METHOD FOR APPLYING BACTERICIDAL SOLUTIONS

METHOD FOR APPLYING BACTERICIDAL SOLUTIONS

TECHNICAL FIELD

This invention relates to a method for applying bactericidal solutions in the

bactericidal treatment of contaminated produce, apparatus and surfaces.

BACKGROUND ART

The application of bactericidal solutions in the bactericidal treatment of

contaminated produce, equipment and surfaces is usually carried out by

means of washing, with solutions such as chlorine solutions, etc. or by

means of steaming. However, total wetting during washing and/or high

temperatures during steaming are often disadvantageous in that they are

unacceptable and even detrimental to the produce, apparatus and/or

surfaces.

For purposes of this application the term "medium" shall include produce,

apparatus and surfaces and cognate terms shall have similar meanings.

OBJECTIVES OF THE INVENTION

It is accordingly an object of this invention to produce a method and

equipment for applying bactericidal solutions that will overcome the above

disadvantages. DISCLOSURE OF INVENTION

According to a first aspect of the invention there is provided a method for

applying electrochemically activated, bactericidal solution to a

contaminated medium to be treated, including the step of atomising and

dispersing the solution into the atmosphere about a contaminated medium

to be treated, forming a fog of airborne droplets of between 1 and 100

micrometers of suitable bactericidal concentration about the treated

medium.

The electrochemically activated, bactericidal aqueous solution may be

selected from a group consisting of anion-containing and cation-containing

solutions.

The electrochemically activated, bactericidal aqueous solution may be

prepared by means of electrolysis of an aqueous solution of a salt. The

salt may be sodium chloride. In particular, it may be non-iodated sodium

chloride or potassium chloride.

The anion-containing solution and the associated cation-containing solution

may be produced by an electrochemical reactor or so-called electrolysis

device having a through flow electrochemical cell with two co-axial cylindrical electrodes, with a co-axial diaphragm between the two

electrodes so as to separate an annular inter-electrode space into a

catalytic and an analytic chamber. The anion-containing solution is referred

to hereinafter for brevity as the "anolyte solution" or "anolyte" and the

cation-containing solution is referred to hereinafter for brevity as the

catholyte solution" or "catholγte".

The anolyte solution may be produced from an about 3 to 1 0% aqueous

NaCl solution, electrolysed to produce mixed reductant and mixed oxidant

species. These mixed reductant and oxidant species may be labile and

after about 96 hours the various oxidant and reductant species may

disappear with relatively no residues being produced. The anolyte solution

may have a suitable redox potential, preferably of about between + 450

mV and + 1 200 mV and may have a suitable pH, preferably of between 2

and 9 for bactericidal treatment of a specific medium. The anolyte solution

may include mixed oxidant species such as CIO; CIO ; HclO; OH ; HO₂ ^" ;

H₂O₂; O₃; S₂O₈ ^2" and CI₂O₆ ²\

The catholyte solution may have a suitable pH, preferably of between

about 1 2 and 1 3, and a suitable redox potential, preferably of between

about -200 mV and -900 mV, for bactericidal treatment of a specific medium. The catholyte solution may include reductant species such as

OH^"; H₃ ^"; 0₂; H₂-; H0₂ ; H0₂ ^" and 0₂ ^".

The method may include the preliminary step of enclosing the contaminated

medium to be treated in a closed volume prior to atomising and dispersing

the solution into the closed volume.

The atomising and dispersing step is preferably repeated at pre-determined

intervals so as to maintain a suitable fog concentration in the closed

volume, thus utilising the microcidal and other properties of the

electrochemically activated solution without detrimentally affecting the

quality and condition of the produce, such as reducing dehydration and

weight loss, the equipment and/or the surfaces to be treated.

According to a second aspect of the invention there is provided equipment

for use in a method for applying electrochemically activated, bactericidal

aqueous solution as hereinbefore defined, the equipment including an

electrolysis device having a through flow electrochemical cell with two co¬

axial cylindrical electrodes, with a co-axial diaphragm between the two

electrodes so as to separate an annular inter-electrode space into a

catalytic and an analytic chamber; and means for atomising and dispersing

the solution into the atmosphere about a contaminated medium to be treated.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of the invention will now be described by means

of non-limiting examples only.

Example 1 :

Multiple fogging cycles were used so as to determine the efficacy thereof

on the total bacterial surface loads in a series of chillers over a 42 hour

chilling period.

Samples 1 , 2 and 3 were carcasses fogged separately in closed chillers

with 30 minute intervals. Samples 4 and 5 were carcasses sampled in

operating chillers. Foggers were put on the floor of the chillers and

carcasses were therefore not fogged directly. 3 x sampling was conducted

42 hours after the previous fogging on all samples so as to establish

whether there would be an increase in bacterial loads over the 42 hours

prior to de-boning.

Multiple fogging in areas where the fog is not mechanically removed from

the room during the fogging process is highly effective in reducing total

counts. Fogging in operating chillers is not effective.

Throughout the trial Coliform counts were low, most probably due to

carcass washing and results therefore were not given. The results are

shown in the accompanying tables.

Example 2 :

Enclosed volumes containing diverse equipment, including 2 tables and a

scale, were fogged so as to determine the microcidal effect of anolyte on

the enclosure surfaces and the enclosed equipment.

The results are shown in the accompanying tables.

Example 3 :

Cattle carcasses were treated at the Agricultural Research Council Unit,

Irene, Gauteng, South Africa. The anolyte used was generated under and with the following

characteristics :

Current : 10 Ampere; Voltage : 24 Volt

ORP : + 762 mV; TDS; 6,04 g/£

pH : 6,8

The chiller treated had volume (space) for about 1 6 carcasses. The

fogging process consisted of 3 cycles of 20 minutes each, with 10 minutes

in between each cycle.

Samples were taken from the neck area, the breast area, the back area and

the hindquarter area.

Samples were taken of all micro-organisms by means of total plate count

( Redoc plates), total plate counts (petri film) and Coliforms (petri film).

The results are shown in the accompanying tables. Example 4 :

A number of 800 lamb carcasses were subjected to tests, 400 being

fogged with anolyte and 400 being used as the control group. Samples

were taken before treatment, after a second cycle and a fourth cycle, while

the control group was sampled before and after 24 hours of chilling.

Additional samples were taken from both the treated and the control group

for measuring TPC only.

The results are shown in the accompanying tables.

It will be appreciated that many variations in detail are possible without

departing from the scope and/or spirit of the invention as claimed in the

claims hereinafter.

Example 1: (New Style Pork)

Objective:

To determine the effect of multiple fogging on the total bacterial -surface loads over a 42 hour chilling period.

Comments

1, 2 and 3 were fogged separately in chillers with 30 minutes intervals.

Chillers were not in operation. After fogging, carcasses were returned to original chillers. Example 2 :

Microcidal Effect of Anolyte on Surfaces and Equipment

Example 3: (Calf Carcasses) A. Trial Carcasses Direct fogging in chiller with interrupted air circulation during the fogging process

Comments:

The fourth Swab was on the side of the triceps cut where all carcasses had been pushed by hand and were therefore more contaminated than adjoining surfaces.

All swabs were incubated at 37° C for 48 hours Coliform counts were negligible on all carcasses

B. Negative Control : Indirect fogging of carcasses that were present in the chiller, during the time of the experiment. Only final carcass counts on similar locations as the trials were taken.

Example 4:

Woolworths Trial 800 lamb carcasses

Results:

Treatment with Anolvte

Control group:

Further swabs were taken on the shoulder of 5 chilled and fogged carcases (after the 4^th fogging).

Carcase # TPC

4BS1 1

4BS2 3

4BS3 0

4BS4 6

4BS5 6

Total 16

Mean/20cm² 3.2