A method for starch classification

Abstract

The present invention relates to the technical field of starch classification, and in particular to a method for classifying starch. Specifically, when classifying starch, a specific dispersant is selected, and starch with different particle sizes in the selected dispersant has different dispersion speeds in the dispersant. Furthermore, when the concentration of the dispersant is different, the starch presents a more obvious difference in sedimentation speed in the dispersant, and accordingly, the starch is successfully classified.

Description

Technical Field

[0001] The invention relates to the technical field of starch grading, and in particular to a method for grading starch. Background Art

[0002] Starch is a carbohydrate extracted from plants. In daily diet, it is the main energy provider and source for the body. In addition, starch has a wide range of application value in the fields of cosmetics, papermaking, food and chemical industry. The functional properties of starch are usually closely related to its structure; different functional values ​​can be given to starch through different modification methods. The size of starch granules is an important part of starch structure; some large starch granules have a tight structure, which makes their modification and processing difficult, which is not conducive to the application in industrial fields such as chemical industry; and large starch granules are slower than small starch granules in the process of dietary digestion due to their smaller specific surface area and large swelling degree, which can slow down the increase of blood sugar index in the body and is more conducive to the development of starch-based healthy foods. Therefore, by separating starch granules of different sizes, different functional values ​​can be exerted in different application fields, such as cosmetics, papermaking, food and chemical industry.

[0003] Traditional methods for separating starch particles, such as static sedimentation and sieving, take a long time, have poor precision and repeatability, and have certain limitations. Among them, the sieving method is to use sieves of different mesh sizes to sieve starch particles to separate starch particles of the same particle size. This method is simple to operate, but has poor repeatability and precision and is time-consuming; the static sedimentation method is a method that utilizes the volume difference of starch particles in aqueous solution. During the static process, starch particles of different sizes have different sedimentation rates, thereby separating starch particles of different sizes. The repeatability of this method is slightly better than the sieving method, but the preparation process takes a long time, which is not conducive to the application of actual industrial production. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a starch classification method, in which a suitable dispersant is selected, starch particles of different sizes can be classified under specific conditions, and the operation is simple and repeatable.

[0005] The technical solution adopted by the present invention is:

[0006] A method for starch classification comprises the following steps:

[0007] 1) preparing high and low concentration dispersants, adding starch to the high concentration dispersant to prepare a suspension (concentration 2-10%), centrifuging (centrifugal speed of 800 rpm-1000 rpm, centrifugal time of at least 5 min) and collecting the precipitate and the supernatant respectively;

[0008] 2) adding a high concentration of dispersant to the precipitated sample in step 1), centrifuging (at a centrifugal speed of 800 rpm-1000 rpm and a centrifugal time of at least 5 min), collecting the precipitate and the supernatant respectively, repeating the operation until there is no precipitate, and finally combining the precipitates to obtain a large-granular starch precipitate;

[0009] 3) combining the upper liquids in steps 1) and 2), centrifuging (at a centrifugal speed of 4500 rpm-5000 rpm for at least 10 min), and collecting the precipitate and the upper liquid respectively;

[0010] 4) adding a low concentration dispersant to the precipitated sample of step 3) to obtain a suspension, centrifuging (the centrifugal speed is 500 rpm-1000 rpm, and the centrifugal time is at least 10 min) to collect the precipitate and the supernatant respectively, repeating the operation until there is no precipitate, and finally combining the precipitates to obtain a medium granular starch precipitate;

[0011] 5) combining the upper liquids obtained in step 3) and 4), centrifuging (at a centrifugal speed of 4500-5000 rpm for at least 5 min) to collect the precipitate as small granular starch precipitate;

[0012] 6) The collected large-granule starch precipitate, medium-granule starch precipitate and small-granule starch precipitate are washed and dried (temperature 40° C., time 24 h) to obtain large, medium and small-granule starch, respectively.

[0013] The dispersant is a glycerol-water solution or a carbon tetrachloride-ethanol solution.

[0014] When the average particle size of the starch granules is relatively large (30-60 μm, excluding 30 μm), the concentration of the high-concentration dispersant is 85-95%, and the concentration of the low-concentration dispersant is 70-80%.

[0015] When the average particle size of the starch particles is relatively small (10-30 μm), the concentration of the high-concentration dispersant is 70-80%, and the concentration of the low-concentration dispersant is 50-60%.

[0016] The drying temperature in step 6) is 40° C. and the drying time is 24 hours.

[0017] The starch is starch from different plant sources, such as corn starch, wheat starch, tapioca starch, potato starch, sweet potato starch, pea starch, mung bean starch, jackfruit seed starch, etc.

[0018] In the traditional separation of starch, there is a water separation method. The sedimentation rate of starch in water is relatively fast, so the difference in the sedimentation rate of starch with small diameter difference in water is not very obvious, so it is impossible to directly perform very effective separation. In the present invention, the inventors selected a specific dispersant, and the dispersion rate of starch with different particle sizes in the selected dispersant is different. Furthermore, when the concentration of the dispersant is different, the starch shows a more obvious difference in sedimentation rate in the dispersant, which lays the foundation for the classification of starch.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are:

[0020] The present invention adopts glycerol-water solution or carbon tetrachloride-ethanol solution as a dispersant. Dispersants of different concentrations have different adhesion effects on starches of different particle sizes, which leads to a larger difference in the sedimentation speed of starches of different sizes in the dispersant. The starch is first dispersed in a high-concentration dispersant, and large-particle starch particles are first precipitated and centrifuged out. Then, the starch is dispersed in a low-concentration dispersant, and medium-particle starch particles are precipitated and centrifuged out. Finally, small-particle starch particles are centrifuged out, and the classification is completed. The classification method of the present invention can quickly and effectively classify and prepare starch particles of different sizes, the method has good repeatability, high classification efficiency, and can be applied to production on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Microscope images of potato starch before and after classification in Example 1.

[0022] Figure 2 Microscope pictures of corn starch before and after classification in Example 2.

[0023] Figure 3 Microscope images of wheat starch before and after classification in Example 3.

[0024] Figure 4 Be the microscope picture of pea starch before and after embodiment 4 classification.

[0025] Figure 5 Microscope images of potato starch before and after classification in Example 5.

[0026] Figure 6 Microscope images of potato starch before and after classification in Example 6.

[0027] Figure 7 Microscope images of potato starch before and after classification in Example 7. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention are described below in conjunction with examples. However, the following examples are only used to illustrate the present invention in detail and are not intended to limit the scope of the present invention in any way.

[0029] Embodiment 1:

[0030] A method for potato starch classification comprises the following steps:

[0031] (1) Take 1 g of potato starch (average particle size 33.43 μm) and prepare 75% or 90% carbon tetrachloride-ethanol solution for later use.

[0032] (2) A 90% carbon tetrachloride-ethanol solution was selected as a dispersant and mixed with a potato starch sample to prepare a 2.5% (w / v) starch suspension. The suspension was centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected separately.

[0033] (3) The precipitate sample obtained in (2) was evenly dispersed with 40 mL of 90% carbon tetrachloride-ethanol solution and centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected respectively; the precipitate sample was repeatedly treated 10 times, and finally the precipitate and the supernatant were collected respectively. The obtained precipitate was dried to obtain 0.77 g of large-particle potato starch.

[0034] (4) Combine and collect the supernatant liquids from steps (2)-(3), centrifuge at 4500 rpm for 10 min, and collect the precipitate and supernatant liquid.

[0035] (5) 40 mL of 75% carbon tetrachloride-ethanol solution was added to the precipitate from (4) to obtain a suspension, which was then centrifuged at 800 rpm for 10 min. The precipitate and the supernatant were collected and the treatment was repeated 13 times. Finally, the precipitate was collected and dried to obtain 0.12 g of medium-granular potato starch.

[0036] (6) The upper layers of the liquids from steps (4) and (5) were combined and collected, and the mixture was centrifuged at 5000 rpm for 10 min. The precipitate was collected and dried to obtain 0.11 g of small-particle potato starch.

[0037] (7) The large, medium and small particle potato starch obtained in the above step were washed with ethanol for 3 times, the ethanol solution was removed, the mixture was collected and placed in an oven for drying for 24 h, and passed through a 100 mesh sieve to finally obtain 0.77 g of dry and classified large particle potato starch, 0.12 g of medium particle potato starch, and 0.11 g of small particle potato starch.

[0038] The results showed that the average particle size of large-particle potato starch was 41.55 μm, the average particle size of medium-particle potato starch was 24.45 μm, and the average particle size of small-particle potato starch was 19.88 μm.

[0039] Microscopic images of large-particle potato starch, medium-particle potato starch, and small-particle potato starch Figure 1 As shown. A1 is unfractionated potato starch, A2 is small-particle potato starch, A3 is medium-particle potato starch, and A4 is large-particle potato starch. Figure 1 It can be seen that large, medium and small starch particles are clearly distinguished in size, medium starch particles are between large and small particles, large, medium and small particles are less mixed with each other, and the separation effect is obvious.

[0040] Example 2

[0041] A method for corn starch classification comprises the following steps:

[0042] (1) Take 1 g of corn starch (average particle size 15.43 μm) and prepare 55% or 75% glycerol-water solution for later use.

[0043] (2) A 75% glycerol-water solution was selected as a dispersant and prepared with a corn starch sample to form a 2.5% (w / v) starch suspension. The suspension was centrifuged at 800 rpm for 5 min, and the precipitate and the supernatant were collected separately.

[0044] (3) The precipitate sample obtained in (2) was evenly dispersed with 40 mL of 75% glycerol-water solution and centrifuged at 800 rpm for 5 min, and the precipitate and the supernatant were collected respectively; the precipitate sample was repeatedly treated 10 times, and finally the precipitate and the supernatant were collected respectively. The obtained precipitate was dried to obtain 0.72 g of large-grain corn starch precipitate.

[0045] (4) Combine and collect the supernatant liquids from the above steps (2)-(3), centrifuge at 4500 rpm for 10 min, and collect the precipitate and supernatant liquid.

[0046] (5) 40 mL of 55% glycerol-water solution was added to the precipitate from (4) above to disperse evenly to obtain a suspension, which was then centrifuged at 700 rpm for 5 min. The precipitate and the supernatant were collected separately. The precipitate sample was treated repeatedly 11 times, and finally the precipitate was collected and dried to obtain 0.17 g of medium-granular corn starch precipitate.

[0047] (6) The upper layers of the liquids from steps (4) and (5) were combined, and the mixture was centrifuged at 5000 rpm for 10 min. The precipitate was collected and dried to obtain 0.11 g of small-particle corn starch precipitate.

[0048] (7) The large, medium and small particle corn starch precipitates obtained in the above steps were washed with ethanol three times, the ethanol solution was removed, the precipitates were collected and placed in an oven to dry for 24 hours, and passed through a 100 mesh sieve to finally obtain 0.72 g of dry and classified large particle corn starch, 0.17 g of medium particle corn starch, and 0.11 g of small particle corn starch.

[0049] The results showed that the average particle size of large-grain corn starch was 17.13 μm, the average particle size of medium-grain corn starch was 13.98 μm, and the average particle size of small-grain corn starch was 11.88 μm.

[0050] Microscope images of large-grain corn starch, medium-grain corn starch, and small-grain corn starch Figure 2 As shown. Figure B1 is unclassified corn starch, Figure B2 is small-particle corn starch, Figure B3 is medium-particle corn starch, and Figure B4 is large-particle corn starch. Figure 2 It can be seen that although the size of corn starch particles is small, large, medium and small starch particles can still be effectively separated, and the separation effect is ideal.

[0051] Example 3

[0052] A method for wheat starch classification comprises the following steps:

[0053] (1) Take 1 g of wheat starch (average particle size 15.25 μm) and prepare 55% or 75% glycerol-water solution for later use.

[0054] (2) A 75% glycerol-water solution was selected as a dispersant and prepared with a wheat starch sample into a 2.5% (w / v) starch suspension. The suspension was centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected separately.

[0055] (3) The precipitate sample obtained in (2) was evenly dispersed with 40 mL of 75% glycerol-water solution and centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected respectively; the precipitate sample was repeatedly treated 10 times, and finally the precipitate and the supernatant were collected respectively. The obtained precipitate was dried to obtain 0.77 g of large-particle wheat starch.

[0056] (4) Combine and collect the supernatant liquids from the above steps (2)-(3), centrifuge at 4500 rpm for 10 min, and collect the precipitate and supernatant liquid.

[0057] (5) 40 mL of 55% glycerol-water solution was added to the precipitate from (4) to obtain a suspension, which was then evenly dispersed and centrifuged at 1000 rpm for 5 min. The precipitate and the supernatant were collected respectively. The precipitate sample was treated repeatedly 11 times, and finally the precipitate was collected and dried to obtain 0.09 g of medium-granular wheat starch.

[0058] (6) The upper layers of step (4) and (5) were combined, centrifuged at 5000 rpm for 10 min, and the precipitate was collected and dried to obtain 0.14 g of small-particle wheat starch.

[0059] (7) The large, medium and small granule wheat starch obtained in the above step were washed with ethanol three times, the ethanol solution was removed, the starch was collected and placed in an oven to dry for 24 h, and passed through a 100 mesh sieve to finally obtain 0.77 g of dry and graded large granule wheat starch, 0.09 g of medium granule wheat starch, and 0.14 g of small granule wheat starch.

[0060] The results showed that the average particle size of large-particle wheat starch was 18.12 μm, the average particle size of medium-particle wheat starch was 12.86 μm, and the average particle size of small-particle wheat starch was 8.33 μm.

[0061] Microscopic images of large-grain wheat starch, medium-grain wheat starch, and small-grain wheat starch Figure 3 As shown. Figure C1 is unfractionated wheat starch, Figure C2 is small-particle wheat starch, Figure C3 is medium-particle wheat starch, and Figure C4 is large-particle wheat starch. Figure 3 It can be seen that the large, medium and small granule starch in wheat starch are well separated.

[0062] Example 4

[0063] A method for grading pea starch comprises the following steps:

[0064] (1) Take 1 g of pea starch (average particle size 15.83 μm) and prepare 55% or 75% glycerol-water solution for standby use.

[0065] (2) A 75% glycerol-water solution was selected as a dispersant and prepared into a 2.5% (w / v) starch suspension with a pea starch sample. The suspension was centrifuged at 800 rpm for 5 min, and the precipitate and the supernatant were collected respectively.

[0066] (3) The precipitate sample obtained in (2) was evenly dispersed with 40 mL of 75% glycerol-water solution and centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected respectively; the precipitate sample was repeatedly treated 10 times, and finally the precipitate and the supernatant were collected respectively. The obtained precipitate was dried to obtain 0.80 g of large-particle pea starch.

[0067] (4) Combine and collect the supernatant liquids from the above steps (2)-(3), centrifuge at 4500 rpm for 10 min, and collect the precipitate and supernatant liquid.

[0068] (5) 40 mL of 55% glycerol-water solution was added to the precipitate from (4) to obtain a suspension, which was then evenly dispersed and centrifuged at 1000 rpm for 5 min. The precipitate and the supernatant were collected respectively. The precipitate sample was treated repeatedly 11 times, and finally the precipitate was collected and dried to obtain 0.11 g of medium-granular pea starch.

[0069] (6) The upper layers of the liquids from steps (4) and (5) were combined, and the mixture was centrifuged at 5000 rpm for 10 min. The precipitate was collected and dried to obtain 0.09 g of small-particle pea starch.

[0070] (7) The large, medium and small particle pea starch obtained in the above step were washed with ethanol for 3 times, the ethanol solution was removed, the starch was collected and placed in an oven to dry for 24 h, and passed through a 100 mesh sieve to finally obtain 0.80 g of dry and classified large particle pea starch, 0.11 g of medium particle pea starch, and 0.09 g of small particle pea starch.

[0071] The results showed that the average particle size of large-particle pea starch was 17.33 μm, the average particle size of medium-particle pea starch was 14.34 μm, and the average particle size of small-particle pea starch was 11.49 μm.

[0072] Microscopic images of large-grain pea starch, medium-grain pea starch, and small-grain pea starch Figure 4 As shown. Figure D1 is unclassified pea starch, Figure D2 is small-particle pea starch, Figure D3 is medium-particle pea starch, and Figure D4 is large-particle pea starch. Figure 4 It can be seen that the large, medium and small particles of pea starch have been basically effectively separated, and only a small part of the small and medium particles have not been separated.

[0073] Example 5

[0074] A method for potato starch classification comprises the following steps:

[0075] (1) Take 1 g of potato starch (average particle size 33.43 μm) and prepare 80% carbon tetrachloride-ethanol solution for later use.

[0076] (2) 80% carbon tetrachloride-ethanol solution was selected as a dispersant and prepared with a potato starch sample into a 2.5% (w / v) starch suspension. The suspension was centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected separately.

[0077] (3) The precipitate sample obtained in (2) was evenly dispersed with 40 mL of 80% carbon tetrachloride-ethanol solution and centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected respectively; the precipitate sample was repeatedly treated 10 times, and finally the precipitate and the supernatant were collected respectively. The obtained precipitate was dried to obtain 0.80 g of large-particle potato starch.

[0078] (4) Combine and collect the supernatant liquids from steps (2)-(3), centrifuge at 4500 rpm for 10 min, and collect the precipitate and supernatant liquid.

[0079] (5) 40 mL of 80% carbon tetrachloride-ethanol solution was added to the precipitate from (4) to obtain a suspension, which was then centrifuged at 800 rpm for 10 min. The precipitate and the supernatant were collected and the treatment was repeated 13 times. Finally, the precipitate was collected and dried to obtain 0.05 g of medium-granular potato starch.

[0080] (6) The upper layers of the liquids from steps (4) and (5) were combined and collected, and the mixture was centrifuged at 5000 rpm for 10 min. The precipitate was collected and dried to obtain 0.15 g of small-particle potato starch.

[0081] (7) The large, medium and small particle potato starch obtained in the above step were washed with ethanol for 3 times, the ethanol solution was removed, the mixture was collected and placed in an oven to dry for 24 h, and passed through a 100 mesh sieve to finally obtain 0.80 g of dry and classified large particle potato starch, 0.05 g of medium particle potato starch, and 0.15 g of small particle potato starch.

[0082] The results showed that the average particle size of large-particle potato starch was 39.43 μm, the average particle size of medium-particle potato starch was 30.37 μm, and the average particle size of small-particle potato starch was 21.89 μm.

[0083] Microscopic images of large-particle potato starch, medium-particle potato starch, and small-particle potato starch Figure 5 As shown. E1 is unfractionated potato starch, E2 is small-particle potato starch, E3 is medium-particle potato starch, and E4 is large-particle potato starch. Figure 1 It can be seen that the small-granule starch separated by this method is mixed with medium-granule starch, and the numerical value also reflects that the amount of medium-granule starch is small and the amount of small-granule starch is large.

[0084] Example 6

[0085] A method for potato starch classification comprises the following steps:

[0086] (1) Take 1 g of potato starch (average particle size 33.43 μm) and prepare 60% or 80% carbon tetrachloride-ethanol solution for later use.

[0087] (2) 80% carbon tetrachloride-ethanol solution was selected as a dispersant and prepared with a potato starch sample into a 2.5% (w / v) starch suspension. The suspension was centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected separately.

[0088] (3) The precipitate sample obtained in (2) was evenly dispersed with 40 mL of 80% carbon tetrachloride-ethanol solution and centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected respectively; the precipitate sample was repeatedly treated 10 times, and finally the precipitate and the supernatant were collected respectively. The obtained precipitate was dried to obtain 0.79 g of large-particle potato starch.

[0089] (4) Combine and collect the supernatant liquids from steps (2)-(3), centrifuge at 4500 rpm for 10 min, and collect the precipitate and supernatant liquid.

[0090] (5) 40 mL of 60% carbon tetrachloride-ethanol solution was added to the precipitate from (4) to obtain a suspension, which was then centrifuged at 800 rpm for 10 min. The precipitate and the supernatant were collected and the treatment was repeated 13 times. Finally, the precipitate was collected and dried to obtain 0.12 g of medium-granular potato starch.

[0091] (6) The upper layers of the liquids from steps (4) and (5) were combined and collected, and the mixture was centrifuged at 5000 rpm for 10 min. The precipitate was collected and dried to obtain 0.09 g of small-particle potato starch.

[0092] (7) The large, medium and small particle potato starch obtained in the above step were washed with ethanol for 3 times, the ethanol solution was removed, the mixture was collected and placed in an oven for drying for 24 h, and passed through a 100 mesh sieve to finally obtain 0.79 g of dry and classified large particle potato starch, 0.12 g of medium particle potato starch, and 0.09 g of small particle potato starch.

[0093] The results showed that the average particle size of large-particle potato starch was 39.46 μm, the average particle size of medium-particle potato starch was 22.65 μm, and the average particle size of small-particle potato starch was 16.87 μm.

[0094] Microscopic images of large-particle potato starch, medium-particle potato starch, and small-particle potato starch Figure 6 As shown. F1 is unclassified potato starch, F2 is small-particle potato starch, F3 is medium-particle potato starch, and F4 is large-particle potato starch. Figure 1 It can be seen that the large-granule starch separated by this method is mixed with medium-granule starch, and the medium-granule starch is mixed with small-granule starch. The numerical value also reflects that the amount of small-granule starch is small, and the amount of large-granule starch is large.

[0095] Example 7

[0096] A method for potato starch classification comprises the following steps:

[0097] (1) Take 1 g of potato starch (average particle size 33.43 μm) and prepare 75% or 90% propylene glycol-water solutions for later use.

[0098] (2) A 90% propylene glycol-water solution was selected as a dispersant and prepared with a potato starch sample into a 2.5% (w / v) starch suspension. The suspension was centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected separately.

[0099] (3) The precipitate sample obtained in (2) was evenly dispersed with 40 mL of 90% propylene glycol-water solution and centrifuged at 1000 rpm for 5 min, and the precipitate and the supernatant were collected respectively; the precipitate sample was repeatedly treated 10 times, and finally the precipitate and the supernatant were collected respectively. The obtained precipitate was dried to obtain 0.95 g of large-particle potato starch.

[0100] (4) Combine and collect the supernatant liquids from steps (2)-(3), centrifuge at 4500 rpm for 10 min, and collect the precipitate and supernatant liquid.

[0101] (5) 40 mL of 75% propylene glycol-water solution was added to the precipitate from (4) to obtain a suspension, which was then centrifuged at 800 rpm for 10 min. The precipitate and the supernatant were collected and the treatment was repeated 13 times. Finally, the precipitate was collected and dried to obtain 0.03 g of medium-granular potato starch.

[0102] (6) The upper layers of the liquids from steps (4) and (5) were combined and collected, and the mixture was centrifuged at 5000 rpm for 10 min. The precipitate was collected and dried to obtain 0.02 g of small-particle potato starch.

[0103] (7) The large, medium and small particle potato starch obtained in the above step were washed with ethanol for 3 times, the ethanol solution was removed, the mixture was collected and placed in an oven for drying for 24 h, and passed through a 100 mesh sieve to finally obtain 0.95 g of dry and classified large particle potato starch, 0.03 g of medium particle potato starch, and 0.02 g of small particle potato starch.

[0104] The results showed that the average particle size of large-particle potato starch was 35.79 μm, the average particle size of medium-particle potato starch was 30.93 μm, and the average particle size of small-particle potato starch was 23.04 μm.

[0105] Microscopic images of large-particle potato starch, medium-particle potato starch, and small-particle potato starch Figure 7 As shown. G1 is unfractionated potato starch, G2 is small-particle potato starch, G3 is medium-particle potato starch, and G4 is large-particle potato starch. Figure 1It can be seen that the large, medium and small particles separated by this method are not uniform in size and have no obvious size difference. In addition, the proportion of small and medium particles separated is very small, and the particle sizes obtained are also relatively close, which fails to achieve the purpose of separation.

[0106] From the above examples, it can be seen that when the selected dispersant concentration meets the requirements, the method of the present invention can effectively separate large, medium and small granule starches. However, when only a single concentration of dispersant is used, it is shown that small granule starch is mixed with medium granule starch, and the separation effect is not good. When the high and low concentrations of the dispersant are not appropriately selected, the phenomenon of small granule starch being mixed with medium granule starch occurs, and the separation is not ideal. When the type of dispersant is not appropriately selected, the purpose of starch classification cannot be achieved.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for starch classification, characterized in that: The following steps are involved: 1) preparing high-concentration and low-concentration dispersants, adding starch to the high-concentration dispersant to prepare a suspension, and collecting the precipitate and the upper layer liquid respectively after centrifugation at 800rpm-1000rpm; the dispersant is a carbon tetrachloride-ethanol solution; when the average particle size of the starch particles is 30-60μm, the concentration of the high-concentration dispersant is 85-95%, and the concentration of the low-concentration dispersant is 70-80%; when the average particle size of the starch particles is 10-30μm, the concentration of the high-concentration dispersant is 70-80%, and the concentration of the low-concentration dispersant is 50-60%; 2) adding a high concentration of dispersant to the precipitated sample in step 1), centrifuging at 800 rpm-1000 rpm, collecting the precipitate and the supernatant, repeating the operation until there is no precipitate, and finally combining the precipitates to obtain a large-granular starch precipitate; 3) combining the upper liquids in steps 1) and 2), centrifuging at 4500 rpm-5000 rpm, and collecting the precipitate and the upper liquid respectively; 4) adding a low concentration dispersant to the precipitated sample of step 3) to obtain a suspension, centrifuging at 500 rpm-1000 rpm to collect the precipitate and the supernatant respectively, repeating the operation until there is no precipitate, and finally combining the precipitates to obtain a medium granular starch precipitate; 5) combining the upper liquids obtained in step 3) and 4), and centrifuging at 4500-5000 rpm to collect the precipitate to obtain small granular starch precipitate; 6) The collected large-granule starch precipitate, medium-granule starch precipitate and small-granule starch precipitate are washed and dried to obtain large-, medium- and small-granule starch respectively.

2. The classification method according to claim 1, characterized in that: The drying temperature in step 6) is 40° C. and the drying time is 24 hours.

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