Effect of Acidified Sorbate Solutions on the Lag-Phase Durations and Growth Rates of Listeria monocytogenes on Meat Surfaces†

2015 ◽  
Vol 78 (6) ◽  
pp. 1154-1160 ◽  
Author(s):  
CHENG-AN HWANG ◽  
LIHAN HUANG ◽  
VIJAY JUNEJA
Keyword(s):  
Listeria Monocytogenes ◽  
Growth Rates ◽  
Lag Phase ◽  
Factors Affecting ◽  
Response Surface Models ◽  
Cooked Ham ◽  
Surface Models ◽  
Ph Level ◽  
Significant Factors ◽  
Sorbate Concentration

The surfaces of ready-to-eat meats are susceptible to postprocessing contamination by Listeria monocytogenes. This study quantified the lag-phase durations (LPD) and growth rates (GR) of L. monocytogenes on the surfaces of cooked ham as affected by sorbate solutions of different concentrations and pH levels. Slices of cooked ham inoculated with a four-strain mixture of L. monocytogenes (ca. 103 CFU/g) were surface treated with sorbate solutions of 0 to 4% (wt/vol) at pH 4.0 to 6.5, vacuum packaged, and stored at 4 to 12°C for up to 45 days. The LPD and GR of L. monocytogenes were used to develop response surface models. The models estimated that the LPD of L. monocytogenes in samples treated with solutions of pH 4.0 to 5.5 (no sorbate) were 0 to 11 days and the GR were 0.25 to 0.36 log CFU/day, respectively, at 4°C. With the treatments of 2 and 4% (wt/vol) sorbate solutions, the LPD were estimated to be extended to 2 to 26 days and 34 to >45 days, and the GR were reduced to 0.15 to 0.30 and 0 to 0.19 log CFU/day, respectively. At 4°C, increasing sorbate concentrations by 1% (wt/vol) to 2, 3, and 4% (wt/vol) at pH 5.5 to 4.0 led to an extension of LPD by 2 to 11, 10 to 19, and 18 to 27 days, whereas the GR were reduced by 0.037 to 0.055, 0.048 to 0.066, and 0.060 to 0.078 log CFU/day, respectively. Sorbate also extended the LPD and reduced the GR of L. monocytogenes at 8 and 12°C. Results indicated that sorbate concentration and pH level were significant factors affecting the LPD and GR of L. monocytogenes and that the combination of sorbate and low pH has potential for use as a surface treatment to control L. monocytogenes on meat surfaces.

scholarly journals Growth of Listeria monocytogenes in Thawed Frozen Foods

2017 ◽  
Vol 80 (3) ◽  
pp. 447-453 ◽  
Author(s):  
Ai Kataoka ◽  
Hua Wang ◽  
Philip H. Elliott ◽  
Richard C. Whiting ◽  
Melinda M. Hayman
Keyword(s):  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Growth Rates ◽  
Storage Temperature ◽  
Growth Parameters ◽  
Quadratic Model ◽  
Lag Phase ◽  
Frozen Foods ◽  
Phase Duration ◽  
Primary Model

ABSTRACT The growth characteristics of Listeria monocytogenes inoculated onto frozen foods (corn, green peas, crabmeat, and shrimp) and thawed by being stored at 4, 8, 12, and 20°C were investigated. The growth parameters, lag-phase duration (LPD) and exponential growth rate (EGR), were determined by using a two-phase linear growth model as a primary model and a square root model for EGR and a quadratic model for LPD as secondary models, based on the growth data. The EGR model predictions were compared with growth rates obtained from the USDA Pathogen Modeling Program, calculated with similar pH, salt percentage, and NaNO2 parameters, at all storage temperatures. The results showed that L. monocytogenes grew well in all food types, with the growth rate increasing with storage temperature. Predicted EGRs for all food types demonstrated the significance of storage temperature and similar growth rates among four food types. The predicted EGRs showed slightly slower rate compared with the values from the U.S. Department of Agriculture Pathogen Modeling Program. LPD could not be accurately predicted, possibly because there were not enough sampling points. These data established by using real food samples demonstrated that L. monocytogenes can initiate growth without a prolonged lag phase even at refrigeration temperature (4°C), and the predictive models derived from this study can be useful for developing proper handling guidelines for thawed frozen foods during production and storage.

Inhibition of Listeria monocytogenes in Cooked Ham through Active Packaging with Natural Antimicrobials and High-Pressure Processing

2007 ◽  
Vol 70 (11) ◽  
pp. 2498-2502 ◽  
Author(s):  
ANNA JOFRÉ ◽  
MARGARITA GARRIGA ◽  
TERESA AYMERICH
Keyword(s):  
High Pressure ◽  
Listeria Monocytogenes ◽  
Active Packaging ◽  
High Pressure Processing ◽  
The Other ◽  
Lag Phase ◽  
Natural Antimicrobials ◽  
Cooked Ham ◽  
Potassium Lactate

Enterocins A and B and sakacin K at 200 and 2,000 activity units (AU)/cm2, nisin at 200 AU/cm2, 1.8% potassium lactate, and a combination of 200 AU/cm2 of nisin and 1.8% lactate were incorporated into interleavers, and their effectiveness against Listeria monocytogenes spiked in sliced, cooked ham was evaluated. Antimicrobial-packaged cooked ham was then subjected to high-pressure processing (HPP) at 400 MPa. In nonpressurized samples, nisin plus lactate–containing interleavers were the most effective, inhibiting L. monocytogenes growth for 30 days at 6°C, with counts that were 1.9 log CFU/g lower than in the control after 3 months. In the other antimicrobial-containing interleavers, L. monocytogenes did not exhibit a lag phase and progressively grew to levels of about 8 log CFU/g. HPP of actively packaged ham slices reduced Listeria populations about 4 log CFU/g in all batches containing bacteriocins (i.e., nisin, sakacin, and enterocins). At the end of storage, L. monocytogenes levels in the bacteriocin-containing batches were the lowest, with counts below 1.51 log CFU/g. In contrast, HPP moderately reduced L. monocytogenes counts in the control and lactate batches, with populations gradually increasing to about 6.5 log CFU/g at the end of storage.

Evaluating the Growth of Listeria monocytogenes in Refrigerated Ready-to-Eat Frankfurters: Influence of Strain, Temperature, Packaging, Lactate and Diacetate, and Background Microflora

2008 ◽  
Vol 71 (9) ◽  
pp. 1806-1816 ◽  
Author(s):  
AMIT PAL ◽  
THEODORE P. LABUZA ◽  
FRANCISCO DIEZ-GONZALEZ
Keyword(s):  
High Pressure ◽  
Listeria Monocytogenes ◽  
Shelf Life ◽  
Growth Rates ◽  
Maximum Growth ◽  
Lag Time ◽  
Lag Phase ◽  
Potassium Lactate ◽  
Plate Counts ◽  
Data Log

This research was conducted to study the growth of Listeria monocytogenes inoculated on frankfurters stored at different conditions as a basis for a safety-based consume by shelf life date label. Three L. monocytogenes strains were separately inoculated at 10 to 20 CFU/cm2 onto frankfurters that were previously formulated with or without high pressure and with or without added 2% potassium lactate (PL) and 0.2% sodium diacetate (SD). Inoculated frankfurters were air or vacuum packaged; stored at 4, 8, or 12°C; and L. monocytogenes and psychrotrophic plate counts were determined for 90, 60, and 45 days, respectively, or until the stationary phase was reached. The data (log CFU per square centimeter versus time) were fitted using the Baranyi-Roberts model to determine maximum growth rates and lag-phase time. The maximum growth rates and the lag time under each growth condition were used to calculate the time to reach 100-fold the initial Listeria population. In frankfurters lacking PL and SD, the count of all strains increased by 2 log after 18 to 50 days at 4°C and 4 to 13 days at 8°C. The growth was inhibited at 4 and 8°C in frankfurters containing PL and SD, but one ribotype was capable of growing, with the time to reach 100-fold the initial Listeria population ranging from 19 to 35 days at 12°C. In most cases, the time to reach 100-fold the initial Listeria population of L. monocytogenes was significantly longer in vacuum-packaged frankfurters as compared with air-packaged samples. Inclusion of PL and SD also inhibited the growth of psychrotrophs, but at all temperatures the psychrotrophic plate counts were greater than 4 log CFU/cm2 at the end of the experiments. These results indicated that despite the use of antimicrobials, certain L. monocytogenes strains could be capable of growing under storage-abuse conditions. Growth kinetics data could be useful for establishing a shelf life date label protocol under different handling scenarios.

scholarly journals Survival of Unstressed and Acid-, Cold-, and Starvation-Stress-AdaptedListeria monocytogenesin Ham Extract with Hops Beta Acids and Consumer Acceptability of HBA on Ready-to-Eat Ham

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Li Wang ◽  
Cangliang Shen
Keyword(s):  
Growth Rate ◽  
Listeria Monocytogenes ◽  
Sensory Evaluation ◽  
Growth Rates ◽  
Rapid Growth ◽  
Consumer Acceptability ◽  
Lag Phase ◽  
Starvation Stress ◽  
Hedonic Scale ◽  
Lag Phases

The efficacy of hops beta acids (HBA) against unstressed and stress-adaptedListeria monocytogenesin ham extract and the consumers’ acceptability of HBA on ready-to-eat (RTE) hams were investigated. Unstressed or acid-, cold-, or starvation-stress-adaptedL. monocytogeneswas inoculated (1.3–1.5 log CFU/mL) into 10% ham extract, without (control) or with HBA (4.44 or 10.0 µg/mL). Survival/growth of the pathogen during storage (7.2°C, 26 days) was monitored periodically. Sensory evaluation (30 participants, 9-point hedonic scale) was performed with hams dipped into 0.05, 0.11, and 0.23% HBA solution. Ham extracts without HBA supported rapid growth of unstressed and stress-adapted cells with growth rates of 0.39–0.71 log CFU/mL/day and lag phases of 0–3.26 days. HBA inhibited growth of unstressedL. monocytogenesby slowing (P<0.05) growth rate (0.24–0.29 log CFU/mL/day) and increasing (P<0.05) length of the lag phase (3.49–12.98 days) compared to control. Acid-, cold-, or starvation-stress-adapted cells showed cross protection against HBA with greater (P<0.05) growth rates (0.44–0.66 log CFU/mL/day) and similar or shorter lag phases (0–5.44 days) than unstressed cells. HBA did not (P>0.05) affect sensory attributes of RTE ham. These results are useful for RTE meat processors to develop operational protocols using HBA to controlL. monocytogenes.

Validation of Predictive Mathematical Models Describing the Growth of Listeria monocytogenes

1997 ◽  
Vol 60 (9) ◽  
pp. 1142-1145 ◽  
Author(s):  
ISABEL WALLS ◽  
VIRGINIA N. SCOTT
Keyword(s):  
Listeria Monocytogenes ◽  
Growth Rates ◽  
Microbial Growth ◽  
Lag Phase ◽  
Growth Data ◽  
Ph Values ◽  
Gompertz Equation ◽  
Generation Times ◽  
Different Temperatures ◽  
Good Agreement

Growth of Listeria monocytogenes and Listeria innocua in commercially available sterile homogeneous foods was investigated at different temperatures, pH values, and NaCl concentrations. Growth data were fitted to the Gompertz equation and the resulting growth kinetics were compared with predictions from the Pathogen Modeling Program and Food MicroModel. In general, good agreement was obtained when comparing growth rates and generation times for both models. Differences were observed when comparing lag phases, which ranged from 117 h shorter to 4.9 h longer than predicted for L. monocytogenes. Despite differences in lag phase, under most conditions, the models gave good predictions of microbial growth. Predictive modeling appears to be a useful tool in determining growth rates of Listeria in foods.

Effects of Lactic Acid on the Growth Characteristics of Listeria monocytogenes on Cooked Ham Surfaces†

2012 ◽  
Vol 75 (8) ◽  
pp. 1404-1410 ◽  
Author(s):  
CHENG-AN HWANG ◽  
LIHAN HUANG ◽  
SHIOWSHUH SHEEN ◽  
VIJAY JUNEJA
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Storage Temperature ◽  
Meat Products ◽  
Growth Characteristics ◽  
Lag Phase ◽  
Phase Duration ◽  
Cooked Ham ◽  
Root Model ◽  
Significant Extension

The surfaces of ready-to-eat meats are susceptible to postprocessing contamination by Listeria monocytogenes. This study examined and modeled the growth characteristics of L. monocytogenes on cooked ham treated with lactic acid solutions (LA). Cooked ham was inoculated with L. monocytogenes (ca. 103 CFU/g), immersed in 0, 0.5, 0.75, 1.0, 1.25, 1.5, and 2.0% LA for 30 min, vacuum packaged, and stored at 4, 8, 12, and 16°C. LA immersion resulted in &lt;0.7 log CFU/g immediate reduction of L. monocytogenes on ham surfaces, indicating the immersion alone was not sufficient for reducing L. monocytogenes. During storage, no growth of L. monocytogenes occurred on ham treated with 1.5% LA at 4 and 8°C and with 2% LA at all storage temperatures. LA treatments extended the lag-phase duration (LPD) of L. monocytogenes and reduced the growth rate (GR) from 0.21 log CFU/day in untreated ham to 0.13 to 0.06 log CFU/day on ham treated with 0.5 to 1.25% LA at 4°C, whereas the GR was reduced from 0.57 log CFU/day to 0.40 to 0.12 log CFU/day at 8°C. A significant extension of the LPD and reduction of the GR of L. monocytogenes occurred on ham treated with &gt;1.25% LA. The LPD and GR as a function of LA concentration and storage temperature can be satisfactorily described by a polynomial or expanded square-root model. Results from this study indicate that immersion treatments with &gt;1.5% LA for 30 min may be used to control the growth of L. monocytogenes on cooked meat, and the models would be useful for selecting LA immersion treatments for meat products to achieve desired product safety.

scholarly journals Plant Extracts for the Control of Listeria monocytogenes in Meat Products

2021 ◽  
Vol 11 (22) ◽  
pp. 10820
Author(s):  
Simona de Niederhäusern ◽  
Moreno Bondi ◽  
Stefania Camellini ◽  
Carla Sabia ◽  
Patrizia Messi ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Plant Extracts ◽  
Meat Products ◽  
Antagonistic Activity ◽  
Viable Count ◽  
Lag Phase ◽  
Pathogen Elimination ◽  
Initial Reduction ◽  
Allium Cepa L ◽  
Cooked Ham

The antimicrobial activity of garlic (Allium sativum L.) and onion (Allium cepa L.) plant active extracts was determined against Listeria monocytogenes in two meat products. Samples of sausages “cacciatore” and cooked ham in vacuum-packaged slices were artificially contaminated, and the presence of Listeria was evaluated during the sausages ripening and throughout the shelf-life of the cooked ham. The test carried out on sausages did not show differences among treated and untreated samples. The antagonistic activity of the plant extracts against the pathogen was probably hidden by the competition from the sausages microbial flora and the pH and the water activity (aw) decrease. On the other hand, the plant extracts determined an initial reduction of about 1.00 log cfu/g of the L. monocytogenes viable count in the cooked ham slices contaminated with 103 cfu/g, but the best result was obtained with the contamination of 102 cfu/g of L. monocytogenes. In addition to the pathogen’s initial decrease, we observed an extension of the lag phase and a reduction of the Listeria growth rate. Considering that the presence of L. monocytogenes during the slicing phase of the cooked ham does not exceed 10 cfu/g, the use of plant extracts can lead to complete pathogen elimination.

Elemental chlorine-free bleaching of North American hardwood kraft pulps: Evaluation of oxidant-reinforced extraction variables on overall bleaching optimization

TAPPI Journal ◽  
2013 ◽  
Vol 12 (10) ◽  
pp. 33-41 ◽  
Author(s):  
BRIAN N. BROGDON
Keyword(s):  
Response Surface ◽  
Chlorine Dioxide ◽  
North American ◽  
Yield Loss ◽  
Alkaline Extraction ◽  
Kraft Pulps ◽  
Pulp Bleaching ◽  
Response Surface Models ◽  
Elemental Chlorine ◽  
Surface Models

This investigation evaluates how higher reaction temperatures or oxidant reinforcement of caustic extraction affects chlorine dioxide consumption during elemental chlorine-free bleaching of North American hardwood pulps. Bleaching data from the published literature were used to develop statistical response surface models for chlorine dioxide delignification and brightening sequences for a variety of hardwood pulps. The effects of higher (EO) temperature and of peroxide reinforcement were estimated from observations reported in the literature. The addition of peroxide to an (EO) stage roughly displaces 0.6 to 1.2 kg chlorine dioxide per kilogram peroxide used in elemental chlorine-free (ECF) bleach sequences. Increasing the (EO) temperature by Δ20°C (e.g., 70°C to 90°C) lowers the overall chlorine dioxide demand by 0.4 to 1.5 kg. Unlike what is observed for ECF softwood bleaching, the presented findings suggest that hot oxidant-reinforced extraction stages result in somewhat higher bleaching costs when compared to milder alkaline extraction stages for hardwoods. The substitution of an (EOP) in place of (EO) resulted in small changes to the overall bleaching cost. The models employed in this study did not take into account pulp bleaching shrinkage (yield loss), to simplify the calculations.

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