AU724310B2

AU724310B2 - The use of an aqueous chlorite solution for disinfection in the food industry

Info

Publication number: AU724310B2
Application number: AU49478/97A
Authority: AU
Inventors: Walter Grosse-Bowing; Harald Kluschanzoff
Original assignee: Henkel Ecolab GmbH and Co KG
Current assignee: Ecolab GmbH and Co oHG
Priority date: 1996-10-24
Filing date: 1997-10-15
Publication date: 2000-09-14
Anticipated expiration: 2017-10-15
Also published as: DE19644251A1; JP2001502998A; CA2269833A1; NO991860D0; ES2158524T3; ATE202287T1; BR9712653A; CA2269833C; WO1998017326A1; EP0934084A1; DK0934084T3; AU4947897A; NZ335374A; DE59703868D1; NO991860L; EP0934084B1

Abstract

The invention concerns an aqueous chlorite solution which is used in a particularly economical process in the food industry for disinfection purposes during the cleaning of apparatus and containers, such as tanks, kegs, bottles, and pipes, which are cleaned with an acid cleaning fluid. During this cleaning step and/or a subsequent rinsing step, the chlorite solution is added to the cleaning and/or rinsing fluid.

Description

The Use of an Aqueous Chlorite Solution for Disinfection in the Food Industry This invention relates to the cleaning of equipment and containers, such as tanks, kegs, bottles and the like, and pipes in the food industry using an acidic cleaning liquid.

At the present time, tanks in the food industry are cleaned by one of the following methods.

After venting or blowing out with air, the tanks are first prerinsed. They may then be subjected to an alkaline cleaning step in which they are cleaned with 2% caustic soda solution optionally containing additives. This cleaning step, which can also be left out, is terminated by intermediate rinsing. The tanks are then cleaned for 30 to 60 minutes with an acidic cleaning liquid. The cleaning liquid used contains inorganic or organic acids. After another intermediate rinse, which lasts about 5 minutes, the tanks are disinfected for about 15 to 20 minutes. However, the tanks may also be disinfected during the acidic cleaning step, so that the last of the above-mentioned intermediate rinses and disinfection as separate cleaning steps can be left out. Finally, in a last step, the tanks are rinsed with fresh water for about 10 minutes.

Products based on monobromoacetic acid, peracetic acid, active chlorine, active oxygen, quaternary ammonium compounds (QUATS) and other compounds are used for disinfection in modern cleaning and disinfecting processes applied in the food industry. Unfortunately, none of the biocides mentioned is satisfactory in every respect. Monobromoacetic acid is highly toxic. Peracetic acid is not easy to handle and is ineffective against certain microorganisms. Active chlorine tends to form AOX and, because of this, is now rarely used. Quaternary ammonium compounds are attended by the disadvantage of a hydrophobic character.

In addition, the use of aqueous solutions of chlorine dioxide for disinfection is known from the prior art (EP 0 489 776 B1). A solution of chlorine dioxide is prepared by mixing a solution of sodium chlorite and an acidic component in a separate generator or reactor and is used immediately afterwards for disinfection. Such generators are known and are commercially available. Their disadvantage lies in the need for a separate piece of equipment for preparing the disinfecting solution.

The use of a stabilised, alkalised aqueous chlorite solution for conditioning water for drinking water purposes and also swimming pool water and for disinfecting industrial water is known from DE 34 03 631 C2. If a chlorite solution of this type is added to an aqueous system to be treated which contains chlorine or mineral acids, chlorine dioxide is mainly formed. Enzymes of the vegetable and animal metabolism present in the solution to be treated are spontaneously destroyed by chlorine dioxide. In contrast to what is said in the patent cited above, chlorine dioxide does not in fact act with high selectivity, but has an extremely broad action spectrum by comparison with other biocides.

A significant disadvantage of the known process is that the disinfecting solution to be added has to be prepared before use from at least two components, the alkaline solution and the chlorite solution, and optionally other components.

The problem addressed by the present invention was to enable disinfection to be carried out in the cleaning process mentioned above without any need for a separate reactor or to use a disinfecting solution consisting of several components.

C04496 2 It has now been found that chlorites may advantageously be used for disinfection in the cleaning of containers and equipment used in the food industry and the like. If a neutral chlorite solution containing no additional components is added to the cleaning or rinsing liquid during the acidic cleaning step and/or a subsequent rinsing step, excellent disinfection is achieved in a simple and economic manner. Where the chlorite solution is added to the rinsing liquid, a sufficiently low pH value is achieved by the acid still adhering to the equipment and containers or pipes from the preceding acidic cleaning step. Accordingly, additional acidification is not necessary. Alternatively, the chlorite solution may also be allowed to act during the last 10 minutes of the acidic cleaning step.

In the process according to the invention, it is even possible in some cases to dispense with the final rinsing step if the chlorine dioxide concentration on completion of disinfection is below 0.2ppm.

Accordingly, the present invention relates to the use of an aqueous chlorite solution in the food industry for disinfection during the cleaning of equipment and containers, such as tanks, kegs, bottles and the like, and pipes using an acidic cleaning liquid, characterised in that the chlorite solution is added to the cleaning or rinsing liquid during this cleaning step and/or a following rinsing step.

One particular advantage of the process according to the invention is that it is possible to use a neutral chlorite solution without any need for other components. The low pH value responsible for the release of chlorine dioxide is established by the acidic solution normally used in any event for cleaning.

The cleaning or rinsing liquid preferably contains 1 to 1000ppm of chlorite and, more preferably, 50 to 400ppm of chlorite.

Although a solution of sodium chlorite is preferably used, potassium salts and other salts may also be used.

So far as the action times are concerned, one particular embodiment of the invention is characterised in that the chlorite-containing cleaning or rinsing liquid is allowed to act on the containers for at least 20s and preferably for 20s to The chlorite-containing cleaning or rinsing liquid advantageously has a temperature of up to 400C and, preferably, a temperature in the range from 5 to The pH value of the chlorite-containing cleaning or rinsing liquid must be below 7 during the disinfecting step and is preferably below 5. However, there is no need for the additional introduction of acid because the pH value of the acidic cleaning liquid is sufficiently low and the rinsing liquid is sufficiently acidified by the residues from the preceding acidic cleaning step adhering to the containers or equipment or pipes.

In an alternative embodiment of the invention, an aqueous chlorite solution is used in the food industry for disinfecting equipment and containers, such as fermentation and storage tanks, in an atmosphere containing carbon dioxide. Nowadays, fermentation and storage tanks in breweries are often cleaned in a carbon dioxide atmosphere. In many cases, the cleaning solution is contaminated to such an extent that the necessary disinfection has to be carried out in a separate, following step.

According to the invention, an aqueous solution of sodium chlorite is pumped through the tanks for this purpose. The carbon dioxide present in the tank atmosphere acidifies the water so that chlorine dioxide is released. In this case, too, a solution of chlorite in water consisting of only one component CO4496 is advantageously used. The other advantage according to the invention is again achieved, namely that there is no need for a reactor to release chlorine dioxide.

Example One example of embodiment of the invention is described in detail in the following. In this case, sodium chlorite was used for disinfection during the acidic cleaning of tanks in a brewery.

In a first step, the tank was prerinsed with water for 10 minutes in order to remove the coarse soil from the inner walls of the tank. The tank was then cleaned with a 1.5% acidic cleaning solution based on phosphoric acid. After a cleaning time of about 20 minutes, 10 ppm of sodium chlorite was added to the acidic cleaning solution. The tank was then disinfected and cleaned for another minutes.

Finally, the tank was rinsed with fresh water for 10 minutes. A satisfactory cleaning and disinfection result was obtained.

Se ee o C04496

Claims

1. The use of an aqueous chlorite solution in the food industry for disinfection during the cleaning of equipment and container, using an acidic cleaning liquid, characterised in that the chlorite solution is added without pre-acidification to the cleaning or rinsing liquid during the cleaning step and/or following a rinsing step.

2. The use claimed in claim 1, characterised in that the equipment and containers are tanks, kegs, bottles and the like, and pipelines.

3. The use claimed in claim 1 or claim 2, characterised in that the cleaning or rinsing liquid contains 1 to 1000ppm of chlorite.

4. The use claimed in claim 3, characterised in that the cleaning or rinsing liquid contains to 400ppm of chlorite.

The use claimed in any one of the preceding claims, characterised in that a solution of sodium chlorite is used.

6. The use claimed in any one of the preceding claims, characterised in that the chlorite- containing cleaning or rinsing liquid is allowed to act on the containers for at least

7. The use claimed in claim 6, characterised in that the chlorite-containing cleaning or rinsing liquid is allowed to act on the containers for 20s to

8. The use claimed in any one of the preceding claims, characterised in that the chlorite- "containing cleaning or rinsing liquid has a temperature of up to °20

9. The use claimed in claim 8, characterised in that the chlorite-containing cleaning or rinsing liquid has a temperature in the range from 5 to 300C. *00:

10. The use claimed in any one of the preceding claims, characterised in that the pH value of the chlorite-containing cleaning or rinsing liquid during the disinfecting step is below 7.

11. The use claimed in any one of the preceding claims, characterised in that the pH value of the chlorite-containing cleaning or rinsing liquid during the disinfecting step is below

12. The use of an aqueous chlorite solution in the food industry for disinfecting equipment and containers in an atmosphere containing carbon dioxide, the C02 leading to acidification of the water and to the release of C10 2

13. The use claimed in claim 12, characterised in that the equipment and containers are fermentation and storage tanks.

14. The use of an aqueous chlorite solution in the food industry for disinfecting equipment and containers, substantially as hereinbefore described by reference to the Example. Dated 14 July 2000 HENKEL-ECOLAB GMBH Co. OHG Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON C04496