Preparation method and application of acid-process starch syrup

Abstract

The invention belongs to the technical field of starch sugar processing, and particularly relates to a preparation method and application of acid-process starch syrup. The preparation method of the acid-process starch syrup comprises the following steps: enabling pure water to pass through a strong acid cation exchange resin column to obtain acidic pure water; then mixing with starch, and performing size mixing to obtain a material A; carrying out heating, pressure maintaining, heat preservation and cooling on the material A to obtain a material B, adjusting the pH of the material B to be acidic, filtering, and taking filtrate to obtain a material C; deacidifying through a weak base anion exchange resin column to obtain a material D; then adjusting the pH to be acidic to obtain a material E; the material E sequentially passes through a sodium type strong acid cation exchange resin column and a chlorine type strong base ion exchange resin column to obtain a material F; and refining through an activated carbon column to obtain a material G, and concentrating to obtain the product. According to the method, the ash content of the acid-process starch hydrolysis saccharification liquid can be reduced, and the excessive sugar multiple of the ion exchange resin column is improved, so that the consumption of an ion exchange resin regenerant is reduced, and the acid-process starch syrup which is relatively low in ash content and not easy to discolor during storage is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of starch sugar processing, and particularly relates to a preparation method and application of acid-process starch syrup. Background Art

[0002] Before the introduction of enzymatic sugar production technology into China, the mainstream starch production process was acid hydrolysis and saccharification. Inorganic acid was added to starch slurry as a catalyst, causing the starch to hydrolyze under the action of acid and heat to produce glucose solution, which was then further refined to produce acid-based starch syrup. With the advancement and development of enzymatic starch production technology in China, the advantages of high quality and low manufacturing costs of enzymatic starch sugar have become increasingly significant, and the application of acid-based starch sugar in the food industry has gradually been replaced by enzymatic starch sugar. Although enzymatic starch sugar can achieve a similar sugar composition to acid-based starch sugar, foods such as aerated candies produced using acid-based starch sugar have superior taste and quality characteristics. Therefore, acid-based starch syrup remains irreplaceable in food applications requiring high taste quality.

[0003] The traditional acid-based sugar production process involves mixing starch and tap water to prepare a slurry, adding an inorganic acid to adjust the pH, heating, maintaining the temperature, and saccharifying under pressure. After cooling, soda ash is added for neutralization. Powdered activated carbon is added for decolorization and filtration. The filtrate is then purified by passing it through a sodium-type strong-acid cation exchange resin column and a chloride-type strong-base anion exchange resin column. Powdered activated carbon is then added for further purification and filtration, and the filtrate is concentrated to produce the finished acid-based starch sugar. The traditional acid-based syrup production process produces a dark-colored, high-ash-content starch sugar hydrolyzate. The syrup is refined using sodium-type strong-acid cation exchange resin columns and chloride-type strong-base anion exchange resin columns. Activated carbon is added before and after ion exchange for decolorization or purification. The starch syrup produced by this process is less prone to discoloration during storage. However, the ion exchange process involves the exchange of sodium and chloride ions on the ion exchange resin with divalent or higher ions in the sugar solution, which then enter the sugar solution. Consequently, the finished syrup contains a high amount of ash, which affects the taste of the syrup.

[0004] On the one hand, the enzymatic starch sugar-making process has replaced the acid sugar-making process to become the mainstream starch sugar-making process; on the other hand, the acid starch syrup produced by the traditional process contains a higher ash content, which affects the sweetness perception and flavor of the food for the intended use of the syrup. Therefore, the softening and refining process of the sodium-type strong acid cation exchange resin column and the chloride-type strong base anion exchange resin column suitable for acid starch sugar-making has also been replaced by the desalting and refining process of the strong acid cation exchange resin column and the weak base anion exchange resin column suitable for enzymatic starch sugar-making. In the production of acid-process starch sugar, inorganic acid needs to be added to adjust the pH of starch during starch slurry preparation, and then the starch is hydrolyzed and saccharified at high temperature, and then the pH is adjusted with soda ash. Therefore, the ash content of the acid-process starch hydrolysis and saccharification liquid is much higher than that of the enzymatic starch hydrolysis and saccharification liquid; at high temperature, high ash content can promote the production of colored substances in the starch hydrolysis and saccharification process; because the ash content and chroma of the acid-process starch hydrolysis and saccharification liquid are higher than those of the enzymatic starch hydrolysis and saccharification liquid, when strong acid cation exchange resin columns and weak base anion exchange resin columns are used for the refining of acid-process starch hydrolysis and saccharification liquid, compared with the softening and refining process of the traditional sodium-type strong acid cation exchange resin column and chloride-type strong base anion exchange resin column, the unit cycle production capacity of the ion exchange resin column decreases, the production cost increases, and the color of the acid-process starch sugar product is prone to increase during storage.

[0005] Therefore, it is of great significance to provide a method for preparing high-quality acid-process starch syrup that can reduce the ash content of acid-process starch hydrolysis saccharification liquid, increase the sugar pass ratio of ion exchange resin column, thereby reducing the consumption of ion exchange resin regeneration agent, and obtain low ash content and is not easy to change color during product storage. Summary of the Invention

[0006] The present invention aims to solve one or more technical problems existing in the above-mentioned prior art and to provide at least a beneficial alternative. Specifically, the present invention provides a method for preparing acid-process starch syrup, which can reduce the ash content of acid-process starch hydrolyzed saccharification liquid, increase the sugar pass ratio of ion exchange resin columns, thereby reducing the consumption of ion exchange resin regeneration agent, and obtain high-quality acid-process starch syrup with low ash content and low discoloration during storage.

[0007] The inventive concept of the present invention is as follows: the preparation method of the acid-process starch syrup of the present invention comprises the following steps: passing pure water through a strong acid cation exchange resin column, collecting effluent to obtain acidic pure water; mixing the acidic pure water and starch, adjusting the slurry and pH to obtain material A; heating material A, maintaining pressure, maintaining temperature, and cooling to obtain material B; adjusting the pH of material B to acidic, filtering with a ceramic membrane, and collecting the filtrate to obtain material C; deacidifying material C through a weak base anion exchange resin column, collecting the effluent to obtain material D; adjusting the pH of material D to acidic to obtain material E; passing material E sequentially through a sodium-type strong acid cation exchange resin column and a chloride-type strong base ion exchange resin column, collecting the effluent to obtain material F; then refining through an activated carbon column, collecting the effluent to obtain material G; and concentrating material G to obtain acid-process starch syrup.

[0008] The invention adopts pure water (RO pure water) treated by reverse osmosis technology to prepare acidic pure water through a strong acid cation exchange resin column for slurry adjustment, thereby reducing the amount of inorganic acid added for starch slurry adjustment and pH adjustment, thereby reducing the ash content of the starch slurry and reducing the generation of colored substances during starch hydrolysis and saccharification at high temperature; adopts a weak base anion exchange resin column to perform adsorption deacidification on the acid-processed starch hydrolysis and saccharification liquid, instead of adding soda ash to adjust the pH of the acid-processed starch hydrolysis and saccharification liquid, thereby further reducing the ash content of the sugar liquid; adopts a sodium-type strong acid cation exchange resin column and a chloride-type strong base anion exchange resin column to purify the acid-processed starch hydrolysis and saccharification liquid, wherein divalent and higher ions in the sugar liquid exchange with sodium ions on the cation exchange resin and chloride ions on the anion exchange resin, and the sodium ions and chloride ions obtained by the ion exchange enter the sugar liquid; adopts an activated carbon column refining process, thereby improving the syrup quality and realizing fully automatic production.

[0009] Compared with the traditional process, the preparation method of the present invention adopts acidic pure water for slurry adjustment, which can reduce the amount of inorganic acid added for adjusting the pH of starch slurry, thereby reducing the amount of alkali added for adjusting the pH of acid-process starch hydrolysis saccharification liquid in the subsequent process, thereby reducing the ash content of the starch hydrolysis saccharification liquid; a weak base anion exchange resin column is used to adsorb and deacidify the starch hydrolysis saccharification liquid, instead of adding alkali to adjust the pH of the starch hydrolysis saccharification liquid, thereby reducing the ash content of the starch hydrolysis saccharification liquid; through the above two technical conditions, the ash content of the starch hydrolysis saccharification liquid is controlled at a low level, and then a softening and refining process of a sodium-type strong acid cation exchange resin column and a chloride-type strong base anion exchange resin column is adopted to replace the desalting and refining process of a hydrogen-type strong acid cation exchange resin column and a weak base anion exchange resin column, thereby greatly improving the sugar passing multiple of the ion exchange resin column, thereby reducing the consumption of the ion exchange resin regeneration agent, and obtaining high-quality acid-process starch syrup with low ash content and not easy to change color during product storage.

[0010] Therefore, a first aspect of the present invention provides a method for preparing an acid starch syrup.

[0011] Specifically, the preparation method of the acid starch syrup comprises the following steps:

[0012] (1) Pure water is passed through a strong acid cation exchange resin column to obtain acidic pure water; the acidic pure water is mixed with starch and slurried to obtain material A;

[0013] (2) The material A obtained in step (1) is heated, pressure-maintained, heat-maintained, and cooled to obtain material B; the pH of the material B is adjusted to acidic, filtered, and the filtrate is collected to obtain material C;

[0014] (3) The material C obtained in step (2) is deacidified by a weak base anion exchange resin column to obtain material D; the pH of the material D is adjusted to acidic to obtain material E;

[0015] (4) The material E obtained in step (3) is sequentially refined by a sodium-type strong acid cation exchange resin column and a chloride-type strong base ion exchange resin column to obtain material F; then refined by an activated carbon column to obtain material G, and the material G is concentrated to obtain acid-process starch syrup.

[0016] Preferably, in step (1), the pure water is pure water treated by reverse osmosis technology (RO pure water), the conductivity of the pure water is 5-30 μS / cm, and the pH of the pure water is 5.0-7.0.

[0017] Further preferably, the conductivity of the pure water is 8-25 μS / cm, and the pH of the pure water is 5.0-6.5.

[0018] Preferably, in step (1), the strong acid cation exchange resin column is a hydrogen-type strong acid cation exchange resin column.

[0019] Specifically, the acidic pure water is the decationized acidic pure water obtained by treating the pure water treated by reverse osmosis technology with a hydrogen-type strong acid cation exchange resin column.

[0020] Preferably, in step (1), the pH of the acidic pure water is 3.0-4.5; further preferably, the pH of the acidic pure water is 3.0-4.0.

[0021] Preferably, in step (1), the strong acid cation exchange resin column is regenerated using a hydrochloric acid solution.

[0022] Preferably, the mass fraction of the hydrochloric acid solution is 4-6%; further preferably, the mass fraction of the hydrochloric acid solution is 4.5-5.5%; even further preferably, the mass fraction of the hydrochloric acid solution is 5%.

[0023] Preferably, in step (1), the slurry adjustment is to adjust the concentration of the slurry after the starch and acidic pure water are mixed to 16-20 degrees Baume (°Bé); further preferably, the slurry adjustment is to adjust the concentration of the slurry after the starch and acidic pure water are mixed to 16.5-19.5°Bé.

[0024] Preferably, in step (1), the slurry adjustment further includes a process of adjusting the pH to acidic.

[0025] Preferably, hydrochloric acid is used to adjust the pH to acidic; further preferably, the hydrochloric acid is food grade hydrochloric acid.

[0026] Preferably, the pH is 1.4-2.1, more preferably, the pH is 1.5-1.9.

[0027] Preferably, in step (2), the heating process includes placing the material A into a hydroheater and mixing it with steam to heat it.

[0028] Preferably, the insulation temperature is 120-140°C; further preferably, the insulation temperature is 125-135°C.

[0029] Preferably, the insulation time is 14-45 minutes; further preferably, the insulation time is 15-40 minutes.

[0030] Preferably, the temperature corresponding to the cooling is 80-100°C; further preferably, the temperature corresponding to the cooling is 90-100°C.

[0031] Specifically, the pressure is maintained during the heat preservation process, and the specific heat preservation and pressure holding time are adjusted according to the glucose equivalent (DE value) of the saccharification liquid. When the DE value of the saccharification liquid is 38-48 (or meets the customer's quality standards), the saccharification liquid is cooled to 80-100°C and discharged to obtain material B.

[0032] Preferably, in step (2), the pH is adjusted to 2.5-3.5; further preferably, the pH is adjusted to 2.7-3.3.

[0033] Preferably, in step (2), a soda ash solution is used to adjust the pH of the material B.

[0034] Preferably, the mass fraction of the soda ash solution is 4-6%; further preferably, the mass fraction of the soda ash solution is 4.5-5.5%; even further preferably, the mass fraction of the soda ash solution is 5%.

[0035] Preferably, in step (2), the filtration further includes a cooling process, and the temperature corresponding to the cooling is 65-80°C; further preferably, the temperature corresponding to the cooling is 65-75°C.

[0036] Preferably, in step (2), a ceramic membrane is used for the filtration.

[0037] Specifically, the filtrate is the membrane permeate of the ceramic membrane, and the filtrate is collected to obtain material C.

[0038] Preferably, in step (3), the temperature of the syrup in the weak base anion exchange resin column is 40-50°C; further preferably, the temperature of the syrup in the weak base anion exchange resin column is 40-45°C.

[0039] Preferably, in step (3), the discharge pH of the weak base anion exchange resin column is 4.0-6.0; further preferably, the discharge pH of the weak base anion exchange resin column is 4.5-6.0.

[0040] Preferably, in step (3), the weak base anion exchange resin column is regenerated with a sodium hydroxide solution, and the output is collected to obtain the material D;

[0041] Preferably, the mass fraction of the sodium hydroxide solution is 3-5%; further preferably, the mass fraction of the sodium hydroxide solution is 3.5-4.5%; even further preferably, the mass fraction of the sodium hydroxide solution is 4%.

[0042] Preferably, in step (3), the pH of the material D is adjusted to 4.0-6.0; further preferably, in step (3), the pH of the material D is adjusted to 4.5-5.5.

[0043] Preferably, material C or a soda ash solution is used to adjust the pH of the material D to acidic.

[0044] Specifically, the material C is acidic.

[0045] Preferably, the mass fraction of the soda ash solution is 4-6%; further preferably, the mass fraction of the soda ash solution is 4.5-5.5%; even further preferably, the mass fraction of the soda ash solution is 5%.

[0046] Preferably, in step (4), the temperature of the syrup in the sodium-type strong acid cation exchange resin column and the chloride-type strong base ion exchange resin column is 40-50°C; further preferably, the temperature of the syrup in the sodium-type strong acid cation exchange resin column and the chloride-type strong base ion exchange resin column is 40-45°C.

[0047] Preferably, in step (4), the sodium-type strong acid cation exchange resin column and the chloride-type strong base ion exchange resin column are regenerated using a sodium chloride solution, and the output is collected to obtain material F.

[0048] Preferably, the mass fraction of the sodium chloride solution is 9-11%; further preferably, the mass fraction of the sodium chloride solution is 9.5-10.5%; even further preferably, the mass fraction of the sodium chloride solution is 10%.

[0049] Specifically, material E is refined by sodium-type strong acid cation exchange resin and chloride-type strong base anion exchange resin, using a cation-anion, cation-anion secondary ion exchange process.

[0050] When the color difference between the inlet and outlet syrups of the primary ion exchange column is ≤0.5RBU (using the color detection method of "Starch Sugar Quality Requirements Part 4: Fructose Syrup GBT 20882.4-2021"), stop using it, convert the secondary ion exchange column to the primary ion exchange column, and convert the regenerated ion exchange column to the secondary ion exchange column. The cation and anion exchange resins are regenerated with sodium chloride solution.

[0051] Preferably, in step (4), the activated carbon refining is granular activated carbon column refining, and the syrup temperature in the granular activated carbon column is 45-65°C; further preferably, the syrup temperature in the granular activated carbon column is 50-60°C.

[0052] Preferably, the granular activated carbon in the granular activated carbon column is regenerated using a sodium hydroxide solution.

[0053] Preferably, the mass fraction of the sodium hydroxide solution is 3-5%; further preferably, the mass fraction of the sodium hydroxide solution is 3.5-4.5%; even further preferably, the mass fraction of the sodium hydroxide solution is 4%.

[0054] Specifically, when the color difference between the inlet and outlet syrups of the granular activated carbon column is ≤0.5RBU (tested using the colorimetric detection method of "Starch Sugar Quality Requirements Part 4: Fructose Syrup GBT 20882.4-2021"), stop using and regenerate.

[0055] The second aspect of the present invention provides an application of the preparation method described in the first aspect of the present invention in the field of preparing acid starch syrup.

[0056] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: the present invention uses RO pure water to pass through a strong acid cation exchange resin column to prepare acidic pure water for slurry adjustment, thereby reducing the amount of inorganic acid added for slurry pH adjustment, thereby reducing the amount of alkali added for pH adjustment of the acid-processed starch hydrolysis saccharification liquid in the subsequent process, thereby reducing the ash content of the starch hydrolysis saccharification liquid; a weak base anion exchange resin column is used to perform adsorption deacidification on the starch hydrolysis saccharification liquid, instead of adding alkali to adjust the pH of the starch hydrolysis saccharification liquid, thereby reducing the ash content of the starch hydrolysis saccharification liquid; through the above two technical conditions, the ash content of the starch hydrolysis saccharification liquid is controlled at a low level, and then a softening and refining process using a sodium-type strong acid cation exchange resin column and a chloride-type strong base anion exchange resin column is used to replace the desalting and refining process using a hydrogen-type strong acid cation exchange resin column and a weak base anion exchange resin column, thereby greatly improving the sugar pass ratio of the ion exchange resin, thereby reducing the consumption of the ion exchange resin regeneration agent, and obtaining a high-quality acid-processed starch syrup with a low ash content and not easy to discolor during product storage.

[0057] Specifically, compared with the prior art, this application has the following advantages:

[0058] (1) The present invention uses RO pure water to pass through a strong acid cation exchange resin column to prepare decationized acidic pure water for slurry mixing. Compared with the traditional process of tap water slurry mixing, the amount of inorganic acid added to adjust the pH of the slurry is greatly reduced, thereby reducing the ash content of the slurry.

[0059] (2) The ash content of the slurry after slurry adjustment in the present invention is lower than that of the traditional process, and the chroma of the saccharified liquid obtained in the starch hydrolysis and saccharification process at high temperature is lighter than that of the traditional process, which reduces the refining cost of the subsequent process.

[0060] (3) The present invention adopts ceramic membrane filtration to replace traditional plate and frame filtration, realizes soilless filtration in the production of acid starch sugar, and enables continuous automated production.

[0061] (4) A weak base anion exchange resin column is used to adsorb and deacidify the acid-processed starch hydrolyzed saccharification liquid, instead of adding soda ash to adjust the pH of the acid-processed starch hydrolyzed saccharification liquid, thereby further reducing the ash content of the sugar liquid.

[0062] (5) The present invention adopts acidic pure water for slurry adjustment and weak base anion exchange resin column instead of adding soda ash to adjust pH. The ash content of the acid-process starch hydrolysis saccharification liquid obtained is lower than that of the traditional process. The sodium-type strong acid cation exchange resin column and the chloride-type strong base anion exchange resin column are further used to refine the sugar solution. The divalent and higher ions in the sugar solution undergo ion exchange with the sodium ions on the cation exchange resin and the chloride ions on the anion exchange resin. The sodium ions and chloride ions obtained by ion exchange enter the sugar solution, rather than a complete deionization desalination process. Therefore, the ion exchange resin column has a higher sugar pass ratio, and the ash content of the sugar solution after ion exchange is lower than that of the traditional process.

[0063] (6) The chroma of the acid-processed starch hydrolyzed saccharification liquid of the present invention is lower than that of the traditional process. Both the weak base anion exchange resin and the strong base anion exchange resin have decolorization capabilities. After ion exchange, the sugar liquid is further refined using a granular activated carbon column to meet the syrup quality requirements. Compared with the powdered activated carbon decolorization and refining process of the traditional process, continuous automated production and a more friendly production environment can be achieved.

[0064] (7) Compared with the traditional process of softening and refining with strong acid and strong base ion exchange resins, the acid-processed starch sugar product obtained by the preparation method and application of the present invention obtains acid-processed starch syrup with lower ash content, and solves the problem of the influence of high ash content of syrup on the intended use of syrup, sweetness perception and flavor of food; compared with the existing process of refining with strong acid and weak base ion exchange resins, the acid-processed starch syrup with lower ash content is obtained, and the product is not easy to change color during storage, and the sugar conversion ratio of ion exchange resin is greatly improved, thereby reducing the consumption of ion exchange resin regeneration agent. DETAILED DESCRIPTION

[0065] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0066] Unless otherwise specified, the raw materials, reagents, or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0067] The ion exchange resin models used in the Examples of the present invention and the Comparative Examples are as follows:

[0068] Weak base anion exchange resin, specifically Dow FPA66UPS; strong acid cation exchange resin, specifically Dow 88NPS; strong base anion exchange resin, specifically Dow FPA90RFCL; granular activated carbon, specifically Yuanli YL-HA-A.

[0069] The chemicals used in the examples and comparative examples of the present invention, such as liquid hydrochloric acid, liquid sodium hydroxide, sodium chloride, soda ash, etc., are all food additives.

[0070] Example 1

[0071] A method for preparing acid starch syrup comprises the following steps:

[0072] (1) Preparation of slurry water: RO pure water with a conductivity of 10 μS / cm and a pH of 5.9 is passed through a strong acid cation exchange resin column to obtain acidic pure water with a conductivity of 12 μS / cm and a pH of 3.9;

[0073] (2) Slurry adjustment and pH adjustment: acidic pure water and corn starch are slurried to 18° Bé, and the pH is adjusted to 1.7 with 5 wt% food-grade hydrochloric acid to obtain material A;

[0074] (3) Saccharification: Material A enters the hydrothermal reactor and is mixed with steam to raise the temperature to 130°C. It then enters the maintenance column to maintain pressure and temperature for 25 minutes. The discharge temperature is then cooled to 95°C to obtain material B with a DE of 42.3.

[0075] (4) Filtration: Material B was added with 5 wt% sodium carbonate solution to adjust the pH to 3.0, then cooled to 70°C and filtered through a ceramic membrane. The supernatant was collected to obtain material C.

[0076] (5) Deacidification: Material C is deacidified by passing it through a weak base anion exchange resin column. The temperature of the syrup in the ion exchange column is 45°C, and the pH of the ion exchange resin output is ≥4.5. The weak base anion exchange resin column is regenerated with a 4 wt% sodium hydroxide solution, and the output is collected to obtain material D.

[0077] (6) pH adjustment: 5 wt% sodium carbonate solution was added to material D to adjust the pH to 5.1 to obtain material E;

[0078] (7) Ion exchange: Material E is refined by a sodium-type strong acid cation exchange resin column and a chloride-type strong base anion exchange resin. The syrup temperature in the ion exchange column is 45°C. The ion exchange resin is regenerated with a 10 wt% sodium chloride solution. The discharged material is collected to obtain material F.

[0079] (8) Refining: Material E is then purified by a granular activated carbon column at a temperature of 45°C to obtain material G;

[0080] (9) Material G is concentrated to obtain an acid starch syrup product.

[0081] Example 2

[0082] A method for preparing acid starch syrup comprises the following steps:

[0083] (1) Preparation of slurry water: RO pure water with a conductivity of 20 μS / cm and a pH of 5.9 was passed through a strong acid cation exchange resin column to obtain acidic pure water with a conductivity of 57 μS / cm and a pH of 3.5;

[0084] (2) Slurry adjustment and pH adjustment: acidic pure water and corn starch are slurried to 17° Bé, and the pH is adjusted to 1.8 with 5 wt% food-grade hydrochloric acid to obtain material A;

[0085] (3) Saccharification: Material A enters a hydrothermal reactor and is mixed with steam to raise the temperature to 125°C. It then enters a holding column to maintain pressure and temperature for 30 minutes. The discharge temperature is then cooled to 95°C to obtain material B with a DE of 43.1.

[0086] (4) Filtration: Material B was added with 5 wt% sodium carbonate solution to adjust the pH to 3.2, then cooled to 70°C and filtered through a ceramic membrane. The supernatant was collected to obtain material C.

[0087] (5) Deacidification: Material C is deacidified by passing it through a weak base anion exchange resin column. The temperature of the syrup in the ion exchange column is 45°C, and the pH of the ion exchange resin output is ≥4.5. The weak base anion exchange resin column is regenerated with a 4 wt% sodium hydroxide solution, and the output is collected to obtain material D.

[0088] (6) pH adjustment: 5 wt% sodium carbonate solution was added to material D to adjust the pH to 5.0 to obtain material E;

[0089] (7) Ion exchange: Material E is refined by a sodium-type strong acid cation exchange resin column and a chloride-type strong base anion exchange resin. The syrup temperature in the ion exchange column is 45°C. The ion exchange resin is regenerated with a 10% sodium chloride solution. The discharged material is collected to obtain material F.

[0090] (8) Refining: Material E is then purified by a granular activated carbon column at a temperature of 45°C to obtain material G;

[0091] (9) Material G is concentrated to obtain an acid starch syrup product.

[0092] Example 3

[0093] A method for preparing acid starch syrup comprises the following steps:

[0094] (1) Preparation of slurry water: RO pure water with a conductivity of 25 μS / cm and a pH of 5.9 was passed through a strong acid cation exchange resin column to obtain acidic pure water with a conductivity of 65 μS / cm and a pH of 3.4;

[0095] (2) Slurry adjustment and pH adjustment: acidic pure water and corn starch are slurried to 19° Bé, and the pH is adjusted to 1.6 with 5 wt% food-grade hydrochloric acid to obtain material A;

[0096] (3) Saccharification: Material A enters the hydrothermal reactor and is mixed with steam to raise the temperature to 135°C. It then enters the maintenance column to maintain pressure and temperature for 20 minutes. The discharge temperature is then cooled to 95°C to obtain material B with a DE of 44.2.

[0097] (4) Filtration: Add 5 wt% sodium carbonate solution to material B to adjust the pH to 2.7, then cool it to 70°C and filter it through a ceramic membrane. Collect the membrane filtration clear liquid to obtain material C;

[0098] (5) Deacidification: Material C is deacidified by passing it through a weak base anion exchange resin column. The temperature of the syrup in the ion exchange column is 45°C, and the pH of the ion exchange resin output is ≥4.5. The weak base anion exchange resin column is regenerated with a 4 wt% sodium hydroxide solution, and the output is collected to obtain material D.

[0099] (6) pH adjustment: 5 wt% sodium carbonate solution was added to material D to adjust the pH to 5.2 to obtain material E;

[0100] (7) Ion exchange: Material E is refined by sodium-type strong acid cation exchange resin and chloride-type strong base anion exchange resin. The syrup temperature in the ion exchange column is 45°C. The ion exchange resin is regenerated with 10% sodium chloride solution. The discharged material is collected to obtain material F.

[0101] (8) Refining: Material E is then purified by a granular activated carbon column at a temperature of 45°C to obtain material G;

[0102] (9) Material G is concentrated to obtain an acid starch syrup product.

[0103] Comparative Example 1

[0104] A method for preparing acid starch syrup comprises the following steps:

[0105] (1) Slurry preparation: tap water and corn starch were slurried to 18° Bé, and the pH was adjusted to 1.7 with 5 wt% food-grade hydrochloric acid to obtain material A;

[0106] (2) Saccharification: Material A enters the hydrothermal reactor and is mixed with steam to raise the temperature to 130°C. It then enters the maintenance column to maintain pressure and temperature for 25 minutes. The discharge temperature is then cooled to 95°C to obtain material B with a DE of 42.8.

[0107] (3) Filtration: Add 5 wt% sodium carbonate solution to material B to adjust the pH to 4.8, then cool to 70°C, add powdered activated carbon and filter aid recovered from secondary filtration, and filter through plate and frame filtration. Collect the filtered supernatant to obtain material C.

[0108] (4) Secondary decolorization and filtration: Add powdered activated carbon and filter aid to material C, filter it into a plate and frame filter, and collect the filtered clear liquid to obtain material D;

[0109] (5) Ion exchange: Material D was refined by sodium-type strong acid cation exchange resin and chloride-type strong base anion exchange resin. The syrup temperature in the ion exchange column was 45°C. A secondary ion exchange process was used. The ion exchange resin was regenerated with 10 wt% sodium chloride solution. The discharged material was collected to obtain material E.

[0110] (6) pH adjustment and filtration: Add powdered activated carbon and filter aid to material E and keep it warm at 65°C. Add 5 wt% sodium carbonate solution to adjust the pH to 5.0, filter it into a plate and frame filter, and collect the filtered supernatant to obtain material F;

[0111] (7) Material F is concentrated to obtain an acid starch syrup product.

[0112] Comparative Example 2

[0113] A method for preparing acid starch syrup comprises the following steps:

[0114] (1) Slurry preparation: tap water and corn starch were slurried to 17° Bé, and the pH was adjusted to 1.8 with 5 wt% food-grade hydrochloric acid to obtain material A;

[0115] (2) Saccharification: Material A enters a hydrothermal reactor and is mixed with steam to raise the temperature to 125°C. It then enters a holding column to maintain pressure and temperature for 30 minutes. The discharge temperature is then cooled to 95°C to obtain material B with a DE of 43.5.

[0116] (3) Filtration: Add 5 wt% soda ash solution to material B to adjust the pH to 4.8, then cool to 70°C, add powdered activated carbon and filter aid recovered from secondary filtration, and filter through plate and frame filtration. Collect the filtered supernatant to obtain material C;

[0117] (4) Secondary decolorization and filtration: Add powdered activated carbon and filter aid to material C, filter it into a plate and frame filter, and collect the filtered clear liquid to obtain material D;

[0118] (5) Ion exchange: Material D was refined by sodium-type strong acid cation exchange resin and chloride-type strong base anion exchange resin. The syrup temperature in the ion exchange column was 45°C. A secondary ion exchange process was used. The ion exchange resin was regenerated with 10 wt% sodium chloride solution. The discharged material was collected to obtain material E.

[0119] (6) pH adjustment and filtration: Add powdered activated carbon and filter aid to material E and keep it warm at 65°C. Add 5 wt% sodium carbonate solution to adjust the pH to 5.1. Filter the material through plate and frame filtration and collect the filtered supernatant to obtain material F.

[0120] (7) Material F is concentrated to obtain an acid starch syrup product.

[0121] Comparative Example 3

[0122] A method for preparing acid starch syrup comprises the following steps:

[0123] (1) Slurry preparation: RO pure water and corn starch were slurried to 18° Bé, and the pH was adjusted to 1.7 with 5 wt% food-grade hydrochloric acid to obtain material A;

[0124] (2) Saccharification: Material A enters a hydrothermal reactor and is mixed with steam to raise the temperature to 130°C. It then enters a holding column to maintain pressure and temperature for 25 minutes. The discharge temperature is then cooled to 95°C to obtain material B with a DE of 42.5.

[0125] (3) Filtration: Add 5 wt% sodium carbonate solution to material B to adjust the pH to 4.8, then cool to 70°C, add powdered activated carbon and filter aid recovered from secondary filtration, and filter through plate and frame filtration. Collect the filtered supernatant to obtain material C;

[0126] (4) Secondary decolorization and filtration: Add powdered activated carbon and filter aid to material C, filter it into a plate and frame filter, and collect the filtered clear liquid to obtain material D;

[0127] (5) Ion exchange: Material D was refined by hydrogen-type strong acid cation exchange resin and hydroxide-type strong base anion exchange resin. The syrup temperature in the ion exchange column was 45°C. A two-stage ion exchange process was used. The strong acid cation exchange resin was regenerated with 5% hydrochloric acid, and the hydroxide-type strong base anion exchange resin was regenerated with 4 wt% sodium hydroxide. The discharged material was collected to obtain material E.

[0128] (6) pH adjustment and filtration: Add powdered activated carbon and filter aid to material E and keep it warm at 65°C. Add 5 wt% sodium carbonate solution to adjust the pH to 5.0, filter it through plate and frame filtration, and collect the filtered supernatant to obtain material F;

[0129] (7) Material F is concentrated to obtain an acid starch syrup product.

[0130] Comparative Example 4

[0131] A method for preparing acid starch syrup comprises the following steps:

[0132] (1) Slurry preparation: RO pure water and corn starch were slurried to 17° Bé, and the pH was adjusted to 1.8 with 5 wt% food-grade hydrochloric acid to obtain material A;

[0133] (2) Saccharification: Material A enters a hydrothermal reactor and is mixed with steam to raise the temperature to 125°C. It then enters a holding column to maintain pressure and temperature for 30 minutes. The discharge temperature is then cooled to 95°C to obtain material B with a DE of 43.4.

[0134] (3) Filtration: Add 5% sodium carbonate solution to material B to adjust the pH to 4.8, then cool to 70°C, add powdered activated carbon and filter aid recovered from secondary filtration, and filter through plate and frame filtration. Collect the filtered supernatant to obtain material C;

[0135] (4) Secondary decolorization and filtration: Add powdered activated carbon and filter aid to material C, filter it into a plate and frame filter, and collect the filtered clear liquid to obtain material D;

[0136] (5) Ion exchange: Material D was refined by hydrogen-type strong acid cation exchange resin and hydroxide-type strong base anion exchange resin. The syrup temperature in the ion exchange column was 45°C. A two-stage ion exchange process was used. The strong acid cation exchange resin was regenerated with 5 wt% hydrochloric acid, and the hydroxide-type strong base anion exchange resin was regenerated with 4 wt% sodium hydroxide. The discharged materials were collected to obtain material E.

[0137] (6) pH adjustment and filtration: Add powdered activated carbon and filter aid to material E and keep it warm at 65°C. Add 5 wt% sodium carbonate solution to adjust the pH to 5.1. Filter the material through plate and frame filtration and collect the filtered supernatant to obtain material F.

[0138] (7) Material F is concentrated to obtain an acid starch syrup product.

[0139] Performance Testing

[0140] 1. Saccharification liquid quality test

[0141] The quality of the acid-process starch hydrolysis saccharification liquid of Examples 1-3 and Comparative Examples 1-4 was tested. Specifically, material B was taken and the pH was adjusted to 4.8 with 5wt% soda ash solution, and then the temperature was raised to 85°C and filtered with neutral filter paper. The clear liquid was collected and the dry matter, pH, and conductivity of the clear liquid were detected according to the "Quality Requirements for Starch Sugars Part 2: Glucose Syrup (Powder) GBT 20882.2-2021"; the clear liquid was vacuum concentrated in a 70°C water bath to a dry matter content of 50-51% (mass fraction), and the chroma of the sugar solution was determined according to the colorimetric determination method of "Quality Requirements for Starch Sugars Part 4: Fructose Syrup GBT 20882.4-2021". The results are shown in Table 1.

[0142] Table 1: Quality test results of material B of Examples 1-3 and Comparative Examples 1-4

[0143] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Dry matter / % 31.6 31.8 31.5 31.5 31.8 31.3 31.5 pH 4.8 4.8 4.8 4.8 4.8 4.8 4.8 Conductivity / μS / cm 660 630 680 2150 2110 1420 1450 Chroma / RBU 20.6 20.3 20.8 29.2 29.4 24.5 24.3

[0144] As can be seen from Table 1, the conductivity and chroma of the material B of Examples 1-3 of the present invention are lower than the conductivity and chroma of the material B obtained in Comparative Examples 1-4, indicating that the quality of the material B obtained by the preparation method of Examples 1-3 is better than the quality of the material B obtained by the preparation method of Comparative Examples 1-4.

[0145] 2. Ion exchange resin column sugar multiple test

[0146] The sugar pass ratios of the ion exchange resin columns of Examples 1-3 and Comparative Examples 1-4 were tested, and the results are shown in Table 2.

[0147] Table 2: Sugar excretion ratios of ion exchange resin columns of Examples 1-3 and Comparative Examples 1-4

[0148]

[0149] Note: Bed Volume (BV) refers to the volume of sugar solution that can be processed per unit volume of resin, usually expressed as BV (e.g. 1BV = 1 times the resin bed volume of sugar solution).

[0150] As can be seen from Table 2, when preparing acid-process syrups using the preparation methods of Examples 1-3 of the present invention, the ion exchange resin has a higher sugar conversion rate than that of Comparative Examples 1-4, indicating that the preparation method of the acid-process starch sugar of the present invention can increase the ion exchange resin sugar conversion rate.

[0151] Compared with Comparative Example 1-2, Example 1-3 uses RO purified water, followed by further cation removal, to obtain acidic pure water for slurry conditioning. This reduces the ash content of the starch slurry, reduces undesirable products during the high-temperature starch hydrolysis and saccharification process, and further reduces the amount of soda ash required to adjust the pH of the acid-processed starch hydrolysis saccharification liquid. Furthermore, the use of a weak base anion exchange resin for adsorption deacidification instead of soda ash to adjust the pH of the acid-processed starch hydrolysis saccharification liquid further reduces the ash content of the saccharification liquid. Based on these two factors, the ash content of the saccharification liquid in Example 1-3 is lower than that in Comparative Example 1-2, resulting in the ion exchange resin column in Example 1-3 having a higher sugar conversion ratio.

[0152] Compared with Comparative Examples 3-4, Example 1-3 adopts a softening and refining process using a sodium-type strong acid cation exchange resin column and a chloride-type strong base anion exchange resin column. Only the divalent and higher cations and anions in the sugar solution undergo ion exchange with the sodium ions on the cation exchange resin and the chloride ions on the anion exchange resin, and the sodium ions and chloride ions removed by ion exchange enter the sugar solution. Comparative Examples 3-4 adopt a desalting and refining process using a hydrogen-type strong acid cation exchange resin column and a weak base anion exchange resin column. The monovalent and higher cations and anions in the sugar solution are removed during the ion exchange process. Therefore, the ion exchange resin columns of Examples 1-3 have a higher sugar passivation ratio.

[0153] 3. Finished syrup quality test

[0154] The quality of the finished syrups prepared in Examples 1-3 and Comparative Examples 1-4 was tested. The specific method was as follows: the finished syrups prepared in Examples 1-3 and Comparative Examples 1-4 were respectively diluted to 50% dry matter, and the conductivity was measured; the color of the finished syrup was detected in accordance with the "Starch Sugar Quality Requirements Part 4: Fructose Syrup GBT 20882.4-2021", and the color of the finished syrup was detected after being placed at room temperature for 6 months. The results are shown in Table 3.

[0155] Table 3: Quality test results of finished syrups of Examples 1-3 and Comparative Examples 1-4

[0156]

[0157] As can be seen from Table 3, the conductivity of the acid-processed syrup produced using the acid-processed starch sugar preparation methods of Examples 1-3 of the present invention is lower than that of the finished syrup obtained in Comparative Examples 1-2, indicating that the quality of the finished syrup obtained using the acid-processed starch sugar preparation methods provided in Examples 1-3 of the present invention is superior to that of the syrup obtained in Comparative Examples 1-2. The chromaticity of the finished acid-processed syrups of Examples 1-3 of the present invention and the chromaticity of the acid-processed syrups of Examples 1-3 after storage at room temperature for 6 months are both lower than that of the finished syrups of Comparative Examples 3-4, indicating that the quality of the finished syrups obtained using the acid-processed starch sugar preparation methods provided in Examples 1-3 of the present invention is superior to that of Comparative Examples 3-4.

[0158] In summary, the present invention uses RO pure water to pass through a strong acid cation exchange resin to prepare acidic pure water for slurry adjustment, thereby reducing the amount of inorganic acid added for adjusting the pH of the slurry, and further reducing the amount of alkali added for adjusting the pH of the acid-processed starch hydrolysis saccharification liquid in the subsequent process, thereby reducing the ash content of the starch hydrolysis saccharification liquid; a weak base anion exchange resin column is used to perform adsorption deacidification on the starch hydrolysis saccharification liquid, instead of adding alkali to adjust the pH of the starch hydrolysis saccharification liquid, thereby reducing the ash content of the starch hydrolysis saccharification liquid; through the above two technical conditions, the ash content of the starch hydrolysis saccharification liquid is controlled at a low level, and then a softening and refining process of a sodium-type strong acid cation exchange resin column and a chloride-type strong base anion exchange resin column is used to replace the desalting and refining process of a hydrogen-type strong acid cation exchange resin column and a weak base anion exchange resin column, which greatly improves the sugar passing multiple of the ion exchange resin, thereby reducing the consumption of the ion exchange resin regeneration agent, and can obtain high-quality acid-processed starch sugar that is not easy to change color during product storage.

[0159] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing acid starch syrup, characterized in that: The following steps are involved: (1) Pure water is passed through a strong acid cation exchange resin column to obtain acidic pure water; the acidic pure water is mixed with starch and slurried to obtain material A; (2) The material A obtained in step (1) is heated, pressure-maintained, heat-maintained, and cooled to obtain material B; the pH of the material B is adjusted to acidic, filtered, and the filtrate is collected to obtain material C; (3) The material C obtained in step (2) is deacidified by a weak base anion exchange resin column to obtain material D; the pH of the material D is adjusted to acidic to obtain material E; (4) The material E obtained in step (3) is sequentially refined by a sodium-type strong acid cation exchange resin column and a chloride-type strong base ion exchange resin column to obtain material F; then refined by an activated carbon column to obtain material G, and the material G is concentrated to obtain acid-process starch syrup.

2. The preparation method according to claim 1, characterized in that In step (1), the pure water is pure water treated by reverse osmosis technology, the conductivity of the pure water is 5-30 μS / cm, and the pH of the pure water is 5.0-7.

0.

3. The preparation method according to claim 1, characterized in that In step (1), the strong acid cation exchange resin column is a hydrogen-type strong acid cation exchange resin column; and / or the pH of the acidic pure water is 3.0-4.5; and / or the strong acid cation exchange resin column is regenerated using a hydrochloric acid solution.

4. The preparation method according to claim 1, characterized in that In step (1), the slurry adjustment is to adjust the concentration of the slurry after the starch and acidic pure water are mixed to 16-20 degrees Baume; and / or, the slurry adjustment also includes a process of adjusting the pH to acidic.

5. The preparation method according to claim 1, characterized in that In step (2), the heating process includes: placing the material A into a hydroheater and mixing it with steam to heat it; and / or, the insulation temperature is 120-140°C; and / or, the insulation time is 15-40 minutes; and / or, the temperature corresponding to the cooling is 80-100°C.

6. The preparation method according to claim 1, characterized in that In step (2), the pH is adjusted to 2.5-3.5; and / or, a cooling process is included before filtration, and the temperature corresponding to the cooling is 65-80° C.; and / or, a ceramic membrane is used for filtration.

7. The preparation method according to claim 1, characterized in that In step (3), the temperature of the syrup in the weak base anion exchange resin column is 40-50° C.; and / or the discharge pH of the weak base anion exchange resin column is 4.0-6.0; and / or the weak base anion exchange resin column is regenerated with a sodium hydroxide solution, and the discharge is collected to obtain the material D; and / or the pH of the material D is adjusted to 4.0-6.

0.

8. The preparation method according to claim 1, characterized in that In step (4), the syrup temperature in the sodium-type strong acid cation exchange resin column and the chloride-type strong base ion exchange resin column is 40-50°C; and / or, the sodium-type strong acid cation exchange resin column and the chloride-type strong base ion exchange resin column are regenerated with sodium chloride solution, and the discharge is collected to obtain the material F.

9. The preparation method according to claim 1, characterized in that In step (4), the activated carbon column refining is granular activated carbon column refining, and the syrup temperature in the granular activated carbon column is 45-65°C.

10. Use of the preparation method according to any one of claims 1 to 9 in the field of preparing acid starch syrup.

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