Low-phytic-acid cereal frozen dough and application thereof in baked food

Abstract

The invention provides low-phytic-acid cereal frozen dough and application thereof in baked food, and the low-phytic-acid cereal frozen dough comprises the following components in parts by weight: 100-150 parts of wheat flour, 70-80 parts of rye flour, 30-50 parts of buckwheat flour, 200-300 parts of water, 8-10 parts of white granulated sugar, 2-3 parts of yeast, 0.03-0.05 part of zinc lactate and 8-10 parts of a rhizopus fermentation product. The rhizopus fermentation product contains phytase and lactic acid, and the phytase and the lactic acid can reduce the phytate content in the cereal frozen dough; meanwhile, zinc lactate can chelate part of lactic acid, and the inhibition effect of lactic acid in a system on yeast growth and fermentation is relieved, so that the fermentation volume and the internal structure of the baked food are improved, and the low-phytic-acid cereal food with excellent quality is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a low-phytic acid cereal frozen dough and application thereof in baked food. Background Art

[0002] Frozen dough is made by using freezing and refrigeration technology. It uses flour as the main raw material, adds yeast, salt, sucrose, eggs, milk powder and other auxiliary materials, adds water and stirs to form dough, and then freezes and refrigerates it. When it is used, it only needs to be thawed, put into the oven and baked to get fresh baked goods. Due to its convenience and large-scale production, it has gradually been accepted by the baking industry. With the changes in the pace of life and dietary habits, baked goods such as bread have become an indispensable food on people's breakfast tables. In daily food, due to the increasing proportion of high-calorie, high-fat, high-protein and refined foods, more and more people prefer high-dietary fiber, low-calorie grain bread. However, whole wheat bread products contain high levels of phytate, which is considered an anti-nutritional factor for humans and animals. It is a cationic chelator for calcium, magnesium, iron and zinc ions, and can also form complexes with the amino acid groups of proteins. A diet rich in phytate will greatly reduce the absorption of minerals in the diet. Therefore, it is of great significance to develop low-phytate cereal foods. Summary of the invention

[0003] Technical problems to be solved: In view of the above technical problems, the purpose of the present invention is to provide a low-phytic acid cereal frozen dough and its application in baked foods, wherein the added Rhizopus fermentation product contains phytase and lactic acid, wherein the phytase can degrade the phytate in the cereal raw materials, and the phytase indirectly acts on α-amylase, so that the volume of baked foods such as bread is increased and the internal structure is also improved; the accumulation of lactic acid makes the system in an acidic environment, the phosphate group of phytic acid will lose part of the negative charge, promote the decomposition of phytic acid and metal ion complexes, thereby improving the utilization rate of minerals; finally, an appropriate amount of zinc lactate can chelate the lactic acid in the system, reduce the inhibitory effect of lactic acid on yeast, increase the specific volume of bread, and improve the quality.

[0004] Technical solution: A low-phytic acid grain frozen dough comprises the following components: by weight, 100-150 parts of wheat flour, 70-80 parts of rye flour, 30-50 parts of buckwheat flour, 200-300 parts of water, 8-10 parts of white sugar, 2-3 parts of yeast, 0.03-0.05 parts of zinc lactate and 8-10 parts of root mold fermentation product. Further, the preparation steps of the root mold fermentation product are specifically as follows: S1. Activate Rhizopus in PDA medium and prepare seed liquid medium, sterilize at 115-121°C for 15-20min; S2. Inoculate a single colony of Rhizopus after activation into the seed liquid culture medium, and culture on a shaker at 30-35°C and 180-200rpm for 1-2 days to obtain a seed liquid; S3. Inoculate the seed liquid into the fermentation medium, culture on a shaker at 28-32°C and 180-200 rpm for 2-3 days, filter the filtrate, sterilize, and dry to obtain the Rhizopus fermentation product. Furthermore, the components of the seed liquid culture medium in step S1 are: glucose 80 g / L, (NH4)2SO4 4 g / L, KH2PO4 0.3 g / L, FeSO4·7H2O 0.44 g / L, and MgSO4·7H2O 0.25 g / L. Furthermore, in step S3, the seed liquid inoculation amount is 5-10%; the fermentation medium components are glucose 160g / L, (NH4)2SO46g / L, KH2PO40.15g / L, FeSO4·7H2O 0.22g / L, MgSO4·7H2O 0.25g / L, NaH2PO40.15g / L, and CaCO380g / L. Furthermore, a method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: Mix wheat flour, rye flour, buckwheat flour, white sugar, dry yeast, zinc lactate and Rhizopus fermentation product, add water, and knead into fresh dough; Step 2: subject the fresh dough to a wet heat treatment at 20-25% RH and 140-145°C for 5-10 minutes, cut the dough into small pieces of 60-80 g, wrap them in plastic wrap, seal them, and quickly freeze them in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C. Frozen the dough can obtain low-phytic acid grain frozen dough. Furthermore, the low-phytic acid cereal frozen dough is used in baked goods. Furthermore, the baked food includes bread and cake. Furthermore, the specific steps of preparing the bread are as follows: Step 1: thawing the low-phytic acid grain frozen dough, shaping it into a bread shape, and placing it at 30-40° C. and 70-80% RH for 20-40 minutes to obtain a proofed dough; Step 2: Bake the proofed dough at 170-200°C for 10-15 minutes and cool it to obtain low-phytic acid grain bread. Beneficial effects: 1. The frozen dough of the present invention is added with a fermentation product of Rhizopus, which contains phytase and lactic acid, wherein the phytase can degrade phytate in the cereal raw materials and shorten the fermentation time without affecting the pH value of the frozen dough. The phytase indirectly acts on α-amylase to increase the volume of baked food such as bread and improve the internal structure. The main function of phytase is to hydrolyze the phosphate groups in phytic acid and its similar compounds, and release minerals such as calcium and iron, so that they can be used by the body, thereby promoting the absorption of minerals and maintaining normal growth and development and physiological functions. 2. Although the phytase in the Rhizopus fermentation product of the present invention cannot completely degrade the phytate in the frozen grain dough, it can significantly reduce the phytate content in the dough; the Rhizopus fermentation product also contains lactic acid, and the accumulation of lactic acid puts the system in an acidic environment, and the phosphate group of phytic acid loses part of its negative charge, resulting in a weakening of its ability to bind to metal ions, increasing the solubility of phytate, and promoting the decomposition of phytic acid and metal ion complexes, thereby improving the utilization rate of minerals; 3. The accumulation of lactic acid in the root mold fermentation product of the present invention leads to a decrease in the pH value of the system, inhibits the growth of yeast cells, thereby reducing the production of carbon dioxide, resulting in a reduction in the volume of baked foods such as bread and a compact tissue structure; the reduction in yeast activity slows down the fermentation speed of the dough, resulting in insufficient fermentation during bread making, affecting the fluffiness and flavor of the bread; an appropriate amount of zinc lactate can chelate lactic acid in the system, reduce the inhibitory effect of lactic acid on yeast, increase the specific volume of the bread, and improve the quality; at the same time, yeast cells also absorb zinc during the proliferation process and combine it in the organic components of the cells, thereby improving the bioavailability of zinc. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 This is a sensory radar chart of the low-phytic acid cereal bread prepared in Example 8 and Comparative Examples 1-4. DETAILED DESCRIPTION The present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are explanations of the present invention and the present invention is not limited to the following embodiments: Example 1 Preparation of Rhizopus fermentation products: S1. Activate Rhizopus in PDA medium and prepare seed liquid medium (glucose 80 g / L, (NH4)2SO4 4 g / L, KH2PO4 0.3 g / L, FeSO4·7H2O 0.44 g / L, MgSO4·7H2O 0.25 g / L), sterilize at 115°C for 20 min; S2. Inoculate a single colony of Rhizopus after activation into the seed liquid culture medium, and culture on a shaker at 30°C and 200 rpm for 1 day to obtain the seed liquid; S3. Inoculate the seed liquid into fermentation medium (glucose 160g / L, (NH4)2SO46g / L, KH2PO40.15g / L, FeSO4·7H2O 0.22g / L, MgSO4·7H2O 0.25g / L, NaH2PO40.15g / L, CaCO380g / L) with an inoculation amount of 5%. Culture on a shaker at 30°C and 180rpm for 2 days, filter the filtrate, sterilize, and dry to obtain the Rhizopus fermentation product. Example 2 Preparation of Rhizopus fermentation products: S1. Activate Rhizopus in PDA medium and prepare seed liquid medium (glucose 80 g / L, (NH4)2SO4 4 g / L, KH2PO4 0.3 g / L, FeSO4·7H2O 0.44 g / L, MgSO4·7H2O 0.25 g / L), sterilize at 115°C for 20 min; S2. Inoculate a single colony of Rhizopus after activation into the seed liquid culture medium, and culture on a shaker at 30°C and 200 rpm for 1 day to obtain the seed liquid; S3. Inoculate the seed liquid into fermentation medium (glucose 160g / L, (NH4)2SO46g / L, KH2PO40.15g / L, FeSO4·7H2O 0.22g / L, MgSO4·7H2O 0.25g / L, NaH2PO40.15g / L, CaCO380g / L) with an inoculation amount of 6%. Culture on a shaker at 28°C and 200rpm for 2 days, filter the filtrate, sterilize, and dry to obtain the Rhizopus fermentation product. Example 3 Preparation of Rhizopus fermentation products: S1. Activate Rhizopus in PDA medium and prepare seed liquid medium (glucose 80 g / L, (NH4)2SO4 4 g / L, KH2PO4 0.3 g / L, FeSO4·7H2O 0.44 g / L, MgSO4·7H2O 0.25 g / L), sterilize at 121°C for 15 min; S2. Inoculate a single colony of Rhizopus after activation into the seed liquid culture medium, and culture on a shaker at 35°C and 180 rpm for 2 days to obtain the seed liquid; S3. Inoculate the seed liquid into fermentation medium (glucose 160g / L, (NH4)2SO46g / L, KH2PO40.15g / L, FeSO4·7H2O 0.22g / L, MgSO4·7H2O 0.25g / L, NaH2PO40.15g / L, CaCO380g / L) with an inoculation amount of 8%. Culture on a shaker at 30°C and 190rpm for 3 days, filter the filtrate, sterilize, and dry to obtain the Rhizopus fermentation product. Example 4 Preparation of Rhizopus fermentation products: S1. Activate Rhizopus in PDA medium and prepare seed liquid medium (glucose 80 g / L, (NH4)2SO4 4 g / L, KH2PO4 0.3 g / L, FeSO4·7H2O 0.44 g / L, MgSO4·7H2O 0.25 g / L), sterilize at 121°C for 15 min; S2. Inoculate a single colony of Rhizopus after activation into the seed liquid culture medium, and culture on a shaker at 35°C and 190 rpm for 2 days to obtain the seed liquid; S3. Inoculate the seed liquid into fermentation medium (glucose 160g / L, (NH4)2SO46g / L, KH2PO40.15g / L, FeSO4·7H2O 0.22g / L, MgSO4·7H2O 0.25g / L, NaH2PO40.15g / L, CaCO380g / L) with an inoculation amount of 10%. Culture on a shaker at 32°C and 180rpm for 3 days, filter the filtrate, sterilize, and dry to obtain the Rhizopus fermentation product. Phytase activity: Phosphorus was measured using the microcolorimetric method of Taussky and Shoor and Harland, and then the enzyme activity was calculated based on the phosphorus content; Lactic acid production: The lactic acid production was determined by the EDTA calcium determination method. 1-2 mL of the filtrate was dripped into a conical flask containing 100 mL of distilled water, 10 mL of 1M NaOH solution and 1-2 drops of calcium indicator were added, and titrated with 0.05 mol / L EDTA solution. The end point was when the solution changed from purple-red to pure blue. Lactic acid production (g / L) = 9 × V1 / V2 In the formula, V1 is the milliliter of EDTA solution used for titration endpoint; V2 is the milliliter of fermentation liquid absorbed. Table 1 Determination of phytase activity and lactic acid production in the Rhizopus fermentation products prepared in Examples 1-4 Phytase activity (U) Lactic acid production (g / L) Example 1 3355 60.3 Example 2 3460 61.5 Example 3 3286 59.4 Example 4 3380 61.2 As shown in Table 1, the phytase activity of the Rhizopus fermentation products prepared in Examples 1-4 was 3286-3460 U, and the lactic acid yield was 59.4-61.5 g / L. Therefore, the Rhizopus fermentation product prepared in Example 2 was selected for the subsequent preparation of cereal bread. Example 5 A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: 100 kg of wheat flour, 70 kg of rye flour, 30 kg of buckwheat flour, 8 kg of white sugar, 2 kg of yeast, 0.03 kg of zinc lactate and 8 kg of Rhizopus fermentation product are mixed and stirred, and 200 kg of water is added to form a fresh dough; Step 2: Place the fresh dough under 20% RH and 140°C conditions for moist heat treatment for 5 minutes, cut into small pieces of dough of 60 g, put into plastic wrap, seal, and quick-freeze in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C, and freeze to obtain low-phytic acid grain frozen dough. Example 6 A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: 100 kg of wheat flour, 72 kg of rye flour, 32 kg of buckwheat flour, 8 kg of white sugar, 2 kg of yeast, 0.04 kg of zinc lactate and 8 kg of Rhizopus fermentation product were mixed and stirred, and 220 kg of water were added to form a fresh dough; Step 2: Place the fresh dough under 20% RH and 140°C conditions for moist heat treatment for 6 minutes, cut into small pieces of dough of 60 g, put into plastic wrap, seal, and quick-freeze in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C, and freeze to obtain low-phytic acid grain frozen dough. Example 7 A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: 110 kg of wheat flour, 74 kg of rye flour, 36 kg of buckwheat flour, 9 kg of white sugar, 2 kg of yeast, 0.03 kg of zinc lactate and 9 kg of Rhizopus fermentation product were mixed and stirred, and 240 kg of water was added to form a fresh dough; Step 2: Place the fresh dough under 20% RH and 140°C conditions for moist heat treatment for 6 minutes, cut into small pieces of dough of 60 g, put into plastic wrap, seal, and quick-freeze in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C, and freeze to obtain low-phytic acid grain frozen dough. Example 8 A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: 120 kg of wheat flour, 76 kg of rye flour, 38 kg of buckwheat flour, 9 kg of white sugar, 2 kg of yeast, 0.04 kg of zinc lactate and 10 kg of Rhizopus fermentation product were mixed and stirred, and 250 kg of water were added to form a fresh dough; Step 2: Place the fresh dough under 25% RH and 140°C conditions for moist heat treatment for 8 minutes, cut into small pieces of dough of 70 g, put into plastic wrap, seal, and quick-freeze in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C, and freeze to obtain low-phytic acid grain frozen dough. Example 9 A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: 130 kg of wheat flour, 78 kg of rye flour, 40 kg of buckwheat flour, 8 kg of white sugar, 3 kg of yeast, 0.05 kg of zinc lactate and 10 kg of Rhizopus fermentation product were mixed and stirred, and 260 kg of water was added to form a fresh dough; Step 2: Place the fresh dough under 25% RH and 145°C conditions for moist heat treatment for 8 minutes, cut into small pieces of dough of 80 g, put into plastic wrap, seal, and quick-freeze in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C, and freeze to obtain low-phytic acid grain frozen dough. Example 10 A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: 140 kg of wheat flour, 80 kg of rye flour, 42 kg of buckwheat flour, 9 kg of white sugar, 3 kg of yeast, 0.05 kg of zinc lactate and 10 kg of Rhizopus fermentation product were mixed and stirred, and 280 kg of water was added to form a fresh dough; Step 2: Place the fresh dough under 25% RH and 140°C conditions for moist heat treatment for 8 minutes, cut it into small pieces of dough of 80 g, put it in plastic wrap, seal it, and quickly freeze it in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C. Frozen it to obtain low-phytic acid grain frozen dough. Embodiment 11 A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: 150 kg of wheat flour, 80 kg of rye flour, 48 kg of buckwheat flour, 10 kg of white sugar, 3 kg of yeast, 0.05 kg of zinc lactate and 9 kg of Rhizopus fermentation product were mixed and stirred, and 300 kg of water was added to form a fresh dough; Step 2: subject the fresh dough to a wet heat treatment at 20% RH and 140°C for 10 min, cut the dough into small pieces of 60 g, wrap them in plastic wrap, seal them, and quickly freeze them in a -40°C refrigerator for 90 min until the center temperature of the dough reaches -18°C. Frozen dough is obtained to obtain low-phytic acid grain frozen dough. Example 12 A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: 150 kg of wheat flour, 80 kg of rye flour, 50 kg of buckwheat flour, 10 kg of white sugar, 3 kg of yeast, 0.05 kg of zinc lactate and 9 kg of Rhizopus fermentation product are mixed and stirred, and 300 kg of water are added to form a fresh dough; Step 2: subject the fresh dough to a wet heat treatment at 20% RH and 145°C for 10 min, cut the dough into small pieces of 80 g, wrap them in plastic wrap, seal them, and quickly freeze them in a -40°C refrigerator for 90 min until the center temperature of the dough reaches -18°C. Frozen the dough can yield low-phytic acid grain frozen dough. Comparative Example 1 The difference between this comparative example and Example 8 is that zinc lactate is not added, specifically as follows: A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: 120 kg of wheat flour, 76 kg of rye flour, 38 kg of buckwheat flour, 9 kg of white sugar, 2 kg of yeast and 10 kg of Rhizopus fermentation product were mixed and stirred, and 250 kg of water were added to form a fresh dough; Step 2: Place the fresh dough under 25% RH and 140°C conditions for moist heat treatment for 8 minutes, cut into small pieces of dough of 70 g, put into plastic wrap, seal, and quick-freeze in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C, and freeze to obtain low-phytic acid grain frozen dough. Comparative Example 2 The difference between this comparative example and Example 8 is that no Rhizopus fermentation product is added, which is as follows: A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: Mix 120kg wheat flour, 76kg rye flour, 38kg buckwheat flour, 9kg white sugar, 2kg yeast and 0.04kg zinc lactate, add 250kg water and knead into fresh dough; Step 2: Place the fresh dough under 25% RH and 140°C conditions for moist heat treatment for 8 minutes, cut into small pieces of dough of 70 g, put into plastic wrap, seal, and quick-freeze in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C, and freeze to obtain low-phytic acid grain frozen dough. Comparative Example 3 The difference between this comparative example and Example 8 is that no Rhizopus fermentation product and zinc lactate were added, specifically as follows: A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: Mix 120kg wheat flour, 76kg rye flour, 38kg buckwheat flour, 9kg white sugar, and 2kg yeast, add 250kg water, and knead into fresh dough; Step 2: Place the fresh dough under 25% RH and 140°C conditions for moist heat treatment for 8 minutes, cut into small pieces of dough of 70 g, put into plastic wrap, seal, and quick-freeze in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C, and freeze to obtain low-phytic acid grain frozen dough. Comparative Example 4 The difference between this comparative example and Example 8 is that no Rhizopus fermentation product is added, but phytase is directly added, as follows: A method for preparing low-phytic acid cereal frozen dough comprises the following steps: Step 1: Mix 120kg wheat flour, 76kg rye flour, 38kg buckwheat flour, 9kg white sugar, 2kg yeast, 0.04kg zinc lactate and 0.19kg phytase, add 250kg water, and knead into fresh dough; Step 2: Place the fresh dough under 25% RH and 140°C conditions for moist heat treatment for 8 minutes, cut into small pieces of dough of 70 g, put into plastic wrap, seal, and quick-freeze in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C, and freeze to obtain low-phytic acid grain frozen dough. Performance Testing: (1) Yeast fermentation capacity The yeast fermentation capacity was determined by the drainage method, referring to the method used by Zhou Honglu et al. in studying the fermentation characteristics of different yeasts on frozen dough, and the calculation was performed according to the following formula: Fermentation power F = V2-V1 Among them, F is the fermentation capacity, mL; V2 is the sum of the displacement in 3 hours, mL; V1 is the sum of the displacement in the first hour, mL. Table 2 Yeast fermentation ability of low phytic acid cereal frozen dough prepared in each embodiment and comparative example Yeast fermentation capacity (mL) Yeast fermentation capacity (mL) Example 5 815 Embodiment 11 813 Example 6 819 Example 12 813 Example 7 821 Comparative Example 1 726 Example 8 829 Comparative Example 2 794 Example 9 804 Comparative Example 3 801 Example 10 810 Comparative Example 4 805 As can be seen from Table 2, the yeast fermentation power of the low-phytic acid cereal frozen dough prepared in Examples 5-12 is 804-829 mL, while in Comparative Example 1, zinc lactate is not added, and the accumulation of lactic acid in the Rhizopus fermentation product hinders the growth and fermentation of yeast, resulting in a lower yeast fermentation power of the prepared frozen dough, which affects the fluffiness of subsequent baked foods and reduces the overall quality. The low-phytic acid cereal frozen dough prepared in the above Examples 5-12 and Comparative Examples 1-4 was thawed and formed into a bread shape, and placed at 36° C. and 70% RH for 30 minutes to obtain a proofed dough, and then the proofed dough was baked at 180° C. for 12 minutes and cooled to obtain low-phytic acid cereal bread. The prepared low-phytic acid cereal bread was tested for the following indicators: (2) Phytic acid content Weigh 0.5g bread sample, place in a 50mL centrifuge tube, add 30mL 0.5mol / L HCl solution, shake and extract at room temperature at 150r / min for 3h; centrifuge at 5000r / min for 30min, discard the precipitate, and take the supernatant; mix 1mL supernatant (blank group replaced by 1mL HCl solution) and 2mL 0.02% NH4Fe(SO4)2 solution and boil water for 30min, immediately cool in ice bath, centrifuge at 6000r / min for 30min and take the supernatant; mix 2mL supernatant with 3mL 1% bipyridine for color reaction, and measure the absorbance at 519nm wavelength. Standard curve preparation: dissolve phytic acid standard with HCl solution to make its mass concentration of 1.0mg / mL, and then dilute to 0, 0.04, 0.08, 0.12, 0.16mg / L and 0.2mg / L phytic acid solution, which are used as standard solution to draw standard curve. Table 3 Phytic acid content of low-phytic acid cereal bread prepared in each embodiment and comparative example As shown in Table 3, the phytic acid content in the low-phytic acid bread prepared in Examples 5-12 is 0.95-1.24 mg / g, the phytic acid content in the bread prepared in Comparative Example 3 without adding root mold fermentation product and zinc lactate is 1.80 mg / g, and Example 8 is reduced by 47% compared with Comparative Example 3; Comparative Example 2 does not add root mold fermentation product, and cannot produce phytase and lactic acid, so the phytic acid content in the prepared bread is also high, which is 1.71 mg / g; Comparative Example 1 does not add zinc lactate, which has little effect on phytic acid; Comparative Example 4 directly adds phytase, and the phytic acid content is slightly increased compared with the embodiment. Therefore, it can be seen that adding root mold fermentation product and zinc lactate to the cereal bread formula can greatly reduce the phytic acid content and promote mineral absorption. (3) Bread volume The volume of bread was determined by the rapeseed displacement method. The specific volume of bread was calculated as follows: Table 4 Specific volume of low phytic acid cereal bread prepared in each embodiment and comparative example Specific volume (mL / g) Specific volume (mL / g) Example 5 5.35 Embodiment 11 5.43 Example 6 5.69 Example 12 5.37 Example 7 5.31 Comparative Example 1 3.21 Example 8 5.75 Comparative Example 2 5.12 Example 9 4.97 Comparative Example 3 5.24 Example 10 5.14 Comparative Example 4 5.33 As can be seen from Table 4, the specific volume of the low-phytic acid cereal bread prepared in Examples 5-12 is between 4.97 and 5.75. The larger the specific volume, the fluffier the bread is. However, the specific volume of the cereal bread prepared in Comparative Example 1 without adding zinc lactate is 3.21, and the bread is firmer. It can be seen that the addition of zinc lactate can hinder the inhibitory effect of lactic acid on yeast in the system, thereby increasing the fermentation volume of the bread and the specific volume. (4) Bread texture characteristics Use a bread slicer to cut the bread into slices with a thickness of 10 mm, stack the two slices in the middle, and use a texture analyzer for measurement. Parameters: Probe model is P / 36, pre-test speed is 1.0 mm / s, test speed is 3.0 mm / s, post-test speed is 3.0 mm / s, compression degree is 50%, induction force is 5g, and the interval between two compressions is 1 second. Table 5 Texture characteristics of low phytic acid cereal bread prepared in each embodiment and comparative example As can be seen from Table 5, the low-phytic acid cereal breads prepared in Examples 5-12 have good overall quality in terms of hardness, elasticity and chewiness. However, in Comparative Example 1, the low-phytic acid cereal bread prepared without adding zinc lactate is unable to chelate the lactic acid in the system, causing lactic acid to inhibit the growth and fermentation of yeast. The hardness of the prepared bread increases, the elasticity decreases, the chewiness is also the worst, and the overall quality of the bread decreases. (5) Sensory evaluation of bread The sensory evaluation was conducted using the 9-point preference method, and 20 trained personnel (10 females and 10 males) scored the appearance, internal structure, mouthfeel, softness and overall acceptability of the low-phytic acid cereal breads prepared in Example 8 and Comparative Examples 1-4. Depend on Figure 1 It can be seen that the overall acceptance of the low-phytic acid cereal bread prepared in Example 8 is the highest, and the overall acceptance of the bread prepared in Comparative Example 1 is the lowest. The addition of zinc lactate can chelate the lactic acid in the fermentation product of Rhizopus, reduce the inhibition of lactic acid on yeast growth and fermentation, thereby increasing the fermentation volume of the bread, making the internal structure fluffy, and the softness correspondingly improved, and finally improving the quality of the bread. The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A low-phytic acid cereal frozen dough, characterized in that: The invention comprises the following components: by weight, 100-150 parts of wheat flour, 70-80 parts of rye flour, 30-50 parts of buckwheat flour, 200-300 parts of water, 8-10 parts of white sugar, 2-3 parts of yeast, 0.03-0.05 parts of zinc lactate and 8-10 parts of root mold fermentation product.

2. The low-phytic acid cereal frozen dough according to claim 1, characterized in that: The preparation steps of the root mold fermentation product are specifically as follows: S1. Activate Rhizopus in PDA medium and prepare seed liquid medium, sterilize at 115-121°C for 15-20min; S2. Inoculate a single colony of Rhizopus after activation into the seed liquid culture medium, and culture on a shaker at 30-35°C and 180-200rpm for 1-2 days to obtain a seed liquid; S3. Inoculate the seed liquid into the fermentation medium, culture on a shaker at 28-32°C and 180-200 rpm for 2-3 days, filter the filtrate, sterilize, and dry to obtain the Rhizopus fermentation product.

3. A low-phytic acid cereal frozen dough according to claim 2, characterized in that: The components of the seed liquid culture medium in step S1 are: glucose 80 g / L, (NH4)2SO4 4 g / L, KH2PO4 0.3 g / L, FeSO4·7H2O 0.44 g / L, and MgSO4·7H2O 0.25 g / L.

4. The low-phytic acid cereal frozen dough according to claim 2, characterized in that: The seed liquid inoculation amount in step S3 is 5-10%; the fermentation medium components are glucose 160g / L, (NH4)2SO46g / L, KH2PO40.15g / L, FeSO4·7H2O 0.22g / L, MgSO4·7H2O 0.25g / L, NaH2PO40.15g / L, and CaCO380g / L.

5. The method for preparing low-phytic acid cereal frozen dough according to claim 1, characterized in that: The following steps are involved: Step 1: Mix wheat flour, rye flour, buckwheat flour, white sugar, dry yeast, zinc lactate and Rhizopus fermentation product, add water, and knead into fresh dough; Step 2: subject the fresh dough to a wet heat treatment at 20-25% RH and 140-145°C for 5-10 minutes, cut the dough into small pieces of 60-80 g, wrap them in plastic wrap, seal them, and quickly freeze them in a -40°C refrigerator for 90 minutes until the center temperature of the dough reaches -18°C. Frozen the dough can obtain low-phytic acid grain frozen dough.

6. Use of the low-phytic acid cereal frozen dough according to any one of claims 1 to 4 in baked goods.

7. The use according to claim 6, characterized in that: The baked food includes bread and cake.

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