Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B4/00—Preservation of 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
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B2/00—Preservation of foods or foodstuffs, in general
  • A23B2/70—Preservation of foods or foodstuffs, in general by treatment with chemicals
  • A23B2/725—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of liquids or solids
  • A23B2/729—Organic compounds; Microorganisms; Enzymes
  • A23B2/733—Compounds of undetermined constitution obtained from animals or plants
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B2/00—Preservation of foods or foodstuffs, in general
  • A23B2/70—Preservation of foods or foodstuffs, in general by treatment with chemicals
  • A23B2/725—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of liquids or solids
  • A23B2/729—Organic compounds; Microorganisms; Enzymes
  • A23B2/742—Organic compounds containing oxygen
  • A23B2/75—Organic compounds containing oxygen with doubly-bound oxygen
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B2/00—Preservation of foods or foodstuffs, in general
  • A23B2/70—Preservation of foods or foodstuffs, in general by treatment with chemicals
  • A23B2/725—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of liquids or solids
  • A23B2/729—Organic compounds; Microorganisms; Enzymes
  • A23B2/742—Organic compounds containing oxygen
  • A23B2/754—Organic compounds containing oxygen containing carboxyl groups
  • A23B2/758—Carboxylic acid esters
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B4/00—Preservation of meat, sausages, fish or fish products
  • A23B4/10—Coating with a protective layer; Compositions or apparatus therefor

Definitions

• the present invention discloses a process for inhibiting or retarding the outgrowth of bacteria on food products by treatment with a composition which includes one or more hops acid extracts or modified hops acid extracts plus one or more safe and suitable gram positive bacteristatic or bactericidal preparations from the lantibiotics, pediocin, lacticin class bacteriocin and/or lytic enzyme categories. More specifically, the process comprises using as an ingredient or applying to a food surface a composition including nisin, and/or lysozyme and beta hops acids in order to reduce or eliminate gram positive spoilage or pathogenic bacteria, and, most especially, all strains of the harmful pathogen Listeria monocytogenes.
• An important public health concern is the ability of pathogenic listerial species, especially Listeria monocytogenes, to grow at commercial refrigeration temperatures at which processed foods are normally stored for long periods of time. This ability to grow under standard conditions of distribution makes Listeria monocytogenes one of the top public health risks associated with raw and processed foods today. Any new antimicrobial system must be effective in commercial food systems, with formulation and temperature conditions reflecting actual practices. The new compositions of this patent are effective in a variety of foods, especially at the refrigerated storage and handling temperatures typical of foods at risk for listerial contamination.
• pathogenic and spoilage bacteria can occur in raw food materials, but heat processing tends to reduce bacterial loads dramatically.
• most foods are at risk for recontamination prior to packaging, distribution, and final consumption, when they may be exposed to pathogens in the food handling environment.
• selected pathogens may contaminate the already processed foods, usually at very low levels.
• pathogens primarily various listerial species, they may then grow unchecked on the food during distribution and storage until final consumption. The more such pathogens grow in a food product, the higher the risk of infection among consumers of that food product. This is a special concern for ready to eat meats and dairy products, as such foods are not heated or processed again by the user prior to consumption. In such cases, the most likely risk is from Listeria species that grow well under refrigeration. Consumption of elevated levels of any pathogen is recognized to increase the risk of infection, especially among infants, the elderly, pregnant women, and any immune compromised individuals.
• listeriosis has the highest mortality, exceeding 20% according to Meade, et al. (Food-related illness and death in the United States, CDC 5:5, Sept-Oct 1999).
• Meade, et al. Food-related illness and death in the United States, CDC 5:5, Sept-Oct 1999.
• FDA Food and Drug Administration
• USDA United States Department of Agriculture
• the subject of this invention is a novel, food grade (Generally Recognized as Safe), flavor neutral composition that targets Listeria in actual food systems, especially in processed, ready to eat meat products.
• the desired effect of such a composition is to kill or reduce the levels of Listeria bacteria in foods that are at risk for post processing survival or contamination by such species.
• risks associated with other gram positive bacteria including the above mentioned spoilage types, as well as less common strains of the Corynebacteria, Diplococci, Mycobacteria, Streptococci, and Streptomyces genuses have also been noted as problems in food products and may benefit from such a process or composition.
• U.S. Patent Nos. 5,096,718 and 5,260,061 disclosed the use of metabolites of propionic acid bacteria in certain foods to increase the shelf life of treated food products. These metabolites demonstrate enhanced efficacy against gram negative bacteria but, unfortunately, are not effective against gram positive bacteria.
• Nisin is a lantibiotic, more specifically, a polypeptide with antimicrobial properties which is produced in nature by various strains of the bacterium Lactococcus lactis. Nisin is indeed primarily effective against gram positive bacteria; however, the common gram positive pathogen Listeria monocytogenes is more resistant to nisin than most other species of gram positive bacteria. The need to enhance the activity of nisin against Listeria monocytogenes is well recognized and accounts for the fact that nisin by itself is not used as an antilisterial agent commercially.
• the 5,217,950 patent therefore suggests the combination of a chelating agent, such as disodium ethylenediaminetetraacetic acid (EDTA) or other acetate salts or citrate salts with nisin to effect a broader range of activity against both Listeria species as well as selected gram negative bacteria.
• a chelating agent such as disodium ethylenediaminetetraacetic acid (EDTA) or other acetate salts or citrate salts
• U.S. Patent Nos. 5,573,797; 5,593,800 and 5,573,801 disclose antibacterial compositions which include a combination of a Streptococcus or Pediococcus derived bacteriocin or synthetic equivalent antibacterial agent in combination with a chelating agent.
• the composition is applied to the surface of the food to be treated either by direct application or by incorporating the composition onto a flexible film casing which is placed into intimate contact with the food surface.
• the chelating agent binds free divalent cations in the outer membrane of gram negative cells, improving permeability to the antibacterial agents.
• the application of nisin alone to the surface of cooked meats is disclosed, but the efficacy of this single ingredient is so limited that it has not been employed commercially.
• U.S. Patent No. 5,458,876 suggests the combination of a lantibiotic (such as nisin) with lysozyme as an antibacterial.
• a lantibiotic such as nisin
• lysozyme breaks down the cell wall and weakens the structural integrity of the target cell so that the antibacterial agent becomes more effective in damaging or killing the bacterial cell.
• this combination proves to be effective in improving the antibacterial efficacy of nisin against Listeria monocytogenes, yielding a significant reduction, though not a complete elimination, of listeria at safe and suitable levels of use.
• EP 0 466 244 discloses a composition having improved antibacterial properties comprising a mixture of at least one of each of the following groups of compounds: (I) a cell wall lysing substance or a salt thereof , (II) an antibacterial compound and (III) an adjuvant selected from organic acids acceptable for use in food products or preparations for cosmetic use or personal hygiene or salts of these acids, phosphates and condensed phosphates or the corresponding acids, and other sequestering agents.
• (I) is lysozyme
• (II) may be a bacteriocin (e.g.
• nisin or pediocin may be acetic acid, sodium diacetate, lactic acid, citric acid, propionic acid, tartaric acid, orthophosphates, hexametaphosphates, tripolyphosphates, other polyphosphates or sequestering agents containing substituted or non-substituted amino groups, for example EDTA.
• EP 0 453 860 suggests the combination of nisin with a phosphate buffer effective at a pH of between 5.5 and 6.5 to eradicate gram negative bacteria from surfaces.
• WO 97/23136 suggests a bacterial decontamination method which involves treatment with a solution of low concentration alkali metal orthophosphate combined with either osmotic shock and/or lysozyme in solution and/or nisin in solution.
• This reference tested the combination of low concentrations of trisodium orthophosphate with lysozyme against certain bacteria on lettuce leaves or chicken skin, and the combination of low concentrations of trisodium orthophosphate with nisin against certain bacteria on chicken skin.
• Non-enzymatic preservatives mentioned in this publication are complexing agents such as citric acid and EDTA, amino acids, particularly amino acids, such as cysteine, alanine, tyrosine and glycine and nucleosides and nucleotides such as inosine 5'-inosine monophosphate or phosphates such as tetrasodiumpyrophosphate (diphosphate), sodium tripolyphosphate (triphosphate) and polyphosphate or reddening agents such as alkali metal nitrates.
• complexing agents such as citric acid and EDTA, amino acids, particularly amino acids, such as cysteine, alanine, tyrosine and glycine and nucleosides and nucleotides such as inosine 5'-inosine monophosphate or phosphates such as tetrasodiumpyrophosphate (diphosphate), sodium tripolyphosphate (triphosphate) and polyphosphate or reddening agents such as
• U.S. Patent No. 5,286,506 discloses the use of the fat soluble beta acids extract of hops for their bacteriostatic effects against Listeria monocytogenes in foods at 6 to 50 ppm by weight of the food.
• U.S. Patent Nos. 5,370,863 and 5,455,038 suggest that certain hops acid derivatives that are chemically hydrogenated may have antibacterial activity against listeria species.
• these extracts are not food grade (GRAS) and are not allowed for use in foods outside of brewing.
• composition which has a first component that includes one or more gram positive bacteristatic or bactericidal compounds from one or more of the following classes of materials: lantibiotics, pediocin, and/or lacticin class bacteriocins, or lytic enzymes, and a second component which includes one or more natural hops acids or hops resins or derivatives thereof provides excellent antibacterial properties, especially against potentially harmful bacteria of the listeria genus, by dramatically surpassing the antibacterial efficacy of any of the individual components or of previously published compositions.
• One embodiment of the present invention comprises an antibacterial composition containing as a first component: (a) one or more gram positive bacteristatic or bactericidal compounds from one or more of the following classes of materials: lantibiotic, pediocin, and lacticin class bacteriocins, and/or lysozyme, a natural enzyme from egg white; and as a second component (b) one or more hops acids or hops acid derivatives or hops resin or hops resin derivatives.
• a composition containing a lantibiotic bacteriocin, lysozyme, and beta hops acid extract is particularly preferred.
• the present invention provides a method for retarding growth, reducing viable numbers, or totally eliminating gram positive bacteria, and especially Listeria monocytogenes, in food products comprising the step of treating the surfaces of said food product with an effective amount of a composition comprising as a first component: (a) one or more gram positive bacteristatic or bactericidal compounds from one or more of the following classes of materials: lantibiotics, pediocin and lacticin class bacteriocins, or lytic enzymes; and as a second component (b) one or more hops acid or hops acid derivatives or hops resin or hops resin derivatives. It is an object of the present invention to provide a process for treating food products in order to protect against harmful bacteria and in order to maintain the antibacterial activity of the composition even on or in a fat containing food.
• An additional object of the present invention is to provide a novel composition having substantially greater antibacterial properties than previously observed for the individual components of the composition.
• the present invention provides a novel antibacterial composition and its use in a process for reducing, retarding, or totally eliminating harmful bacteria from food surfaces, even in fat containing foods.
• the novel antibacterial composition comprises: (a) one or more gram positive bacteristatic or bactericidal compounds from one or more of the following classes of materials: lantibiotics, pediocin and lacticin class bacteriocins, or lytic enzymes; and (b) one or more hops acid extracts or hops acid derivatives or hops resin or hops resin derivatives.
• the first component of the inventive composition is one or more compounds having bacteristatic or bactericidal activity against gram positive bacteria.
• Such compounds preferably include, but are not limited to lantibiotic, pediocin, and lacticin class bacteriocins and/or lysozyme from egg white, shellfish, or other natural sources.
• Combinations of more than one compound having bacteristatic or bactericidal activity against gram positive bacteria e.g., nisin and lysozyme
• a first class of gram positive bacteristatic compounds comprises a lantibiotic.
• lantibiotics was coined by Schnell et al. (1988. Nature 333:276-278) to describe a group of bacteriocins including nisin which contain the amino acid lanthionine and other "non-protein" amino acids. The common properties of these bacteriocins are reviewed by Keliner et al. (1988. Eur. J. Biochem 177:53-59) wherein they note that ". . .
• polycyclic polypeptide antibiotics possess a high content of unsaturated amino acids (dehydroalanine, dehydrobutrine) and thioether amino acids (meso-lanthionine, (2S,3S,6R)-3-methyllanthionine). Furthermore, iysinoalanine, 3-hydroxyaspartic acid and S-(2-aminovinyl)-D-cystine are found in some members.” Members of this group include nisin, subtilin, pep 5, epidermin, gallidermin, cinnamycin, Ro09-0198, duramycin and ancovenin.
• ribosomally synthesized peptide antibiotics contain from 19 to 34 amino acids and are produced by various microbes including Staphlococcus species, lactic acid bacteria, Bacillus species and Streptomyces species. In addition to their unique composition of non-protein amino acids, they can be distinguished from other polypeptide antibiotics on the basis of their specificity. Bacteriocins in general, and the lantibiotics in particular, are characterized by a very narrow spectrum of action. Thus, only a few species of bacteria are sensitive to a particular bacteriocin at practical, safe and suitable concentrations.
• Nisin is a ribosomally coded peptide which occasionally occurs as a dimer with a molecular weight of about 7000. It contains several unusual amino acids including beta-methyllanthionine, dehydroalanine, and lanthionine among its total of 34 amino acids. There are five unusual thio-ether linkages in the peptide which contribute to its stability in acid solutions. Nisin is one of the most thoroughly characterized bacteriocins, and shares remarkable homology of structure and action with other lantibiotics, for example Subtilin and epidermin [Buchman et al 1988. J. Bio. Chem. 263 (31): 16260-16266].
• Nisin is the collective name describing several closely related substances which exhibit similar amino acid compositions, and some limited range of antibiotic activity. This phenomenon is discussed by E. Lipinska in “Antibiotics and Antibiosis in Agriculture” (M. Woodbine, Ed.) 1988, pp. 103-130.
• Nisin is commercially available from Rhodia Inc. in a standardized 2.5 weight percent preparation under the trademark NovasinTM.
• Lantibiotic containing protein may also be present as a low level fermentation by-product in certain varieties of Cheddar or American cheese and in the fermented skim milk product known as MICROGARD ® MG300 .
• the lantibiotic is added to the food product in amounts between about 1 to about 100 ppm (by weight of solution used for treatment) of active ingredient (nisin), with preferred levels of 1 to 12.5 ppm, based on safety and suitability of use in foods.
• a Pediococcus bacterial metabolite specifically pediocin
• a substitute can yield efficacious results.
• the pediocins are not yet approved for use in foods, they may yet be accepted for commercial application in the future.
• the new class of streptococcal bacteriocins called lacticins, especially Lacticin 3147 as described in Irish Patent Application No. 980500, should produce similar activity against gram positive bacteria.
• both pediocins and lacticins are known to have bacteristatic activity primarily against a limited range of gram positive bacteria.
• a second class of gram positive bactericidal proteins comprises the lytic enzymes especially lysozyme, most commonly derived from egg albumin in a food grade extraction process, but also available from arctic scallops, human milk, tears, and other natural sources.
• lysozyme When lysozyme is used as an antimicrobial, it is added to the food product in amounts between about 20 to about 500 ppm (by weight of solution used for treatment), more preferably between about 50 to about 200 ppm, primarily to inhibit Clostridium tyrobutyricum in ripened cheeses. Lysozyme is not bactericidal at these levels against other gram positive bacteria, but it has been used at higher levels (greater than 1000 ppm, typically 2000 ppm or more) to remove the cell wall from a wide range of gram positive bacteria.
• Lysozymes (Muramidase; mucopeptide N-acetylmucamoylhydrolase; 1 ,4-.beta.-N acetylhexosaminodase, E.C. 3.2.1.17) are mucolytic enzymes which have been isolated from various sources and are well characterized enzymes. First discovered in 1922 by W. Fleming, egg white lysozyme was among the first proteins sequenced, the first for which a three dimensional structure was suggested using x-ray crystallography and the first for which a detailed mechanism of action was proposed. Its antimicrobial activity against gram positive bacteria is well documented, for example by V. N. Procter et al in CRC Crit.
• the molecular weight of egg white lysozyme is approximately 14,300 to 14,600, the isoelectric point is pH 10.5-10.7. It is composed of 129 amino acids which are interconnected by four disulfide bridges. Similar enzymes have been isolated and characterized from other sources including such diverse producers as Escherichia coli bacteriophage T4 and human tears. Despite slight differences (for example, the human lysozyme has 130 amino acids) the capacity for hydrolysis of acetylhexosamine polymers remains essentially the same. Accordingly, for purposes of this invention, the term lysozyme is intended to include those cell wall or peptidoglycan degrading enzymes which have the ability to hydrolyze acetylhexosamine and related polymers.
• Lysozyme is known to kill or inhibit the growth of bacteria and fungi, and is used in Europe to control the growth of the spoilage organism Clostridium tyrobutyricum in a wide variety of cheeses. It has also been proposed for use in a variety of other food preservation applications and has been reported to inhibit the growth of (and in some cases kill) Listeria monocytogenes (Hughey et al, 1987, Appl. Environ. Microbiol 53:2165-2170). Lysozyme derived from egg albumin with an activity of about 20,000 Shugar units/mg is commercially available from Rhodia under the trademark NovaGARDTM.
• the first component of the novel composition is preferably the previously disclosed combination of lantibiotics and lytic enzymes, especially the more preferred combination of nisin and egg white lysozyme.
• the second component of the novel composition is one or more hops acid extracts or hops acid derivatives or hops resins or hops resin derivatives or combinations of some or all of these.
• the bitter components of the hops used in beer making, particularly the beta-acids have now been found to be useful as bactericidal agents in food products, particularly in combination with the above mentioned bacteristatic and/or bactericidal components.
• the most prevalent groups of bitter acids contained in hops are the alpha-acids and the beta-acids, also referred to as humulones and lupulones, respectively. Both contribute bitterness to beer, but the alpha-acids are much more bitter than the beta-acids and not desirable for use in most food products.
• a by- product of the operation is a product which contains approximately 61 weight percent beta-acids, the remainder consisting essentially of hops resins. This by-product can be standardized with malto dextrin or other food grade carrier, spray dried, and used as an antibacterial food ingredient.
• a preferred beta hops acids composition is commercially available as a natural flavor extract containing 1 weight percent beta hops acids.
• the alpha-acids contained in hops are commonly known as humulone, cohumulone and adhumulone, while the beta-acids contained in hops are commonly known as lupulone, colupulone and adlupulone.
• Chemically modified derivatives of hops acids or hops resins which have demonstrated antibacterial properties such as hexahydrocolupulone and tetrahydroisohumulone, as disclosed in U.S. Patent No. 5,455,038, are specifically contemplated for use in association with the present invention.
• Also considered as specifically contemplated for use in association with the present invention is the use of the acid salt forms of the hops acids or hops resins.
• the hops acid or resin or derivatives thereof is added to the food product in amounts between about 0.1 to about 50 ppm of active ingredient (by weight of solution used for treatment), more preferably between about 0.40 to about 20 ppm.
• guar gum is present in the inventive composition to aid in the binding of the antimicrobial components to the food surface being treated.
• the addition of these materials is not considered critical to the success of the present invention and would be considered within the skill of the artisan.
• the antimicrobial composition of the present invention may be used in connection with any food product which is susceptible to microbial degradation. These include, but are not limited to fruits and vegetables including derived products, grain and grain derived products, dairy foods, meat, poultry, and seafood. In particularly preferred embodiments, the composition is used in connection with meat, poultry and/or seafood, more particularly with fat containing cooked meats such as hotdogs, sausages, roast beef, turkey, corned beef and deli meats.
• the novel composition is simply applied to the food surface either before or after cooking.
• the application of the composition of matter to the food surface may either be a direct application or an indirect application.
• the use of the term "food surface” is defined to include any and all internal or external surfaces of the food product being treated.
• composition according to the present invention is most readily used by applying it on the exterior surface of a blended food product, such as a hot dog or bologna, or of a solid food, such as a piece of roasted beef, so as to minimize loss of activity in the fat phase of the food.
• a blended food product such as a hot dog or bologna
• a solid food such as a piece of roasted beef
• the composition may alternatively be included in the emulsion or raw ingredients of a food such as sauces or salsas, before or after cooking, or to the interior of solid products, such as hams, by injection or tumbling.
• the composition may be applied as a marinade, breading, seasoning rub, glaze, colorant mixture, and the like, the key criteria being that the antimicrobial composition be available to the surface subject to bacterial degradation.
• the composition may be indirectly placed into contact with the food surface by applying the composition to food packaging materials or casings and thereafter applying the packaging to the food surface.
• the use of surface treatment strategies, whether direct or indirect, benefits from the minimization of loss into the fat phase of the fat containing food product.
• the bacteristatically or bactericidally optimum effective amount to be used will depend on the composition of the particular food product to be treated and the method used for applying the composition to the food surface, but can be determined by simple experimentation.
• the antibacterial composition comprises from about 38.5 to 99.8 parts by weight of the first component, which includes at least one bacteristatic or bactericidal compound selected from the group consisting of lantibiotics, pediocin, lacticin class bacteriocins, and lytic enzymes; to about 61.5 to 0.2 parts by weight of the second component, which includes at least one compound selected from the group consisting of hops acids, hops acid derivatives, hops resins, and hops resin derivatives; all parts by weight being based on the total weight of the first and second components of the composition.
• the first component which includes at least one bacteristatic or bactericidal compound selected from the group consisting of lantibiotics, pediocin, lacticin class bacteriocins, and lytic enzymes
• the second component which includes at least one compound selected from the group consisting of hops acids, hops acid derivatives, hops resins, and hops resin derivatives
• the composition comprises, as a first component, from about 1.0 to 2.5 parts by weight lantibiotic, and from about 37.5 to 97.3 parts by weight lytic enzyme; and as a second component, from about 61.5 to 0,2 parts by weight of at least one compound selected from the group consisting of hops acids, hops acid derivatives, hops resins, and hops resin derivatives; all parts by weight being based on the total weight of the first and second components of the composition.
• Example 1 illustrates the broad range antimicrobial compositions which constitute the present invention.
• Lysozyme 50 ppm 6.3 x 10e6 2.5 x 10e7
• Beta hops acid BHA* 5 ppm 1.2 x 10e8 6.2 x 10e6
• BHA beta hops acids
• hot dogs are inoculated with Listeria monocytogenes.
• the hot dogs are dipped into suspensions containing either (1) NovasinTM, lysozyme and BHA; or (2) NovasinTM and BHA, and then inoculated with L. monocytogenes on the surfaces.
• the hot dogs are then packed in sterile bags and kept at 10°C for 13 days. On each sampling day, the hot dogs are rinsed with sterile saline and the resins are plated on Listeria select agar to obtain a Listeria count.
• Enrichment is performed for the hot dogs by transferring 1 ml of the rinse to BHI broth and incubating for 24 hr, followed by plating on Listeria selective agar. The treatments that have a 0 count on Listeria select agar after enrichment are considered as negative and reported as a fraction of total treated samples.
• Table 2 shows that while NovasinTM and BHA dipping significantly reduces the initial levels of Listeria monocytogenes on hot dogs, the three component combination reduces the levels of Listeria monocytogenes to practically undetectable levels, either by direct plating, or by enrichment recovery techniques. In this three component combination there is no observed survival of viable Listeria monocytogenes, as confirmed by the negative results (3/3) after sensitive enrichment techniques that are used to recover low levels of damaged cells. The finding that all of the samples treated with the novel three component combination were negative for Listeria monocytogenes even after enrichment is the most unexpected finding of this application. No such finding has previously been reported using any one of these antimicrobial ingredients at the safe and suitable usage levels described herein.
• Efficacy of the inventive composition for cooked hams is demonstrated in Table 4.
• Cooked hams were inoculated with Listeria monocytogenes on the surface, and then topically treated by spraying the surface with a solution of either NovasinTM, lysozyme and BHA (Treatment A); or lysozyme and BHA (Treatment B); .
• the hams were then shrink wrapped and vacuum packed in sterile bags and stored at 40F (4° C) for 60 days. On each sampling day, the hams were rinsed with sterile buffer and the resins were plated on Listeria select agar to determine the viable Listeria count.
• Enrichment methods were performed for samples with Listeria count below detectable plate count levels by transferring 1 ml of the rinse to brain heart infusion (BHI) broth and incubating for 24 hr, followed by plating on Listeria selective agar. Treatments that had a negative (less than 1/ml) count on Listeria select agar after enrichment are considered as negative and reported as a fraction of total treated samples.
• BHI brain heart infusion
• Table 4 shows that the three component combination reduced the inoculated Listeria monocytogenes to undetectable levels, either by direct plating, or by enrichment recovery techniques while the control group increased 10,000 fold (4 logs).
• the two way "lysozyme plus BHA" combination showed inhibition but was not as bactericidal.
• the data demonstrate that topical application of the preferred three component composition can completely eliminate Listeria monocytogenes in a high fat processed food such as cooked ham.
• Efficacy of the inventive composition for protecting wieners from Listeria. monocytogenes is demonstrated in Table 5.
• the composition of Novasin and BHA was delivered onto the surface of wieners by incorporation of the composition into the cellulosic casing that contains the hotdog emulsion during cooking. After cooking, the casings were peeled off, and then the finished wieners were surface inoculated with Listeria monocytogenes and vacuum packed in sterile bags.
• the packaged, inoculated wieners were stored at 40°F (4 C) for over 60 days, with fresh packages opened for each sampling point. At each sampling, the wieners were rinsed along with their package using sterile buffer and the buffer solutions were then plated on Listeria select agar to determine the viable Listeria count.
• Table 5 shows that the two component combination inhibited growth of Listeria monocytogenes for more than 61 days, and resulted at the end of incubation in a greater than 4 log (10,000 fold) Listeria reduction compared to the controls.
• the data demonstrate that casing delivered application of the preferred two component composition prevents the outgrowth of Listeria monocytogenes on wieners and may be a commercially practical way to deliver the composition and thereby improve the safety of wieners and sausages. More importantly, the surface application method permits the activity of the components to be fully realized, even in the high fat environment of a typical hot dog emulsion.

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