Preparation process for corn starch, protein powder and whole glucose powder

Abstract

The present invention belongs to the technical field of deep processing of corn, and provides a preparation process for corn starch, a protein powder and a whole glucose powder. The preparation process comprises: performing different pre-treatments on corn kernels, performing high-pressure grinding and separation to prepare corn starch, performing vacuum continuous low-temperature drying to prepare a corn protein powder, and manufacturing sugar from the prepared corn starch, wherein a continuous concentration and crystallization process is used in the sugar manufacturing process to directly obtain a whole glucose powder. The present invention provides a preparation process for corn starch, a protein powder and a whole glucose powder, which process achieves the aim of preparing sulfur-residue-free corn starch and a sulfur-residue-free corn protein powder with little protein degradation, the aim of preparing corn starch at a high yield, and the aim of producing a whole glucose powder by means of a simple preparation process at a low production cost.

Description

Preparation process of corn starch, protein powder and whole glucose powder Technical Field

[0001] The invention relates to the technical field of corn deep processing, and in particular to a preparation process of corn starch, protein powder and full glucose powder. Background Art

[0002] Corn kernels are obtained from the corn cob. Corn kernels contain 12-16% moisture, 70-72% starch, 8-11% protein, 4-6% fat, 1.2-1.6% ash, and 5-7% fiber. Corn starch is primarily used in the pharmaceutical, food, chemical, and textile industries to produce maltose, high maltose syrup, glucose, modified starch, soluble starch, cyclodextrin, acid starch, oxidized starch, and high fructose syrup. It can also be used as a raw material for enzyme production and fermentation of monosodium glutamate, amino acids, and antibiotics.

[0003] Because the husk, endosperm, starch, and protein of corn kernels are tightly bound together, pure starch cannot be separated through conventional soaking and grinding. Currently, industrial production relies on a sulfur dioxide soaking method. This involves soaking corn in water, adding a certain concentration of sulfur dioxide, and soaking at 50-55°C for approximately 50 hours to completely disperse the protein network. The soaking liquid is then separated, and the corn kernels are then crushed, the endosperm removed, and ground to separate the husks. Finally, a centrifuge is used to separate the corn starch from the zein. The starch is then washed, concentrated, dehydrated, and dried to produce finished corn starch. The sulfur dioxide addition is intended to separate the various components of the corn through complex chemical reactions and to prevent fermentation and deterioration during the prolonged soaking process. This method is a common method for industrial corn starch production. Because corn needs to be soaked in sulfur dioxide for a long time, the corn husk, germ, starch, and protein produced contain a small amount of sulfur dioxide. These products are used in large quantities in food and feed. Sulfur dioxide causes damage to the lungs, cardiovascular system, brain and nervous tissue, liver, kidneys, and reproductive organs of animals. The sulfur dioxide content of corn starch is a limiting indicator. At the same time, the acidity generated by long-term soaking in sulfur dioxide causes starch hydrolysis and loss, resulting in reduced yield. On the other hand, when corn is soaked in sulfur dioxide solution at high temperature for a long time during production, sulfur dioxide is easily volatilized, causing serious corrosion to equipment and factory buildings, and endangering the health of operators. Maintaining high temperature requires higher costs, and the sulfur dioxide wastewater after corn soaking is difficult to treat.

[0004] When corn is soaked for a long time, due to the reducing property of sulfur dioxide, some groups of corn protein react with sulfur dioxide, causing protein degradation. The conventional drying process of corn gluten powder is tube drying and airflow drying. The high temperature will cause changes in the properties of the protein, especially the denaturation of heat-sensitive proteins, affecting the nutritional value of corn protein.

[0005] Glucose, an organic compound with the molecular formula C6H12O6, is the most widely distributed and important monosaccharide in nature. It plays a crucial role in biology, serving as an energy source and metabolic intermediate for living cells, making it the primary energy source for organisms. It is widely used in the confectionery and pharmaceutical industries. Glucose is a crucial food and fermentation raw material. For ease of transportation and storage, industrially produced crystalline glucose is produced in large quantities. Crystallized glucose requires slowly cooling and crystallizing a high-concentration glucose solution over dozens of hours, producing bulk glucose crystals and a mother liquor containing impurities. To directly produce whole glucose powder, the conventional process involves spray drying the solution to produce amorphous particles primarily composed of crystallized glucose. However, spray drying requires large equipment investment, high operating costs, and poor economic efficiency. Consequently, whole glucose powder products are rarely available on the market.

[0006] Therefore, it is necessary to provide a new production process to solve the problems of sulfur residue in various products obtained when preparing corn starch in the prior art, protein degradation in protein powder and low starch yield, as well as the high cost and complicated steps in the preparation of whole glucose powder. Summary of the Invention

[0007] In view of this, the first object of the present invention is to provide a preparation process of corn starch and protein powder, so as to achieve the purpose of preparing corn starch without sulfur residue and corn protein powder without sulfur residue with less protein degradation.

[0008] To achieve the above-mentioned object, the present invention provides a process for preparing corn starch and protein powder, which is characterized by comprising the following steps: (1) pre-treating corn kernels; (2) grinding endosperm slurry under high pressure and then centrifuging to obtain a heavy phase of crude starch milk and a light phase of protein suspension; (3) washing the crude starch milk to obtain pure starch milk and washing water; the washing water is a protein suspension; (4) dehydrating and vacuum drying the protein suspension in steps (2) and (3) to obtain corn protein powder; and (5) drying the pure starch milk in step (3) to obtain corn starch.

[0009] During the starch production process of the present invention, sulfur dioxide does not need to be used, which avoids sulfur residue in starch, improves the quality of starch, ensures the safety of food production, and does not need to add enzymes, which reduces production costs and avoids the generation of enzymatic decomposition by-products. At the same time, no long-term soaking is required, and protein can be separated at the same time. The process is streamlined and efficient, the product is safe, and is suitable for mass production.

[0010] This technical solution adopts a reasonable production process. By physically pre-treating the corn kernels, the long-term soaking of corn in sulfur dioxide solution is abandoned. The shear force and cavitation effect generated by high-pressure grinding are used to break large particles into fine particles. The diameter of more than 95% of the particles is controlled to be 5-30μm. After centrifugation, the light phase is a protein suspension. After dehydration and continuous vacuum low-temperature drying, high-quality protein powder with active ingredients is obtained. Because it does not require soaking in sulfur dioxide, the structure of the protein is not degraded by sulfur dioxide, the structure is more complete and the activity is higher. There is no sulfur residue in the starch and protein powder products, which is safe and environmentally friendly, and has low operating costs. The entire process of obtaining starch and protein powder does not require the use of enzymes, which retains the active ingredients to the greatest extent, avoids the destruction of nutrients, is more efficient, and avoids the production of other byproducts and impurities that increase the difficulty of separation.

[0011] Optionally, the pretreatment in step (1) is to clean the corn kernels, peel and remove the germ to obtain corn endosperm particles containing starch and protein, add water to slurry, and keep it for a certain period of time to obtain endosperm slurry.

[0012] The technical solution adopted by the present invention is to peel and degerminate corn kernels by physical methods. After subsequent process treatment, four products including sulfur-free corn husk, corn germ, corn starch and corn gluten powder can be obtained. Since no sulfur dioxide and enzyme preparations are added, the activity of corn gluten is better and the safety is higher.

[0013] Optionally, the peeling and degerming includes directly crushing the corn kernels with a peeling and degerming machine and then screening them, or first moistening the corn kernels with water, allowing the corn husks and corn germs to absorb water and swell, and then crushing them after separation from the endosperm, and screening the corn husks, corn germs, and corn endosperm according to their different specific gravities to obtain three components; the endosperm containing starch and protein has a crushed particle size of 0.1-2 mm; the crushing equipment includes a double-roller mill, a hammer mill, and a turbine mill.

[0014] The technical solution of the present invention reduces the sulfur dioxide soaking process, ensures product safety and quality, shortens the production cycle by more than 40 hours, reduces the loss of nutrients in corn kernels, reduces energy consumption and equipment occupation; avoids the corrosion of equipment and factory buildings by sulfur dioxide, and reduces the investment in equipment and factory buildings; reduces water use, and reduces wastewater discharge by more than half.

[0015] Optionally, the endosperm containing starch and protein is crushed into particles with a particle size of 0.5-1 mm.

[0016] Optionally, the pulping parameters are: a weight ratio of endosperm to water of 1:1-5, a water temperature of 20°C-60°C, and a holding time of 10-300 minutes.

[0017] Optionally, the pulping parameters are: a weight ratio of endosperm to water of 1:1.5, a water temperature of 30-50° C., and a holding time of 30-60 minutes.

[0018] Optionally, the pretreatment in step (1) is to clean the corn kernels and then crush them, add water and stir them evenly, and then centrifuge them to obtain a light phase liquid of corn germ and corn husk suspension, and the heavy phase is endosperm containing starch and protein, and then add water to slurry, and keep it for a certain time to obtain endosperm slurry; the corn kernels have a particle size of 0.1-3 mm, the weight ratio of corn kernels to water is 1:1-5, the water temperature is 20°C-65°C, and the holding time is 10-300 minutes; the crushing equipment is a hammer mill or a turbine mill.

[0019] The technical solution provided by the present invention can obtain three products, namely, a mixture of corn husks and corn germs, corn starch and corn gluten powder, through pre-treatment of corn kernels, crushing them and then centrifuging them, as well as subsequent processing processes. In addition, since no sulfur dioxide and enzyme preparations are added, sulfur-free corn starch and corn gluten are obtained, and the corn gluten has better activity and higher safety.

[0020] Optionally, the corn kernels have a particle size of 0.1-3 mm, the weight ratio of corn kernels to water is 1:1.5, the water temperature is 30-50° C., and the holding time is 30-60 minutes.

[0021] Optionally, the high-pressure grinding equipment is a ball mill or a homogenizer with a pressure range of 10-30 MPa, and more than 95% of the obtained material particle size is 5-30 μm; the centrifugal equipment is a disc centrifuge or a cyclone separator; the dehydration equipment is one of a disc centrifuge, a horizontal screw centrifuge, a plate and frame filter, and a vacuum filter; the starch drying equipment is an air flow dryer, and the protein drying equipment is a vacuum continuous low-temperature drying equipment.

[0022] Optionally, the pressure range of the high-pressure grinding is 12-25 MPa.

[0023] Optionally, the pressure range of the high-pressure grinding is 15-20 MPa.

[0024] The second object of the present invention is to provide a process for preparing corn starch to achieve higher yield and higher efficiency of corn starch preparation, the specific steps are as follows:

[0025] (1) Cleaning corn kernels and crushing them, adding water to prepare a slurry, and the water-adding ratio is 1:1-5; (2) High-pressure grinding the slurry and centrifuging it to separate the heavy phase into a crude starch milk and the light phase into a suspension; (3) Washing the crude starch milk to obtain pure starch milk and washing water; the washing water is a suspension; (4) Dehydrating the suspensions in steps (2) and (3) and then drying them to obtain corn residue; (5) Drying the pure starch milk in step (3) to obtain corn starch.

[0026] The technical solution of the present invention utilizes corn pulverization followed by slurry preparation, high-pressure grinding, and subsequent centrifugal separation, followed by subsequent processing to produce corn residue and corn starch, primarily a mixture of protein, fiber, and fat. Because the entire contents of the corn kernels are subjected to high-pressure grinding followed by centrifugation, this technical solution achieves a higher starch yield than other technical solutions. The production process is simple and suitable for producing corn starch as the target product. Due to the high protein, fiber, and fat content of the corn residue, it is suitable for use in livestock feed production.

[0027] The third object of the present invention is to provide a preparation process for whole glucose powder, which is simple in preparation process and high in yield, comprising the following steps: preparing corn starch through slurry mixing, liquefaction, saccharification, decolorization, ion exchange, and continuous concentration and crystallization to obtain whole glucose powder;

[0028] The continuous concentration crystallization and the above-mentioned vacuum continuous low-temperature drying both adopt a continuous concentration crystallization device, which includes a continuous concentration crystallization tank and a material receiving tank. The continuous concentration crystallization tank includes a rotating shaft, a propeller blade, a tank body, a heating layer, a driving device, a heat exchanger, and a vacuum pump; one end of the rotating shaft is solid and connected to the driving device, and the remaining rotating shaft is hollow. The hollow part is divided into a lower half and an upper half by a horizontal cross plate. The propeller blade is hollow, and the propeller blade and the rotating shaft are connected at the beginning and end. The beginning connection is in the upper half of the rotating shaft, and the end connection is in the lower half of the rotating shaft. The heat medium enters from the lower half of the rotating shaft and enters the upper half of the rotating shaft through the propeller blade, and Discharged from the upper half; the edge of the propulsion blade is serrated, the tank body is connected to the vacuum pump through a heat exchanger, a feed port is set above the tank body, and a discharge port is set below to discharge the discharge into the receiving tank; the receiving tank includes a discharge auger and a silo, and the silo includes a first silo and a second silo, which are respectively arranged at the two ends of the discharge auger, and a spiral blade and a motor are set in the discharge auger, which transfers the discharge to the silo by forward and reverse rotation. The material to be dried enters from the inlet at one end of the equipment, and is heated, propulsed, and stirred by the propulsion blade with a heating function. The dried or crystallized material is transported from the discharge end through the auger into the silo, and the transition from the vacuum state to the normal pressure state is completed through the conversion of the two silos.

[0029] The technical scheme that the present invention provides adopts continuous concentration crystallization process, is connected with propulsion blade by hollow rotating shaft, keeps heating temperature identical, prevents product from being heated unevenly, adds propulsion blade edge and is serrated, makes the block formed by crushing when drying syrup or albumen powder, directly forms powdered product, avoids forming bulk, high hardness sugar block, follow-up also needs crushing to form icing sugar, greatly improves production efficiency, reduces process, is in place in one step, avoids crushing process and causes icing sugar loss, improves yield. Maintain the pressure in tank body with vacuum pump, be convenient to the concentration crystallization of product at low temperatures, keep the biological activity of albumen on the one hand, reduce the cost of operation on the other hand. The albumen powder and full glucose powder of preparation are owing to adopting continuous concentration process, and the thermal medium of suitable temperature can be selected as a whole in confined space, crystallization and drying at low temperatures, combine the zein prepared without soaking in sulfur dioxide, reduce the impact of protein degradation on protein activity, confined space receiving material reduces the waste of product, improves the yield of product.

[0030] Optionally, the vacuum pump (170) of the continuous concentration crystallization device maintains the pressure of the tank (130) at 0.1-6.7 kPa, and the temperature of the heat medium is at 70-120°C.

[0031] The technical solution of the present invention accelerates the process of syrup concentration and crystallization by selecting a high-temperature medium.

[0032] Optionally, the vacuum pump of the vacuum continuous low-temperature drying equipment maintains the tank pressure at 1-3 kPa, and the temperature of the heat medium is maintained at 40-60°C.

[0033] Optionally, the silo 220 includes a first silo 221 and a second silo 222 , which are respectively disposed at two ends of the discharging auger 210 .

[0034] The above technical solution of the present invention includes at least the following beneficial effects: in the technical solution provided by the present invention, corn kernels do not need to be soaked for a long time and at high temperature, the production cycle is shortened by more than 40 hours, energy consumption is saved, wastewater discharge is reduced, and equipment investment is reduced.

[0035] The starch production process of the present invention does not require the use of sulfur dioxide, thereby avoiding sulfur residue in various products, improving product quality, and ensuring the safety of food and feed raw materials. It also does not require the addition of enzymes, reducing production costs and avoiding the generation of enzymatic decomposition byproducts. Furthermore, it does not require long-term soaking and can simultaneously separate protein. The process is streamlined and efficient, suitable for mass production, and avoids the damage of sulfur dioxide to factory buildings and the production environment.

[0036] The present invention peels and degerminates corn kernels, selects out the endosperm, grinds them under high pressure, and then breaks large particles into small particles by shear force and cavitation effect. After subsequent separation, the obtained protein suspension is dehydrated and then continuously dried in a closed device using a vacuum continuous low-temperature drying device. The low-temperature drying process is completed continuously, and the product has good product safety and high yield. High-quality protein powder with active ingredients retained can be obtained. Since it does not need to be soaked in sulfur dioxide, the protein is not degraded, the product safety is guaranteed, the process is green, environmentally friendly, and the operating cost is low.

[0037] The whole glucose powder of the present invention adopts a continuous concentration crystallization process, so the production efficiency is high, the operation cost is low and the equipment investment is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG1 is a flow chart of a process for preparing starch and protein powder from corn in the prior art;

[0039] FIG2 is a process flow chart of Example 1 of the present invention;

[0040] FIG3 is a process flow chart of Example 2 of the present invention;

[0041] FIG4 is a process flow chart of Example 3 of the present invention;

[0042] FIG5 is a front view of a continuous concentration crystallization device according to the present invention;

[0043] FIG6 is a left view of the continuous concentration crystallization device of the present invention.

[0044] In the figure: 100, continuous concentration crystallization tank; 110, rotating shaft; 120, propulsion blade; 130, tank body; 131, feed port; 132, discharge port; 140, heating layer; 141, heat medium inlet; 142, heat medium outlet; 150, driving device; 160, heat exchanger; 170, vacuum pump; 200, material receiving tank; 210, discharge auger; 220, silo; 221, first silo; 222, second silo. DETAILED DESCRIPTION

[0045] To further clarify the objectives, technical solutions, and advantages of the embodiments of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with Figures 1 to 6 of the embodiments of the present invention. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0046] Example 1

[0047] (1) After cleaning the corn kernels, the corn kernels are moistened with water. The corn husks and corn germs absorb water and swell, and are separated from the endosperm and then crushed. The corn husks, corn germs, and corn endosperm are screened according to their different specific gravities to obtain three components. The endosperm containing starch and protein is crushed using a hammer mill to obtain an endosperm particle size of 0.5 mm. Water is added at a weight ratio of 1:1.2 between the endosperm and water, and the water temperature is maintained at 40°C for 30 minutes to obtain an endosperm slurry.

[0048] (2) Grinding the endosperm slurry under a pressure of 17 MPa, and then centrifuging it using a disc centrifuge to obtain a heavy phase as crude starch milk and a light phase as a protein suspension;

[0049] (3) After washing the crude starch milk, pure starch milk and washing water are obtained. The pure starch milk is dehydrated and dried to obtain starch, and the washing water is a protein suspension;

[0050] (4) Dehydrating the protein suspension in step (2) and step (3) using a disc centrifuge to obtain a protein concentrate, and transporting the concentrate to a vacuum continuous low-temperature drying device for dehydration and drying, and drying to obtain corn gluten powder under the conditions of a tank pressure of 3 kPa and a heat medium temperature maintained at 60°C;

[0051] (5) The pure starch milk in step (3) is subjected to slurry mixing, liquefaction, saccharification, decolorization, ion exchange, and continuous concentration and crystallization to obtain full glucose powder. The conditions for continuous concentration and crystallization are that the tank pressure is 4kPa and the temperature of the heat medium is 100°C. The equipment for continuous concentration and crystallization is the same as the vacuum continuous low-temperature drying equipment, including a continuous concentration and crystallization tank 100 and a material receiving tank 200. The continuous concentration and crystallization tank 100 includes a rotating shaft 110, a propeller blade 120, a tank body 130, a heating layer 140, a driving device 150, a heat exchanger 160, and a vacuum pump 170; one end of the rotating shaft 110 is solid and connected to the driving device 150, and the remaining rotating shaft 110 is hollow inside. The hollow part is divided into a lower half and an upper half by a horizontal cross plate. The propeller The blade 120 is hollow inside, and the connection between the propulsion blade 120 and the shaft 110 is open. The first connection is at the upper half of the shaft 110, and the end connection is at the lower half of the shaft 110. The heat medium enters from the lower half of the shaft 110, enters the upper half of the shaft 110 through the propulsion blade 120, and is discharged from the upper half, heating the feed from the inside; the edge of the propulsion blade 120 is serrated, which is convenient for breaking large pieces of product. The tank body 130 is connected to the vacuum pump 170 through the heat exchanger 160, The pressure in the tank is controlled by a vacuum pump to achieve concentration, drying and crystallization at low temperature. A feed port 131 is provided on the top of the tank body 130, and a discharge port 132 is provided on the bottom to discharge the discharge to the receiving tank 200. A heating layer 140 is provided on the outer side of the lower part of the tank body 130. The heating layer 140 is hollow, and a heat medium inlet 141 is provided on one side and a heat medium outlet 142 is provided on the other side to help increase the temperature. The receiving tank 200 includes a discharge auger 210 and a silo 220. The silo 220 includes a first silo 22 1 and the second silo 222 are respectively arranged at the two ends of the discharge auger 210. The discharge auger 210 is provided with a spiral blade and a motor, which transfers the discharge to the first silo 221 and the second silo 222 by forward and reverse rotation. The material to be dried enters from the inlet at one end of the equipment, and is heated, propulsed and stirred by the propulsion blades with a heating function. The dried or crystallized material is transported from the discharge end through the auger into the silo. The transition from the vacuum state to the normal pressure state is completed through the conversion of the two silos.

[0052] The technical solution provided by the present invention adopts a vacuum continuous low-temperature drying process, which is connected to the propulsion blades through a hollow rotating shaft to maintain the same heating temperature and prevent uneven heating of the product. The edges of the propulsion blades are serrated, which can break up the lumps formed while drying the syrup or protein powder, and directly form a powdered product. A vacuum pump is used to maintain the pressure inside the tank, which facilitates the dehydration and drying of the product at a low temperature, on the one hand maintaining the biological activity of the protein, and on the other hand reducing the operating cost. The discharging auger provided by the present invention transfers the discharged product to two silos respectively by running in forward and reverse directions, completing the conversion of the material between vacuum and normal pressure.

[0053] Example 2

[0054] The corn kernels are cleaned and crushed, water is added and stirred evenly, and then centrifuged using a horizontal screw centrifuge to obtain a light phase liquid of corn germ and corn husk suspension, and a heavy phase of endosperm containing starch and protein. Water is then added to prepare a slurry, and the slurry is kept for a certain time to obtain an endosperm slurry. The corn kernels have a particle size of 1.5 mm, a weight ratio of corn kernels to water of 1:1.4, a water temperature of 50°C, and a holding time of 30 minutes. The crushing equipment is a turbine grinder. The light phase liquid is dehydrated and dried to obtain a corn mixed feed.

[0055] (2) Grinding the endosperm slurry under a pressure of 18 MPa, and then centrifuging it using a cyclone centrifuge to obtain a heavy phase as crude starch milk and a light phase as a protein suspension;

[0056] (3) After washing the crude starch milk, pure starch milk and washing water are obtained. The pure starch milk is dehydrated and dried to obtain starch, and the washing water is a protein suspension;

[0057] (4) The protein suspensions in step (2) and step (3) are dehydrated by a horizontal screw centrifuge and then dried in a vacuum continuous low-temperature drying device, where the tank pressure is 2.5 kPa and the heat medium temperature is maintained at 58°C to form corn gluten powder;

[0058] (5) The pure starch milk in step (3) is subjected to slurry mixing, liquefaction, saccharification, decolorization, ion exchange, and continuous concentration and crystallization to obtain full glucose powder. The conditions for continuous concentration and crystallization are that the tank pressure is 3.3 kPa and the temperature of the heat medium is 110°C. The equipment for continuous concentration and crystallization is the same as the vacuum continuous low-temperature drying equipment, including a continuous concentration and crystallization tank 100 and a material receiving tank 200. The continuous concentration and crystallization tank 100 includes a rotating shaft 110, a propeller blade 120, a tank body 130, a heating layer 140, a driving device 150, a heat exchanger 160, and a vacuum pump 170; one end of the rotating shaft 110 is solid and connected to the driving device 150, and the remaining rotating shaft 110 is hollow inside. The hollow part is divided into a lower half and an upper half by a horizontal cross plate. The propeller The blade 120 is hollow inside, and the connection between the propulsion blade 120 and the shaft 110 is open. The first connection is at the upper half of the shaft 110, and the end connection is at the lower half of the shaft 110. The heat medium enters from the lower half of the shaft 110, enters the upper half of the shaft 110 through the propulsion blade 120, and is discharged from the upper half, heating the feed from the inside; the edge of the propulsion blade 120 is serrated, which is convenient for breaking large pieces of product. The tank body 130 is connected to the vacuum pump 170 through the heat exchanger 160, The pressure in the tank is controlled by a vacuum pump to achieve concentration, drying and crystallization at low temperature. A feed port 131 is provided on the top of the tank body 130, and a discharge port 132 is provided on the bottom to discharge the discharge to the receiving tank 200. A heating layer 140 is provided on the outer side of the lower part of the tank body 130. The heating layer 140 is hollow, and a heat medium inlet 141 is provided on one side and a heat medium outlet 142 is provided on the other side to help increase the temperature. The receiving tank 200 includes a discharge auger 210 and a silo 220. The silo 220 includes a first silo 22 1 and the second silo 222 are respectively arranged at the two ends of the discharge auger 210. The discharge auger 210 is provided with a spiral blade and a motor, which transfers the discharge to the first silo 221 and the second silo 222 by forward and reverse rotation. The material to be dried enters from the inlet at one end of the equipment, and is heated, propulsed and stirred by the propulsion blades with a heating function. The dried or crystallized material is transported from the discharge end through the auger into the silo. The transition from the vacuum state to the normal pressure state is completed through the conversion of the two silos.

[0059] Example 3

[0060] (1) Cleaning corn kernels and crushing them, adding water to prepare a slurry, wherein the corn kernels have a particle size of 1.5 mm, the weight ratio of corn kernels to water is 1:1.5, the water temperature is 35° C., and the holding time is 60 minutes; the crushing equipment is a turbine grinder;

[0061] (2) grinding the endosperm slurry under a pressure of 17 MPa, and then separating it using a cyclone separator to obtain a heavy phase as a crude starch milk and a light phase as a protein suspension;

[0062] (3) After washing the crude starch milk, pure starch milk and washing water are obtained. The pure starch milk is dehydrated and dried to obtain starch, and the washing water is a protein suspension;

[0063] (4) drying the protein suspensions in steps (2) and (3) into corn gluten powder using a vacuum continuous low-temperature drying device at a tank pressure of 3 kPa and a heat medium temperature maintained at 48°C;

[0064] (5) The pure starch milk in step (3) is subjected to slurry adjustment, liquefaction, saccharification, decolorization, ion exchange, and continuous concentration and crystallization to obtain full glucose powder. The conditions for continuous concentration and crystallization are that the tank pressure is 5kPa and the temperature of the heat medium is 105°C. The equipment for continuous concentration and crystallization is the same as the vacuum continuous low-temperature drying equipment, including a continuous concentration and crystallization tank 100 and a material receiving tank 200. The continuous concentration and crystallization tank 100 includes a rotating shaft 110, a propeller blade 120, a tank body 130, a heating layer 140, a driving device 150, a heat exchanger 160, and a vacuum pump 170; one end of the rotating shaft 110 is solid and connected to the driving device 150, and the remaining rotating shaft 110 is hollow inside, and the hollow part is divided into a lower half and an upper half by a horizontal cross plate, and the propeller The blade 120 is hollow inside, and the connection between the propulsion blade 120 and the shaft 110 is open. The first connection is at the upper half of the shaft 110, and the end connection is at the lower half of the shaft 110. The heat medium enters from the lower half of the shaft 110, enters the upper half of the shaft 110 through the propulsion blade 120, and is discharged from the upper half, heating the feed from the inside; the edge of the propulsion blade 120 is serrated, which is convenient for breaking large pieces of product. The tank body 130 is connected to the vacuum pump 170 through the heat exchanger 160, The pressure in the tank is controlled by a vacuum pump to achieve concentration, drying and crystallization at low temperature. A feed port 131 is provided on the top of the tank body 130, and a discharge port 132 is provided on the bottom to discharge the discharge to the receiving tank 200. A heating layer 140 is provided on the outer side of the lower part of the tank body 130. The heating layer 140 is hollow, and a heat medium inlet 141 is provided on one side and a heat medium outlet 142 is provided on the other side to help increase the temperature. The receiving tank 200 includes a discharge auger 210 and a silo 220. The silo 220 includes a first silo 22 1 and the second silo 222 are respectively arranged at the two ends of the discharge auger 210. The discharge auger 210 is provided with a spiral blade and a motor, which transfers the discharge to the first silo 221 and the second silo 222 by forward and reverse rotation. The material to be dried enters from the inlet at one end of the equipment, and is heated, propulsed and stirred by the propulsion blades with a heating function. The dried or crystallized material is transported from the discharge end through the auger into the silo. The transition from the vacuum state to the normal pressure state is completed through the conversion of the two silos.

[0065] Comparative Example 1

[0066] The corn is soaked in water three times its mass, with a sulfur dioxide solution concentration of 0.03% in the water, at a temperature of 50°C for 50 hours. The soaking liquid is separated and crushed to obtain corn germ. The corn fiber is separated by grinding. The corn protein and crude starch milk are separated by centrifugation. The starch is washed and the starch is subjected to conventional sugar-making process to obtain glucose syrup, which is then spray-dried to obtain glucose powder.

[0067] Comparative Example 2

[0068] The corn is soaked in water three times its mass, with a sulfur dioxide solution concentration of 0.04% in the water, at a temperature of 48°C for 45 hours, and the soaking liquid is separated. The corn germ is obtained by crushing, and the corn fiber is separated by grinding. The corn protein and crude starch milk are separated by centrifugation, and the starch milk is obtained after washing, and the starch is obtained after drying.

[0069] Comparative Example 3

[0070] Soak the corn in water three times its mass with a sulfur dioxide solution concentration of 0.05% at 52°C for 42 hours. Separate the soaking liquid and crush it to obtain corn germ. Grind the corn fiber and separate the corn protein by centrifugation.

[0071] test

[0072] 1. Yield test: Using corn kernels of equal mass, corn starch and glucose powder were prepared according to the processes of Examples 1, 2, 3 and Comparative Example 1, and the yields were obtained. See Table 1

[0073] The technical solution provided in the present invention, by pretreatment, high pressure grinding, continuous concentration and crystallization and other continuous processes, the starch yield prepared in Example 1 can reach 69.5%, the starch yield prepared in Example 2 can reach 71.0%, and the starch yield prepared in Example 3 can reach 72.5%, and the starch yield of Example 3 is higher than the yield of 71.8% of the starch in Comparative Example 1. And among Examples 1 to 3, the starch yield of Example 3 is the highest, and it can be seen that the technical solution provided in Example 3 is applicable to the process requirements of the corn starch of the target product. The protein powder yields prepared in Examples 1 and 2 of the present invention are 8.1% and 7.9%, both higher than the protein powder yield of Comparative Example 1, 5.8%.

[0074] Sulfur Residue Test: Starch and protein powder were prepared using the same mass of corn kernels as in Example 1 and Comparative Example 2, respectively. Each process was repeated five times. The resulting starches were then tested for sulfur dioxide residue. The sulfur residue in the starch and protein powders was determined using the iodine titration method. The results are shown in Table 2.

Claims

1. A process for preparing corn starch and protein powder, characterized in that: The following steps are involved: (1) Pre-treating corn kernels; (2) The endosperm slurry is high-pressure ground and then centrifuged to separate the heavy phase into crude starch milk and the light phase into protein suspension; (3) washing the crude starch milk to obtain pure starch milk and washing water, wherein the washing water is a protein suspension; (4) dehydrating the protein suspension in step (2) and step (3) and performing vacuum continuous low-temperature drying to obtain corn gluten powder; (5) The pure starch milk in step (3) is dried to obtain corn starch.

2. The preparation process of corn starch and protein powder according to claim 1, wherein The pretreatment in step (1) is to clean the corn kernels, peel and remove the germ to obtain corn endosperm particles containing starch and protein, add water to slurry, and keep it for a certain period of time to obtain endosperm slurry.

3. The preparation process of corn starch and protein powder according to claim 2, characterized in that, The peeling and degerming process includes directly crushing the corn kernels with a peeling and degerming machine and then screening them, or first wetting the corn kernels with water, allowing the corn husks and corn germs to absorb water and swell, separating them from the endosperm and then crushing them, and screening the corn husks, corn germs, and corn endosperm according to their different specific gravities to obtain three components; the endosperm containing starch and protein has a crushed particle size of 0.1-2 mm; and the crushing equipment includes a double-roller mill, a hammer mill, and a turbine mill.

4. The preparation process of corn starch and protein powder according to claim 2, wherein The pulping parameters are as follows: the weight ratio of endosperm to water is 1:1-5, the water temperature is 20°C-60°C, and the holding time is 10-300 minutes.

5. The preparation process of corn starch and protein powder according to claim 1, wherein The pretreatment in step (1) is to clean the corn kernels and then crush them, add water and stir them evenly, and then centrifuge them to obtain a light phase liquid of corn germ and corn husk suspension, and a heavy phase of endosperm containing starch and protein, and then add water to make a slurry, and keep it for a certain time to obtain an endosperm slurry; the particle size of the corn kernels is 0.1-3 mm, the weight ratio of corn kernels to water is 1:1-5, the water temperature is 20°C-65°C, and the holding time is 10-300 minutes; the crushing equipment is a hammer mill or a turbine mill, and the centrifugal equipment is a horizontal screw centrifuge, a cyclone centrifuge, a disc centrifuge, etc.

6. The preparation process of corn starch and protein powder according to claim 1, wherein The high-pressure grinding equipment is a ball mill or a homogenizer with a pressure range of 10-30 MPa, and the obtained liquid particle size is more than 95% of 5-30 μm; the centrifugal separation equipment is a disc centrifuge or a cyclone separator; the dehydration equipment is one of a disc centrifuge, a horizontal screw centrifuge, a plate and frame filter, and a vacuum filter; the starch drying equipment is an air flow dryer, and the protein drying equipment is a vacuum continuous low-temperature drying equipment.

7. A process for preparing corn starch, characterized in that: The following steps are involved: (1) Clean the corn kernels and crush them, then add water to make a slurry with a water-to-water ratio of 1:1 to 5; (2) The slurry is high-pressure ground and then centrifuged to separate the heavy phase into a crude starch milk and the light phase into a suspension; (3) washing the crude starch milk to obtain pure starch milk and washing water; the washing water is a suspension; (4) dehydrating and drying the suspensions in steps (2) and (3) to obtain corn residue; (5) The pure starch milk in step (3) is dried to obtain corn starch.

8. A process for preparing full glucose powder from corn starch as described in any one of claims 1 to 7, characterized in that, The following steps are involved: The corn starch is subjected to slurry adjustment, liquefaction, saccharification, decolorization, ion exchange, and continuous concentration and crystallization to obtain full glucose powder.

9. The process for preparing full glucose powder from corn starch according to claim 8, wherein The continuous concentration crystallization device comprises a continuous concentration crystallization tank (100) and a material receiving tank (200), wherein the continuous concentration crystallization tank (100) comprises a rotating shaft (110), a propulsion blade (120), a tank body (130), a heating layer (140), a driving device (150), a heat exchanger (160), and a vacuum pump (170); one end of the rotating shaft (110) is solidly connected to the driving device (150), and the remaining rotating shaft (110) is hollow inside, and the hollow part is divided into a lower half and an upper half by a horizontal cross plate; the propulsion blade (120) is hollow inside, and the propulsion blade (120) and the rotating shaft (110) are open at the beginning and end connection, wherein the beginning connection is at the upper half of the rotating shaft (110), and the end connection is at the lower half of the rotating shaft (110); the heat medium is discharged from the rotating shaft (110) to the upper half of the rotating shaft (110); The liquid enters the lower half of the shaft (110), enters the upper half of the rotating shaft (110) through the propulsion blade (120), and is discharged from the upper half; the edge of the propulsion blade (120) is serrated, the tank body (130) is connected to the vacuum pump (170) through the heat exchanger (160), the tank body (130) is provided with a feed port (131) on the top, and a discharge port (132) on the bottom to discharge the discharge into the receiving tank (200); the receiving tank (200) includes a discharge auger (210) and a silo (220), the silo (220) includes a first silo (221) and a second silo (222), which are respectively provided at the two ends of the discharge auger (210), and a spiral blade and a motor are provided in the discharge auger (210), which transfers the discharge to the silo (220) by forward and reverse rotation.

10. The production process for preparing full-glucose powder from corn starch according to claim 9, wherein The vacuum pump (170) of the continuous concentration crystallization device maintains the pressure of the tank (130) at 0.1-6.7 kPa, and the temperature of the heat medium is at 70-120°C.

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