AU1497400A

AU1497400A - Method of disinfecting articles

Info

Publication number: AU1497400A
Application number: AU14974/00A
Authority: AU
Inventors: William Bliss
Original assignee: WOBELEA Pty Ltd
Current assignee: WOBELEA Pty Ltd
Priority date: 1999-02-09
Filing date: 2000-02-09
Publication date: 2000-08-10
Anticipated expiration: 2020-02-09
Also published as: AU772067B2

Description

Regulation 3.2 -1-

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT

S

APPLICANT: WOBELEA PTY.

NUMBER: PP 8543/99 FILING DATE: 9/ 2/1999

LIMITED

Invention Title: METHOD OF DISINFECTING ARTICLES The following statement is a full description of this invention, including the best method of performing it known to me/us: METHOD OF DISINFECTING ARTICLES This invention relates to a method of disinfecting articles, and in particular, to a method whereby disinfecting can be carried out under controlled conditions which have previously not been able to be effectively monitored.

Various applications effecting disinfection has been controlled by the use of a Redox probe or the like and, for example, where water is being treated, where it is required that there be a quantity of 2 to 15 parts per million of say chlorine at a pH of 7.5 to 8.5, such probes are perfectly satisfactory and can be used to monitor the dose of chemical being applied to the water. In this specification, for simplicity, we shall refer to chlorine in a generic sense but the system can be used with other disinfectants, such as bromine or complex compounds such as chloro-bromo compounds.

Where a hard surface, say a piece of fruit or even a wall of a building is to be sterilised it is necessary to use a very much higher concentration, say 20 to 150 parts per million.

••go It is understood that the reason for this is that it is necessary to break down a surface layer which might be a bio-film layer which is very resistant before the actual surface of the article to be sterilised can be attacked by the disinfectant.

Using a standard Redox probe or the like it is not possible to accurately determine dosages at this level, as the output of the probe tends to become constant beyond a particular quantity, say of the order of 15 to 20 parts per million and thus it is unable to differentiate between concentrations at this level and concentrations at higher levels.

There are two basic reasons why the concentration needs to be controlled. For example, if fruit is being treated, the concentration must be sufficiently high to ensure sterilisation but, at the same time, must be such that there is very little residual chemical left on the fruit which is, of course to be eaten. In addition, the use of excessive levels of chlorination or HBPs I\SPECWOBELEACAP.wpd AT 9 February, 2000 (halogen by products) may produce unacceptable levels of CPBs (chlorination by products).

While the half life of the active species such as HOBr, HOCI, C10 2 and 03 may be only minutes the life of some CPBs may be weeks and detected by analysis. It is thus essential that the residue be closely controlled.

We have found that it is possible to use a conventional method of controlling the concentration whilst the actual concentration of the other active chemicals are higher than those which are indicated by the probe, but which are nevertheless fully controlled.

The method of the invention provides disinfecting articles which uses a mixture of disinfectant materials which are in different phases, one of which phases can be monitored by S° a standard monitoring device whereby the actual application of the material in the second S phase can be very much greater than that which is indicated by the device monitoring the first phase, the proportions of the materials being such that a required effective dosage can be ascertained from the monitoring of the one phase.

In a second aspect of the invention we provide a disinfectant material in two phases as set out above but in which the material in the non-monitored phase passes through the bio-film layer prior to disassociation, providing effective sterilization in this way.

In order that the invention may be more readily understood we shall describe one embodiment of the invention.

The crux of the invention is the provision of a disinfectant which has disinfectant chemicals in two phases and in particular one of the chemicals being in the aqueous phase and the other being in an oil phase or being a dispersion of solid material in the aqueous phase which material may, if required, be encapsulated.

The disinfectant materials can be of the same species or they could be of different species but which are satisfactory for use in the particular application.

AT 9 February, 2000 4 In one preferred application which we will describe in respect of washing fruit, but this is only an exemplification, we can use chloro-bromo compound, at least in the non-aqueous phase but if required in both phases.

The disinfectant mixture is made up of known proportions of the two phases and is adapted to be added to the wash water or the like in such quantities that the liquid phase material can be monitored by a Redox probe or the like.

That is, it would normally be added to provide, say, a chlorine reading of 2 to 15 parts per million and the material in the other phase is added so that the actual total quantity of disinfectant is, say, of the order of 20 to 150 parts per million.

The Redox probe will not give an indication as far as the unassociated second phase is concerned (and for convenience in this specification I will refer to this as the 'oil phase' although as mentioned above, it does not have to be in an oil dispersion) and so the wash water being used, which may be recycled or be a one time through operation, is monitored for, say, chlorine, and is dosed to provide the required chlorine dosage as determined by the Redox probe.

o• o• Because of the mixture, however, the fruit or the like being treated is washed with water containing material in both phases and the total chlorine concentration is that which is required.

The aqueous phase tends to provide a rapid short term sterilisation whilst the oil phase tends to provide a longer term sterilisation. This can be particularly satisfactory if the product it to be exported, there can be an ongoing protection of the product and, provided the quantity of disinfectant is properly calculated, the residue will have reached a safe level at the time when the product is to be eaten.

In fact, what we have found is that it appears that the oil phase material actually neutralises K-\WP51\SPEC-\WOBELEACAP.wpd AT 9 February, 2000 the bio-film layer on the target surfaces and then dissociates within the pathogen to give a sterilising effect on the surface of the articles being treated (rather than having to first break down the bio-film layer). On evaporation of the carrier oil a film of protectant remains on the surface to provide residual protection.

It may well be that this aspect permits a lower overall concentration of the disinfectant material than would otherwise be expected, as it does appear under normal circumstances that it is the biofilm layer which prevents access to the surface of the article being treated and this is one of the reasons why higher concentrations of disinfectant may be required.

Thus, it is possible that on examination of the surface being disinfected, there could be a higher residue than is desirable or acceptable but the surface can be uncontaminated. Under these circumstances, it would only be necessary to vary the ratio between the aqueous and oil phases of the disinfectant components.

We have mentioned above that various materials can be used as the disinfectants and, in particular, the aqueous phase may include an active disinfectant from the group comprising chlorine, organo chlorine, chlorine dioxide, bromine, organo bromine, bromo chlorine, chlorind dioxide or oxygen radical.

Other compounds used could be Ca(OCl) 2 or Sodium hypochlorate and Lithium hypochlorate, BCDMH, DBDMH *1 and BCTMH 2 Di bromo di methyl hydantoin; *2 Bromo chloro tetra methyl hydantoin) Calcium oxide/hydroxide and other alkaline salts of sodium, potassium and lithium, may be combined with the above disinfectants. The ratio of alkali to disinfectant in the aqueous phase shall then nominate the range of ORP probe output.

Either phase of the disinfectant may incorporate additives such as wetting agents, dispersants, corrosion inhibitors and pH buffers.

KA\WP51\SPEC\WOBELEACAP.wpd AT 9 February, 2000 A major purpose of the invention is the use of the process in horticulture and agriculture for the control of micro organisms in the following groups.: Plant pathogens in the soil for example: Fusarium sp., Rhizoctonia, Erwinia, Phytophera, Selerotinia, Plasmodiophor.

Plant pathogens in the crop for example: Botrytis, Podosphaera, Monolinia, Venturia Anthracnose (pre-harvest) Plant pathogens in storage and transit (post harvest) for example: Rhizopus, Penicillium, Geotrichum, Mucor.

Plant pathogens occurring during a period when conventional pesticides are not applicable due to phytotoxicity, residues for example: Xanthomonas compestris Pseudomonas syringae Human pathogens occurring in the field by the use of contaminated water for spraying or irrigation (pre-harvest). The same organisms may present a health hazard when fruit and vegetables are processed, semi-processed or packed. (Post harvest). Examples of these pathogens are: coli, Staphylococcus, Pseudomonas, Listeria, B. ceres.

In each of the above examples, the aim is to combine a rapid kill in the aqueous phase with a residual in the "oil" phase.

As mentioned above, there can be other applications where the process of the invention can be used and one of these is where, for example, a clean room or the like is to be disinfected.

Whilst we have described several applications and alternatives to the compounds which can \SPEC\WOBELEACAP.wpd AT 9 February, 2000 be used with the invention, it is to be understood that there can be variations and modification of these without departing from the spirit and scope of the invention.

a a.

a a KAWP51\SPEC\WOBEl ACAP.wpdAT9Fbur,20 AT 9 February, 2000

Claims

1. A method of disinfecting articles includes using a mixture of disinfectant materials which are in different phases, one of which phases can be monitored by a standard monitoring device whereby the actual application of the material in the second phase can be very much greater than that which is indicated by the device monitoring the first phase, the proportions of the materials being such that a required effective dosage can be ascertained from the monitoring of the one phase.

2. A method as claimed in claim 1 wherein one of the materials is in the aqueous phase .•and the other an oil phase. or being a dispersion of solid material in the aqueous phase •'•"which material may, if required, be encapsulated.

3. A method as claimed in claim 1 wherein one of the materials is in the aqueous phase and the other being a dispersion of solid material in the aqueous phase. o

4. A method as claimed in claim 3 wherein the said other material is encapsulated.

5. A method as claimed in any preceding claim wherein disinfectant materials are of the same species.

6. A method as claimed in any preceding claim wherein disinfectant materials are of different species but which are satisfactory for use in the particular application.

7. A method as claimed in claim 5 or claim 6 wherein the disinfectant material in the non-aqueous phase is a chloro-bromo compound.

8. A method as claimed in claim 7 wherein the material in each phase is a chloro-bromo compound. 1\SPEC\WOBELEACAP.wpd AT 9 February, 2000

9. A method as claimed in any preceding claim wherein the disinfectant mixture is made up of known proportions of the two phases and is adapted to be added to wash water to be used to carry the disinfectant in such quantities that the liquid phase material can be monitored by a Redox probe or the like.

A method as claimed in claim 9 wherein the wash water being used, is monitored for the material in the aqueous phase and is dosed to provide the required dosage as determined by the Redox probe which will ensure that the total dosage of disinfectant material is as required.

11. A method as claimed any preceding claim in which the material in the non-monitored phase passes through a bio-film layer on the article to be disinfected prior to disassociation, thereby providing effective sterilization.

12. A method as claimed in any preceding claim wherein the material in the aqueous oeooo phase provides an immediate disinfecting of the article being disinfected whilst the .'.material in the other phase provides longer term protection. o.o

13. A method as claimed in any preceding claim wherein the articles being disinfected o• *0•"are selected from the group fruit, vegetables, crops, seeds, bulbs, corms, rhizomes and cuttings. S.

14. A method as claimed in any one of claims 1 to 12 wherein the articles being disinfected are surfaces. A method of disinfecting articles as claim in any preceding claim wherein the disinfectant materials are as described in the specification herein. 1\SPEC\WOBELEACAP.wpd AT 9 February, 2000 DATED this 9 day of February, 2000 WOBELEA PTY. LIMITED By its Patent Attorneys A TATLOCK ASSOCIATES 1\SPEC\WOBELEACAP.wpdAT9ebur,20 AT 9 February, 2000