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This study was conducted to evaluate antilisterial activity in deli-style turkey using one of the inhibitors: hop α- or β-acids at 5 ppm, potassium acetate/potassium diacetate (PAPD) at 0.5%, their combinations, potassium lactate/sodium diacetate (PLSD) at 2.5% for positive control, and ethanol at 5 ppm for negative control. Deli-style turkey was formulated and manufactured traditionally. To simulate Listeria contamination in processing plants, the deli turkey was sliced in24 h of production, inoculated with Listeria monocytogenes (2 to 3 log CFU/g), and vacuum-stored at 4 or 7°C for 60 d. To simulate Listeria contamination in grocery stores, the deli turkey was vacuum-stored for 30 and 60 d prior to slicing, inoculation, and aerobic storage at 4 or 7°C for 10 d. Physicochemical properties of the deli turkey were not significantly different among treatments (P0.05). Addition of hop acids at 5 ppm did not inhibit Listeria in deli meat during 60 d of vacuum-storage at 4 or 7°C, whereas organic acids and hop acids/PAPD significantly inhibited Listeria (P0.05), with the best inhibition observed for hop β-acids/PAPD at 7°C/60 d. During 10 d of aerobic storage at 4°C, hop acid/PAPD, PLSD, or PAPD showed listeristatic effects, whereas hop acids alone allowed Listeria to grow by 0.9 CFU/g. During 10 d of aerobic storage at 7°C, hop acid/PAPD, PLSD, and PAPD significantly reduced Listeria populations than hop α-acids, β-acids, and no-inhibitor control (P0.05). These results indicated the combination of hop β-acids/PAPD provides more effective inhibition than any single addition of hop acids and PLSD (P0.05) at 7°C/60 d in vacuum storage, with intermediate inhibition observed for PAPD and α-acids/PAPD.

Listeria monocytogenes is a food-borne pathogen often associated with ready-to-eat (RTE) food products. Many antimicrobial compounds have been evaluated in RTE meats. However, the search for optimum antimicrobial treatments is ongoing. The present study developed a rapid, non-destructive preliminary screening tool for large-scale evaluation of antimicrobials utilizing a bioluminescent L. monocytogenes with a model meat system. Miniature hams were produced, surface treated with antimicrobials nisin (at 0&ndash, 100 ppm) and potassium lactate sodium diacetate (at 0&ndash, 3.5%) and inoculated with bioluminescent L. monocytogenes. A strong correlation (r = 0.91) was found between log scale relative light units (log RLU, ranging from 0.00 to 3.35) read directly from the ham surface and endpoint enumeration on selective agar (log colony forming units (CFU)/g, ranging from 4.7 to 8.3) when the hams were inoculated with 6 log CFU/g, treated with antimicrobials, and L. monocytogenes were allowed to grow over a 12 d refrigerated shelf life at 4 &deg, C. Then, a threshold of 1 log RLU emitted from a ham surface was determined to separate antimicrobial treatments that allowed more than 2 log CFU/g growth of L. monocytogenes (from 6 log CFU/g inoculation to 8 log CFU/g after 12 d). The proposed threshold was utilized in a luminescent screening of antimicrobials with days-to-detect growth monitoring of luminescent L. monocytogenes. Significantly different (p &lt, 0.05) plate counts were found in antimicrobial treated hams that had reached a 1 log RLU increase (8.1&ndash, 8.5 log(CFU/g)) and the hams that did not reach the proposed light threshold (5.3&ndash, 7.5 log(CFU/g)). This confirms the potential use of the proposed light threshold as a qualitative tool to screen antimicrobials with less than or greater than a 2 log CFU/g increase. This screening tool can be used to prioritize novel antimicrobials targeting L. monocytogenes, alone or in combination, for future validation.

All-pork mortadella, an Italian-style deli meat, was produced by a local artisanal meat producer with or without 1.0 or 1.5% liquid buffered vinegar (LBV), 0.4, 0.6, or 1.0% dry buffered vinegar (DBV), or a 2.5% blend of potassium lactate and sodium diacetate (KLac). In each of three trials, mortadella was sliced (ca. 1.5 cm thick, ca. 30 g) and surface inoculated with 250 μL per side of a five-strain mixture of Listeria monocytogenes (ca. 3.8 log CFU per slice). The packages were vacuum sealed and then stored at 4 or 12°C. In the absence of antimicrobials, L. monocytogenes levels increased by ca. 2.6 and 6.0 log CFU per slice after up to 120 or 28 days at 4 or 12°C, respectively. With inclusion of 1.0 or 1.5% LBV, 1.0% DBV, or 2.5% KLac as ingredients, pathogen levels decreased by ca. 0.3 to 0.7 log CFU per slice after 120 days at 4°C, whereas with inclusion of 0.4 or 0.6% DBV, L. monocytogenes levels increased by ca. 1.2 and 0.8 log CFU per slice, respectively. After 28 days at 12°C, inclusion of 2.5% KLac, 1.0 or 1.5% LBV, or 0.4 or 0.6% DBV resulted in a ca. 1.4- to 5.7-log increase in L. monocytogenes levels. When 1.0% DBV was included in the formulation, pathogen levels remained unchanged after 28 days at 12°C. However, product quality was lessened at this abusive storage temperature (12°C) for all treatments by the end of storage. Thus, inclusion of LBV or DBV, as clean-label ingredients, in mortadella is equally effective as KLac for controlling L. monocytogenes during storage at 4°C without adversely affecting product quality.

Background: One of the most important health challenges is to deal with infectious diseases due to their high prevalence. Since resistance of pathogens to antimicrobial compounds is rising, more studies are performed to develop new antimicrobial agents. Herbs are one of the best sources to achieve the goal. Objectives: The current study aimed at examining the possible antibacterial activity of the barberry root and fennel seed extracts individually and in combination with sodium diacetate and nisin against Escherichia coli O157:H7. Methods: Extract of the barberry root and fennel seed were prepared by soaking in ethanol 80% and analyzed by high-performance thin-layer chromatography and gas chromatography-mass spectrometry, respectively. Antimicrobial activity of the extracts was detected by disk diffusion and broth microdilution methods in triplicate. Results: Nisin showed the highest antibacterial activity against E. coli O157:H7 followed by the extracts of barberry root and fennel seed, and sodium diacetate. The data were consistent with the results of the disk diffusion test. Moreover, a significant difference was observed between antibacterial activity of nisin and sodium diacetate individually, and in combination with the extracts. Conclusions: The results of the current study showed that the inhibitory effects of sodium diacetate and nisin combined with barberry root and fennel seed extracts were higher compared to their individual effects; it leads to the application of lower amounts of sodium diacetate and nisin in combination with herbal extracts and highly prevents their individual side effects such as toxicity and organoleptic changes.

The antilisterial activity of sodium diacetate and a commercial shelf-life extender (ALTA™ 2341) were monitored at 25°C in slurries prepared with turkey breast meat. In slurries prepared without either ingredient, populations of Listeria monocytogenes increased about 5-log10 units in 7 d. The addition of 0.3% diacetate extended the generation time (7 h) compared to the control (no food additives; 1.7 h), whereas 0.5% inhibited the pathogen somewhat (0.4-log10 unit decrease in 7 d compared to the control). Slurries containing ALTA (0.25, 0.5, or 0.75%) and 0.3% diacetate extended the lag phase of L. monocytogenes to a greater extent than slurries with 0.3% diacetate alone. In contrast, 0.5% diacetate in combination with all three levels of ALTA tested was listericidal (ca. 2-log10 unit decrease after 7 d compared to the control). These data confirm the efficacy of diacetate for inhibiting L. monocytogenes in turkey meat and indicate that multiple barriers such as diacetate with ALTA may further lessen the likelihood of food-related listeriosis.

The antimicrobial activity of essential oils (EOs), organic acid (OA) salts and natamycin, a natural antifungal produced during fermentation by the bacterium Streptomyces natalensis , was assessed against four pathogens ( Escherichia coli O157:H7, Listeria monocytogenes , Salmonella Typhimurium and Aspergillus niger ). The Minimum Inhibitory Concentration (MIC) of each antimicrobial (AM) was assessed to determine their efficiency on tested microbial species in order to select the most efficient. Then, the interactions between different antimicrobial compounds showing the lowest MIC were determined by the checkerboard method. The most effective antimicrobial formulation showing synergistic or additive effects was then encapsulated in an alginate matrix to protect the antimicrobial efficiency during storage. The effectiveness of the formulation was then evaluated in situ using broccoli as a food model. A combined treatment of active coating and γ-irradiation (0.4 and 0.8 kGy) was also done in order to evaluate the possible synergistic effect between treatments. The results of this study allowed the selection of 4 EOs, one OA salt and the natamycin as an antifungal agent exhibiting lower MIC values. The interactive antimicrobial effects between them showed that an antimicrobial formulation composed of 300 ppm of lemongrass EO, 5000 ppm of sodium diacetate and 80 ppm of natamycin resulted in an additive effect against A. niger , E. coli and S. Typhimurium and showing synergistic effect against L. monocytogenes . Finally, in situ analyses showed a synergistic antimicrobial activity between active coating and γ-irradiation and allowed the extension of the shelf-life of ready-to-eat (RTE) broccoli during storage at 4 °C.

Fresh walnuts deteriorate and develop mold rapidly during cold storage. The effects of chlorine dioxide (ClO2) and sodium diacetate (SDA) in controlled atmosphere (CA) storage on deterioration of fresh walnuts have been investigated. 'Xifu No.1′ fresh walnuts were treated with air (Control), air +200 mg kg−1 sodium diacetate (SDA), air +50 mg L−1 chlorine dioxide (ClO2), 2 % O2 + 25 % CO2 (CA), CA + SDA and CA + ClO2 and then stored at 0 ± 1 °C for 135 d. Mold incidence, nutrient quality, oil quality and physiological indices of the walnuts were analyzed. The results showed that CA, CA + SDA, CA + ClO2 treatments delayed the development of mold, increased POD activity while decreasing PPO activity, and maintained quality of fresh walnuts in comparison to air treatments. CA + SDA and CA + ClO2 maintained higher melatonin content and lower peroxide and carbonyl values of fresh walnuts than CA treatment alone, but no difference in mold incidence were detected between CA and CA + SDA treatments. Overall, CA + ClO2 was the optimal treatment and kept quality of fresh walnuts for 135d at 0 ± 1 °C, with the lowest mold incidence (5 %), the highest firmness and contents of fat and melatonin, as well as the maximum POD activity.

We evaluated the efficacy of potassium levulinate (KLEV; 0.0, 1.0, 1.5, and 2.0%) with and without a blend of potassium propionate (0.1%) and potassium diacetate (0.1%) (KPD) versus a blend of potassium lactate (1.8%) and sodium diacetate (0.125%) (KLD) for inhibiting Listeria monocytogenes on commercially prepared, uncured turkey breast during refrigerated storage. Product formulated with KLD or KLEV (1.5%) was also subsequently surface treated with 44 ppm of a solution of lauric arginate (LAE). Slices (ca. 1.25 cm thick and 100 g) of turkey breast formulated with or without antimicrobials were surface inoculated on both the top and bottom faces to a target level of ca. 3.5 log CFU per slice with a five-strain cocktail of L. monocytogenes, vacuum sealed, and then stored at 4°C for up to 90 days. Without inclusion of antimicrobials in the formulation, pathogen levels increased by ca. 5.2 log CFU per slice, whereas with the inclusion of 1.0 to 2.0% KLEV pathogen levels increased by only ca. 2.9 to 0.8 log CFU per slice after 90 days at 4°C. When 1.0% KLEV and KPD were included as ingredients, pathogen levels increased by ca. 0.8 log CFU per slice after storage at 4°C for 90 days, whereas a decrease of ca. 0.7 log CFU per slice was observed when 1.5 or 2.0% KLEV and KPD were included as ingredients. When used alone, KPD was not effective (≥5.8-log increase). As expected, KLD was effective at suppressing L. monocytogenes in uncured turkey breast. When uncured turkey breast was formulated with KLD or KLEV (1.5%) or without antimicrobials and subsequently surface treated with LAE, pathogen levels decreased by ca. 1.0 log CFU per package within 2 h; no differences (P ≥ 0.01) were observed in pathogen levels for product surface treated with or without LAE and stored for 90 days. Our results validate the use of KLEV to inhibit outgrowth of L. monocytogenes during refrigerated storage of uncured turkey breast. KLEV is at least as effective as KLD as an antilisterial agent.

The effectiveness of rosemary and thyme oils as antimicrobial agents in mozzarella cheese against Listeria monocytogenes, lactic acid bacteria (LAB), and total aerobic bacteria (TAB) was evaluated. In low fat cheese, rosemary and thyme oils inhibited L. monocytogenes by 0.5 and 1.0 log CFU/g, respectively, and by 1.7 log CFU/g in combination on day 20 at 4°C. Combination of rosemary and thyme oils inhibited growth of L. monocytogenes and LAB in low fat cheese, but not in full fat cheese. Rosemary and thyme oils with sodium diacetate were more effective for inhibition of L. monocytogenes than oil alone. Essential oils have potential applications for inhibition of indigenous microorganisms in low fat food products, and for controlling growth of L. monocytogenes after post-processing contamination. The oils also showed potential for inhibition of microorganisms in full fat products in combination with sodium diacetate.

The aim of the present study was to understand growth and survival responses of Listeria monocytogenes during the storage of high pressure processed (HPP) cooked ham formulated with organic acids to inhibit growth of the pathogen. Cooked ham batches were manufactured without organic acids (control), with potassium lactate (2.8% or 4%) or with potassium lactate and sodium diacetate (2.0% + 0.11% or 2.0% + 0.45%). Products were aseptically sliced and inoculated with 107 cfu/g or 102 cfu/g of either L. monocytogenes CTC1034 (a meat isolate) or a cocktail of three isolates (12MOB045Lm, 12MOB089Lm and Scott A). Vacuum-packed samples with 107 cfu/g were HPP at 600 MPa for 3 min, whereas samples with 102 cfu/g were not HPP. Growth or survival of L. monocytogenes was determined during subsequent storage at 8, 12 and 20 °C. Growth or survival was characterized by fitting the experimental data using the primary logistic model and the log-linear with shoulder model, respectively. Secondary models were fitted to characterize the effect of temperature on growth kinetic parameters without or with HPP. For cooked ham without organic acids, growth rates of L. monocytogenes were slightly increased by HPP and lag times were longer. Interestingly, for cooked ham with organic acids, the HPP had a significant stimulating effect on subsequent growth of L. monocytogenes (piezo-stimulation). At 20 °C, the growth rates of L. monocytogenes in cooked ham with lactate were up to 4-fold higher than those of the same product without HPP. The observed enhancement of the piezo-stimulating effect of organic acids on growth rates during storage of HPP cooked ham represents a challenge for the use of organic acids as antimicrobials in these products. A predictive model available as part of the Food Spoilage and Safety Predictor (FSSP) software seemed useful to predict growth and growth boundary of L. monocytogenes in non-pressurised cooked ham. This model was calibrated to take into account the observed piezo-stimulating effect and to predict growth of L. monocytogenes in HPP cooked ham with organic acids. info:eu-repo/semantics/acceptedVersion

The antimicrobial effect of spice-based marinades against Campylobacter jejuni on inoculated fresh broiler wings was investigated. Experiments were carried out with 1 strain of C. jejuni and 6 marinades. Four experimental marinades were composed for the study and contained spices (thyme, rosemary, basil, marjoram, and so on) and different combination of bioactive compounds. Two marinades were commercial and contained spices (black pepper, sweet red pepper, and so on) and chemical additives (monosodium glutamate, sodium diacetate, calcium lactate), 1 commercial marinade was also enriched with bioactive compounds (linalool, cinnamaldehyde, lactic acid). Total aerobic bacterial count was examined to estimate the possible effect of tested marinades on the shelf-life of marinated broiler wings. Study revealed that thyme-based marinade was the most effective against C. jejuni on broiler wings and reduced the numbers of campylobacters by 1.04 log colony forming unit (CFU)/g (P ≤ 0.05) during storage for 168 h at 4 °C temperature. Moreover, it was more effective against C. jejuni than commercial marinade with 0.47 log CFU/g (P ≤ 0.05) reduction effect. Both experimental and commercial marinades had very similar effect on the total aerobic bacterial count. Although experimental and commercial marinades had different effect on pH of broiler wings, this parameter did not show a major impact on the antimicrobial effect of tested marinades (P ≥ 0.05). Our study shows that experimental natural thyme-based marinade can reduce numbers of C. jejuni more effectively than tested commercial marinades. Practical Application Experimental spice-based marinades could be used for marinating broiler meat to ensure the enhanced safety of contaminated broiler meat by reducing Campylobacter jejuni counts. Thyme-based and rosemary-based marinades may reduce public health risk to acquire campylobacteriosis through miss-handling and consumption of marinated broiler meat and satisfy consumers demand for more natural broiler meat products.

Cytotoxicity and genotoxicity of sodium acetate (SA), sodium diacetate (SDA), and potassium sorbate (PS) was tested on Human Umbilical Vein Endothelial Cells (HUVEC). Cytotoxicity was investigated by MTT assay and flow cytometry analysis, while genotoxicity was evaluated using DNA fragmentation and DAPI staining assays. The growth of treated HUVECs with various concentrations of SA, SDA and PS decreased in a dose-and time-dependent manner. The IC50 of 487.71, 485.82 and 659.96 µM after 24 h and IC50 of 232.05, 190.19 and 123.95 µM after 48 h of treatment were attained for SA, SDA and PS, respectively. Flow cytometry analysis showed that early and late apoptosis percentage in treated cells was not considerable. Also neither considerable DNA fragmentation nor DNA smear was observed using DAPI staining and DNA ladder assays. Overall, it can be concluded that the aforementioned food additives can be used as safe additives at low concentration in food industry.

Laminaria japonica Aresch as a medicine and food dual-purpose economical marine algae in China, has been gradually accepted by people. Combining staple food with kelp function ingredients has practical value. The effects of mannitol, alginate and peptides from kelp on rheological properties, texture and preservatives of noodles were investigated. Results of rheological properties and texture showed that the addition of peptides, mannitol and alginate enhanced storage modulus (G′), loss modulus (G″) and elasticity of dough. Protein secondary structure was as follows: β-turns > β-sheets > α-helices > random coil. Moreover, the α-helix content was increased from 1.52-fold to 1.95-fold while β-turn content was decreased from 0.77% to 5.10% relative to blank group. When 0.04% of DHA-S (Sodium dehydroacetate), 0.05% of SDA (Sodium diacetate) and 0.05% of the GMC (Glycerol monocaprylate) were added to wet-fresh noodles, the noodles could be preserved for 50.12 h at 28 °C.

This study investigated the antimicrobial effects of rooibos (tea extract), potassium lactate (PL) and sodium diacetate (SDA) mixture alone or in combinations on the growth of Clostridium perfringens vegetative cell and spore in ready-to-eat (RTE) Jokbal (pig's trotters). Addition of a combination of 10% rooibos and 4% PL + SDA inhibit growth of C. perfringens vegetative cell in Jokbal at 24 °C and 36 °C. The significant inhibition on germination and growth of C. perfringens spores was also observed in Jokbal with a combination of 10% rooibos and 4% PL + SDA (PL: 2.24%, SDA: 0.16%) at 24 °C. The Jokbal treated with 10% rooibos and 4% PL + SDA mixture had significantly (P < 0.05) lower TBARS values than the control at 10 and 24 °C. The lipid oxidation inhibition effect was the highest (P < 0.05) in anaerobic packed Jokbal with 10% rooibos. The addition of a combination of 10% rooibos and 4% PL + SDA during the processing of Jokbal prevented the growth of C. perfringens and the germination and growth of C. perfringens spores at room temperature. This study shows rooibos tea as a valuable natural food preservative in meat products. Practical Application The growth of Clostridium perfringens and the germination and growth of C. perfringens spores are prevented in ready-to-eat Jokbal (Pig's trotter) treated with a combination of rooibos and PL + SDA at room temperature. Rooibos extract is very effective to inhibit lipid oxidation in the anaerobic packed Jokbal. This study presents rooibos tea as a useful natural food preservative in meat product.

Contamination of cold-smoked salmon by Listeria monocytogenes is a major concern for the seafood industry. The objectives of this study were to (i) determine the most effective bactericidal treatment for L. monocytogenes on salmon and (ii) optimize bactericidal and bacteriostatic treatment combinations to identify cost-effective treatments against L. monocytogenes on salmon. L. monocytogenes challenge trials were conducted in brain heart infusion (BHI) and on salmon disks that were supplemented with bactericidal compounds nisin (NIS), lauric arginate (LAE), e-polylysine (EPL), and chitosan (CHIT). Subsequently, the most effective bactericidal compound was further tested by concurrent application of a blend of organic acid salts containing potassium lactate and sodium diacetate (PLSDA). L. monocytogenes populations were measured at 7 °C over 60 days, and initial cell density ( N 0 ), maximum initial log reduction ( N r ), lag phase (λ), maximum growth rate (μ max ), and maximum cell density ( N max ) over 60 days storage were estimated. Time to recover to initial cell density ( T initial ) was also compared for combinations of bactericidal and bacteriostatic treatments. Varying degrees of antimicrobial effects were observed with bactericidal compounds in BHI. However, when tested on salmon, only NIS significantly decreased initial L. monocytogenes populations by approximately 2 log CFU/g, and reduced N max by approximately 1.5 log CFU/g compared to untreated control (CTRL). N r achieved by the combined treatment of NIS and PLSDA was approximately 2 log CFU/g regardless of the presence of PLSDA, and a dose-dependent increase in N r was observed with increasing NIS concentrations. PLSDA alone or in combination with 20 ppm NIS was most effective at delaying growth of L. monocytogenes . The greatest reduction in N max was observed with the combination of 20 ppm NIS and PLSDA; N max was 3.1 log CFU/g lower compared to CTRL. Comparison of T initial indicated that PLSDA with NIS can effectively retard growth of L. monocytogenes to its initial level (following initial reduction) and offers a cost benefit over using high concentrations of NIS alone. In summary, the combined application of NIS (for a bactericidal effect) and PLSDA (for a bacteriostatic effect) proved to be an effective treatment option to reduce initial levels as well as minimize subsequent growth of L. monocytogenes throughout the expected shelf-life of cold-smoked salmon.

The objective of this study was to evaluate anti-listerial efficacy of salts of organic acids, and their impact on the quality of frankfurters. Beef frankfurters were manufactured by incorporating organic acids in 5 different combinations: (1) control (no marinade addition; C); (2) sodium lactate (2% wt/wt; SL); (3) potassium lactate (2% wt/wt; PL); (4) sodium citrate (0.75% wt/wt; SC); and (5) sodium lactate (2% wt/wt)/sodium diacetate (0.25% wt/wt; SL/SD). Cooked frankfurters were inoculated with streptomycin-resistant (1500 μg/mL) L. monocytogenes (7 log₁₀ CFU/frank). Inoculated and noninoculated frankfurters were vacuum packaged and stored at 4 °C. Samples were taken weekly up to 10 wk for estimation of L. monocytogenes as well as aerobic plate count (APC) and psychrotrophs (PSY), respectively. Total of 2 independent trials of the entire experiment were conducted. Noninoculated beef frankfurters were evaluated weekly by untrained sensory panelists for 7 wk. SL, PL, and SC treatments did not (P > 0.05) adversely affect consumer acceptability through 8 wk although, SL/SD treatment was significantly (P ≤ 0.05) less preferred across all sensory attributes. SL/SD treatment negatively affected product quality, but was able to control APC, PSY, and L. monocytogenes levels. SC performed similar to the control throughout the 8, 9, and 10 wk storage periods, providing no benefit for inhibiting L. monocytogenes (increasing from 7 logs CFU/frank to 10 logs CFU/frank throughout storage) or extending shelf life of the beef frankfurters. In conclusion, 2% SL and PL, and 2% SL/0.25% SD may be effective L. monocytogenes inhibitors (maintaining inoculation levels of 7 logs CFU/frank during storage), but changes in SL/SD treatment formulation should be studied to improve product quality.

The aim of this study was to verify the effectiveness of the commercially available anti-Listeria phage preparation LISTEX(™)P100 in reducing Listeria monocytogenes on ready-to-eat (RTE) roast beef and cooked turkey in the presence or absence of the chemical antimicrobials potassium lactate (PL) and sodium diacetate (SD). Sliced RTE meat cores at 4 and 10 °C were inoculated with cold-adapted L. monocytogenes to result in a surface contamination level of 10(3)CFU/cm(2). LISTEX(TM)P100 was applied at 10(7) PFU/cm(2) and samples taken at regular time intervals during the RTE product's shelf life to enumerate viable L. monocytogenes. LISTEX(™)P100 was effective during incubation at 4 °C with initial reductions of L. monocytogenes of 2.1 log10 CFU/cm(2) and 1.7 log10 CFU/cm(2), respectively, for cooked turkey and roast beef without chemical antimicrobials (there was no significant difference to the initial L. monocytogenes reductions in the presence of LISTEX(TM)P100 for cooked turkey containing PL and roast beef containing SD-PL). In the samples containing no chemical antimicrobials, the presence of phage resulted in lower L. monocytogenes numbers, relative to the untreated control, of about 2 log CFU/cm(2) over a 28-day storage period at 4 °C. An initial L. monocytogenes cell reduction of 1.5 log10 CFU/cm(2) and 1.7 log10 CFU/cm(2), respectively, for cooked turkey and roast beef containing no chemical antimicrobials was achieved by the phage at 10 °C (abusive temperature). At this temperature, the L. monocytogenes cell numbers of samples treated with LISTEX™ P100 remained below those of the untreated control only during the first 14 days of the experiment for roast beef samples with and without antimicrobials. On day 28, the L. monocytogenes numbers on samples containing chemical antimicrobials and treated with LISTEX(TM)P100 stored at 4 and 10 °C were 4.5 log10 CFU/cm(2) and 7.5 log10 CFU/cm(2), respectively, for cooked turkey, and 1.2 log10 CFU/cm(2) and 7.2 log10 CFU/cm(2), respectively, for roast beef. In both cooked turkey samples with and without chemical antimicrobials stored at 10 °C, the phage-treated samples had significantly lower numbers of L. monocytogenes when compared to the untreated controls throughout the 28-day storage period (P

An experiment was conducted to investigate the effect of acid-binding capacity (ABC) and acidifiers in different basal diets on leg bones of broilers at 21 and 41 days of age. In a 3 × 2 × 2 factorial experiment, three levels of ABC (650, 800, and 950 mEq/kg), two mixes of acidifiers (fumaric acid and sodium diacetate and tartaric acid and calcium propionate), and two types of basal diet (optimal diet based on corn and suboptimal diet based on wheat–corn without enzyme) were assessed. Wheat–corn diet containing 650 mEq/kg ABC and tartaric acid caused the most density of femur, but fumaric acid resulted in the lowest density as compared with the other treatments at 21 days. The combination of fumaric acid and calcium carbonate improved bone density and ash percentage of tibia at 21 days. Tibia of chickens fed corn diet containing 650 mEq/kg ABC and fumaric acid had the highest density but with tartaric acid had the lowest density as compared with the other dietary treatments. However, the main effects and their interactions were not pronounced on weight, volume, and length of tibia at 21 days. Wheat–corn diet and 950 mEq/kg ABC significantly decreased phosphorus content of serum. However, the other factors and their interactions did not affect the phosphorus and calcium content of serum at 41 days. In histological traits of tibia, corn diet as compared with wheat–corn diet increased the height of proliferative zone but did not affect the hypertrophic and mineralized zones at 21 days. Tartaric acid as compared with fumaric acid significantly increased hypertrophic and mineralized zones but did not affect the proliferative zone at 21 days. The ABC at the level of 950 mEq/kg ABC significantly increased the height of hypertrophic zone but decreased proliferative and mineralized zones at 21 days. These factors and their interactions did not affect any zones of growth plate of tibia at 41 days.

Queso fresco, is a Hispanic non-fermented cheese highly susceptible to contamination with L. monocytogenes. This research was aimed to determine the effect of GRAS antimicrobial ingredients to control L. monocytogenes. Antimicrobials included caprylic acid (CA), Nisaplin® (N, 2.5% nisin), a mixture of sodium lactate and sodium diacetate (SL/SD), Lactococcus lactis sbp. lactis DPC 3147, monolaurin, and lactic acid (LA). Batches of queso fresco curds were inoculated with 104 CFU/g and stored at 4 °C for three weeks. During storage the count of L. monocytogenes reached 7 to 8 Log CFU/g in control samples. Most individual antimicrobial treatments resulted in less than 1 Log CFU/g reductions in final counts, with the exception of N (0.5 g/kg) and CA (2.9 g/kg) that caused more than 3 and 5 Log CFU/g differences with controls, respectively. Mixtures of ingredients were more effective in inhibiting L. monocytogenes growth, and treatments with N and CA consistently delivered 6 Log CFU/g less counts than controls. Supplementation of 12 g/kg LA to treatments with SL/SD (3%/0.22%) caused differences of more than 4 Log CFU/g in final Listeria populations. Samples treated with the binary mixtures of N and CA (0.5 and 0.7 g/kg, respectively) were evaluated in a consumer panel (n = 67). Panelists slightly preferred control and commercial over treated samples, but all samples were in average rated between “slightly liking” and “moderately liking.” These experiments indicated that combined use of antimicrobial ingredients may be an effective way to control the population of Listeria monocytogenes in queso fresco.

This study evaluated dipping solutions of lyophilized cell-adsorbed bacteriocin (LCaB) of Lactobacillus curvatus CWBI-B28 enriched with or without organic acids or salts to control Listeria monocytogenes introduced artificially on sliced smoked salmon and stored at 4°C for six weeks. Inoculated slices were immersed in a solution of LCaB (8533, 33 UA/g) or in acetic or lactic acid (1, 3, 5 g/100 ml), sodium acetate or diacetate (3, 5 g/100 ml), and potassium benzo­ate or sorbate (3 g/100 ml) for five minutes and stored at 4°C in vacuum pack­ages. Additional slices containing Listeria (10 2 cfu/g) were immersed for five minutes in LCaB solutions enriched with organic acids or salts before storage at 4°C in vacuum packages. The LCaB solution without acid or salt added reduced L. monocytogenes by 1.0 log cfu/g after two weeks. Thereafter, the pathogen multiplied in samples, with growth being faster beyond the third week. LCaB in combination with 3 or 5 g/100 ml acetic acid or sodium diacetate or 3 g/100 ml benzoate. Applied individually, it did not permit growth before five weeks. In untreated (control) smoked salmon, L. monocytogenes increased to achieve 4 log cfu/g at the end of experience.

Viability of Listeria monocytogenes was monitored during refrigerated (4°C) and/or frozen (i.e., deep chilling at -2.2°C) storage on casing-cooked hams that were commercially prepared with and without potassium lactate and sodium diacetate (1.6%), buffered vinegar (2.2%), buffered vinegar and potassium lactate (1.7%), or a blend of potassium lactate, potassium acetate, and sodium diacetate (1.7%). A portion of these hams were subsequently surface treated with lauric arginate ester (LAE; 44 ppm). In phase I, hams (ca. 3.5 kg each) were sliced (ca. 0.7 cm thick, ca. 100 g), inoculated (ca. 4.0 log CFU per slice), surface treated with LAE, and stored at either 4°C for 120 days or at -2.2°C for 90 days and then at 4°C for an additional 120 days. In phase I, without antimicrobials, the population of L. monocytogenes increased by ca. 5.9 log CFU per slice within 120 days at 4°C; however, pathogen levels increased only slightly (ca. 0.45 log CFU per slice) for hams formulated with potassium lactate and sodium diacetate and decreased by ca. 1.2 log CFU per slice when formulated with the other antimicrobials. For slices held at -2.2°C and then stored at 4°C, but not treated with LAE, L. monocytogenes increased by ca. 4.5 log CFU per slice for controls, whereas when formulated with antimicrobials, pathogen levels decreased by ca. 1.4 to 1.8 log CFU per slice. For product treated with LAE, L. monocytogenes increased by ca. 4.0 log CFU per slice for controls, whereas when formulated with antimicrobials, pathogen levels decreased by ca. 0.9 to 1.9 log CFU per slice. In phase II, whole hams (ca. 1.0 kg each) containing antimicrobials were inoculated (6.8 log CFU per ham) and then stored at -2.2°C for 6 months. Pathogen levels decreased by ca. 2.0 to 3.5 log CFU per ham (without LAE treatment) and by ca. 4.2 to 5.2 log CFU per ham (with application of LAE via Sprayed Lethality in Container) when product was held at -2.2°C. In general, deep chilling hams was listericidal, and inclusion of antimicrobials in the formulation suppressed outgrowth of L. monocytogenes during extended cold storage.

Summary Low- (5%) and high-fat (20%) chicken and turkey hotdogs were formulated in three groups: no antimicrobials (control), chemical preservatives (potassium lactate and sodium diacetate) alone and partial replacement of chemical preservatives by green tea (GTE) and grape seed extracts (GSE), surface inoculated (c. 103 CFU g−1) with Listeria monocytogenes, treated with or without heat treatment (65 °C for 104 s) to determine the growth of L. monocytogenes until spoilage (28 days). Maximum growth inhibitions (c. 2.0 CFU g−1) were observed in the treatments having chemical preservatives and plant extracts regardless of the meat and fat type. Furthermore, plant extracts along with chemical preservatives demonstrated additional inhibitory effect on the growth of L. monocytogenes survivors in chicken hotdog samples followed by postpackaging heat treatment. Results demonstrated that natural GTE and GSE can partially replace the chemical preservatives and further enhance the antilisterial activities when combined with heat treatment.

Effect of potassium lactate (PL) and sodium diacetate (SD) combinations at varying levels were evaluated in low (5%) and high (20%) fat chicken and turkey hotdog model systems. All the samples were surface inoculated with Lis- teria monocytogenes (approximately 4.6 log cfu/g), vacuum packed and stored at 4 o C for 28 days to determine the effec- tive combination of PL and SD and the effect of fat content on the growth inhibition of L. monocytogenes. In chicken hot- dog samples, maximum growth inhibitions (3.4 log cfu/g) were observed in low fat samples formulated with 3.0% PL and 0.15% SD. In turkey hotdog samples, maximum growth inhibitions (3.3 log cfu/g) were observed in low fat samples for- mulated with 3.0% PL and 0.2% SD. Effective combination levels determined in low and high fat chicken were 3.0% PL and 0.15% SD, whereas in low and high fat turkey, the effective levels were 3.0% PL and 0.20% SD. Overall, fat content had significant effect (P < 0.05) on growth inhibition as indicated by higher inhibitions in low fat chicken and turkey hot- dogs than high fat samples. These results demonstrate that commercial usage levels of PL (2.0%) and SD (0.15%) alone are not sufficient to control L. monocytogenes in case of pathogen contamination.

The combined effects of high hydrostatic pressure (HHP) and a commercial liquid antimicrobial edible coating consisting of lactic and acetic acid, sodium diacetate, pectin and water (“articoat-DLP”) followed by modified atmosphere packaging (MAP) on the shelf-life of chicken breast fillets were evaluated. All samples were held at 4 °C under MAP (30% CO2/70% N2) conditions and these were assigned to the following treatments: (i), control untreated fillets (C-MAP); (ii), fillets dipped in articoat-DLP (A-MAP); (iii) HHP (300 MPa) treated fillets followed by MAP (HP-MAP) and (iv) HHP (300 MPa) treated fillets after dipping in articoat-DLP (A-HP-MAP). During storage, packages were tested at intervals for CO2 and O2 concentrations, colour (CIE L* a* b*), pH, oxidative stability (TBARS), cooking loss, Warner–Bratzler shear force measurement and sensory analysis (colour, tenderness, juiciness, chicken aroma, oxidised flavour, off-flavours and overall acceptability). Total viable counts and numbers of Pseudomonas, lactic acid bacteria (LAB), Brochothrix thermosphacta, coliforms and Escherichia coli were also determined. The A-HP-MAP combination was the most efficient in extending the durability of chicken breast fillets, which maintained their sensory and microbiological quality for up to 28 days. At the time of rejection, total counts were 6.3 ± 0.7 log cfu/g, with LAB being dominant (100%). For A-MAP and HP-MAP fillets, the storage life was estimated to be two weeks while that of the untreated fillets (C-MAP) was estimated to be one week. Colour, tenderness and overall acceptability were the best maintained sensory attributes during storage for A-HP-MAP samples. The synergistic effect of this high-pressure-based hurdle strategy was higher than those previously reported when applying several combined hurdles to poultry meat.

The effect of two antimicrobials in the enhancement solution was investigated in this study. Sensory and shelf-life characteristics were measured for beef top rounds enhanced to 110% with 0.5% sodium chloride and 0.4% sodium tripolyphosphate (CNT); CNT with a 1% solution of 80% sodium citrate plus 20% sodium diacetate (SC + D); or CNT with 2% buffered vinegar (VIN) in the final product. SC + D and VIN had less (P 0.05). However, SC + D had lower (P 0.05) for all enhancement solutions within each day. After 7 days of retail display, SC + D retarded (P < 0.05) lipid oxidation to a greater extent than VIN or CNT samples. Sodium citrate plus sodium diacetate or buffered vinegar may be included in enhancement solutions without having a large influence on subjective color, and may aid in improving sensory tenderness.

The presence and growth of Listeria monocytogenes on ready-to-eat (RTE) turkey is an important food safety issue. The antilisterial efficacy of four polysaccharide-based edible coatings (starch, chitosan, alginate and pectin) incorporating sodium lactate (SL) and sodium diacetate (SD) as well as commercial preparations Opti.Form PD4, NovaGARD™ CB1, Protect-M and Guardian™ NR100 were compared against L. monocytogenes on roasted turkey. Pectin coating treatments incorporating SL/SD, Opti.Form PD4 with or without Protect-M, and NovaGARD™ CB1 displayed higher antimicrobial efficacy against. L. monocytogenes than the other antimicrobials and coating materials. In the second phase of the study, it was investigated whether frozen storage could enhance the antilisterial effectiveness of pectin coating treatments on chilled roasted turkey. Inoculated roasted turkey samples coated with pectin-based treatments were frozen for up to 4 weeks and subsequently stored at 4 °C for 8 weeks. Frozen storage significantly enhanced the antilisterial activity of various coating treatments; with selected treatments reducing the L. monocytogenes populations by as much as 1.1 log CFU/cm 2 during the subsequent 8-week chilled storage. This study demonstrates that pectin-based antimicrobial edible coatings hold promise in enhancing the safety of RTE poultry products and frozen storage has the potential to enhance their effectiveness.

Aims: Listeria monocytogenes is a major safety concern for ready-to-eat foods. The overall objective of this study was to investigate whether prior frozen storage could enhance the efficacy of edible coatings against L. monocytogenes on cold-smoked salmon during subsequent refrigerated storage. Methods and Results: A formulation consisting of sodium lactate (SL, 1·2–2·4%) and sodium diacetate (SD, 0·125–0·25%) or 2·5% Opti.Form (a commercial formulation of SL and SD) was incorporated into each of five edible coatings: alginate, κ-carrageenan, pectin, gelatin and starch. The coatings were applied onto the surface of cold-smoked salmon slices inoculated with L. monocytogenes at a level of 500 CFU cm−2. In the first phase, the slices were first frozen at −18°C for 6 days and stored at 22°C for 6 days. Alginate, gelatin and starch appeared to be the most effective carriers. In the second phase, cold-smoked salmon slices were inoculated with L. monocytogenes, coated with alginate, gelatin or starch with or without the antimicrobials and stored frozen at −18°C for 12 months. Every 2 months, samples were removed from the freezer and kept at 4°C for 30 days. Prior frozen storage at −18°C substantially enhanced the antilisterial efficacy of the edible coatings with or without antimicrobials during the subsequent refrigerated storage. Conclusions: Plain coatings with ≥2 months frozen storage and antimicrobial edible coatings represent an effective intervention to inhibit the growth of L. monocytogenes on cold-smoked salmon. Significance and Impact of the Study: This study demonstrates the effectiveness of the conjunct application of frozen storage and edible coatings to control the growth of L. monocytogenes to enhance the microbiological safety of cold-smoked salmon.

The effects and interactions of temperature (56.3-60 °C), sodium lactate (SL; 0-4.8%), sodium diacetate (SDA; 0-2.5%), and pediocin (0-10,000 AU) on starved Listeria monocytogenes (10(7) CFU/g) on bologna were investigated. Bologna slices containing SL and SDA in the formulation were dipped in pediocin, surface inoculated, and treated at various temperatures using combinations of parameters determined by central composite design. D-values were calculated. The observed D-values ranged from 2.8 min at 60 °C to 24.61 min at 56.3 °C. Injury ranged from 9.1 to 76% under various conditions. The observed D-values were analyzed using second order response surface regression for temperature, SL, SDA, and pediocin, and a predictive model was developed. Predicted D-values were calculated and ranged from 3.7 to 19 min for various combinations of parameters. Temperature alone reduced the predicted D-values from 33.96 min at 56.3 °C to 11.51 min at 60 °C. Addition of SL showed a protective effect. Other combination treatments either reduced or increased D-values depending on temperature. The combination of SL and SDA was effective at lower temperatures, however, higher levels of SDA at higher temperatures made the organism more heat resistant. Pediocin (up to 5000 AU) with increasing temperature and SDA reduced D-values. Depending on temperature and concentration, the interactions between various additives can affect thermal inactivation of L. monocytogenes on bologna. Starvation rendered L. monocytogenes more susceptible to heat and additives.

The relatively high prevalence of Listeria monocytogenes in ready-to-eat (RTE) turkey products is of great concern. The overall objective of this study was to develop antimicrobial edible coating formulations to effectively control the growth of this pathogen. The antimicrobials studied were nisin (500IU/g), Novagard CB 1 (0.25%), Guardian NR100 (500ppm), sodium lactate (SL, 2.4%), sodium diacetate (SD, 0.25%), and potassium sorbate (PS, 0.3%). These were incorporated alone or in binary combinations into five edible coatings: alginate, kappa-carrageenan, pectin, xanthan gum, and starch. The coatings were applied onto the surface of home-style poached and processed deli turkey discs inoculated with ~3log CFU/g of L. monocytogenes. The turkey samples were then stored at 22 degrees C for 7days. For poached and processed deli turkey, the coatings were found to be equally effective, with pectin being slightly less effective than the others. The most effective poached turkey treatments seemed to be SL (2.4%)/SD (0.25%) and Nisin (500IU/g)/SL (2.4%), which yielded final populations of 3.0 and 4.9log CFU/g respectively compared to the control which was 7.9log CFU/g. For processed deli turkey, the most effective antimicrobial treatments seemed to be Nisin (500IU/g)/SD (0.25%) and Nisin (500IU/g)/SL (2.4%) with final populations of 1.5 and 1.7log CFU/g respectively compared to the control which was 6.5log CFU/g. In the second phase of the study, home-style poached and store-purchased roasted (deli) turkey inoculated with the pathogen at a level of ~3log CFU/g were coated with alginate incorporating selected antimicrobial combinations and stored for 8weeks at 4 degrees C. Alginate coatings supplemented with SL (2.4%)/PS (0.3%) delayed the growth of L. monocytogenes with final counts reaching 4.3log CFU/g (home-style poached turkey) and 6.5log CFU/g (roasted deli turkey) respectively while the counts in their untreated counterparts were significantly higher (P

Combinations of organic acids, sodium lactate (SL; Fisher Scientific Co. LLC., Pittsburgh, PA), potassium lactate (PL; City Chemical LLC., West Haven, CT) and sodium diacetate (SD; Spectrum Chemical MFG. Corp., Gardena, CA), were applied in the raw product and as a post-cook dip to determine their inhibitory effect on Listeria monocytogenes in ham deli loaves. Loaves were formulated with an organic acid as an ingredient, cooked, cooled, inoculated with streptomycin-resistant L. monocytogenes and then dipped in an organic acid treatment. Treatments consisted of PL in the raw product and PL in the dip, PL with SL/PL/SD dip, SL/SD with PL dip, and SL/SD with SL/PL/SD dip. Loaves were examined on a weekly basis for 56 days. Treatments containing PL with SL/PL/SD, SL/SD with PL, and SL/SD with SL/PL/SD had similar inhibition effects on L. monocytogenes from day 0 to day 42 (P

Potassium diformate (KDF) has been regarded as an alternative to antibiotic growth promoters for animals. This paper delineates a 100% atom economical process for the preparation of KDF from formic acid and potassium formate. Parametric optimization of the synthesis was conducted with respect to reaction time, reaction temperature, and molar ratio of the reactants by employing orthogonal design of experiment method. The results manifested a molar ratio of HCOOH to HCOOK of 1.3, reaction temperature of 65 °C, and reaction time of 30 min as the optimal conditions with a KDF product yield of 94.0%. Efforts were also made to explore the antimold performance of KDF on animal feed using the plate count method. Compared with sodium diacetate (SDA), the widely used mold inhibitor, KDF exhibited even better antimold performance for animal feed. To our knowledge, this work first proved the applicability of KDF as a mold inhibitor for animal feed.

This study investigated the antimicrobial effects of garlic, potassium lactate and sodium diacetate (PL/SDA) mixture, ɛ-polylysine, and potassium sorbate (PS) alone or in combinations of them on the growth of foodborne pathogens and production of staphylococcal enterotoxin A (SEA) in ready-to-eat (RTE) pyeonyuk at various temperatures. Lag times (LTs) of Salmonella Typhimurium were longer than those of Staphyloccus aureus at all tested temperatures, regardless of antimicrobial agent. The growth of S. Typhimurium and S. aureus were not observed in pyeonyuk made with 3% PL/SDA mixture or 1.5% ɛ-polylysine at 10°C. The 0.2% of PS, which is the permitted level for meat products, did not inhibit the growth of S. Typhimurium and S. aureus. Although growth of S. aureus in RTE pyeonyuk with 3% PL/SDA mixture and 1.5% ɛ-polylysine was observed, SEA was not produced at 17, 24, and 30°C, suggesting the application of PL/SDA mixture or ɛ-polylysine to reduce the risk related to the consumption of pyeonyuk.

Microwave oven heating was evaluated for inactivation of Listeria monocytogenes on inoculated and stored frankfurters. Frankfurters formulated without/with 1.5% potassium lactate and 0.1% sodium diacetate were inoculated with L. monocytogenes (1.9 +/- 0.2 log CFU/cm(2)), vacuum-packaged, and stored (4 degrees C) to simulate conditions prior to purchase by consumers. At storage days 18, 36, and 54, packages were opened and placed at 7 degrees C, simulating aerobic storage in a household refrigerator. At 0, 3, and 7 d of aerobic storage, 2 frankfurters were placed in a bowl with water (250 mL) and treated in a household microwave oven at high (1100 W) power for 30, 45, 60, or 75 s, or medium (550 W) power for 60 or 75 s. Frankfurters and the heating water were analyzed for total microbial counts and L. monocytogenes populations. Exposure to high power for 75 s reduced pathogen levels (0.7 +/- 0.0 to 1.0 +/- 0.1 log CFU/cm(2)) to below the detection limit (-0.4 log CFU/cm(2)) on frankfurters with lactate/diacetate, even after 54 d of vacuum-packaged storage followed by 7 d of aerobic storage. For frankfurters without lactate/diacetate, high power for 75 s caused reductions between1.5 and 5.9 log CFU/cm(2) from control levels of 1.5 +/- 0.1 to 7.2 +/- 0.5 log CFU/cm(2). Depending on treatment and storage time, the water used to reheat the frankfurters had viable L. monocytogenes counts of-2.4 to 5.5 +/- 0.5 log CFU/mL. The results indicated that frankfurters should be reheated in a microwave oven at high power for 75 s to inactivate up to 3.7 log CFU/cm(2) of L. monocytogenes contamination.

The antilisterial activity of sodium diacetate and pediocin (ALTA 2341) on frankfurters was evaluated in combination with hydrodynamic pressure processing (HDP). Minimum inhibitory concentration (MIC) of these strains as determined in tryptic soy broth was 0.4% and >600 AU/mL, for sodium diacetate and ALTA 2341, respectively. Frankfurters were surface inoculated with a five-strain mixture of Listeria monocytogenes after dipping in (1) control (sterile water); (2) 5% sodium diacetate; (3) 3% ALTA 2341(P1); (4) 6% ALTA 2341 (P2); (5) P1 + sodium diacetate; and (6) P2 + sodium diacetate for 5 min. The frankfurters were vacuum-packaged and treated with hydrodynamic pressure or without HDP. Frankfurters were analyzed at 0, 7, 14 and 28 d for pH, L. monocytogenes (MOX) and aerobic (TSAYE) cell populations during storage at 4C. Antimicrobials and HDP treatment did not change (P

The objective of this study was to determine the effect of antimicrobials on the survival and proliferation of Listeria monocytogenes in turkey breast rolls following electron-beam irradiation. Six antimicrobial additive treatments that include no preservatives (control), 0.1% potassium benzoate (PB), 2% sodium lactate (SL), 0.1% potassium benzoate plus 2% sodium lactate (PB + SL), 2% sodium lactate plus 0.1% sodium diacetate (SL + SDA), and 0.1% potassium benzoate, 2% sodium lactate, and 0.1% sodium diacetate (PB + SL + SDA) were used. Sliced turkey breast rolls were artificially inoculated with approximately 10(6) cfu/cm(2) of 5-strain L. monocytogenes cocktails, then vacuum-packaged and irradiated at 0, 1.0, 1.5, 2.0, or 2.5 kGy. The radiation dose (kGy) that results in 90% reduction of viable cells for breast rolls, D(10) value, with various additive treatments ranged from 0.56 to 0.58 kGy. Adding PB (0.1%) or SL (2%) in turkey rolls failed to prevent L. monocytogenes from growing during refrigerated storage. In turkey rolls added with 2 (PB + SL or SL + SDA) or 3 (PB + SL + SDA) antimicrobial combinations had 2 or 3 wk of lag phases before L. monocytogenes growth, respectively. Irradiating turkey rolls, which were added with PB + SL or SL + SDA, at 1.0 kGy was effective in suppressing the growth of L. monocytogenes for about 6 wk when stored at 4 degrees C. No growth of L. monocytogenes after irradiation occurred during 42 d of storage for 2.0 kGy irradiated breast rolls formulated with 0.1% PB + 2% SL, 2% SL + 0.1% SDA or 0.1% PB + 2% SL + 0.1% SDA, and 1.0 kGy irradiated turkey breast with 0.1% PB + 2% SL + 0.1% SDA. Sensory panelists found that low-dose irradiation (1.0 kGy) had no effect on the sensory characteristics of ready-to-eat turkey breast rolls. Including SL + SDA had slightly negative effect for nonirradiated turkey breast rolls, but the sensory characteristics of 1.0 kGy irradiated turkey roll containing SL + SDA was not significantly different from the others receiving 1.0 kGy irradiation. For microbial safety, PB + SL and SL + SDA antimicrobial treatments combined with 1.0 kGy or 2.0 kGy irradiation are a promising technology.

Hops beta acids (HBA) are parts of hops flowers used to preserve wort and provide flavor in beer, and are reported as having antimicrobial properties. This study evaluated the antilisterial activity of HBA alone or in combination with other known antimicrobials in a culture broth medium. Listeria monocytogenes (10-strain mixture) was inoculated (2.6 to 2.8 log CFU/mL) into tryptic soy broth supplemented with 0.6% yeast extract (TSBYE) without (control) or with HBA (0.5 to 5.0 microg/mL), potassium lactate (1.0%), sodium diacetate (0.25%), or acetic acid (0.1%), alone or in combination with HBA (0.5 to 3.0 microg/mL). Survival/growth of the pathogen during storage at 4 degrees C (35 d), 10 degrees C (20 d), or 25 degrees C (2 d) was periodically monitored by spiral plating onto tryptic soy agar plus 0.6% yeast extract. As expected, TSBYE without antimicrobials (control) supported rapid pathogen growth with growth rates of 0.40, 2.88, and 9.58 log CFU/mL/d at 4, 10, and 25 degrees C, respectively; corresponding Y(end) values exceeded 9.0 log CFU/mL at 35, 20, and 2 d storage. HBA used alone (1.0 to 5.0 microg/mL) inhibited growth of L. monocytogenes at all 3 temperatures, with inhibition being more pronounced at higher concentrations and at the lower storage temperature (4 degrees C). The antilisterial activity of HBA (0.5 to 3.0 microg/mL) was enhanced when combined with sodium diacetate, acetic acid, or potassium lactate, achieving complete inhibition at 4 degrees C when 3.0 microg/mL HBA were used in combination with each of the above antimicrobials. Overall, HBA exhibited promising antilisterial activity in a broth medium and further studies are needed to investigate its potential antilisterial effects in food products.

Listeriosis concerns have led to increased antimicrobial use; reformulation may affect quality. The objective was to determine the effects of potential antimicrobials on quality of natural casing frankfurters. Eleven treatments were used: no antimicrobials (control); 3.0% sodium lactate and sodium diacetate blend (SL+SD); 1.0%, 2.5%, and 3.5% buffered sodium citrate (SC); 1.0%, 2.5%, and 3.5% buffered sodium citrate and sodium diacetate blend (SC+SD); and 1.0%, 2.5%, and 5.0% whey protein peptides (WP). Trained and consumer panelists analyzed sensory characteristics. Cooking yield was unaffected by treatment (P0.05). Addition of SC and SC+SD decreased pH (P0.05). Texture profile analysis was conducted. Hunter color values and growth of aerobic bacteria and lactic acid bacteria were monitored over 15 weeks of storage. No samples reached spoilage. SL+SD 3% caused few changes; WP caused changes perceived as negative; and SC and SC+SD caused changes often perceived as positive.

Ethylene copolymer film was coated with chitosan by attachment of the polymer to the corona-treated surface of the film, and the composite film was analysed for antimicrobial activity. The film was active against bacteria in 0.625 mM phosphate buffer; it reduced colony counts of Escherichia coli 25922 and of Listeria monocytogenes Scott A by 5 and 2–3 log10, respectively after 24 h exposure. The activity of the chitosan-coated film against bacteria in buffer was increased when silver ions were incorporated into the films as demonstrated by complete killing of Escherichia coli O157:H7 DD3795 and the chicken exudate isolate Stenotrophomonas maltophilia within 2 h in buffer. The film was active against L. monocytogenes Scott A in 0.5% buffered peptone water up to a pH of about 7.0. Tests on beef and chicken meat exudates revealed antimicrobial activity of the film against Escherichia coli O157:H7 and L. monocytogenes Scott A of about 2 and 1–2 log10 reductions in colony-forming units, respectively. The antimicrobial activity of the film against L. monocytogenes Scott A was also tested on turkey breast, and a log10 reduction of about 1.7 log10 units after 10 days and 1.2 log10 after 15 days at 4°C was achieved. Exposure to chitosan-coated film and 350 MPa of pressure, 55°C or 1% sodium diacetate resulted in a synergistic effect. Copyright © 2008 John Wiley & Sons, Ltd

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 degrees 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 degrees C and 4 to 13 days at 8 degrees C. The growth was inhibited at 4 and 8 degrees 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 degrees 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.

This study investigated the use of sodium levulinate to prevent outgrowth of Listeria monocytogenes in refrigerated ready-to-eat (RTE) meat products. Turkey breast roll and bologna were formulated to contain 1%, 2%, or 3% (w/w) sodium levulinate, 2% sodium lactate, a 2% combination of sodium lactate and sodium diacetate (1.875% sodium lactate and 0.125% sodium diacetate), or no antimicrobial (control). Samples of the RTE products were sliced, inoculated with 10(2) to 10(3) CFU/cm(2) of a 5-strain cocktail of L. monocytogenes, vacuum packaged, and stored at refrigeration temperature for 0 to 12 wk. Counts reached 10(8) CFU/cm(2) on control turkey roll product after 8 wk, and over 10(7) CFU/cm(2) on control bologna after 12 wk. Addition of 2% or more sodium levulinate to turkey roll and 1% or more sodium levulinate to bologna completely prevented growth of L. monocytogenes during 12 wk of refrigerated storage. A consumer taste panel with pathogen-free samples found no differences in the overall liking among the preparations of turkey roll or among preparations of bologna. These results show that sodium levulinate is at least as effective at inhibiting outgrowth of L. monocytogenes in RTE meat products as the current industry standards of lactate or lactate and diacetate, and levulinate addition does not alter the overall liking of the RTE meat products.

This study compared the performance of four primary mathematical models to study the growth kinetics of Listeria monocytogenes ribotypes grown at low temperature so as to identify the best predictive model. The parameters of the best-fitting model were used to select the fastest growing strains with the shortest lag time and greatest growth rate. Nineteen food, human and animal L. monocytogenes isolates with distinct ribotype were grown at 4, 8, and 12 degrees C in tryptic soy broth and slurries prepared from cooked uncured sliced turkey breasts (with or without potassium lactate and sodium diacetate, PL/SD) and cooked cured frankfurters (with or without PL/SD). Separate regressions were performed on semi-logarithm growth curves to fit linear (based on Monod) and non-linear (Gompertz, Baranyi-Roberts, and Logistic) equations and performance of each model was evaluated using an F-test. No significant differences were found in the performance of linear and non-linear models, but the Baranyi model had the best fit for most growth curves. The maximum growth rate (MGR) of Listeria strains increased with the temperature. Similarly MGR was found significantly greater when no antimicrobials were present in the formulation of turkey or frankfurter products. The variability in lag times and MGRs in all media as determined by the Baranyi model was not consistent among strains. No single strain consistently had the fastest growth (shortest lag time, fastest MGR, or shortest time to increase 100-fold), but nine strains were identified as fastest growing strains under most growth conditions. The lack of association between serotype and fastest strain was also observed in the slurry media study. The fastest growing strains resulting from this study can be recommended for future use in L. monocytogenes challenge studies in delicatessen meat and poultry food matrices, so as to develop conservative pathogen growth predictions.

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 degrees 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 degrees 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.

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 (10(1) or 10(3) CFU g(-1)) and storage temperature (4 or 8 degrees 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 degrees C) and even under abusive temperature conditions (i.e., 8 degrees C). During the challenge studies and in the absence of either organic acid salt, L. monocytogenes numbers increased by 1000-fold after 20 days at 8 degrees C and 10-fold after 42 days at 4 degrees 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.

Refrigerated ready-to-eat (RTE) meats contaminated with Listeria monocytogenes were implicated in several listeriosis outbreaks. Lactate and diacetate have been shown to control L. monocytogenes in RTE meats. The objective of this study was to examine and model the effect of lactate (1.0% to 4.2%) and diacetate (0.05% to 0.2%) in ground ham on the lag phase duration (LPD, h) and growth rate (GR, log CFU/h) of L. monocytogenes at a range of temperatures (0 to 45 degrees C). A 6-strain mixture of L. monocytogenes was inoculated into ground ham containing lactate and diacetate, and stored at various temperatures. The LPD and GR of L. monocytogenes in ham as affected by lactate, diacetate, and storage temperature were analyzed and accurately represented with mathematical equations. Resulting LPD and GR equations for storage temperatures within the range of 0 to 36 degrees C significantly represented the experimental data with a regression coefficient of 0.97 and 0.96, respectively. Significant factors (P < 0.05) that affected the LPD were temperature, lactate, diacetate, and the interactions of all three, whereas only temperature and the interactions between temperature and lactate and diacetate had a significant effect on GR. At suboptimal growth temperatures (< or = 12 degrees C) the increase of lactate and diacetate concentrations, individually or in combination, extended the LPD. The effect of higher concentrations of both additives on reducing the GR was observed only at temperatures that were more suitable for growth of L. monocytogenes, that is, 15 to 35 degrees C. These data may be used to assist in determining concentrations of lactate and diacetate in cooked ham products to control the growth of L. monocytogenes over a wide range of temperatures during manufacturing, distribution, and storage.

The most commonly used poultry marinades include salt and sodium tripolyphosphate, which have been shown to increase meat yield and water-holding capacity, as well as improve color and texture. Recently, several poultry further-processing facilities have begun using more acidic (pH ˜4) type marinades such as sodium lactate, sodium citrate, and sodium diacetate (alone or in combination) to combat the growth of Listeria monocytogenes in further-processed meat loaves. Because the acidic marinades currently used in turkey further-processing have a low pH (˜4) compared with the previously used salt and sodium tripolyphosphate (˜pH 9), these marinades may cause meat quality problems. This review paper will discuss aspects of poultry food safety and meat quality and how acidic marinades can be used to improve safety, specifically by controlling L. monocytogenes growth, and how they affect quality of the meat products. Current industry practices will be discussed and reviewed.

The fate of acid-adapted and nonadapted Listeria monocytogenes inoculated onto bologna slices (formulated with or without antimicrobials) was examined during storage and after exposure to in vitro gastric challenge. Bologna slices formulated with no antimicrobials (control), 3% sodium lactate (SL), or 1.8% SL plus 0.25% sodium diacetate (SD) were inoculated (2 log CFU/cm2) with a 10-strain composite of acid-adapted or nonadapted L. monocytogenes strains. Growth or survival of the two inocula on bologna was evaluated during vacuum-packaged storage (10 degrees C) for up to 36 days. Survival of previously acid-adapted or nonadapted L. monocytogenes on stored bologna exposed to simulated gastric fluid (adjusted to pH 1.0 with HCl) for 20, 40, and 60 min also was determined. As expected, inclusion of antimicrobials in the product formulation inhibited growth of L. monocytogenes during storage of vacuum-packaged bologna compared with growth on control samples. Acid adaptation of L. monocytogenes prior to product inoculation did not affect subsequent survival or growth on bologna or resistance to simulated gastric fluid (P0.05). Survival of L. monocytogenes exposed to simulated gastric fluid during storage increased with product age, growth phase of the cells, and possibly age of the cells, particularly for control samples (no antimicrobials), in which the pathogen grew uninhibited to approximately 6 log CFU/cm2 by day 8 of storage. Inhibition of L. monocytogenes growth on product formulated with antimicrobials was associated with only sporadic and small numbers of survivors following exposure of these samples to simulated gastric fluid, especially in samples stored longer. However, cell numbers in these treatment groups before the gastric challenge did not exceed 3.8 log CFU/cm2. Inhibition of growth on product with antimicrobials precluded detection of survivors resistant to the effects of simulated gastric fluid.

The safety of ready-to-eat meat products such as frankfurters can be enhanced by antimicrobials and postpackaging treatment to control the growth of Listeria monocytogenes. We evaluated the effectiveness of dipping frankfurters in sodium lactate (SL), sodium diacetate (SD) and nisin (N) solutions, followed by hydrodynamic pressure processing (HDP), to control L. monocytogenes during storage at 4C for 28 days. Frankfurters were surface inoculated with a five-strain mixture of L. monocytogenes after dipping in (1) control (sterile water), (2) 10% SL, (3) 5% SD, (4) SL + SD, (5) N (5000 IU/mL), (6) N + SL, (7) N + SD and (8) N + SL + SD for 5 min. The frankfurters were vacuum packed and were either treated with or without hydrodynamic pressure. The frankfurters were periodically analyzed for populations of L. monocytogenes on modified Oxford agar, aerobic cell populations on tryptic soy agar with 0.6% yeast extract and pH on days 0, 7, 14 and 28. HDP treatment significantly reduced L. monocytogenes populations in frankfurters. Dipping treatments containing N showed greater L. monocytogenes reduction than that with SL and/or SD treatment; however, the difference was not significant. The combination of N and HDP treatment resulted in more than 2 log cfu/g reduction in L. monocytogenes populations after 28-days storage. A synergistic effect between N and HDP was observed for inhibition of L. monocytogenes. The reduction in aerobic cell populations during storage of antimicrobials and HDP-treated frankfurters was similar to that of L. monocytogenes. These results indicate that using N as a dipping treatment followed by HDP treatment is more effective for inhibition of the pathogen during storage at 4C. PRACTICAL APPLICATIONS Hydrodynamic pressure processing, an innovative post-harvest technology for meat tenderization, uses a high-energy explosive to generate a supersonic shock wave in a liquid medium. HDP treatment, primarily studied for tenderness improvement in muscle food products, has been effective in reducing bacterial populations in meats. Nisin has greater antilisterial activity than sodium lactate or sodium diacetate. Dipping frankfurters in nisin followed by the hydrodynamic pressure treatment could be used to reduce 2 log L. monocytogenes populations in frankfurters during storage at 4C.

This study reports the gene expression and filamentation in Listeria monocytogenes 08-5923 following exposure to food preservatives sodium lactate (NaL) and sodium diacetate (SD). L. monocytogenes 08-5923 was challenged with a mixture of NaL/SD, NaL or sodium acetate at 37 °C in tryptic soy broth. In the initial study, L. monocytogenes 08-5923 was exposed to NaL/SD for 24 h. The transcriptome was investigated by RNA sequencing. A stress response network was discovered in L. monocytogenes 08-5923, which is mediated by genes encoding two-component systems (hisJ, lisK, OmpR family gene, resE) and RNA polymerase factors (sigC, sigH). NaL/SD resulted in the down-regulation of genes in glycolysis (pykA, eno, fbaA, pgm) and up-regulation of genes in DNA repair (radC), cell division (ftsE) and cell structure synthesis (flagella synthesis: flgK, fliF, fliD). Filamentation was monitored by flow cytometry. NaL/SD mixture resulted in filamentation in L. monocytogenes 08-5923. Longer exposure was required to induce filamentation in L. monocytogenes for SD (24 h) than for NaL (8 h) when cells were exposed to individual salt. The quantitative real time PCR analysis revealed the down-regulation of ftsE in filamented cells of Listeria exposed to NaL or sodium acetate.

Inhibition effects of several combinations of sodium lactate (SL), sodium acetate, sodium diacetate (SDA) on the growth of Listeria monocytogenes and Salmonella enterica serotype Enteritidis were investigated in minced beef. The samples inoculated with 4.60 log cfu/g of Salmonella enteritidis and 4.70 log cfu/g of L. monocytogenes were treated with sodium salts and their combinations and stored at 4C. Sodium salts decreased the growth rate of S. enterica serotype Enteritidis. Combinations of the salts were bactericidal to S. enterica serotype Enteritidis but the growth of L. monocytogenes was delayed only by using the combination of 2.5% SL and 0.2% SDA.