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WO1997023136A1 - Procede de decontamination bacterienne - Google Patents

Procede de decontamination bacterienne Download PDF

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Publication number
WO1997023136A1
WO1997023136A1 PCT/GB1996/003173 GB9603173W WO9723136A1 WO 1997023136 A1 WO1997023136 A1 WO 1997023136A1 GB 9603173 W GB9603173 W GB 9603173W WO 9723136 A1 WO9723136 A1 WO 9723136A1
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WO
WIPO (PCT)
Prior art keywords
solution
none
sample
tsp
treatment
Prior art date
Application number
PCT/GB1996/003173
Other languages
English (en)
Inventor
Roger Joseph Miles
Claire Amanda Cassar
Alexandra Maria Da Silva Carneiro De Melo
Original Assignee
The Minister Of Agriculture Fisheries And Food
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The Minister Of Agriculture Fisheries And Food filed Critical The Minister Of Agriculture Fisheries And Food
Priority to CA 2240930 priority Critical patent/CA2240930A1/fr
Priority to AU11657/97A priority patent/AU1165797A/en
Priority to JP9523407A priority patent/JP2000503002A/ja
Priority to EP96942523A priority patent/EP0868122A1/fr
Publication of WO1997023136A1 publication Critical patent/WO1997023136A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3454—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of liquids or solids
    • A23L3/3463—Organic compounds; Microorganisms; Enzymes
    • A23L3/3571—Microorganisms; Enzymes
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
    • A23B4/00—General methods for preserving meat, sausages, fish or fish products
    • A23B4/02—Preserving by means of inorganic salts
    • A23B4/027—Preserving by means of inorganic salts by inorganic salts other than kitchen salt, or mixtures thereof with organic compounds, e.g. biochemical compounds
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
    • A23B4/00—General methods for preserving meat, sausages, fish or fish products
    • A23B4/14—Preserving with chemicals not covered by groups A23B4/02 or A23B4/12
    • A23B4/18—Preserving with chemicals not covered by groups A23B4/02 or A23B4/12 in the form of liquids or solids
    • A23B4/20—Organic compounds; Microorganisms; Enzymes
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
    • A23B4/00—General methods for preserving meat, sausages, fish or fish products
    • A23B4/14—Preserving with chemicals not covered by groups A23B4/02 or A23B4/12
    • A23B4/18—Preserving with chemicals not covered by groups A23B4/02 or A23B4/12 in the form of liquids or solids
    • A23B4/20—Organic compounds; Microorganisms; Enzymes
    • A23B4/22—Microorganisms; Enzymes; Antibiotics
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
    • A23L3/34—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
    • A23L3/3454—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of liquids or solids
    • A23L3/358—Inorganic compounds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
    • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
    • A61L2/18—Liquid substances or solutions comprising solids or dissolved gases

Definitions

  • This invention relates to a method for reducing the levels of bacteria, in particular food-borne human pathogens and spoilage organisms, which is suitable for use in food processing or elsewhere where hygiene requirements mean that bacterial levels should be controlled.
  • the method may be effective against both gram negative and gram positive bacteria. Kits for carrying out the method are also claimed.
  • PCT patent application WO 93/00822 discloses a method of destroying bacteria by use of osmotic shock treatment in combination with cold shock and/or exposure to the enzyme lysozyme. Lysozyme is well known to be effective against certain gram positive bacteria but the combined treatment extends its usefulness into the class of gram negative bacteria. However, although effective in vitro the combined treatment is not sufficiently effective against Salmonella when the method is used under practical food processing conditions.
  • US Patent 5,069,922 there is disclosed a process for treating poultry carcasses to control Salmonella growth, which comprises treating eviscerated and defeathered poultry with a solution containing an alkali metal orthophosphate, e.g. trisodium orthophosphate (TSP) , or an alkali orthophosphate combined with a minor amount of a basic reagent, e.g. sodium carbonate.
  • TSP has been accepted as safe by the US Food and Drug Association and is an ingredient of many food products, but the TSP process as disclosed in the above referenced US patent, and as used to date, has certain disadvantages. Firstly it requires a high TSP concentration (around 0.4M) and thus a high pH (approximately 12.5 at 0. M) , which may reduce its acceptability for poultry and other food treatments. Secondly, it is ineffective against gram positive spoilage bacteria and has questionable effectiveness against certain gram negative bacteria such as Campylobacter.
  • a method for reducing the levels of gram negative and gram positive bacteria in a sample comprising treating the sample with a 0.0005 to 0.2M solution of a trialkali metal orthophosphate, said treatment being combined with one or more of the following further treatments:
  • a preferred combination of further treatments comprises step (a) with either step (b) or step (c) .
  • a combination treatment as disclosed herein is effective in the destruction of gram positive bacteria, against which trialkali metal orthophosphate on its own is ineffective, and for gram negative bacteria such as Salmonella and Campylobacter.
  • the effect of the combination of the trialkali metal orthophosphate process with one or more of the other processes is synergistic in that not only is the range of bacteria destroyed greater than any of the processes separately but also it works with lower concentrations of alkali metal orthophosphate than utilised previously, indeed ones which would be otherwise non-lethal when used without the secondary stage of treatment.
  • concentrations of from 0.0005 to 0.2M, suitably from 0.001 to 0.2M and preferably from 0.005 to 0.01M of trialkali metal orthophosphate are sufficient.
  • TSP concentration of trialkali metal orthophosphate
  • the present invention has a further advantage over the previously disclosed osmotic shock plus lysozyme treatment since it does not depend upon the presence of nutrients to promote killing and treatment processes are not markedly dependent on temperature being in the range 4 to 50°C.
  • organisms washed off chicken skin surfaces were found to be highly susceptible to killing treatments and the resultant treatment solutions were relatively free of bacteria. This could be of significance in reducing cross contamination between carcasses in poultry processing.
  • the osmotic shock comprises a hypo-osmotic shock, in which water is induced to enter a cell and particularly a bacterial cell.
  • Hypo-osmotic shock is preferably preceded by administration of a hyper-osmotic shock (where water is induced to leave the cell) .
  • the osmotic shock may i>e administered using the process described in WO 93/008822, the disclosure of which is incorporated herein by reference.
  • osmotic shock may be induced in a sample by exposing the sample to a first solution having a water activity (a w ) of 0.997 or less (which induces hyper-osmotic shock) and subsequently exposing the sample to a solution of a k higher than that of said first solution (which then results in hypo-osmotic shock) .
  • a w water activity
  • the first solution has a water activity in the range 0.992 to 0.96, more preferably 0.974 to 0.96. It is suitably applied for a time in the range of 5 seconds to 30 minutes, or more preferably between 30 seconds and 20 minutes, or most preferably in the range of 1 to 10 minutes.
  • the said first solution suitably contains NaCl at a concentration sufficient to provide a water activity of 0.997 or less, for example at a concentration of about 0.8M.
  • the a w of the second solution is suitably of the order of 0.999.
  • the sample is exposed to this solution for a sufficient period of time to produce the desired hypo-osmotic shock.
  • the time may in fact be very short, of the order of a few seconds. However, long exposure times do not adversely affect the reaction.
  • an exposure time of from 5 seconds to 2 hours may be convenient, more particularly from 10 minutes to 1 hour, for example about 30 minutes.
  • the second solution may be prepared and applied separately from the first solution, or it may be created by introducing an appropriate diluent such as water, to the first solution.
  • the said first solution contains 0.001 to 0.2 M of a tri-alkali metal orthophosphate so that the treatment with this reagent is combined with the osmotic shock treatment.
  • the second solution may contain reagents used in steps (b) and (c) above, so as to combine these further treatments with the osmotic shock treatment.
  • Suitable enzymes which break down peptidoglycan for use in the method of the invention are those which are not harmful to humans, and a particular example is lysozyme.
  • Lysozyme is suitably applied to the sample in the form of an aqueous solution, for example having a concentration of at least l ⁇ gml '1 and preferably at least ⁇ gml 1 .
  • a lysozyme solution is conveniently provided in the form of a solution of freeze dried egg white which is at a concentration of at least 0.lmgml : .
  • the lysozyme may be applied in a rinse water, following treatment with trialkali metal orthophosphate, at a concentration of at least l ⁇ g ml '1 and preferably at least 5 ⁇ g ml '1 .
  • lysozyme treatment is combined with osmotic shock treatment by adding lysozyme to the second solution of higher a political.
  • bacteriocins are also those which are considered to be fit for human consumption such as nisin and pediocin, and preferably nisin is used in the method of the invention.
  • Suitable nisin treatment solutions contain nisin at a concentration of at least O.l ⁇ M, preferably l ⁇ M or more.
  • the sample is rinsed with water after treatment with the trialkali metal orthophosphate and prior to treatment with the solution containing nisin.
  • nisin is also particularly effective in killing gram positive organisms, for example, Staphylococcus aureus giving further improved kills over the other combined treatments.
  • nisin is particularly effective where there is contamination by gram positive bacteria.
  • control of TSP concentrations is desirable in order to prevent the pH of the enzyme or bacteriocin treatment, in particular lysozyme or nisin treatments respectively, being adversely affected. It may be desirable to acidify the lysozyme or nisin solution to optimise the treatment.
  • treatment solutions of bacteriocin or enzyme solutions are acidified, for example to a pH of approximately 5.0. This may be effected by inclusion of an acid to the solution, preferably an organic acid such as lactic acid. Lactic acid is suitably present at a concentration of at least 0.25mM.
  • a suitable trialkali metal orthophosphate for use in the method of the invention is trisodium phosphate.
  • the sample is suitably a portion of a foodstuff, although it may also comprise other consumable products such as pharmaceuticals, cosmetics and toiletries. However, it may also comprise surfaces of machinery, instruments or utensils, such as pipework, or working surfaces, such as food preparation surfaces or 'clean-room' surfaces where the presence of bacteria would be problematic.
  • Treatment methods used will depend upon the nature of the sample and the nature of the solution being applied. However, treatments may suitably be effected, for example by immersing the sample in a solution, or by washing and particularly spray washing the sample with a treatment solution, or a combination of these. Where treatment requires that the sample is exposed to the treatment solution for an extended period of time, for instance, where a solution with a water activity of less than 0.997 is being applied in order to induce a hyperosmotic shock, immersion may be the most convenient option, but suitably spray wash solutions may be prepared, for example by using electrostatic spraying techniques or by including film- forming chemicals such as surfactants into the solution prior to application.
  • a sample is treated with a first solution comprising a trialkali metal orthophosphate at a concentration in the range of from 0.0005 to 0.2M, suitably from 0.001 to 0.2M, said solution having a water activity (a w ) of 0.997 or less, and subsequently treating the sample with a second solution of an enzyme which breaks down peptidoglycan or a bacteriocin, said second solution having an aology higher than that of said first solution.
  • a first solution comprising a trialkali metal orthophosphate at a concentration in the range of from 0.0005 to 0.2M, suitably from 0.001 to 0.2M, said solution having a water activity (a w ) of 0.997 or less
  • the sample is sequentially immersed in said first and second solutions but alternatives such as immersion in the first solution followed by spray washing in the second solution may be used.
  • a sample of foodstuff is immersed in a solution of TSP at a concentration in the range 0.0005 to 0.2M, suitably from 0.001 to 0.2M and preferably 0.005 to 0.01M, together with a solution of sodium chloride, preferably at a concentration of about 0.8M, at a temperature in the range 4 to 50°, preferably 37°C and then spray washing with lysozyme solution, which is suitably at a concentration of >10 ⁇ g ml 1 .
  • the lysozyme solution may be provided in the form of freeze dried egg white at a concentration of about O.lmg ml 1 . This preferred process is highly effective in the killing of gram negative bacteria on vegetable material such as lettuce.
  • a sample of foodstuff is immersed in a solution of trisodium orthophosphate at a concentration in the range 0.001 to 0.2M, preferably 0.005 to 0.01M, at a temperature in the range 4 to 50°C, preferably 37°C and then spray washed with nisin at a concentration of greater than l ⁇ M.
  • the treatments of the present invention are fairly independent of temperature, it is preferred that the treatment with trialkali metal orthophosphate and the further treatment is carried out at a temperature in the range 4 to 50°C, preferably about 37°C.
  • kits for carrying out the above-described method form a further aspect of the invention.
  • These kits may comprise a trialkali metal orthophosphate and one or more of the following components:
  • the reagents may be supplied per se with instructions for forming suitable treatment solutions, or they may be supplied as ready made aqueous solutions.
  • the components of the kit will be separated in various containers, for example in multipack containers.
  • the organisms used were: Escherichia coli , Listeria monocytogenes , Pseudomonas fluorescens, Salmonella enteri tidis, Campylobacter jejuni and Staphylococcus aureus .
  • Campylobacter jejuni (NCTC 11626) , Listeria monocytogenes (NCTC 7973), Pseudomonas fluorescens (NCTC 10038) Salmonella enteri tidis (NCTC 6676) and Staphylococcus aureus (NCTC 8532) were obtained as freeze-dried cultures from the National Collection of Type Cultures, Colindale, UK. Escherichia coli (NCIMB 9485) was obtained from the Division of Life Sciences Collection, King's College.
  • cryoprotectant glycerol final concentration 15% v/v was added to early stationary phase cultures. One ml aliquots of cultures were then dispensed into sterile cryotubes and stored at -70°C.
  • C. jejuni bacteria were grown aerobically at 37°C or 30°C (Pseudojnonas only) on Brain Heart Infusion broth (Oxoid) or Nutrient agar plates (Oxoid) . Broth cultures were grown in 250ml flasks containing 25 ml medium, on a shaking incubator. C. jejuni was grown statically in 70 ml tissue culture bottles containing 25ml Brain Heart Infusion broth (Oxoid) enriched with 10% Horse serum (Oxoid) and 0.25% Yeast extract (Oxoid), or on Blood agar plates (7% v/v Horse blood (Oxoid) in Oxoid Blood agar base No 2) . Cultures were incubated at 37°C in an atmosphere of 10%(v/v) CO, and 10% (v/v) 0 2 , obtained using a gas jar and gas generating kit (Oxoid BR 60) .
  • Example 1 Killing of suspended cells.
  • the effective cell kills achieved on gram negative and gram positive organisms subjected to treatments with TSP and lysozyme and/or osmotic shock, at various temperatures and in the presence or absence of serum was tested as follows.
  • Overnight broth cultures were diluted 1/25 in fresh medium and similarly grown to the early stationary phase (approximately 4h incubation) ; growth was monitored by following culture optical density using an EEL colorimeter at 550 nm.
  • TSP TSP plus sodium chloride
  • TSP plus heat inactivated newborn calf serum up to 50% v/v,-Gibco
  • TSP plus NaCl and serum concentrations of TSP and NaCl were varied and are given in the results tables.
  • cell suspensions were further diluted (1/100) in distilled water or distilled water containing 20 ⁇ gml ' lysozyme, (Sigma L6876) .
  • Organism NaCl (M) TSP(M) pH" % cell survival -lysozyme - lysozyme
  • Organism NaCl (M) TSP(M) pH” % cell survival lysozyme -i-lysozyme
  • Tables 1 and 3 show results at 37°C on gram negative and gram positive organisms respectively and Tables 2 and 4 show results at 4°C.
  • the TSP concentrations tested ranged from 0.OM to 0.005M for the gram negative organisms and 0.OM to 0.10M for gram positive.
  • Campylobacter were not increased by lysozyme treatment, and, in combination with osmotic shock, 0.005M TSP was required to reduce the number of Campylobacter to an undetectable level. Nevertheless, even for Campylobacter, TSP killing was clearly promoted by osmotic shock.
  • TSP(>0.05M) treatment gave significantly higher kills than for either treatment alone.
  • Osmotic shock also enhanced killing by TSP (cf. killing by 0.005-0.05M TSP in presence and absence of NaCl-treatment; Tables 3 and 4), particularly at 37°C.
  • TSP gave maximal killing (no survivors detected; kills >99.7%) with very low concentrations of TSP (0.005M).
  • St.aureus was more susceptible to TSP when this treatment was combined with osmotic shock. However, in contrast to results obtained with L. monocytogenes, exposure to lysozyme did not enhance killing following either TSP and/or osmotic shock treatment. However, St. aureus was markedly sensitive to low concentrations of nisin (see Example 3) .
  • Inoculated test samples were immersed in 10 ml TSP solution, 10 ml TSP plus 0.8M NaCl, 0.8M NaCl or distilled water, as appropriate. After incubation on a rotary shaker for 10 mins at ambient temperature, or 4 or 37°C, the samples were shaken to remove excess fluid and then immersed in 10ml distilled water or distilled water containing lOO ⁇ gml '1 lysozyme (Sigma L6876) . Additionally, in some experiments, nisin (3.33 x 10 5 M) or lactic acid (2.5 x 10 '3 or 2.5 x l ⁇ "M) was added to the final treatment solution, or an additional water rinse was included prior to the final treatment.
  • the TSP concentrations used was relatively high, being based on those required to kill suspended organisms in the presence of high organic load, such as might exist at the skin surface. 5
  • TSP and TSP/osmotic shock treatments did not, in this case, appear to significantly enhance sensitivity to lysozyme, possibly due to carry over of TSP to the lysozyme 0 solution, which became alkaline.
  • Lettuce was used as a contrasting surface to that of chicken. Kills of attached E. coli clearly showed a marked synergy between TSP and subsequent lysozyme treatments, especially at lower TSP concentrations (less than 0.01M) . At higher concentrations the effect of lysozyme was less marked.
  • the results on lettuce leaves also showed a synergy between TSP and osmotic shock treatments, especially at 0.01M TSP (the highest concentration tested) . Maximal kills of E. coli on lettuce were >99% for both TSP/lysozyme and TSP/osmotic shock combined treatments. Thus, in contrast to the results observed using chicken skin, data for lettuce were much closer to those obtained for suspended cells.
  • Nisin was obtained as a freeze-dried powder (2.5% nisin with NaCl and denatured milk solids; Sigma) . It was dissolved in water and stored frozen (-70°C) as a stock solution (3mM) . After thawing, it was sterilised by membrane filtration and used at concentrations in the range 0.114 ⁇ M to 34.2 ⁇ M. The results are shown in Tables 13 to 15.
  • results shown are for cells dried on the surface of the skin, incubated in TSP at 37°C, rinsed quickly (5sec) in water and transferred to nisin solution (34.2 ⁇ M) or distilled water at 37°C.
  • Table 15 The effect of TSP and nisin plus lactic acid or nisin plus Ivsozvme treatments on the survival of S. en teri tidis attached to chicken skin.
  • results shown are for cells dried on the surface of skin, incubated in TSP at 37°C, and either (A) rinsed quickly (5 sec) in water and transferred to nisin (3 ⁇ M) or nisin plus lysozyme (lOO ⁇ g ml '1 ) at 37°C; or (B) transferred to nisin in 2.5mM lactic acid.
  • Table 13 illustrates the effect of 1.14 ⁇ M nisin on suspended cells previously treated with various concentrations of TSP.
  • the cells were: C. jejuni (4 and 37°C) E. coli (37°C) and P. fluorescens (room temperature and 37°C) .
  • nisin caused high kills (up to 7 logs) of cells previously treated with only low TSP concentrations (0.5-1.OmM, depending upon the organism) .
  • TSP concentrations 0.5-1.OmM, depending upon the organism
  • Table 14 illustrates the results of experiments where E. coli cells were dried on the outer surface of chicken skin. It can be seen that nisin markedly enhanced killing at 37°C of cells previously treated with 0.01 and 0.005M TSP; at 0.05M TSP, kills were similar in the presence and absence of nisin (data not shown) . Cell killing by nisin following exposure to low TSP concentrations was further enhanced by the introduction of a quick rinse in water, after TSP treatment and immediately prior to immersion in nisin solution. Cell kills at 0.005M TSP were consistently >99%. The high kills of E.
  • coli obtained using 0.005M TSP in combination with a further nisin treatment were comparable to those seen at very high TSP concentrations (0.4M) without nisin. Similarly high kills (99%) were also observed for C. jejuni (Table 14). S.enteritidis was more resistant, nevertheless, kills of up to 97% were observed (Table 14) . (Under the conditions used, nisin was highly effective in killing the gram positive bacterium St. aureus . Even in the absence of prior treatment with TSP, kills were >99.9% (Table 14) .
  • Table 15(B) shows the effect on killing of Salmonella when lactic acid was incorporated into the nisin washing solution.
  • the lactic acid was added to ensure an acid pH (approximately 5.0) which was near optimal for nisin activity.
  • Cell kills in the presence of nisin increased to 99%; however, of potential interest, kills in the absence of nisin were similarly high, suggesting that an increased pH shock was a significant cause of cell death.
  • Table 15(A) shows the effect of lysozyme plus nisin following TSP and combined osmotic shock/TSP treatments on E. coli attached to chicken skin as the test system.
  • both nisin and lysozyme reduced the viable count of TSP treated chicken skin by >90%.
  • kills were not further improved when skin was treated with nisin plus lysozyme.
  • a similar conclusion was reached in experiments using combined osmotic shock/TSP treatment prior to nisin and/or lysoyme treatment at both ambient and 37°C.
  • nisin and lysozyme may act antagonistically or that they affect the same population of cells.
  • results shown are for cells dried on the surface of the skin, incubated in TSP (5mM) , NaCl (0.8M) or TSP plus NaCl at 37°C, and transferred to nisin (33.3 ⁇ M) solution. Where TSP was used, a brief water rinse (5 sec) was applied immediately prior to transfer to nisin solution.
  • kills determined for TSP-nisin treatment were generally higher than those determined in experiments using unsterilised chicken (cf. Tables 14 and 16) .
  • High kills (>85%) were also observed for osmotic shock- nisin treatment (Table 16) .
  • the combined TSP plus osmotic shock and nisin treatment was most effective (cell kills >99%) . Under the conditions used, this treatment also reduced the viable count of L. moncytogenes and St. aureus (gram positive species) by approximately 5 log cycles (Table 16) .

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Abstract

L'invention concerne des procédés permettant de diminuer le taux de bactéries Gram négatives et Gram positives, et qui comportent le traitement par une solution faiblement concentrée d'un orthophosphate de métal alcalin combiné à un choc osmotique et/ou à un lysozyme en solution et/ou à de la nisine en solution. Le procédé de combinaison est synergique en ce qu'il élargit la plage de destruction effective des bactéries, il permet d'utiliser des paramètres de traitement plus adaptés que les techniques antérieures et il convient particulièrement bien pour le traitement des produits alimentaires.
PCT/GB1996/003173 1995-12-21 1996-12-20 Procede de decontamination bacterienne WO1997023136A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CA 2240930 CA2240930A1 (fr) 1995-12-21 1996-12-20 Procede de decontamination bacterienne
AU11657/97A AU1165797A (en) 1995-12-21 1996-12-20 Bacterial decontamination method
JP9523407A JP2000503002A (ja) 1995-12-21 1996-12-20 細菌汚染除去方法
EP96942523A EP0868122A1 (fr) 1995-12-21 1996-12-20 Procede de decontamination bacterienne

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9526174.9 1995-12-21
GBGB9526174.9A GB9526174D0 (en) 1995-12-21 1995-12-21 Bacterial decontamination of foods

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WO1997023136A1 true WO1997023136A1 (fr) 1997-07-03

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EP (1) EP0868122A1 (fr)
JP (1) JP2000503002A (fr)
AU (1) AU1165797A (fr)
GB (1) GB9526174D0 (fr)
WO (1) WO1997023136A1 (fr)

Cited By (4)

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WO2001005254A2 (fr) * 1999-07-14 2001-01-25 Rhodia Inc. Composition antibacterienne contre les bacteries gram positives dans les applications alimentaires
US6451365B1 (en) 2000-07-14 2002-09-17 Rhodia Inc. Antibacterial composition for control of gram positive bacteria in food applications
DE102004040960A1 (de) * 2004-08-18 2006-03-02 Gesellschaft für Chemischen und Technischen Umweltschutz mbH Verfahren zur mikrobiologischen Inaktivierung von Abfällen durch Zugabe von Salz
US7354888B2 (en) 2004-11-10 2008-04-08 Danisco A/S Antibacterial composition and methods thereof comprising a ternary builder mixture

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US5069922A (en) * 1989-02-09 1991-12-03 Eugene Brotsky Process for treating poultry carcasses to control salmonellae growth
JPH04200346A (ja) * 1990-11-19 1992-07-21 Yoshiaki Nagaura 浄化方法
WO1993000822A1 (fr) * 1991-07-10 1993-01-21 The Minister Of Agriculture, Fisheries And Food In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Destruction de bacteries gram negatif
JPH07155153A (ja) * 1993-12-07 1995-06-20 Riken Vitamin Co Ltd 食品保存剤

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EP0453860A1 (fr) * 1990-04-20 1991-10-30 HAARMANN & REIMER CORP. Méthode pour tuer des bactéries gram-négatives
JPH04200346A (ja) * 1990-11-19 1992-07-21 Yoshiaki Nagaura 浄化方法
WO1993000822A1 (fr) * 1991-07-10 1993-01-21 The Minister Of Agriculture, Fisheries And Food In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Destruction de bacteries gram negatif
JPH07155153A (ja) * 1993-12-07 1995-06-20 Riken Vitamin Co Ltd 食品保存剤

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001005254A2 (fr) * 1999-07-14 2001-01-25 Rhodia Inc. Composition antibacterienne contre les bacteries gram positives dans les applications alimentaires
WO2001005254A3 (fr) * 1999-07-14 2001-09-20 Rhodia Composition antibacterienne contre les bacteries gram positives dans les applications alimentaires
US6451365B1 (en) 2000-07-14 2002-09-17 Rhodia Inc. Antibacterial composition for control of gram positive bacteria in food applications
US6620446B2 (en) 2000-07-14 2003-09-16 Rhodia, Inc. Antibacterial composition for control of gram positive bacteria in food applications
DE102004040960A1 (de) * 2004-08-18 2006-03-02 Gesellschaft für Chemischen und Technischen Umweltschutz mbH Verfahren zur mikrobiologischen Inaktivierung von Abfällen durch Zugabe von Salz
US7354888B2 (en) 2004-11-10 2008-04-08 Danisco A/S Antibacterial composition and methods thereof comprising a ternary builder mixture

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AU1165797A (en) 1997-07-17
EP0868122A1 (fr) 1998-10-07
JP2000503002A (ja) 2000-03-14

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