Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing compound containing saccharide radical
Reexamination Certificate
1996-10-28
2001-05-15
Prats, Francisco (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing compound containing saccharide radical
C435S101000, C435S099000, C435S274000, C435S275000, C536S123100, C536S126000, C536S128000, C514S054000, C424S488000
Reexamination Certificate
active
06232101
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for causing gelling or increase of viscosity of aqueous media containing gellable polymeric materials having substituents with phenolic hydroxy groups.
BACKGROUND OF THE INVENTION
Certain pectins, e.g. pectin from sugar beets and pectin from spinach, as well as hemicellulosic material from certain cereals, e.g. from wheat and maize, are substituted to some extent with substituents derived from certain carboxylic acids (normally substituted cinnamic acids) containing phenolic hydroxy groups. Substances of this type are, for convenience and brevity, often referred to in the following simply as “phenolic polysaccharides”.
A number of naturally occurring phenolic polysaccharides of the above-mentioned type are readily available relatively cheaply and are of proven physiological safety with regard to ingestion by, and contact with, humans and animals. Such phenolic polysaccharides have numerous applications relating to their ability to undergo gelling or viscosity increase under certain conditions. Areas of application of the resulting gelled or viscous products include, but are by no means limited to, the following:
Foodstuff applications: as a thickening and/or stabilising agent in sauces, gravy, desserts, toppings, ice cream and the like; as a setting agent in marmelades, jams, gellies and the like; as a viscosity-regulating agent in flavouring extracts and the like.
Medical/medicinal applications: as a material for drug encapsulation; as a slow release vehicle for drug delivery (e.g. oral, anal or vaginal); as a material for a wound or burn dressing.
Agricultural/horticultural applications: as a slow release vehicle for pesticide delivery (i.e. as a biocontainer); as a plant culture medium.
Oxidative cross-linking of phenolic polysaccharides of plant origin (with resultant gelling) is described in, e.g., FR 2 545 101 and WO 93/10158, and by J. -F. Thibault et al. in
The Chemistry and Technology of Pectin
, Academic Press 1991, Chapter 7, pp. 119-133.
The cross-linking of phenolic polysaccharides may be achieved by purely chemical modification using a powerful oxidant such as, e.g, persulfate [as described in J. -F. Thibault et al. (vide supra) in connection with the gelling of beet pectins].
With respect to enzyme-catalyzed processes, J. -F. Thibault et al. (vide supra) also describe the gelling of beet pectins using a combination of a peroxidase and hydrogen peroxide. Similarly, WO 93/10158 describes gelling of aqueous hemicellulosic material containing phenolic substituents (e.g. substituents derived from “ferulic acid” (i.e. 4-hydroxy-3-methoxycinnamic acid; it does not appear to have been established clearly whether “ferulic acid” embraces cis or trans isomeric forms, or both) using an oxidizing system comprising a peroxide (such as hydrogen peroxide) and an “oxygenase” (preferably a peroxidase).
FR 2 545 101 A1 describes a process for modification (including gelling) of beet pectin involving the use of “an oxidizing system comprising at least an oxidizing agent and an enzyme for which the oxidizing agent in question is a substrate”. However, the only types of oxidizing agent and enzyme which are specified and/or for which working examples are given are hydrogen peroxide and peroxidases, respectively.
The documents outlined briefly above describe, inter alia, the use of the resulting modified/gelled materials for medical/medicinal purposes, in cosmetics and/or in foodstuffs. However, neither peroxide treatment nor chemical modification of substances intended for ingestion (e.g. substances for use in foodstuffs) or for uses which may result in more or less prolonged contact with, or close proximity to, skin or mucous membranes are desirable, and such treatments are in fact not permitted in many countries. As will be apparent from the above discussion, there seems to be a lack of real awareness of the possibility of avoiding such undesirable treatments, and it is an object of the present invention to provide an alternative to the existing methods.
SUMMARY OF THE INVENTION
It has now surprisingly been found that gelling or increase in viscosity of aqueous, gellable polymeric materials having substituents with phenolic hydroxy groups, notably phenolic polysaccharides, may be achieved very satisfactorily via the simple addition of an appropriate amount of an enzyme of the oxidase type (vide infra), especially a laccase. Laccases utilize oxygen—very suitably oxygen from the atmosphere—as oxidizing agent, and the use of undesirable reagents such as peroxides may thus be eliminated with the process of the present invention.
Laccases are less powerful oxidation-promotors than, e.g., peroxidases, and it is thus surprising that gelling and/or viscosity increase according to the invention can be achieved in the absence of a powerfully oxidizing peroxide reagent. As mentioned above, laccase-catalyzed oxidation involves oxygen, and the consumption of oxygen in the process of the invention leads to the possibility of exploiting the process in a manner which can be advantageous from the point of view of increasing the shelf-life of, e.g., foodstuffs or medicinal products in the preparation of which the process of the invention is employed, since the consumption of oxygen initially present in a sealed foodstuffs package or the like will reduce the possibility of oxidative degradation of the packaged contents.
REFERENCES:
patent: 4672034 (1987-06-01), Rombouts et al.
patent: 5346695 (1994-09-01), Nonoyama et al.
patent: 2 261 671 (1993-05-01), None
patent: WO 93/10158 (1993-05-01), None
patent: 9312259 (1993-06-01), None
patent: WO 96/03440 (1996-02-01), None
Thibault et al, Carb. Res. 154:205-215 (1986).*
J.F. Thibault et al., “Gelation of Sugar Beet Pectin By Oxidative Coupling”, The Chemistry and Technology of Pectin, 1991, pp. 119-133.
Kennedy et al., Elsevier Applied Science, vol. 12, (1990), pp. 353-374.
Budolfsen Gitte
Heldt-Hansen Hans Peter
Garbell Esq. Jason I.
Lambiris Esq. Elias J.
Novozymes A/S Patents
Prats Francisco
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