AU5630199A

AU5630199A - Solution useful for bacterial decontamination of foodstuffs and method for using same

Info

Publication number: AU5630199A
Application number: AU56301/99A
Authority: AU
Inventors: Sophie Vincent
Original assignee: Rhodia Chimie SAS
Current assignee: Rhodia Chimie SAS
Priority date: 1998-09-25
Filing date: 1999-09-20
Publication date: 2000-04-17
Anticipated expiration: 2019-09-20
Also published as: EP1115294B1; FR2783675B1; ATE238677T1; CA2344240A1; EP1115294A1; ZA200101854B; FR2783675A1; AU752652B2; DE69907487D1; BR9913940A; WO2000018246A1

Abstract

The invention concerns a method for treating foods characterised in that it comprises a step which consists in contacting said food with a solution having an OH-concentration ranging between 0.02 and 0.2 and in that said solution further comprises a tribasic salt of orthophosphoric acid such that the ratio of the initial OH-ion concentration, expressed in equivalent per litre, to the orthophosphate concentration is not less than 1/4, advantageously 1/3. The invention is useful for bacterial decontamination of foodstuffs.

Description

WO 00/18246 PCT/FR99/02226 1 SOLUTION WHICH IS USEFUL FOR THE BACTERIAL DECONTAMINATION OF FOODSTUFFS AND PROCESS FOR USING IT The present invention relates to aqueous 5 solutions which are useful for the bacterial decontamination of foodstuffs. The invention relates more particularly to weakly concentrated solutions containing both a basic compound and a tribasic phosphate. 10 The bacterial contamination of foodstuffs is a problem which is of more and more increasing concern to the authorities and companies distributing foodstuffs. The reason for this is that bacterial contamination causes an impairment of foods and can 15 lead to serious poisoning of the end consumer; whether this poisoning is a direct poisoning when the food is eaten uncooked without destruction of the microbial flora, or whether this food is contaminated with toxins released by the bacteria, during their lifetime or when 20 they die. The problem is particularly acute in the case of animal productions. Many processes for decontaminating animal foodstuffs have already been proposed. However, only a 25 few have a balance between their cost and the efficacy WO 00/18246 PCT/FR99/02226 2 which would allow them to be used on an industrial scale. Specifically, the problem is complex since, on the one hand, the surface of the foodstuff should be 5 decontaminated, and, on the other hand, subsequent recontamination should be avoided, either during the treatment or in the course of a subsequent or prior rinsing operation. Moreover, the efficacy of the decontamination 10 should be extremely rapid; failing this, the treatments cannot be carried out on an industrial scale since they would involve considerable treatment volumes. In addition, when the treatment is directed towards the carcasses of land animals and uses an 15 aqueous phase, a prolonged contact runs the risk of being problematic and may lead to a gain in weight by incorporation of water into the foodstuffs treated by the process, this gain in weight being regulated in many countries. 20 The problem of contamination is particularly acute in foods or foodstuffs which have not undergone any preparation, and/or which have not been cooked. Mention may thus be made of plant productions directly after harvesting and animal foodstuffs immediately 25 after fishing or slaughtering. 0 WO 00/18246 PCT/FR99/02226 3 Thus, products which may be treated include the carcasses of dead animals a short time after the animals have been slaughtered for consumption. Without wishing to be limiting hereby, 5 mention may be made of the carcasses of quadrupeds, in particular of bovids such as bovines (for example buffaloes, aurochs and bison), antelopes, ovines, caprines (including game such as stags, chamois, deer, elks, moose, izards and roe deer), suids (for example 10 pigs, boars and peccaries), lagomorphs (such as rabbits, hares and agoutis) as well as the carcasses of fowl, among which mention may be made of all wild and/or rearing fowl, from the smallest (for example trogons and larks) to ratites (for example ostriches), 15 in particular including passerines (for example thrushes), gallinaceans (for example hens, quails, guinea fowl, partridges, turkeys and grouse) and anatids (for example ducks, geese and teals). The treatment may also apply to reptiles and 20 fish. The carcasses may be treated before, but advantageously after skinning. In the case of birds, it is desirable for this treatment to be carried out after plucking. 25 One of the most awkward problems in the treatment of animal carcasses lies in the fact that ETj{ WO 00/18246 PCT/FR99/02226 4 these carcasses must often be washed with large amounts of water and that this water is often the vector for transferring a contamination from one particular carcass to all of the carcasses. 5 One of the solutions recommended to date is the use of bleach at concentrations of about several hundred PPM, in general at about 600 to 800 PPM. However, some scientists consider that the use of bleach for treating carcasses may involve a risk 10 of cancer when the bleach concentrations are high and in particular when they are higher than 500 PPM of chlorine. Accordingly, one of aims of the present invention is to provide a technique which is capable of 15 preventing [lacuna] the waters for washing and rinsing animal carcasses, without this involving the use of a content of greater than 500 PPM of chlorine contained, preferably not greater than 200 PPM and more preferentially not greater than 100 PPM. 20 Another aim of the present invention is to provide a process which makes it possible to obtain a decontamination of washing and rinsing waters using waters containing little mineral material, preferably not more than 2% by mass. 25 These aims and others which will become apparent hereinbelow are achieved by means of a process WO 00/18246 PCT/FR99/02226 5 for treating foods which comprises a step of placing the said food in contact with a solution having an OH~ concentration of between 0.02 and 0.2 N (equivalent per litre) and by the fact that a tribasic salt of ortho 5 phosphoric acid is added thereto such that the ratio between the initial concentration of OH- ions and the concentration of orthophosphates, expressed as equivalents, is at least equal to 1/4, advantageously to 1/3, preferably to 1/2 and more preferentially to 1. 10 It is advantageous for the content of ortho phosphorate species to be at least equal to 0.01 M and not more than 0.1 M. The initial content of OH~ ions is advantageously at least equal to 0.05 M. 15 The expression "initial concentration of OH ions" means the concentration of OH ions of the solution without the tribasic salt of orthophosphoric acid. In other words, it is thus the concentration 20 of OH- ions which is obtained in the absence of the tribasic salt of phosphoric acid, more generally in the absence of any phosphate. This value of the OH- ions may be readily measured by techniques that are well known to those skilled in the art by means of a pH meter with 25 electrodes adapted to the type of medium and to the pH WO 00/18246 PCT/FR99/02226 6 range under consideration, i.e. to the range between about 12 and about 13. The values are given for a temperature of 25OC and at atmospheric pressure. 5 Given the inherent risk of denaturing the food when a very basic solution is used, it is preferable to use solutions with an initial content of OH- ions of not more than 0.1 N (corresponding at 250C to a pH of 13). 10 It is also preferable for the content of phosphate ions in the solution to be not more than 0.1 N, so as to prevent the solution from being overloaded with mineral elements. In order to obtain a significant synergistic 15 effect between the OH- ions and the phosphate species, it is preferable for the latter species to be present at a concentration at least equal to 0.02 M. The OH ions are advantageously in the form of alkali metal hydroxides, ammonium hydroxides or quaternary 20 phosphonium hydroxides, or in the form of hydroxide(s) of cation(s) masked by complexation (essentially complexing agents that are neutral complexers or sequestering agents, such as, for example, crown ethers). 25 However, given the enormous amounts to be treated and the price of the latter compounds, it is (IRA4 WO 00/18246 PCT/FR99/02226 7 preferable for the cations associated both with the hydroxide ion and with the P0 4 3 - ion to be alkali metals or mixtures of various alkali metals. Lithium is not preferred, far from it, for this application, the most 5 effective being potassium, rubidium and caesium, a good compromise lying in the use of the sodium or potassium ion and mixtures thereof. Although rubidium and caesium give excellent results, they are far too expensive for this type of application. 10 The OH- ions may be introduced by any means known to those skilled in the art, whether in the form of salts of very weak acids, or by reaction of precipitable compounds (for example a successive mixture of trisodium phosphate combined with a calcium 15 hydroxide thus precipitating phosphate and leading to the formation of sodium hydroxide in situ). Products such as oxylith (Na 2 0 2 ) which may give rise to sodium hydroxide and hydrogen peroxide, which will reinforce the action of the anti 20 contaminating system may also be used, and under basic conditions which give the hydrogen peroxide an extremely short lifetime. It may also be envisaged to introduce the OH ions in the form of alkoxides which will produce, by 25 action on water, a hydroxide and an alcohol, which may be evaporated off during the treatment.

WO 00/18246 PCT/FR99/02226 8 Up to a content of about 5%, the alcohol does not modify the properties of the solution. However, it is simpler to introduce the hydroxide ions in the form of alkali metal 5 hydroxide(s), but also alkali metals or a mixture of alkali metal phosphates. The solution targeted by the present invention is particularly suitable for rinsing and may be used, for example, before or after another treatment 10 for decontamination of foodstuffs per se. It may be used more specifically to prevent contamination after a step of contamination, for example in the system denoted as a "tank chiller", i.e. in a system of cooling in a tank of water at high flow rate. 15 The solution according to the present invention can also be used for decontamination, by simply adapting the contact time. However, when the content of mineral ions is low, prolonging the contact time runs the risk of being problematic and may lead to 20 a gain in weight by incorporating water into the foodstuff treated by the process, this gain in weight being regulated in many countries. The decontaminating system has the advantage of being compatible with many other decontaminating 25 systems, whether organic or mineral.

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WO 00/18246 PCT/FR99/02226 9 The effect of the solutions according to the invention may be reinforced with oxidizing agents; among these, mention may definitely be made of permanganates and dichromates, but the latter are 5 colored and may under certain conditions lead to precipitates, which may introduce a problem into the process. Thus, oxidizing agents containing ozone and/or hydrogen peroxide, or even hypochlorites, are preferred. 10 From the point of view of the efficacy of the treatment, it is desirable for the oxidizing power of the solution to be at least equal to 0.001 N, advantageously equal to 0.002 N and preferably equal to 0.005 N (electron equivalents per litre). However, the 15 concentration of these agents should be limited as much as possible, since they do not always have a good reputation. Thus, one of the best agents would be ozone, if not for its cost. Otherwise, in the event of potentiating the solutions according to the invention 20 with oxidizing agents, it is recommended to limit the oxidizing power to 0.05 N, advantageously to 0.02 N and preferably to 0.01 N. The hypochlorite effect is reinforced by the system according to the present invention, which makes 25 it possible to use low concentrations, generally concentrations of less than 500 PPM (as mass of T s T

I

WO 00/18246 PCT/FR99/02226 10 chlorine C1 2 r lative to the mass of treating solution), more generally less than 200 PPM, and it is even possible to observe an effect between the two systems at concentrations of chlorine contained of less than 5 100 PPM. Other elements, such as carbonates, may also be added to the solution, provided that this does not alter the init al basicity. Thus, the main use of this solution is for 10 placing in contact with the foodstuff to be treated, this placing ir contact usually being carried out by dipping, spray ng or misting. It is desirable for the dipping, spraying or misting time to be not more than 1/2 hour, advantageously not more than 1/5 hour and 15 preferably not more than 1/10 hour. It is at least 1 second, advantageously 10 seconds and preferably 20 seconds. The contact may be partially continued after the dipping, spraying or misting, if there is no rinsing operation. 20 This placing in contact may be carried out at a temperature at least equal to 0 0 C, advantageously at about 100C, preferably at 20 0 C. In the present description, the term "about" is used to emphasize the fact that the values which follow it correspond to 25 mathematical round-ups and in particular that when the figure(s) furthest to the right of a number is (are) r STIRe WO 00/18246 PCT/FR99/02226 11 zeroes, these zeroes are positional zeroes rather than significant figures, except, of course, unless otherwise specified. It is preferable, in order to prevent the 5 foods from being impaired, not to exceed the temperatures which modify the structure of the food. As regards carcasses and foodstuffs of animal origin that are untreated, this placing in contact may be carried out at a temperature equal to 80 0 C and advantageously 10 equal to 700C. The pressure has very little influence on the process according to the present invention at atmospheric pressure or at a pressure thereabout, and at any altitude. 15 As has already been mentioned, the foodstuff to be treated is advantageously an animal foodstuff, whether this is carcasses or carcasses after cutting up, but the results may be obtained on other products such as, for example, eggs. This decontamination system 20 also functions very well for compounds which are intended for freezing. The non-limiting examples which follow illustrate the invention. Example 25 Measurement of the effect of TSP (0.4%) in the presence of different concentrations of NaOH on

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WO 00/18246 PCT/FR99/02226 12 Salmonella tyhpimurium IPL and Escherichia coli NIJH-JC2. B.1 Principle 5 B.1.1. Culturing A brain heart infusion (BHI) conical flask (10 ml) was inoculated with a colony of Salmonella typhimurium IPL or of E. coli NIJH-JC2, and then placed at 37 0 C on 10 a shaker table. After 18 h, the bacterial count was, respectively, ~ 6 x 109 and 7 x 109 colony forming units per milliliter (CFU/ml). After diluting 500-fold with BHI culture medium, the bacterial count was 15 1 x 107 CFU/ml. This diluted culture was then used for the rest of the experiment. B.1.2. Samples The various mixtures of TSP and NaOH were prepared beforehand, such that the 20 concentrations obtained in these mixtures are twice that of the final concentrations tested. Thus, for example, the TSP had a concentration of 0.8%. At t:0 min, 0.5 ml of bacteria 25 (diluted 500-fold) was added to 0.5 ml of the different mixtures and left in contact for 7T WO 00/18246 PCT/FR99/02226 13 30 s. 100 pl were taken and then serially diluted (10-fold) in sterile distilled water containing NaCl (9 g/l). 100 pl of each dilution were spread on a Petri dish (BHI + 5 1.5% agar-agar). For certain samples, 100 pl were spread directly on the dish without being diluted. The dishes were incubated for 18 h at 370C. The colonies present on the dishes were counted and the 10 number of CFU (colony-forming units)/ml deduced. B.2 Results CFU/ml Samples S. typhimurium E. coli Control 7.00 x 106 2.01 x 106 Control (1) 1.20 x 107 2.08 x 106 TSP (0.4%) 4.86 x 106 4.06 x 106 TSP (0.4%) + NaOH (3.1) 1.106 2.105 TSP + NaOH (3.2) 5.02 x 104 2.25 x 104 TSP + NaOH (3.3) 5.02 x 104 5.54 X 104 TSP + NaOH (3.35) 5.00 x 104 4.32 x 10' TSP + NaOH (3.4) 5.02 X 104 1.52 X 104 TSP + NaOH (3.45) 5.00 x 104 5.19 x 10' TSP + NaOH (3.5) 5.00 x 104 3.75 x 104 TSP + NaOH (3.7) 1.37 X 104 3.35 X 102 TSP + NaOH (4) 2.08 X 103 2.50 x 10 0 NaOH (3.1) 3.88 x 106 2.57 x 106 NaOH (3.3) 3.38 X 106 2.84 x 106 NaOH (3.5) 9.50 x 101 1.80 x 106 NaOH (3.7) 1.78 x 106 4.11 x 105 lo WO 00/18246 PCT/FR99/02226 14 B.3 Conclusion When used alone at 0.4%, anhydrous TSP induces no bactericidal action during the time of the experiment (30 s), either on a culture of 5 S. typhimurium IPL or of E. coli NIHJ-JC2. Exposing these cultures to NaOH alone (3.1 to 3.5 g/l) does not induce any bactericidal action either. However, when used at 3.7 g/l, sodium hydroxide induces a decrease in the CFU/ml by a factor of 4 to 5 on S. typhimurium and 10 E. coli, respectively. When used in combination, TSP (0.4%) and sodium hydroxide (3.2 g/l) induce a decrease of 2 log of the number of CFU/ml on the two cultures. Increasing the sodium hydroxide concentration 15 (3.7 g/l) increases the bactericidal action (-4 log) on the E. coli culture. The simultaneous addition of TSP (0.4%) and NaOH (4 g/l) induces a reduction in the number of CFU/ml by 3 log for S. typhimurium and of 6 log (limit 20 of the experiment) for E. coli. It is thus seen that strong synergism is induced between TSP (0.4%) and sodium hydroxide, when it is added at a concentration of greater than 0.4 g/l and especially greater than 3.2 g/l. STR

OEF

Claims

1. Process for treating foods, characterized in that it comprises a step of placing the said food in contact with a solution having an OH 5 concentration of between 0.02 and 0.2 N and by the fact that the said solution also comprises a tribasic salt of orthophosphoric acid such that the ratio between the initial concentration of OH~ ions, expressed as equivalents, and the concentration of orthophosphates 10 is at least equal to 1/4, advantageously to 1/3, preferably to 1.

2. Process according to Claim 1, characterized in that the content of orthophosphate species is at least equal to 0.01 M and not more than 15 0.1 M.

3. Process according to either of Claims 1 and 2, characterized in that the initial content of OH ions is at least equal to 0.05 N.

4. Process according to one of Claims 1 to 20 3, characterized in that the initial content of OH ions is not more than 0.1 N.

5. Process according to one of Claims 1 to 4, characterized in that the content of phosphate ions is not more than 0.1 N. WO 00/18246 PCT/FR99/02226 16

6. Process according to one of Claims 1 to 5, characterized in that the content of phosphate species is at least equal to 0.02 M.

7. Process according to one of Claims 1 to 5 6, characterized in that the OH~ ions are in the form of hydroxides of alkali metals, of ammonium or of phosphonium, or of cations masked by complexation.

8. Process according to one of Claims 1 to 7, characterized in that the OH- ions are in the form of 10 sodium hydroxide or potassium hydroxide.

9. Process according to one of Claims 1 to 8, characterized in that the phosphate is an alkali metal phosphate or a mixture thereof.

10. Process according to one of Claims 1 to 15 9, characterized in that the said step is a rinsing step.

11. Process according to one of Claims 1 to 10, characterized in that the said placing in contact is carried out by dipping, spraying or misting. 20

12. Process according to one of Claims 1 to 11, characterized in that the said placing in contact is carried out at a temperature at least equal to 0 0 C and advantageously equal to 10 0 C.

13. Process according to one of Claims 1 to 25 12, characterized in that the said placing in contact WO 00/18246 PCT/FR99/02226 17 is carried out at a temperature of not more than 80 0 C and advantageously not more than 700C.

14. Process according to one of Claims 1 to 13, characterized in that the said placing in contact 5 is carried out at atmospheric pressure.

15. Process according to one of Claims 1 to 14, characterized in that the said food is an animal food.

16. Use, for bacterial decontamination, of a 10 solution with an OH~ concentration of between 0.02 and 0.2, and in that a tribasic salt of orthophosphoric acid is added thereto such that the content of ortho phosphate species is at least equal to 0.01 M and not more than 0.1 M. 15

17. Use according to Claim 16, characterized in that the ratio between the initial concentration of OH ions in the concentration of orthophosphates, expressed as equivalents, is at least equal to 1/4, advantageously equal to 1/3 and preferably equal to 1. 20

18. Use according to Claims 16 and 17, characterized in that the solution also comprises a bactericide or a bacteriostat.

19. Use according to Claims 16 to 18, characterized in that the solution also comprises not 25 more than 200 PPM of bleach (expressed as mass of chlorine C1 2 )-