Enzymatically hydrolyzed millet flour and preparation method thereof

Abstract

The present invention provides an enzymolysis millet powder and a preparation method thereof, wherein the enzymolysis millet cereal powder is prepared by pre-treatment, grinding, primary enzymolysis, secondary enzymolysis, filtration separation, blending, homogenization and spray drying of raw millet. The enzymolysis millet powder and the preparation method thereof provided by the present invention improve the added value of millet products; compared with commercially available raw millet powder, the millet powder of the present invention is not newly ground millet powder, but a kind of instant food, which can be prepared and drunk immediately, while the commercially available newly ground cooked millet powder lacks sweetness when prepared, and the millet powder product prepared by enzymolysis is convenient to use, has good flavor, has a certain sweetness without adding white sugar, and provides a new choice for consumers in millet products.

Description

Technical Field

[0001] The invention relates to enzymolysis millet flour and a preparation method thereof. Background Art

[0002] At present, millet is mainly consumed in traditional foods such as millet porridge and millet cakes on the market. The consumption method is single and the product varieties are few. The development of enzymatic millet powder has changed the traditional consumption method of millet. The millet powder on the market is basically freshly ground millet powder, which is mostly used to make snacks, cakes, steamed buns and other products, but cannot be made into instant drinks. The newly ground millet powder on the market lacks sweetness when mixed. The development of enzymatic millet powder has changed the traditional consumption method of millet, which is convenient and fast. Market research shows that the scale and potential of the millet market are large, but the conditions for forming scale demand are not yet in place. Therefore, improving the comprehensive utilization rate of millet crops, deeply exploring millet derivative products, and forming industrialized economies of scale will have a high promoting effect on millet crops and agricultural economy. Compared with freshly ground millet powder, enzymatic millet powder has a better market prospect because of its convenience and good flavor.

[0003] In the prior art, there are few reports on the technology of enzymatic hydrolysis of millet powder. The patent with publication number CN116649533A discloses a method for producing enzymatic hydrolysis of millet powder, but the method does not specifically provide a production process of enzymatic hydrolysis of millet powder, but only provides a research method for producing enzymatic hydrolysis of millet powder. The present invention provides an enzymatic hydrolysis of millet powder and a specific method for its preparation through specific experiments. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art, provide an enzymolysis millet powder and a preparation method thereof, improve the added value of millet products, and extend the industrial chain thereof. Compared with commercially available raw millet powder, the millet powder of the present invention is not newly ground millet powder, but a kind of instant food, which can be prepared and drunk immediately, while the commercially available newly ground cooked millet powder lacks sweetness when prepared. The millet powder product prepared by enzymolysis is convenient to use, has good flavor, has a certain sweetness without adding white sugar, and provides a new choice for consumers in terms of millet products.

[0005] To achieve the above object, the technical solution of the present invention is a method for preparing enzymatically hydrolyzed millet flour, comprising the following steps:

[0006] S1: Pretreatment: steaming the raw millet;

[0007] S2: preparing millet slurry: cooling the steamed millet and then grinding it to obtain millet slurry;

[0008] S3: Enzymatic hydrolysis: The millet slurry in step S2 is heated to 60-65°C, and medium-temperature amylase and saccharifying enzyme are added for primary enzymatic hydrolysis. After the primary enzymatic hydrolysis, the temperature is raised to 80-95°C, and high-temperature amylase is added for secondary enzymatic hydrolysis to obtain millet liquid;

[0009] S4: Cooling: After the secondary enzymatic hydrolysis, the millet liquid is cooled to room temperature;

[0010] S5: Filtration and separation: filtering and separating the millet liquid at room temperature to obtain enzymatically hydrolyzed millet liquid;

[0011] S6: Preparation: Add water and auxiliary materials to the enzymatic millet solution, the preparation temperature is 55-65°C, and the stirring time is 15-20min;

[0012] S7: homogenizing: homogenizing the enzymatically hydrolyzed millet solution prepared in step S6, with a homogenizing temperature of 60° C. and a homogenizing pressure of 25-30 MPa;

[0013] S8: spray drying: spray drying the homogenized enzymolysis millet liquid in step S8, the spray drying inlet air temperature is 125°C, the drying outlet air temperature is 95°C; the return air temperature is 105°C, and the outlet air temperature is 95°C. The present invention designs an enzymolysis millet cereal beverage, which is prepared by steaming, grinding, primary enzymolysis, secondary enzymolysis, filtering and separation, blending, homogenization and spray drying the raw millet. During the steaming process, the raw bitterness of the millet is removed, and the enzymolysis time and the amount of enzyme added are controlled to ensure that the De value (i.e., glucose value: Dextrose Equivalent) of the enzymolysis millet liquid is within a suitable range, and the De value is too high, which will cause severe saccharification and stickiness, and the De value is too low, which will cause excessive viscosity to block the spray drying nozzle. The enzymolysis millet powder of this method has the fragrance of millet itself, and at the same time, it has the characteristics of silky taste and no irritation when brewed.

[0014] A further technical solution is that in step S1, the raw millet is placed in a pressure steamer and steamed until the millet absorbs water and becomes soft and has no raw bitter taste;

[0015] In the step S2, after the millet is steamed, the millet is rinsed with cold water to cool down to below 60° C. and then put into a colloid mill for grinding to obtain millet slurry;

[0016] In the step S4, the millet liquid after the secondary enzymatic hydrolysis is cooled to room temperature through heat exchange;

[0017] In the step S5, the room temperature millet liquid is centrifuged through a 100-mesh sieve to obtain an enzymatically hydrolyzed millet liquid;

[0018] In the step S6, the enzymatic millet liquid is added with a corresponding amount of water and auxiliary materials according to the designed formula, the mixing temperature is 55-65° C., and the stirring time is 15-20 minutes. The millet is steamed in a pressure steamer for 40-50 minutes until the millet has no raw bitterness.

[0019] A further technical solution is that in step S1, rinse with cold water three times, drain the water, close the lid and steam for 40-50 minutes. Rinse the millet with cold water before grinding to reduce the temperature of the millet to below 60°C, and grind it with a colloid mill; the specific requirements are: use a suitable colloid milling equipment to grind the millet to a coarseness of about 12 mesh (that is, the main requirement for the colloid mill is the grinding fineness requirement), the equipment is a colloid mill, and different equipment can be replaced according to the output.

[0020] A further technical solution is that in step S2, a colloid mill is used to grind the millet to 12±3 mesh.

[0021] A further technical solution is that in step S3, the enzymatic hydrolysis time of the first enzymatic hydrolysis is 50 minutes, the addition amount of medium-temperature amylase is 0.05-0.20%, the addition amount of saccharifying enzyme is 0.05-0.20%, the enzymatic hydrolysis temperature is 60-65°C, and the enzymatic hydrolysis pH is 6-7; the enzymatic hydrolysis time of the second enzymatic hydrolysis is 20 minutes, the addition amount of high-temperature amylase is 0.05%-0.1%, the enzymatic hydrolysis temperature is 80-95°C, and the enzymatic hydrolysis pH is 6-7. Medium-temperature amylase and saccharifying enzyme are used in the first enzymatic hydrolysis. The enzymatic hydrolysis time is 50 minutes, the addition amount of medium-temperature amylase is 0.05-0.20%, the addition amount of saccharifying enzyme is 0.05-0.20%, the enzymatic hydrolysis temperature is 60-65°C, and the enzymatic hydrolysis pH is 6-7. After the first enzymolysis, the feed liquid is heated to 80-95°C for secondary enzymolysis, and high temperature amylase is used in the secondary enzymolysis, the enzymolysis time is 20 minutes, the addition amount of high temperature amylase is 0.05%-0.1%, the enzymolysis temperature is 80-95°C, and the enzymolysis pH is 6-7. Between the secondary enzymolysis and the filtration separation process, a heat exchange process for cooling the feed liquid to room temperature is provided; and the room temperature feed liquid is centrifuged through a 100-mesh screen to obtain an enzymolysis millet liquid.

[0022] A further technical solution is that in step S6, the mass fractions of each material added are as follows: 90-99 parts of enzymatic millet liquid, 1-2 parts of vegetable oil, and 0.5-1.5 parts of salt. The enzymatic millet liquid is added with corresponding water and auxiliary materials according to the formula, the mixing temperature is 55-65°C, and the stirring time is 15-20min. The prepared enzymatic millet liquid is homogenized at a homogenization temperature of 60°C and a homogenization pressure of 25-30MPa.

[0023] The inlet air temperature of the homogenized enzymatic millet liquid during spray drying is 125°C, and the outlet air temperature is 95°C. The return air temperature is 105°C, and the outlet air temperature is 95°C; the particle size of the obtained enzymatic millet powder is 300±30nm. The feed flow rate during spray drying varies according to the size of the tower body. The feed flow rate is a variable that controls the outlet air temperature in the tower, and the outlet air temperature is mainly controlled.

[0024] The invention also provides enzymolysis millet powder, which is prepared by adopting the preparation method of the enzymolysis millet powder.

[0025] The advantages and beneficial effects of the invention are that the raw bitterness of millet is removed during the steaming process, while the enzymolysis time and the amount of enzyme added are controlled to ensure that the De value of the enzymolysis millet liquid is within a suitable range, so as to prevent the De value from being too high, resulting in serious saccharification and the sticking tower phenomenon, and the De value from being too low, resulting in excessive viscosity and blocking the spray drying nozzle. The enzymolysis millet powder prepared by the method has the fragrance of millet itself, and has the characteristics of being smooth in taste and not irritating the throat when brewed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a schematic diagram of a finished product of enzymatically hydrolyzed millet flour. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0028] Embodiment 1:

[0029] S1: Place the raw millet in a pressure steamer, rinse it with cold water three times, drain the water, close the lid and steam for 40 minutes. There is no bitter smell of millet, and the millet absorbs water and expands to become soft. The steam pressure in the steamer is 0.4Mpa and the temperature is 147℃.

[0030] S2: The millet steamed in S1 is rinsed with cold water to cool down to 55° C., and then put into a colloid mill for grinding to obtain millet slurry;

[0031] During the grinding process, cold water is added to mix, the material-water ratio is 1:3, and the grinding coarseness is 1mm;

[0032] S3: The millet slurry in step S2 is heated to 62° C. in a constant temperature water bath, and medium temperature amylase and saccharifying enzyme (medium temperature amylase and saccharifying enzyme can be purchased directly from the market) are added for primary enzymolysis with continuous stirring. After the primary enzymolysis is completed, the temperature is further heated to 85° C. in a constant temperature water bath, and high temperature amylase (high temperature enzyme is high temperature enzyme model AUS62018 of Novozymes) is added for secondary enzymolysis with continuous stirring;

[0033] The first enzymatic hydrolysis used medium-temperature amylase and saccharifying enzyme. The enzymatic hydrolysis time was 50 minutes, the addition amount of medium-temperature amylase was 0.1%, the addition amount of saccharifying enzyme was 0.05%, the enzymatic hydrolysis temperature was 62°C, and the enzymatic hydrolysis pH was 6-7. The second enzymatic hydrolysis used high-temperature amylase, the enzymatic hydrolysis time was 20 minutes, the addition amount of high-temperature amylase was 0.05%, the enzymatic hydrolysis temperature was 85°C, and the enzymatic hydrolysis pH was 6-7.

[0034] S4: Cool the millet liquid obtained in step S3 to 30° C. in a constant temperature water bath.

[0035] S5: The 30° C. millet liquid obtained in step S4 is centrifuged through a 100-mesh sieve to obtain an enzymolysis millet liquid, and the solid content of the enzymolysis millet liquid is determined to be 26%;

[0036] S6: 98 parts of enzymatic millet liquid, 1.8 parts of vegetable oil, and 0.13 parts of salt were placed in a 10 L stainless steel barrel, stirred for 15 min, and maintained at 60° C. in a constant temperature water bath.

[0037] S7: homogenizing the enzymatically hydrolyzed millet solution prepared in step S6, with the homogenization temperature being 60° C. and the homogenization pressure being 25 MPa;

[0038] S8. The total solid content of the enzymolysis millet liquid after homogenization is 28%. The spray drying is carried out using a circulating enrichment spray drying tower (or a closed circulation drying tower in the prior art), with a feed rate of 5 kg / h, a spray drying inlet air temperature of 125°C, and a drying outlet air temperature of 95°C. The return air temperature is 105°C, and the outlet air temperature is 95°C.

[0039] S9. The product is sieved to remove larger lumps. The product particle size is 300nm. Figure 1 Finished product shown.

[0040] Comparative Example 1:

[0041] S1: Place the raw millet in a pressure steamer, rinse it with cold water three times, drain the water, close the lid and steam for 40 minutes, until there is no bitter smell of millet, and the millet absorbs water and swells to become soft;

[0042] S2: The millet steamed in S1 is rinsed with cold water to cool down to 55° C., and then put into a colloid mill for grinding to obtain millet slurry;

[0043] During the grinding process, cold water is added to mix, the material-water ratio is 1:3, and the grinding coarseness is 1mm;

[0044] S3: The millet slurry in step S2 is heated to 62° C. in a constant temperature water bath, and medium temperature amylase and saccharifying enzyme are added for primary enzymolysis with continuous stirring. After the primary enzymolysis is completed, the millet slurry is heated to 85° C. in a constant temperature water bath, and high temperature amylase is added for secondary enzymolysis with continuous stirring;

[0045] The first enzymatic hydrolysis used medium-temperature amylase and saccharifying enzyme. The enzymatic hydrolysis time was 60 minutes, the addition amount of medium-temperature amylase was 0.15%, the addition amount of saccharifying enzyme was 0.05%, the enzymatic hydrolysis temperature was 62°C, and the enzymatic hydrolysis pH was 6-7. The second enzymatic hydrolysis used high-temperature amylase, the enzymatic hydrolysis time was 20 minutes, the addition amount of high-temperature amylase was 0.05%, the enzymatic hydrolysis temperature was 85°C, and the enzymatic hydrolysis pH was 6-7.

[0046] S4: Cool the millet liquid obtained in step S3 to 30° C. in a constant temperature water bath.

[0047] S5: The 30° C. millet liquid obtained in step S4 is centrifuged through a 100-mesh sieve to obtain an enzymolysis millet liquid, and the solid content of the enzymolysis millet liquid is determined to be 26%;

[0048] S6: 98 parts of enzymatic millet liquid, 1.8 parts of vegetable oil, and 0.13 parts of salt were placed in a 10 L stainless steel barrel, stirred for 15 min, and maintained at 60° C. in a constant temperature water bath.

[0049] S7: homogenizing the enzymatically hydrolyzed millet solution prepared in step S6, with the homogenization temperature being 60° C. and the homogenization pressure being 25 MPa;

[0050] S8. The total solid content of the enzymolysis millet liquid after homogenization is 28%. The spray drying is carried out using a circulating enrichment spray drying tower (or a closed circulation drying tower in the prior art), with a feed rate of 5 kg / h, a spray drying inlet air temperature of 125°C, and a drying outlet air temperature of 95°C. The return air temperature is 105°C, and the outlet air temperature is 95°C.

[0051] S9. The product is sieved to remove larger lumps. The particle size of the product is 300nm.

[0052] The difference between the embodiment and comparative example 1 is that the enzyme dosage and enzymolysis time of the two experiments are different. The enzymolysis time of the embodiment is 50min, the addition amount of medium-temperature amylase is 0.1%, and the addition amount of saccharifying enzyme is 0.05%. The enzymolysis time of comparative example 1 is 1h, the addition amount of medium-temperature amylase is 0.15%, and the addition amount of saccharifying enzyme is 0.05%; the De value of the enzymolysis millet liquid of the embodiment is measured to be 28.6, and the De value of the enzymolysis millet liquid of comparative example 1 is 42. According to the production experience and process and equipment requirements of the company, the De value of the enzymolysis liquid for powder spraying is generally required to be between 25-38, to prevent the De value from being too high and causing the serious saccharification and the sticking tower phenomenon and the De value from being too low and causing the viscosity to be too high and blocking the spray drying nozzle. The De value of comparative example 1 is too high, resulting in the sticking tower phenomenon when spraying, and the enzymolysis conditions of the embodiment are suitable, and the powder spraying is smooth.

[0053] Determination of agglomeration rate

[0054] The caking rate is a physical quantity used to characterize the difference in powder dispersion during mixing. Generally, the smaller the caking rate, the better the dispersion of the dry powder during mixing. The method for determining the caking rate is as follows: 100 mL of boiling water is added to a beaker, 10 g of dried millet powder is added, and the mixture is stirred on an automatic stirrer at a speed of 120 r / min. After stirring for 20 seconds at a uniform speed, the mixture is passed through an 80-mesh sieve, and the lumps that do not pass through the sieve are dried to a constant weight, and the mass is weighed as M (g).

[0055] X(%)=M*100 / [10*(1-W)]

[0056] Where: W-moisture content of millet flour, unit %.

[0057] Determination of water absorption and water solubility

[0058] Accurately weigh 2.5g millet powder sample and put it into a weighed centrifuge tube with a lid. Add 30mL of distilled water, cover the lid and shake. After the sample is fully dispersed in the water, place the centrifuge tube in a 30℃ water bath for 30min, and shake it intermittently 5 times during the process. After taking it out, centrifuge it at 4000r / min for 20min, inject the supernatant into a covered aluminum box of known weight, dry the precipitate and supernatant at 105℃, cool it, and weigh it. The water absorption (WAI) and water solubility (WSI) calculation formula are as follows:

[0059] WSI = supernatant dry weight / sample dry weight

[0060] WAI = weight of water in the sediment / dry weight of the sediment

[0061] The results are shown in Table 1

[0062] Table 1

[0063]

[0064] It can be seen that the preparation method of the enzymatically hydrolyzed millet flour provided by the present invention is feasible, and the millet flour product prepared by enzymatic hydrolysis is easy to use, has good flavor, has a natural sweetness after enzymatic hydrolysis, and compared with newly ground millet flour, has good water solubility, water absorption and dispersion properties.

[0065] 1. In the existing medium-temperature enzyme hydrolysis system, the millet slurry will gelatinize during the process of heating and inactivating the enzyme, and the slurry will become viscous, resulting in blockage of pipes and plate heat exchangers. This technology adds high-temperature enzyme hydrolysis and combines it with medium-temperature enzymes to make the millet liquid hydrolyzed more fully and prevent blockage.

[0066] 2. After the millet enzymatic hydrolyzed slurry is prepared, the liquid has a very strong powdery texture and is very irritating to the throat. It is not smooth after being sprayed into powder. This technology improves the texture by adding a certain amount of fat. The slurry becomes much smoother, and the sprayed powder also becomes silky and smooth.

[0067] 3. The raw materials of this technology are completely derived from millet, without any other raw materials. The enzymatic hydrolysate produced will have the above-mentioned situation 2. This technology improves the unpleasant taste of powdery texture through formulation, rather than improving it by adding different raw materials and mixing them.

[0068] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing enzymatically hydrolyzed millet flour, characterized in that: The following steps are involved: S1: Pretreatment: steaming the raw millet; S2: preparing millet slurry: cooling the steamed millet and then grinding it to obtain millet slurry; S3: Enzymatic hydrolysis: The millet slurry in step S2 is heated to 60-65°C, and medium-temperature amylase and saccharifying enzyme are added for primary enzymatic hydrolysis. After the primary enzymatic hydrolysis, the temperature is raised to 80-95°C, and high-temperature amylase is added for secondary enzymatic hydrolysis to obtain millet liquid; S4: Cooling: After the secondary enzymatic hydrolysis, the millet liquid is cooled to room temperature; S5: Filtration and separation: filtering and separating the millet liquid at room temperature to obtain enzymatically hydrolyzed millet liquid; S6: Preparation: Add vegetable oil and salt to the enzymatic millet liquid, the mass parts of each material are as follows: 90-99 parts of enzymatic millet liquid, 1-2 parts of vegetable oil, 0.5-1.5 parts of salt, the preparation temperature is 55-65°C, and the stirring time is 15-20min; S7: homogenizing: homogenizing the enzymatically hydrolyzed millet solution prepared in step S6, with a homogenizing temperature of 60° C. and a homogenizing pressure of 25-30 MPa; S8: spray drying: spray drying the homogenized enzymatic millet liquid in step S8, with the spray drying air inlet temperature of 125°C and the drying air outlet temperature of 95°C; the return air temperature of 105°C and the air outlet temperature of 95°C; S9: The product is sieved to remove larger lumps; the product particle size is 300nm; In the step S3, the enzymatic hydrolysis time of the primary enzymatic hydrolysis is 50 minutes, the addition amount of the medium-temperature amylase is 0.05-0.20% of the mass of the millet slurry, the addition amount of the saccharifying enzyme is 0.05-0.20%, the enzymatic hydrolysis temperature is 60-65°C, and the enzymatic hydrolysis pH is 6-7; the enzymatic hydrolysis time of the secondary enzymatic hydrolysis is 20 minutes, the addition amount of the high-temperature amylase is 0.05%-0.1%, the enzymatic hydrolysis temperature is 80-95°C, and the enzymatic hydrolysis pH is 6-7; In the step S2, cold water is added during the grinding process, the material-water ratio is 1:3, and the grinding coarseness is 1 mm; In the step S3, a first enzymatic hydrolysis is performed with continuous stirring; a second enzymatic hydrolysis is performed with continuous stirring; In the step S4, the millet liquid obtained in the step S3 is cooled to 30° C. in a constant temperature water bath; the solid content of the enzymatically hydrolyzed millet liquid is determined to be 26%; During spray drying, the feed flow rate varies according to the size of the tower. The feed flow rate is a variable that controls the outlet air temperature in the tower, and the outlet air temperature is mainly controlled.

2. The method for preparing enzymolysis millet flour according to claim 1, characterized in that: In the step S1, the raw millet is placed in a pressure steamer and steamed until the millet absorbs water and becomes soft and has no raw bitter taste; In the step S2, after the millet is steamed, the millet is rinsed with cold water to cool down to below 60° C. and then put into a colloid mill for grinding to obtain millet slurry; In the step S4, the millet liquid after the secondary enzymatic hydrolysis is cooled to room temperature through heat exchange; In the step S5, the room temperature millet liquid is centrifuged through a 100-mesh sieve to obtain an enzymatically hydrolyzed millet liquid; In the step S6, the enzymatic millet liquid is added with corresponding amounts of water and auxiliary materials according to the designed formula, the mixing temperature is 55-65° C., and the stirring time is 15-20 min.

3. The method for preparing enzymolysis millet flour according to claim 1, characterized in that: In the step S1, rinse with cold water three times, drain the water, close the lid and steam for 40-50 minutes.

4. The method for preparing enzymolysis millet flour according to claim 1, characterized in that: In the step S2, the millet is ground to 12±3 meshes using a colloid mill.

5. An enzymatically hydrolyzed millet flour, characterized in that: The millet flour is prepared by the method for preparing enzymatically hydrolyzed millet flour according to any one of claims 1 to 4.

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