Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2001-02-26
2004-03-23
Spivack, Phyllis G. (Department: 1614)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C435S099000
Reexamination Certificate
active
06710176
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing water-soluble polysaccharides, and to a method for clarifying water-soluble polysaccharide aqueous solutions and, more specifically, it relates to a process for efficiently and conveniently producing and clarifying water-soluble polysaccharides derived from legumes, which gives visible transparency and clarity with no turbidity or precipitate production even after long-term storage or cold storage of aqueous solutions of the extracted water-soluble polysaccharides, and which results in a lower degree of browning or moisture absorption with long-term storage.
2. Description of the Related Art
The present inventors have already filed Japanese Patent Application No. 2-30677 (Japanese Unexamined Patent Publication No. 3-236759) based on the discovery that when extracting water-soluble polysaccharides from legumes such as soybeans or green peas which contain abundant protein components, extraction at a pH near the isoelectric point of the protein components contained in the legumes hampers elution of the abundantly present protein components in the legumes, thus facilitating the subsequent purification step.
The present inventions have also already filed Japanese Patent Application No. 5-329214 (Japanese Unexamined Patent Publication No. 7-188301) for a method of hydrolyzing and solubilizing the suspended protein components for the purpose of improving the clarity of the water-soluble polysaccharides obtained by the aforementioned method, and Japanese Patent Application No. 10-43756 (Japanese Unexamined Patent Publication No. 11-240902) for a method of promoting production of, and removing, the suspended matter by concentration during the production steps. The aqueous solutions of water-soluble polysaccharides prepared by these methods have dramatically improved clarity, but a problem has remained in that the water-soluble polysaccharides dissolve in the aqueous solutions, and water-insoluble suspended substances or precipitates are produced with long-term storage or cold storage.
These suspended substances or precipitates have been very difficult to remove industrially because they are produced after long-term storage or cold storage. In particular, when a water-soluble polysaccharide is cooled after preparation or the water-soluble polysaccharide is heated to form an aqueous solution and then placed in cold storage, the resulting colloidal suspended substances have been difficult to remove, and the colloidal suspended substances have been a cause of clogging of filters or columns in the UF apparatuses or the like which are used in a cooled state during production of the water-soluble polysaccharide.
As means for solving this problem there have been known, in addition to the method of protein component hydrolysis of the aforementioned prior application, also precipitation and removal of suspended substances using a centrifugal separator with a high centrifugal force, and removal of suspended substances and precipitates using filters with small pore sizes or filter aids such as diatomaceous earth. When high centrifugal force is used, however, the high cost of the equipment poses a problem in terms of production. When various filters are used, the high viscosity of the suspended substances has tended to result in clogging which prevents any extended treatment. Thus, it has been difficult to efficiently remove peptide components that are products of low molecular weight conversion with proteases and cause browning or moisture absorption after drying, and such browning has therefore not been preventable.
The water-insoluble suspended substances or precipitates produced after storage of water-soluble polysaccharides obtained by extraction from legumes in the manner described above are believed to consist mostly of insoluble protein components, insoluble salts and portions of the micronized starting material, while the sugar components in particular are believed to consist of difficult-to-separate hemicelluloses and celluloses. It is therefore thought that hydrolysis of these polysaccharide components with enzymes such as hemicellulases and cellulases results in hydrolysis of the useful water-soluble polysaccharide components as well, making it impossible to obtain the desired water-soluble polysaccharides.
In the case of legumes that contain abundant amounts of starch components, such as green peas and red beans, the possibility of elution of the starch components into the extracted water-soluble polysaccharide fraction had been amply considered, but in the case of soybeans which are a more useful source for water-soluble polysaccharide extraction, the starch component content in mature soybeans is considered to be very low, and therefore the starch components in the extracted water-soluble polysaccharides have not received much attention nor been studied.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to efficiently produce water-soluble polysaccharides whose aqueous solutions have low turbidity and little production of suspended substances or precipitates even during long-term storage or cold storage, and which exhibit minimal browning and moisture absorption during long-term storage, by a convenient method and from legumes.
As a result of diligent research in light of the circumstances described above, the present inventors have found that a relatively large amount of starch components are present in addition to protein components in the suspended matter produced when extracting and purifying water-soluble polysaccharides from legumes, or when storing water-soluble polysaccharide aqueous solutions after purification. That is, it was found that, even when the starting materials are soybeans, such water-soluble polysaccharide aqueous solutions extracted from the legumes exhibit a violet coloring reaction with iodine solutions which indicates the presence of starch components, and it was conjectured that the suspended substances or precipitates produced upon long-term storage or cold storage of the aqueous solutions are the starch components insolubilized by aging. When such water-soluble polysaccharide aqueous solutions were treated with amylases for hydrolysis of the starch components, it was found that the clarity of the water-soluble polysaccharide aqueous solutions not only improves upon cooling after production, but that production of precipitates during long-term storage and production of suspended substances during cold storage can be prevented. In addition, it was discovered that water-soluble polysaccharides that have been thus treated with amylases cause little clogging of filters used for ultrafiltration (UF) or microfiltration (MF), or membranes of small pore size such as semipermeable membranes and reverse osmosis (RO) membranes, and that when such high efficiency low molecular component removal apparatuses are used in the production of water-soluble polysaccharides, it is possible to more easily produce water-soluble polysaccharides with minimal browning and moisture absorption during storage. The present invention has been completed on the basis of these discoveries.
In other words, the present invention relates to a process for producing water-soluble polysaccharides, which comprises allowing an amylase to act on a water-soluble polysaccharide extract derived from a legume and removing the insoluble matter, and to a method for clarifying a water-soluble polysaccharide aqueous solution, which comprises allowing an amylase to act on a water-soluble polysaccharide extract derived from a legume and removing the insoluble matter.
DETAILED DESCRIPTION OF THE INVENTION
The legumes as used in the invention may be any of various legumes including butter beans, red beans, kidney beans, peas, green peas, cowpeas, horse-beans, soybeans, swordbeans, peanuts, lupins, chick peas, Egyptian kidney beans, mung beans, vetch beans and lentils, as well as various nuts including cashew nuts and the like. When the starting material is soybeans, it may be th
Furuta Hitoshi
Kiwata Ryosuke
Maeda Hirokazu
Nakamura Akihiro
Takahashi Taro
Delacroix-Muirheid C.
Fuji Oil Co., LTD
Paul & Paul
Spivack Phyllis G.
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