Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2000-05-01
2003-03-11
Fay, Zohreh (Department: 1614)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S081000, C536S102000, C536S105000, C514S778000, C127S038000
Reexamination Certificate
active
06531592
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The subject of the present invention is a process for modifying amylaceous (starchy) materials comprising stages of chemical fluidification and of stabilisation performed in the dry phase. It is also aimed at modified starchy materials obtained according to this process, certain of which materials constitute moreover novel industrial products. Finally it concerns the industrial uses of these modified starchy materials.
DETAILED DESCRIPTION OF THE INVENTION
“Chemical fluidification” is understood here to mean any operation consisting of subjecting a starchy material to the hydrolysing action of a chemical agent, for example an acid or (per)oxidant compound, it being possible to use the said agent in a liquid, solid and/or gaseous form.
“Chemical fluidification in the dry phase” is understood here to mean a chemical fluidification as defined above, carried out within a reaction mixture (including starchy material) whose moisture content is in practice less than about 25%, preferably between about 6 and 22%.
The dry phase techniques are distinguished from the methods in aqueous medium, which involve a much more dilute reaction medium using a starch milk having a dry matter content generally not exceeding 35 to 40%.
However, these fluidification methods in aqueous medium involve the use of an additional filtration stage, which has the disadvantage of causing substantial losses of soluble materials, mainly of damaged starch granules, of solubilised starch molecules and of salts formed during the prior neutralisation of the fluidified starch. This manifests itself in turn as a reduction in the yields of fluidified starchy materials and by an increase in the pollutant burden of the effluents.
These disadvantages contributed to research and the perfection of techniques for chemical fluidification in the dry phase. Thus the patents U.S. Pat. Nos. 3,479,220 and 3,692,581 describe a process for the chemical fluidification of starchy materials (starch flours, meals) by contacting these materials, at ambient temperature (≈25° C.), with a concentrated inorganic acid placed on a finely divided dry, inert support.
EP Patent 710.670 describes a continuous chemical modification process according to which a starch powder and a modifying agent, for example a hydrolysing agent such as hydrochloric acid, are introduced simultaneously into a special reactor (“turbo-reactor”) whose spiral enables the creation by centrifugation, semi-instantaneously, of a fine, dynamic and highly turbulent liquid layer of an intimate mixture between the particles of starch and the chemical agent.
The patent application WO 97/13788 describes in general terms a process for the chemical fluidification of starches carried out continuously in the dry phase involving the mandatory use of, among other things, a reactor of the piston type (“plug flow reactor”) and of reaction temperatures at most equal to 77° C. (170° F.).
This patent recommends a very wide range of chemical agents with hydrolysing activity, the preferred agents being hydrochloric acid, particularly in the gaseous form, and sulphuric acid. However, this document does not actually describe any specific example of the preparation of a fluidified starch.
In any case, whether they are operated in an aqueous medium or in the dry phase, chemical fluidification techniques enable the preparation of modified products displaying commonly sought-after physico-chemical properties such as:
a reduced intrinsic viscosity and hot viscosity, the hot viscosity being evaluated by the classical measurement of the fluidity in water (“Water Fluidity” or WF),
an increased hot solubility, and
an increased gel strength (“gel strength”) and film-forming ability (“film strength”).
One of the main techno-economic advantages of chemically fluidified starchy materials consists of their ability to be used and treated, particularly to be cooked, to materials with a very high matter content.
This is because of the fact that their viscosity is greatly reduced compared to the native products. This ability manifests itself as energy savings (smaller volumes of water to be removed) and technological benefits that are widely turned to good account in industry. Nonetheless, whatever their production process, chemically fluidified starchy materials generally have the disadvantage that they form sizes that are not very stable, and particularly sizes that show a very significant increase in viscosity when cooled down and/or when stored for a prolonged time. This instability often manifests itself in an irreversible phenomenon of gelatinization or retrogradation.
This is the reason why chemical fluidification techniques are generally associated with stabilisation reactions, particularly with esterification, etherification or oxidation reactions, in order to make the fluidified starchy materials usable industrially. This may involve in particular reactions of acetylation, hydroxypropylation or oxidation by hypochlorite solution. Although these techniques are effective, they have the disadvantage of forming a large amount of organic and/or saline pollution. Other methods are aimed at combining the chemical fluidification techniques with cross-linking reactions.
Thus U.S. Pat. No. 3,705,046 describes the cross-linking, in the aqueous phase, of a starch, native or cationic, by the use of paraformaldehyde, this being done at the same time as or after its fluidification by hydrochloric acid. The crosslinked/fluidified starch obtained is said to have very good stability and can be used advantageously for coating textile or papermaking fibres.
U.S. Pat. No. 3,661,895 describes the preparation, for the same purposes, of a starch that is successively fluidified, cross-linked and then treated with a polycarboxylic acid anhydride, all of the operations being carried out in aqueous medium.
The U.S. Pat. Nos. 3,778,431 and 3,884,909 describe the cross-linking, in the aqueous phase, of a native or cationic maize starch by the use of a cross-linking agent such as 1,3-dichloro-2-propanol, 1,4-dichlorobutene-2 or epichlorhydrin, this being done following its fluidification by hydrochloric acid, again in aqueous medium.
However, such processes have or indeed exacerbate the above-mentioned disadvantages that are inherent with processes in the aqueous phase (reduction of yields, increase of pollutant burdens). These processes also have the disadvantage of being complicated and in particular of involving the use of two different agents, namely one fluidification agent and one cross-linking agent, this generally taking place during two different stages, themselves separated by intermediate treatments.
For their part, the much more recent patents EP 710.670 and WO 97/13788 mentioned above are not concerned specifically with combining a fluidification stage with a cross-linking stage, except that document WO 97/13788 mentions, in a manner not described in detail, the possibility that the starch subjected to the fluidification (“starch source”) had previously been modified by agents such as epichlorhydrin or phosphorus oxychloride (cf. page 3, lines 9-25 of the aforesaid document).
DETAILED DESCRIPTION OF THE INVENTION
It emerges from the foregoing that to the Applicant's knowledge there does not exist any means of preparing a fluidified and stabilised starchy material, namely a means that simultaneously:
is simple and particularly does not involve the compulsory use of several agents and/or of several stages of chemical modification,
allows the industrial production of products having good stability to cooling and/or during prolonged storage,
is applicable to starchy materials of very varied nature or intended to be subjected afterwards to very varied chemical or physical modifications,
is economical and in particular allows the achievement of good yields of fluidified starchy materials, and
produces little pollutant or none at all, and in particular does not cause substantial losses of soluble materials into effluents.
Applicants have discovered, after numerous studies, that s
Dreux Jean-Louis
Fuertes Patrick
Lambin Anne
Fay Zohreh
Kwon Brian-Yong
Roquette Freres
Sturm & Fix LLP
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