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WO1994018845A1 - Procede de traitement concernant des produits liquides a base d'×ufs entiers - Google Patents

Procede de traitement concernant des produits liquides a base d'×ufs entiers Download PDF

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Publication number
WO1994018845A1
WO1994018845A1 PCT/US1994/001673 US9401673W WO9418845A1 WO 1994018845 A1 WO1994018845 A1 WO 1994018845A1 US 9401673 W US9401673 W US 9401673W WO 9418845 A1 WO9418845 A1 WO 9418845A1
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WO
WIPO (PCT)
Prior art keywords
product
whole egg
nisin
liquid whole
weeks
Prior art date
Application number
PCT/US1994/001673
Other languages
English (en)
Inventor
Mohammad H. Hamid-Samimi
James D. Schuman
Brian W. Sheldon
Original Assignee
Michael Foods, Inc.
North Carolina State University
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 Michael Foods, Inc., North Carolina State University filed Critical Michael Foods, Inc.
Priority to AU62413/94A priority Critical patent/AU6241394A/en
Publication of WO1994018845A1 publication Critical patent/WO1994018845A1/fr

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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
    • A23B5/00—Preservation of eggs or egg products
    • A23B5/08—Preserving with chemicals
    • A23B5/12—Preserving with chemicals in the form of liquids or solids
    • A23B5/14—Organic compounds; Microorganisms; Enzymes
    • A23B5/16—Microorganisms; Enzymes
    • 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
    • A23B2/7295—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
    • A23B5/00—Preservation of eggs or egg products
    • A23B5/005—Preserving by heating
    • A23B5/0055—Preserving by heating without the shell
    • 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
    • A23B5/00—Preservation of eggs or egg products
    • A23B5/08—Preserving with chemicals
    • A23B5/12—Preserving with chemicals in the form of liquids or solids
    • A23B5/14—Organic compounds; Microorganisms; Enzymes

Definitions

  • the present invention concerns the use of peptide bacteriocins in liquid whole egg products to combat coagulation and other forms of spoilage, and to combat Listeria monocytogenes .
  • Coagulation of ultrapasteurized liquid whole egg product can occur when the product is stored at abuse temperatures (i.e., temperature > 40°F) for varying periods .
  • Other types of spoilage may occur depending on the temperature and the type of bacteria in the product .
  • spoilage may take the form of changes in pH, changes in viscosity, changes in color or off odor.
  • a first object of the present invention is a method of making a packaged liquid whole egg product characterized by a preselected refrigerated shelf life of about four weeks to about 36 weeks, wherein a lanthionine bacteriocin is added to said product prior to packaging and in an amount effective to combat Bacillus-induced coagulation of said product when stored at non- refrigerated temperatures.
  • the method comprises, first, passing a liquid whole egg product as a continuous stream through a pasteurizing apparatus during which the liquid whole egg product is heated for a predetermined time and to a predetermined temperature.
  • the predetermined temperature and predetermined time are chosen to impart the preselected shelf life to the liquid whole egg product.
  • the liquid whole egg product is then aseptically packaged.
  • a lanthionine bacteriocin is added to the product prior to packaging in an amount effective to combat coagulation of the product when stored at non- refrigerated temperatures .
  • a second aspect of the present invention is a liquid whole egg product characterized by a preselected refrigerated shelf life of about four weeks to about 36 weeks .
  • the product contains a lanthionine bacteriocin in an amount effective to combat Bacillus-induced coagulation of the product at non-refrigerated temperatures.
  • Another object of the present invention is a method of combatting the growth of Streptococcus faecalis in pasteurized liquid whole egg product, wherein a lanthionine bacteriocin is added to said product prior to packaging and in an amount effective to combat the growth of S . faecalis in said product.
  • Still another object of the present invention is a method of combatting the growth of Listeria monocytogenes in ultrapasteurized liquid whole egg product characterized by a refrigerated shelf life of about four weeks to about 36 weeks, when the product is stored under non-refrigerated conditions.
  • the method utilizes lanthionine bacteriocins in amounts effective to combat the growth of Listeria monocytogenes .
  • this method also includes adjusting the pH of the liquid whole egg product to between 6 and 7.
  • a further aspect of the present invention is an ultrapasteurized liquid whole egg product with a preselected refrigerated shelf life of about four weeks to about 36 weeks, having a pH of from 6 to 7 and containing a lanthionine bacteriocin in an amount effective to inactivate, and to reduce the rate of growth of, Listeria in the product at non-refrigerated temperatures.
  • FIGURE 1A shows the effect of three concentrations of nisin on the growth of L . monocytogenes (log CFU/ml) in ultrapasteurized liquid whole egg with a pH of 7.5, stored at a temperature of 4°C. Open circles represent 0 IU/ml nisin; open triangles represent 100 IU/ml nisin; open squares represent 1000 IU/ml nisin.
  • FIGURE IB shows the effect of three concentrations of nisin on the growth of L . monocytogenes (log CFU/ml) in ultrapasteurized liquid whole egg with a pH of 7.5, stored at a temperature of 10°C. Open circles represent 0 IU/ml nisin; open triangles represent 100 IU/ml nisin; open squares represent 1000 IU/ml nisin.
  • FIGURE 2A shows the effect of three concentrations of nisin on the growth of L . monocytogenes
  • FIGURE 2B shows the effect of three concentrations of nisin on the growth of L . monocytogenes
  • FIGURE 3A shows the effect of three concentrations of nisin on the mesophilic aerobic plate count (log CFU/ml) of ultrapasteurized liquid whole egg with a pH of 7.5, stored at a temperature of 4°C. Open circles represent 0 IU/ml nisin; open triangles represent 100 IU/ml nisin; open squares represent 1000 IU/ml nisin.
  • FIGURE 3B shows the effect of three concentrations of nisin on the mesophilic aerobic plate co i.t (log CFU/ml) of ultrapasteurized liquid whole egg with a pH of 7.5, stored at a temperature of 10°C. Open circles represent 0 IU/ml nisin; open triangles represent 100 IU/ml nisin; open squares represent 1000 IU/ml nisin.
  • FIGURE 4A shows the effect of three concentrations of nisin on the mesophilic aerobic plate count (log CFU/ml) of ultrapasteurized liquid whole egg with a pH of 6.6, stored at a temperature of 4°C.
  • Open circles represent 0 IU/ml nisin; open triangles represent 100 IU/ml nisin; open squares represent 1000 IU/ml nisin.
  • FIGURE 4B shows the effect of three concentrations of nisin on the mesophilic aerobic plate count (log CFU/ml) of ultrapasteurized liquid whole egg with a pH of 6.6, stored at a temperature of 10°C.
  • Open circles represent 0 IU/ml nisin; open triangles represent 100 IU/ml nisin; open squares represent 1000 IU/ml nisin.
  • An aspect of the present invention is a method of combatting coagulation in liquid whole egg product after processing; the method uses compounds containing bacteriocins .
  • a further aspect of the present invention is a method of restricting the survival and growth of Listeria monocytogenes in liquid whole egg product stored at refrigeration temperatures; the method uses compounds containing bacteriocins.
  • the present invention may be practiced with any suitable method of ultrapasteurization that produces liquid whole egg products having extended refrigerated shelf life.
  • the method comprises, in a particular embodiment, passing the liquid whole egg product as a continuous stream through a pasteurizing apparatus, during which the liquid whole egg product is :
  • Coagulation in eggs refers to a change from the fluid to the solid or semisolid state, and is known to be caused by a number of factors including heat, mechanical means, salts, acids, alkalis, and other reagents such as urea. See Cunningham, Egg-Product Pasteurization, in Stadelman and Cotterill (Eds.) Ecrg Science and Technology, 249 (1990) .
  • U.S. Pat. No. 5,096,728 to Rapp discloses the addition of organosulfur compounds to egg products prior to pasteurization to reduce coagulation due to heating during the pasteurization process, however, Rapp does not address coagulation after ultrapasteurization due to storage at abuse temperatures.
  • “combatting coagulation” refers to reducing the extent of coagulation that would otherwise be experienced.
  • the method comprises, in a particular embodiment, passing the liquid whole egg product as a continuous stream through a pasteurizing apparatus, during which the liquid whole egg product is: (a) heated to a predetermined holding temperature, then
  • a lanthionine bacteriocin is added to the product prior to packaging in an amount effective and at a pH effective to combat the survival and growth of Lis teria monocytogenes in the product when stored at non- refrigerated temperatures.
  • the predetermined time and predetermined temperature are chosen to impart a preselected shelf life to the liquid whole egg product.
  • a lanthionine bacteriocin may be added in amounts effective to essentially prevent an increase in the numbers of Listeria monocytogenes organisms in the liquid whole egg product for two weeks when stored at 10°C.
  • Ultrapasteurization refers to processes that decrease the number of spoilage microorganisms to levels lower than obtained with a pasteurization process to thereby obtain a product with an extended shelf life under refrigerated conditions.
  • Representative processing techniques are exemplified in U.S. Pat. Nos. 4,808,425 and 5,019,408 to Swartzel, Ball and Hamid-Samimi, which disclose ultrapasteurization of liquid whole egg products using continuous flow, high temperature, short time pasteurization equipment (the disclosures of all U.S. Patent references cited herein are to be incorporated herein by reference) .
  • 5,019,407 to Swartzel and Ball discloses a pasteurization process using an egg yolk product stream and an egg white product stream, wherein the egg yolk product stream is heated to a predetermined temperature greater than the highest temperature of the egg white product stream, and product streams are recombined to equilibrate to a second predetermined temperature.
  • the use of the present invention is not dependent on the method of ultrapasteurization used. Both batch ultrapasteurization and continuous stream methods of ultrapasteurization may be used. It will also be readily appreciated that use of the present invention is not dependent on the method of heating utilized in the ultrapasteurization process. Methods of heating utilized in ultrapasteurization procedures may include, but are not limited to, direct contact with a heated surface ⁇ see, e . g. , U.S. Pat. Nos. 4,808,425; 4,957,760; and 5,019,408), steam injection ⁇ see, e . g. U.S. Pat. No. 4,675,202) , steam infusion ( see, e . g. , U.S. Pat.
  • prior to packaging means any time prior to aseptic packaging of the egg product, and includes prior to ultrapasteurization of an egg product, during ultrapasteurization of an egg product, and following ultrapasteurization of an egg product but prior to packaging.
  • whole egg products which can be pasteurized in liquid form by the techniques described above include whole egg, fortified whole egg (whole egg with added yolk) , salt whole egg (e.g., salt 10%) , sugar whole egg (e.g., sugar 10%) , blends of whole egg with syrup solids, syrups, dextrose and dextrins and/or gums and thickening agents, blends of whole eggs with less than 1% sugar and/or salt, scrambled egg mixes (for example, a mix of about 51% egg solids, 30% skim milk solids, 15% vegetable oil and 1.5% salt) , reduced cholesterol egg products and blends thereof, custard blends, and the like.
  • whole egg fortified whole egg (whole egg with added yolk)
  • salt whole egg e.g., salt 10%
  • sugar whole egg e.g., sugar 10%
  • blends of whole egg with syrup solids, syrups, dextrose and dextrins and/or gums and thickening agents blends of whole eggs
  • Products which are extremely sensitive to thermal processing and which are particularly suitable for ultrapasteurization by the present invention include, for example, liquid whole egg and blends thereof (less than 2% added non-egg ingredients) , fortified whole egg and blends thereof (24- 38% egg solids, 2-12% added non-egg ingredients) , liquid salt whole egg, liquid sugar whole egg, and other liquid whole egg blends which are 24-38% egg solids and 12% or less of added non-egg ingredients.
  • Terms used herein have their standard meaning in accordance with industry and regulator usage. See, e.g., 7 C.F.R. ⁇ 59.570 (b) (1985) .
  • Ultrapasteurized liquid whole egg products are sold to both retail and institutional markets.
  • the product has a shelf-life of 4-36 weeks, or more preferably 8-36 weeks, if refrigerated.
  • refrigerated means maintained at a temperature below 40°F but above freezing. If stored at abuse temperatures the shelf-life of the product is reduced. Abuse temperatures are defined as those temperatures above 40°F.
  • the product may temporarily be subjected to abuse temperatures during shipping.
  • Coagulation is noted to be primarily a temperature abuse problem, in that all product will coagulate when held at elevated temperatures. The abuse time necessary to cause coagulation varies depending on the initial numbers of microorganisms present, the types of organisms present, and the temperature of abuse. Coagulation results in a lowered pH and changed color of the product . Other types of spoilage may or may not occur concurrently with coagulation; other types of spoilage may occur without coagulation. In addition to coagulation, spoilage is considered to include any signs of off color, off odor, or change of pH or viscosity in the product.
  • United States Department of Agriculture- prescribed conventional pasteurization processes for LWE are designed to provide a 9 orders-of-magnitude (9-D) process for inactivation of salmonellae in the average particle (USDA, Egg Pasteurization Manual, ARS 74-48, Poultry Laboratory, Agricultural Research Service, United States Department of Agriculture, Albany, CA (1969)) .
  • Listeria thermal inactivation studies conducted by Foegeding and Leasor (1990) indicate that such conventional minimal pasteurization processes would effect only a 2.1 to 2.7-D inactivation of L . monocytogenes in LWE; thus, the margin of safety provided by conventional pasteurization processes is substantially lower for L. monocytogenes than for most Salmonella species .
  • Nisin is a bacteriocin with known activity against Bacillus species and against certain strains of Streptococcus, and is widely used as a food additive. Bacteriocins are proteins produced by certain bacteria, and have a lethal effect on other bacteria. Bacteriocins generally have a narrower range of activity than antibiotics and are more potent. Nisin is produced by several strains of the bacterium Streptococcus lactis (also known as Lactococcus lactis) , and can be isolated and concentrated from cultures of Streptococcus lactis or from recombinant microorganisms containing DNA encoding for nisin production. See Cheeseman and Berridge Biochem . J.
  • NISAPLIN TM
  • TM NISAPLIN
  • TM has a standardized activity of 1 x 10 6 IU of nisin/g and contains 25 mg nisin/g. The activity of pure nisin is 40 times that of NISAPLIN (TM) .
  • Nisin has activity against a range of Gram positive bacteria, particularly the spore formers. Nisin is known to inhibit the majority of spore forming species of Clostridium and Bacillus with the spores being more sensitive than the vegetative cells. Nisin action against spores is sporicidal . It has been demonstrated that heat-damaged spores are more sensitive to nisin than non heat-damaged spores. See Delves-Broughton, Food Technology, 106-113, (Nov. 1990) . A summary of nisin' s properties can be found in Hurst, A. Advances in Applied Microbiology 27:85-123 (1981) .
  • Nisin is used as a preservative in dairy products such as processed cheese, cream, and milk.
  • Nisin has also been used to control post-processing contamination in processed meat (US Pat. No. 5,015,487) and in a process for deacidifying wine (US Pat. No. 5,059,431) . Its use has been disclosed for preventing Clostridium botulinum contamination in canned vegetables, cold meat products and wet fish systems. (U.S. Patent No. 4,597,972) .
  • a summary of the international use of nisin as a food additive may be found in Delves-Broughton, Food Technology, 106-113 (Nov. 1990) .
  • Nisin is one of a group of lanthionine- containing polypeptides.
  • Lanthionine-containing polypeptides are also known as lantibiotics, and are produced by Gram-positive bacteria of different genera. For a recent review of lantibiotics, see Lantibiotics: A Survey G. Jung (Ed.) 1991.
  • Lantibiotics which may be useful in the present invention include, but are not limited to, nisin, subtilin (Gross et al . Z. Physiol . Chem . , 354, 810
  • a nisin preparation in the commercial form of NISAPLIN (TM) from Aplin and Barrett proved to be effective in combatting coagulation and in retarding other forms of spoilage in ultrapasteurized liquid whole egg products stored at abuse temperatures (> 40°F) .
  • the present method uses nisin in a range of from 10 - 10,000 IU/g of liquid whole egg product, and more preferably in the range of from 100-500 IU/g of liquid whole egg product, to combat Bacillus-induced coagulation and other forms of spoilage of ultrapasteurized liquid whole egg product stored at temperatures over 40°F.
  • the method can also be used in pasteurized liquid whole egg products.
  • ATCC 7644 (log 3.6 CFU/ml) by nisin (3,700 IU/ml) in trypticase soy broth occurred more rapidly at pH 5.5 and 5.9 than pH 6.5 or 7.0.
  • Harris et al . J " . Food Prot . , 54, 836-840, (1991) , demonstrated that the lethality of nisin (37 to 1850 IU/ml) in BHI agar was increased when the pH of the medium was reduced from 6.5 to 5.5 with HCl or lactic acid.
  • Mohamed et al . Food antibiotic nisin: Comparative effects on Erysipelothrix and Listeria, In Woodbine, M.
  • the dissociation constant (pK a ) of most organic acids lies between pH 3 and 5. Since the undissociated form of the acid is believed to be responsible for the antimicrobial effect, organic acids themselves generally show antibacterial activity only in foods with pH values below 5.0 (Doores, Organic Acids. pp. 95-136. In Davidson, P.M. and Branen, A.L. (eds.) Antimicrobials in Foods, 2nd ed. , Marcel Dekker, Inc., New York (19 ⁇ 3) .
  • NISAPLIN (TM) (Aplin and Barrett) proved to be effective in combatting Listeria monocytogenes in ultrapasteurized liquid whole egg products.
  • the present method uses nisin in a range of from 10 - 10,000 IU/g of liquid whole egg product, and more preferably in the range of from 100-1,000 IU/g of liquid whole egg product, to combat survival and growth of L. monocytogenes in ultrapasteurized liquid whole egg product stored at temperatures over 40°F.
  • the method can also be used in pasteurized liquid whole egg products.
  • the pH of the liquid whole egg product is decreased to below 7.5; preferably the pH is between 6 and 7.
  • This decrease in pH acts synergistically with lanthionin bacteriocins to increase the anti-listerial effects of the bacteriocins.
  • the alteration in pH may be accomplished using any suitable means, including inorganic acids (for example, phosphoric acid) or organic acids.
  • Organic acids are preferred including, but not limited to, citric acid, acetic acid, lactic acid and malic acid. Citric acid is presently most preferred.
  • the term “combat” or “combatting” in reference to microorganisms in egg products may refer to either a decrease in absolute numbers of a microorganism over time, or a decrease in the rate of growth of a microorganism (over that rate which would otherwise be experienced) .
  • °C means degrees Centigrade
  • °F means degrees Fahrenheit
  • ml means milliliter
  • g means gram
  • mm means millimeter
  • M means molar
  • ⁇ l means microliter
  • w/v means weight per volume
  • v/v means volume per volume
  • h means hour
  • LWE means liquid whole egg
  • BHI means brain heart infusion
  • PW means peptone water
  • MIC minimum inhibitory concentration
  • IU means international units
  • SPC standard plate count
  • CFU means colony forming units.
  • Samples of unspoiled and spoiled ultrapasteurized liquid whole egg product and reduced cholesterol ultrapasteurized liquid whole egg product, as well as raw (non-ultrapasteurized) reduced cholesterol liquid whole egg product and raw whole eggs were plated on Brain Heart Infusion Agar, Trypticase Peptone-Glucose- Yeast Extract Agar (TPGY) , YM agar (for yeast/molds) , Plate Count Agar (PCA) , Mannitol-Egg Yolk-Polymyxin agar (MYP) and MRS agar + CaCo 3 (for lactobacilli) .
  • TPGY Trypticase Peptone-Glucose- Yeast Extract Agar
  • YM agar for yeast/molds
  • PCA Plate Count Agar
  • MYP Mannitol-Egg Yolk-Polymyxin agar
  • MRS agar + CaCo 3 (for lactobacilli)
  • Samples were plated both without heat shocking and after heat shocking for 10 minutes at 80°C or 20 minutes at 60°C. Heat shocking helps select for spore- forming microorganisms .
  • MRS plates were incubated microaerophilically at room temperature, TPGY plates were incubated anaerobically at 30°C, and the rest were incubated aerobically at 30°C. The resulting microbiological growth was examined and characterized. Samples of spoiled reduced cholesterol ultrapasteurized liquid whole egg product (pH 5.65 with a firm, yogurt-like consistency and a slightly lighter color, resulting from temperature abuse) grew 3 x 10 7 - 3 x 10 8 /ml of two very similar colony types.
  • Samples of unspoiled reduced cholesterol ultrapasteurized liquid whole egg product (pH 7.0-7.05) grew 7 x 10 3 /ml gram-positive, catalase-negative short rods/cocci, possibly lactobacilli.
  • Samples of spoiled ultrapasteurized liquid whole egg product (pH 5.6 with a similar consistency as spoiled reduced cholesterol ultrapasteurized liquid whole egg product) grew 2 x 10 6 /ml Group I Bacillus, and 2 x 10 5 /ml gram-positive, catalase-negative short rods/cocci.
  • Samples of unspoiled ultrapasteurized liquid whole egg product (pH 7.1) had no detectable colonies; if any bacteria were present their numbers were below 10 1 /ml.
  • Samples of raw (unpasteurized) reduced cholesterol liquid whole egg product contained 10 s /ml similar short rods/cocci, as well as 10 4 /ml very motile short gram-negative rods. No Bacillus were detected, although they may have been present at less than lOVml.
  • Raw whole eggs (pH 7.1) had a total aerobic plate count of 2 x 10 3 /ml, which included at least 10 colony types, and a wide variety of rods and cocci. No Bacillus were detected, although they may have been present at less than 10 1 /ml.
  • BCD beta-cyclodextrin
  • Bacillus isolates were identified as Bacillus cereus, and one was identified as a closely related species, Bacillus thuringi ens is .
  • Tubes of phosphate buffer and tubes of unspoiled reduced cholesterol ultrapasteurized liquid whole egg product were prewarmed in a 70°C water bath. Isolates (both Bacillus and short rods/cocci) were added at an initial concentration of ⁇ 10 4 /ml . After four minutes, the tubes were removed, cooled quickly in an ice water bath, diluted, and plated.
  • ultrapasteurized liquid whole egg product and reduced cholesterol ultrapasteurized liquid whole egg product contain at least one strain of Bacillus cereus and also gram- positive short rods/cocci (possibly a lactobacillus) , both which are able to survive pasteurization at 70°C for four minutes. With temperature abuse of the product, it appears that both are able to grow to high numbers . Both are capable of lowering the pH of the product. However, Bacillus outgrows the short rods/cocci in the product and causes coagulation of the product, while the short rods/cocci do not. Coagulation of the product is not caused merely by a drop in pH.
  • Samples of reduced cholesterol liquid whole egg product were plated on three petri plates containing Standard Methods Agar (SMA) . Following bacterial growth, eight isolates were sampled from each of the three SMA petri plates, for a total of 24 isolates.
  • SMA Standard Methods Agar
  • the 24 isolates were transferred into Brain Heart Infusion (BHI) ' broth. Of the eight isolates from each single plate, six were incubated at 37°C and two were incubated at room temperature (22°C) for 18-20 hours. Following incubation, gram stains were made of the organisms in each tube. The isolates were then transferred to BHI broth and incubated at 45 and 50°C; transfers were also made into BHI broth containing 6.5% salt and to BHI broth adjusted to pH 9.6; these were incubated at 37°C. The isolates were checked for catalase activity by streaking onto Tryptic Soy Agar with Yeast Extract (TSAYE) . Catalase activity was determined by using 2 or 3 drops of hydrogen peroxide on each colony and checking for gas production.
  • TAYE Tryptic Soy Agar with Yeast Extract
  • This example illustrates that Enterococci can survive ultrapasteurization treatments and can contaminate ultrapasteurized liquid whole egg products.
  • This example demonstrates the effectiveness of nisin preparation in combatting coagulation in packages of reduced cholesterol ultrapasteurized liquid whole egg stored at abuse temperatures.
  • nisin preparation 0, 500, 1,000, 2,000, 5,000, or 10,000 IU/g of liquid egg product.
  • Packages were stored at 70°F to simulate extreme temperature abuse conditions. The results, shown in Table 1, indicate that nisin extends the time to coagulation in inoculated packages kept at abuse temperatures in a dose dependent fashion.
  • Nisin preparation was added to six non- inoculated 1/2 pint packages of reduced cholesterol ultrapasteurized liquid whole egg product at the same dosages as above (0, 500, 1,000, 2,000, 5,000, or 10,000 IU/g) .
  • Packages were stored at 70°F. Coagulation in the control package containing no nisin occurred between 36 and 48 hours. In packages containing nisin, coagulation did not occur until day 7 or 8. (Data not shown) .
  • This experiment demonstrated the effectiveness of nisin in combatting coagulation of ultrapasteurized liquid whole egg product stored at 70°F.
  • Seven 1/2 pint packages of fresh reduced cholesterol ultrapasteurized liquid whole egg product were used.
  • Nisin in the form of commercially available NISAPLIN (TM) was placed in five packages at doses of 500, 1,000, 2,000, 5,000, and 10,000 IU/g of product.
  • One package was opened but received no nisin (open control) ; one package was kept closed and received no nisin (closed control) .
  • Packages were stored at 70°F starting on 8/26/92 at 4:00 p.m. Samples were monitored daily for signs of coagulation and spoilage.
  • This example demonstrates the effect of nisin, 250 IU/g of liquid whole egg product, on microbiological growth in ultrapasteurized liquid whole egg product stored at 70°F.
  • Nisin 250 IU/g was added to ultrapasteurized reduced-cholesterol liquid whole egg product. The product was then stored at 70°F for one week. Samples were taken daily and examined microbiologically. Results are shown in Table 3 , and indicate that while the total plate count rose over time, as did the pH, the number of B. cereus organisms remained constant. At the end of one week, no coagulation was noted except at the surface of the product carton.
  • This example demonstrates the effect of nisin, 100 IU/g of liquid whole egg product, on microbiological growth in ultrapasteurized liquid whole egg product stored at various temperatures .
  • Nisin 100 IU/g product
  • Standard Plate Counts were performed on samples from the packages at various times to determine the colony forming units per gram of product
  • pH-adjusted LWE was further subdivided into triplicate sterile flasks and supplemented with 0 percent, 0.01 percent or 0.1 percent (w/v) NISAPLINTM to provide final nisin concentrations of 0, 100, and 1000 IU/ml of LWE, respectively.
  • Working stock cultures were prepared by transferring 0.1 mL of frozen stock culture to 10 mL of BHI broth incubated at 37°C for 24 hours. By transferring 0.1 mL of the working stock culture to 10 mL of fresh BHI (37°C for 24 hours) , stationary phase cultures containing 1.4 x 10 9 to 2.9 x 10 9 CFU/mL were obtained. Two milliliter aliquots of each of the 5 strains were pooled, centrifuged for 10 minutes at 9000 x g, resuspended in 10 L of 0.1 percent peptone water (PW) , and diluted 1:1000 in sterile PW to produce the final inoculum suspension.
  • PW peptone water
  • LWE used in the Listeria challenge study was inoculated at 0.2 percent (v/v) to provide a target inoculum level of 3 x 10 3 CFU/mL.
  • Lactococcus lactis subsp. cremoris ATCC 14365 a nisin sensitive indicator organism used in nisin bioassays, was obtained from Dr. F. Breidt (NC State University) and was transferred twice in MRS broth (Difco) (30°C, 24 hours) before use.
  • EXAMPLE 9 Storage Studies Individual samples for storage and evaluation consisted of 9 mL of LWE in sterile capped 16 mm diameter test tubes stored under static conditions at 4°C (39°F) or 10°C (50°F) in thermostatically controlled incubators. Unlike a previous study by Foegeding and Leasor (1990) , a mineral oil overlay (to minimize free oxygen transfer) was not added to the LWE samples due to concerns that the hydrophobic nisin molecules might partition within the oil layer.
  • the residual activity (IU/mL) of added nisin in LWE was determined by extraction and bioassay using a horizontal agar well diffusion assay developed by Aplin & Barret, Ltd. (Anonymous, Laboratory method: Nisin assay (egg) , Laboratory procedure 25.1.93, pp. 1-10, Aplin S Barrett Ltd., Dorset, England, 1993) .
  • the procedures used in the present study differed only in the indicator microorganism (Lactococcus lactis subsp. cremoris ATCC 14365) and the agar medium (MRS agar, Difco) used for well diffusion testing. The use of this L. lactis subsp.
  • cremoris strain in nisin bioassays has been previously described (Harris et al . , Appl . Environ . Microbiol . 58, 1477-1483 (1992)) .
  • Purified nisin with a potency of 3.7 x 10 7 IU/g was obtained from Aplin & Barrett, Ltd. (Dorset, England) .
  • nisin concentrations of 0 to 1000 IU/mL (in 10 increments) were obtained by the addition of small volumes ( ⁇ 12 ⁇ l) of sterile purified nisin stock solution (8 x 10 4 IU/mL) to each lOmL tube of BHI broth. The addition of the nisin stock solution did not alter the equilibrium pH of the media. A series of triplicate tubes of BHI broth encompassing 10 nisin levels was prepared for each of the three pH variables .
  • L. monocytogenes test strains were diluted in PW to provide a final inoculum level (1% v/v) of approximately 2 x 10 3 CFU/mL of pH adjusted, nisin-supplemented BHI broth. Tubes without nisin served as positive controls and uninoculated tubes containing nisin were used to verify the sterility of the test media. Growth of L. monocytogenes was monitored by visual observation for turbidity after incubation at 37°C for 7 days (no changes in growth patterns were observed after additional incubation for a total of 10 days) . The presence of L.
  • L. monocytogenes either nisin-resistant cells or cells which evaded the effect of nisin
  • pH 7.5 LWE containing nisin at 1000 IU/mL The inhibitory effect of nisin at 1000 IU/mL against L. monocytogenes during modest periods of simulated temperature abuse
  • Table 6 summarizes the effects of the presence of various L. monocytogenes populations on the pH and shelf life (i.e., elapsed time to detectable spoilage) of inoculated ultrapasteurized LWE.
  • Relatively large populations of L. monocytogenes ( ⁇ 6.4 log CFU/mL) achieved at 4°C in pH 7.5 LWE resulted in only minor changes in product pH and no detectable changes in product sensory quality.
  • overt spoilage of LWE occurred within 8 to 12 weeks due to the growth of competing psychrotrophic spoilage microorganisms identified as Xanthomonas spp (non-pathogenic) .
  • the growth of the spoilage strain lagged behind that of L.
  • nisin in ultrapasteurized LWE was monitored using a bioassay procedure at intervals throughout the Listeria challenge study. The nisin concentrations reported are based on the construction of independent standard curves. The activity of nisin in LWE was generally more stable during storage at 4°C than at 10°C at both pH values tested
  • Nisin detection limits vary by sampling date due to differences between linear regression e ⁇ uations generated for each purified msin standard curve
  • nisin was shown to be more bactericidal to L. monocytogenes in LWE at pH 6.6 than at pH 7.5, the effects of pH (7.6 vs. 6.7) and acidulant (citric acid vs . hydrochloric acid) on the minimum inhibitory concentration (MIC) of purified nisin against L. monocytogenes was investigated.
  • a secondary objective was to determine whether nisin levels below 1000 IU/mL would inactivate L. monocytogenes populations (at log 3.0 CFU/mL) in a model broth system (BHI broth) .
  • Agar media were not tested because nisin is generally more inhibitory to sensitive bacterial strains in liquid systems than in solid or semisolid systems (Ray, Nisin of Lactococcus lactis ssp lactis as a food biopreservative, pp. 207-264, In Ray B. and Daeschel, M. Food Biopreservatives of Microbial Origin, CRC Press, Boca Raton, FL (1992) ) .
  • the MIC values for five L. monocytogenes strains in BHI broth ranged from 200 to 600 IU/mL, with a mean MIC of 380 IU/mL.
  • the increased sensitivity of L. monocytogenes to nisin at reduced pH was again demonstrated in BHI broth at 37°C.
  • the mean MIC value for the five L. monocytogenes strains in BHI adjusted to pH 6.7 using the inorganic acid HCl was 220 IU/mL (a mean MIC reduction of 42% relative to the pH 7.6 controls) .
  • Strain 675-3 was an exception to this trend, with an MIC of 200 IU/mL at both pH 7.6 and 6.7 (HCl) .
  • NISAPLINTM on the organoleptic shelf-life and equilibrium pH of the product (Table 9) and on residual nisin concentrations (Table 10) during storage at 4°C and 10°C.
  • the effects of the above variables on naturally-occurring microbial populations were evaluated by determining mesophilic aerobic plate counts (surface plating onto PCA, 37°C, 48h) and mesophilic aerobic spore counts (heat-shocked diluted samples surface plated onto TGE agar, 37°C, 48h) .
  • Spoilage was defined as the first sampling period at which changes in the color, consistency, or aroma of the liquid egg were detected. pH at detectable spoilage or at the end of the 12-week storage study.

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  • Food Science & Technology (AREA)
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  • Microbiology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Meat, Egg Or Seafood Products (AREA)

Abstract

L'invention concerne un procédé permettant de combattre la coagulation induite par Bacillus dans un produit liquide à base d'÷ufs entiers caractérisé par une durée de conservation sous réfrigération allant d'environ 4 à environ 36 semaines. Ce procédé consiste à ajouter une lanthionine bactériocine à ce produit en une dose efficace pour combattre sa coagulation. L'invention concerne aussi des produits liquides ultra-pasteurisés à base d'÷ufs entiers obtenus par ce procédé, ainsi qu'un procédé permettant de combattre la croissance de S. faecalis dans un produit liquide pasteurisé à base d'÷ufs entiers. L'invention concerne enfin un procédé permettant de combattre la croissance de l'espèce Listeria dans un produit liquide pasteurisé à base d'÷ufs entiers, et qui consiste à ajouter une lanthionine bactériocine à ce produit.
PCT/US1994/001673 1993-02-17 1994-02-17 Procede de traitement concernant des produits liquides a base d'×ufs entiers WO1994018845A1 (fr)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996038045A1 (fr) * 1995-06-02 1996-12-05 Knipper Aloysius J Procede de production d'÷uf liquide a longue duree de conservation aux temperatures ambiantes
US5670198A (en) * 1992-04-02 1997-09-23 Reznik; David Method for rapidly cooling liquid egg
WO2006012085A1 (fr) * 2004-06-24 2006-02-02 Cargill, Incorporated Procédé consistant à allonger la durée de conservation de produits à base d'oeufs via un traitement à haute pression
EP2178401A4 (fr) * 2007-07-20 2011-02-02 Cargill Inc Traitement d'un effluent
CN104770464A (zh) * 2015-04-24 2015-07-15 北京农学院 一种蛋液的低温保存方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989012399A1 (fr) * 1988-06-22 1989-12-28 Public Health Research Institute Of The City Of Ne Compositions de nisin utilises comme herbicide ameliore de champ d'action tres etendu
EP0384319A1 (fr) * 1989-02-21 1990-08-29 Viskase Corporation Compositions antimicrobiennes, film et méthode pour le traitement de la surface de denrées alimentaires
EP0427912A1 (fr) * 1989-11-16 1991-05-22 HAARMANN & REIMER CORP. Contrôle de la croissance microbienne avec des formulations de lantibiotique/lysozyme
EP0453860A1 (fr) * 1990-04-20 1991-10-30 HAARMANN & REIMER CORP. Méthode pour tuer des bactéries gram-négatives

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989012399A1 (fr) * 1988-06-22 1989-12-28 Public Health Research Institute Of The City Of Ne Compositions de nisin utilises comme herbicide ameliore de champ d'action tres etendu
EP0545911A2 (fr) * 1988-06-22 1993-06-09 Applied Microbiology, Inc. Compositions de bactériocin à lanthionine utilisées en tant que bactericides
EP0384319A1 (fr) * 1989-02-21 1990-08-29 Viskase Corporation Compositions antimicrobiennes, film et méthode pour le traitement de la surface de denrées alimentaires
EP0427912A1 (fr) * 1989-11-16 1991-05-22 HAARMANN & REIMER CORP. Contrôle de la croissance microbienne avec des formulations de lantibiotique/lysozyme
EP0453860A1 (fr) * 1990-04-20 1991-10-30 HAARMANN & REIMER CORP. Méthode pour tuer des bactéries gram-négatives

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Nisin and its uses as a food preservative", FOOD TECHNOLOGY, vol. 44, no. 11, November 1990 (1990-11-01), CHICAGO ILLINOIS, pages 100 - 112 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5670198A (en) * 1992-04-02 1997-09-23 Reznik; David Method for rapidly cooling liquid egg
WO1996038045A1 (fr) * 1995-06-02 1996-12-05 Knipper Aloysius J Procede de production d'÷uf liquide a longue duree de conservation aux temperatures ambiantes
WO2006012085A1 (fr) * 2004-06-24 2006-02-02 Cargill, Incorporated Procédé consistant à allonger la durée de conservation de produits à base d'oeufs via un traitement à haute pression
US7211287B2 (en) 2004-06-24 2007-05-01 Cargill, Incorporated Egg Products
EP2178401A4 (fr) * 2007-07-20 2011-02-02 Cargill Inc Traitement d'un effluent
CN104770464A (zh) * 2015-04-24 2015-07-15 北京农学院 一种蛋液的低温保存方法
CN104770464B (zh) * 2015-04-24 2017-12-15 北京农学院 一种蛋液的低温保存方法

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AU6241394A (en) 1994-09-14

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