阅读说明：本技术 一种提取甘薯地上部淀粉的方法 (Method for extracting sweet potato overground part starch ) 是由 赵凌霄 曹清河 戴习彬 邓逸烔 周志林 赵冬兰 张安 于 2019-10-29 设计创作，主要内容包括：本发明公开了一种提取甘薯地上部淀粉的方法。所述方法包括取样、研磨、过滤、离心、去除杂质及收集淀粉等步骤,以新鲜的甘薯叶片、叶柄或茎秆,或者新鲜的甘薯叶片、叶柄或茎秆采摘后立即冷冻保存的样品作为提取材料,以0.1％的NaOH溶液作为提取介质,依次采用100目和200目的尼龙纱网布进行过滤；控制离心转速为6000g,并且每次离心去除上清后均刮除杂质,清洗后烘干收集淀粉。本发明操作简单、快速且节约成本,提取效率高,成本低,获得的淀粉纯度高,且不会被损害,适合于甘薯的叶片、叶柄及茎秆淀粉的提取,有利于充分地利用甘薯地上部的淀粉资源。(The invention discloses a method for extracting sweet potato overground part starch. The method comprises the steps of sampling, grinding, filtering, centrifuging, removing impurities, collecting starch and the like, wherein fresh sweet potato leaves, petioles or stalks or samples which are immediately frozen and preserved after the fresh sweet potato leaves, petioles or stalks are picked are used as extraction materials, 0.1% NaOH solution is used as an extraction medium, and nylon gauze fabrics of 100 meshes and 200 meshes are sequentially adopted for filtering; controlling the centrifugal rotation speed to be 6000g, removing impurities after centrifuging each time, cleaning, drying and collecting starch. The method has the advantages of simple and rapid operation, cost saving, high extraction efficiency and low cost, and the obtained starch has high purity and can not be damaged, thereby being suitable for extracting the starch of the leaves, petioles and stalks of the sweet potatoes and being beneficial to fully utilizing the starch resources on the overground part of the sweet potatoes.)

1. The method for extracting the starch of the overground part of the sweet potato is characterized by comprising the following specific steps of:

(1) sampling: taking fresh sweet potato leaves, petioles or stalks, or samples which are immediately frozen and preserved after the fresh sweet potato leaves, petioles or stalks are picked as extraction raw materials;

(2) grinding: placing the extracted raw materials in a grinding cup of a household mixer, adding 0.1% NaOH solution, grinding for 5-10 times intermittently, grinding for 2-5 min in total, and ensuring that a sample is fully ground and crushed to obtain slurry;

(3) and (3) filtering: firstly, selecting 100-mesh nylon gauze cloth to extrude and filter slurry; the residues are further put back into a grinding cup of a stirrer, 0.1% NaOH solution is added to grind for 2-3 min, and then a nylon gauze cloth with 100 meshes is used for filtering; finally, using 200-mesh nylon gauze to extrude and filter all the slurry and collecting the slurry to obtain coarse starch slurry;

(4) centrifuging and removing impurities: subpackaging the crude starch slurry, centrifuging at 6000g of rotating speed for 5-6 min, removing supernatant, and scraping dark green impurities on the surface layer of precipitate by using a medicine spoon; then 0.1% NaOH solution is used for cleaning, deep green impurities on the surface of the sediment are scraped after each centrifugation and pouring out of the supernatant, and the surface of the sediment is ensured to have no obvious impurities;

(5) collecting starch: suspending and cleaning the precipitate obtained in the step (4) by using excess distilled water, and removing residual NaOH in the precipitate; then, excessive absolute ethyl alcohol is used for cleaning the precipitate, and the precipitate is dried at 40 ℃ after being thoroughly dehydrated; and (4) passing the dried starch sample through a 100-mesh screen, and collecting the starch.

2. The method according to claim 1, wherein in the step (2), the volume ratio of the mass of the extraction raw material to the 0.1% NaOH solution is 4-5: 20-30, g: and (mL).

3. The method according to claim 1, wherein in the step (4), the 0.1% NaOH solution is washed 2-3 times.

4. The method according to claim 1, wherein in the step (5), the number of washing is 2-3.

Technical Field

The invention belongs to the technical field of starch extraction and processing, and relates to a method for extracting sweet potato overground part starch.

Background

Sweet potatoes (Ipomoea batatas (L.) Lam.) have the advantages of low investment, high yield, strong adaptability and the like. The sweet potato tuber is the main organ for storing nutrients, the overground part resources are quite rich, the yield is basically equivalent to that of the tuber, and the growth of the two has close relation. Researches show that during the growth process of sweet potatoes, starch synthesis is carried out on the root tuber of the underground part, and the leaves, petioles, stalks and other parts of the overground part. The photosynthetic product is mainly used for constructing the shape of the overground part plant in the early growth stage of the sweet potato, and dry matters are continuously transferred to the underground part under dark conditions or when the root tuber is expanded in the later stage. Thus, the overground starch belongs to a temporary starch, while the root starch belongs to a storage starch, and the synthesis and properties of the overground starch can influence the root starch. However, the above-ground part is different from the root tuber, the starch content is low, and the separation is difficult, so the characteristic research of the above-ground part starch of the sweet potato is still insufficient at the present stage. Meanwhile, in actual production, the overground part of the sweet potato is usually abandoned, so that not only can the environment be polluted, but also the resource is wasted. Therefore, the effective separation and extraction of the sweet potato overground part starch become a problem to be solved urgently.

At present, no report is found on the research on the method for extracting the stem and leaf starch of the sweet potato, and the existing methods for extracting the starch of other plant leaves all have certain problems, and the specific analysis is as follows: firstly, for the extraction of potato, corn and arabidopsis thaliana leaf starch, a conventional method is to mix propanesulfonic acid, EDTA and ethylene glycol in proportion to serve as an extracting solution (MOPS buffer solution), the method can better protect the starch, but the reagents have higher price and are complicated in preparation process, and the method is not beneficial to large-scale investment in production practice; in addition, the extracted starch contains more impurities and is low in purity, and subsequent experiments are easily influenced; secondly, the ultrasonic method can be used for purifying the starch of the tobacco leaves, but the ultrasonic process usually damages the surface of starch grains; thirdly, NaOH aqueous solution with lower pH (the pH is 8-12) can destroy the cell structure of the tobacco leaves to a certain extent to release starch, but when the method is applied to other plants such as sweet potatoes, the extraction efficiency is not high; fourthly, the cellulose content in the petiole and the stem of the sweet potato is higher, the sweet potato is difficult to be thoroughly ground, the cell structure is not fully damaged in the conventional method, and certain difficulty is brought to the extraction of starch. Therefore, improvement on the existing leaf starch extraction method is needed, and establishment of an extraction method aiming at the sweet potato above-ground starch is beneficial to more comprehensively researching the synthesis and characteristics of the sweet potato above-ground and below-ground starch.

Disclosure of Invention

In order to overcome the defects of the existing leaf starch extraction method, the invention provides the method for extracting the sweet potato overground part starch, the extraction efficiency and purity of the sweet potato overground part starch are higher, and the consumption cost is lower.

The technical scheme of the invention is as follows:

a method for extracting sweet potato overground part starch comprises the steps of sampling, grinding, filtering, centrifuging, removing impurities, collecting starch and the like, wherein a fresh sample is used as an extraction material, 0.1% NaOH solution (with the pH value of about 12.4) is used as an extraction medium, and nylon gauze cloth of 100 meshes and 200 meshes is selected for filtering; the centrifugal rotating speed is 6000g, impurities are scraped after the supernatant is removed by centrifugation each time, and the method comprises the following specific steps:

(1) sampling: taking fresh sweet potato leaves, petioles or stalks, or samples which are immediately frozen and preserved at (-20 ℃) after the fresh sweet potato leaves, petioles or stalks are picked as extraction raw materials;

(2) grinding: placing the extracted raw materials in a grinding cup of a household mixer, adding 0.1% NaOH solution, grinding for 5-10 times intermittently, grinding for 2-5 min in total, and ensuring that a sample is fully ground and crushed to obtain slurry;

(3) and (3) filtering: firstly, selecting 100-mesh nylon yarn mesh cloth (the average pore diameter is 150 mu m) to extrude and filter slurry; the residues are further put back into a grinding cup of a stirrer, 0.1% NaOH solution is added to grind for 2-3 min, and then a nylon gauze cloth with 100 meshes is used for filtering; finally, using 200-mesh nylon gauze cloth (with the average pore diameter of 75 mu m) to extrude and filter all the slurry and then collecting the slurry to obtain crude starch slurry;

(4) centrifuging and removing impurities: subpackaging the crude starch slurry, centrifuging at 6000g of rotating speed for 5-6 min, removing supernatant, and scraping dark green impurities on the surface layer of precipitate by using a medicine spoon; then 0.1% NaOH solution is used for cleaning, deep green impurities on the surface of the sediment are scraped after each centrifugation and pouring out of the supernatant, and the surface of the sediment is ensured to have no obvious impurities;

(5) collecting starch: suspending and cleaning the precipitate obtained in the step (4) by using excess distilled water, and removing residual NaOH in the precipitate; then, excessive absolute ethyl alcohol is used for cleaning the precipitate, and the precipitate is dried at 40 ℃ after being thoroughly dehydrated; and (4) passing the dried starch sample through a 100-mesh screen, and collecting the starch.

Preferably, in the step (2), the volume ratio of the mass of the extraction raw material to the 0.1% NaOH solution is 4-5: 20-30, g: and (mL).

Preferably, in the step (4), the number of times of washing with the 0.1% NaOH solution is 2-3.

Preferably, in the step (5), the number of times of cleaning is 2-3.

Compared with the existing leaf starch extraction method, the method has the following advantages:

(1) the overground part of the fresh sweet potato or a sample which is frozen and preserved immediately after picking is selected for extracting the starch, so that the loss of the starch caused by the heating process of a common extraction method is avoided, the recovery rate of the starch is improved, and the extraction time is saved;

(2) the starch extraction is carried out by using a low-concentration NaOH aqueous solution (the pH is about 12.4), so that the cell structure can be fully damaged to release the starch, and the starch structure is not damaged;

(3) the nylon gauze cloth is selected for filtering, so that the coarse starch slurry can be extruded, and the time is saved;

(4) the suspended coarse starch slurry is completely distributed into a plurality of centrifuge tubes for centrifugation, and starch can be collected in each centrifuge tube, so that the recovery efficiency of the starch is improved; in addition, the centrifugal rotating speed is set to be 6000g, the centrifugal time is 5-6 min, the starch and the impurities can be well separated, and the time is saved; after centrifugation, a medicine spoon is used for scraping impurities on the surface of the sediment, so that the purity of the collected starch is higher;

in conclusion, the extraction method of the sweet potato overground part starch has higher separation efficiency and purity, complete starch grains and undamaged surface.

Drawings

FIG. 1 is a drawing of an optical microscope and a scanning electron microscope of starch granules in leaves of a starch-type sweet potato after 18 days of seedling transplantation;

FIG. 2 is a drawing of an optical microscope and a scanning electron microscope of petiole starch grains 80 days after 18 seedlings of starch type sweet potato insertion;

FIG. 3 is a drawing of an optical microscope and a scanning electron microscope of stem starch grains 80 days after 18 seedlings of starch type sweet potatoes are transplanted;

table 1 shows the improvement and extraction efficiency of the present invention compared to the existing leaf starch extraction method.

Detailed Description

The present invention will be described in more detail with reference to the following examples and the accompanying drawings.