CN111394409A

CN111394409A - Method for preparing syrup by enzymolysis of starch raw material

Info

Publication number: CN111394409A
Application number: CN202010173760.8A
Authority: CN
Inventors: 吴世林; 闫方权; 吕勇; 江华峰
Original assignee: Guangzhou Wisdom Bio Technology Co ltd
Current assignee: Guangzhou Wisdom Bio Technology Co ltd
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2020-07-10

Abstract

The invention relates to a method for preparing syrup by enzymolysis of starch raw materials. The method comprises the steps of size mixing enzymolysis, liquefaction, separation, saccharification, decoloration centrifugation, ion exchange and concentration, wherein one or more starch raw materials are subjected to enzymolysis to form a plurality of slow-release functional sugars with different relative molecular masses, and starch polysaccharides and non-starch polysaccharides in the starch raw materials are fully utilized to provide a high-quality sugar source for human bodies or animal organisms. The method has the advantages of high quality of residue produced in the preparation process, rich protein and fat, no resource waste and reduced environmental pollution. The syrup prepared by the method has high enzymolysis degree, the DE value of the syrup is more than or equal to 80 percent, the syrup content with the relative molecular mass of less than 1000Da is more than or equal to 95 percent, the syrup can effectively replace glucose, sucrose, lactose and the like in feed, has a certain antioxidation function and an immune function regulation function, reduces the diarrhea rate of young piglets and the like, and has good social and economic benefits.

Description

Method for preparing syrup by enzymolysis of starch raw material

Technical Field

The invention relates to a method for preparing syrup by enzymolysis of starch raw materials, and belongs to the technical field of deep processing of starch products.

Background

The starch raw materials comprise pea powder, corn powder, wheat powder, black bean powder, yam powder, potato powder, pumpkin powder, millet powder, sweet potato powder, cassava powder, sweet potato powder, lotus root starch, potato powder and the like. For example, the starch content of sweet potato powder is up to more than 80%. The starch sugar is prepared from grain, potato, bean, etc. containing starch by acid, acid enzyme or enzyme method, and comprises maltose, glucose, fructose, and glucose syrup. However, the starch material also contains partial non-starch polysaccharide, which is polysaccharide other than starch, mainly contains cellulose, hemicellulose, pectin and the like, and is the main component of feed fiber, and the fiber surrounds nutrient substances in cell walls, so that the normal digestive function of animals is inhibited, and the absorption of nutrition by the animals is prevented. Therefore, potential nutritional ingredients in the feed obtained after the starch raw material is processed are not fully utilized, and the existence of the non-starch polysaccharide can also cause the efficiency of the subsequent preparation of starch sugar to be reduced. In the traditional preparation of starch sugar, corn starch is mostly used as a raw material, and the residues after liquefaction contain protein, fat, ash, fiber and the like through processes of liquefaction, saccharification, concentration and the like, so that the nutritional ingredients in the residues are not fully utilized, the subsequent saccharification process is influenced, and the residues after the corn starch is extracted from corn (rich in protein, fat and non-starch polysaccharide) are not fully utilized.

Disclosure of Invention

In view of the above, there is a need to provide a method for preparing syrup by enzymolysis of starch raw material, which fully utilizes starch polysaccharide and non-starch polysaccharide in starch raw material, decomposes starch polysaccharide and non-starch polysaccharide into various slow-release functional sugars with different relative molecular masses, provides high-quality sugar sources for human body or animal body, is easy to absorb, improves metabolic energy, promotes growth of body, effectively replaces glucose, sucrose, lactose and the like in feed, has certain antioxidant function, regulates immunity, reduces diarrhea rate of young piglets and the like, separates high-quality residue (rich in protein and fat), increases resource utilization, reduces environmental pollution, and has good social and economic benefits.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing syrup by enzymolysis of starch raw materials comprises the following steps:

step (1), size mixing and enzymolysis, namely adding water into a starch raw material to prepare 20-30% of powder pulp, adjusting the pH to 3.0-6.0, adding a complex enzyme 1, and stirring at the temperature of 30-50 ℃ for 1-5 hours to obtain an enzymolysis solution, wherein the complex enzyme 1 is cellulase, hemicellulase, pectinase and α -galactosidase, and the addition amounts are 50-250U/g, 20-150U/g, 50-250U/g and 20-100U/g respectively;

liquefying, namely adjusting the pH of the enzymolysis liquid in the step (1) to 5.5-6.5, raising the temperature to 85-99 ℃, adding α -amylase with the addition of 10-30U/g, and stirring for 20-90 min to obtain a liquefied liquid;

and (3): separation: adjusting the pH of the liquefied liquid in the step (2) to 4.0-5.0, and performing centrifugal separation to obtain a precipitate and a supernatant; washing and centrifuging, washing the precipitate for 1-2 times by using water, and centrifuging to obtain residues and a washing solution; the centrifugal rotating speed and the centrifugal time are the same in the washing process, and washing liquid is combined for next size mixing; drying and remoistening the residue to obtain a product containing protein and fat, wherein the content of protein and fat is more than or equal to 85 percent, the content of protein is more than or equal to 55 percent, and the product can be used for preparing protein powder, oil products, high-protein feed additives and the like;

and (4): saccharification: adjusting the pH of the supernatant in the step (3) to 4.0-6.5, adding a complex enzyme 2, and stirring at 55-65 ℃ for 6-48 h to obtain a saccharification liquid;

and (5): decoloring and centrifuging: adding 1-2% of active carbon for sugar into the saccharified liquid obtained in the step (4), and stirring and decoloring for 20-60 min; centrifuging to obtain light clear saccharification liquid;

and (6): ion exchange: introducing the light clear saccharified liquid obtained in the step (5) into cation exchange resin and anion exchange resin in sequence, wherein the degree of hammering of the light clear saccharified liquid entering a resin column is 50-55, the flow rate is 1-3 VB/h, and the temperature is 50-60 ℃; obtaining ion exchange liquid;

and (7): concentration: and (4) injecting the ion exchange liquid obtained in the step (6) into vacuum concentration equipment for concentration to ensure that the water content is 25-30%.

Further, the starch raw material in the step (1) is at least one of high starch products such as pea powder, corn powder, wheat flour, black bean powder, yam powder, potato powder, pumpkin powder, millet powder, sweet potato powder, cassava powder, sweet potato powder, lotus root starch, potato powder and the like.

Further, iodine in the liquefied liquid in the step (2) reacts to form brownish red, and the DE value is 15-20%.

Further, the rotation speed of centrifugal separation in the step (3) is 1500-3000 r/min, and the centrifugal time is 2-10 min.

Further, the rotating speed of washing and centrifuging in the step (3) is 1500-3000 r/min, and the centrifuging time is 2-10 min; when the washing times are two, the rotating speed and time of the two washing centrifuges are the same.

Further, the centrifugal rotating speed in the step (5) is 1500-3000 r/min, and the centrifugal time is 2-10 min.

Further, the light transmittance of the ion exchange solution in the step (6) is more than or equal to 95%.

Further, the temperature of the vacuum concentration in the step (7) is 60-65 ℃, and the pressure is 0.075-0.085 MPa.

The syrup prepared by the invention has high purity, low viscosity, high sweetness, low molecular weight, easy absorption and utilization by organisms and high quality.

The invention has the beneficial effects that:

(1) the invention directly starts from the starch raw material to treat, fully utilizes resources and avoids the generation of waste materials.

(2) The DE value of the concentrated syrup is more than or equal to 80 percent, the content of the syrup with the relative molecular mass of less than 1000Da reaches 95 percent, the enzymolysis degree is deep, the product has high purity, small viscosity, high sweetness and small molecular weight, and the syrup is easy to be absorbed and utilized by organisms and has high quality.

(3) The residue separated by the method is rich in protein and fat, and is a high-quality resource after being dried and remoistened.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be further clearly and completely described below with reference to the embodiments of the present invention. It should be noted that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

step (1), size mixing and enzymolysis, namely adding water into pea meal to prepare 25 percent of powder pulp, adjusting the pH to 5, adding compound enzyme 1 (150U/g cellulase, 100U/g hemicellulase, 150U/g pectinase and 50U/g α -galactosidase), and stirring for 5 hours at 37 ℃ to obtain enzymolysis liquid;

liquefying, namely adjusting the pH of the enzymolysis liquid in the step (1) to 6.0, raising the temperature to 97 ℃, adding α -amylase in an amount of 24U/g, and stirring for 60min to obtain a liquefied liquid with a DE value of 18.5%;

and (3): separation: adjusting the pH value of the liquefied liquid in the step (2) to 4.2, and performing centrifugal separation at the centrifugal rotation speed of 2700r/min for 3min to obtain a precipitate and a supernatant; washing and centrifuging, washing the precipitate with water for 2 times, centrifuging at 2500r/min for 5min to obtain residue and washing solution; the centrifugal rotating speed and time of two times are the same in the washing process, and washing liquid is combined for next size mixing; drying and remoistening the residue to obtain a product containing protein and fat; the content of the residue protein is 82.5 percent, and the content of fat is 7.13 percent;

saccharifying, namely adjusting the pH of the supernatant obtained in the step (3) to 4.5, adding complex enzyme 2(β -amylase 280U/g, pullulanase 0.1ASPU/g and amyloglucosidase 250U/g), and stirring for 40 hours at the temperature of 60 ℃ to obtain a saccharified solution;

and (5): decoloring and centrifuging: adding 1% of active carbon for sugar into the saccharified liquid obtained in the step (4), and stirring and decoloring for 40 min; centrifuging at 2500r/min for 3min to remove impurities such as active carbon to obtain transparent and clear saccharified liquid;

and (6): ion exchange: introducing the light clear saccharified solution in the step (5) into cation exchange resin and anion exchange resin in sequence, wherein the brix of the saccharified solution entering a resin column is 55, the flow rate is 1.8VB/h, and the temperature is 55 ℃; removing impurities, particularly colored substances and ash in the saccharification liquid to obtain an ion exchange liquid with the light transmittance of 97.3%;

and (7): concentration: injecting the ion exchange liquid obtained in the step (6) into vacuum concentration equipment for concentration, wherein the temperature of vacuum concentration is 60 ℃, and the pressure is 0.081 MPa; the water content is 25 percent, and the proportion of the molecular weight of the formed syrup which is less than or equal to 1000 is up to 98.5 percent.

Example 2

step (1), size mixing and enzymolysis, namely adding water into corn flour to prepare 30 percent of powder pulp, adjusting the pH to 5.5, adding complex enzyme 1 (160U/g cellulase, 110U/g hemicellulase, 160U/g pectinase and 60U/g α -galactosidase), and stirring for 4 hours at 50 ℃ to obtain enzymatic hydrolysate;

liquefying, namely adjusting the pH of the enzymolysis liquid in the step (1) to 6.2, raising the temperature to 93 ℃, adding α -amylase in an amount of 20U/g, and stirring for 50min to obtain a liquefied liquid with a DE value of 17.3%;

and (3): separation: adjusting the pH of the liquefied liquid in the step (2) to 4.5, and performing centrifugal separation at the centrifugal rotation speed of 2500r/min for 4min to obtain a precipitate and a supernatant; washing and centrifuging, washing the precipitate with water for 1 time, centrifuging at 2600r/min for 2min to obtain residue and washing solution; the washing liquid is used for next size mixing; drying and remoistening the residue to obtain a product containing protein and fat; the content of the residual protein is 58.7 percent, and the content of fat is 30.2 percent;

saccharifying, namely adjusting the pH of the supernatant obtained in the step (3) to 5.0, adding complex enzyme 2(β -amylase 350U/g, pullulanase 0.3ASPU/g and amyloglucosidase 300U/g), and stirring for 30 hours at the temperature of 55 ℃ to obtain a saccharified solution;

and (5): decoloring and centrifuging: adding 1.5% of active carbon for sugar into the saccharified liquid obtained in the step (4), and stirring and decoloring for 30 min; centrifuging at 2300r/min for 5min to remove impurities such as active carbon to obtain light clear saccharified solution;

and (6): ion exchange: introducing the light clear saccharified liquid in the step (5) into cation exchange resin and anion exchange resin in sequence, wherein the weight of the saccharified liquid entering a resin column is 53, the flow rate is 2.5VB/h, and the temperature is 58 ℃; removing impurities, particularly colored substances and ash in the saccharification liquid to obtain ion exchange liquid with the light transmittance of 98.2%;

and (7): concentration: injecting the ion exchange solution obtained in the step (6) into vacuum concentration equipment for concentration, wherein the temperature of vacuum concentration is 63 ℃, and the pressure is 0.079 MPa; the water content is 27 percent, and the proportion of the molecular weight of the formed syrup which is less than or equal to 1000 is as high as 97.3 percent.

Example 3

step (1), size mixing and enzymolysis, namely adding water into pea meal, corn meal and sweet potato meal (the weight ratio is 1:1:1) to prepare 20% of flour slurry, adjusting the pH to 4.8, adding complex enzyme 1 (100U/g of cellulase, 80U/g of hemicellulase, 130U/g of pectinase and 40U/g of α -galactosidase), and stirring for 3 hours at the temperature of 45 ℃ to obtain an enzymolysis solution;

liquefying, namely adjusting the pH of the enzymolysis liquid in the step (1) to 5.6, raising the temperature to 95 ℃, adding α -amylase in an amount of 11U/g, and stirring for 40min to obtain a liquefied liquid with a DE value of 15.8%;

and (3): separation: adjusting the pH of the liquefied liquid in the step (2) to 4.3, and performing centrifugal separation at the centrifugal rotation speed of 2400r/min for 5min to obtain a precipitate and a supernatant; washing and centrifuging, washing the precipitate with water for 1 time, centrifuging at 2500r/min for 4min to obtain residue and washing solution; the washing liquid is used for next size mixing; drying and remoistening the residue to obtain a product containing protein and fat; the content of the residue protein is 74.2 percent, and the content of fat is 13.9 percent;

saccharifying, namely adjusting the pH of the supernatant obtained in the step (3) to 5.5, adding complex enzyme 2(β -210U/g amylase, 0.2ASPU/g pullulanase and 150U/g amyloglucosidase), and stirring for 24 hours at the temperature of 55 ℃ to obtain a saccharified solution;

and (5): decoloring and centrifuging: adding 1.3% of active carbon for sugar into the saccharification liquid obtained in the step (4), and stirring and decoloring for 35 min; centrifuging at 2800r/min for 3min to remove impurities such as active carbon to obtain light clear saccharified solution;

and (6): ion exchange: introducing the light clear saccharified solution in the step (5) into cation exchange resin and anion exchange resin in sequence, wherein the weight of the saccharified solution entering a resin column is 50, the flow rate is 1.5VB/h, and the temperature is 52 ℃; removing impurities, particularly colored substances and ash in the saccharification liquid to obtain ion exchange liquid with the light transmittance of 95.5%;

and (7): concentration: injecting the ion exchange solution obtained in the step (6) into vacuum concentration equipment for concentration, wherein the temperature of vacuum concentration is 65 ℃, and the pressure is 0.078 MPa; the water content is 28 percent, and the proportion of the molecular weight of the formed syrup which is less than or equal to 1000 is up to 96.2 percent.

To further verify the technical effect of the solution of the present invention, the following tests were performed on the syrup prepared according to the present invention:

(I) sensory testing

Evaluation indexes are as follows: randomly extracting 20 persons for sensory evaluation, wherein 10 men and 10 women respectively score the sweet taste value, the color, the smell and the state, the score is 1-10, the highest score is 10, the lowest score is 1, and the average value is the final score.

The test was divided into 7 groups, which were syrup prepared from experimental group 1, control group 1, experimental group 2, control group 2, experimental group 3, control group 3, and glucose syrup, respectively.

The experimental groups 1, 2 and 3 are syrups prepared by the methods of the examples 1, 2 and 3, the control group 1 is a product prepared by the complex enzyme 1 only comprising cellulase and pectinase and the complex enzyme 2 only comprising β -amylase and amyloglucosidase in the process of preparing the syrup according to the example 1, the control group 2 is a product prepared by the complex enzyme 1 only comprising cellulase and hemicellulase and the complex enzyme 2 only comprising β -amylase and pullulanase in the process of preparing the syrup according to the example 2, the control group 3 is a product prepared by the complex enzyme 1 only comprising cellulase, pectinase and α -galactosidase and the complex enzyme 2 only comprising amyloglucosidase and pullulanase in the process of preparing the syrup according to the example 3, and the glucose syrup is a product prepared according to the patent application number 2017110430300.

TABLE 1 sensory test results

As can be seen from table 1, the experimental group of product syrup prepared according to the 3 examples of the present application is of higher quality, comparable or even better in sweetness, color, smell and condition to the prior art glucose syrup. Meanwhile, comparing the experimental group 1 with the control group 1, the experimental group 2 with the control group 2, and the experimental group 3 with the control group 3 respectively, it can be known that the quality effect of the prepared syrup is reduced when a certain enzyme in the complex enzyme 1 composition and a certain enzyme in the complex enzyme 2 composition are lacked, so that the enzyme compositions of the complex enzyme 1 and the complex enzyme 2 in the application are mutually synergistic to improve the quality of the prepared syrup.

(II) DE value and relative molecular mass measurement

DE values and relative molecular masses

As can be seen from Table 2, the DE values of the syrups prepared according to the 3 examples of the present application, the relative molecular masses of the syrups are comparable to or even better than those of the glucose syrups prepared according to the prior art, the relative molecular masses of the syrups being less than or equal to 1000 Da. Meanwhile, comparing the experimental group 1 and the control group 1, the experimental group 2 and the control group 2, and the experimental group 3 and the control group 3 respectively, it can be known that the DE value of the prepared syrup is reduced and the relative molecular mass is slightly larger when a certain enzyme in the complex enzyme 1 composition and a certain enzyme in the complex enzyme 2 composition are absent. Therefore, the components of the complex enzyme 1 and the complex enzyme 2 in the application are mutually synergistic, so that the prepared syrup has small relative molecular mass, high enzymolysis degree and easy digestion and absorption.

(III) Oxidation resistance test

TABLE 3 Oxidation resistance test results

As can be seen from Table 3, the syrup prepared in the example 3 of the present application has a DPPH radical scavenging rate and hydroxyl radical scavenging rate far higher than those of glucose syrup prepared in the prior art, and the syrup prepared in the present application has a strong antioxidant capacity and a better antioxidant capacity than glucose syrup prepared in the prior art (which may have autoxidation). Has strong oxidation resistance, can reduce the oxidative stress reaction of animal organisms, improve the immunity of the animal organisms, improve the feed intake, increase the feed conversion rate, and further improve the growth rate of the animals. Meanwhile, comparing the experimental group 1 with the control group 1, the experimental group 2 with the control group 2, and the experimental group 3 with the control group 3 respectively, it can be seen that when a certain enzyme in the complex enzyme 1 composition and a certain enzyme in the complex enzyme 2 composition are lacked, the DPPH radical clearance and the hydroxyl radical clearance of the prepared syrup are reduced to some extent, and it can be seen that the mutual synergistic effect between the enzyme compositions of the complex enzyme 1 and the complex enzyme 2 in the application can obtain better effect.

(IV) residue test

TABLE 4 residue test results

Group of	Experimental group 1	Experimental group 2	Experimental group 3
				Crude protein	82.5％	59.7％	74.2％
Fat	7.13％	30.2％	13.9％

As can be seen from Table 4, the residue produced in the process of preparing syrup according to the 3 examples of the present application is rich in protein and fat, the total content of protein and fat is nearly 90%, the residue has high quality, and the residue can be used for preparing protein powder, oil products, feed additives with high protein content, etc., and has great economic value.

(V) animal Experimental testing

1. Grouping of Experimental materials

Treatment group 1: the composition of the basic ration is shown in Table 5.1

Treatment group 2: the product prepared in example 1 was used in place of the glucose and sucrose component treatment group 3 in the basal diet group in equal amounts: table 5.1 table of composition of basic ration in which glucose syrup is substituted for glucose and sucrose in the group of basic ration in equal amount

2. Grouping of laboratory animals

144 healthy weaned piglets (about 8.6 kg/head) of consistent age in days were selected and randomly divided into 3 animal groups, each with 48 piglets, each with 4 replicate animal groups, each with 12 piglets.

3. Feeding management

The test pigsty daily management during the test was performed according to the normal program of the pigsty. Adopts a feeding method of free food intake and free water drinking. Keep the pigsty clean and sanitary and has good ventilation condition. The disease, death, etc. of piglets were observed and recorded regularly every day during the test period.

4. Experimental mode and experimental characterization

The feeding time intervals of 3 animal groups are the same, the daily ration feeding amount is the same, and the feeding period is 21 days.

The animals to be tested were tested and the experimental data were recorded, and the weight of piglets in each animal group was recorded before the start of the experiment as the initial weight of piglets. The weight of each animal group piglet was recorded as the end weight of the piglet after 21 days feeding experiment. The tests included growth performance, diarrhea rate and appearance scores. Wherein the growth performance comprises average daily feed intake, average daily gain, feed conversion ratio and death and culling rate. The calculation method is as follows:

average daily feed intake (total feed added-trough remainder)/(remaining pig head number in column × total days of the test + pig head number of dead panning × test days);

average daily gain (end of column weight-initial column weight + end of dead panned pigs weight)/(remaining number of heads in column × total days of trial + number of heads of dead panned pigs × days of trial);

the feed-meat ratio is equal to the average daily feed intake/average daily weight gain;

the mortality rate is (death elimination number × 100%)/total number of piglets in each group;

rate of diarrhea (total first diarrhea × 100%/(total number of trials × total days);

appearance scoring: the piglets are observed and compared once a week and can be divided into 4 grades of poor, medium, good and excellent according to the hair and the color of the piglets (the grades are respectively 1, 2, 3 and 4);

5. results of the experiment

TABLE 5.2 piglet experimental results

The experimental data were collated using Excel 2010, single factor analysis of variance using SPSS16.0 software, and significance of differences tested using Dun-can method, with results expressed as mean ± standard error.

As can be seen from table 5.2, the average end weight, average feed intake and average daily gain of piglets in the treatment group 2 were significantly higher than those in the treatment group 1 and the treatment group 3 among the 3 different daily ration treatment groups; the feed-meat ratio of the piglets of the treatment group 2 is superior to that of the piglets of the treatment group 1 and the treatment group 3 in the aspect of feed-meat ratio; from the aspect of diarrhea rate, the diarrhea rate of the piglets of the treatment group 2 is lowest; the appearance of the fur color of the piglets of each treatment group was not significantly different.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A method for preparing syrup by enzymolysis of starch raw materials is characterized by comprising the following steps:

liquefying, namely adjusting the pH of the enzymolysis liquid in the step (1) to 5.5-6.5, raising the temperature to 85-99 ℃, adding α -amylase, and stirring for 20-90 min to obtain a liquefied liquid;

and (3): separation: adjusting the pH of the liquefied liquid in the step (2) to 4.0-5.0, and performing centrifugal separation to obtain a precipitate and a supernatant; washing and centrifuging, washing the precipitate for 1-2 times by using water, centrifuging to obtain residues and washing liquid, and combining the washing liquid for next size mixing; drying and remoistening the residue to obtain a product containing protein and fat;

2. The method of preparing a syrup from an enzymatically hydrolyzed starch feedstock according to claim 1, wherein said starch feedstock is at least one of pea flour, corn flour, wheat flour, black bean flour, yam flour, potato flour, pumpkin flour, millet flour, sweet potato flour, tapioca flour, sweet potato flour, lotus root starch, potato flour starch products.

3. The method for preparing the syrup by using the enzymolysis starch raw material according to claim 1, wherein the addition amount of α -amylase in the step (2) is 10-30U/g.

4. The method for preparing syrup by enzymolysis of starch raw material according to claim 1, wherein iodine in the liquefied solution in the step (2) reacts to form a brownish red color, and DE value is 15% -20%.

5. The method for preparing the syrup by the enzymolysis of the starch raw material according to claim 1, wherein the rotation speed of centrifugal separation in the step (3) is 1500-3000 r/min, and the centrifugal time is 2-10 min.

6. The method for preparing syrup by enzymolysis of starch raw materials according to claim 1, wherein the complex enzyme 2 in the step (4) is β -amylase, pullulanase and amyloglucosidase, and the addition amounts are 200-400U/g, 0.1-0.5 ASPU/g and 50-300U/g, respectively.

7. The method for preparing the syrup by the enzymolysis of the starch raw material according to claim 1, wherein the centrifugal rotation speed in the step (5) is 1500-3000 r/min, and the centrifugal time is 2-10 min.

8. The method for preparing syrup by enzymolysis of starch raw material according to claim 1, wherein the light transmittance of the ion exchange solution in the step (6) is not less than 95%.

9. The method for preparing syrup by enzymolysis of starch raw material according to claim 1, wherein the temperature of vacuum concentration in step (7) is 60-65 ℃ and the pressure is 0.075-0.085 MPa.

10. A syrup produced by the method of any one of claims 1 to 9.