JPH0975029A - Treatment of sweet potato starch pulp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extract and purify a dietary fiber from a starch pulp produced in a sweet potato starch manufacturing process and to produce paper from the dietary fiber. SOLUTION: A sweet potato starch pulp is dried, passed through a sieve of about 30 mesh and suspended in water to recover the precipitated part of the suspension. The precipitated part is boiled with an aqueous solution of an alkali and bleached to give a pulp. The pulp is strained on a cloth and dried in a sandwiched state between two sheets of cloth to produce paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a purification method for converting starch meal produced as a by-product in the process of producing sweet potato starch into a food material, and a method for producing paper from it.

[0002]

BACKGROUND OF THE INVENTION Sweet potato starch meal was previously mostly consumed as feed. However, at present, only a part of it is taken over by the citric acid manufacturing plant as a fermentation raw material, and the rest is struggling to dispose of it such as spraying it on the field. The islands are also partially dried for transportation, but the dried meal also has only a small use as a wall treatment agent and oil adsorbent for civil engineering work.

In the production of sweet potato starch, since sweet potato is ground as it is, coarse ground and epidermal tissue are mixed in the ground product,
It is impossible to separate them by a wet sieving operation in the factory. In addition, it is very easy to perish, and it is accompanied by a bad smell mainly of butyric acid.
No attempt has been made to utilize this as a food ingredient. A small amount of citric acid-produced waste lees refined by alkali treatment or bleaching is only commercially available as dietary fiber in paste form.

Further, since the starch residue of sweet potato is derived from the ground material of sweet potato root, it does not contain fibers that can be produced by ordinary paper, and paper cannot be made by a conventional method. Therefore, starch meal has never been used as a raw material for paper.

[0005]

The main component of sweet potato starch meal is the cell wall of tuber root tissue, and if this part can be extracted and purified, it will open the way to edible use as dietary fiber. However, as mentioned above, in the sieving operation in the factory,
It is not possible to separate only the cell wall section.

On the other hand, since the sweet potato starch meal does not have a so-called fibrous form, even if it is made like paper, it will pass through the sieve net. Even if a fine cloth is used for the screen, and if the cake is hardened with a sizing material or the like, the felt-like brittle plate is still not in the form of paper.

[0007]

Means for Solving the Problems Sweet potato starch meal is first dried and passed through a sieve of about 30 mesh. Next, when this passage part is suspended and stirred in water and left to stand, it is divided into a precipitation part and a floating part, and the precipitation part is recovered. When it is dried, it is dehydrated by pressing or centrifugation as soon as possible.

Further, the precipitate part becomes a pulp when boiled in a dilute aqueous sodium hydroxide solution of about 1% and then bleached. It is excellent as a dietary fiber, and can be processed into paper by the following method. That is, in the paper manufacturing process, a cloth is laid on a sieve net to strain the pulp, and another cloth is covered on the pulp. Then, while still sandwiched between the two cloths, squeeze and dry as in the case of making a leaf sample of a plant,
Peel off the cloth after it is completely dry.

By the above operation, the fiber rich in cell wall components can be extracted and purified from the sweet potato starch meal, and it can also be made into a paper form. In addition, the whole starch meal, or the section that remains on the sieve during the purification or the section that floats in water, can be made paper-like by the same method as the above-mentioned precipitation part.

[0010]

Since sweet potato starch meal is difficult to purify in a wet state, it is essential to dry it first. The drying method is preferably a gas stream drying method used for drying starch,
The dried starch meal is thoroughly loosened and then passed through a sieve of about 30 mesh. Normally, 90 to 95% of the whole is passed through the sieve, but this operation can considerably separate and remove coarse muscle and epidermal tissue. The reason is that the epidermis and muscles tend to pass through the sieve softly in the raw state, but the shrinkage of the epidermis and muscles is small compared to the fact that the cell wall portion shrinks considerably due to drying. A sieve of about 30 mesh is optimal for separating both.

Next, when the dried starch meal of 30 mesh or less is suspended in water and stirred well, the cell wall portion rapidly precipitates because of its high affinity with water. It keeps floating. Since the precipitation part and the floating part are clearly separated by using the intermediate water layer, the floating part is removed to recover only the precipitation part. By this operation, most of the epidermal tissue and muscles that pass through the sieve are also removed. The percentage of precipitate is approximately 70 to 75%.

[0012] Since water does not sufficiently permeate to the deep part of the precipitate mainly composed of cell walls, if dehydrated by squeezing or centrifugation as quickly as possible, drying after dehydration is very easy. It should be noted that since many coarse particles remaining on the 30-mesh sieve will precipitate even if they are not hydrophilic, sieving as a pretreatment is necessary.

By the above operation, the portion rich in the cell wall of sweet potato can be extracted from the starch meal in a considerably pure state. Since minute starch granules adhere and remain inside the cell wall of sweet potato, about half of the weight of this purified sweet potato starch meal is starch.

Next, when the purified starch meal is boiled with a dilute aqueous solution of sodium hydroxide, the starch is dissolved and a part of pectin and lignin is removed to leave the fiber more pure. A sodium hydroxide concentration of about 1% is sufficient, and it may be much thinner than the usual pulpwood treatment. A suitable amount of the aqueous solution is about 20 times that of the starch meal. A white pulp is obtained by adding a bleaching treatment with sodium hypochlorite after the alkali treatment. This pulp, in the form of paste or dry powder, becomes a high-quality dietary fiber food material rich in water retention.

The cell wall component purified by such a treatment shrinks due to drying, but as described above, it is squeezed on a cloth and then covered with a cloth, and the plant is sandwiched between two cloths. By pressing and drying like a saw leaf sample, the original size paper is obtained. That is, it is only necessary to prevent lateral shrinkage by shrinking only the thickness. At this time, it is not necessary to add a sizing agent, and the weight of starch meal is about
A paper equivalent to 0% is obtained. Although the produced paper lacks water resistance as it is, it can be effectively used as a water-soluble or edible special paper. Alternatively, a water resistant coating may be applied. If this papermaking method is used,
It is possible to mold all the sections separated in the starch meal refining stage into paper, and obtain papers with unique textures and uses.

[0016]

Example 1 100 g of dried sweet potato starch meal was sieved through a 30-mesh sieve to obtain about 90 g of passage section. 2000c
This was suspended in water of c, stirred sufficiently, and allowed to stand, and the floating part and the precipitation part were separated in about 5 minutes, so only the precipitation part was recovered. About half of the settled portion was put into a cloth, squeezed tightly, spread on a newspaper and air dried. When it was sifted through a 50-mesh screen as it was, about 25 g of fine-grain purified starch meal was obtained. The residue on the sieve was about 5 g.

On the other hand, after adding 1000 cc of water to an enameled pot to dissolve 10 g of sodium hydroxide, the remaining half amount of the precipitate was added and boiled for about 10 minutes. After filtering with a colander covered with cotton cloth and removing some of the alkali with running water,
Again, it was decolorized by boiling in a solution of 10 cc of bleach (commercially available Higher) in 1000 cc of water for about 5 minutes. The cloth was again put into a cotton cloth, squeezed, and rubbed in running water to wash away the bleach, and then the remaining pulp was divided into 2 minutes.

One half is wrapped in a cloth and squeezed, and the juice that has been sufficiently squeezed is spread in a shallow vat and then blown dry (EYEL).
A: WFO-600ND) was used and it dried at 60 degreeC for 10 hours. After that, small household mills (SANYO: S
It was pulverized with M-M7) and passed through a 50-mesh sieve to obtain 3.5 g of white fine powder.

The remaining half of the pulp was suspended in 500 cc of water, and the pulp was placed in a paper-slot frame of a postcard size lined with cotton cloth and spread by a quarter to a uniform thickness. After draining the water, the frame was removed, another cotton cloth was put on the top, and a cloth for absorbing water was placed on top and bottom to weigh it for dehydration. After that, as in the case of making plant specimens, I squeezed it between the upper and lower cotton cloths with a dry newspaper, squeezed it, and completely dried it before peeling it off. Four sheets of white paper having a thickness as thin as a normal Japanese paper and fine and slightly transparent were obtained, and the total weight was about 4 g.

[0020]

Example 2 Dried starch meal is sieved through a 30 mesh screen,
50 g of the section remaining on the sieve was collected. This was further passed through a 9-mesh sieve to remove coarse impurities, and then, in exactly the same manner as in Example 1, boiled in 1000 cc of a 1% sodium hydroxide aqueous solution and bleached to prepare paper. Since the raw material was red peeled sweet potato, the fragments of the epidermis remained brown, and it became a strong paper consisting mainly of this epidermis and long yellow streaks. Ten sheets were obtained and the total weight was about 12 g. Further, the shrinkage rate was smaller than that of the paper of Example 1, and the production was easy.

[0021]

[Example 3] The whole starch meal and the water floating portion in Example 1 were pulped according to Example 1 to prepare paper. In all cases, the yield was around 20%. The paper from the water suspension is similar to the paper of Example 2 but with a finer texture. The paper made from the whole starch meal became a beautiful paper with a mixture of brown skin and yellow streaks on a slightly transparent substrate.

[0022]

EFFECTS OF THE INVENTION Sweet potato is an important agricultural crop in southern Kyushu, but the starch meal discharged as a by-product in the starch manufacturing industry, which is the largest utilization industry, has hardly been used so far. INDUSTRIAL APPLICABILITY The present invention has paved the way for its use as a foodstuff by extracting cell wall components, which are excellent dietary fibers, from sweet potato starch meal. At the same time, it became possible to manufacture paper from starch meal.

If all of the sweet potato starch meal, which was a troublesome waste and caused pollution of bad odors and water pollution, could be effectively used, it would be epoch-making in the sweet potato starch industry, and its economic effect is It is enormous. Most of the paper used in Japan today is made from imported wood pulp. In recent years, when global depletion of forest resources has become a concern, paper called non-wood paper made from first-year plant materials other than wood has been attracting attention. It has already been reported that the technology for making paper from kenaf, plants such as moroheiya, straw, reed, and peach, and industrial waste such as bagasse and peel meal has been established, and that paper has been made from okara. While research is being made to make paper from sweet potato vines, the implementation of the present invention is also an effective part of the non-wood paper movement that protects the global environment.

Claims (4)

[Claims] 1. A method in which starch meal produced in the process of producing sweet potato starch is dried, passed through a sieve of about 30 mesh and then suspended in water to be separated into a floating portion and a precipitation portion, and the precipitation portion is recovered. The method for purifying sweet potato starch meal. 2. A method for producing a purified sweet potato fiber, which comprises suspending the precipitate obtained by the method according to claim 1 in an aqueous solution of sodium hydroxide having a concentration of about 1%, boiling and bleaching. 3. A refined paper, characterized in that the refined sweet potato fiber according to claim 2 is strained on a cloth, and the cloth is covered with the cloth and dried while being sandwiched between two cloths. Manufacturing method. 4. A method for producing a starch meal paper, wherein paper is produced from the sweet potato starch meal or a by-product obtained during the method according to claim 1 by the method according to claims 2 and 3.