Effectiveness of potassium lactate and sodium diacetate in combination with irradiation to control Listeria monocytogenes on frankfurters

ABSTRACT:  The use of antimicrobial ingredients in combination with irradiation is an effective antilisterial intervention strategy for ready-to-eat meat products. Microbial safety was evaluated for frankfurters formulated with 0% or 3% added potassium lactate/sodium diacetate solution and inoculated with Listeria monocytogenes before or after treatment with irradiation (0, 1.8, or 2.6 kGy). Frankfurters were stored aerobically or vacuum packaged and L. mo nocytogenes counts and APCs were determined while refrigerated. The incorporation of lactate/diacetate with or without irradiation had a strong listeriostatic effect for aerobically stored frankfurters. Outgrowth was suppressed and counts were not different from initial counts (5.2 log CFU/frank compared with 5.0 log CFU/frank); however, those without the additive increased steadily (5.4 to 9.3 log CFU/frank). Irradiation treatments alone had higher L. monocytogenes counts after 3 wk. For vacuum-packaged frankfurters, both the addition of lactate/diacetate and irradiation were effective at controlling growth after 8 wk. Large and incremental reductions in total counts were seen for irradiation treatments. Initial counts were reduced by 3 log CFU with the application of 1.8 kGy while 2.6 kGy decreased counts over 5 log CFU. These reductions were maintained throughout storage for lactate/diacetate-treated frankfurters. By 8 wk, L. monocytogenes counts on 1.8 and 2.6 kGy irradiated frankfurters without lactate/diacetate increased to 7.43 and 6.13 log CFU, respectively. Overall, lactate/diacetate retarded the outgrowth of L. monocytogenes on frankfurters throughout aerobic storage and the combination of irradiation and 3% lactate/diacetate reduced and retarded growth of L. monocytogenes , especially during the last 2 wk of vacuum-packaged storage.     

Inactivation of Listeria innocua on frankfurters that contain potassium lactate and sodium diacetate by flash pasteurization

ABSTRACT:  Listeria monocytogenes , a psychrotrophic foodborne pathogen, is a recurring postprocess contaminant on ready-to-eat meat (RTE) products, including frankfurters. Potassium lactate (PL) and sodium diacetate (SDA) are FDA-approved antimicrobials that inhibit the growth of L. monocytogenes when incorporated into the formulation of fine emulsion sausage. Flash (steam) pasteurization (FP) has been shown to reduce levels of L. monocytogenes , and its surrogate L. innocua , on frankfurter surfaces. The ability of FP to inactivate and prevent the growth of the L. monocytogenes surrogate L. innocua in a pilot plant setting was investigated. FP treatment (1.5 s, 121 °C) of single layers of frankfurters that were surface-inoculated with either 5, 4, or 3 log CFU/g of L. innocua immediately before FP (1.5 s, 121 °C) resulted in log reductions of 1.97 (± 0.11), 2.03 (± 0.10), or 2.07 (± 0.14), respectively. Inoculum level had no effect on the inactivation of L. innocua . Following 8 wk of refrigerated storage (4 °C), L. innocua levels decreased by 0.5 log in non-FP-treated frankfurter packs, while the 2 log reduction of L. innocua was maintained for FP-treated frankfurters. FP (1.5 s, 121 °C) had no effect on frankfurter color or texture. Because the numbers of L. monocytogenes associated with contaminations of ready-to-eat meats are typically very low, the use of FP in combination with PL and SDA has the potential to reduce the number of frankfurter recalls and foodborne illness outbreaks.     

Properties of refrigerated ground beef treated with potassium lactate and sodium diacetate

BACKGROUND: Ground meat is product that perishes easily and therefore various preservatives are applied to prolong its shelf life. The aim of this study was to investigate the effect of potassium lactate and sodium diacetate (Protec K‐DI preparation) on general proteolytic activity, protein degradation, texture, colour and water‐holding capacity of vacuum‐packaged ground beef. RESULTS: The activity of endogenous proteolytic enzymes, and hence the rate of protein hydrolysis changed significantly (P < 0.05) during refrigerated storage. The proteolysis was more intensive in the meat with the preservative than in a control sample. According to the results of SDS‐PAGE, the level of myosin in ground beef decreased with increasing storage time, whereas the preservative did not have a significant effect (P > 0.05) on these changes. However, its impact was the most significant in the case of tropomyosin and troponin T content, as well as changes of 30 kDa protein content. The preservative as well as the increase in storage time influenced an increase in content of polypeptides, peptides and some amino acids in the samples, and had an inhibiting effect on unfavourable changes in ground beef hardness. The preservative addition allowed the meat to maintain desired meat colour, and the main pigment during refrigerated storage was oxymyoglobin (MbO₂). CONCLUSION: Results showed that the Protec K‐DI preparation can be useful in minced meat production as a good stabiliser of colour and texture despite the increase observed in proteolytic activity after the preservative addition. Copyright © 2007 Society of Chemical Industry     

Control of Listeria monocytogenes in ready-to-eat meats containing sodium levulinate, sodium lactate, or a combination of sodium lactate and sodium diacetate

ABSTRACT:  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 10² to 10³ CFU/cm² of a 5-strain cocktail of L. monocytogenes , vacuum packaged, and stored at refrigeration temperature for 0 to 12 wk. Counts reached 10⁸ CFU/cm² on control turkey roll product after 8 wk, and over 10⁷ CFU/cm² 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.     

Antimicrobial activity of lactic acid bacteria against Listeria monocytogenes on frankfurters formulated with and without lactate/diacetate

Contamination by Listeria monocytogenes has been a constant public health threat for the ready-to-eat (RTE) meat industry due to the potential for high mortalities from listeriosis. Lactic acid bacteria (LAB) have shown protective action against various pathogenic bacteria. The aim of this study was to evaluate the antilisterial activity of a combination of three LAB strains (Lactiguard®) on L. monocytogenes. The combination of the LAB was inhibitory to L. monocytogenes inoculated onto frankfurters not containing lactate/diacetate after 8 weeks of refrigerated storage (0.6 log reduction compared to L. monocytogenes only control), and when a cell free extract (CFS) of the LAB was added with LAB even more inhibition was obtained (1.2 log reduction compared with L. monocytogenes only). In frankfurters containing lactate/diacetate the LAB and the LAB plus CFS were more effective in reducing growth of L. monocytogenes after 8 weeks of refrigerated storage (2 and 3.3 log reductions respectively).     

Modeling the lag phase and growth rate of Listeria monocytogenes in ground ham containing sodium lactate and sodium diacetate at various storage temperatures

ABSTRACT:  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 °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 °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 (≤12 °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 °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.     

Effects and interactions of sodium lactate, sodium diacetate, and pediocin on the thermal inactivation of starved Listeria monocytogenes on bologna

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 (10⁷ 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.     

Antimicrobial activity of lactic acid bacteria against Listeria monocytogenes on frankfurters formulated with and without lactate/diacetate

Contamination by Listeria monocytogenes has been a constant public health threat for the ready-to-eat (RTE) meat industry due to the potential for high mortalities from listeriosis. Lactic acid bacteria (LAB) have shown protective action against various pathogenic bacteria. The aim of this study was to evaluate the antilisterial activity of a combination of three LAB strains (Lactiguard®) on L. monocytogenes. The combination of the LAB was inhibitory to L. monocytogenes inoculated onto frankfurters not containing lactate/diacetate after 8 weeks of refrigerated storage (0.6 log reduction compared to L. monocytogenes only control), and when a cell free extract (CFS) of the LAB was added with LAB even more inhibition was obtained (1.2 log reduction compared with L. monocytogenes only). In frankfurters containing lactate/diacetate the LAB and the LAB plus CFS were more effective in reducing growth of L. monocytogenes after 8 weeks of refrigerated storage (2 and 3.3 log reductions respectively).     

Combined effects of potassium lactate and calcium ascorbate as sodium chloride substitutes on the physicochemical and sensory characteristics of low-sodium frankfurter sausage

The purpose of this study was to evaluate the combined effects of sodium chloride (NaCl) substitutes, including potassium lactate (K-lactate) and calcium ascorbate (Ca-ascorbate), on the physicochemical and sensory characteristics of low-sodium frankfurter sausage (1.2% content of NaCl). Sausages produced with 40% substitution of NaCl with combined K-lactate and Ca-ascorbate showed a higher value of lightness (P < 0.001) than sausages containing 2.0% content of NaCl (control). However, the sensory panels were unable to distinguish a difference in color intensity between the control and treatment groups. Frankfurter sausages produced with 30% K-lactate and 10% Ca-ascorbate exhibited similar water-holding capacity, textural properties, and organoleptic characteristics (P > 0.05) when compared to control sausages. Thus, the use of these salt mixtures is a good way to reduce the NaCl content in meat products while maintaining the quality of meat products. These results may be useful in developing low-sodium meat products.     

Sodium lactate,sodium diacetate and pediocin: Effects and interactions on the thermal inactivation of Listeria monocytogenes on bologna

The effects and interactions of temperature (56.3–60 °C), sodium lactate (SL; 0–4.8%), sodium diacetate (SD; 0–0.25%) and pediocin (0–10,000 AU) on Listeria monocytogenes on bologna were studied and a predictive inactivation model was developed. Bologna was manufactured with different SL/SD concentrations in the formulation, dipped in pediocin solution and treated at different temperatures using combinations of parameters determined by central composite design. D-values were calculated and analyzed using second order response regression. Predicted D-values were also calculated. The observed D-values for L. monocytogenes on bologna ranged from 2.10 to 35.59 min. Temperature alone decreased predicted D-values from 99.02 min at 56.3 °C to 44.71 min at 60.0 °C. Adding SL decreased D-values (85.43–22.71 min) further; however, heat and SD combined was the most effective for reducing L. monocytogenes on bologna. An SD level of 0.25% at 58.2 °C had the overall lowest predicted D-value (15.95 min). Combination treatments increased or decreased D-values, depending on the temperature. Pediocin (2500 and 5000 AU) and heat decreased D-values, but exhibited a protective effect at higher concentrations (≥7500 AU). The results showed that interactions between additives in formulations can vary at different temperatures/concentrations, thereby affecting thermal inactivation of foodborne pathogens in meat products. Hence, food processors should modify food formulations carefully, and verify with adequate testing so that product safety is not compromised.     

Beef sausage structure affected by sodium chloride and potassium lactate

A histological and ultrastructural study was conducted to characterize changes in the muscle fibre structure of three fresh sausage preparations, depending on meat composition, sodium chloride (NaCl) and potassium lactate (K-lactate) contents. After addition of 0.8% and 1.6% NaCl, 65% and 51%, respectively, of the area observed showed well preserved fibres (histological data). The altered regions presented a large disorganization of the myofilaments and a solubilization of the sarcolemma and of the Z lines. K-lactate addition had no marked effects on meat structure. The preparation containing some sheep meat was more sensitive to salt than the others containing only bovine meat. The level of alteration was much lower than those obtained in pork meat in another study. Technological conditions used to modify the internal muscle fibre structure during sausage processing depend on the species used. Therefore, the classification of the sausage preparation to “meat preparation” or “meat product” under the EU regulation (EC) No. 853/2004 (which assign meat preparations to meat if the product has undergone a process insufficient to modify the internal muscle fibre structure of the meat) must be systematically controlled when changing the meat sausage composition.     

高效液相色谱法测定食品中双乙酸钠和 丙酸盐含量

目的 建立食品中双乙酸钠、丙酸钠（钙）同时测定的高效液相色谱检测方法。方法 样品中的双乙酸钠、丙酸钠（钙）经（1 1）盐酸溶液酸化后转化为乙酸与丙酸,使用有机溶剂进行萃取后在40℃下水浴挥干,浓缩后使用流动相定容,经C18色谱柱分离,在215nm波长处测定,外标法定量。结果 在优化的实验条件下,双乙酸钠和丙酸钠（钙）在0.5～5.0mg/mL范围内线性关系良好,相关系数均大于0.9998,方法的检出限为2mg/kg,加标回收率在87.3%～100.6%范围之内,相对标准偏差在0.89%～4.53%之间。结论 该方法前处理简便快速,定量准确可靠,灵敏度高,适用于各类食品中双乙酸钠、丙酸钠（钙）含量的同时测定。     

Reducing salt intake from meat products by combined use of lactate and diacetate salts without affecting microbial stability

In the framework of the trend towards lowering the salt content in meat products, an experiment was set up to determine combined effect of reducing the salt content with 20% or 40% and adding 2% or 3% Purasal^® Opti.Form PD 4 (a mixture of potassium lactate and sodium diacetate) on the shelf-life of a pre-packaged cooked meat product. By means of a challenge test with a mixture of two Lactobacillus sakei strains and a Leuconostoc mesenteroides strain, it was observed that use of lactate/diacetate mixture enabled a 40% reduction of the salt content in this cooked meat product, whereas the microbial shelf-life was significantly increased.     

双乙酸钠对鲜湿米粉条保鲜和品质的影响

研究山梨酸钾、脱氢乙酸钠、双乙酸钠以及丙酸钙对鲜湿米粉条的保鲜效果,结果显示,双乙酸钠保鲜效果最优,添加量为0.2g/kg,残留量未检出。探讨了双乙酸钠对鲜湿米粉条感官要求、理化指标及微生物指标的影响,结果表明,添加双乙酸钠后,显著降低了霉菌总数,鲜湿米粉条外观、色泽、气味、口味等感官要求均有明显改善,水分、酸度等理化指标变化很小。     

Sensory characterisation and consumer acceptability of small calibre fermented sausages with 50% substitution of NaCl by mixtures of KCl and potassium lactate

The effect of six mixtures with 50% molar substitution of KCl (0–50%) and potassium lactate (0–50%) as NaCl substitutes in small calibre fermented sausages on some sensory parameters and on the acceptability was studied. Also, the relationship between sensory profile and consumer acceptability using external preference mapping was investigated. The results showed that as the K-lactate substitution increased, pH, sweetness, crumbliness and pastiness also increased, and piquantness, hardness, cohesiveness, ripened flavour, acid taste and saltiness decreased. However, the treatments prepared with a high level of salt substitution by KCl showed scores of sensory attributes similar to those of the control.Consumer segmentation showed differences in acceptability between genders, place of residence, educational level and age group. Consumers rejected fermented sausages with high K-lactate substitution but not those with a high KCl substitution. External preference mapping split consumers up into four clusters with different preference patterns. According to these results and from a sensory point of view, it is possible to achieve a reduction of 50% of NaCl in small calibre fermented sausages and to obtain a product acceptable to most consumers.     

Control of Listeriamonocytogenes on commercially-produced frankfurters prepared with and without potassium lactate and sodium diacetate and surface treated with lauric arginate using the Sprayed Lethality in Container (SLIC®) delivery method

Viability of Listeriamonocytogenes was monitored on frankfurters formulated with or without potassium lactate and sodium diacetate at a ratio of ca. 7:1 and treated with lauric arginate (LAE; 22 or 44 ppm) using the Sprayed Lethality in Container (SLIC®) delivery method. Without antimicrobials, pathogen numbers remained relatively constant at ca. 3.3 log CFU/package for ca. 30 d, but then increased to ca. 8.4 log CFU/package over 120 d. Regardless of whether or not lactate and diacetate were included, when treated with LAE, pathogen numbers decreased from ca. 3.3 log CFU/package to ca. 1.5 log CFU/package within 2 h, but then increased to 7.3 and 6.7 log CFU/package, respectively, after 120 d. When frankfurters were formulated with lactate and diacetate and treated with LAE, pathogen numbers decreased by ca. 2.0 log CFU/package within 2 h and remained relatively unchanged over the 120 d. These data confirm that LAE provides an initial lethality towards L. monocytogenes and when used in combination with reduced levels/ratio of lactate and diacetate as an ingredient for frankfurters provides inhibition throughout shelf life.