A method for improving the quality of millet steamed cake

Abstract

The application discloses a millet steamed cake quality improvement method and belongs to the technical field of food processing, and comprises the following steps: S1, millet powder preparation: after coarse grinding, millet is sieved through 60-90 meshes to obtain sieved millet powder; S2, millet starch extraction and purification: the sieved millet powder is soaked in a sodium hydroxide solution at room temperature and centrifuged to remove impurities, and the precipitation and hydrochloric acid pH adjustment are repeated until there is no yellow layer, so that primary-extracted millet starch is obtained; after ethanol washing, the millet starch is dried to obtain the millet starch; S3, preparation of millet starch-phenolic acid compound: accurately weigh 3-6 g of phenolic acid and millet starch, place them in an RVA aluminum tank, add water to a total weight of 25-30 g, and then process the starch paste in an RVA instrument according to a program to obtain a starch paste; subsequently, the starch paste is frozen, freeze-dried, ground and filtered to obtain the millet starch-phenolic acid compound. The millet steamed cake quality improvement method solves the problem that millet cannot form a good network structure due to the absence of gluten protein in the prior art. The millet steamed cake has the advantages of good taste, good appearance and high nutritional value.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, specifically to a method for improving the quality of millet steamed cake. Background Technology

[0002] Millet, a traditional grain crop with a long history, demonstrates remarkable environmental adaptability, especially in arid and semi-arid regions where it has become an indispensable staple food source in areas with scarce water resources. Millet's main components include abundant starch, high-quality protein, lipids, and small amounts of free sugars and non-starch polysaccharides, which together form a balanced nutritional base. More notably, millet contains high levels of antioxidants, particularly phenolic compounds. These naturally endowed active ingredients exhibit positive effects on maintaining cardiovascular health. Phenolic compounds not only act as bioactive molecules, contributing to the fight against oxidative stress and the prevention of chronic diseases, but also influence the retrogradation process of starch and its digestible properties.

[0003] Steamed sponge cake, made through fermentation and steaming, has a honeycomb-like structure, a soft texture, and a unique flavor. It is tender, sweet but not cloying, and glutinous but not sticky, making it a popular traditional Chinese fermented food, often eaten as a staple. Most commercially available steamed sponge cakes use wheat flour or rice flour as the main ingredient. In recent years, with improved living standards and increased health awareness, people have placed higher demands on the nutritional value and flavor of food. Because millet lacks gluten protein and cannot form a good network structure, many researchers have replaced a small portion of the wheat flour in steamed sponge cakes with millet flour. However, wheat flour and rice flour still constitute a large proportion, failing to fully utilize the nutritional value and unique flavor of millet. Currently, there are few research reports on making high-content millet steamed sponge cakes, and a millet steamed sponge cake that simultaneously possesses good taste, nutrition, and appearance is lacking.

[0004] Therefore, there is an urgent need for a method to improve the quality of millet steamed cake, which involves constructing a gluten-like network structure to improve the quality of the steamed cake after replacing part of the wheat flour with millet. Summary of the Invention

[0005] Therefore, the present invention provides a method for improving the quality of millet steamed cake, in order to solve the problem in the prior art that millet cannot form a good network structure due to the absence of gluten protein.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] According to a first aspect of the present invention, a method for improving the quality of millet cake is provided, comprising the following steps:

[0008] S1. Preparation of millet flour: After coarsely grinding millet, pass it through a 60-90 mesh to obtain sieved millet flour;

[0009] S2. Extraction and purification of millet starch: At room temperature, sieved millet flour is soaked in sodium hydroxide solution and centrifuged to remove impurities. The precipitation is repeated, and the pH is adjusted with hydrochloric acid until no yellow layer is obtained to obtain the initial millet starch. After washing with ethanol, it is dried to obtain millet starch.

[0010] S3. Preparation of millet starch-phenolic acid complex: Accurately weigh 3-6g of phenolic acid and millet starch into an RVA aluminum can, add water to 25-30g of total weight, process in an RVA instrument according to the program to obtain starch paste, and then freeze, freeze dry, grind and filter the starch paste to obtain millet starch-phenolic acid complex.

[0011] S4. Preparation of steamed cake batter: Weigh out wheat flour, millet flour, millet starch-phenolic acid complex, sugar, yeast, oil, and water in quantitative amounts, and mix them evenly;

[0012] S5. Fermentation treatment: Place the steamed cake batter in a constant temperature fermentation box for the first fermentation of 0.5-1.5 hours, stir to release gas, and then ferment for a second time of 0.5-2 hours;

[0013] S6. Steaming the millet cake: Place the fermented millet cake batter in a steamer and steam for 30 minutes to obtain the millet millet cake.

[0014] Furthermore, the concentration of the sodium hydroxide solution in S2 is 0.3% (w / v), and the ratio of the sodium hydroxide solution to the sieved millet flour is 1:3 (w / v).

[0015] Furthermore, in step S2, the sieved millet flour is soaked in sodium hydroxide solution for 12-18 hours.

[0016] Furthermore, the slurry in S2 is centrifuged at 3500-6500×g for 10-30 min.

[0017] Furthermore, the concentration of hydrochloric acid in S2 is 0.5-1.5M, and the pH of the starch suspension is adjusted to 7.0.

[0018] Furthermore, the amount of phenolic acid added in S3 accounts for 2.5% of the total powder mass.

[0019] Furthermore, in step S4, the mass ratio of wheat flour to millet flour is 3:2.

[0020] Furthermore, the amount of millet starch-phenolic acid complex added is 2.5-5.0% of the mass of the mixed powder.

[0021] Furthermore, after adding the millet starch-phenolic acid complex, the height of the steamed cake was 4.02-5.25 cm, the porosity was 37.36-48.31%, the hardness was 10.26-4.91 N, the elasticity was 8.95-10.50, the cohesiveness was 0.36-0.49, and the crystallinity was 7.65-6.02%.

[0022] The present invention has the following advantages:

[0023] 1. The improved method of this application is based on 60% wheat flour, blended with 40% millet flour, and utilizes a millet starch-phenolic acid complex to effectively improve the fluffiness, hardness, elasticity, and adhesiveness of millet steamed cake, reduce porosity, and enhance the viscoelasticity of the cake batter. Compared with traditional grains such as wheat and rice, millet is rich in high-quality protein, dietary fiber, phenolic substances, and minerals.

[0024] 2. The improved method of this application can effectively improve the edible quality of millet cake, which is conducive to expanding the scope and depth of millet processing and has broad market prospects. Attached Figure Description

[0025] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0026] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0027] Figure 1 The effect of the millet starch-phenolic acid complex provided by the present invention on the textural properties of millet steamed cake;

[0028] Figure 2 The effect of the millet starch-phenolic acid complex provided by the present invention on the microstructure of millet steamed cake;

[0029] Figure 3 XRD diffraction patterns of millet starch-phenolic acid complex, steamed cake powder, and steamed cake paste provided by the present invention;

[0030] Figure 4 The effect of the millet starch-phenolic acid complex provided by the present invention on the rheological properties of steamed rice cake paste. Detailed Implementation

[0031] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a method for improving the quality of millet cake, comprising the following steps:

[0033] S1. Preparation of millet flour: After coarsely grinding millet, pass it through a 60-90 mesh to obtain sieved millet flour; part of the sieved millet flour is reserved as a base flour for steamed cakes, and the other part is used to extract millet starch.

[0034] S2. Extraction and purification of millet starch: At room temperature, sieved millet flour is soaked in sodium hydroxide solution and centrifuged to remove impurities. The precipitation is repeated, and the pH is adjusted with hydrochloric acid until no yellow layer is obtained to obtain the initial millet starch. After washing with ethanol, it is dried to obtain millet starch.

[0035] S3. Preparation of millet starch-phenolic acid complex: Accurately weigh 3-6g of phenolic acid and millet starch into an RVA aluminum can, add water to 25-30g of total weight, process the starch paste in the RVA instrument according to the program, and then freeze, freeze dry, grind and filter the starch paste in a -80℃ refrigerator to obtain millet starch-phenolic acid complex.

[0036] S4. Preparation of steamed cake batter: Weigh out wheat flour, millet flour, millet starch-phenolic acid complex, sugar, yeast, oil, and water in quantitative amounts, and mix them evenly;

[0037] S5. Fermentation treatment: Place the steamed cake batter in a constant temperature fermentation box for the first fermentation of 0.5-1.5 hours, stir to release gas, and then ferment for a second time of 0.5-2 hours;

[0038] S6. Steaming the millet cake: Place the fermented millet cake batter in a steamer and steam for 30 minutes to obtain the millet cake.

[0039] Specifically, the concentration of sodium hydroxide solution in S2 is 0.3% (w / v), and the ratio of sodium hydroxide solution to sieved millet flour is 1:3 (w / v).

[0040] Specifically, the sieved millet flour in S2 is soaked in sodium hydroxide solution for 12-18 hours.

[0041] Specifically, the amount of phenolic acid added in S3 accounts for 2.5% of the total powder mass.

[0042] Specifically, in S4, the mass ratio of wheat flour to millet flour is 3:2.

[0043] Specifically, the amount of millet starch-phenolic acid complex added is 2.5-5.0% of the mixed powder mass.

[0044] The height of the steamed cake after adding millet starch-phenolic acid complex is 4.02-5.25 cm, the porosity is 37.36-48.31%, the hardness is 10.26-4.91 N, the elasticity is 8.95-10.50, the cohesiveness is 0.36-0.49, and the crystallinity is 7.65-6.02%.

[0045] Example 1

[0046] S1: Millet powder: After coarsely grinding the millet, pass it through an 80-mesh sieve. Reserve part of it to make the base powder for steamed cakes, and extract the millet starch from the other part.

[0047] S2: Extraction of millet starch: The obtained 80-mesh sieve powder was soaked in sodium hydroxide solution (0.3% w / v) at a ratio of 1:3 (w / v) for 18 h at room temperature; then, the slurry was centrifuged at 6500×g for 10 min to remove the supernatant and the upper yellow layer, and the precipitated crude starch was resuspended in distilled water; the pH of the starch suspension was adjusted to 7.0 with 1.0M hydrochloric acid, and the above steps were repeated twice until no upper yellow layer was present. The obtained starch was washed with ethanol and dried overnight.

[0048] S3: Preparation of millet starch-phenolic acid complex:

[0049] Accurately weigh 3.0g of caffeic acid and millet starch into an RVA aluminum can, add water to the can until the total weight is 25.0g, then put the weighed sample into the instrument and run it according to the set program; freeze the starch paste obtained from RVA in a -80℃ freezer and then transfer it to a freeze dryer for freeze drying; put the freeze-dried sample into a grinder for grinding and pass it through an 80-mesh sieve.

[0050] S4: Preparation of steamed cake batter: Add millet starch-caffeic acid complex to the mixed steamed cake flour (60 parts wheat flour and 40 parts millet flour) at a ratio of 2.5% and 5% respectively, and mix sugar, yeast, oil and water evenly in a certain proportion;

[0051] S5: Fermentation treatment: Put the mixed rice cake batter into a constant temperature fermentation box. After the first fermentation for 1.5 hours, take it out, stir to release the air, and then put it back into the fermentation box for a second fermentation for 0.5 hours.

[0052] S6: Steamed Cake: Place the fermented cake batter directly into a steam oven and steam at 100℃ for 30 minutes.

[0053] S7: The methods for determining the height, textural properties, microstructure, crystal form of the steamed cake paste and the steamed cake powder, and the rheological properties of the steamed cake paste are as follows:

[0054] (1) Determination of the height of the steamed cake: After steaming, let the steamed cake cool to room temperature, cut it in half, and measure the height of the cake at the middle position with a vernier caliper. Measure each sample 3 times and record the height value.

[0055] (2) Determination of the textural properties of steamed rice cake: After the steamed rice cake was cooled at room temperature for 1 hour, the middle part was cut into cubes with a volume of approximately 2.5cm × 2.5cm × 2.5cm. The samples were measured using a texture analyzer with a probe of 2.54cm in diameter. The probe speed was 2.0mm / s before measurement, 2.0mm / s during measurement, and 2.0mm / s after measurement. The compression degree was set to 50%, and the compression cycle was repeated twice. The trigger force was 5g. To improve the reliability of the results, each sample was tested three times, and the average value was taken to represent its textural properties.

[0056] This analysis focused on six key indicators: hardness, elasticity, chewiness, cohesion, adhesion, and stickiness. These parameters comprehensively reflect the texture and physical properties of the steamed rice cake. The experimental results are as follows: Figure 1 The samples are presented in a visually intuitive format for comparison. The sample series used in this textural property determination covered different treatment types, including: Control: regular steamed cake without any special complex added; PMS: steamed cake with added gelatinized millet starch, designed to observe the effect of starch treatment on texture; CMS: steamed cake containing millet starch-caffeic acid complex, exploring the modifying effect of caffeic acid on the texture of steamed cake; CMS2.5 and CMS5.0: steamed cakes with added 2.5% and 5.0% millet starch-caffeic acid complex, respectively, to evaluate the effect of different addition amounts on textural properties.

[0057] (3) Determination of the network structure of steamed rice cake: After the steamed rice cake was cooled at room temperature for 1 hour, a cross-sectional layer of the center of the steamed rice cake was uniformly cut out, and the cross-sectional structure of the steamed rice cake was scanned. The honeycomb structure of the steamed rice cake was analyzed and the porosity was calculated using ImageJ software. Porosity is the ratio of the total surface area of ​​the pores to the area of ​​the image taken.

[0058] Determination of the microstructure of steamed rice cake: such as Figure 2 As shown, the freeze-dried rice cake paste sample was fixed to the sample holder using conductive double-sided tape and observed using a Phenom XL scanning electron microscope (Phenom GmbH, Netherlands) at an accelerating voltage of 15 kV. The sample was sputtered with 20 nm gold using a Denton Vacuum DESKIV instrument to enhance conductivity and ensure effective transmission of electronic signals.

[0059] The samples involved in this embodiment include: a basic control group of steamed rice cake paste (FMC) without any added complex, steamed rice cake paste (FMC-PMS) with added gelatinized millet starch, steamed rice cake paste (FMC-CMS) containing a millet starch-caffeic acid complex, and steamed rice cake paste (FMC-CA) with directly added caffeic acid. Furthermore, to explore the effect of the added amount in more detail, samples at different concentration levels were prepared. For example, FMC-CA2.5, FMC-PMS2.5, and FMC-CMS2.5 represent samples with 2.5% of the corresponding ingredient added, while FMC-CA5.0, FMC-PMS5.0, and FMC-CMS5.0 represent samples with 5.0% added.

[0060] (4) Crystal form determination of millet starch-phenolic acid complex: In this embodiment, X-ray diffraction was used to accurately depict the internal structural features of the millet starch-phenolic acid complex during crystal form analysis. The experimental conditions were set to 40 kV voltage and 40 mA current, with a scan range from 4° to 40° (2θ), covering the key diffraction angles and helping to reveal crystal structure information. The scan rate was 2° per minute to ensure the accuracy of data acquisition, while the step size was set to 0.02° to increase the resolution of the results. To eliminate the interference of moisture on the test results and ensure measurement accuracy, all samples were placed in a desiccator at room temperature overnight for equilibration before XRD analysis.

[0061] This test covered multiple samples, including raw millet starch MS, gelatinized millet starch PMS, millet starch-caffeic acid complex CMS, pure caffeic acid CA, and various steamed cake samples as control groups: basic steamed cake paste FMC without any complex added, steamed cake FMC-PMS with gelatinized millet starch added, steamed cake FMC-CMS with millet starch-caffeic acid complex added, and millet steamed cake FMC-CA with caffeic acid added alone;

[0062] To investigate the effects of different addition amounts in more detail, samples with different concentration gradients were prepared: FMC-PMS2.5, FMC-CMS2.5, and FMC-CA2.5: 2.5% of gelatinized starch, caffeic acid complex, and caffeic acid were added, respectively; FMC-PMS5.0, FMC-CMS5.0, and FMC-CA5.0: 5.0% of gelatinized starch, caffeic acid complex, and caffeic acid were added, respectively. See details. Figure 3 The data were processed using Origin 64 software to calculate the relative crystallinity (RC, %) of each sample, thereby quantifying the degree of influence of different treatments on starch structure.

[0063] (5) Determination of rheological properties of steamed cake batter: Frequency, creep, strain, and temperature scan measurements were all performed using a rheometer. A parallel metal plate with a diameter of 40 mm was selected, and the test gap was 1 mm. The specific operating method is as follows: The sample was prepared fresh for use. 1.5 mL of the batter prepared by the dough mixer was drawn up and quickly transferred to the plate. Excess sample was removed, and silicone oil was applied around the sample to prevent it from drying out during the test.

[0064] Strain scanning parameters: Strain scanning tests (0.01%-200%) were performed at a constant frequency (1Hz) and temperature (25℃), and the storage modulus (G′), loss modulus (G″), and loss tangent (tanδ, G″ / G′) were recorded.

[0065] Frequency scanning parameters: Storage modulus (G′, Pa) and loss modulus (G″, Pa) were measured within the range of 0.1-50 Hz at constant strain (0.1%, determined in the linear viscoelastic region) and temperature (25 °C). Creep scanning parameters: Equilibration at 25 °C for 60 s. During the test, a constant stress (4 Pa) was applied to the batter for 3 min. Then, the stress was removed, and the batter was allowed 5 min to recover the elastic portion of the deformation. Shear strain over time was recorded. Temperature scanning parameters: Equilibration at 25 °C for 30 s, then the sample was heated from 25 °C to 100 °C at a heating rate of 25 °C / min. The sample was held at 100 °C for 10 min, and the viscosity was recorded as a function of temperature. Figure 4 As shown.

[0066] This test covered a series of steamed cake batter samples, including: a control group (FMC), i.e., basic steamed cake batter without any additional additives; steamed cake batter with added gelatinized millet starch (FMC-PMS); steamed cake batter with added millet starch-caffeic acid complex (FMC-CMS); and steamed cake batter with added caffeic acid (FMC-CA). To further refine the analysis of the effect of additive concentration, samples with different concentrations were also prepared: FMC-CA2.5, FMC-PMS2.5, and FMC-CMS2.5, representing the addition of 2.5% of the corresponding ingredient; and FMC-CA5.0, FMC-PMS5.0, and FMC-CMS5.0, representing the addition of 5.0% of the corresponding ingredient. Through this series of rheological tests and sample analysis, we can systematically evaluate how different treatments and concentrations of additives modulate the rheological properties of steamed cake batter, providing a scientific basis for optimizing the texture and processing performance of steamed cakes.

[0067] The results of this embodiment are as follows: the millet starch-caffeic acid complex significantly improved the baking and textural quality of millet steamed cake. Compared with the steamed cake without the millet starch-caffeic acid complex, the height increased by 25.87%, while the hardness, adhesiveness, and cohesiveness decreased by 22.32%, 8.53%, and 7.69%, respectively. Elasticity, chewiness, and cohesiveness increased by 20.67%, 10.08%, and 19.44%, respectively, and porosity increased by 6.42%. The relative crystallinity of the steamed cake powder decreased by 19.61%. In terms of rheological properties, the G′ and G″ values ​​of the paste with the complex were both higher than those of the control group. Overall, the millet starch-phenolic acid complex can improve the gas-holding capacity of the steamed cake paste and the texture of the steamed cake to a certain extent.

[0068] Example 2.

[0069] S1: Millet powder: After coarsely grinding the millet, pass it through an 80-mesh sieve. Reserve part of it to make the base powder for steamed cakes, and extract the millet starch from the other part.

[0070] S2: Extraction of millet starch: The obtained 80-mesh sieve powder was soaked in sodium hydroxide solution (0.3% w / v) at a ratio of 1:3 for 18 hours at room temperature. Afterwards, the slurry was centrifuged at 6500×g for 10 minutes to remove the supernatant and the upper yellow layer, precipitating the crude starch. The crude starch was resuspended in distilled water. The pH of the starch suspension was adjusted to 7.0 with 1.0M hydrochloric acid, and the above steps were repeated twice until no upper yellow layer remained. The obtained starch was washed with ethanol and dried overnight.

[0071] S3: Preparation of millet starch-phenolic acid complex: Accurately weigh 3.0g of gallic acid and millet starch into an RVA aluminum can, add water to the aluminum can to a total weight of 25.0g, put the weighed sample into the instrument and run according to the set program; freeze the starch paste obtained from RVA in a -80℃ freezer and then transfer it to a freeze dryer for freeze drying. Put the freeze-dried sample into a grinder for grinding and pass it through an 80-mesh sieve.

[0072] S4: Preparation of steamed cake batter: Add millet starch-gallic acid complex to the mixed steamed cake flour (60 parts wheat flour and 40 parts millet flour) at a ratio of 2.5% and 5% respectively, and mix sugar, yeast, oil and water evenly in a certain proportion;

[0073] S5: Fermentation treatment: Put the mixed rice cake batter into a constant temperature fermentation box. After the first fermentation for 1.5 hours, take it out, stir to release the air, and then put it back into the fermentation box for a second fermentation for 0.5 hours.

[0074] S6: Processing millet cake: Place the fermented cake batter directly into a steam oven and steam at 100℃ for 30 minutes.

[0075] S7: The methods for determining the height, textural properties, microstructure, crystal form of the steamed cake paste and the steamed cake powder, and the rheological properties of the steamed cake paste are as follows:

[0076] (1) Determination of the height of the steamed cake: After steaming, let the steamed cake cool to room temperature, cut it in half, and measure the height of the cake at the middle position with a vernier caliper. Measure each sample 3 times and record the height value.

[0077] (2) Determination of the textural properties of steamed rice cake: After cooling at room temperature for 1 hour, the middle part of the steamed rice cake was cut into cubes with a volume of approximately 2.5cm × 2.5cm × 2.5cm. The samples were measured using a texture analyzer with a probe of 2.54cm in diameter. The probe speed was 2.0mm / s before measurement, 2.0mm / s during measurement, and 2.0mm / s after measurement. The compression degree was set to 50%, with 2 compression cycles and a trigger force of 5g. Each sample was measured 3 times, and the average value was taken. The textural properties focused on in this test mainly involved six dimensions: hardness, elasticity, chewiness, cohesion, adhesion, and stickiness. These indicators comprehensively reflect the physical properties and taste of the steamed rice cake. All analytical results are as follows: Figure 1 As shown, the effects of different treatments on the texture of steamed rice cake are compared visually.

[0078] The tested sample groups included: Control group: regular steamed cake without any added complex, serving as a baseline comparison; PMS: steamed cake with added gelatinized millet starch, to investigate the effect of starch treatment on the texture of the steamed cake; GMS: steamed cake with added millet starch-gallic acid complex, to observe the effect of gallic acid modification; GMS2.5 and GMS5.0: steamed cake with added 2.5% and 5.0% millet starch-gallic acid complex, respectively, to evaluate the effect of complex concentration on changes in texture properties.

[0079] (3) Determination of the network structure of steamed rice cake: After the steamed rice cake was cooled at room temperature for 1 hour, a cross-sectional layer of the center of the steamed rice cake was uniformly cut out, and the cross-sectional structure of the steamed rice cake was scanned. The honeycomb structure of the steamed rice cake was analyzed and the porosity was calculated using ImageJ software. Porosity is the ratio of the total surface area of ​​the pores to the area of ​​the image taken.

[0080] The results of this embodiment are as follows: the millet starch-gallic acid complex significantly improved the baking and textural quality of millet steamed cake. Compared with the steamed cake without the complex, the height of the steamed cake with 2.5% and 5% of the complex increased by 23.88% and 30.60%, respectively; the hardness decreased by 41.33% and 51.75%, respectively; the elasticity increased by 16.76% and 17.32%, respectively; the cohesiveness increased by 25.00% and 22.22%, respectively; and the porosity increased by 33.11% and 38.26%, respectively. Overall, the millet starch-gallic acid complex can improve the gas-holding capacity of the steamed cake batter and the texture of the steamed cake to a certain extent.

[0081] Example 3

[0082] S1: Millet powder: After coarsely grinding the millet, pass it through an 80-mesh sieve. Reserve part of it to make the base powder for steamed cakes, and extract the millet starch from the other part.

[0083] S2: Extraction of millet starch: The obtained 80-mesh sieve powder was soaked in sodium hydroxide solution (0.3% w / v) at a ratio of 1:3 for 18 hours at room temperature. Afterwards, the slurry was centrifuged at 6500×g for 10 minutes to remove the supernatant and the upper yellow layer, precipitating the crude starch. The crude starch was resuspended in distilled water. The pH of the starch suspension was adjusted to 7.0 with 1.0M hydrochloric acid, and the above steps were repeated twice until no upper yellow layer remained. The obtained starch was washed with ethanol and dried overnight.

[0084] S3: Preparation of millet starch-phenolic acid complex: Accurately weigh 3.0g of ferulic acid and millet starch into an RVA aluminum can, add water to the aluminum can to a total weight of 25.0g, put the weighed sample into the instrument and run according to the set program; freeze the starch paste obtained from RVA in a -80℃ freezer and then transfer it to a freeze dryer for freeze drying. Put the freeze-dried sample into a grinder for grinding and pass it through an 80-mesh sieve.

[0085] S4: Preparation of steamed cake batter: Add millet starch-ferulic acid complex to the mixed steamed cake flour (60 parts wheat flour and 40 parts millet flour) at a ratio of 2.5% and 5% respectively, and mix sugar, yeast, oil and water evenly in a certain proportion;

[0086] S5: Fermentation treatment: Put the mixed rice cake batter into a constant temperature fermentation box. After the first fermentation for 1.5 hours, take it out, stir to release the air, and then put it back into the fermentation box for a second fermentation for 0.5 hours.

[0087] S6: Processing millet cake: Place the fermented cake batter directly into a steam oven and steam at 100℃ for 30 minutes.

[0088] S7: The methods for determining the height, textural properties, microstructure, crystal form of the steamed cake paste and the steamed cake powder, and the rheological properties of the steamed cake paste are as follows:

[0089] (1) Determination of the height of the steamed cake: After steaming, let the steamed cake cool to room temperature, cut it in half, and measure the height of the cake at the middle position with a vernier caliper. Measure each sample 3 times and record the height value.

[0090] (2) Determination of the textural properties of steamed rice cake: After cooling at room temperature for 1 hour, the middle part of the steamed rice cake was cut into cubes with a volume of approximately 2.5cm × 2.5cm × 2.5cm. The samples were then measured using a texture analyzer with a probe of 2.54cm in diameter. The probe's pre-test speed was 2.0mm / s, mid-test speed was 2.0mm / s, and post-test speed was 2.0mm / s. The compression degree was set to 50%, with two compression cycles and a trigger force of 5g. To ensure data reliability, each sample was tested three times, and the average value was used as the official record. This test mainly focused on six key textural indicators: hardness, elasticity, chewiness, cohesion, adhesion, and adhesiveness. These parameters comprehensively reflect the physical properties and mouthfeel characteristics of the steamed rice cake. The test results for all samples are as follows: Figure 1 The presentation is intended to provide a direct comparison of the differences in the textural properties of steamed cake under different treatment conditions.

[0091] The sample components used in this texture determination included: Control group: steamed cake without any added complex, serving as a baseline reference. PMS: steamed cake with added gelatinized millet starch, to investigate the effect of gelatinization on texture properties. FMS: steamed cake with added millet starch-ferulic acid complex, to evaluate the modifying effect of the complex on the texture of the steamed cake. FMS2.5 and FMS5.0: steamed cakes containing 2.5% and 5.0% millet starch-ferulic acid complex, respectively, to analyze the fine-tuning effect of the amount of complex added on the texture properties of the steamed cake.

[0092] (3) Determination of the network structure of steamed rice cake: After the steamed rice cake was cooled at room temperature for 1 hour, a cross-sectional layer of the center of the steamed rice cake was uniformly cut out, and the cross-sectional structure of the steamed rice cake was scanned. The honeycomb structure of the steamed rice cake was analyzed and the porosity was calculated using ImageJ software. Porosity is the ratio of the total surface area of ​​the pores to the area of ​​the image taken.

[0093] The results of this embodiment are as follows: the millet starch-ferulic acid complex significantly improved the baking and textural quality of millet steamed cake. Compared with the steamed cake without the complex, the height of the steamed cake with 2.5% and 5% of the complex increased by 7.71% and 13.18%, respectively; the hardness decreased by 52.14% and 35.67%, respectively; the elasticity increased by 9.05% and 12.85%, respectively; the cohesiveness increased by 27.78%; and the porosity increased by 7.76% and 21.99%, respectively. Overall, the millet starch-ferulic acid complex can improve the gas-holding capacity of the steamed cake batter and the texture of the steamed cake to a certain extent.

[0094] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for improving the quality of millet rice cake, characterized in that, Includes the following steps: S1. Preparation of millet flour: After coarsely grinding millet, pass it through a 60-90 mesh to obtain sieved millet flour; S2. Extraction and purification of millet starch: At room temperature, sieved millet flour is soaked in sodium hydroxide solution and centrifuged to remove impurities. The precipitation is repeated, and the pH is adjusted with hydrochloric acid until no yellow layer is obtained to obtain the initial millet starch. After washing with ethanol, it is dried to obtain millet starch. S3. Preparation of millet starch-phenolic acid complex: Accurately weigh 3-6g of phenolic acid and millet starch into an RVA aluminum can, add water to a total weight of 25-30g, and process the starch paste in an RVA instrument according to the program. Subsequently, the starch paste is frozen, freeze-dried, ground and filtered to obtain millet starch-phenolic acid complex; the phenolic acid is caffeic acid, gallic acid or ferulic acid; S4. Preparation of steamed cake batter: Weigh out wheat flour, millet flour, millet starch-phenolic acid complex, sugar, yeast, oil, and water in quantitative amounts, and mix them evenly; S5. Fermentation treatment: Place the steamed cake batter in a constant temperature fermentation box for the first fermentation of 0.5-1.5 hours, stir to release gas, and then ferment for a second time of 0.5-2 hours; S6. Steaming the millet cake: Place the fermented millet cake batter in a steamer and steam for 30 minutes to obtain the millet millet cake.

2. The method for improving the quality of millet cake as described in claim 1, characterized in that, The concentration of sodium hydroxide solution in S2 is 0.3% w / v, and the ratio of sieved millet flour to sodium hydroxide solution is 1:3 w / v.

3. The method for improving the quality of millet cake as described in claim 1, characterized in that, In step S2, the sieved millet flour is soaked in sodium hydroxide solution for 12-18 hours.

4. The method for improving the quality of millet cake as described in claim 1, characterized in that, The slurry in S2 is centrifuged at 3500-6500×g for 10-30 min.

5. The method for improving the quality of millet cake as described in claim 1, characterized in that, The concentration of hydrochloric acid in S2 is 0.5-1.5M, and the pH of the starch suspension is adjusted to 7.

0.

6. The method for improving the quality of millet cake as described in claim 1, characterized in that, The amount of phenolic acid added in S3 accounts for 2.5% of the total powder mass.

7. The method for improving the quality of millet cake as described in claim 1, characterized in that, In step S4, the mass ratio of wheat flour to millet flour is 3:

2.

8. The method for improving the quality of millet cake as described in claim 1, characterized in that, The amount of millet starch-phenolic acid complex added is 2.5-5.0% of the mass of the mixed powder.

9. The method for improving the quality of millet cake as described in claim 1, characterized in that, After adding millet starch-phenolic acid complex, the height of the steamed cake is 4.02-5.25cm, the porosity is 37.36-48.31%, the hardness is 10.26-4.91N, the elasticity is 8.95-10.50, the cohesiveness is 0.36-0.49, and the crystallinity is 7.65-6.02%.

Images