Method for processing corn by means of pressurized soaking process

Abstract

The present invention relates to a method for deeply processing corn by means of a pressurized soaking process, and in particular to a method for preparing dextrin, syrup, or sugar. The soaking process of the traditional wet corn processing process is replaced with the pressurized soaking process, so that corn can quickly absorb water and expand without damaging the germ and endosperm quality and discharging wastewater and waste gas, thereby meeting process requirements of the wet corn processing process. Further, the corn is de-germinated and dehulled, and the obtained germs and corn hulls are refined to respectively meet commercial sale standards; a corn slurry material obtained after de-germination and dehulling directly undergoes slurry preparation and liquification. The resulting liquified liquid can be dried to produce dextrin, or further saccharified, refined, and concentrated to produce syrup, or optionally further processed to produce sugar.

Description

Method for processing corn by pressure steeping Technical Field

[0001] The present invention relates to the technical field of corn deep processing, in particular to a production method for preparing dextrin, syrup or sugar by deep processing corn using a pressure soaking method, wherein germ, protein and corn husk (fiber) are also produced. Background Art

[0002] Corn is the primary raw material for the production of dextrin, syrup, or sugar. After being purified through well-known processes, corn is processed using traditional wet processing methods, including soaking in sulfurous acid, degerming, dehulling, starch washing and refining, liquefaction, saccharification, refining, and concentration to produce syrup or sugar (or dextrin). However, the long soaking in sulfurous acid not only produces a large amount of soaking water that requires treatment, but also emits a large amount of "odor" that pollutes the environment during the production process. To reduce the emission of wastewater and exhaust gas, improvements have been made to the process.

[0003] CN102464723A discloses a composite corn soaking method for producing corn starch, which is characterized by: first, adding a sulfurous acid solution with a concentration of 0.15%-0.20% to the corn to be soaked, covering the corn by 20-30 cm; second, adjusting the pH value of the soaking solution with a 15% sodium hydroxide solution to control the pH value within the range of 4.5-5.0; and third, heating the soaking solution to 50°C, adding cellulase with an enzyme activity of 40,000 U at a ratio of one hundred thousandth of the dry matter of the corn, and soaking the corn at a constant temperature of 50°C for 24 hours. Although this application reduces the amount of sulfurous acid used and reduces the soaking time from 48 hours to 24 hours, it does not fundamentally solve the waste gas and wastewater problems, the soaking time is too long, and the efficiency is low.

[0004] CN101372702A discloses a method for shortening the soaking time of corn for starch production, which is characterized by: 1. Pre-treating before soaking: selecting corn with plump grains, no insect infestation, and no mildew, washing it three times with water, draining it, leaving it overnight, and placing it in a reactor; 2. Soaking: adding drinking water, 450-1350 IU / g corn protease, and 15-80 IU / g corn cellulase in a ratio of 1-3 / 1 by mass of corn; 3. Pressurizing: connecting compressed air to 0.1-0.5 MPa, heating the reactor jacket with steam at 30-60°C for 10-20 hours. This method uses protease and cellulase instead of sulfite, solving the problems of sewage and waste gas. However, the use of protease and cellulase increases costs and produces a large amount of water-soluble protein in the system, which increases the burden on subsequent sugar refining. Furthermore, the soaking time of 10-20 hours is still too low in efficiency.

[0005] CN115666258A discloses corn sweetening steeping, which is characterized by: a method for producing a soluble starch hydrolysate or hydrolyzed starch syrup from corn kernels, the method comprising soaking substantially intact corn kernels in water at a temperature at or above the gelatinization temperature of the starch in the corn kernels, wherein the soaking is carried out in the presence of an exogenous heat-stable α-amylase, which produces a soluble starch hydrolysate or hydrolyzed starch syrup from the starch present in the corn kernels, and the soaking temperature inactivates endogenous corn proteases and carbohydrate hydrolases present in the corn kernels; and subsequently fractionating the soaked corn kernels to obtain a soluble starch hydrolysate or hydrolyzed starch syrup portion and a substantially intact, starch-depleted, protein- and oil-enriched corn kernel residue, wherein the process has a low starch sugar yield, requires special equipment for the production process, and is difficult to industrialize.

[0006] The second is a process for producing sugar or syrup using a semi-dry corn process. CN115807136 A discloses a semi-dry corn germ and husk extraction process for converting low-fat grits into glucose syrup, which is characterized by comprising the following steps: Step 1: Tempering and moistening the grain: The cleaned corn is conveyed to a paddle steam homogenizer, where 1-2% steam is added per ton of corn at a steam pressure of 0.4 MPa, and 1% room-temperature water is added. The steam and water are injected with an intelligent moisture meter for measurement and control. The homogenized corn is then fed into a tempering bin. After tempering for 4 hours, it is best if the germ becomes flexible and the husk and endosperm are easily separated. Step 2: Kneading and degerming: The tempered corn from Step 1 is fed into a kneading and degerming machine for kneading and degerming, so that the corn is rubbed into four, six, or eight petals. The embryo is intact without being broken, and the seed coat is peeled off by more than 70%; Step 3: Screening and grading: the material in step 2 is fed into a high-square grading screen for screening. According to the particle density of the material, the material is graded and screened into eight kinds of materials: 4 mesh, 4-6 mesh, 6-8 mesh, 8-12 mesh, 12-24 mesh, 24-40 mesh, 40-60 mesh, and 60 mesh. Step 4: Material peeling: the eight kinds of materials prepared in step 3 are fed into a peeling machine respectively, and the corn husks in the eight kinds of materials are removed by graded air volume and graded peeling; Step 5: Material separation: the eight kinds of materials in step 4, including the two kinds of materials of 4-6 mesh and 6-8 mesh, are passed through an embryo selection machine. The raw germ and raw endosperm are selected, the raw germ is rubbed by a germ rubbing machine, and then color-sorted by a color sorter to obtain pure germ, and the raw endosperm is color-sorted by a color sorter to obtain high-purity endosperm, so that the germ and endosperm are purified; Step 6: Endosperm crushing: The endosperms of different particle sizes obtained in Step 5 are passed through a pelletizer, a high-square plansieve, and a compound powder purifier, and are pelletized, screened, and powdered to remove some skins and broken germs to obtain purified endosperm; Step 7: Endosperm purification: The endosperms of different particle sizes obtained in Steps 5 and 6 are further selected by a skin suction machine and a color sorter to remove skins and trace broken germs to obtain pure endosperm in equal and different diameters; Step 8: Grinding and flour making: The pure endosperm obtained in step seven is subjected to four series grinding in an 8-roller mill to grind into 40-mesh corn flour, and then the fine metal particles are removed by a magnetic separator and a metal detector; Step nine: Preparation and preparation: The material obtained in step eight is added with edible water in a mass ratio of 1:2.3 for slurrying, and then transferred to a colloid mill for grinding, and then through saccharification, liquefaction, and protein extraction processes to finally produce glucose syrup. Although this method eliminates the soaking process of the corn wet processing method, steam moistening and heat preservation and conditioning still consume a large amount of steam. The multiple air separation, peeling, and germ removal processes are complicated, the equipment and infrastructure investment is large, and the process stability is poor.

[0007] The third method is to use steam explosion to replace the corn soaking process. CN101607218A discloses the use of steam explosion technology to separate the corn germ, endosperm and seed coat: 1. Soak the corn until the water content is 30%; 2. The steam explosion pressure is 1.0-1.5MPa and the time is 3-6 minutes. This method uses 1.0-1.5MPa steam to act on the corn, causing the germ to denature and the endosperm to gelatinize. Special equipment needs to be developed to further process the denatured germ and gelatinized endosperm.

[0008] Fourth, corn is directly liquefied and saccharified without starch process. CN104630310A discloses a production method of glucose from crushed corn, which is characterized by comprising the following steps: 1) impurity removal: removing impurities in crushed corn; 2) crushing: crushing corn into corn flour particles with a particle size of 100% passing through a 60-mesh sieve; 3) slurry preparation: putting corn flour particles into a slurry preparation tank, adding evaporation condensate and stirring to form a corn starch slurry with a dry matter concentration of 40%; 4) sand removal: removing fine sand and gravel in the slurry; 5) slurry preparation: adding evaporation condensate to make the dry matter content of the slurry reach 30%, and adding NaCO3 to adjust the pH value to 5-7, and at the same time pressing the slurry. 6) Jet liquefaction: The material in the starch slurry tank is pumped into the jet liquefier with a pump. The jet liquefaction temperature is controlled at 108°C. The liquefied material enters the retention tube and the liquefaction column successively and is maintained at 95°C for liquefaction for 3 hours. The DE value of the liquefied liquid is controlled at 10%-15%; 7) Filtration: The qualified liquefied liquid after liquefaction is filtered through a plate and frame filter. The filtered liquefied liquid enters the saccharification tank for saccharification; 8) Saccharification: The pH of the liquid is adjusted to 4.2-4.5 with hydrochloric acid, and the temperature is rapidly lowered to 62°C. Then, saccharifying enzyme is added for saccharification. The saccharification time is greater than 40 hours. After 1 hour, when no dextrin is detected and the DE value is greater than 95%, saccharification is terminated and the pH of the material is adjusted to 4.8-5.5 before entering the filter tank; 9) Filtration: Before filtration, the material temperature is reduced to below 60°C, and the plate and frame filter is pre-coated with diatomaceous earth for filtration to filter out the denatured flocculated protein solids contained in the material, and the material enters the decolorization tank; 10) Decolorization: The sugar solution is pumped into the plate and frame that has been pre-coated with activated carbon for decolorization. During decolorization, the valve is opened to allow the decolorized sugar solution to enter the decolorization process; 11) Decolorization: The decolorized sugar solution is first pumped into the regenerated positive column by the pump, and the flow rate of the sugar solution can be controlled to be the resin volume per hour. The sugar solution exits the positive column and enters the negative column. The conductivity of the sugar solution exiting the negative column is controlled to be less than 50 μS / cm, and the pH is controlled to be between 4.5 and 6.0. In this way, the ionic impurities and ionic pigments contained in the sugar solution are removed, and the qualified sugar solution enters the evaporation feed tank. 12) Evaporation concentration: The sugar solution after separation is pumped into a 5-effect negative pressure evaporation system for concentration. The concentration is controlled at 70%-75%. The sugar solution with a qualified concentration is pumped into the finished product tank for storage. This method does not remove the germ or peel. The precious corn oil not only fails to generate value, but also circulates in the liquefaction, saccharification, and refining systems. Removing oil from the glucose syrup requires higher refining costs.

[0009] Therefore, it is of great practical significance to find a new process that produces sugar slurry or sugar without the traditional soaking process or starch process, and produces high-quality germ, corn husk (fiber) and protein, with a simpler process flow, less investment and land occupation, lower energy consumption and operating costs, and basically no wastewater or exhaust gas discharge. Summary of the Invention

[0010] The present invention aims to provide a method for deep processing corn using a pressure soaking method, particularly for preparing dextrin, syrup or sugar. The pressure soaking method replaces the soaking process of a conventional wet corn processing method, thereby allowing the corn to rapidly absorb water and swell without damaging the quality of the germ and endosperm and without discharging wastewater or waste gas, thereby meeting the process requirements of the wet corn processing method. The corn is then further degermed and dehusked (i.e., defibered), and the resulting germ and husk are refined to meet commercial sale standards. The degermed and dehusked corn slurry is directly slurried, liquefied, dried, and used to produce dextrin. Alternatively, the resulting liquefied liquid is further treated, saccharified, refined, and concentrated to produce syrup or, optionally, sugar.

[0011] Specifically, the present invention relates to a method for deep processing corn using a pressure soaking method, in particular for preparing dextrin, syrup or sugar, comprising the following steps:

[0012] (1) adding corn slurry and optional chemical additives continuously or in batches to a pressurized soaking reactor; reacting in the reactor at a reaction temperature of 20-70° C. and a gauge pressure of 0.1 MPa or more for more than 0.5 hour, and discharging the materials continuously or intermittently to obtain a water-containing corn slurry A;

[0013] (2) removing the germ from the corn slurry A in step (1) to obtain corn slurry B and germ;

[0014] (3) defibering the corn slurry B in step (2) to obtain corn slurry C and corn husks;

[0015] (4) The corn slurry C in step (3) is directly slurried and liquefied, and the solids are separated from the liquefied liquid after liquefaction, and the solids are further processed to obtain protein;

[0016] (5) The liquefied liquid after the solids are separated in step (4) is dried to obtain dextrin, or the liquefied liquid is further saccharified to obtain syrup, and the syrup is optionally further crystallized to obtain sugar.

[0017] Preferably, the moisture content of corn in the obtained corn slurry A is greater than or equal to 35 wt %, more preferably greater than or equal to 38 wt %, and even more preferably greater than or equal to 40 wt %.

[0018] In one embodiment, the corn is first washed with water to remove impurities on the surface of the corn, such as dust, and optionally separated to remove empty kernels and large and small corn debris, such as corn cobs, corn stalks, stones, etc., as well as gloves, bricks, iron blocks, etc., and preferably drained.

[0019] The water is, for example, selected from drinking water, deionized water, or recycled process water. Preferably, the amount of water added is 20-300 wt %, more preferably 50-250 wt %, even more preferably 70-200 wt %, further more preferably 90-150 wt %, for example, 100 wt %, 110 wt %, and 120 wt %, based on the dry weight of the corn.

[0020] Preferably, in the reactor, the reaction temperature is 40-70°C, more preferably 45-65°C, such as 50°C, 60°C and 63°C.

[0021] Preferably, in the reactor, the gauge pressure of the reaction is 0.1-10 MPa, more preferably 0.5-8 MPa, still more preferably 0.5-6 MPa, such as 1 MPa, 1.2 MPa, 2 MPa and 6 MPa.

[0022] Preferably, in the reactor, the reaction time is 0.5-10 hours, more preferably 0.5-8 hours, still more preferably 0.5-6 hours, such as 1, 2, 3 and 4 hours.

[0023] In one embodiment, a suitable gas or water that does not affect the reaction, such as air, nitrogen, oxygen and / or water, is introduced into the reactor to increase the pressure of the reactor, while water vapor is not a suitable gas.

[0024] In one embodiment, in addition to corn and water, a chemical additive is added to the reactor. The chemical additive may be an acid, a base (including a Lewis acid or a base) or an enzyme, such as citric acid, acetic acid, oxalic acid, sulfuric acid, hydrochloric acid, sodium sulfite, etc. Preferably, the amount of the chemical additive is 0-10% by weight, more preferably 0-1.5% by weight, and even more preferably 0-1% by weight, such as 0, 0.5% by weight and 1% by weight, based on the dry weight of the corn.

[0025] The pressurized immersion reactor is one or more pressure vessels such as a pressure autoclave, a pressure tank, a tubular reactor, a digester (pot), a pressure screw conveyor, a tower, a steam ball, an autoclave, a decomposition pot, a vulcanizing tank, etc., which can be used alone or in series or in parallel.

[0026] In step (2), degermination can be performed by further crushing the corn in the corn slurry A obtained in step (1), for example, by using a cam mill, and then separating the germ using a cyclone.

[0027] In step (3), defibration can be performed as follows: the corn slurry B after degermination in step (2) is further crushed, for example, by grinding it in a fine mill, and then defibering it by using a zigzag screen. The fine mill is, for example, a pin mill, and the zigzag screen is, for example, a pressure zigzag screen.

[0028] In step (4), the corn slurry C after the removal of germ and fiber is preferably concentrated (optionally washed and desalted) to a water content of 40-70% by weight, preferably 50-70% by weight, using a filter, such as a vacuum drum filter, or a centrifuge; the starch refining process, for example, refers to centrifugation and starch washing; the slurry adjustment temperature is preferably 60-65°C, and the pH is preferably 5.5-6; the liquefaction is performed, for example, by spraying, and the liquefaction process here can be a single spray or a double spray, or it can also be gentle liquefaction at 76-100°C, wherein a liquefaction enzyme (such as a high-temperature liquefaction enzyme) is added, and the liquefaction enzyme can be added once or twice, preferably twice, and its addition amount is preferably 0.1-0.5 kg / ton of dry corn starch; the DE value of the liquefied liquid is preferably controlled to be 14-18, and after the liquefaction meets the standard, the liquefied liquid is separated from solids (such as protein), for example, by a filter.

[0029] The liquefied liquid after the solids are separated in step (5) can be dried to obtain dextrin, or the pH value of the liquefied liquid is preferably adjusted to 4.0-4.4, preferably 4.0-4.2; the further treatment includes, for example, filtration, decolorization, ion exchange, and concentration; the sugar is preferably glucose; the DE value of the saccharified liquid after saccharification is preferably 95-98, for example, 96.7.

[0030] The saccharification in step (5) is performed, for example, by adding saccharifying enzyme, the amount of which added is, for example, 0.01-0.03 wt%, such as 0.022 wt%, based on dry corn starch.

[0031] The solid matter includes protein, for example.

[0032] For example, one embodiment of the corn processing method of the present invention includes the following steps:

[0033] Step 1: Wash the corn with water (e.g., drinking water or recycled process water) to remove dust from the surface of the corn, remove the shrunken kernels and large and small corn debris, and drain the water;

[0034] Step 2: Weigh the corn treated in step (1) and 20-300 wt% of water based on the dry weight of the corn, and add them continuously or in batches into a pressure soaking reactor. React in the reactor at 20-70° C. and 0.1-10 MPa for 0.5-10 hours, and discharge continuously or in batches into a normal pressure tank to obtain a water-containing corn slurry A.

[0035] Step 3, crushing and extracting germ: The corn slurry A obtained in step 2 still contains a certain amount of corn kernels, which are crushed by a convex tooth mill and the germs are extracted by a cyclone to obtain corn slurry B. The crushing can be performed in a primary stage to extract the germs, or in a secondary stage to extract the germs. The extracted germs are washed, squeezed, and dried to obtain the germs.

[0036] Step 4, fine grinding to remove corn husks (fiber): The corn slurry B from which the germ has been removed in step 3 is transported to fine grinding, where the corn particles are further crushed and the corn husks are screened out. A first-stage fine grinding and first-stage peeling or a second-stage fine grinding and second-stage peeling can be performed to obtain corn slurry C. The removed corn husks (fiber) are washed, squeezed, and dried to obtain corn husks.

[0037] Step 5: Concentrating the corn slurry C in step 4: Concentrating the corn slurry to a water content of 40-70% by weight using a centrifuge or filter. Preferably, a vacuum drum filter is used for concentration and washing and desalination to obtain corn slurry D. Preferably, a ZD70 self-unloading vacuum drum filter manufactured by Changchun Meichuan Machinery Manufacturing Co., Ltd. is recommended.

[0038] Step 6, dextrin, syrup, sugar and protein preparation: the pH value of the corn slurry D in step 5 is adjusted to 5.6-5.8, 0.01-0.03 weight % of high temperature liquefaction enzyme based on the corn starch dry weight is added, and pre-liquefaction is stirred at 60-65 ℃ for half an hour; the corn slurry adjusted is instantly heated to 76-100 ℃, stirred and liquefied for 10-30 minute, or sprayed at 102-108 ℃, cooled to 90-95 ℃, and then liquefied for 90-120 minute; the DE value of the control liquefied liquid is 14-18, the iodine test is qualified, filtered, and solids (filter cake) are filtered out to obtain clarified liquefied liquid, which can be dried to obtain dextrin; or syrup is obtained after the saccharification of the liquefied liquid, for example, glucose syrup (the syrup DE value is preferably 95-98, for example, 96.7), or further crystallized to obtain sugar, for example glucose; and protein is obtained after the washing and drying of the filter cake.

[0039] The liquefied liquid is saccharified by, for example, adjusting the pH (eg, 4.0-4.2) and temperature (eg, 60-63° C.), adding a saccharifying enzyme, and then saccharifying and refining to obtain a syrup.

[0040] Another object of the present invention is to provide a syrup obtained by the method of the present invention.

[0041] Another object of the present invention is to provide sugars obtained by the method of the present invention.

[0042] Another object of the present invention is to provide dextrin obtained by the method of the present invention.

[0043] Another object of the present invention is to provide embryos obtained by the method of the present invention.

[0044] Another object of the present invention is to provide corn husks obtained by the method of the present invention.

[0045] Another object of the present invention is to provide a protein obtained by the method of the present invention.

[0046] The content in this application is determined as follows:

[0047] (1) Determination of moisture content of corn after soaking

[0048] Take the soaked corn and wipe off any surface moisture with absorbent paper. Weigh 3-5g of the corn and place it in a METTLER TOLEDO halogen moisture analyzer to quickly measure the moisture content.

[0049] (2) Determination of soluble organic matter content in clarified soaking water

[0050] 20ul of clarified soaking water was extracted and injected into a Waters 1515 liquid chromatograph to measure the water-soluble sugar of each component; another 20ul of clarified soaking water was injected into a TOC-L total carbon / total nitrogen analyzer to analyze the total nitrogen and convert the protein content. The sugar content of each component was added together with the protein content to obtain the soluble organic matter content.

[0051] (3) Determination of protein content in organic matter in clarified liquid

[0052] Extract 20ul of clarified soaking water and inject it into TOC-L total carbon / total nitrogen analyzer to analyze the total nitrogen, which is multiplied by a fixed coefficient of 6.25 to obtain the protein content.

[0053] Features of the present invention

[0054] (1) Using the pressurized soaking method instead of the traditional wet corn processing method can shorten the soaking time from the original 36-48 hours to 0.5-10 hours. For example, if the annual processing capacity is 500,000 tons of corn, the soaking tank volume will be reduced from 10*350m 3 Reduced to 2*300m 3 , the investment in soaking equipment is saved by at least 80% (for example, in one embodiment, the equipment investment is reduced from 19 million yuan to 3 million yuan); the soaking of the present invention does not use sulfurous acid, does not generate wastewater and odor, and the soluble organic matter content of the soaking water is reduced from 7.8-10 weight%, and the soluble protein content in the organic matter is reduced from 3.6-5 weight%, to 0.05-1.5 weight% and 0.15-0.35 weight%, respectively. After the soaking water is desanded by cyclone, it enters the crushing process with the corn, eliminating the soaking water concentration and evaporation process, saving a large amount of steam.

[0055] (2) The corn slurry after degerming and defibering is directly liquefied into sugar without going through the starch process, which eliminates the starch processes such as 3-stage centrifugal concentration to remove protein and 12-stage starch washing, saves at least about 26% of equipment investment, and also reduces the costs of electricity consumption, water consumption, and equipment maintenance.

[0056] The method of the present invention, which utilizes a pressure soaking method for deep processing of corn, particularly for preparing dextrin, syrup, or sugar, can reduce investment by approximately 52% (based on 500,000 tons of corn per year) and production costs by more than 33%. The dextrin, syrup, sugar, protein, germ, and fiber produced using the method are superior in quality to those produced using a wet process, with the protein content increasing from 55-60% by weight in the wet process to 62-70% by weight. The yield of deep-processed corn products per unit (dry basis) is higher, with the dextrin (or starch) yield increasing from 70% by weight in the wet process to 73-74% by weight, the protein yield increasing from 5.5% by weight to 7.0-7.5% by weight, the germ yield slightly increasing, and the fiber yield remaining the same as the wet process. Due to the average increase in dextrin (or starch) yield of approximately 4% by weight and the average increase in protein yield of approximately 1.8% by weight, the revenue per ton of dry basis corn increases by 236 yuan. Therefore, the method is not only safe and environmentally friendly, but also offers lower investment and costs, and higher revenue per unit of dry basis corn. DETAILED DESCRIPTION

[0057] Example

[0058] The technical solution of the present invention will be further described below in conjunction with embodiments. The embodiments of the present invention should not be construed as limiting the present invention. Those skilled in the art will recognize that various modifications, variations, and combinations of the embodiments of the present invention may be made without departing from the scope of protection of the present invention, and that such modifications, variations, and combinations are considered to be within the scope of original thought.

[0059] Example 1

[0060] Step 1: Wash corn (water content 10.44% by weight) with drinking water to remove dust from the surface of the corn, remove shriveled kernels and large and small corn debris from the corn, and drain the water;

[0061] Step 2: Weigh 2 kg of the corn purified in step 1, add it to a 10-liter autoclave, add 2.2 kg of water, add 20 g of commercially available citric acid, raise the temperature to 60-63° C., increase the air pressure to 1 MPa, and react for 1 hour. Discharge it into a normal pressure tank to obtain corn slurry A. The moisture content of the corn is measured to be 38.58% by weight, the soluble organic matter in the clarified soaking water is 0.86% by weight, and the protein content in the organic matter is 0.25% by weight;

[0062] Step 3: Crushing and Germ Extraction: The corn slurry A from step 2 still contains a certain amount of corn kernels, which are crushed using a convex tooth mill and the germs are extracted using a cyclone to obtain corn slurry B. This process uses two-stage crushing and two-stage germ extraction. The extracted germ is washed, squeezed, and dried using known processes to obtain the germ.

[0063] Step 4: Fine Grinding to Remove Husks: The corn slurry B obtained in step 3 is transferred to a pin mill, where the corn particles are further broken down and the husks are screened out using a pressure sieve to obtain corn slurry C. This process involves a first-stage fine grinding and a first-stage husk removal. The removed husks (fiber) are washed, squeezed, and dried using known processes in the industry to obtain corn husks.

[0064] Step 5: Washing and concentrating the corn slurry C obtained in step 4: Washing and desalting the corn slurry C using a vacuum drum filter, and concentrating the corn slurry to a water content of 70% by weight to obtain corn slurry D;

[0065] Step 6, slurry adjustment, liquefaction, and saccharification: The pH of the corn slurry D obtained in step 5 is adjusted to 5.6-5.8. 0.015% by weight of a high-temperature liquefaction enzyme, based on the dry weight of the corn starch, is added at once and pre-liquefied at 60-65°C for half an hour with stirring. The adjusted corn slurry is spray-liquefied at 108°C for 30 minutes. The temperature is then lowered to approximately 95°C and liquefied for an additional 90 minutes. The DE value of the liquefied liquid is controlled to be between 14-18 and passes the iodine test. The liquefied liquid is filtered to remove solids such as protein to obtain a clear liquefied liquid. The DE value of the liquefied liquid is measured to be 16.74, and the filter cake passes the iodine test for free starch. The pH of the liquefied liquid was adjusted to 4.0-4.2, the temperature was lowered to about 61° C., 0.022 wt % of saccharifying enzyme based on dry corn starch was added, and the mixture was kept warm and saccharified for 48 hours to obtain a saccharified liquid with a DE value of 96.7 and a protein content of 67.8 wt %. The quality of the germ and fiber was the same as that of the wet process. The yield (dry basis) was detected as follows: sugar yield 78.24 wt %, protein yield 7.34 wt %, germ yield 8.09 wt %, and fiber yield 10.44 wt %.

[0066] Example 2

[0067] Step 1: Wash corn (water content 15.15% by weight) with drinking water to remove dust from the surface of the corn, remove the empty kernels and large and small corn debris from the corn, and drain the water;

[0068] Step 2: Weigh 2 kg of the purified corn in step 1, add it to a 10-liter high-pressure tubular reactor, add 2.2 kg of water, raise the temperature to 50° C., increase the air pressure to 6 MPa, and react for 3 hours. Unload the material into a normal pressure tank to obtain corn slurry A. The moisture content of the corn is measured to be 41.42% by weight, the soluble organic matter in the clarified soaking water is 1.00% by weight, and the protein content in the organic matter is 0.34% by weight.

[0069] Step 3: Crushing and Germ Extraction: The corn slurry A from step 2 still contains a certain amount of corn kernels, which are crushed using a convex tooth mill and the germs are extracted using a cyclone to obtain corn slurry B. This process uses two-stage crushing and two-stage germ extraction. The extracted germ is washed, squeezed, and dried using known processes to obtain the germ.

[0070] Step 4: Fine Grinding to Remove Husks (Fiber): The corn slurry B obtained in step 3 is transferred to a pin mill, where the corn particles are further broken down. The husks are then screened out using a pressure sieve to obtain corn slurry C. A first-stage fine grinding and first-stage peeling process is employed. The removed husks (fiber) are then washed, squeezed, and dried using known processes in the industry to obtain corn husks.

[0071] Step 5: Concentrating the corn slurry C obtained in step 4: washing and desalting the corn slurry C using a vacuum drum filter, and concentrating the corn slurry to a water content of 70% by weight to obtain corn slurry D;

[0072] Step 6, slurry mixing, liquefaction, and saccharification: The pH of the corn slurry D obtained in step 5 is adjusted to 5.6-5.8. 0.015% by weight of a high-temperature liquefaction enzyme based on the dry weight of the corn starch is added at once, and the mixture is stirred and pre-liquefied at 60-65°C for half an hour. The adjusted corn slurry is spray-liquefied at 107°C, cooled to approximately 95°C, and liquefied for an additional 90 minutes. The DE value of the liquefied liquid is controlled to be between 14-18 and passes the iodine test. Filtering is performed to remove solids such as protein to obtain a clear liquefied liquid. The DE value of the liquefied liquid is measured to be 16.19, and the free starch content of the filter cake passes the iodine test. The pH of the liquefied liquid is adjusted to 4.0-4.2, the temperature is lowered to approximately 60°C, and 0.022% by weight of a saccharifying enzyme based on the dry weight of the corn starch is added. Saccharification is carried out for 50 hours to obtain a saccharified liquid. The DE value was detected to be 96.7, and the protein content was 67.7 wt %; the yield (dry basis) was detected as follows: sugar yield was 78.82 wt %, protein yield was 7.46 wt %, germ yield was 8.04 wt %, and fiber yield was 10.53 wt %.

[0073] Example 3

[0074] Step 1: Wash the corn (northeastern corn, with a water content of 15.15% by weight) with drinking water to remove dust from the surface of the corn, separate and remove the empty kernels and large and small corn debris from the corn, and drain the water.

[0075] Step 2: Weigh 5.0 kg of corn and 6.0 kg of water after the treatment in step 1, and continuously add them into a 10-liter high-pressure tubular soaking reactor. Heat the temperature to 60-63 ° C, pump the water pressure to 1 MPa, and react for 2 hours. Continuously unload the material into a normal pressure tank to obtain corn slurry A. The water content of the corn in corn slurry A is measured to be 38.67% by weight, and the soluble organic matter content in the clarified soaking water is 1.45% by weight, of which the organic matter contains 0.35% by weight of protein.

[0076] Step 3: Crushing and Germ Extraction: The corn slurry A from step 2 still contains a certain amount of corn kernels, which are crushed using a convex tooth mill and the germs are extracted using a cyclone to obtain corn slurry B. This process uses two-stage crushing and two-stage germ extraction. The extracted germ is washed, squeezed, and dried using known processes to obtain the germ.

[0077] Step 4: Fine Grinding to Remove Husks (Fiber): The corn slurry B obtained in step 3 is transferred to a pin mill, where the corn particles are further broken down. The husks are then screened out using a pressure sieve to obtain corn slurry C. A first-stage fine grinding and first-stage peeling process is employed. The removed husks (fiber) are then washed, squeezed, and dried using known processes in the industry to obtain corn husks.

[0078] Step 5: Concentrating the corn slurry C obtained in step 4: washing and desalting the corn slurry C using a vacuum drum filter, and concentrating the corn slurry to a water content of 70% by weight to obtain corn slurry D;

[0079] Step 6: Slurry mixing and liquefaction to prepare dextrin: The pH of the corn slurry D obtained in step 5 is adjusted to 5.6-5.8, 0.015% by weight of a high-temperature liquefaction enzyme based on the dry weight of the corn starch is added at once, and the mixture is stirred and pre-liquefied at 60-65°C for half an hour. The adjusted corn slurry is spray-liquefied at 107°C, cooled to approximately 95°C, and liquefied for an additional 90 minutes. The DE value of the liquefied liquid is controlled to be between 14-18 and pass the iodine test. Filtering is performed to remove solids such as protein to obtain a clear liquefied liquid. The DE value of the liquefied liquid is measured to be 16.73, and the free starch content of the filter cake passes the iodine test. The liquefied liquid is dried and refined to obtain dextrin. The dextrin was tested and the quality met the requirements of QB / T 5029-2017, with a protein content of 68.4 weight %; the yield (dry basis) was as follows: dextrin yield was 73.84 weight %, protein yield was 7.41 weight %, germ yield was 8.09 weight %, and fiber yield was 10.37 weight %.

[0080] Example 4

[0081] Step 1: Wash the corn (northeastern corn, with a water content of 14.05% by weight) with drinking water to remove dust from the surface of the corn, separate and remove the empty kernels and large and small corn debris from the corn, and drain the water.

[0082] Step 2: Weigh 5.0 kg of corn and 6.0 kg of water after the treatment in step 1, and continuously add them into a 10-liter high-pressure tubular immersion reactor. Heat the temperature to 60-63 ° C, pump the pressure to 1 MPa, and react for 2 hours. Continuously unload the material into a normal pressure tank to obtain corn slurry A. The water content of the corn in corn slurry A is determined to be 40.13% by weight, and the soluble organic matter content in the clarified immersion water is 1.24% by weight, of which the organic matter contains 0.32% by weight of protein.

[0083] Step 3: Crushing and Germ Extraction: The corn slurry A from step 2 still contains a certain amount of corn kernels, which are crushed using a convex tooth mill and the germs are extracted using a cyclone to obtain corn slurry B. This process uses two-stage crushing and two-stage germ extraction. The extracted germ is washed, squeezed, and dried using known processes to obtain the germ.

[0084] Step 4: Fine Grinding to Remove Husks (Fiber): The corn slurry B obtained in step 3 is transferred to a pin mill, where the corn particles are further broken down. The husks are then screened out using a pressure sieve to obtain corn slurry C. A first-stage fine grinding and first-stage peeling process is employed. The removed husks (fiber) are then washed, squeezed, and dried using known processes in the industry to obtain corn husks.

[0085] Step 5: Concentrating the corn slurry C obtained in step 4: washing and desalting the corn slurry C using a vacuum drum filter, and concentrating the corn slurry to a water content of 70% by weight to obtain corn slurry D;

[0086] Step 6, slurry adjustment, liquefaction, and saccharification: The pH of the corn slurry D obtained in step 5 is adjusted to 5.6-5.8, 0.015% by weight of a high-temperature liquefaction enzyme based on the dry weight of the corn starch is added at once, and the mixture is stirred and pre-liquefied at 60-65°C for half an hour. The adjusted corn slurry is spray-liquefied at 107°C, cooled to approximately 95°C, and liquefied for an additional 90 minutes. The DE value of the liquefied liquid is controlled to be between 14-18 and the iodine test is passed. Filtering is performed to remove solids such as protein to obtain a clear liquefied liquid. The pH of the liquefied liquid is adjusted to 4.0-4.2, the temperature is lowered to approximately 60°C, and 0.022% by weight of a saccharifying enzyme based on the dry weight of the corn starch is added. The mixture is saccharified for 48 hours to obtain a saccharified liquid. The DE value was detected to be 97.2, and the protein content was 67.9 wt %; the yield (dry basis) was detected as follows: sugar yield was 78.62 wt %, protein yield was 7.37 wt %, germ yield was 8.12 wt %, and fiber yield was 10.76 wt %.

[0087] Comparative Example 1

[0088] Step 1: Wash corn (water content 15.15% by weight) with drinking water to remove dust from the surface of the corn, remove the empty kernels and large and small corn debris from the corn, and drain the water;

[0089] Step 2: Weigh 2 kg of the purified corn from Step 1 and add it to a 10-liter autoclave reactor. Add 2.2 kg of water and 5 g of sulfurous acid, raise the temperature to 50°C, and maintain the reaction for 48 hours. Sampling and analysis yielded initial corn slurry A'. The corn's moisture content was determined to be 42.3% by weight; the clarified soaking water contained 7.99% by weight of soluble organic matter, and the protein content of the organic matter was 3.72% by weight.

[0090] Step 3: Remove the germ from the corn slurry A' in step 2 according to the method in step 3 of Example 2 to obtain corn slurry B';

[0091] Step 4: Remove the corn husk from the corn slurry B' in step 3 according to the method of step 4 of Example 2 to obtain corn slurry C';

[0092] Step 5: Separate the protein from corn slurry C' using three-stage centrifugal concentration to obtain corn slurry D'. Dehydrate the separated protein using a vacuum drum filter and dry it using a bundled tube dryer.

[0093] Step 6: Pump the corn slurry D' into a multi-stage cyclone washing machine to further wash away the protein, inorganic salts, etc. in the slurry to obtain corn slurry E';

[0094] Step 7: The corn slurry E' was slurried, liquefied, and saccharified according to the method of Step 6 of Example 2 to obtain a clear liquefied liquid with a DE value of 15.58 and a DE value of 97.5 for the sugar solution. The sugar yield was 73.87% and the protein yield was 5.23%.

[0095] As can be seen, in step 2 of Comparative Example 1, the organic matter concentration of the soaking water is too high to be used as process water in the system. It needs to be concentrated with steam to a water content of 50% by weight before being sprayed onto corn husks and sold as fiber feed or directly into the sewage treatment system. Furthermore, although Comparative Example 1 also produces qualified syrup, sulfurous acid is used during soaking, and wastewater with high organic matter concentration and "odor" are produced as by-products. Multi-stage centrifugation for protein separation and multi-stage washing for protein removal are required, increasing equipment investment and energy consumption. Furthermore, the sugar and protein yields are not as high as those of the new process.

Claims

1. A method for deep processing corn using a pressure soaking method, particularly for preparing dextrin, syrup or sugar, comprising the following steps: (1) adding corn, water, and optional chemical additives continuously or in batches into a pressurized soaking reactor; reacting in the reactor at a reaction temperature of 20-70° C. and a gauge pressure of 0.1 MPa or more for more than 0.5 hour, and discharging the materials continuously or intermittently to obtain a water-containing corn slurry A; (2) removing the germ from the corn slurry A in step (1) to obtain corn slurry B and germ; (3) defibering the corn slurry B in step (2) to obtain corn slurry C and corn husks; (4) The corn slurry C in step (3) is directly slurried and liquefied without undergoing a starch refining process, and the solids in the liquefied liquid are separated and further processed to obtain protein; (5) The liquefied liquid after solids are separated in step (4) is dried to obtain dextrin; or the liquefied liquid is saccharified to obtain syrup, and the syrup is optionally further crystallized to obtain sugar.

2. The method of claim 1, wherein Introducing a suitable gas or water that does not affect the reaction, such as air, nitrogen, oxygen and / or water, into the reactor to increase the pressure of the reactor, and / or The pressurized immersion reactor is one or more pressure vessels such as a pressure autoclave, a pressure tank, a tubular reactor, a digester (pot), a pressure screw conveyor, a tower, a steam ball, an autoclave, a decomposition pot, a vulcanizing tank, etc., which can be used alone or in series or in parallel.

3. The method of claim 1 or 2, wherein In the reactor, the gauge pressure of the reaction is 0.1-10 MPa, more preferably 0.5-8 MPa, still more preferably 0.5-6 MPa, and / or In the reactor, the reaction time is 0.5-10 hours, more preferably 0.5-8 hours, still more preferably 0.5-6 hours, and / or In the reactor, the reaction temperature is 40-70°C, more preferably 45-65°C.

4. The method according to any one of claims 1 to 3, wherein The corn is first washed with water to remove impurities on the surface of the corn, and the empty kernels and large and small corn debris are optionally separated and removed, and the water is drained, and / or In addition to corn and water, a chemical additive is added to the reactor. The chemical additive may be an acid, a base (including Lewis acid or base) or an enzyme. Preferably, the amount of the chemical additive is 0-10 wt %, more preferably 0-1.5 wt %, and even more preferably 0-1 wt %, based on the dry weight of the corn.

5. The method according to any one of claims 1 to 4, wherein The moisture content of the corn in the obtained corn slurry A is greater than or equal to 35 weight %, more preferably greater than or equal to 38 weight %, and even more preferably greater than or equal to 40 weight %, and / or The water is selected from drinking water, deionized water or recycled process water, etc. Preferably, the amount of water added is 20-300 weight % based on the dry weight of the corn, more preferably 50-250 weight %, even more preferably 70-200 weight %, and further more preferably 90-150 weight %.

6. The method according to any one of claims 1 to 5, wherein In step (2), degermination is performed by further crushing the corn in the corn slurry A obtained in step (1) and then separating the germ using a cyclone, and / or In step (3), the fiber removal is carried out as follows: the corn steep liquor B material after the germ removal in step (2) is further crushed, for example, by grinding and then screening with koji to remove the fiber, and / or In step (4), the corn slurry C after removing the germ and fiber is concentrated by a filter or centrifuge (optionally washed and desalted) to a water content of 40-70% by weight, preferably 50-70% by weight; the slurry adjustment temperature is preferably 60-65°C, and the pH is preferably 5.5-6; the liquefaction is carried out by spraying, or gentle liquefaction at 76-100°C, wherein a liquefaction enzyme is added in an amount of 0.1-0.5 kg / ton of dry corn starch; the DE value of the liquefied liquid is controlled to be 14-18; the solids, for example, contain protein, and / or The liquefied liquid after the solids are removed in step (5) is dried to obtain a dextrin product, and / or The pH value of the liquefied liquid after the solids are separated in step (5) is adjusted to 4.0-4.4, preferably 4.0-4.2 during saccharification; the sugar is preferably glucose; the DE value of the saccharified liquid after saccharification of the liquefied liquid is 95-98.

7. The method according to any one of claims 1 to 6, wherein In step (4), the starch refining process refers to centrifugation and starch washing, and / or In step (5), the further treatment refers to filtration, decolorization, ion exchange, and concentration.

8. The method according to any one of claims 1 to 7, comprising the steps of: Step 1: Wash the corn with water to remove dust from the surface of the corn, separate the empty kernels and large and small corn debris from the corn, and drain the water; Step 2: Weigh the corn treated in step (1), add it to a pressurized soaking reactor, add 20-300 wt% of water based on the dry weight of the corn, react in the reactor at 20-70° C. and 0.1-10 MPa for 0.5-10 hours, and discharge the mixture continuously or in batches into a normal pressure tank to obtain a water-containing corn slurry A; Step 3, crushing and extracting germ: The corn slurry A obtained in step 2 still contains a certain amount of corn kernels, which are crushed by a convex tooth mill and the germs are extracted by a cyclone to obtain corn slurry B. The crushing can be performed in a primary stage to extract the germs, or in a secondary stage to extract the germs. The extracted germs are washed, squeezed, and dried to obtain the germs. Step 4, fine grinding to remove corn husks (fiber): The corn slurry B from which the germ has been removed in step 3 is transported to fine grinding, where the corn particles are further crushed and the corn husks are screened out. A first-stage fine grinding and first-stage peeling or a second-stage fine grinding and second-stage peeling can be performed to obtain corn slurry C. The removed corn husks (fiber) are washed, squeezed, and dried to obtain corn husks. Step 5: Concentrating the corn slurry C in step 4: Concentrating the corn slurry to a water content of 40-70% by weight using a centrifuge or filter. Preferably, a vacuum drum filter is used for concentration while washing and desalting to obtain corn slurry D. Step 6, dextrin, syrup, sugar and protein preparation: the pH value of the corn slurry D in step 5 is adjusted to 5.6-5.8, 0.01-0.03 weight % of high temperature liquefaction enzyme based on the dry weight of corn starch is added, and pre-liquefaction is stirred at 60-65 ° C for half an hour; the adjusted corn slurry is instantly heated to 76-100 ° C, stirred and liquefied for 10-30 minutes, or sprayed at 102-108 ° C, cooled to 90-95 ° C, and then liquefied for 90-120 minutes; the DE value of the liquefied liquid is controlled to be 14-18, the iodine test is qualified, filtered, and solids (filter cake) are filtered out to obtain a clarified liquefied liquid, which can be dried to obtain dextrin, or the liquefied liquid can be saccharified to obtain syrup, or further crystallized to obtain sugar; the filter cake is washed and dried to obtain protein.

9. The protein, germ, corn bran, dextrin, syrup and / or sugar obtained by the method according to any one of claims 1 to 8.