Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Process of storage or protection
Patent
1998-01-06
2000-09-26
McKane, Elizabeth
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Process of storage or protection
422 29, 423219, B01J 1900
Patent
active
061239011
DESCRIPTION:
BRIEF SUMMARY
This invention relates to methods and materials for reducing the oxygen concentration present in an atmosphere, solid, semi-solid or liquid (often referred to as oxygen scavenging).
A wide variety of foods and other materials are susceptible to loss in quality during storage under atmospheric levels of oxygen. The damage can arise from chemical oxidation of the product, from microbial growth, and from attack by vermin--much of which may be avoided by reducing the oxygen availability in the environment of the materials. In the field of packaging, relatively low-oxygen atmospheres have traditionally been generated by vacuum packaging and inert gas flushing. However, chemical techniques for generating low-oxygen atmospheres and deoxygenating liquid or semi-liquid foods have also been proposed (see, for example U.S. Pat. No. 5,211,875 and our co-pending application No PCT/AU93/00598 published as WO 94/12590). The disclosure of both of these patent specifications is to be considered as incorporated herein by reference.
The compositions and packaging materials described in WO 94/12590 may be activated to their oxygen scavenging form when it is most convenient or desirable. This means that activation may be carried out just prior to application and thereby avoids the necessity of storing the activated composition or packaging material in an inert atmosphere or vacuum. However, there are situations and applications where it would be preferred to activate the composition or packaging material at a site remote from where the composition/package is to be used.
Thus, in a first aspect the present invention provides an oxygen scavenging material comprising at least one compound oxidizable by molecular oxygen, wherein said at least one compound is contained within an oxygen impermeable compartment(s) or microcapsule(s) which may, as required, be broken or otherwise rendered oxygen permeable by application of heat, electromagnetic radiation, mechanical pressure or stress, or by hydration.
The at least one compound oxidizable by molecular oxygen may be any of those described in WO 94/12590. However, it is preferred that the at least one oxidizable compound is a compound produced from the photoreduction of an oxidized precursor compound and is oxidizable under conditions independent of both constant illumination and the presence of a transition metal catalyst. More preferably, the at least one oxidizable compound is selected from the group consisting of the reduced forms of quinones, such as benzoquinone, anthraquinone (e.g. 9,10-anthraquinone) and napthoquinone (e.g. 1,4-napthoquinone); photoreducible dyes (e.g. methylene blue); and carbonyl compounds which have absorbance in the UV spectrum, such as azo, thiazine, indigoid and triarylmethane compounds. However, iron powder and oxidisable MXD-6 nylon or 1,2-polybutadiene in the presence of a transition metal salt catalyst, may also be suitable.
Most preferably, the at least one oxidizable compound is a reduced form of a substituted anthraquinone such as 2-methylanthraquinone, 2-ethylanthraquinone and 2-amylanthraquinone.
In some applications of the invention, particularly food packaging, it is also preferred that the at least one oxidation compound be present in a polymerised or oligomerised form. The preparation of oxidized polymeric and oligomeric precursor compounds is described in WO 94/12590.
The at least one oxidizable compound may be used in substantially pure form, however, it is preferred that it be present as a component of a composition according to the invention described in WO 94/12590.
Where the at least one oxidizable compound is present as a component of a composition, the composition may further comprise an activated oxygen scavenging component reactive to activated oxygen species (e.g. peroxide) which may be generated during the scavenging of molecular oxygen. Preferred examples of the activated oxygen scavenging component include antioxidants such as alkylated phenols and bisphenols, alkylidene bis-, tris- and polyphenols, thio- and bis-, tris- and poly
REFERENCES:
patent: 4510162 (1985-04-01), Nezat
patent: 4898734 (1990-02-01), Mathiowitz et al.
patent: 5262375 (1993-11-01), McKedy
patent: 5286407 (1994-02-01), Inoue et al.
patent: 5366881 (1994-11-01), Singh et al.
Albert Candiera Faith
Rooney Michael Laurence
McKane Elizabeth
The Commonwealth of Australia Commonwealth Scientific and Indust
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