Title of Invention	"A PROCESS FOR MANUFACTURING XYLOOLIGOSACCHARIDES"
Abstract	The present invention discloses a process for manufacturing xyloligosaccharides, comprising : steaming a corncob meal under conditions of a temperature of 150 to 250°C and a pressure of 20 to 29MPa; filtering the steamed corncob meal to obtain a filtrate from which solid has been removed; performing an enzyme treatment by reacting xylanase with soluble xylan in the filtrate to hydrolyze the soluble xylan; removing any suspended matter from a reaction product obtained during the enzyme treatment; and drying the reaction product.

Title of Invention

"A PROCESS FOR MANUFACTURING XYLOOLIGOSACCHARIDES"

Abstract

The present invention discloses a process for manufacturing xyloligosaccharides, comprising : steaming a corncob meal under conditions of a temperature of 150 to 250°C and a pressure of 20 to 29MPa; filtering the steamed corncob meal to obtain a filtrate from which solid has been removed; performing an enzyme treatment by reacting xylanase with soluble xylan in the filtrate to hydrolyze the soluble xylan; removing any suspended matter from a reaction product obtained during the enzyme treatment; and drying the reaction product.

Full Text	BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a process for manufacturing xylooligosaccharides, which are useful as sweetening agents. This application is divided out of Indian Application No. 281/KOL/2003, hereinafter called the "parent" application. DESCRIPTION OF THE RELATED ART Biodegradable plastic is a plastic, which, like any ordinary plastic, exhibits excellent functions when in use, but which is quickly decomposed by microorganisms in a natural environment (for example, in the soil) after use and eventually becomes an organic components of earth, water and carbon dioxide, and is drawing attention in connection with the current problem of waste, etc. Various kinds of biodegradablje.plaatiG-products-lrave^Been publicized. Examples of. such products include polylactic acids produced by dehydration and polymerization from lactic acid obtained by fermenting starch of corn, potatoes, etc. with lactobacilli. Such products are used for an agricultural 1 A multi- film, a compost bag, etc. However, prices of raw materials and processing costs for products are high, and these products are not necessarily rational in consideration of foodfoodstuff situations in the future. Polycaprolactone, which is given as another example of a biodegradable plastic, is also so expensive that it is difficult to use polycaplolactone as an agricultural material, etc., and use is limited to medical materials, etc., although polycaplolactone may be satisfactory in physical properties as a plastic and biodegradability. Moreover, a plastic obtained merely by kneading corn starch with polyethylene is being sold as a biodegradable plastic. This plastic, however, is not a biodegradable plastic in the true sense of the word, since it has become clear that, although its constituent, which is derived from natural matter, such as starch, may be biodegradable, polyethylene does not undergo any change (decomposition) . Such a product is being driven out of the market despite its low price. Thus, spreading of the biodegradable plastics, which have been heretofore known, has been slow because of their unsatisfactory performance, or because they require a complicated process for manufacture and their prices are high. The demand for biodegradable plastic products is, however, expected to increase more and more in the future for protection of the global environment, and accordingly, there is a desire 2 for the development of products having higher performance and lower costs. Under these circumstances, studies are being performed for a biodegradable plastic composed mainly of cellulose, which plants contain in a large quantity, or a derivative thereof . However, a high cost of manufacture of this biodegradable plastic is a problem, as is the case with other biodegradable plastics. On the other hand, the majority of a corncob is composed of cellulose (lignocellulose and hemicellulose) . Corncob meal, which is obtained by drying and crushing corncobs, is used as a fungal bed for growing mushrooms, an abrasive for pulse, a nest building material for animals, etc., but very little as an industrial material. The greater part of the corncobs produced is thrown away as waste. Incineration is a main method for waste disposal, thus, there are a lot of problems with waste disposal including degradation of the environment. Study is, therefore, under way for the effective use of corncobs. When corncobs are used as a raw material for manufacturing a biodegradable plastic consisting mainly of cellulose or a derivative thereof, etc. , the cost of the raw material is zero, as hardly any labor is required for gathering the raw material, etc., and costs that have hitherto been borne by agricultural producers for waste disposal are no longer incurred. Accordingly, a biodegradable plastic made from corncobs is considered to be highly price-competitive, compared to other 3 biodegradable plastics. However, despite having the features mentioned, there has not been developed any biodegradable plastic consisting mainly of cellulose or a derivative thereof, etc. made from corncobs. A possible reason for this is a high cost of esterification, etc., since it is difficult to obtain cellulose (pulp of high quality) by separating lignin from lignocelluloses of which corncobs mainly consist. The separation of lignin from lignocelluloses requires a lot of steps, i.e. grinding corncobs in a stone mill, boiling with alkali and applying a sulfurous acid treatment. Xylooligosaccharide is a beneficial saccharide which is generally used in lactic acid bacteria beverages, chocolate or the like which are qualified as foods for specified health uses of functioning for mauitaining the condition of the digestive system by an effect of selective promotion of intestinal bacterial growth. Xylooligosaccharide is also used as an emulsifier or a skin moisturizer in the fields of medication and sanitary products. In addition to utilization in foods for humans, xylooligosaccharide is used as an additive for fodder for animals. In general, most of the oligosaccharides which are used in foods for specified health uses have an effect of controlling intestinal condition, namely, of reducing the number of bacteria having negative effects such as Escherichia coli or Clostridium bacteria which are known as intestinal putrefaction microbes, and thereby increasing the relative number of Bifidobacteria which are known as bacteria having positive effects. For example, wheat bran, which is a polysaccharide consisting of hemicellulose hajving a xylan as a main chain thereof, is plant fiber that is difficult to digest and is added to foods as an intestinal condition-controlling component. Xylose, which is a raw material for forming xylooligosaccharide, is contained in wood materials in a large amount. Methods for producing xylooligosaccharide by extracting xylans from such wood materials have been conventionally implemented. Further, methods for producing xylooligosaccharide from a reaction filtrate obtained by treating pulp with hemicellulase have been proposed (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2000-333692). 4 On the other hand, corncob meal, which is obtained by drying and crashing corn cobs, is utilized as culture beds far cultivating mushrooms, abrasives for beans, nest building materials for animals and the like. However, the amount of corncob meal used as an industrial material is very small, and most generated corncob meal is currently disposed of as a waste material- Further, a majority of the disposal methods are based on mcineration and are thus problematic due to causing environmental deterioration. In view of the above, effective utilization of corncob meal is currently being studied. SUMMARY OF THE INVENTION The invention described in the "parent" application solves the problems as stated above and provides an inexpensive process for manufacturing cellulose acetate that is useful as a biodegradable plastic by using as a raw material a corncob meal which has hitherto been thrown away The present invention provides a process for manufacturing xylooligosaccharides, which are useful as sweetening agents, from a by-product occurring in the manufacture of cellulose acetate. Specifically, the invention described in the "parent" application provides a process for manufacturing cellulose acetate, which comprises the steps of : steaming a corncob meal at a temperature of 150 to 250°C and a pressure of 20 to 29MPa; filtering the steamed, cornco: 4A meal to obtain a solid product; and dehydrating and acetylating of adding acetic anhydride and sulfuric acid to the solid product. The present invention provides a process for manufacturing xylooligosaccharides, comprising : steaming a corncob meal under conditions of a temperature of 150 to 250°C and a pressure of 20 to 29MPa; filtering the steamed corncob meal to obtain a filtrate from which solid has been removed; performing an enzyme treatment by reacting xylanase with soluble xylan in the filtrate to hydrolyze the soluble xylan; removing any suspended matter from a reaction product obtained during the enzyme treatment; and drying the reaction product. BRIEF DESCRIPTION OP THE ACCOMPANYING DRAWING Fig. 1 is a partial sectional view of an extruder having a pressure-sealed cylinder as an example of a pressure vessel for carrying out the steaming treatment according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The process for manufacturing xylooligosaccharides of the present invention is characterized by steaming corncob meal at a temperature of 150 to 2500C and a pressure of 20 to 29 MPa (which may hereinafter be referred to as steaming treatment), then separating a solid product from a filtrate. The steaming treatment according to the present invention is a process of adding water to the corncob meal (a powder obtained by drying and crushing corncobs) and steaming the mixture at 150 to 250°C and 20 to 29 MPa, which are defining the conditions for the sub-critical state (immediately before the supercritical). The steaming treatment according to the present invention makes it possible to carry out in a simple and convenient way the separation of lignin from 5A lignocelluloses which has hitherto required a lot of steps. The steaming treatment requires a temperature of 150 to 250°C and a pressure of 20 to 29 MPa, and preferably a temperature of 180 to 200°C and a pressure of 25 to 28 MPa. The amount of water added is preferably 10 to 1000 parts by weight and more preferably 50 to 100 parts by weight, relative to 100 parts by weight of corncob meal. The steaming treatment is preferably carried out for 10 to 30 minutes, and more preferably for 15 to 20 minutes. Moreover, in the steaming treatment, a sulfurous acid compound may be added to the corncob meal- The addition of the sulfurous acid compound to the corncob meal makes it possible to shorten the time for the steaming treatment. Examples of the sulfurous acid compound include be sodium or calcium sulfite. The amount of the sulfurous acid compound which is added is preferably 1 to 10 parts by weight, and more preferably 2 to 5 parts by weight, for 100 parts by weight of corncob meal. The steaming treatment is preferably carried out by using a pressure vessel, and is particularly preferably carried out by, an extruder having a pressure-sealed cylinder as shown in Fig. 1. Fig. 1 is a partial sectional view of an extruder having a pressure-sealed cylinder, which is an example of a pressure vessel for carrying out the steaming treatment according to the present invention. The extruder is composed of: a cylinder 1 having a material input port 2 at its base; a screw 3 having 6 a spiral flight 4 for kneading (steaming) and extruding toward its distal end the corncob meal and water (which may hereinafter be referred to simply as the materials), which were inputted through the material input port 2; a heater 5 for heating the cylinder 1; drive means 6 including a motor 7 connected to a power source (not shown) for rotating the screw 3 and a reduction gear 8 having a prime gear 9 and a driven gear 10; a discharging port 11 for discharging a steamed and extruded product; a heat insulating material 12 covering the cylinder 1 and the heater 5, etc. A pump (not shown) is connected with the material input port 2 for feeding the materials into the cylinder 1 through the material input port 2. A pitch of the spiral flight 4 of the screw 3 shortens as the spiral flight 4 approaches the discharging port 11. Moreover, the cylinder 1 has a temperature sensor 13 and a pressure sensor 14 installed near the distal end of the screw 3. The steaming treatment is carried out by the extruder, which is shown in Fig. 1, in accordance with the following sequence . The materials are inputted by the unillustrated pump into the cylinder 1 through its material input port 2 and the internal temperature of the cylinder 1 is regulated to a target temperature by the heater 5. As viewed from the motor 7, a rotary shaft of the motor 7 rotated clockwise to rotate the primer gear 9 clockwise, the driven gear 10 counterclockwise and the screw 3 counterclockwise, thus boiling the corncob meal 7 while extruding the corncob meal toward the discharging port 11. Since the pitch of the spiral flight 4 of the screw 3 shortens toward the discharging port 11, the corncob meal is compressed and subjected to a specific pressure as it approaches the discharging port 11. The corncob meal, for which the steaming treatment has been completed, is extruded through the discharging port 11. While, in the present embodiment, the temperature sensor 13 and the pressure sensor 14 are installed in the cylinder 1 near the distal end of the screw 3, it is sufficient for an installation position of the temperature sensor 13 further to distal end side of the screw 3 than a middle portion, with respect to the axial direction, of the cylinder 1. It is sufficient for an installation position the pressure sensor 14 to be in a space, which is a distal-end of the screw 3 of the cylinder 1. When the steaming treatment is carried out by the extruder shown in Fig. 1, it is necessary for the temperature and pressure determined by the temperature sensor 13 and the pressure sensor 14 to fall within the ranges of 150 to 250°C and 20 to 29 MPa, respectively. Moreover, it is also suitable to employ a process in which two or more units of extruder shown in Fig. 1 are connected in series for steaming treatment, i.e. a process in which a mixture of corncob meal and water steamed in a first extruder and 8 extruded through a discharging port 11 thereof is directly inputted into the material input port 2 of a second extruder for further steaming. When two or more units of extruder shown in Fig. 1 are connected in series for the steaming treatment, the steaming conditions in the extruders may be the same, or differ from one another as long as the steaming conditions for the last connected extruder satisfy the conditions of the temperature of 150 to 250°C and the pressure of 20 to 29 MPa. In the case which the steaming conditions differ from one extruder to another, it is preferable for the temperature and pressure to rise from the first extruder to the last connected extruder. The steaming treatment of the corncob meal as described above obtains a mixture of polyphenol (formed by a change from the lignin) and cellulose which are formed by the decomposition of lignocelluloses, and of soluble hemicelluloses {hereinafter referred to as soluble xylan) . The filtration treatment of the mixture enables it to be separated into cellulose (pulp of high quality) as a solid and a mixed solution of polyphenol and soluble xylan. The filtration treatment is preferably carried out by a filtering device. The cellulose obtained by separating lignin with the filtration treatment is crystallized due to the formation of hydrogen bonds by the hydroxyl groups and is insoluble in both water and any solvent. Therefore, dehydrating and acetylating 9 is carried out as described below for converting a portion of hydroxyl groups in the molecule to acetate groups to obtain a plasticized cellulose acetate, which is soluble in both water and a solvent. The dehydrating and acetylating is preferably carried out in a pressure vessel equipped with a stirrer. The dehydrating and acetylating is intended for reacting cellulose with acetic anhydride and sulfuric acid to substitute acetate groups for the hydroxyl groups, causing the formation of hydrogen bonds in the cellulose, and is expressed by reaction formulae (1) and (2) below when n is the degree of polymerization and m is the degree of substitution. Reaction formula (1) {C6H702(OH)3}n + 3n(CH3CO)20 -> {C6H702 (OCOCH3) 3} n + 3nCH3COOH Reaction formula (2) {C6H702(OCOCH3)3}n + n(3-m)H20 -> {C6H702 (OCOCH3) n (OH) 3.m} n + n(3-m)CH3COOH Reaction formula (1) shows that the reaction of cellulose and acetic anhydride produces cellulose acetate and acetic acid with the complete substitution of acetate groups. On the other hand, reaction formula (2) shows that the reaction of cellulose acetate produced in accordance with reaction formula (1) and water produces cellulose acetate having a degree of substitution m and acetic acid. The acetic acid produced in accordance with reaction formulae (1) and (2) can be reused. The dehydrating and acetylating can be carried out in 10 accordance with the following sequence. After the solid (cellulose) obtained by the filtration treatment is washed with water to remove alkali therefrom, sulfuric acid and acetic anhydride are added to and reacted with the obtained solid, acetic acid is removed (collected) from the resulting reaction product by a dehydrator, and is dried. The above procedure obtains cellulose acetate having an acetylation degree of 51 to 61. The amount of sulfuric acid which is added is preferably 1 to 10 parts by weight and more preferably 3 to 5 parts by weight relative to 100 parts by weight of dry cellulose. The amount of acetic anhydride which is added is preferably 1 to 20 parts by weight and more preferably 5 to 10 parts by weight, relative to 100 parts by weight of dry cellulose. Moreover, acetic acid can be preferably added, and the amount thereof added is preferably 1 to 10 parts by weight and more preferably 3 to 5 parts by weight relative to 100 parts by weight of cellulose. The dehydration and acetylation is preferably carried out under a pressure of 5 to 15 MPa, and more preferably 8 to 10 Mpa. The temperature for the dehydration and acetylation is preferably from 60 to 100°C and more preferably from 70 to 90°C. The stirring speed for the dehydration and acetylation is preferably from 30 to 100 rpm and more preferably from 40 to 60 rpm. The duration of the dehydration and acetylation is preferably from 15 to 30 hours and more preferably from 20 to 11 24 hours. While cellulose acetate is a biodegradable plastic itself, it is also possible to use cellulose acetate as a base and knead various kinds of materials (for example, corn starch and polylactic acid) therein to make biodegradable plastics of different properties. On the other hand, soluble xylan obtained by the filtration treatment becomes xylooligosaccharideis by hydrolytic treating (enzyme treatment) xylanase. The enzyme treatment can be carried out in the following sequence: xylanase is added to and reacted with the filtrate from which the solid was removed by the filtering device, in a reaction vessel equipped with a stirrer and having a temperature holding mechanism; any suspended matter is removed from the resulting reaction product by the filtering device and is dried, xylooligosaccharideis are obtained by the above sequence. The amount of xylanase added in the enzyme treatment is preferably from 0.l to 5 partrs by weight and more preferably from 0.5 to 2 parts by weight relative to 100 parte by weight of filtrate. The enzyme treatment is preferably carried out at a pH of 3 to 8 and more preferably at a pH of 4 to 6. Moreover, the temperature for the treatment is preferably from 30 to 50°C and more preferably from 4 0 to 45°C. The stirring speed is preferably from 60 to 200 rptn and more preferably from 100 to 150 rpm. The duration of the treatment is preferably-from 15 12 to 3 0 hours and is more preferably from 20 to 24 hours. While the enzyme treatment converts soluble xylan into xylooligosaccharides (sweetening agents) , the soluble xylan by-product and this step can be omitted without the process for manufacturing a biodegradable plastic, but the addition of the step makes it possible to achieve an outstanding increase in the efficiency of use of raw materials, reduction of wastes, and also the auxiliary production of useful products. In other words, the enzyme treatment can lower the cost of manufacture of cellulose acetate. Incidentally, xylooligosaccharides are used in various kinds of food owing to their effect of preventing tooth decay and establishing a good balance of colif orm bacteria for health promotion, and demand for xylooligosaccharides is expected to increase greatly in the future. EXAMPLES The invention will now be described more specifically by way of examples, though the invention is not limited these examples. Example 1 The steaming of a corncob meal was carried out by four serially connected units of pressure-sealed extruder as shown in Fig. 1. The four serially connected extruders included a first extruder with a discharging port 11 thereof connected to a material input port 2 of a second extruder, and the rest were 13 likewise connected until a fourth extruder, so that a kneaded mixture steamed in the first extruder could be inputted into the cylinder 1 of the second extruder directly through the material input port 2 and thereof could thereafter likewise proceed until it reached the material input port 2 of the fourth extruder. Five parts by weight of calcium sulfite and 50 parts by weight of water were added relative to 100 parts by weight of a corncob meal, and were inputted through its material input port 2 into the cylinder 1 of the pressure-sealed extruder as shown in Fig. 1. Then, the temperature and pressure of the first extruder were set to the values stated in Table 1, the motor was driven to rotate the screw 3 and after five minutes of kneading (steaming) , a knealed product was extruded through the discharging port 11. The kneaded product extruded through the discharging port 11 was inputted directly into the cylinder 1 of the second extruder through its material input port 2, and kneading (steaming) was likewise repeated to the fourth extruder. The conditions set and kneading (steaming) time for each extruder are as shown in Table 1. The temperature and pressure stated in Table 1 are the values as determined by the temperature sensor 13 and the pressure sensor 14, respectively. 14 Table 1 First extruder Second extruder Third extruder Fourth extruder Temperature (°C) 100 150 200 220 Pressure (MPa) 3.5 10 22 28 Time for treatment (min) 5 5 5 15 The corncob meal which had been steamed by the four serially connected extruders was filtered by a filtering device, the resulting solid (cellulose) was inputted into a pressure vessel equipped with a stirrer and after was 5 parts by weight of acetic acid, 10 parts by weight of acetic anhydride and 5 parts by weight of sulfuric acid for 100 parts by weight of solid were further inputted into the pressure vessel, the mixture was reacted for 24 hours at a pressure of 10 MPa and a stirring speed of 60 rpm to yield cellulose acetate. The physical properties of cellulose acetate obtained are shown in Table 2. Table 2 Outward shape White flaky powder Specific gravity 1.33 (25°C) , 1.36{4°C) Bulk density (Kg/L) 0.25 - 0.5 Glass transition temperature (°C) 160 - 180°C Melting point (°C) 230 - 300°C The filtrate from which the solid had been removed by the filtration of the steamed corncob meal by the filtering device was inputted into a reaction vessel equipped with a stirrer and having a temperature holding mechanism. After 3 parts by weight 15 of xylanase and 0.1 part by weight of sodium hydroxide for 100 parts by weight of filtrate were inputted into the reaction vessel, the mixture was reacted for 24 hours at a temperature of 45°C and a stirring speed of 150 rpm to yield xylooligosaccharides. The steaming treatment of corncob meal according to the present invention has made it possible to carry out in a single step the removal of lignin from lignocelluloses which has hitherto required a lot of steps, and. obtain xylooligosaccharides from the treatment of soluble xylan (which has hitherto been thrown away) produced by the steaming and by its hydrolytic treatment (enzyme treatment) with the enzyme xylanase. The present invention is an inexpensive process for manufacturing xylooligosaccharides useful as sweetening agents. 16 WE CLAIM: 1. A process for manufacturing xylooligosaccharides, comprising: steaming a corncob meal under conditions of a temperature of 150 to 250°C and a pressure of 20 to 29MPa; filtering the steamed corncob meal to obtain a filtrate from which solid has been removed; performing an enzyme treatment by reacting xylanase with soluble xylan in the filtrate to hydrolyze the soluble xylan; removing any suspended matter from a reaction product obtained during the enzyme treatment; and drying the reaction product 2. A process as claimed in claim 1, wherein the steaming is carried out in a pressure vessel and the filtering is carried out by a filtering device. 3. A process as claimed in claim 1, wherein the steaming is carried out under conditions of a temperature of 180 to 200°C and a pressure of 25 to 28 Mpa. 4. A process as claimed in claim 1, wherein, in the steaming, 10 to 1000 parts by weight of water is added relative to 100 parts by weight of corncob meal. 5. A process as claimed in claim 1, wherein the steaming is carried out for 10 to 30 minutes. 6. A process as claimed in claim 1, wherein, in the steaming, a sulfurous acid compound is added to the corncob meal. 7. A process as claimed in claim 6, wherein the sulfurous acid compound is added in the amount of 1 to 10 parts by weight for 100 parts by weight of the corncob meal. 8. A process as claimed in claim 1, wherein the xylanase is added in the amount of 17 0.1 to 5 parte by weight relative to 100 parts by weight of the filtrate. 9. A process as claimed in claim 1, wherein the enzyme treatment is carried out under conditions of a pH of 3 to 8, a temperature of 30 to 50°C, a stirring speed of 60 to 200 rpm and a treatment time of 15 to 30 hours, 10. A process as claimed in claim 1, wherein the steaming is performed by two or more sequentially connected extruders having pressure-sealed cylinders; the levels of temperature and pressure set rise gradually, beginning with the first connected extruder until the last connected extruder; and the steaming conditions for the last connected extruder satisfy the conditions of a temperature of 150 to 250°C and a pressure of 20 to 29 Mpa. 11. A process for manufacturing xylooligosaccharides, substantially as herein described, particularly with reference to the examples. The present invention discloses a process for manufacturing xyloligosaccharides, comprising : steaming a corncob meal under conditions of a temperature of 150 to 250°C and a pressure of 20 to 29MPa; filtering the steamed corncob meal to obtain a filtrate from which solid has been removed; performing an enzyme treatment by reacting xylanase with soluble xylan in the filtrate to hydrolyze the soluble xylan; removing any suspended matter from a reaction product obtained during the enzyme treatment; and drying the reaction product.

Full Text

BACKGROUND OF THE INVENTION Field of the invention
The present invention relates to a process for manufacturing xylooligosaccharides, which are useful as sweetening agents. This application is divided out of Indian Application No.
281/KOL/2003, hereinafter called the "parent" application. DESCRIPTION OF THE RELATED ART
Biodegradable plastic is a plastic, which, like any
ordinary plastic, exhibits excellent functions when in use, but
which is quickly decomposed by microorganisms in a natural
environment (for example, in the soil) after use and eventually
becomes an organic components of earth, water and carbon dioxide,
and is drawing attention in connection with the current problem
of waste, etc.
Various kinds of biodegradablje.plaatiG-products-lrave^Been
publicized. Examples of. such products include polylactic
acids produced by dehydration and polymerization from lactic
acid obtained by fermenting starch of corn, potatoes, etc. with
lactobacilli. Such products are used for an agricultural
1 A

multi- film, a compost bag, etc. However, prices of raw materials and processing costs for products are high, and these products are not necessarily rational in consideration of foodfoodstuff situations in the future. Polycaprolactone, which is given as another example of a biodegradable plastic, is also so expensive that it is difficult to use polycaplolactone as an agricultural material, etc., and use is limited to medical materials, etc., although polycaplolactone may be satisfactory in physical properties as a plastic and biodegradability.
Moreover, a plastic obtained merely by kneading corn starch with polyethylene is being sold as a biodegradable plastic. This plastic, however, is not a biodegradable plastic in the true sense of the word, since it has become clear that, although its constituent, which is derived from natural matter, such as starch, may be biodegradable, polyethylene does not undergo any change (decomposition) . Such a product is being driven out of the market despite its low price.
Thus, spreading of the biodegradable plastics, which have been heretofore known, has been slow because of their unsatisfactory performance, or because they require a complicated process for manufacture and their prices are high. The demand for biodegradable plastic products is, however, expected to increase more and more in the future for protection of the global environment, and accordingly, there is a desire
2

for the development of products having higher performance and lower costs. Under these circumstances, studies are being performed for a biodegradable plastic composed mainly of cellulose, which plants contain in a large quantity, or a derivative thereof . However, a high cost of manufacture of this biodegradable plastic is a problem, as is the case with other biodegradable plastics.
On the other hand, the majority of a corncob is composed of cellulose (lignocellulose and hemicellulose) . Corncob meal, which is obtained by drying and crushing corncobs, is used as a fungal bed for growing mushrooms, an abrasive for pulse, a nest building material for animals, etc., but very little as an industrial material. The greater part of the corncobs produced is thrown away as waste. Incineration is a main method for waste disposal, thus, there are a lot of problems with waste disposal including degradation of the environment. Study is, therefore, under way for the effective use of corncobs.
When corncobs are used as a raw material for manufacturing a biodegradable plastic consisting mainly of cellulose or a derivative thereof, etc. , the cost of the raw material is zero, as hardly any labor is required for gathering the raw material, etc., and costs that have hitherto been borne by agricultural producers for waste disposal are no longer incurred. Accordingly, a biodegradable plastic made from corncobs is considered to be highly price-competitive, compared to other
3

biodegradable plastics.
However, despite having the features mentioned, there has
not been developed any biodegradable plastic consisting mainly
of cellulose or a derivative thereof, etc. made from corncobs.
A possible reason for this is a high cost of esterification,
etc., since it is difficult to obtain cellulose (pulp of high
quality) by separating lignin from lignocelluloses of which
corncobs mainly consist. The separation of lignin from
lignocelluloses requires a lot of steps, i.e. grinding corncobs
in a stone mill, boiling with alkali and applying a sulfurous
acid treatment.
Xylooligosaccharide is a beneficial saccharide which is generally used in lactic acid
bacteria beverages, chocolate or the like which are qualified as foods for specified health uses of functioning for mauitaining the condition of the digestive system by an effect of selective promotion of intestinal bacterial growth. Xylooligosaccharide is also used as an emulsifier or a skin moisturizer in the fields of medication and sanitary products. In addition to utilization in foods for humans, xylooligosaccharide is used as an additive for fodder for animals.
In general, most of the oligosaccharides which are used in foods for specified health uses have an effect of controlling intestinal condition, namely, of reducing the number of bacteria having negative effects such as Escherichia coli or Clostridium bacteria which are known as intestinal putrefaction microbes, and thereby increasing the relative number of Bifidobacteria which are known as bacteria having positive effects. For example, wheat bran, which is a polysaccharide consisting of hemicellulose hajving a xylan as a main chain thereof, is plant fiber that is difficult to digest and is added to foods as an intestinal condition-controlling component.
Xylose, which is a raw material for forming xylooligosaccharide, is contained in wood materials in a large amount. Methods for producing xylooligosaccharide by extracting xylans from such wood materials have been conventionally implemented. Further, methods for producing xylooligosaccharide from a reaction filtrate obtained by treating pulp with hemicellulase have been proposed (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2000-333692).
4

On the other hand, corncob meal, which is obtained by drying and crashing corn cobs, is utilized as culture beds far cultivating mushrooms, abrasives for beans, nest building materials for animals and the like. However, the amount of corncob meal used as an industrial material is very small, and most generated corncob meal is currently disposed of as a waste material- Further, a majority of the disposal methods are based on mcineration and are thus problematic due to causing environmental deterioration. In view of the above, effective utilization of corncob meal is currently being studied.
SUMMARY OF THE INVENTION
The invention described in the "parent" application solves the problems as stated above and provides an inexpensive process for manufacturing cellulose acetate that is useful as a biodegradable plastic by using as a raw material a corncob meal which has hitherto been thrown away The present invention provides a process for
manufacturing xylooligosaccharides, which are useful as sweetening agents, from a by-product occurring in the manufacture of cellulose acetate.
Specifically, the invention described in the "parent" application provides a process for manufacturing cellulose acetate, which comprises the steps of : steaming a corncob meal at a temperature of 150 to 250°C and a pressure of 20 to 29MPa; filtering the steamed, cornco:
4A

meal to obtain a solid product; and dehydrating and acetylating of adding acetic anhydride and sulfuric acid to the solid product.
The present invention provides a process for manufacturing xylooligosaccharides, comprising : steaming a corncob meal under conditions of a temperature of 150 to 250°C and a pressure of 20 to 29MPa;
filtering the steamed corncob meal to obtain a filtrate from which solid has been removed;
performing an enzyme treatment by reacting xylanase with soluble xylan in the filtrate to hydrolyze the soluble xylan;
removing any suspended matter from a reaction product obtained during the enzyme treatment; and drying the reaction product.
BRIEF DESCRIPTION OP THE ACCOMPANYING DRAWING Fig. 1 is a partial sectional view of an extruder having a pressure-sealed cylinder as an example of a pressure vessel for carrying out the steaming treatment according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The process for manufacturing
xylooligosaccharides of the present invention is characterized by steaming corncob meal at a temperature of 150 to 2500C and

a pressure of 20 to 29 MPa (which may hereinafter be referred to as steaming treatment), then separating a solid product from a filtrate.
The steaming treatment according to the present invention is a process of adding water to the corncob meal (a powder obtained by drying and crushing corncobs) and steaming the mixture at 150 to 250°C and 20 to 29 MPa, which are defining the conditions for the sub-critical state (immediately before the supercritical). The steaming treatment according to the present invention makes it possible to carry out in a simple and convenient way the separation of lignin from
5A

lignocelluloses which has hitherto required a lot of steps.
The steaming treatment requires a temperature of 150 to 250°C and a pressure of 20 to 29 MPa, and preferably a temperature of 180 to 200°C and a pressure of 25 to 28 MPa. The amount of water added is preferably 10 to 1000 parts by weight and more preferably 50 to 100 parts by weight, relative to 100 parts by weight of corncob meal. The steaming treatment is preferably carried out for 10 to 30 minutes, and more preferably for 15 to 20 minutes.
Moreover, in the steaming treatment, a sulfurous acid compound may be added to the corncob meal- The addition of the sulfurous acid compound to the corncob meal makes it possible to shorten the time for the steaming treatment. Examples of the sulfurous acid compound include be sodium or calcium sulfite. The amount of the sulfurous acid compound which is added is preferably 1 to 10 parts by weight, and more preferably 2 to 5 parts by weight, for 100 parts by weight of corncob meal.
The steaming treatment is preferably carried out by using a pressure vessel, and is particularly preferably carried out by, an extruder having a pressure-sealed cylinder as shown in Fig. 1. Fig. 1 is a partial sectional view of an extruder having a pressure-sealed cylinder, which is an example of a pressure vessel for carrying out the steaming treatment according to the present invention. The extruder is composed of: a cylinder 1 having a material input port 2 at its base; a screw 3 having
6

a spiral flight 4 for kneading (steaming) and extruding toward its distal end the corncob meal and water (which may hereinafter be referred to simply as the materials), which were inputted through the material input port 2; a heater 5 for heating the cylinder 1; drive means 6 including a motor 7 connected to a power source (not shown) for rotating the screw 3 and a reduction gear 8 having a prime gear 9 and a driven gear 10; a discharging port 11 for discharging a steamed and extruded product; a heat insulating material 12 covering the cylinder 1 and the heater 5, etc. A pump (not shown) is connected with the material input port 2 for feeding the materials into the cylinder 1 through the material input port 2. A pitch of the spiral flight 4 of the screw 3 shortens as the spiral flight 4 approaches the discharging port 11. Moreover, the cylinder 1 has a temperature sensor 13 and a pressure sensor 14 installed near the distal end of the screw 3.
The steaming treatment is carried out by the extruder, which is shown in Fig. 1, in accordance with the following sequence . The materials are inputted by the unillustrated pump into the cylinder 1 through its material input port 2 and the internal temperature of the cylinder 1 is regulated to a target temperature by the heater 5. As viewed from the motor 7, a rotary shaft of the motor 7 rotated clockwise to rotate the primer gear 9 clockwise, the driven gear 10 counterclockwise and the screw 3 counterclockwise, thus boiling the corncob meal
7

while extruding the corncob meal toward the discharging port 11. Since the pitch of the spiral flight 4 of the screw 3 shortens toward the discharging port 11, the corncob meal is compressed and subjected to a specific pressure as it approaches the discharging port 11. The corncob meal, for which the steaming treatment has been completed, is extruded through the discharging port 11.
While, in the present embodiment, the temperature sensor
13 and the pressure sensor 14 are installed in the cylinder 1
near the distal end of the screw 3, it is sufficient for an
installation position of the temperature sensor 13 further to
distal end side of the screw 3 than a middle portion, with respect
to the axial direction, of the cylinder 1. It is sufficient
for an installation position the pressure sensor 14 to be in
a space, which is a distal-end of the screw 3 of the cylinder
1.
When the steaming treatment is carried out by the extruder shown in Fig. 1, it is necessary for the temperature and pressure determined by the temperature sensor 13 and the pressure sensor
14 to fall within the ranges of 150 to 250°C and 20 to 29 MPa,
respectively.
Moreover, it is also suitable to employ a process in which two or more units of extruder shown in Fig. 1 are connected in series for steaming treatment, i.e. a process in which a mixture of corncob meal and water steamed in a first extruder and
8

extruded through a discharging port 11 thereof is directly inputted into the material input port 2 of a second extruder for further steaming. When two or more units of extruder shown in Fig. 1 are connected in series for the steaming treatment, the steaming conditions in the extruders may be the same, or differ from one another as long as the steaming conditions for the last connected extruder satisfy the conditions of the temperature of 150 to 250°C and the pressure of 20 to 29 MPa. In the case which the steaming conditions differ from one extruder to another, it is preferable for the temperature and pressure to rise from the first extruder to the last connected extruder.
The steaming treatment of the corncob meal as described above obtains a mixture of polyphenol (formed by a change from the lignin) and cellulose which are formed by the decomposition of lignocelluloses, and of soluble hemicelluloses {hereinafter referred to as soluble xylan) . The filtration treatment of the mixture enables it to be separated into cellulose (pulp of high quality) as a solid and a mixed solution of polyphenol and soluble xylan. The filtration treatment is preferably carried out by a filtering device.
The cellulose obtained by separating lignin with the filtration treatment is crystallized due to the formation of hydrogen bonds by the hydroxyl groups and is insoluble in both water and any solvent. Therefore, dehydrating and acetylating
9

is carried out as described below for converting a portion of hydroxyl groups in the molecule to acetate groups to obtain a plasticized cellulose acetate, which is soluble in both water and a solvent. The dehydrating and acetylating is preferably carried out in a pressure vessel equipped with a stirrer.
The dehydrating and acetylating is intended for reacting cellulose with acetic anhydride and sulfuric acid to substitute acetate groups for the hydroxyl groups, causing the formation of hydrogen bonds in the cellulose, and is expressed by reaction formulae (1) and (2) below when n is the degree of polymerization and m is the degree of substitution. Reaction formula (1)
{C6H702(OH)3}n + 3n(CH3CO)20 -> {C6H702 (OCOCH3) 3} n + 3nCH3COOH Reaction formula (2)
{C6H702(OCOCH3)3}n + n(3-m)H20 -> {C6H702 (OCOCH3) n (OH) 3.m} n + n(3-m)CH3COOH
Reaction formula (1) shows that the reaction of cellulose and acetic anhydride produces cellulose acetate and acetic acid with the complete substitution of acetate groups. On the other hand, reaction formula (2) shows that the reaction of cellulose acetate produced in accordance with reaction formula (1) and water produces cellulose acetate having a degree of substitution m and acetic acid. The acetic acid produced in accordance with reaction formulae (1) and (2) can be reused.
The dehydrating and acetylating can be carried out in
10

accordance with the following sequence. After the solid (cellulose) obtained by the filtration treatment is washed with water to remove alkali therefrom, sulfuric acid and acetic anhydride are added to and reacted with the obtained solid, acetic acid is removed (collected) from the resulting reaction product by a dehydrator, and is dried. The above procedure obtains cellulose acetate having an acetylation degree of 51 to 61.
The amount of sulfuric acid which is added is preferably 1 to 10 parts by weight and more preferably 3 to 5 parts by weight relative to 100 parts by weight of dry cellulose. The amount of acetic anhydride which is added is preferably 1 to 20 parts by weight and more preferably 5 to 10 parts by weight, relative to 100 parts by weight of dry cellulose. Moreover, acetic acid can be preferably added, and the amount thereof added is preferably 1 to 10 parts by weight and more preferably 3 to 5 parts by weight relative to 100 parts by weight of cellulose. The dehydration and acetylation is preferably carried out under a pressure of 5 to 15 MPa, and more preferably 8 to 10 Mpa. The temperature for the dehydration and acetylation is
preferably from 60 to 100°C and more preferably from 70 to 90°C. The stirring speed for the dehydration and acetylation is preferably from 30 to 100 rpm and more preferably from 40 to 60 rpm. The duration of the dehydration and acetylation is preferably from 15 to 30 hours and more preferably from 20 to
11

24 hours.
While cellulose acetate is a biodegradable plastic itself, it is also possible to use cellulose acetate as a base and knead various kinds of materials (for example, corn starch and polylactic acid) therein to make biodegradable plastics of different properties.
On the other hand, soluble xylan obtained by the filtration treatment becomes xylooligosaccharideis by hydrolytic treating (enzyme treatment) xylanase. The enzyme treatment can be carried out in the following sequence: xylanase is added to and reacted with the filtrate from which the solid was removed by the filtering device, in a reaction vessel equipped with a stirrer and having a temperature holding mechanism; any suspended matter is removed from the resulting reaction product by the filtering device and is dried, xylooligosaccharideis are obtained by the above sequence. The amount of xylanase added in the enzyme treatment is preferably from 0.l to 5 partrs by weight and more preferably from 0.5 to 2 parts by weight relative to 100 parte by weight of filtrate. The enzyme treatment is preferably carried out at a pH of 3 to 8 and more preferably at a pH of 4 to 6. Moreover, the temperature for the treatment is preferably from 30 to 50°C and more preferably from 4 0 to 45°C. The stirring speed is preferably from 60 to 200 rptn and more preferably from 100 to 150 rpm. The duration of the treatment is preferably-from 15
12

to 3 0 hours and is more preferably from 20 to 24 hours.
While the enzyme treatment converts soluble xylan into xylooligosaccharides (sweetening agents) , the soluble xylan by-product and this step can be omitted without the process for manufacturing a biodegradable plastic, but the addition of the step makes it possible to achieve an outstanding increase in the efficiency of use of raw materials, reduction of wastes, and also the auxiliary production of useful products. In other words, the enzyme treatment can lower the cost of manufacture of cellulose acetate. Incidentally, xylooligosaccharides are used in various kinds of food owing to their effect of preventing tooth decay and establishing a good balance of colif orm bacteria for health promotion, and demand for xylooligosaccharides is expected to increase greatly in the future.
EXAMPLES
The invention will now be described more specifically by way of examples, though the invention is not limited these examples. Example 1
The steaming of a corncob meal was carried out by four serially connected units of pressure-sealed extruder as shown in Fig. 1. The four serially connected extruders included a first extruder with a discharging port 11 thereof connected to a material input port 2 of a second extruder, and the rest were
13

likewise connected until a fourth extruder, so that a kneaded mixture steamed in the first extruder could be inputted into the cylinder 1 of the second extruder directly through the material input port 2 and thereof could thereafter likewise proceed until it reached the material input port 2 of the fourth extruder.
Five parts by weight of calcium sulfite and 50 parts by weight of water were added relative to 100 parts by weight of a corncob meal, and were inputted through its material input port 2 into the cylinder 1 of the pressure-sealed extruder as shown in Fig. 1. Then, the temperature and pressure of the first extruder were set to the values stated in Table 1, the motor was driven to rotate the screw 3 and after five minutes of kneading (steaming) , a knealed product was extruded through the discharging port 11. The kneaded product extruded through the discharging port 11 was inputted directly into the cylinder 1 of the second extruder through its material input port 2, and kneading (steaming) was likewise repeated to the fourth extruder. The conditions set and kneading (steaming) time for each extruder are as shown in Table 1. The temperature and pressure stated in Table 1 are the values as determined by the temperature sensor 13 and the pressure sensor 14, respectively.
14

Table 1

First extruder Second extruder Third extruder Fourth extruder
Temperature (°C) 100 150 200 220
Pressure (MPa) 3.5 10 22 28
Time for treatment (min) 5 5 5 15
The corncob meal which had been steamed by the four serially connected extruders was filtered by a filtering device, the resulting solid (cellulose) was inputted into a pressure vessel equipped with a stirrer and after was 5 parts by weight of acetic acid, 10 parts by weight of acetic anhydride and 5 parts by weight of sulfuric acid for 100 parts by weight of solid were further inputted into the pressure vessel, the mixture was reacted for 24 hours at a pressure of 10 MPa and a stirring speed of 60 rpm to yield cellulose acetate. The physical properties of cellulose acetate obtained are shown in Table 2.
Table 2

Outward shape White flaky powder
Specific gravity 1.33 (25°C) , 1.36{4°C)
Bulk density (Kg/L) 0.25 - 0.5
Glass transition temperature (°C) 160 - 180°C
Melting point (°C) 230 - 300°C
The filtrate from which the solid had been removed by the filtration of the steamed corncob meal by the filtering device was inputted into a reaction vessel equipped with a stirrer and having a temperature holding mechanism. After 3 parts by weight
15

of xylanase and 0.1 part by weight of sodium hydroxide for 100 parts by weight of filtrate were inputted into the reaction vessel, the mixture was reacted for 24 hours at a temperature of 45°C and a stirring speed of 150 rpm to yield xylooligosaccharides. The steaming treatment of corncob meal according to the present invention has made it possible to carry out in a single step the removal of lignin from lignocelluloses which has hitherto required a lot of steps, and. obtain
xylooligosaccharides from the treatment of soluble xylan (which has hitherto been thrown away) produced by the steaming and by its hydrolytic treatment (enzyme treatment) with the enzyme xylanase.
The present invention is an inexpensive process for manufacturing xylooligosaccharides useful as sweetening agents.
16

WE CLAIM:
1. A process for manufacturing xylooligosaccharides, comprising:
steaming a corncob meal under conditions of a temperature of 150 to 250°C and a
pressure of 20 to 29MPa;
filtering the steamed corncob meal to obtain a filtrate from which solid has been
removed;
performing an enzyme treatment by reacting xylanase with soluble xylan in the filtrate
to hydrolyze the soluble xylan;
removing any suspended matter from a reaction product obtained during the enzyme
treatment; and
drying the reaction product
2. A process as claimed in claim 1, wherein the steaming is carried out in a pressure
vessel and the filtering is carried out by a filtering device.
3. A process as claimed in claim 1, wherein the steaming is carried out under conditions of a temperature of 180 to 200°C and a pressure of 25 to 28 Mpa.
4. A process as claimed in claim 1, wherein, in the steaming, 10 to 1000 parts by weight of water is added relative to 100 parts by weight of corncob meal.
5. A process as claimed in claim 1, wherein the steaming is carried out for 10 to 30 minutes.
6. A process as claimed in claim 1, wherein, in the steaming, a sulfurous acid compound is added to the corncob meal.
7. A process as claimed in claim 6, wherein the sulfurous acid compound is added in the amount of 1 to 10 parts by weight for 100 parts by weight of the corncob meal.
8. A process as claimed in claim 1, wherein the xylanase is added in the amount of
17

0.1 to 5 parte by weight relative to 100 parts by weight of the filtrate.
9. A process as claimed in claim 1, wherein the enzyme treatment is carried out under conditions of a pH of 3 to 8, a temperature of 30 to 50°C, a stirring speed of 60 to 200 rpm and a treatment time of 15 to 30 hours,
10. A process as claimed in claim 1, wherein
the steaming is performed by two or more sequentially connected extruders having
pressure-sealed cylinders;
the levels of temperature and pressure set rise gradually, beginning with the first
connected extruder until the last connected extruder; and
the steaming conditions for the last connected extruder satisfy the conditions of a
temperature of 150 to 250°C and a pressure of 20 to 29 Mpa.
11. A process for manufacturing xylooligosaccharides, substantially as herein described, particularly with reference to the examples.
The present invention discloses a process for manufacturing
xyloligosaccharides, comprising :
steaming a corncob meal under conditions of a temperature of 150
to 250°C and a pressure of 20 to 29MPa;
filtering the steamed corncob meal to obtain a filtrate from
which solid has been removed;
performing an enzyme treatment by reacting xylanase with soluble
xylan in the filtrate to hydrolyze the soluble xylan;
removing any suspended matter from a reaction product obtained
during the enzyme treatment; and
drying the reaction product.

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Patent Number

209418

Indian Patent Application Number

00541/KOL/2004

PG Journal Number

35/2007

Publication Date

31-Aug-2007

Grant Date

30-Aug-2007

Date of Filing

08-Sep-2004

Name of Patentee

CELJAN CO. LTD.

Applicant Address

2-5-21-401, TAKADANOBABA, SHINJUKU-KU, TOKYO, JAPAN.

Inventors:

#	Inventor's Name	Inventor's Address
1	SHUNICHI MATSUO	6-15-20-101, SHIMOMEGURO MEGURO-KU, TOKYO, JAPAN.
2	TAKATSUGU TAKAMURA	2-26-29, ASAMADAI, AGEO-SHI, SAITAMA-KEN, JAPAN

PCT International Classification Number

C08B 37/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2002-186476	2002-06-26	Japan