crops other than the five major crops of rice, wheat, corn, soybeans and potatoes, including sorghum, millet, buckwheat, barley, wild rice, mung beans, peas, black beans, red beans, etc. At present, with the continuous deepening of research on the physiological functions of coarse grains, many nutrients and bioactive substances in coarse grains that have health benefits for the human body are gradually recognized and paid attention to. In addition to rich nutrients, coarse grains also contain natural anti-nutritional factors such as phytic acid, tannins, saponins, protease inhibitors, and lectins. Studies have shown that these anti-nutritional factors are strongly bound to minerals, proteins, and starch, limiting the solubility, functionality, and bioavailability of the nutrients in coarse grains, and interfering with the digestion and absorption of nutrients by the human body. Especially for vegetarians, children with iron deficiency anemia, and pregnant women, the intake of coarse grains will affect or even block the absorption of nutrients such as protein, minerals, and functional sugars due to their high levels of anti-nutritional factors, which greatly limits the promotion and application of coarse grains.

[0003] Solid-state fermentation refers to a microbial fermentation method in which microorganisms grow on a matrix (or substrate) with less or no water content. It can soften the matrix structure through the biochemical modification process of microorganisms and their enzymes, promote the degradation and biotransformation of undesirable active ingredients, release bound bioactive compounds, effectively improve the nutritional and edible value of the matrix (or substrate), and increase flavor substances. Compared with liquid fermentation, solid-state fermentation has higher fermentation productivity, lower catabolism inhibition, lower water activity and lower aseptic operation requirements.

[0004] Anti-nutritional factors in grains usually form complex complexes with strong binding with starch, protein, dietary fiber, polyphenolic compounds and minerals, which are difficult to remove by general physical processing methods. Compared with physical processing methods, biological processing (including germination, fermentation and enzyme treatment) is more effective in degrading anti-nutritional factors in grains. Solid-state fermentation of grains can use enzymes produced by microorganisms during fermentation to destroy the strong binding of anti-nutritional factors (phytic acid, tannins, saponins, oligosaccharides, trypsin inhibitors, etc.) with other biological molecules, and decompose these anti-nutritional factors into peptides, free amino acids, phenolic compounds and soluble fibers through microbial metabolism. At the same time, these degradation products produced by bacterial metabolism can significantly increase the content of functional active substances in grains, thereby enhancing the nutritional value and functional activity (such as antioxidant activity) of brown rice. Compared with other biological processing processes (germination and enzyme treatment), a series of small molecular flavor substances are produced during bacterial metabolism, which can give grains unique texture and flavor characteristics. In summary, solid-state fermentation can reduce the content of anti-nutritional factors in grains, improve the flavor of grain products, and improve the functional activity of grain products. However, existing research on solid-state fermentation of grains mostly uses a single strain or a small number of strains, with uncertain processes and limited effects on improving the quality of grains.

[0005] Therefore, it is necessary to provide a method for preparing a food containing whole grains with low anti-nutritional factors, unique flavor and high antioxidant activity, which is of great significance for improving the quality of the food containing whole grains. Summary of the invention

[0006] In order to solve the problems existing in the prior art, one object of the present invention is to provide a method for preparing a solid-state fermented food containing miscellaneous grains.

[0007] Another object of the present invention is to provide a solid-state fermented food containing miscellaneous grains prepared by the method described above.

[0008] To achieve the first purpose, the technical solution adopted by the present invention is:

[0009] The present invention discloses a method for preparing a solid-state fermented food containing miscellaneous grains, comprising the following preparation steps:

[0010] The multi-strain solid fermentation agent A is mixed with the grain raw material for a solid fermentation to obtain a solid fermented grain, and then the multi-strain solid fermentation agent B is mixed with the solid fermented grain for a second solid fermentation to obtain a food containing miscellaneous grains;

[0011] Wherein, the multi-strain solid fermentation agent A includes yeast, lactic acid bacteria, Neurospora, mold and Bacillus, and the mass ratio thereof is 0-1:0-1:0-1:4-12:4-12;

[0012] The multi-strain solid fermentation agent B comprises yeast, lactic acid bacteria, Neurospora, mold and Bacillus, and the mass ratio thereof is 8-20:8-20:8-20:0-1:0-1.

[0013] The present invention adopts yeast, lactic acid bacteria, mold, Neurospora and Bacillus to carry out solid-state fermentation biological modification of grain raw materials (the weight proportion of grains is ≥50%). Compared with untreated grains, solid-state fermentation can utilize the rich and diverse enzymes (phytase, tannase, cellulase, glucanase, xylanase, etc.) produced by microorganisms during the fermentation process to decompose anti-nutritional factors such as phytic acid, tannin, saponin and oligosaccharides (β-glucan and arabinoxylan) in the grain raw materials containing grains into substances such as polypeptides, free amino acids, phenolic compounds and soluble fiber. , effectively reducing the strong combination of anti-nutritional factors with nutrients such as protein, starch and minerals, which helps the digestion and absorption of grains, especially whole grains, in the human body; secondly, the degradation of anti-nutritional factors such as phytic acid, tannins, saponins and oligosaccharides can significantly alleviate the bitter taste and rough taste of whole grain products, which is beneficial to the improvement of sensory quality; further, the degradation of these large-molecule anti-nutritional factors significantly increases the content and effectiveness of small-molecule active substances in whole grains (soluble dietary fiber, free amino acids, free phenolic substances, etc.) and thereby enhances the antioxidant activity of whole grains in vitro. Neurospora edulis contains rich protein, B vitamins, etc., and is a common beneficial bacteria in the fermentation industry. In addition, the phytase, tannin, cellulase, glucanase, xylanase, etc. produced by the metabolism of Neurospora edulis, molds and Bacillus can effectively decompose the phytic acid, tannin, saponin and oligomeric insoluble dietary fiber in grains, produce more carbohydrates that can be used by yeast and lactic acid bacteria, and enhance the adsorption of water by grains, which is conducive to shortening the processing time of grains. A series of small molecular flavor substances are produced in the process of multi-strain metabolism, which gives grains unique texture and flavor characteristics, greatly improving the gray color and poor taste quality of grain products, and improving the edibility of grain products.

[0014] In the early stage, a large number of experiments have found that the multi-species solid fermentation agent A, which is mainly composed of molds and Bacillus, is fermented first, and the multi-species solid fermentation agent B, which is mainly composed of yeast, lactic acid bacteria and Neurospora edulis, is fermented later, which is more conducive to the improvement of the quality of grain products. The reasons are as follows: (1) The large number of enzymes produced by the metabolism of molds and Bacillus, including cellulase, protease, amylase, etc., can soften and loosen the dense cortical structure of grains, which is conducive to the adsorption and passage of external moisture and metabolic enzymes, and improve the biological modification and chemical modification of grain matrix by microorganisms; (2) The rapid growth efficiency and rich metabolites of molds and Bacillus in the multi-species solid fermentation agent A can provide rich nutrients for the growth and metabolism of yeast, lactic acid bacteria and Neurospora edulis in the next step of the multi-species solid fermentation agent B, which is conducive to the formation of small molecules with aromatic odor and antioxidant active substances; (3) A large number of experimental studies in the early stage have found that if the multi-species solid fermentation agents A and B are mixed and fermented once, the competition between the species is very significant, and the functions of some species are limited and cannot play a good role. In summary, the use of multi-strain solid fermentation agents A and B in staged fermentation is more conducive to improving the quality of coarse grain products.

[0015] Further, in the multi-strain solid fermentation agent A, the mass ratio of yeast, lactic acid bacteria, Neurospora, mold and Bacillus is 0.1-1:0.1-1:0.1-1:4-12:4-12; illustratively, the mass ratio of yeast, lactic acid bacteria, Neurospora, mold and Bacillus can also be 0.1-0.2:0.1-0.2:0.1-0.2:4-12:4-12, 0.1-0.2 :0.1~0.2:0.1~0.2:6~10:6~10 or 0.1~1:0.1~1:0.1~1:6~10:6~10 and so on. When the mass ratio of yeast, lactic acid bacteria, Neurospora, mold and Bacillus in the multi-species solid fermentation agent A is 0.1~0.2:0.1~0.2:0.1~0.2:6~10:6~10, the solid fermentation effect on grain raw materials is best.

[0016] Further, in the multi-strain solid fermentation agent B, the mass ratio of yeast, lactic acid bacteria, Neurospora, mold and Bacillus is 8-20:8-20:8-20:0.1-1:0.1-1; illustratively, the mass ratio of yeast, lactic acid bacteria, Neurospora, mold and Bacillus can also be 8-20:8-20:8-20:0.4-0.8:0.4-0.8, 10-18:10-1 8:10-18:0.4-0.8:0.4-0.8 or 10-18:10-18:10-18:0.1-1:0.1-1, etc. When the mass ratio of yeast, lactic acid bacteria, Neurospora, mold and Bacillus in the multi-species solid fermentation agent B is 10-18:10-18:10-18:0.4-0.8:0.4-0.8, the solid-state fermentation effect on cereal raw materials is best.

[0017] Further, the yeast includes but is not limited to one or more combinations of Saccharomyces cerevisiae, Pichia pastoris or Kluyveromyces; the lactic acid bacteria include but are not limited to one or more combinations of Lactobacillus plantarum, Pediococcus pentosaceus, Lactobacillus fermentum or Lactobacillus delbrueckii; the Neurospora includes but is not limited to Neurospora edulis; the mold includes but is not limited to one or more combinations of Monascus, Aspergillus oryzae or Rhizopus oryzae; the Bacillus includes but is not limited to Bacillus coagulans; the yeast, lactic acid bacteria, Neurospora, mold and Bacillus in the multi-strain solid fermentation agent A and the multi-strain solid fermentation agent B may be the same or different in species; the lactic acid bacteria, mold, yeast and Neurospora described in the present invention are freeze-dried; the number of live yeasts, lactic acid bacteria, molds, Neurospora and Bacillus is not less than 1×10 10 cfu / g.

[0018] The yeast, lactic acid bacteria, mold, Neurospora and Bacillus described in the present invention are all from commercially available single pure live bacterial preparations of each species, or bacterial preparations prepared by strict aseptic culture using any known strains identified as corresponding bacterial species by microbiology.

[0019] Further, the material-liquid ratio of the cereal raw material to the multi-strain solid fermentation agent A is 1:0.2-0.7w / v; illustratively, the material-liquid ratio of the cereal raw material to the multi-strain solid fermentation agent A can also be 1:0.2-0.3w / v, 1:0.2-0.4w / v, 1:0.2-0.5w / v, 1:0.2-0.6w / v, 1:0.3-0.4w / v, 1:0.3-0.5w / v, 1:0.3- 0.6w / v, 1:0.3~0.7w / v, 1:0.4~0.5w / v, 1:0.4~0.6w / v, 1:0.4~0.7w / v, 1:0.5~0.6w / v, 1:0.5~0.7w / v or 1:0.6~0.7w / v, etc. When the liquid ratio of the cereal raw material to the multi-strain solid fermentation agent A is 1:0.4~0.6w / v, the solid fermentation effect on the cereal raw material is best.

[0020] Further, the material-liquid ratio of the cereal raw material to the multi-strain solid fermentation agent B is 1:0.5-1.0 w / v; illustratively, the material-liquid ratio of the cereal raw material to the multi-strain solid fermentation agent B can also be 1:0.5-0.6 w / v, 1:0.5-0.7 w / v, 1:0.5-0.8 w / v, 1:0.5-0.9 w / v, 1:0.6-0.7 w / v, 1:0.6-0.8 w / v, 1:0.6 ~0.9w / v, 1:0.6~1.0w / v, 1:0.7~0.8w / v, 1:0.7~0.9w / v, 1:0.7~1.0w / v, 1:0.8~0.9w / v, 1:0.8~1.0w / v or 1:0.9~1.0w / v, etc., when the liquid ratio of the cereal raw material to the multi-strain solid fermentation agent B is 1:0.8~1.0w / v, the solid fermentation effect of the cereal raw material is best.

[0021] Furthermore, the fermentation temperature of the first solid-state fermentation is 25-38°C, and the fermentation time is 24-72h; the fermentation temperature of the second solid-state fermentation is 25-38°C, and the fermentation time is 18-56h; preferably, when the fermentation temperature of the first solid-state fermentation is 30-35°C, and the fermentation time is 28-68h; the fermentation temperature of the second solid-state fermentation is 26-32°C, and the fermentation time is 24-50h, the solid-state fermentation effect on the grain raw materials is best.

[0022] Furthermore, the multi-strain solid fermentation agent A or the multi-strain solid fermentation agent B is prepared according to the following steps:

[0023] First, the required bacterial strains are activated to prepare bacterial mud, and then mixed according to the formula ratio to prepare composite bacterial mud. Finally, sterile water is added to prepare multi-strain solid fermentation agent A or multi-strain solid fermentation agent B.

[0024] Furthermore, the sterile water and the composite bacterial mud are prepared in a ratio of 1.0 to 4.0 g of the total mass of the composite bacterial mud added to every 50 mL of sterile water.

[0025] According to a specific embodiment of the present invention, the yeast, lactic acid bacteria, Neurospora, Bacillus and mold used in the present invention can be activated according to methods known in the art before use to obtain vigorous strains to improve the effect of modifying the grain products. For example, the strain activation can be carried out according to the following method:

[0026] Activation of yeast (e.g., Saccharomyces cerevisiae, aerobic): Inoculate Saccharomyces cerevisiae into a yeast extract powder peptone glucose broth medium without agar, activate for 2 generations, centrifuge at 3000-4000 r / min for 3-5 minutes, wash with 0.8% sterile physiological saline to obtain a precipitated white Saccharomyces cerevisiae mud. The preparation method of the yeast extract powder peptone glucose broth medium without agar is as follows: 10g peptone, 5g yeast extract powder, 20g glucose, mix and add to 1000mL distilled water, heat and boil to dissolve, put into a conical flask and seal, and sterilize at 121℃ for 20min.

[0027] Activation of lactic acid bacteria (for example: plant lactobacillus, aerobic): plant lactobacillus is accessed in the MRS broth that does not contain agar, after activating 2 generations, 3000~4000r / min is centrifuged for 3~5min, with the white plant lactobacillus bacterium mud that obtains precipitation respectively after 0.8% sterile physiological saline washing; The described MRS broth that does not contain agar preparation method is: 10g peptone, 5g beef powder, 20g glucose, 4g yeast powder, 5g sodium acetate, 2g dipotassium hydrogen phosphate, 0.2g magnesium sulfate, 2g triammonium citrate, 0.05g manganese sulfate, 1mL Tween 80, add in 1000mL distilled water after mixing, heat and boil to dissolve, pack into triangular flask and seal, 121 ℃ of high pressure sterilization 20min.

[0028] Activation of Neurospora (e.g. Neurospora edulis, aerobic): The freeze-dried powder of Neurospora edulis is activated and cultured in a PDA medium without agar, and is activated and cultured in a constant temperature incubator at 28°C with constant temperature shaking for 7 days, and then centrifuged at 3000r / min for 5min, and washed 3 times with 0.8% sterile saline to obtain the bacterial mud of Neurospora edulis. The preparation method of the PDA medium without agar is as follows: 200g of potatoes are cut into small pieces, boiled with water for 20 to 30min until they can be pierced by a glass rod, filtered with gauze, the filtrate is heated and 20g of glucose is added, stirred evenly, filled into a conical flask and sealed, and sterilized at 121°C for 20min.

[0029] Activation of Bacillus (e.g., Bacillus coagulans, aerobic): The lyophilized powder of Bacillus coagulans is activated and cultured in LB medium without agar, and is cultured in a constant temperature incubator at 30°C with constant temperature shaking for 7 days, and then centrifuged at 3000r / min for 5 minutes, and washed with 0.8% sterile saline for 3 times to obtain a bacterial sludge of Bacillus. The preparation method of the LB medium without agar is as follows: 10g of peptone, 5g of yeast powder, and 10g of sodium chloride are mixed and added to 1000mL of distilled water, heated and boiled to dissolve, filled into a conical flask and sealed, and sterilized by high pressure at 121°C for 20 minutes.

[0030] Activation of molds (for example, Aspergillus oryzae, Rhizopus oryzae, Monascus purpureus, all of which are aerobic): Aspergillus oryzae, Rhizopus oryzae and Monascus purpureus are inoculated into Cha's liquid medium, potato dextrose liquid medium and malt extract broth medium respectively, activated for 2 generations, centrifuged at 3000-4000 r / min for 3-5 min, washed with 0.8% sterile physiological saline to obtain precipitated Aspergillus oryzae and Rhizopus oryzae mud respectively; the preparation method of Cha's liquid medium is: 30g sucrose, 3g sodium nitrate, 0.5g magnesium sulfate heptahydrate, 0.5g potassium chloride, 0.01g ferrous sulfite tetrahydrate, 1 g potassium hydrogen phosphate, mixed and added into 1000mL distilled water, pH 6.0-6.5, heated and boiled to dissolve, put into a triangular flask and sealed, and sterilized at 121℃ for 20min; the preparation method of the potato glucose liquid culture medium is: 1.0L potato extract (200g peeled potato, cut into small pieces, add 1.0L water and boil for 30min, filter out the potato pieces, and make up the filtrate to 1.0L), 20g glucose, mixed and added into 1000mL distilled water, heated and boiled to dissolve, put into a triangular flask and sealed, and sterilized at 121℃ for 20min. The preparation method of the malt extract broth culture medium is: 6g malt extract powder, 1.8g maltose, 6g glucose and 1.2g yeast extract powder are mixed and added into 1000mL distilled water, heated and boiled to dissolve, put into a triangular flask and sealed, and sterilized at 121℃ for 20min.

[0031] The yeast extract peptone glucose broth medium without agar, the MRS broth medium without agar, the PDA medium without agar, the LB medium without agar, the Czapek liquid medium, the potato dextrose liquid medium and the malt extract broth medium used in the present invention can be purchased from outside or prepared by oneself according to the above method.

[0032] Furthermore, in the cereal raw material, the mass content of coarse grains is 50% to 100%; preferably, the mass content of coarse grains is 50% to 80%; preferably, the coarse grains include but are not limited to one or more of quinoa, sorghum, buckwheat, millet and highland barley; the cereal raw material also includes one or more of wheat, rice, corn, oats, coix, wild rice, mung bean, red bean and black bean. The cereal raw materials in the present invention include but are not limited to whole grains, dehulled grains, cut grains and broken grains.

[0033] The technical solution provided by the present invention is aimed at the application in solid-state fermented foods containing miscellaneous grains. The greater the mass content of the miscellaneous grains, the better the improvement effect, that is, the reduction in the content of phytic acid, tannins and saponins is more obvious, and the increase in antioxidant activity is also more significant.

[0034] According to a specific embodiment of the present invention, the pre-treatment operation of the cereal raw material (the mass proportion of miscellaneous grains is ≥50%) of the present invention is as follows: remove impurities in the cereal raw material by sieving, soak it in drinking water for 2 to 3 hours, and dry it at 40 to 50°C to a moisture content of 10% to 20%.

[0035] To achieve the second purpose, the technical solution adopted by the present invention is:

[0036] The invention discloses a solid-state fermented food containing miscellaneous grains. The food containing miscellaneous grains is prepared according to the preparation method as described above.

[0037] Furthermore, the food containing miscellaneous grains includes miscellaneous grain noodles, miscellaneous grain steamed buns, miscellaneous grain bread, miscellaneous grain rice, miscellaneous grain porridge or miscellaneous grain rice cake.

[0038] Beneficial effects of the present invention:

[0039] The multi-species composite grain solid-state fermentation agent of yeast, lactic acid bacteria, mold, neurospora and bacillus provided by the present invention is suitable for solid-state fermentation of grain raw materials (grain mass accounts for ≥50%), and has a wide range of applications. The multi-species composite brown rice solid-state fermentation agent provided by the present invention can be used to produce grain noodles, grain bread, grain rice, grain porridge, grain rice cakes and other grain-containing foods, and the maximum reduction of anti-nutritional factors such as phytic acid, tannins and saponins can reach 73.79%, 56.02% and 77.11% respectively, the maximum reduction of bitterness value can reach 75.35%, and the maximum increase of antioxidant activity to 4.65 times of unfermented products. In addition, the grains produced by the multi-species solid-state fermentation agent are white and moist, which improves the problem of gray grain color. The grain products have a softer and stickier taste, and a series of small molecular flavor substances are produced through the metabolic process of different strains, giving the grain products unique flavor characteristics, and the taste is more fragrant and rich. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with specific examples. However, these examples are limited to illustrating the present invention and are not intended to limit the scope of the present invention. The methods described in the following examples are conventional methods unless otherwise specified; the materials described are commercially available unless otherwise specified.

[0041] The strains used in the present invention are all commercially available strains, which are derived from the China Industrial Culture Collection Center (CICC), among which the Saccharomyces cerevisiae strain is numbered CICC 1223, the Lactobacillus plantarum strain is numbered CICC 22696, the Aspergillus oryzae strain is numbered CICC 41737, the Rhizopus oryzae strain is numbered CICC 40282, the Monascus purpurogenous strain is numbered CICC 40712, the Bacillus coagulans strain is numbered CICC 24625, the Neurospora vulgaris strain is numbered CICC 40204, the Pediococcus pentosaceus is numbered CICC22145, and the Pichia pastoris is numbered CICC 1688.

[0042] Example 1

[0043] The present embodiment provides a method for preparing solid-state fermented multi-grain rice, wherein the multi-grain rice is mixed with brown rice, buckwheat, sorghum, quinoa, red beans and black beans in a mass ratio of 20%, 20%, 19%, 17%, 16% and 8%;

[0044] The multi-strain solid fermentation agent A contains Saccharomyces cerevisiae, Lactobacillus plantarum, Neurospora edulis, Rhizopus oryzae, Monascus purpureus and Bacillus coagulans, and the multi-strain solid fermentation agent B contains Saccharomyces cerevisiae, Lactobacillus plantarum, Neurospora edulis, Rhizopus oryzae, Monascus purpureus and Bacillus coagulans, and the number of live bacteria of each strain is not less than 1×10 10 cfu / g;

[0045] The preparation method of the solid-state fermented multi-grain rice is as follows:

[0046] (1) Brown rice, buckwheat, sorghum, quinoa, red beans and black beans are sieved to remove other impurities in the materials and then mixed evenly to obtain mixed grains, which are then soaked in drinking water for 3 hours, dried at 40-50° C. to a moisture content of 12%, sterilized at 121° C. for 20 minutes and set aside.

[0047] (2) Saccharomyces cerevisiae, Lactobacillus plantarum, Neurospora glutinosus, Rhizopus oryzae, Monascus purpureus, and Bacillus coagulans were actively cultured according to the above method, and multi-strain solid fermentation agent A was mixed according to the mass ratio of Saccharomyces cerevisiae, Lactobacillus plantarum, Neurospora glutinosus, Rhizopus oryzae, Monascus purpureus, and Bacillus coagulans of 0.1:0.1:0.2:3:5:10, and multi-strain solid fermentation agent B was mixed according to the mass ratio of Saccharomyces cerevisiae, Lactobacillus plantarum, Neurospora glutinosus, Rhizopus oryzae, Monascus purpureus, and Bacillus coagulans of 12:18:15:0.4:0.4:0.3 to prepare two kinds of composite bacterial muds A and B, and the total mass of the composite bacterial mud added to every 50 mL of sterile water was 0.4 g, and multi-strain solid fermentation agent A and multi-strain solid fermentation agent B were prepared.

[0048] (3) Mixed grains and multi-strain solid fermentation agent A were added to a fermentation bag at a material-liquid ratio of 1:0.5 (w / v), sealed, and shaken to allow the mixed grains to be fully soaked. The bag was incubated at 32°C for 48 h and sterilized at 121°C for 20 min.

[0049] (4) The sterilized mixed grains and multi-strain solid fermentation agent B were added to a fermentation bag at a material-liquid ratio of 1:0.8 (w / v), sealed, and shaken to mix the grains and the agent evenly. The bag was incubated at 28° C. for 48 h to obtain the solid-state fermented mixed grains.

[0050] (5) Solid-state fermentation: Mixed grains and drinking water are steamed in an electric rice cooker at a mass ratio of 1:2 for 45 minutes to obtain solid-state fermented grain rice.

[0051] Example 2

[0052] The present embodiment provides a brown rice and multi-grain rice, and the preparation method is the same as that of Example 1, and the difference from Example 1 is that: the multi-species solid fermentation agent A is composed of Pichia pastoris, Pediococcus pentosaceus, Neurospora edulis, Aspergillus oryzae, Rhizopus oryzae, and Bacillus coagulans in a mass ratio of 0.2:0.1:0.1:5:4:8; the multi-species solid fermentation agent B is composed of Pichia pastoris, Pediococcus pentosaceus, Neurospora edulis, Aspergillus oryzae, Rhizopus oryzae, and Bacillus coagulans in a mass ratio of 13:11:17:0.5:0.7.

[0053] Example 3

[0054] This embodiment provides a multi-grain noodle, the bacterial agent is the same as that in embodiment 1, and the method for making the multi-grain noodle is as follows:

[0055] (1) Select high-quality buckwheat and sorghum, sieve to remove impurities, soak in drinking water for 3 hours, dry at 40-50°C until the moisture content is 15%, sterilize at 121°C for 20 minutes and set aside.

[0056] (2) Saccharomyces cerevisiae, Lactobacillus plantarum, Neurospora glutinosus, Rhizopus oryzae, Monascus purpureus, and Bacillus coagulans were actively cultured according to the above method, and multi-strain solid fermentation agent A was mixed according to the mass ratio of Saccharomyces cerevisiae, Lactobacillus plantarum, Neurospora glutinosus, Rhizopus oryzae, Monascus purpureus, and Bacillus coagulans of 0.1:0.1:0.2:3:5:10, and multi-strain solid fermentation agent B was mixed according to the mass ratio of Saccharomyces cerevisiae, Lactobacillus plantarum, Neurospora glutinosus, Rhizopus oryzae, Monascus purpureus, and Bacillus coagulans of 12:18:15:0.4:0.4:0.3 to prepare two kinds of composite bacterial muds A and B, and the total mass of the composite bacterial mud added to every 50 mL of sterile water was 0.4 g, and multi-strain solid fermentation agent A and multi-strain solid fermentation agent B were prepared.

[0057] (3) Mixed grains and multi-strain solid fermentation agent A were added to a fermentation bag at a material-liquid ratio of 1:0.5 (w / v), sealed, and shaken to allow the mixed grains to be fully soaked. The bag was incubated at 32°C for 48 h and sterilized at 121°C for 20 min.

[0058] (4) The sterilized mixed grains and multi-strain solid fermentation agent B are added to a fermentation bag at a material-liquid ratio of 1:0.8 (w / v), and the bag is sealed. The mixed grains and the agent are shaken to mix evenly. The bag is incubated in an incubator at 28° C. for 48 h, dried at 40-50° C. to a moisture content of 10%, and the mixed grains are ground into powder and sieved through a 100-mesh sieve to obtain solid-state fermentation mixed grain powder.

[0059] (5) Weigh 100 g of solid-state fermented mixed grain flour, 100 g of high-gluten wheat flour, 90 mL of water and 4 g of salt into a dough mixer and stir for 5 min until the dough is clumping.

[0060] (6) Place the dough in a proofing box at 30°C and 80% humidity and proof for 45 minutes.

[0061] (7) Place the proofed dough into a noodle making machine and roll it five times until it forms a dough sheet with a thickness of 0.9 to 1.0 mm. Use a cutter to cut the dough into 2 mm wide sheets.

[0062] (8) The noodles are placed in a constant temperature incubator at 30° C. and 85% humidity. Be careful not to overlap the noodles when hanging them to avoid curling after drying. Dry the noodles until the moisture content is about 12%. Cut the noodles into 20 cm lengths and put them into a fresh-keeping bag for later use. This is solid-state fermented multi-grain noodles.

[0063] (9) Weigh 500 mL of distilled water in an induction cooker and keep the water slightly boiling. Weigh about 10 g of solid-state fermented multi-grain noodles and record the mass. Put the noodles into the boiling water, steam for 4 min, then take them out and freeze them in a vacuum freeze dryer at -65 °C for 24 h.

[0064] Comparative Example 1

[0065] This comparative example provides a multi-grain rice, and the preparation method is the same as that of Example 1, and the difference from Example 1 is that: there is no multi-strain solid fermentation agent A and its fermentation process.

[0066] Comparative Example 2

[0067] This comparative example provides a multi-grain rice, and the preparation method is the same as that of Example 1, but the difference from Example 1 is that: there is no multi-strain solid fermentation agent B and its fermentation process.

[0068] Comparative Example 3

[0069] This comparative example provides a multi-grain rice, and the preparation method is the same as that of Example 2. The difference from Example 2 is that during the preparation process, the fermentation processes of multi-strain solid fermentation agent A and multi-strain solid fermentation agent B are swapped, and the multi-strain solid fermentation agents used are swapped.

[0070] Comparative Example 4

[0071] This comparative example provides a multi-grain noodle, and the preparation method is the same as that of Example 3, but the difference from Example 3 is that the multi-strain solid fermentation agent A is a mixture of Rhizopus oryzae and Monascus purpureus in a mass ratio of 3:5.

[0072] Comparative Example 5

[0073] This comparative example provides a multi-grain noodle, and the preparation method is the same as that of Example 3, except that the multi-strain solid fermentation agent B is a mixture of saccharomyces cerevisiae and Neurospora edulis in a mass ratio of 2:3.

[0074] Test Example 1

[0075] Test method:

[0076] (1) Determination of phytic acid content (PC)

[0077] Grind the sample to be tested into powder, accurately weigh 0.1000g of the sample powder to be tested into a glass beaker, add 40mL of 0.5mol / L HCl, and extract under magnetic stirring for 3 hours at room temperature. Take 2mL of the extract and centrifuge at 5000rpm for 4 minutes. Take 0.5mL of the supernatant and add 1mL of ammonium ferric sulfate solution (mass 0.2g NH 4 Fe(SO 4 ) 2 12H 2O was dissolved in 100 mL of 2 mol / L HCl solution), mixed well, heated in a boiling water bath for 30 min, and cooled to room temperature. The test tube was centrifuged at 5000 rpm for 4 minutes. 100 μL of the supernatant was mixed with 150 μL of 2,2′-bipyridine (1% 2,2′-bipyridine and 1% thioglycolic acid mixed in distilled water) solution, and the absorbance was quickly measured at 519 nm at 25°C in a UV spectrophotometer, and distilled water was used as a blank control. A standard curve was drawn using sodium phytate as the standard.

[0078] (2) Determination of tannin content (TC)

[0079] Weigh 1.0000g of sample powder accurately into a glass test tube with a lid, add 2mL of methanol solution and extract in a 40℃ water bath for 6 hours until all powder particles in the test tube are precipitated at the bottom of the test tube and filtered. Repeat the operation 3 times, combine the 3 supernatants and transfer to a centrifuge tube. Finally, a total of 6mL of extract was stored in a refrigerator at 4℃ for analysis.

[0080] The tannin content was determined by the vanillin / hydrochloric acid method. 8% HCl and 1% vanillin were mixed with an equal volume of methanol to prepare a vanillin / HCl solution. 0.1 mL of sorghum extract was placed in a centrifuge tube, and 0.2 mL of vanillin / HCl solution was added. After mixing evenly, the mixture was incubated at 30°C for 20 minutes, and the absorbance was read at 500 nm in a UV spectrophotometer. A standard curve was prepared using a methanol solution of catechins (concentration range 0.1 mg / mL to 2.5 mg / mL).

[0081] (3) Determination of saponin content (SC)

[0082] Take methanol and sample powder and mix them thoroughly at a volume-to-mass ratio of 1:40 (g / mL), heat and reflux continuously at 60°C for 4 hours, and filter in the dark. Recover the sample extract and combine it in a rotary evaporator, and rotary evaporate it at 45°C to enrich saponins. Finally, dissolve it in 30mL of ultrapure water to obtain the saponin solution of the sample and store it in the dark.

[0083] 1 mL of saponin sample solution was drawn into a centrifuge tube, 0.2 mL of vanillin-glacial acetic acid solution and 0.8 mL of perchloric acid were added, and the mixture was placed in a water bath at 60 ° C for 15 min, cooled rapidly, 4.0 mL of ethyl acetate was added, and the mixture was kept in a dark place for 20 min, and the absorbance was measured at 550 nm. A standard curve was drawn with oleanolic acid mass concentration (mg / mL) as the horizontal axis (X) and absorbance as the vertical axis (Y). The sample saponin concentration C was calculated according to the regression equation, and the sample saponin content was calculated according to the following formula.

[0084] The calculation formula of saponin content is:

[0085]

[0086] Wherein, Q is the saponin content (mg / g); C is the saponin concentration (mg / mL); V is the total volume of the extract (mL); and m is the sample mass (g).

[0087] (4) Determination of bitterness

[0088] Use electronic tongue to test the bitterness of the sample. Take 30g sample and crush it, add 100mL reference solution, stir and mix for 10min, centrifuge at 5000rpm for 10min, take the supernatant, filter and perform electronic tongue test. Pour 20mL sample solution into a 100mL sample cup. Soak the bitter sensor in the reference solution for 45s, measure the reference potential, and then soak the sensor in the sample solution for 45s, measure the sample solution potential, and the difference between the two is the bitterness intensity value. Data collection is performed alternately with reference solution and sample solution, and repeated at least 6 times.

[0089] (5) DPPH free radical scavenging ability

[0090] Accurately weigh 2.00 g of sample and put it into a 50 mL plastic centrifuge tube, add 40 mL of methanol, ultrasonically extract (40°C, 100% power, ultrasound for 30 min), centrifuge (3500 r / min for 10 min), take the supernatant, repeat the operation twice, combine the supernatants, evaporate to dryness at 40°C, and then dilute to 2 mL with methanol to obtain the sample extract.

[0091] 600 μL of sample extract dilution was mixed with 3 mL of 0.1 mM / L DPPH methanol solution and then reacted in the dark for 20 minutes. The absorbance was measured at a wavelength of 517 nm, and a methanol solution standard curve was prepared using Trolox as the standard. The results were expressed as the equivalent micromoles of Trolox contained in 100 g of dry basis (μmol Trolox / 100 g).

[0092] (6) ABTS+ free radical scavenging ability

[0093] Add 1 g MnO to 20 mL of 5 mmol / LABTS solution. 2After 30 minutes of reaction at room temperature in the dark, ABTS+· stock solution was formed. Before the measurement, it was diluted with pH 7.4 phosphate buffer solution to an ABTS+· working solution with an absorbance of 0.7±0.02 at 734nm. 200uL of sample dilution solution was mixed with 3mL ABTS+· working solution and reacted at room temperature in the dark for 6 minutes. The absorbance was measured at 734nm. Trolox was used as the standard sample to prepare a standard curve. The results were expressed as the equivalent micromoles of Trolox contained in 100g of the base (μmol Trolox / 100g).

[0094] Results comparison:

[0095] Table 1 shows the phytic acid, tannin and saponin contents and bitterness values ​​in coarse grain rice and coarse grain noodles. For coarse grain rice, compared with the sample without solid-state fermentation, after solid-state fermentation, the phytic acid, tannin and saponin contents in the samples of Examples 1 and 2 were significantly reduced, with the maximum reductions reaching 73.79%, 56.02% and 77.11%, respectively. Compared with Comparative Examples 1, 2 and 3, the reductions in phytic acid, tannin and saponin contents in Examples 1 and 2 were more obvious. For coarse grain noodles, compared with the sample without solid-state fermentation, after solid-state fermentation, the phytic acid, tannin and saponin contents in Example 3 were also significantly reduced, and the reduction was significantly greater than that in Comparative Examples 4 and 5. All of the above illustrate that the use of the solid-state fermentation bacterial agent and method used in the present invention is more conducive to the degradation of anti-nutritional factors. Compared with the samples without solid-state fermentation (coarse grain rice and coarse grain noodles), although the bitterness value of the control example also decreased significantly, the decrease was significantly smaller than that of the embodiment (the maximum decrease in the bitterness value of the embodiment compared with the control was 75.35%), indicating that the solid-state fermentation bacteria agent and method used in the present invention can more effectively reduce the bitterness value of the coarse grain products and give the coarse grain products a more pleasant taste.

[0096] Table 1 Comparison of phytic acid, tannin and saponin content and bitterness value of multi-grain rice and multi-grain noodles

[0097]

[0098]

[0099] Note: PC is phytic acid content (g / 100g), TC is tannin content (mg / 100g), SC is saponin content (mg / g).

[0100] Table 2 shows the comparison results of DPPH free radical scavenging ability and ABTS free radical scavenging ability of multi-grain rice and multi-grain noodles. After solid-state fermentation, compared with the comparative example, the DPPH and ABTS free radical scavenging ability in the embodiment using the solid-state fermentation agent and method of the present invention increased more significantly, and the DPPH and ABTS free radical scavenging ability could be increased to 4.65 times and 3.86 times of the original value, respectively.

[0101] Table 2 Comparison of DPPH free radical scavenging ability and ABTS free radical scavenging ability of multi-grain rice and multi-grain noodles

[0102]

[0103] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a solid-state fermented food containing grains, It is characterized in that The method comprises the following preparation steps: The multi-strain solid fermentation agent A is mixed with the grain raw material for a solid fermentation to obtain a solid fermented grain, and then the multi-strain solid fermentation agent B is mixed with the solid fermented grain for a second solid fermentation to obtain a food containing miscellaneous grains; Wherein, the multi-strain solid fermentation agent A includes yeast, lactic acid bacteria, Neurospora, mold and Bacillus, and the mass ratio thereof is 0.1-0.2:0.1-0.2:0.1-0.2:6-10:6-10; The multi-strain solid fermentation agent B includes yeast, lactic acid bacteria, Neurospora, mold and Bacillus, and the mass ratio thereof is 10-18:10-18:10-18:0.4-0.8:0.4-0.8; The yeast is one or more combinations of Saccharomyces cerevisiae, Pichia pastoris or Kluyveromyces; the lactic acid bacteria is one or more combinations of Lactobacillus plantarum, Pediococcus pentosaceus, Lactobacillus fermentum or Lactobacillus delbrueckii; the Neurospora is Neurospora edulis; the mold is one or more combinations of Monascus, Aspergillus oryzae or Rhizopus oryzae; the Bacillus is Bacillus coagulans; The number of live yeast, lactic acid bacteria, mold, Neurospora and Bacillus is not less than 1×10 10 cfu / g; The material-liquid ratio of the cereal raw material to the multi-strain solid fermentation agent A is 1:0.2-0.7 w / v; the material-liquid ratio of the cereal raw material to the multi-strain solid fermentation agent B is 1:0.5-1.0 w / v; The multi-strain solid fermentation agent A or the multi-strain solid fermentation agent B is prepared according to the following steps: First, the required strains are activated to prepare bacterial mud, then mixed according to the formula ratio to prepare composite bacterial mud, and finally sterile water is added to prepare a multi-strain solid fermentation agent A or a multi-strain solid fermentation agent B; The sterile water and the composite bacterial mud are prepared in a ratio of 1.0-4.0 g of the total mass of the composite bacterial mud per 50 mL of sterile water.

2. The preparation method according to claim 1, It is characterized in that In the multi-strain solid fermentation agent A and the multi-strain solid fermentation agent B, the strain types of yeast, lactic acid bacteria, Neurospora, mold and Bacillus are the same or different.

3. The preparation method according to claim 1, It is characterized in that The material-liquid ratio of the cereal raw material to the multi-strain solid fermentation agent A is 1:0.4-0.6 w / v; the material-liquid ratio of the cereal raw material to the multi-strain solid fermentation agent B is 1:0.8-1.0 w / v.

4. The preparation method according to claim 1, It is characterized in that The fermentation temperature of the first solid-state fermentation is 25-38°C, and the fermentation time is 24-72 hours; the fermentation temperature of the second solid-state fermentation is 25-38°C, and the fermentation time is 18-56 hours.

5. The preparation method according to claim 1, It is characterized in that The fermentation temperature of the first solid-state fermentation is 30-35°C, and the fermentation time is 28-68 hours; the fermentation temperature of the second solid-state fermentation is 26-32°C, and the fermentation time is 24-50 hours.

6. The preparation method according to claim 1, It is characterized in that In the cereal raw materials, the mass content of miscellaneous grains is 50% to 100%.

7. The preparation method according to claim 6, It is characterized in that The mass content of miscellaneous grains is 50%~80%.

8. The preparation method according to claim 6, It is characterized in that The miscellaneous grains include one or more of quinoa, sorghum, buckwheat and highland barley; the cereal raw materials also include one or more of wheat, rice, corn, oats, coix, wild rice, mung bean, red bean and black bean.

9. A solid-state fermented food containing grains, It is characterized in that The food containing miscellaneous grains is prepared according to the preparation method according to any one of claims 1 to 8.

10. The food according to claim 9, It is characterized in that The food containing miscellaneous grains includes miscellaneous grain noodles, miscellaneous grain steamed buns, miscellaneous grain bread, miscellaneous grain rice, miscellaneous grain porridge or miscellaneous grain rice cake.

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