Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1997-05-15
1999-08-31
Wilson, James O.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536 80, 536102, 536124, 536127, 536128, C08B 3100
Patent
active
059455284
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of producing starch decomposition products having a narrow molecular weight distribution by splitting starch or starch derivatives.
Starch decomposition products, especially hydroxyethyl starch (HES), play an important role in many areas of medicine, where they are chiefly used as plasma expanders, but they are also used in dialysis (peritoneal dialysis).
In addition, starch decomposition products are administered for dietetic purposes.
2. Description of the Prior Art
Up until now, both hydrolytically decomposed as well as amylase-decomposed starches have been used to produce HES. For example, an enzymatic method is discussed in DE-C 33 13 600.
The above-mentioned chemical or biochemical methods yield products having a broad molecular weight distribution with a considerable proportion of low-molecular compounds, such as glucose, maltose or oligosaccharides; and by-products occur, for example, in the form of sodium chloride or the enzymes used in the process. These undesired components must then be removed in further process steps, e.g. by precipitation with organic solvents (acetone, isopropanol), or by ultrafiltration. On the one hand this is cost-intensive, and on the other it reduces the yield. However, such purification operations are necessary because usually the aim is to produce a product with the narrowest possible molecular weight distribution and a high degree of purity.
DE-A-41 32 701 describes such a method in which starch or starch derivatives are treated with ultrasound in an aqueous mixture (dispersions, suspensions or solutions). The purpose is to adjust the desired mean molecular weight at the desired level, as a function of the processing time and the intensity of exposure to the ultrasonic radiation, while obtaining a very narrow molecular weight distribution, in the practically total absence of undesired low-molecular components.
However, this latter method is technically very complex and in addition requires a high input of energy to split the starch.
DE-A-33-04 775 describes a method for the depolymerization of polysaccharides which can be used only for solutions of polysaccharides having a helix structure, but not for solutions of polysaccharides having a single-chain structure or an aggregated conformation. Furthermore, it has been discovered that ultrasonic depolymerization is not suitable for depolymerization of large batches on an industrial scale.
BRIEF SUMMARY OF THE INVENTION
According to WO 93/21008, starch is subjected to one or more abrupt changes in pressure in a chamber (piston device) in order to modify its physical properties. This method involves the use of a "Pascalisator" (high-pressure treatment apparatus). Only static pressure is exerted on the sample or liquid. In this method, no reduction of molecular weight is achieved. This method is therefore not suitable for obtaining a starch decomposition product with a narrow molecular weight distribution.
It is therefore the purpose of the invention to make available a method of the type described at the beginning which is technically simple and in addition requires relatively little energy to split the starch, while avoiding as far as possible the formation of undesired low-molecular starch components and while producing the highest possible yield of decomposition products.
According to the invention, this task is accomplished by using high-pressure homogenization to split the starch.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a graph showing a decrease in mean molecular weight as a function of passes
FIG. 2 is a graph showing molecular weight distribution in the case of exclusion chromatography.
DETAILED DESCRIPTION OF THE INVENTION
Compared with the ultrasonic technique, with which an expert in the field is familiar, the method according to the invention offers the advantage that the technology to be used is already widely employed for the manufacture of emulsions or dispersions and therefore is alrea
REFERENCES:
patent: 5424302 (1995-06-01), Nitsch
patent: 5455342 (1995-10-01), Redding, Jr.
Gorg Michael
Henning Klaus
Sommermeyer Klaus
Fresenius AG
Wilson James O.
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