NL2028609B1 - Method for preparing carbohydrate and polypeptide products from potato starch wastewater - Google Patents

Abstract

The present invention provides a method for preparing carbohydrate and polypeptide 5 products from potato starch wastewater, which mainly relates to a processing method for carbohydrates and polypeptides. The method comprises the following steps: successively filtering and concentrating potato starch wastewater to obtain a first solution; successively adding moderate-temperature amylase, saccharifying enzyme and neutral protease into the first solution for enzymatic hydrolysis three times to obtain a fourth solution; and successively subjecting the 10 fourth solution to high-temperature enzyme deactivation, concentration and spray drying to obtain products containing carbohydrates and polypeptides. By treating potato starch wastewater with bio-enzyme, the present invention solves the problems of treatment and discharge of potato starch wastewater, extracts organic substances in the wastewater and improves the utilization rate of resources.

Description

METHOD FOR PREPARING CARBOHYDRATE AND POLYPEPTIDE PRODUCTS FROM

POTATO STARCH WASTEWATER Technical Field The present invention relates to a method for processing carbohydrates and polypeptides, and particularly relates to a method for preparing carbohydrate and polypeptide products from potato starch wastewater. Background The potato starch processing industry in China has developed rapidly in recent years. According to surveys, there are more than 2,000 starch production enterprises in China at present, the total annual processing amount of potato is up to 8 million tons, among which the processing capacity of potato starch is more than 1.2 million tons. There are three main products in the production process of potato starch: main product. potato starch; by-products: potato residue and production wastewater. The treatment process of the potato residue is very simple and is not easy to cause pollution. Because of containing a large amount of organic compounds such as protein, carbohydrate, etc. and also containing a plurality of starch particles, fibres and nutrient substances such as potassium, phosphorus, calcium, etc., potato starch wastewater needs to be treated by means of the wastewater treatment process before being discharged.

Water-quality constituents of the potato starch wastewater are as follows: COD (Chemical Oxygen Demand): about 10000-25000mg/L; BOD (Biochemical Oxygen Demand): about 5000- 12000mg/L; SS (Suspended Solids): about 5000-10000mg/L. More than 20 million tons of acidic and high-concentration organic wastewater (potato starch wastewater for short) are discharged from potato starch processing every year. The potato starch wastewater has the main characteristics of high concentration of organic substances; (2) high B/C value which can be used for biochemical treatment; (3) weak acidity, namely, the pH is 4-6 in general; and (4) distinct seasonality, i.e. mainly appearing from September to December, and low wastewater temperature. In view of the characteristics, the process of treating potato starch wastewater by means of a common biochemical method is complicated, the treatment is not thorough, the treatment costs are relatively high, and thus the loss of organic substances in the potato starch wastewater is caused.

Summary The purpose of the present invention is to provide a method for preparing carbohydrate and polypeptide products from potato starch wastewater, which can simplify a preparation process, reduce treatment costs, recover organic substances in potato starch wastewater, and improve the utilization rate of potato starch wastewater resources.

To solve the technical problem, the present invention adopts the following technical solution:

The present invention provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: successively filtering and concentrating potato starch wastewater to obtain a first solution; adjusting the pH of the first solution to 5.5-7.0, adding moderate-temperature amylase, heating, and conducting first enzymatic hydrolysis to obtain a second solution; cooling the second solution, adding saccharifying enzyme, and conducting second enzymatic hydrolysis to obtain a third solution; cooling the third solution, adjusting the pH to 6.5-7.5, adding neutral protease, and conducting third enzymatic hydrolysis to obtain a fourth solution; and subjecting the fourth solution to high-temperature enzyme deactivation, evaporation and concentration, and then subjecting same to spray drying.

The method for preparing carbohydrate and polypeptide products from potato starch wastewater in embodiments of the present invention has the advantageous effects that: the method for treating potato starch wastewater is simple, the potato starch wastewater is filtered and concentrated in sequence, and the sediment and large-particle insoluble substances in the wastewater are removed to obtain a first solution; the first solution is subjected to enzymatic hydrolysis three times to obtain a fourth solution containing small molecular substances; and the fourth solution is subjected to evaporation, condensation and drying to obtain recovered products. By treating potato starch wastewater by means of enzymatic hydrolysis three times, the present invention rapidly and effectively reduces biochemical oxygen demand in the wastewater and the treatment costs for the potato starch wastewater, and in addition, realizes recycling of organics in the potato starch wastewater.

Detailed Description To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and fully described below. Experimental methods in which specific conditions are not specified in the embodiment are carried out under conventional conditions or as recommended by the manufacturer. The reagents or instruments used of which the manufacturers are not specified are all conventional products that can be purchased commercially.

A preparation method for nickel-plated graphene in embodiments of the present invention is specifically described below.

Embodiments of the present invention provide a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: S1. Successively filtering and concentrating potato starch wastewater to obtain a first solution.

Further, for the potato starch wastewater, the residual sediment and large-particle insoluble substances in the wastewater are removed by a plate and frame filter, a clear solution is obtained,

and then is concentrated by a nanofiltration membrane device to obtain a first solution. At this moment, the mass percentage of the solid matter in the first solution is 2-5%.

It should be noted that for the plate and frame filter here, the number of layers of filter membrane or filter plate thereof may be adjusted according to the concentration, viscosity and dregginess of the potato starch wastewater so as to achieve the effect of solid-liquid separation. In addition, a nanofiltration (NF) membrane is between a reverse osmosis (RO) membrane and an ultrafiltration (UF) membrane, in general, the reverse osmosis membrane has a high desalting rate for almost all solutes, but the nanofiltration membrane only has a high desalting rate for specific solutes. On the one hand, the nandfiltration membrane device can remove the inorganic salt ions in a low valence state to intercept the trace elements in a high valence state in the wastewater. On the other hand, the nanofiltration membrane device can intercept organics such as starch, polypeptide, amino acid, etc. in the wastewater, thereby further improving the recovery rate of organics and trace elements in the wastewater.

S2. Adjusting the pH of the first solution to 5.5-7.0, adding moderate-temperature amylase, heating, and conducting first enzymatic hydrolysis to obtain a second solution.

Further, in the embodiment provided by the present invention, the pH of the first solution is adjusted by 8-12mol/L sodium hydroxide solution. It should be noted that the potato starch wastewater is more acidic, which is not conducive to the subsequent enzymatic hydrolysis, so there is a need to appropriately adjust the pH of the first solution. Moreover, the concentration range of the sodium hydroxide solution is not limited thereto, and sodium hydroxide solutions within other concentration ranges can also be selected. In addition, other types of alkaline solutions such as sodium carbonate solution, potassium hydroxide solution, etc. can also be selected to achieve the purpose of adjusting the pH of the first solution.

Further, the usage amount of the moderate-temperature amylase is 0.01-0.1%0 of the weight of the potato starch wastewater, the temperature of the first enzymatic hydrolysis is 80-90°C, and the time duration is 0.5-2h. In general, the content of starch in the potato starch wastewater is 2- 5%, the usage amount of the moderate-temperature amylase is calculated according to the content range of the starch in the potato starch wastewater, so it can be guaranteed that the moderate-temperature amylase reacts with the substrate more thoroughly in a certain period of time, on the other hand, costs for wastewater treatment are saved. Moderate-temperature amylase, also called moderate-temperature a-amylase, can hydrolyze starch, soluble dextrin and other substances, and can rapidly reduce the viscosity of the gelatinized starch, the hydrolysis products including dextrin, a small amount of glucose and maltose, etc. It should be noted that moderate-temperature amylase in an activity unit of 2000u/g is selected here, moderate- temperature amylase in activity units of 3000u/g, 4000u/g and 6000u/g can also be selected, in addition, moderate-temperature amylase broths of corresponding specifications can also be selected, and the specific usage amount of these moderate-temperature amylase is calculated according to the content of starch in the potato starch wastewater..

S3. Cooling the second solution, adding saccharifying enzyme, and conducting second enzymatic hydrolysis to obtain a third solution.

Further, the usage amount of the saccharifying enzyme is 0.005-0.1%0 of the weight of the potato starch wastewater, the temperature of the second enzymatic hydrolysis is 50-65°C, and the time duration is 1-2h.

Saccharifying enzyme, also known as glucoamylase, has a scientific name of a-1,4-Glucan glucohydrolace. Saccharifying enzyme can hydrolyze a-1,4 glucoside bonds from the non- reducing end of starch to produce glucose, can slowly hydrolyze a-1,6 glucoside bonds to convert same into glucose; and can hydrolyze dextrin to release B-D-glucose from the non-reducing end of glycogen. The second solution contains a large amount of dextrin and starch which is not converted, and saccharifying enzyme is added to conduct enzymatic hydrolysis on the second solution so the dextrin and starch may be converted into glucose. It should be noted that the dextrin and starch which is not converted in the potato starch wastewater are calculated according to the content of starch. Moreover, the optimum temperature of the saccharifying enzyme is 50- 85°C, so the saccharifying enzyme fully reacts with the substrate within short time. In addition, a saccharifying enzyme broth in an activity unit of 100000u/mL is selected here, saccharifying enzyme in an activity unit of 200000u/mL(u/g) or 260000u/mL(u/g) can also be selected, and the specific usage amount thereof may be calculated according to the content of starch in the potato starch wastewater.

S4. Cooling the third solution, adjusting the pH to 6.5-7.5, adding neutral protease, and conducting third enzymatic hydrolysis to obtain a fourth solution.

Further, the usage amount of the neutral protease is 0.02-0.1%o of the weight of the potato starch wastewater, the temperature of the third enzymatic hydrolysis is 50-60°C, and the time duration is 2-4h.

The content of protein in the potato starch wastewater is 0.2-0.5%, the specific weight of protein can be calculated according to the weight of the potato starch wastewater, the usage amount thereof is calculated according to the activity unit of the neutral protease, a reaction is conducted at the optimum temperature of the neutral protease, and the usage amount of the neutral protease is controlled while guaranteeing the reaction efficiency.

Further, in the embodiment provided by the present invention, the pH of the third solution is adjusted by 8-12mol/L sodium hydroxide solution. It should be noted that the glucose solution is acidic, which is not conducive to the subsequent enzymatic hydrolysis of the neutral protease, so there is a need to appropriately adjust the pH of the third solution. Moreover, the concentration range of the sodium hydroxide solution is not limited thereto, and the sodium hydroxide solutions within other concentration ranges can also be selected. In addition, other types of alkaline solutions such as sodium carbonate solution, potassium hydroxide solution, etc. can also be selected to achieve the purpose of adjusting the pH of the third solution.

The neutral protease can hydrolyze large molecular protein in the third solution into polypeptide, amino acid and other products at certain temperature and pH, so as to facilitate the recovery and utilization of organics in the third solution. It should be noted that neutral protease in an activity unit of 50,00u/g is selected here, neutral protease in different activity units can also 5 be selected according to the actual production situation, and the specific usage amount thereof is calculated according to the content of protein in the potato starch wastewater.

The fourth solution is subjected to high-temperature enzyme deactivation, evaporation and concentration, and then is subjected to spray drying. Specifically, the fourth solution is heated to 95-100°C for 0.3-1h, so the previously added moderate-temperature amylase, saccharifying enzyme and neutral protease are deactivated, the fourth solution after enzyme deactivation is pumped into a multi-effect falling film evaporator and concentrated to a situation where the mass percentage of solid matter is 20-30%, and is introduced into a spray dryer for spray drying. Enzymes can be deactivated at high temperature so that the moderate-temperature amylase, saccharifying enzyme and neutral protease which are subjected to enzymatic hydrolysis are deactivated before products are obtained, thereby guaranteeing the quality of subsequent products.

The features and performance of the present invention are further described below in detail in combination with the embodiments.

Embodiment 1 This embodiment provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: Filtering the potato starch wastewater by a plate and frame filter, concentrating the filtered potato starch wastewater by a nanofiltration membrane device to a situation where the content of solid matter is 2%, pumping the concentrated potato starch wastewater into an enzymolysis pot; adding an appropriate amount of 8mol/L sodium hydroxide solution, adjusting the pH to 5.5, adding moderate-temperature amylase of which the mass is 0.01% of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 2h at 90°C and then cooling to 65°C; adding a saccharifying enzyme broth of which the mass is 0.005%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 2h and then cooling to 55°C; adding an appropriate amount of 10mol/L sodium hydroxide solution, adjusting the pH to 7.5, adding neutral protease of which the mass is 0.02%. of the weight of the potato starch wastewater and then conducting enzymatic hydrolysis for 4h, obtaining a hydrolysis product.

Heating to 95°C for 1h, conducting enzyme deactivation, pumping the hydrolysis product into a multi-effect falling film evaporator, concentrating to a situation where the mass percentage of solid matter is 20%, and conducting spray drying to obtain a product.

Embodiment 2 This embodiment provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: Filtering the potato starch wastewater by a plate and frame filter, concentrating the filtered potato starch wastewater by a nanofiltration membrane device to a situation where the content of solid matter is 3%, pumping the concentrated potato starch wastewater into an enzymolysis pot; adding an appropriate amount of 10mol/L sodium hydroxide solution, adjusting the pH to 6.0, adding moderate-temperature amylase of which the mass is 0.025%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 1h at 85°C and then cooling to 55°C; adding a saccharifying enzyme broth of which the mass is 0.015%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 1h and then cooling to 50°C; adding an appropriate amount of 12mol/L sodium hydroxide solution, adjusting the pH to 7.0, adding neutral protease of which the mass is 0.04%. of the weight of the potato starch wastewater and then conducting enzymatic hydrolysis for 3h, obtaining a hydrolysis product.

Heating to 98°C for 0.5h, conducting enzyme deactivation, pumping the hydrolysis product into a multi-effect falling film evaporator, concentrating to a situation where the mass percentage of solid matter is 25%, and conducting spray drying to obtain a product.

Embodiment 3 This embodiment provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: Filtering the potato starch wastewater by a plate and frame filter, concentrating the filtered potato starch wastewater by a nanofiltration membrane device to a situation where the content of solid matter is 5%, pumping the concentrated potato starch wastewater into an enzymolysis pot; adding an appropriate amount of 12mol/L sodium hydroxide solution, adjusting the pH to 6.5, adding moderate-temperature amylase of which the mass is 0.04%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 0.5h at 80°C and then cooling to 55°C; adding a saccharifying enzyme broth of which the mass is 0.03%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 1h and then cooling to 50°C; adding an appropriate amount of 10mol/L sodium hydroxide solution, adjusting the pH to 7.5, adding neutral protease of which the mass is 0.06%. of the weight of the potato starch wastewater and then conducting enzymatic hydrolysis for 2h, obtaining a hydrolysis product.

Heating to 100°C for 0.3h, conducting enzyme deactivation, pumping the hydrolysis product into a multi-effect falling film evaporator, concentrating to a situation where the mass percentage of solid matter is 30%, and conducting spray drying to obtain a product.

Embodiment 4 This embodiment provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: Filtering the potato starch wastewater by a plate and frame filter, concentrating the filtered potato starch wastewater by a nanofiltration membrane device to a situation where the content of solid matter is 3%, pumping the concentrated potato starch wastewater into an enzymolysis pot; adding an appropriate amount of 10mol/L sodium hydroxide solution, adjusting the pH to 7.0, adding moderate-temperature amylase of which the mass is 0.06%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 0.5h at 80°C and then cooling to 55°C; adding a saccharifying enzyme broth of which the mass is 0.005%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 2h and then cooling to 50-55°C; adding an appropriate amount of 10mol/L sodium hydroxide solution, adjusting the pH to 7.0, adding neutral protease of which the mass is 0.08%. of the weight of the potato starch wastewater and then conducting enzymatic hydrolysis for 2h, obtaining a hydrolysis product.

Heating to 98°C for 0.5h, conducting enzyme deactivation, pumping the hydrolysis product into a multi-effect falling film evaporator, concentrating to a situation where the mass percentage of solid matter is 22%, and conducting spray drying to obtain a product.

Embodiment 5 This embodiment provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: Filtering the potato starch wastewater by a plate and frame filter, concentrating the filtered potato starch wastewater by a nanofiltration membrane device to a situation where the content of solid matter is 3%, pumping the concentrated potato starch wastewater into an enzymolysis pot; adding an appropriate amount of 8mol/L sodium hydroxide solution, adjusting the pH to 5.5, adding moderate-temperature amylase of which the mass is 0.08%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 0.5h at 85°C and then cooling to 53°C; adding a saccharifying enzyme broth of which the mass is 0.07%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 2h and then cooling to 50°C; adding an appropriate amount of 12mol/L sodium hydroxide solution, adjusting the pH to 6.5, adding neutral protease of which the mass is 0.1%o of the weight of the potato starch wastewater and then conducting enzymatic hydrolysis for 3h, obtaining a hydrolysis product.

Heating to 100°C for 0.4h, conducting enzyme deactivation, pumping the hydrolysis product into a multi-effect falling film evaporator, concentrating to a situation where the mass percentage of solid matter is 24%, and conducting spray drying to obtain a product.

Embodiment 6 This embodiment provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: Filtering the potato starch wastewater by a plate and frame filter, concentrating the filtered potato starch wastewater by a nanofiltration membrane device to a situation where the content of solid matter is 4%, pumping the concentrated potato starch wastewater into an enzymolysis pot; adding an appropriate amount of 9mol/L sodium hydroxide solution, adjusting the pH to 5.8, adding moderate-temperature amylase of which the mass is 0.1%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 2h at 80°C and then cooling to 60°C; adding a saccharifying enzyme broth of which the mass is 0.1%o of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 1h and then cooling to 53°C; adding an appropriate amount of 11mol/L sodium hydroxide solution, adjusting the pH to 6.8, adding neutral protease of which the mass is 0.1%. of the weight of the potato starch wastewater and then conducting enzymatic hydrolysis for 2h, obtaining a hydrolysis product.

Heating to 99°C for 0.6h, conducting enzyme deactivation, pumping the hydrolysis product into a multi-effect falling film evaporator, concentrating to a situation where the mass percentage of solid matter is 28%, and conducting spray drying to obtain a product.

Embodiment 7 This embodiment provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: Filtering the potato starch wastewater by a plate and frame filter, concentrating the filtered potato starch wastewater by a nanofiltration membrane device to a situation where the content of solid matter is 3%, pumping the concentrated potato starch wastewater into an enzymolysis pot; adding an appropriate amount of 11mol/L sodium hydroxide solution, adjusting the pH to 6.8, adding moderate-temperature amylase of which the mass is 0.01%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 0.5h at 88°C and then cooling to 59°C; adding a saccharifying enzyme broth of which the mass is 0.005%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 1h and then cooling to 53°C; adding an appropriate amount of Smol/L sodium hydroxide solution, adjusting the pH to 7.0, adding neutral protease of which the mass is 0.04%. of the weight of the potato starch wastewater and then conducting enzymatic hydrolysis for 2h, obtaining a hydrolysis product.

Heating to 100°C for 0.4h, conducting enzyme deactivation, pumping the hydrolysis product into a multi-effect falling film evaporator, concentrating to a situation where the mass percentage of solid matter is 25%, and conducting spray drying to obtain a product.

Embodiment 8 This embodiment provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: Filtering the potato starch wastewater by a plate and frame filter, concentrating the filtered potato starch wastewater by a nanofiltration membrane device to a situation where the content of solid matter is 3%, pumping the concentrated potato starch wastewater into an enzymolysis pot; adding an appropriate amount of 10mol/L sodium hydroxide solution, adjusting the pH to 5.5, adding moderate-temperature amylase of which the mass is 0.025%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 0.5h at 85°C and then cooling to 60°C; adding a saccharifying enzyme broth of which the mass is 0.015%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 1h and then cooling to 50°C; adding an appropriate amount of 10mol/L sodium hydroxide solution, adjusting the pH to 7.0, adding neutral protease of which the mass is 0.02%. of the weight of the potato starch wastewater and then conducting enzymatic hydrolysis for 2h, obtaining a hydrolysis product.

Heating to 100°C for 0.3h, conducting enzyme deactivation, pumping the hydrolysis product into a multi-effect falling film evaporator, concentrating to a situation where the mass percentage of solid matter is 25%, and conducting spray drying to obtain a product.

Embodiment 9 This embodiment provides a method for preparing carbohydrate and polypeptide products from potato starch wastewater, comprising the following steps: Filtering the potato starch wastewater by a plate and frame filter, concentrating the filtered potato starch wastewater by a nanofiltration membrane device to a situation where the content of solid matter is 3%, pumping the concentrated potato starch wastewater into an enzymolysis pot; adding an appropriate amount of 10mol/L sodium hydroxide solution, adjusting the pH to 6.0, adding moderate-temperature amylase of which the mass is 0.03%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 0.5h at 85°C and then cooling to 60°C; adding a saccharifying enzyme broth of which the mass is 0.02%. of the weight of the potato starch wastewater, conducting enzymatic hydrolysis for 1h and then cooling to 50°C; adding an appropriate amount of 10mol/L sodium hydroxide solution, adjusting the pH to 6.5, adding neutral protease of which the mass is 0.03%. of the weight of the potato starch wastewater and then conducting enzymatic hydrolysis for 2h, obtaining a hydrolysis product.

Heating to 100°C for 0.3h, conducting enzyme deactivation, pumping the hydrolysis product into a multi-effect falling film evaporator, concentrating to a situation where the mass percentage of solid matter is 25%, and conducting spray drying to obtain a carbohydrate and polypeptide product.

The constituents of the carbohydrate and polypeptide products obtained in the above embodiments mainly comprise glucoses, amino acids, small molecular peptide substances and trace elements. The mass percentage of the glucoses measured by means of the glucose oxidase method is 35-45%, the mass percentage of the amino acids measured by means of the ninhydrin colorimetric method is 35-45%, the mass percentage of the trace elements measured by means of a plasma spectrometer is 5-12%, the mass percentage of moisture measured by means of a moisture meter is 8-12%, and the mass percentage of other substances is 1.5-4%.

In conclusion, the method for treating potato starch wastewater is simple, the potato starch wastewater is filtered and concentrated in sequence, and the sediment and large-particle insoluble substances in the wastewater are removed to obtain a first solution; the first solution is subjected to enzymatic hydrolysis three times to obtain a fourth solution containing small molecular substances; and the fourth solution is subjected to evaporation, condensation and drying to obtain recovered products. By treating potato starch wastewater by means of enzymatic hydrolysis three times, the present invention rapidly and effectively reduces biochemical oxygen demand in the wastewater and the treatment costs for the potato starch wastewater, and in addition, realizes recycling of organics in the potato starch wastewater.

The embodiments described above are part of the embodiments of the present invention, not all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed present invention, and merely represents the selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those ordinary skilled in the art without contributing creative labour will belong to the protection scope of the present invention.

Claims (9)

CONCLUSIONS A method for the preparation of carbohydrate and polypeptide products from potato starch waste water, comprising the steps of: - sequentially filtering and concentrating potato starch waste water to obtain a first solution; - adjusting the pH of the first solution to 5.5 - 7.0, adding a moderate temperature active amylase, heating and performing a first enzymatic hydrolysis to obtain a second solution; - cooling the second solution, adding saccharifying enzyme and performing a second enzymatic hydrolysis to obtain a third solution; - cooling the third solution, adjusting the pH to 6.5-7.5, adding neutral protease and performing a third enzymatic hydrolysis to obtain a fourth solution; and - subjecting the fourth solution to enzyme inactivation at high temperature, evaporation and concentration, and then subjecting it to spray drying. The method for preparing carbohydrate and polypeptide products from potato starch waste water according to claim 1, wherein the temperature of the first enzymatic hydrolysis is 80-90°C, and the time is 0.5-2 hours. The process for preparing carbohydrate and polypeptide products from potato starch waste water according to claim 1, wherein the temperature of the second enzymatic hydrolysis is 50-65°C and the time is 1-2 hours. The process for preparing carbohydrate and polypeptide products from potato starch waste water according to claim 1, wherein the temperature of the third enzymatic hydrolysis is 50 - 60°C and the time is 2 - 4 hours. The method for preparing carbohydrate and polypeptide products from potato starch waste water according to claim 1, wherein the amount of moderate temperature active amylase used, the amount of the saccharifying enzyme used and the amount of the neutral protease used are 0.01 - 0, respectively. 1%, 0.005 - 0.1% and 0.02 - 0.1% by weight of the potato starch waste water. The method for preparing carbohydrate and polypeptide products from potato starch wastewater according to claim 1, wherein the pH of the first solution and the third solution is adjusted by adding an alkaline solution, wherein the alkaline solution is 8-12 mol/L sodium hydroxide solution . The method for preparing carbohydrate and polypeptide products from potato starch waste water according to claim 1, wherein the mass percent solids of the first solution is 2-5%. The method for preparing carbohydrate and polypeptide products from potato starch wastewater according to claim 1, wherein the temperature of the high-temperature inactivation of the enzyme is 95-100°C, and the time of the high-temperature inactivation of the enzyme is 0. .3 - 1 hour. The process for preparing carbohydrate and polypeptide products from potato starch waste water according to claim 1, wherein the fourth solution after the enzyme inactivation is evaporated at a high temperature and concentrated to a situation where the mass percentage of solids is 20-30%.