Effects of pH and Agitation on the Growth of Listeria monocytogenes Scott A in Brain Heart Infusion Broth Containing Combined Potassium Lactate and Sodium Diacetate during Storage at 4 or 10°C

2003 ◽  
Vol 66 (8) ◽  
pp. 1469-1473 ◽  
Author(s):  
K. S. YOON ◽  
C. N. BURNETTE ◽  
R. C. WHITING
Keyword(s):  
Listeria Monocytogenes ◽  
Brain Heart Infusion ◽  
Lag Time ◽  
Low Ph ◽  
Brain Heart Infusion Broth ◽  
Limited Effect ◽  
Potassium Lactate ◽  
Effects Of Ph ◽  
Sodium Diacetate ◽  
Kinetics Of

The objective of this study was to compare the effects of pH on the growth kinetics of Listeria monocytogenes Scott A in static and agitated broths stored at 4 and 10°C with and without a combination of 1.85% potassium lactate (PL) and 0.13% sodium diacetate (SDA) (3.3% of a 60% commercial solution, PURASAL P Opti.Form 4). The pH of brain heart infusion broth without (control) or with 1.85% PL + 0.13% SDA was adjusted to 5.5, 6.0, 6.5, and 7.5. L. monocytogenes Scott A was inoculated (at 102 CFU/ml) into pH-adjusted broth, which was stored at 4 or 10°C with or without agitation. At pH 5.5, a listeriostatic effect was observed for the broth containing 1.85% PL + 0.13% SDA at 4 and 10°C both with and without agitation. At pH 6.0, 1.85% PL + 0.13% SDA fully controlled the growth of L. monocytogenes Scott A in static broth at 4°C for up to 20 days and significantly slowed the growth of the pathogen in agitated broth. At 10°C, the growth of L. monocytogenes Scott A was significantly reduced by 1.85% PL + 0.13% SDA in agitated and unagitated broths. At pH 6.5, 1.85% PL + 0.13% SDA significantly suppressed the growth of L. monocytogenes Scott A at both 4°C (P < 0.001) and 10°C (P < 0.01). At pH 7.5, 1.85% PL + 0.13% SDA had a limited effect on the growth of L. monocytogenes Scott A in broth stored at 4 and 10°C. At 4°C, agitation decreased the lag time and increased the growth rate of L. monocytogenes Scott A at all tested pHs. A similar but less obvious trend was observed for broths stored at 10°C. These results indicate that lactate-diacetate combinations effectively acted with low pH and temperature to inhibit the growth of L. monocytogenes Scott A.

The Combination of Lactate and Diacetate Synergistically Reduces Cold Growth in Brain Heart Infusion Broth across Listeria monocytogenes Lineages

2010 ◽  
Vol 73 (4) ◽  
pp. 631-640 ◽  
Author(s):  
MATTHEW J. STASIEWICZ ◽  
MARTIN WIEDMANN ◽  
TERESA M. BERGHOLZ
Keyword(s):  
Listeria Monocytogenes ◽  
Synergistic Effects ◽  
Brain Heart Infusion ◽  
Growth Parameter ◽  
Lag Phase ◽  
Minor Effect ◽  
Growth Inhibitors ◽  
Acid Growth ◽  
Potassium Lactate ◽  
Sodium Diacetate

Combinations of organic acids are often used in ready-to-eat foods to control the growth of Listeria monocytogenes during refrigerated storage. The purpose of this study was to quantitatively assess synergy between two organic acid growth inhibitors under conditions similar to those present in cold-smoked salmon, and to assess the effect of evolutionary lineage on response to those growth inhibitors. Thirteen strains of L. monocytogenes, representing lineages I and II, were grown at 7°C in broth at pH 6.1 and 4.65% water-phase NaCl, which was supplemented with 2% potassium lactate, 0.14% sodium diacetate, or the combination of both at the same levels. Our data suggest that lineages adapt similarly to these inhibitors, as the only significant growth parameter difference between lineages was a minor effect (± 0.16 day, P = 0.0499) on lag phase (λ). For all strains, lactate significantly extended λ, from 2.6 ± 0.4 to 3.8 ± 0.5 days (P < 0.001), and lowered the maximum growth rate (μmax) from 0.54 ± 0.06 to 0.49 ± 0.04 log(CFU/ml)/day (P < 0.001), compared with the control. Diacetate was ineffective alone, but in combination with lactate, synergistically increased λ to 6.6 ± 1.6 days (P < 0.001) and decreased μmax to 0.34 ± 0.05 log(CFU/ml)/day (P < 0.001). Monte Carlo simulations provided further evidence for synergy between diacetate and lactate by predicting signficantly slower growth to nominal endpoints for the combination of inhibitors. This study shows potassium lactate and sodium diacetate have significant synergistic effects on both λ and μmax of L. monocytogenes at refrigeration temperature in broth, and justifies combining these inhibitors, at effective levels, in food product formulations.

Control of Growth and Survival of Listeria monocytogenes on Smoked Salmon by Combined Potassium Lactate and Sodium Diacetate and Freezing Stress during Refrigeration and Frozen Storage

2004 ◽  
Vol 67 (11) ◽  
pp. 2465-2471 ◽  
Author(s):  
K. S. YOON ◽  
C. N. BURNETTE ◽  
K. A. ABOU-ZEID ◽  
R. C. WHITING
Keyword(s):  
Listeria Monocytogenes ◽  
Frozen Storage ◽  
Storage Period ◽  
Freezing Stress ◽  
Growth And Survival ◽  
Smoked Salmon ◽  
Potassium Lactate ◽  
Sodium Diacetate ◽  
Kinetics Of ◽  
Different Levels

In this study, we evaluated the antimicrobial effects of different levels of a potassium lactate (PL) plus sodium diacetate (SDA) mixture against the growth and survival of Listeria monocytogenes Scott A inoculated onto smoked salmon stored at 4, 10, and −20°C. The effect of freezing stress on the growth kinetics of L. monocytogenes Scott A on smoked salmon at 4 and 10°C was also investigated. The use of PL+SDA at all tested levels (1.5, 3.3, and 5% of a 60% commercial solution of PURASAL P Opti.Form 4) completely inhibited the growth of L. monocytogenes Scott A on smoked salmon stored at 4°C during 32 days of storage. It also delayed the growth of L. monocytogenes Scott A on smoked salmon stored at 10°C for up to 11 days, but a listeriostatic effect was observed only with 5% PURASAL P Opti.Form 4 at 10°C after 11 days. Addition of PL+SDA at all tested levels decreased the surviving populations of L. monocytogenes Scott A on smoked salmon during 10 months of frozen storage at −20°C. Freezing stress significantly (P < 0.001) extended the lag time and delayed the growth of L. monocytogenes Scott A at both 4 and 10°C. However, the effect of freezing stress was more significant at 4°C than at 10°C, indicating the importance of temperature control of smoked salmon during the retail storage period.

Acid and NaCl Limits to Growth of Listeria monocytogenes and Influence of Sequence of Inimical Acid and NaCl Levels on Inactivation Kinetics

2008 ◽  
Vol 71 (6) ◽  
pp. 1169-1177 ◽  
Author(s):  
LANA SHABALA ◽  
SHIH HUI LEE ◽  
PAULINE CANNESSON ◽  
TOM ROSS
Keyword(s):  
Listeria Monocytogenes ◽  
Water Activity ◽  
High Salinity ◽  
Brain Heart Infusion ◽  
Low Ph ◽  
Inactivation Kinetics ◽  
Limits To Growth ◽  
Significant Difference ◽  
Growth Limits ◽  
Kinetics Of

Variability in growth limits of Listeria monocytogenes in response to low pH (adjusted with HCl) or high salinity (NaCl) was evaluated for 127 strains in brain heart infusion broth at 25°C. Over 95% of strains habituated at pH 5.0 grew subsequently at pH 4.2, while 25% were able to grow at pH 4.1. More than 85% of strains preadapted to growth at 8.5% NaCl (wt/vol) subsequently grew in the presence of 11.3% NaCl, while 25% were able to grow at 13% NaCl, and 4.7% grew in the presence of 13.9% NaCl. The results extend the generally accepted growth limits for L. monocytogenes in response to these hurdles. Two strains, one of which was relatively tolerant of both hurdles, and another that was less tolerant of both hurdles, were subjected to different sequences of lethal acid (pH 3.5) and NaCl (14%, wt/vol) stresses to determine whether survival was affected by growth limits, or by sequence of application of treatment. There was no significant difference in the inactivation kinetics of the two strains, but inactivation rates were affected by different treatments. For both strains, the inactivation rates, from fastest to slowest, resulted from: (i) lethal pH and then by lethal water activity, or lethal water activity and then by lethal pH; (ii) lethal pH and water activity applied simultaneously; (iii) lethal pH; and (iv) lethal water activity. The results demonstrated that the sequence of lethal stress application strongly influences L. monocytogenes inactivation, and that L. monocytogenes growth limits are not good predictors of survival in inimical environments.

Survival and Growth of Listeria monocytogenes in Broth as a Function of Temperature, pH, and Potassium Lactate and Sodium Diacetate Concentrations

2007 ◽  
Vol 70 (11) ◽  
pp. 2620-2625 ◽  
Author(s):  
K. A. ABOU-ZEID ◽  
K. S. YOON ◽  
T. P. OSCAR ◽  
J. G. SCHWARZ ◽  
F. M. HASHEM ◽  
...  
Keyword(s):  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Incubation Temperature ◽  
Lag Time ◽  
Growth Data ◽  
Potassium Lactate ◽  
Survival And Growth ◽  
Sodium Diacetate

The objective of this study was to determine the antimicrobial effect of a combination of potassium lactate and sodium diacetate (0, 1.8, 3, and 4.5%; PURASAL P Opti.Form 4, 60% solution) on the survival and growth of Listeria monocytogenes Scott A in pH-adjusted broth (5.5, 6.0, 6.5, and 7.0) stored at 4, 10, 17, 24, 30, and 37°C. Appropriate dilutions of broth were enumerated by spiral plating on tryptose agar and counted with an automated colony counter. Growth data were iteratively fit, using nonlinear regression analysis to a three-phase linear model, using GraphPad PRISM. At pH 5.5, the combination of lactate-diacetate fully inhibited (P < 0.001) the growth of L. monocytogenes at all four levels and six temperatures. At pH 6.0, addition of 1.8% lactate-diacetate reduced (P < 0.001) the specific growth rate of L. monocytogenes and increased lag time; however, 3 and 4.5% completely inhibited the growth at the six temperatures studied. Efficacy of the lactate-diacetate mixture was decreased as pH increased and incubation temperature increased. Thus, at pH 6.5, at least 3% was required to retard (P < 0.001) the growth of L. monocytogenes in broth. There was a limited effect of the lactate-diacetate level on the specific growth rate of the pathogen at pH 7.0. However, 1.8 and 3% significantly lengthened the lag time at 4 and 10°C. These results suggest that 1.8% of lactate-diacetate mixture can be used as a substantial hurdle to the growth of L. monocytogenes when refrigerated temperatures are maintained for products with pH less than 6.5.

Modeling the Growth Boundary of Listeria monocytogenes in Ready-to-Eat Cooked Meat Products as a Function of the Product Salt, Moisture, Potassium Lactate, and Sodium Diacetate Concentrations

2004 ◽  
Vol 67 (10) ◽  
pp. 2195-2204 ◽  
Author(s):  
J. D. LEGAN ◽  
D. L. SEMAN ◽  
A. L. MILKOWSKI ◽  
J. A. HIRSCHEY ◽  
M. H. VANDEVEN
Keyword(s):  
Listeria Monocytogenes ◽  
Meat Products ◽  
Growth Conditions ◽  
Continuous Variables ◽  
Surface Design ◽  
Potassium Lactate ◽  
Contour Plots ◽  
Sodium Diacetate ◽  
Factor Interactions ◽  
Composite Response

A central composite response surface design was used to determine the time to growth of Listeria monocytogenes as a function of four continuous variables: added sodium chloride (0.8 to 3.6%), sodium diacetate (0 to 0.2%), potassium lactate syrup (60% [wt/wt]; 0.25 to 9.25%), and finished-product moisture (45.5 to 83.5%) in ready-to-eat cured meat products. The design was repeated for ready-to-eat uncured meat products giving a fifth categorical variable for cure status. Products were stored at 4°C. The results were modeled using a generalized regression approach. All five main effects, six two-factor interactions, and two quadratic terms were statistically significant. The model was used to show the boundary between growth and no-growth conditions at 4°C using contour plots of time to growth. It was validated using independent challenge studies of cured and uncured products. Generally, the model predicted well, particularly for cured products, where it will be useful for establishing conditions that prevent the growth of L. monocytogenes. For uncured products, there was good agreement overall between predicted and observed times to growth, but the model is less thoroughly validated than for cured products. The model should initially only be used for screening of formulations likely to prevent growth of Listeria monocytogenes in uncured products, with recommendations subject to confirmation by challenge studies.

scholarly journals Effect of Potassium Lactate and a Potassium Lactate–Sodium Diacetate Blend on Listeria monocytogenes Growth in Modified Atmosphere Packaged Sliced Ham

2007 ◽  
Vol 70 (10) ◽  
pp. 2297-2305 ◽  
Author(s):  
L. A. MELLEFONT ◽  
T. ROSS
Keyword(s):  
Listeria Monocytogenes ◽  
Organic Acid ◽  
Shelf Life ◽  
Storage Temperature ◽  
Modified Atmosphere ◽  
Acid Salt ◽  
Potassium Lactate ◽  
Sodium Diacetate ◽  
Potential Inhibitors ◽  
And Storage

Two commercially available organic acid salts, potassium lactate (PURASAL HiPure P) and a potassium lactate–sodium diacetate blend (PURASAL Opti.Form PD 4), were assessed as potential inhibitors of Listeria monocytogenes growth in modified atmosphere packaged (MAP) sliced ham in challenge studies. The influence of the initial inoculation level of L. monocytogenes (101 or 103 CFU g−1) and storage temperature (4 or 8°C) was also examined. The addition of either organic acid salt to MAP sliced ham strongly inhibited the growth of L. monocytogenes during the normal shelf life of the product under ideal refrigeration conditions (4°C) and even under abusive temperature conditions (i.e., 8°C). During the challenge studies and in the absence of either organic acid salt, L. monocytogenes numbers increased by 1,000-fold after 20 days at 8°C and 10-fold after 42 days at 4°C. Both organic acid salt treatments were found to be listeriostatic rather than listericidal. The addition of either organic acid salt to the MAP ham also reduced the growth of indigenous microflora, i.e., aerobic microflora and lactic acid bacteria. The influence of these compounds on the risk of listeriosis in relation to product shelf life is discussed.

Evaluation of Nisin-Coated Cellulose Casings for the Control of Listeria monocytogenes Inoculated onto the Surface of Commercially Prepared Frankfurters†‡

2004 ◽  
Vol 67 (5) ◽  
pp. 1017-1021 ◽  
Author(s):  
JOHN B. LUCHANSKY ◽  
JEFFREY E. CALL
Keyword(s):  
Listeria Monocytogenes ◽  
Surface Area ◽  
Internal Surface ◽  
Refrigerated Storage ◽  
Internal Surface Area ◽  
Appreciable Increase ◽  
Potassium Lactate ◽  
Selective Agar ◽  
Peptone Water ◽  
Sodium Diacetate

Commercially prepared frankfurters were formulated with and without ~1.4% potassium lactate and 0.1% sodium diacetate and were subsequently processed in cellulose casings coated with and without nisin (~50,000 IU per square inch of internal surface area) to control the outgrowth of Listeria monocytogenes during refrigerated storage. The frankfurters were inoculated with ~5 log CFU per package of a five-strain mixture of L. monocytogenes and then vacuum sealed before being stored at 4° C for 60 to 90 days. Surviving organisms were recovered and enumerated by rinsing each package with 18 ml of sterile 0.1% peptone water and plating onto MOX selective agar. The data for each of two trials were averaged. In packages that contained frankfurters formulated with potassium lactate and sodium diacetate and prepared in nisin-coated casings, L. monocytogenes levels decreased by 1.15 log CFU per package after 90 days of storage. L. monocytogenes levels decreased by 0.95 log CFU per package in frankfurters that were prepared in casings that were not coated with nisin. In packages of frankfurters that were formulated without potassium lactate and sodium diacetate and prepared in nisin-coated casings, L. monocytogenes levels decreased by 0.88 log CFU per package after 15 days of storage but then increased appreciablythereafter over a 60-day period of refrigerated storage. There was also an appreciable increase in pathogen numbers during 60 days of storage in otherwise similar frankfurters formulated without potassium lactate and sodium diacetate prepared in casings that were not coated with nisin. These data confirm that potassium lactate and sodium diacetate display listeriostatic activity as an ingredient of commercial frankfurters. These data also establish that cellulose casings coated with nisin display only moderate antilisterial activity in vacuum-sealed packages of commercially prepared frankfurters during storage at 4° C.

Effects of Suspension in Emulsified Wiener or Incubation in Wiener Packages on the Virulence of Listeria monocytogenes Scott A in Intragastrically Inoculated A/J Mice†

2005 ◽  
Vol 68 (3) ◽  
pp. 597-601 ◽  
Author(s):  
NANCY G. FAITH ◽  
MARK L. TAMPLIN ◽  
DARRELL BAYLES ◽  
JOHN B. LUCHANSKY ◽  
CHARLES J. CZUPRYNSKI
Keyword(s):  
Listeria Monocytogenes ◽  
Gastrointestinal Tract ◽  
Meat Products ◽  
Brain Heart Infusion ◽  
Systemic Infection ◽  
Brain Heart Infusion Broth ◽  
Harsh Environment ◽  
Meat Matrix

Several outbreaks of listeriosis have been associated with contamination of wieners and other ready-to-eat meat products. In this study, we addressed the question of whether emulsification in, or growth on, wieners triggers a response in the listerial cells that makes them more virulent or protects them against the harsh environment of the gastrointestinal tract in mice. Our results indicate that Listeria monocytogenes Scott A grows poorly, if at all, in one brand of commercially prepared wieners inoculated with 5 × 103 to 5 × 106 CFU per package and incubated at 15°C. Neither L. monocytogenes Scott A emulsified in a slurry of homogenized wieners nor recovered from wiener package fluid after a 7-day incubation at 15°C were more virulent when inoculated into the stomachs of A/J mice than L. monocytogenes Scott A grown in brain heart infusion broth. These findings suggest that the ability of L. monocytogenes Scott A to cause systemic infection following introduction into the gastrointestinal tract was not improved by incubation with wieners or suspension in a meat matrix.

Postprocess Control of Listeria monocytogenes on Commercial Frankfurters Formulated with and without Antimicrobials and Stored at 10°C

2006 ◽  
Vol 69 (1) ◽  
pp. 53-61 ◽  
Author(s):  
IFIGENIA GEORNARAS ◽  
PANAGIOTIS N. SKANDAMIS ◽  
KEITH E. BELK ◽  
JOHN A. SCANGA ◽  
PATRICIA A. KENDALL ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Lag Phase ◽  
Potassium Lactate ◽  
Potassium Benzoate ◽  
Sodium Diacetate ◽  
Specific Growth Rates ◽  
Spoilage Microflora ◽  
Antimicrobial Treatments ◽  
Microbiological Analyses ◽  
Different Sources

The antilisterial effect of postprocess antimicrobial treatments on commercially manufactured frankfurters formulated with and without a 1.5% potassium lactate–0.05% sodium diacetate combination was evaluated. Frankfurters were inoculated (ca. 3 to 4 log CFU/cm2) with 10-strain composite Listeria monocytogenes cultures originating from different sources. The inocula evaluated were cells grown planktonically in tryptic soy broth plus 0.6% yeast extract (30°C, 24 h) or in a smoked sausage homogenate (15°C, 7 days) and cells that had been removed from stainless steel coupons immersed in an inoculated smoked sausage homogenate (15°C, 7 days). Inoculated frankfurters were dipped (2 min, 25 ± 2°C) in acetic acid (AA; 2.5%), lactic acid (LA; 2.5%), potassium benzoate (PB; 5%), or Nisaplin (commercial form of nisin; 0.5%, equivalent to 5,000 IU/ml of nisin) solutions, or in Nisaplin followed by AA, LA, or PB, and were subsequently vacuum packaged and stored for 48 days at 10°C. In addition to microbiological analyses, sensory evaluations were performed with uninoculated samples that had been treated with AA, LA, or PB for 2 min. Initial L. monocytogenes populations were reduced by 1.0 to 1.8 log CFU/cm2 following treatment with AA, LA, or PB solutions, and treatments that included Nisaplin reduced initial levels by 2.4 to >3.8 log CFU/cm2. All postprocessing treatments resulted in some inhibition of L. monocytogenes during the initial stages of storage of frankfurters that were not formulated with potassium lactate–sodium diacetate; however, in all cases, significant (P < 0.05) growth occurred by the end of storage. The dipping of products formulated with potassium lactate–sodium diacetate in AA or LA alone—or in Nisaplin followed by AA, LA, or PB—increased lag-phase durations and lowered the maximum specific growth rates of the pathogen. Moreover, depending on the origin of the inoculum, this dipping of products led to listericidal effects. In general, differences in growth kinetics were obtained for the three inocula that were used to contaminate the frankfurters. Possible reasons for these differences include the presence of stress-adapted subpopulations and the inhibition of the growth of the pathogen due to high levels of spoilage microflora. The dipping of frankfurters in AA, LA, or PB did not (P > 0.05) affect the sensory attributes of the product when compared to the control samples. The data generated in this study may be useful to U.S. ready-to-eat meat processors in their efforts to comply with regulatory requirements.

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