Millet dried steamed bun and preparation method thereof

Abstract

The invention relates to the technical field of food processing, and particularly discloses dried millet buns and a preparation method thereof.The dried millet buns are prepared from main materials and auxiliary materials, the main materials comprise millet flour and wheat flour, and the auxiliary materials comprise fresh yeast, water, salt, cane sugar and tea polyphenol; the addition amount of the millet flour is 20% of the total mass of the main materials, and the addition amount of the tea polyphenol is 0.04% of the total mass of the main materials; the preparation method of the millet dried steamed bun comprises the following steps: grinding millet into powder, sieving, and mixing the sieved millet powder with the wheat flour in proportion to obtain a main material; dissolving the table salt, the cane sugar, the tea polyphenol and the fresh yeast in water, adding into the main material, kneading into smooth dough together with the main material, and then rolling and forming; performing fermentation; performing steaming; drying in the air; and slicing and baking to obtain the dried millet bun. A specific amount of millet flour is added into the wheat flour, and a specific amount of tea polyphenol is supplemented, so that the technical problem that the millet dried steamed bun which is high in nutritional value, good in quality and good in storage stability cannot be prepared in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and specifically discloses a millet steamed bun and its preparation method. Background Technology

[0002] Steamed bread slices, also known as bread flakes or mantou slices, are a traditional staple food product. They are made primarily from wheat flour, water, fresh yeast, cane sugar, and salt, through a series of processes including proofing, steaming, natural drying, and baking. They can inhibit and neutralize gastric acid secretion, protect the gastric mucosa, and are convenient to carry and store. With the continuous development of modern food processing technology, the market also has new requirements for the nutritional value of steamed bread slices.

[0003] Millet is a nutritious and versatile grain that plays an important role in our daily diet. It is rich in various beneficial components, and moderate consumption can help strengthen the spleen and stomach, nourish yin and blood, improve eyesight, and clear heat and detoxify.

[0004] With the continuous improvement of living standards and the increasing awareness of health among the public, the nutritional value of millet has been widely recognized. Adding millet flour to wheat flour to make steamed buns would be a very healthy and nutritious food with good market prospects. However, because millet flour does not contain gluten, when mixed with wheat flour to make steamed buns, it weakens the gluten network formed by the wheat flour, resulting in a reduced ability to coat and fix starch granules. Compared with wheat flour, millet flour has a relatively higher content of amylose (about 20%-25%), which retrogrades faster. Therefore, the millet steamed buns made from it harden more quickly during storage, are more prone to hardening, and deteriorate in taste more rapidly. Moreover, compared with wheat flour, millet flour has a higher fat content (about 3%-5%). Although the high fat content of millet flour gives the steamed buns a more fragrant taste, it is more easily oxidized during storage, producing unpleasant flavors such as rancidity, leading to a shorter shelf life. Summary of the Invention

[0005] In view of the problems mentioned in the background art, the present invention provides a millet steamed bun and its preparation method, aiming to solve the technical problem that the existing technology cannot produce millet steamed buns with high nutritional value, good quality and good storage stability.

[0006] On the one hand, the present invention proposes a millet steamed bun, the raw materials for which include main ingredients and auxiliary ingredients. The main ingredients include millet flour and wheat flour, and the auxiliary ingredients include fresh yeast, water, salt, sucrose and tea polyphenols.

[0007] The amount of millet flour added is 20% of the total mass of the main ingredients, and the amount of tea polyphenols added is 0.04% of the total mass of the main ingredients.

[0008] Adding too much millet flour can severely damage the gluten structure and significantly increase the fat content, resulting in a rough texture, increased hardness, and decreased sensory quality in millet steamed buns. Furthermore, the presence of rancid fatty acids can affect the stability of subsequent storage. This invention unexpectedly discovered that when the amount of millet flour added is 20% of the total mass of the main ingredients, the steamed buns exhibit better anti-aging properties, and superior sensory scores and textural characteristics.

[0009] Based on the above-mentioned proportion of millet flour, adding 0.04% of the total mass of tea polyphenols to the main ingredient can effectively reduce the activity of lipoxygenase and fatty acid value in millet steamed buns, inhibit the decomposition of total phenols and flavonoids, slow down the decline in antioxidant activity, thereby slowing down the oxidative rancidity of millet steamed buns, and ultimately improving the storage stability of millet steamed buns, extending the storage time and improving the storage quality.

[0010] This invention uses millet flour and wheat flour as the main ingredients, and adds auxiliary ingredients to make millet steamed buns. This not only enriches the nutritional composition of the steamed buns and improves their nutritional value, but also results in millet steamed buns with high sensory scores, good texture characteristics, good storage stability, and excellent storage quality.

[0011] Furthermore, the amounts of salt and sucrose added are 0.1%-2% and 0.1%-1.5% of the total mass of the main ingredients, respectively.

[0012] The salt ratio described above inhibits unwanted bacteria and controls the activity of fresh yeast, ensuring stable fermentation. It also strengthens the gluten, improves the dough's structure, and enhances its elasticity, resulting in steamed buns with a finer internal structure and a chewier texture, leading to higher quality dried steamed buns. Furthermore, this salt ratio better complements the natural sweetness of the millet and wheat flour, adding layers of flavor to the steamed buns, making them sweet but not cloying. Sucrose plays a multifaceted role, primarily serving the fresh yeast by providing nutrients, promoting fermentation, improving the taste and texture of the millet dried steamed buns, and enhancing their appearance.

[0013] Furthermore, the amounts of salt and sucrose added are 1% and 0.64% of the total mass of the main ingredients, respectively.

[0014] On the other hand, the present invention proposes a method for preparing millet cakes, comprising the following steps:

[0015] S1. Grind the millet into powder, sift it, and mix the sifted millet powder with wheat flour in a certain proportion to obtain the main ingredient;

[0016] S2. Dissolve salt, sucrose, tea polyphenols, and fresh yeast in water, then add the resulting mixture to the main ingredients and knead together to form a smooth dough. Then roll and shape the dough to obtain steamed bun embryos.

[0017] S3. Proof the steamed bun dough, preferably in a proofing chamber;

[0018] S4. After proofing, steam until cooked. It is best to steam it in a steamer with water.

[0019] S5. Allow to air dry;

[0020] S6. Slice and bake.

[0021] Furthermore, in step S1, the millet is Qinzhou yellow millet, which is ground into powder and then passed through a 60-mesh sieve.

[0022] Furthermore, in step S2, salt, sucrose, tea polyphenols, and fresh yeast are first dissolved in water at 48°C, with the water mass being 50% of the total mass of the main ingredients and the fresh yeast mass being 1.2% of the total mass of the main ingredients.

[0023] Furthermore, in step S3, the temperature in the proofing chamber is 50°C, and the proofing time is 30 minutes.

[0024] Furthermore, in step S4, the steaming time is 50 minutes.

[0025] Furthermore, in step S5, the drying time is 24 hours.

[0026] Furthermore, in step S6, baking specifically involves baking at 180°C for 50 minutes.

[0027] The millet steamed bun preparation method proposed in this invention is relatively simple, which is conducive to the large-scale production and promotion of millet steamed buns and has a good market prospect. Attached Figure Description

[0028] Figure 1 The sensory evaluation comparison chart shows the dried bread obtained in Example 1, Blank Control Group 1, and Comparative Examples 8-11.

[0029] Figure 2 This is a comparison chart of the lipoxygenase activity during accelerated storage experiments of the dried steamed buns obtained in Example 1, blank control group 2, and comparative examples 1-7.

[0030] Figure 3 This is a comparison chart of fatty acid values ​​during accelerated storage experiments of the dried steamed buns obtained in Example 1, Blank Control Group 2, and Comparative Examples 1-7.

[0031] Figure 4 This is a comparison chart of the total phenol content of the dried bread obtained in Example 1, blank control group 2, and comparative examples 1-7 during accelerated storage experiments;

[0032] Figure 5 This is a comparison chart showing the flavonoid content of the dried steamed buns obtained in Example 1, Blank Control Group 2, and Comparative Examples 1-7 during accelerated storage experiments.

[0033] Figure 6 This is a comparison chart of the DPPH scavenging rate during accelerated storage experiments of the dried bread obtained in Example 1, blank control group 2, and comparative examples 1-7.

[0034] Figure 7 This is a comparison chart of the ABTS removal rate during accelerated storage experiments of the dried bread obtained in Example 1, blank control group 2, and comparative examples 1-7.

[0035] Figure 8 This is a comparison chart of the FRAP values ​​of the dried steamed buns obtained in Example 1, the blank control group 2, and Comparative Examples 1-7 during accelerated storage experiments;

[0036] in, Figures 2-8 Different lowercase letters above each bar chart indicate significant differences (P<0.05). Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0038] It should be noted that: all technical means not described in detail below are conventional technical means in the art. All raw materials involved in the following embodiments and comparative examples were commercially available. All experimental equipment involved in the following embodiments and comparative examples were commercially available conventional experimental equipment in the art.

[0039] Example 1

[0040] Prepare millet cakes according to the following steps:

[0041] S1. Grind Qinzhou yellow millet into powder using a pulverizer, and obtain millet powder after passing through a 60-mesh sieve. Then mix the millet powder with wheat flour to form 500g of main ingredients, including 100g of millet powder (that is, the amount of millet powder added is 20% of the total mass of the main ingredients, abbreviated as 20% millet powder addition) and 400g of wheat flour.

[0042] S2. Dissolve 5g salt, 3.2g sucrose, 0.2g tea polyphenols (i.e., the amount of tea polyphenols added is 0.04% of the total mass of the main ingredients, abbreviated as 0.04% tea polyphenols added) and 6g fresh yeast in drinking water at 48℃. Then add the resulting mixture to the main ingredients and knead it together with the main ingredients into a smooth dough. After that, roll and shape it to obtain steamed bun embryos.

[0043] S3. Place the steamed bun dough in a proofing room and proof at 50°C for 30 minutes;

[0044] S4. After proofing, steam in a steamer for 50 minutes.

[0045] S5. Remove and air dry for 24 hours;

[0046] S6. Slice and bake at 180°C for 50 minutes.

[0047] Example 2

[0048] Compared with Example 1, in this example, the amount of salt added is 0.5g (that is, the amount of salt added is 0.1% of the total mass of the main ingredients), and the rest is the same as in Example 1.

[0049] Example 3

[0050] Compared with Example 1, in this example, the amount of salt added is 10g (that is, the amount of salt added is 2% of the total mass of the main ingredients), and the rest is the same as in Example 1.

[0051] Example 4

[0052] Compared with Example 1, in this example, the amount of sucrose added is 0.5g (i.e., the amount of sucrose added is 0.1% of the total mass of the main material), and the rest is the same as in Example 1.

[0053] Example 5

[0054] Compared with Example 1, in this example, the amount of sucrose added is 7.5g (i.e., the amount of sucrose added is 1.5% of the total mass of the main material), and the rest is the same as in Example 1.

[0055] Blank control group 1

[0056] Compared with Example 1, no millet powder was added in this control group (i.e., the amount of millet powder added was 0%), and all other aspects were the same as in Example 1.

[0057] Blank control group 2

[0058] Compared with Example 1, no tea polyphenols were added in this control group, but all other aspects remained the same as in Example 1.

[0059] Comparative Example 1

[0060] Compared with Example 1, in this comparative example, the amount of tea polyphenols added is 0.05g (that is, the amount of tea polyphenols added is 0.01% of the total mass of the main material, abbreviated as 0.01% of the amount of tea polyphenols added), and the rest are consistent with Example 1.

[0061] Comparative Example 2

[0062] Compared with Example 1, in this comparative example, the amount of tea polyphenols added is 0.1g (that is, the amount of tea polyphenols added is 0.02% of the total mass of the main material, abbreviated as 0.02% of the amount of tea polyphenols added), and the rest are consistent with Example 1.

[0063] Comparative Example 3

[0064] Compared with Example 1, in this comparative example, the amount of tea polyphenols added is 0.15g (that is, the amount of tea polyphenols added is 0.03% of the total mass of the main material, abbreviated as 0.03% of the amount of tea polyphenols added), and the rest are consistent with Example 1.

[0065] Comparative Example 4

[0066] Compared with Example 1, in this comparative example, the tea polyphenols were adjusted to 0.025g of tert-butylhydroquinone (i.e., the amount of tert-butylhydroquinone added was 0.005% of the total mass of the main material, abbreviated as tert-butylhydroquinone addition amount 0.005%), and the rest remained the same as in Example 1.

[0067] Comparative Example 5

[0068] Compared with Example 1, in this comparative example, the tea polyphenols were adjusted to 0.05g of tert-butylhydroquinone (i.e., the amount of tert-butylhydroquinone added was 0.01% of the total mass of the main material, abbreviated as tert-butylhydroquinone addition amount 0.01%), and all other aspects remained the same as in Example 1.

[0069] Comparative Example 6

[0070] Compared with Example 1, in this comparative example, the tea polyphenols were adjusted to 0.075g of tert-butylhydroquinone (i.e., the amount of tert-butylhydroquinone added was 0.015% of the total mass of the main material, abbreviated as tert-butylhydroquinone addition amount 0.015%), and the rest remained the same as in Example 1.

[0071] Comparative Example 7

[0072] Compared with Example 1, in this comparative example, the amount of tea polyphenols was adjusted to 0.1g of tert-butylhydroquinone (i.e., the amount of tert-butylhydroquinone added was 0.02% of the total mass of the main material, abbreviated as tert-butylhydroquinone addition amount 0.02%), and all other aspects remained the same as in Example 1.

[0073] Comparative Example 8

[0074] Compared with Example 1, in this comparative example, the amount of millet flour added is 50g (that is, the amount of millet flour added is 10% of the total mass of the main ingredients, abbreviated as 10% of the amount of millet flour added), and the rest are consistent with Example 1.

[0075] Comparative Example 9

[0076] Compared with Example 1, in this comparative example, the amount of millet flour added is 150g (that is, the amount of millet flour added is 30% of the total mass of the main ingredients, abbreviated as 30% of the amount of millet flour added), and the rest are consistent with Example 1.

[0077] Comparative Example 10

[0078] Compared with Example 1, in this comparative example, the amount of millet flour added is 200g (that is, the amount of millet flour added is 40% of the total mass of the main ingredients, abbreviated as 40% of the amount of millet flour added), and the rest are consistent with Example 1.

[0079] Comparative Example 11

[0080] Compared with Example 1, in this comparative example, the amount of millet flour added is 250g (that is, the amount of millet flour added is 50% of the total mass of the main ingredients, abbreviated as 50% of the amount of millet flour added), and the rest is consistent with Example 1.

[0081] Performance Test 1: Sensory and Texture

[0082] Sensory quality evaluation, including internal structure, hardness, crispness, and taste, and texture evaluation were conducted on the dried bread obtained from Example 1, blank control group 1, and comparative examples 8-11. The sensory evaluation method referred to "Optimization of Buckwheat Dried Bread Formula" by Hu Junjun et al. (Food Research and Development, 2020, 41(21):75-81). Ten evaluators (5 males and 5 females) were selected for sensory evaluation, and the dried bread was measured using a percentage system. The evaluation criteria are shown in Table 1 below. Texture evaluation referred to "Research and Texture Characteristics Evaluation of Walnut Inulin Biscuits" by Han Xiaojiang et al. (Hubei Agricultural Sciences, 2024, 63(12):151-157, 162). The parameters of the texture analyzer were adjusted as follows: probe P / 36, deformation percentage 40%, initial force 0.5N, force sensor range 1000N. The relevant test results are shown in Table 2.

[0083] Table 1 Sensory Evaluation Criteria for Dried Steamed Buns

[0084]

[0085] Table 2. Effect of millet flour addition on the dry texture properties of steamed buns

[0086]

[0087] like Figure 1As shown, compared with the blank control group 1 (without added millet flour), the internal structure, hardness, crispness, and taste score of the dried bread prepared after adding millet flour were all reduced. Furthermore, the sensory quality decreased with increasing millet flour content, but there was no significant difference in taste as the millet flour content increased from 10% to 50%. An unexpected finding of this invention was that there was no significant difference in the internal structure, hardness, and crispness scores of the dried bread prepared with 10% and 20% millet flour addition. Considering the nutritional value of the product, a millet flour addition of 20% is optimal.

[0088] As shown in Table 2, compared with the blank control group 1 without added millet flour, the hardness, elasticity, adhesiveness, and chewiness of the steamed buns prepared with added millet flour were significantly different (P<0.05). As the amount of added millet flour increased from 10% to 50%, the hardness of the steamed buns increased from 690.50N to 775.83N, the adhesiveness increased from 10.40N to 16.40N, the chewiness increased from 5.24mJ to 6.74mJ, and the elasticity decreased from 0.51mm to 0.32mm. Hardness, adhesiveness, and chewiness were negatively correlated with sensory quality. There was no significant difference in the textural properties of the steamed buns prepared with 10% and 20% added millet flour. These conclusions are consistent with the conclusions of the sensory evaluation.

[0089] Performance Test 2: Storage Quality

[0090] Accelerated storage experiments were conducted on the dried bread obtained from Example 1, blank control group 2, and comparative examples 1-7. During the experiment, the corresponding dried bread was placed in a self-sealing bag and stored in a constant temperature and humidity chamber at 50°C and 50% humidity for 28 days. Samples were taken every 7 days to determine their physicochemical indicators. Each indicator was tested in three independent replicates. The mean and standard deviation were calculated using Excel 2021, and the difference was analyzed using SPSS 25.0 (P<0.05). Plotting was performed using Origin 2024.

[0091] It should be noted that:

[0092] (1) For ease of representation in the figure, the blank control group 2 without added tea polyphenols is labeled CK; Comparative Examples 1, 2, 3, and 1 with added tea polyphenols of 0.01%, 0.02%, 0.03%, and 0.04% are labeled C1, C2, C3, and C4 respectively; and Comparative Examples 4, 5, 6, and 7 with added tert-butylhydroquinone of 0.005%, 0.01%, 0.015%, and 0.02% are labeled T1, T2, T3, and T4 respectively. For ease of description, tert-butylhydroquinone is abbreviated as TBHQ.

[0093] (2) The physicochemical indicators mentioned include lipoxygenase activity, fatty acid value, total phenol content, flavonoid content, DPPH scavenging rate, ABST scavenging rate, and FRAP value.

[0094] The method for determining lipoxygenase activity was slightly modified from the method described by Liu Xiaojiao et al. in [Effects of Different Treatments on Lipoxygenase Activity and Quality in Highland Barley [J]. Food Research and Development, 2021, 42(07):39-44]. The specific method for determining lipoxygenase activity was as follows: 2.5g of millet cake powder was added to 20mL of phosphate buffer solution with a pH of 7.0 and a concentration of 0.05mol / L. After incubating on ice for 10min, the mixture was centrifuged at 4℃ and 8000r / min for 15min. The supernatant was the crude enzyme extract. Borax-boronic acid buffer solution was used as a blank. 200μL of 0.004mmol / L linoleic acid substrate was mixed with borax-boronic acid buffer solution and 50μL of crude enzyme extract solution for determination. The change in OD value within 2min was recorded. The formula for calculating lipoxygenase activity is as follows:

[0095]

[0096] In the formula: Δt is the reaction time, in min; V0 is the total volume of crude enzyme extract, in mL; V1 is the amount of crude enzyme extract added, in mL; V2 is the total volume of the reaction system, in mL; m is the sample mass, in g; ΔOD 234nm The change in optical density at 234 nm over time Δt.

[0097] The determination of fatty acid value refers to the test method in GB / T15684-2015 "Determination of Fatty Acid Value of Milled Grain Products".

[0098] The method for determining the total phenol content was slightly modified from the method in Li Nan et al.'s [Analysis of polyphenols, flavonoids and antioxidant activity of black beans at different germination stages [J]. Food Industry, 2023, 44(08):139-143]. The specific method for determining the total phenol content was as follows: (1) A standard curve was prepared by setting a concentration gradient using gallic acid as the standard: y = 0.0828x + 0.0215, R 2 =0.9948; (2) Weigh 1g of millet steamed bun powder into a 10mL centrifuge tube, add 5mL of methanol aqueous solution with a volume fraction of 70%, centrifuge after a 70℃ water bath; take 0.8mL of supernatant into a 10mL volumetric flask, add 1mL of Folin-Ciocalteu solution and 1mL of Na2CO3 solution with a mass fraction of 7.5%, make up to volume with distilled water, let stand at room temperature for 30min, and then measure its absorbance at a wavelength of 765nm; (3) Calculate the total phenol content in millet steamed bun by referring to the standard curve.

[0099] The specific method for determining the flavonoid content was slightly modified from the method in [Comparison of Main Nutrients and Elements in Three Jujube Fruits [J]. Food and Fermentation Industries, 2014, 40(05): 161-165] by Nan Haijuan et al. The specific method for determining the flavonoid content is as follows: (1) Set up a standard curve y = 2.1769x + 0.0141 using rutin as the standard and set up a concentration gradient. 2 =0.9921; (2) Weigh 2g of millet cake powder into a 10mL centrifuge tube, add 5mL of 70% methanol aqueous solution, centrifuge after 70℃ water bath to obtain supernatant; take 2mL of supernatant into a 25mL volumetric flask, add 2mL of 0.1mol / L AlCl3 solution and 3mL of 1mol / L CH3COOK solution, make up to volume with 70% methanol aqueous solution, let stand at room temperature for 30min, and measure absorbance at 420nm wavelength; (3) Calculate the flavonoid content in millet cake by referring to the standard curve.

[0100] The methods for determining DPPH scavenging rate and ABST scavenging rate were based on the study of the physicochemical properties of alfalfa powder and its preparation process for chewable tablets by Lai Sitong et al. (Shanxi Agricultural University, 2020).

[0101] The method for determining FRAP values ​​was improved based on the work of Li Huabin et al., "Evaluation of Two Methods for Extracting Antioxidants from Traditional Chinese Medicine" (Chinese Culture Forum, 2008, (S1): 251-253): First, a standard curve was prepared by setting a concentration gradient with different concentrations of FeSO4: y = 1.2118x + 0.004, R... 2 =0.9988, then take 200 μL of the crude enzyme extract into a centrifuge tube, add 4 mL of TPTZ working solution (for the method of obtaining it, see Benzie IFF, Strain JJ (1996) Anal Biochem 239:70-76), then react at 37℃ for 10 min and measure the absorbance at 593 nm. Finally, calculate the FRAP value according to the standard curve equation.

[0102] like Figures 2-8 As shown in the following:

[0103] (1) During storage, lipoxygenase produces unpleasant odors, reduces nutritional quality, and shortens the storage period to some extent. Under accelerated storage conditions, the changes in lipoxygenase activity with the addition of different concentrations of antioxidants are shown in the following trends. Figure 2As shown, with the extension of the storage time of millet steamed buns, the lipoxygenase activity of groups T1, T2, T3, T4, C1, C2, C3, and C4 was lower than that of the CK group, indicating that the addition of tea polyphenols or TBHQ to millet steamed buns can inhibit lipoxygenase activity. The lipoxygenase activity (U / g) of group C4 was the lowest, at 0.81, 0.73, 0.50, 0.33, and 0.19, respectively. Moreover, there were significant differences between the CK group and groups T1, T2, T3, T4, C1, C2, C3, and C4 (P < 0.05). Therefore, group C4 (with 0.04% tea polyphenols added) can better maintain the quality of millet steamed buns.

[0104] (2) During storage, antioxidants can delay fat oxidation, reduce the formation of intermediate products such as peroxides, and thus inhibit fat hydrolysis, slowing down the production rate of free fatty acids. Under accelerated storage conditions, the changes in fatty acid values ​​after adding different concentrations of antioxidants are shown in the following figures. Figure 3 As shown, with the extension of the storage time of millet steamed buns, the fatty acid values ​​of groups T1, T2, T3, T4, C1, C2, C3, and C4 were all lower than those of the CK group, indicating that the addition of tea polyphenols or TBHQ to millet steamed buns can inhibit fat hydrolysis and reduce fatty acid formation. The fatty acid value (mg / 100g) of group C4 was the lowest, at 25.59, 40.76, 70.69, 85.85, and 94.59, respectively, and there was a significant difference between group C4 and group CK (P<0.05). Therefore, group C4 (tea polyphenol addition of 0.04%) can better maintain the quality of millet steamed buns.

[0105] (3) Millet flour contains abundant antioxidants that have a positive impact on human health, such as phenolic acids and flavonoids. During storage, polyphenols undergo oxidation and degradation, therefore the total phenol content decreases with prolonged storage time. Under accelerated storage conditions, the effects of different concentrations of antioxidants on the total phenol content of millet flour cakes are as follows: Figure 4 As shown, with the extension of the storage time of millet cakes, the total phenolic content of groups T1, T2, T3, T4, C1, C2, C3, and C4 was higher than that of the CK group. This is because tea polyphenols and TBHQ are phenolic substances themselves, and their addition may increase the total phenolic content in the samples. The total phenolic content (mg / kg) of group C4 was the highest, at 7.62, 7.33, 6.63, 6.17, and 5.52, respectively, and there was a significant difference between group C4 and group CK (P < 0.05). Therefore, group C4 (tea polyphenol addition of 0.04%) was the most effective in increasing the total phenolic content.

[0106] During storage, the flavonoids in dried millet buns undergo oxidation, resulting in a slow overall decrease in flavonoid content over extended storage time. Accelerated storage accelerates flavonoid oxidation, leading to a faster decline in flavonoid content. The effects of different concentrations of antioxidants on the flavonoid content of millet dried millet buns under accelerated storage conditions are as follows: Figure 5 As shown, with the extension of the storage time of millet cakes, the flavonoid content of groups T1, T2, T3, T4, C1, C2, C3, and C4 was higher than that of the CK group. Among them, the flavonoid content of group C4 was the highest, and there was a significant difference between group C4 and group CK (P < 0.05). It can be seen that the addition of 0.04% tea polyphenols is more helpful in protecting flavonoids from oxidative damage, thus effectively slowing down the decline in their content.

[0107] (4) A higher DPPH scavenging rate indicates stronger antioxidant capacity. The effects of different concentrations of antioxidants on the DPPH scavenging rate of millet cakes during accelerated storage are as follows: Figure 6 As shown, the main ingredients used to make millet cakes naturally contain certain antioxidants such as phenolic acids, flavonoids, vitamins, and minerals, and the control group (CK) also possesses a certain antioxidant capacity. With prolonged storage, the DPPH scavenging rates of groups T1, T2, T3, T4, C1, C2, C3, and C4 were all higher than that of the control group, indicating that adding tea polyphenols or TBHQ can increase the DPPH scavenging rate. Among them, group C4 had the highest DPPH scavenging rate, at 62.86%, 52.30%, 48.51%, 43.89%, and 37.57%, respectively, and there was a significant difference between group C4 and group CK (P<0.05). Therefore, within the same storage period, adding 0.04% tea polyphenols provides stronger antioxidant capacity and can more effectively scavenge DPPH free radicals.

[0108] (5) A higher ABTS scavenging rate indicates stronger antioxidant capacity. The effects of different concentrations of antioxidants on the ABTS scavenging rate of millet cakes during accelerated storage are as follows: Figure 7 As shown, the main ingredients used to make millet cakes naturally contain phenolic acids, flavonoids, and vitamins with antioxidant activity, and the control group (CK) also possesses a certain antioxidant capacity. With prolonged storage of the millet cakes, the ABTS scavenging rates of groups T1, T2, T3, T4, C1, C2, C3, and C4 were all higher than that of the control group (CK), indicating that adding tea polyphenols or TB HQ can increase the ABTS scavenging rate. The highest ABTS scavenging rate was observed in group C4, at 51.47%, 47.00%, 35.64%, 28.02%, and 21.80%, respectively, with a significant difference between the control group and group C4 (P<0.05). Therefore, within the same storage period, adding 0.04% tea polyphenols provides stronger antioxidant capacity and can more effectively scavenge ABTS.

[0109] (6) The higher the FRAP value, the stronger the total antioxidant capacity. The effects of different concentrations of antioxidants on the FRAP value of millet cakes during accelerated storage are as follows: Figure 8 As shown, with the extension of the storage time of millet cakes, the FRAP values ​​of groups T1, T2, T3, T4, C1, C2, C3, and C4 were all higher than those of the CK group, indicating that the addition of tea polyphenols or TBHQ can increase the FRAP value. Among them, the FRAP value of group C4 was the highest, at 0.264, 0.244, 0.216, 0.212, and 0.207 respectively, and there was a significant difference between group C4 and group CK (P<0.05). It can be seen that within the same storage period, the addition of 0.04% tea polyphenols can more effectively improve the FRAP value and has a stronger antioxidant capacity.

[0110] In summary, the millet dried bread prepared using the scientifically obtained formula of this invention has high nutritional value, good sensory qualities, excellent texture, strong anti-aging ability, is not easy to harden, and has good storage stability and storage quality with a long shelf life. Moreover, the preparation method of this formula is simple and has good market prospects, solving the technical problem that existing technologies cannot produce millet dried bread with high nutritional value, good quality and good storage stability.

[0111] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions, and variations to the above embodiments within the scope of the present invention. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

Claims

1. A type of millet steamed bun, characterized in that, Its preparation materials include main ingredients and auxiliary ingredients. The main ingredients include millet flour and wheat flour, and the auxiliary ingredients include fresh yeast, water, salt, sucrose and tea polyphenols. The amount of millet powder added is 20% of the total mass of the main ingredients, and the amount of tea polyphenols added is 0.04% of the total mass of the main ingredients.

2. The millet steamed bun according to claim 1, characterized in that, The amounts of salt and sucrose added are 0.1%-2% and 0.1%-1.5% of the total mass of the main ingredients, respectively.

3. The millet steamed bun according to claim 1, characterized in that, The amounts of salt and sucrose added are 1% and 0.64% of the total mass of the main ingredients, respectively.

4. A method for preparing millet cake as described in any one of claims 1-3, characterized in that, The following steps are included: S1. Grind the millet into powder, sift it, and mix the sifted millet powder with wheat flour in a certain proportion to obtain the main ingredient; S2. Dissolve salt, sucrose, tea polyphenols, and fresh yeast in water, then add the resulting mixture to the main ingredients and knead together to form a smooth dough. Then roll and shape the dough to obtain steamed bun embryos. S3. Let the dough rise; S4. Steam until cooked after proofing; S5. Allow to air dry; S6. Slice and bake.

5. The method for preparing millet cake according to claim 4, characterized in that, In step S1, the millet is Qinzhou yellow millet, which is ground into powder and then passed through a 60-mesh sieve.

6. The method for preparing millet cake according to claim 4, characterized in that, In step S2, salt, sucrose, tea polyphenols, and fresh yeast are first dissolved in water at 48°C. The mass of water is 50% of the total mass of the main ingredients, and the mass of fresh yeast is 1.2% of the total mass of the main ingredients.

7. The method for preparing millet cake according to claim 4, characterized in that, In step S3, the proofing temperature is 50℃ and the proofing time is 30 minutes.

8. The method for preparing millet cake according to claim 4, characterized in that, In step S4, the steaming time is 50 minutes.

9. The method for preparing millet cake according to claim 4, characterized in that, In step S5, the drying time is 24 hours.

10. The method for preparing millet cake according to claim 4, characterized in that, In step S6, the baking process specifically involves baking at 180°C for 50 minutes.

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