Concentrations Of Sodium Lactate Research Articles

Large-scale production of magnetosomes by chemostat culture of Magnetospirillum gryphiswaldense at high cell density

BackgroundMagnetotactic bacteria have long intrigued researchers because they synthesize intracellular nano-scale (40-100 nm) magnetic particles composed of Fe3O4, termed magnetosomes. Current research focuses on the molecular mechanisms of bacterial magnetosome formation and its practical applications in biotechnology and medicine. Practical applications of magnetosomes are based on their ferrimagnetism, nanoscale size, narrow size distribution, dispersal ability, and membrane-bound structure. However, the applications of magnetosomes have not yet been developed commercially, mainly because magnetotactic bacteria are difficult to cultivate and consistent, high yields of magnetosomes have not yet been achieved.ResultsWe report a chemostat culture technique based on pH-stat feeding that yields a high cell density of Magnetospirillum gryphiswaldense strain MSR-1 in an auto-fermentor. In a large-scale fermentor, the magnetosome yield was significantly increased by adjusting the stirring rate and airflow which regulates the level of dissolved oxygen (DO). Low concentration of sodium lactate (2.3 mmol l-1) in the culture medium resulted in more rapid cell growth and higher magnetosome yield than high concentration of lactate (20 mmol l-1). The optical density of M. gryphiswaldense cells reached 12 OD565 nm after 36 hr culture in a 42 L fermentor. Magnetosome yield and productivity were 83.23 ± 5.36 mg l-1 (dry weight) and 55.49 mg l-1 day-1, respectively, which were 1.99 and 3.32 times higher than the corresponding values in our previous study.ConclusionsCompared to previously reported methods, our culture technique with the MSR-1 strain significantly increased cell density, cell yield, and magnetosome yield in a shorter time window and thus reduced the cost of production. The cell density and magnetosome yield reported here are the highest so far achieved with a magnetotactic bacteria. Refinement of this technique will enable further increase of cell density and magnetosome yield.

Effect of Lactate Treatments on Survival of Food-Borne Pathogens in Frozen Shrimp (<i>Penaeus merguiensis</i>)

Problem statement: Sodium lactate treatments were evaluated for reducing population of pathogenic bacteria such as Salmonella enteritidis, E. coli O157:H7, Vibrio parahaemolyticus and Vibrio cholerae, inoculated on frozen shrimp (Penaeus merguiensis). Approach: Fresh shrimp were inoculated with the above pathogens, separately, at level of 105 CFU g-1 and appliedin sodium lactate solutions (NaL: 0.5% and 2.5% v/v) and 1% Lactic Acid (LA) plus 1.5% sodium lactate (as buffered lactic acid) followed by freezing. The samples were stored at -18°C and antimicrobial and organoleptical effects of the treatments were evaluated after 90 days. Results: Results indicated that there was synergistic effect between frozen storage combined with 2.5% (v/v) buffered LA which resulted in a great significant reductions (p≤0.05) approximately 5.11, 5.39, 2.86 and 2.66 log CFU g-1 in the number of colonies of V. cholerae, V. parahaemolyticus, S. enteritidis and E. coli O157:H7, respectively. On the other hand, although the effectiveness of sodium lactate increase with increased concentrations, however, there are sensory problems associated with increasing concentrations of sodium lactate. Conclusion/Recommendations: Therefore, 1.5% (v/v) sodium lactate plus 1.0% (v/v) Lactic Acid (buffered LA) was recommended to be used for frozen shrimps without adversely interfering with sensory quality.

POTENCIAL ALCALINIZANTE DA SOLUÇÃO DE RINGER COM LACTATO EM OVELHAS SADIAS

ALKALINIZING POWER OF LACTATED RINGER'S SOLUTION IN HEALTHY EWES The alkalinizing power of Lactated Ringer’s Solution (LRS) was searched in this work. Six crossbred healthy ewes, nonpregnant and nonlactating, weighting approximately 40 kg, received 4 L of LRS by 4 hours continuous intravenous infusion at a rate of 25 mL/kg/h. The venous blood samples were obtained before the infusion (0 hours), during the infusion (2 hours), at the end of the infusion (4 hours), and 2 hours after the end of the infusion (6 hours). Values of pH, pCO2, HCO3 - , TCO2, BE, Na + , K +, Cl - and lactate L were determined. The LRS induced mild increase in the alkali reserve confirming its low magnitude alkalinizing power, as a result of the small sodium lactate concentration present in the solution.

Glucose Prediction in the Interstitial Fluid Based on Infrared Absorption Spectroscopy Using Multi-component Analysis

Prediction of glucose concentration in the interstitial fluid (ISF) based on mid-infrared absorption spectroscopy was examined at the glucose fundamental absorption band of 1000 - 1500/cm (10 - 6.67 um) using multi-component analysis. Simulated ISF samples were prepared by including four major ISF components. Sodium lactate had absorption spectra that interfere with those of glucose. The rest NaCl, KCl and <TEX>$CaCl_2$</TEX> did not have any signatures. A preliminary experiment based on Design of Experiment, an optimization method, proved that sodium lactate influenced the prediction accuracy of glucose. For the main experiment, 54 samples were prepared whose glucose and sodium lactate concentration varied independently. A partial least squares regression (PLSR) analysis was used to build calibration models. The prediction accuracy was dependent on spectrum preprocessing methods, and Mean Centering produced the best results. Depending on calibration sample sets whose sodium lactate had different concentration levels, the standard error prediction (SEP) of glucose ranged <TEX>$17.19{\sim}21.02\;mg/dl$</TEX>.

Effectiveness of chitosan-coated plastic films incorporating antimicrobials in inhibition of Listeria monocytogenes on cold-smoked salmon

The objective of this study was to evaluate the efficacy of chitosan-coated plastic films incorporating five Generally Recognized as Safe (GRAS) antimicrobials (nisin, sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS) and sodium benzoate (SB)) against Listeria monocytogenes on cold-smoked salmon . Salmon samples were surface-inoculated with a five-strain cocktail of L. monocytogenes and packaged in chitosan-coated plastic films containing 500 IU/cm 2 of nisin, 9 mg/cm 2 of SL, 0.5 mg/cm 2 of SD, 0.6 mg/cm 2 of PS, or 0.2 mg/cm 2 of SB, and stored at room temperature (ca. 20 °C) for 10 days. The film incorporating SL was the most effective, completely inhibiting the growth of L. monocytogenes during 10 days of storage. L. monocytogenes in samples packaged in the other four antimicrobial films grew, but the increase in counts was lower than the control. The antilisterial efficacy of films containing lower concentrations of SL (2.3 mg/cm 2 and 4.5 mg/cm 2) and binary combinations SL, PS, SD, SB and nisin were subsequently evaluated. Among all the treatments, chitosan-coated plastic films with 4.5 mg/cm 2 SL, 4.5 mg/cm 2 SL–0.6 mg/cm 2 PS and 2.3 mg/cm 2 SL–500 IU/cm 2 nisin were the most effective. These three most effective antimicrobial films were then tested at refrigerated temperature. They completely inhibited the growth of L. monocytogenes on smoked salmon for at least 6 weeks. Chitosan-coated plastic films containing 4.5 mg/cm 2 SL can potentially assist the smoked-salmon processing industry in their efforts to control L. monocytogenes.

Co-metabolic degradation of bensulfuron-methyl in laboratory conditions

The present study deals with the degradation of bensulfuron-methyl by microorganisms cultured with different sources of carbon, nitrogen and phosphorus. Addition of carbon source accelerated the degradation of bensulfuron-methyl under co-metabolism process. Sodium lactate was the best carbon source for the degradation of bensulfuron-methyl, compared to other carbon sources studied, and the degradation ratio of bensulfuron-methyl reached 79.5%, whereas only 34.6 and 29.7% were removed in the presence of glucose and sucrose, respectively. Supplement of nitrogen source also enhanced degradation of bensulfuron-methyl. However, no significant differences were observed in the loss of bensulfuron-methyl between organic nitrogen and inorganic source. Phosphate buffer was supplemented into the media to maintain neutral conditions for the advantage of the strain growth since increase in pH value was observed. An orthogonal array design was applied to arrange main factors singled out for investigating the influence of factor and interaction between them on the degradation of bensulfuron-methyl. Statistical analysis showed that the concentration of sodium lactate, bensulfuron-methyl and inoculum size were the main effects, and the interaction of sodium lactate and bensulfuron-methyl was of statistical significance.

Characterization and synergistic antimicrobial activities of food-grade dilution-stable microemulsions against Bacillus subtilis

Abstract The physicochemical characterization of a food-grade glycerol monolaurate (GML)/ethanol/Tween 20/sodium lactate (SL)/water microemulsion system and the antimicrobial activities against Bacillus subtilis have been studied in this paper. The influence of ethanol and SL on oil solubilization capability was clearly reflected in the phase behavior of these systems. The addition of ethanol in GML/Tween 20/water system greatly improved the oil solubilization and induced the formation of a U-type microemulsion system, while a transition from U-type to S-type microemulsion system was observed with the increasing concentration of sodium lactate. Two microemulsion formulations were obtained and remained stable by physical stability studies. Antimicrobial results showed that the microemulsions were effective in inhibiting the viable bacteria cells and the bacteria growth. Later it was found that the microemulsions had synergistic antimicrobial activities with a major contribution of GML and the solubilization of SL enhanced the antimicrobial effects. This work indicated that microemulsions are promising delivery vectors for antimicrobial applications in food industry.

Modeling the Effect of Storage Atmosphere on Growth–No Growth Interface of Listeria monocytogenes as a Function of Temperature, Sodium Lactate, Sodium Diacetate, and NaCl

The effect of aerobic and anaerobic conditions on growth initiation by a 10-strain composite of Listeria monocytogenes (104 CFU/ml) was evaluated in tryptic soy broth with 0.6% yeast extract (TSBYE) as a function of 220 combinations of pH (3.82 to 7.42), sodium lactate (SL) (0 to 10%, vol/vol), and sodium diacetate (SD) (0 to 0.5%, wt/vol) at 10 or 30°C (a slightly abusive and the optimal growth temperature, both above the growth limiting range of 0 to 3°C for L. monocytogenes) in 96-well microplates. In addition, four probability-of-growth models were developed to quantify the effect of 346 aerobic and 346 anaerobic combinations of temperature (4 to 30°C), SL (0 to 6%, vol/vol), and SD (0 to 0.5%, wt/vol) in the presence of NaCl (0.5 or 2.5%, wt/vol) on the growth–no growth responses of the same L. monocytogenes strain composite, with a microplate reader. Growth responses were evaluated turbidimetrically (620 nm) every 5 days for a total of 40 days. Data were modeled with logistic regression to determine the growth–no growth interfaces. The minimum pH values at which growth of L. monocytogenes occurred were higher under anaerobic than under aerobic conditions, and this difference was more evident at 10°C or at higher SL and SD concentrations. The MIC of SD decreased with increasing SL levels. Anaerobic storage reduced the levels of SL-SD, allowing the growth of L. monocytogenes compared with aerobic storage, especially at low temperatures. In the presence of 2.5% NaCl, the MICs for SD were lower than those obtained with 0.5% NaCl, especially at 4 and 10°C, or in the presence of 5 to 6% SL. The developed models for anaerobic incubation showed good performance (80% successful predictions; i.e., in 40 of 50 comparisons) with independent data from studies on survival-growth of L. monocytogenes on meat products. The study provides quantitative data on the antimicrobial activity of SL (0 to 10%) and SD (0 to 0.5%), temperature (4 to 30°C), and pH (3.82 to 7.42) and on the probability of growth of L. monocytogenes under anaerobic or aerobic conditions in the presence of 0.5 or 2.5% NaCl, and hence, addresses important needs for risk assessment activities.

Separation and concentration of lactic acid by electro-electrodialysis

Reactive extraction combined with a modified two-phase electro-electrodialysis (MTPEED) process shows a strong potential in the recovery and concentration of lactic acid without generating a salt waste. In this paper, an electro-electrodialysis (EED) process was designed with mixed lactic acid and sodium lactate aqueous solution as catholyte to simulate this MTPEED process. The immediate factors affecting the current efficiency, cell voltage and energy consumption were investigated. The optimization of operating conditions was also discussed. The lowest cell voltage was reached when the sodium lactate concentration was about 1.7 mol L −1. The current efficiency was kept near 100% before lactic acid in the catholyte was exhausted. When the current density was 160.7 A m −2, a representative specific energy consumption of the MTPEED process was 1.404 kWh/kg lactic acid, far lower than 2.961 kWh/kg lactic acid of a comparable EED process with sodium lactate aqueous solution as catholyte. The cell voltage of the MTPEED process was also affected by the phase ratio of the organic phase to the water phase. The lower phase ratio is preferred.

Elaboração de empanado a partir da corvina (Micropogonias furnieri)

O trabalho teve por objetivo elaborar empanado a partir da corvina (Micropogonias furnieri). Os pescados foram medidos, pesados, avaliados quanto ao frescor através do pH e bases voláteis totais (BVT) e determinada sua composição proximal. As corvinas apresentaram um tamanho e peso médio de 28,0 cm e 268,3 g, respectivamente. O pH e as concentrações de N-BVT dos exemplares utilizados encontraram-se dentro dos limites indicados pela legislação brasileira. A composição proximal da corvina foi 78,7% de umidade, 18,8% de proteína, 1,2% de cinza e 1,1% de gordura. A partir de testes preliminares definiu-se a formulação base, a qual se utilizou para determinar o tempo de pré-fritura do produto, que foi de 30 segundos. Para definir a formulação final do produto, foi realizado um planejamento fatorial completo 2³, com triplicata dos pontos centrais, variando-se o tempo de lavagem do músculo (0; 15 e 30 segundos), concentração de lactato de sódio (0; 0,8 e 1,6%) e de leite em pó (0; 1 e 2%). As variáveis respostas foram a CRA, umidade, proteína e gordura, bem como a qualidade geral sensorial e os atributos de aparência, crocância, textura e sabor. Através dos resultados, foi possível verificar que o tempo de lavagem do músculo foi o fator de maior influência nas características sensoriais do produto, enquanto que para as características físico-químicas observou-se que estas foram influenciadas pelos três fatores estudados. Dessa forma, a formulação selecionada foi a submetida à condição de: 30 segundos de lavagem do músculo, 2% de leite em pó e ausência de lactato de sódio.

Thermal, mechanical and water vapor barrier properties of sodium caseinate films containing antimicrobials and their inhibitory action on Listeria monocytogenes

Antimicrobial films were prepared by incorporating different concentrations of sodium lactate (Na lactate), potassium sorbate (K sorbate) and nisin into sorbitol-plasticized sodium caseinate (SC) films. The impact of antimicrobial compounds on the water sorption, water vapor barrier properties and thermo-mechanical behavior of SC films was investigated. Furthermore, their antimicrobial effectiveness against Listeria monocytogenes was studied as a function of antimicrobial concentration. The water content and water vapor permeability (WVP) of SC films increased with increasing Na lactate and K sorbate concentration, with Na lactate-containing SC films showing higher capacity to absorb moisture and greater WVP values than the films containing K sorbate. On the other hand, nisin addition did not cause significant changes in the water uptake and WVP of SC films. The incorporation of Na lactate and K sorbate affected in different way the glass transition temperature ( T g defined as tan δ peak) of antimicrobial SC films, with Na lactate increasing and the K sorbate depressing the T g of the system. The addition of increasing Na lactate and K sorbate concentration resulted in reduction of Young modulus ( E) and maximum tensile strength ( σ max) and increasing of elongation at break (% EB) suggesting that both antimicrobials acted as plasticizers for the SC films. Nisin-containing SC films were the most effective in reducing growth of L. monocytogenes, followed by K sorbate-impregnated SC films, whereas films containing Na lactate were slightly effective in this respect and only at the higher concentration (40% w/w film dry basis). The results indicated that for effective applications of antimicrobial coatings in foods, sufficient knowledge is required not only on the independent properties of the coating film and the antimicrobial compound but also on their interactions.

A Predictive Model To Describe the Effects of Temperature, Sodium Lactate, and Sodium Diacetate on the Inactivation of a Serotype 4b Strain of Listeria monocytogenes in a Frankfurter Slurry

A modified Gompertz equation was used to model the effects of temperature (55, 60, and 65°C), sodium lactate (0, 2.4, and 4.8%), and sodium diacetate (0, 0.125, and 0.25%) on inactivation of Listeria monocytogenes strain MFS 102 (serotype 4b) in frankfurter slurry. The effects of these factors were determined on the shouldering region (parameter A), maximum death rate (parameter B), and tailing region (parameter C) of microbial inactivation curves. Increased temperature or sodium diacetate concentrations increased the death rate, whereas increased sodium lactate concentrations decreased heat resistance. Complex two-way interactive effects were also observed. As both temperature and sodium lactate increased, the death rate decreased; however, as temperature and sodium diacetate increased, the death rate increased. The effect of the interaction between sodium lactate and sodium diacetate on the maximum death rate varied with temperature. Increases in both acidulants at temperatures above 56.7°C decreased the death rate, whereas at temperatures below 56.7°C, increases in both acidulants increased the death rate. To test for significant differences between treatments, D-values were calculated and compared. This comparison revealed that, in general, sodium lactate increased heat resistance and sodium diacetate decreased heat resistance of L. monocytogenes. This information is important for reducing and minimizing contamination during postprocessing thermal treatments.

Eye irritation of low-irritant cosmetic formulations: correlation of in vitro results with clinical data and product composition

Alternative methods to the Draize eye irritation test, such as the hen’s egg test-chorioallantoic membrane (HET-CAM) or the bovine corneal opacity and permeability (BCOP) tests, are currently used to evaluate the irritant potential of cosmetic or consumer products. Although, for strong irritants, the results of these tests correlate well with those of the Draize test, they appear to be less suited to identify mild irritants. In order to improve the sensitivity of alternative eye irritation tests, we developed a novel method that uses a human corneal epithelial cell line (CEPI), and the endpoints of cytotoxicity and IL-8 release. Twelve make-up removers were assessed by the HET-CAM, BCOP and CEPI tests, as well as in a clinical in-use test under ophthalmological control after their application to the external eye lid. In addition, we investigated the impact of osmolality and raw material composition on in vitro and clinical results and compared the in vitro results with those of clinical studies. Overall, although HET-CAM results were unrelated to eye discomfort and adverse clinical signs, they correlated mainly with the presence and concentration of surfactants in the test articles. BCOP scores were unrelated to clinical signs, but related mainly to glycol and sodium lactate content and concentration in the test articles. Cytotoxicity in CEPI mainly correlated with presence and concentrations of surfactants, and IL-8 release to clinical signs and/or glycol and sodium lactate concentrations. Overall, IL-8 release appeared to be the most sensitive and reliable endpoint to predict human eye tolerance to mildly irritant products. Although our results suggest that the IL-8 assay appears to be a promising screen for borderline-irritant formulations, further experiments are required to confirm and validate these preliminary results.

Predictive thermal inactivation model for effects of temperature, sodium lactate, NaCl, and sodium pyrophosphate on Salmonella serotypes in ground beef.

Analyses of survival data of a mixture of Salmonella spp. at fixed temperatures between 55 degrees C (131 degrees F) and 71.1 degrees C (160 degrees F) in ground beef matrices containing concentrations of salt between 0 and 4.5%, concentrations of sodium pyrophosphate (SPP) between 0 and 0.5%, and concentrations of sodium lactate (NaL) between 0 and 4.5% indicated that heat resistance of Salmonella increases with increasing levels of SPP and salt, except that, for salt, for larger lethalities close to 6.5, the effect of salt was evident only at low temperatures (<64 degrees C). NaL did not seem to affect the heat resistance of Salmonella as much as the effects induced by the other variables studied. An omnibus model for predicting the lethality for given times and temperatures for ground beef matrices within the range studied was developed that reflects the convex survival curves that were observed. However, the standard errors of the predicted lethalities from this models are large, so consequently, a model, specific for predicting the times needed to obtained a lethality of 6.5 log(10), was developed, using estimated results of times derived from the individual survival curves. For the latter model, the coefficient of variation (CV) of predicted times range from about 6 to 25%. For example, at 60 degrees C, when increasing the concentration of salt from 0 to 4.5%, and assuming that the concentration of SPP is 0%, the time to reach a 6.5-log(10) relative reduction is predicted to increase from 20 min (CV = 11%) to 48 min (CV = 15%), a 2.4 factor (CV = 19%). At 71.1 degrees C (160 degrees F) the model predicts that more than 0.5 min is needed to achieve a 6.5-log(10) relative reduction.

Evaluation of a challenge testing protocol to assess the stability of ready-to-eat cooked meat products against growth of Listeria monocytogenes

Challenge testing of ready-to-eat (RTE) foods with Listeria monocytogenes is recommended to assess the potential for growth. The present study was undertaken to evaluate a protocol for challenge testing applied to RTE cooked meat products. In order to choose L. monocytogenes strains with a representative behaviour, initially, the variability of the response of multiple L. monocytogenes strains of human and food origin to different stress and growth conditions was established. The strains were not inhibited in their growth at moderate acid pH (5.25) and the four strains tested in particular showed a similar acid-adaptive response. Growth of the various strains under four different combined stress conditions indicated that no L. monocytogenes strain had consistently significant longer or shorter lag phase or higher or lower maximum specific growth rates. The effect of choice of strain and history (pre-incubation temperature 7 or 30 °C) on growth of L. monocytogenes under optimum conditions (Brain Heart Infusion, BHI) and modified BHI simulating conditions of cooked ham and paté was studied. In general, all four L. monocytogenes strains behaved similarly. In BHI, no difference in lag phase was observed for the cold-adapted and standard inoculum, whereas in BHI adjusted to ham and pâté conditions, a ca. 40-h reduction of the lag phase was noted for the cold-adapted inoculum. Subsequently, microbial challenge testing of L. monocytogenes in modified atmosphere packaged sliced cooked ham and paté was performed. A mixed inoculum of four L. monocytogenes strains and an inoculum level of ca. 1–10 cfu/g was used. On vacuum packed sliced cooked ham, the concentration of 100 cfu/g, the safety limit considered as low risk for causing listeriosis, was exceeded after 5 days whereas ca. 10 5 cfu/g were obtained after 14 days when also LAB spoilers reached unacceptable numbers (ca. 10 7 cfu/g) whether standard or cold-adapted inoculum was used. The concentration of sodium lactate determined the opportunities for growth of L. monocytogenes in pâté. If growth of L. monocytogenes in pâté was noticed, the threshold of 100 cfu/ml was crossed earlier for the cold-adapted inoculum compared to the standard inoculum.

The effects of sodium lactate and starter cultures on pH, lactic acid bacteria, Listeria monocytogenes and Salmonella spp. levels in pure chicken dry fermented sausage

Two starter cultures ( A and B) and seven sodium lactate concentrations were evaluated for chicken raw dry-fermented sausage processing. Starter culture B contained more lactic acid bacteria and less staphylococci than starter A. Their effects on acidification and inhibition of pathogens ( Listeria monocytogenes and Salmonella spp.) were monitored. Starter culture B grew faster and was less inhibited by sodium lactate, thus inducting a faster and more important pH drop into the sausages. With lower pH, sausages processed with B starter were less contaminated by Listeria monocytogenes. The type of starter was found to influence the end-product pH, lactic acid bacteria content and extent of Listeria monocytogenes contamination. A 30-member panel did not note differences between sausages processed with the different starter cultures when lactate was added. Adding sodium lactate to the sausage mix reduced the pH drop in the dry sausage product. This acidification inhibiting effect of sodium lactate was greater for A. Sodium lactate significantly inhibited lactic acid bacteria development but did not reduce Listeria monocytogenes contamination frequency of the batches, unlike in many literature data. Sodium lactate may however control the acidification of the sausage processed with starter B, in order to obtain moderately acidified fermented sausages. A simple kinetic model was applied to our data. The sodium lactate content and especially the type of starter culture often had a significant effect on the four parameters of this empirical model (lag time, acidification time, initial and final pH).

Growth of Listeria monocytogenes in modified atmosphere packed cooked meat products: a predictive model

Predictive models for the influence of intrinsic and extrinsic parameters relevant for gas-packed, cooked meat products on the growth parameters (maximum specific growth rate and the lag phase ) of Listeria monocytogenes were developed. Two types of models were compared, i.e. extended Ratkowsky models and response surface models. Temperature, water activity, concentration of sodium lactate (SL) and dissolved CO2in the aqueous phase were considered as the relevant parameters influencing the growth of L. monocytogenes in gas-packed, cooked meat products and were included in the models. The concentration of CO2in the aqueous phase of the food was chosen as the determinative inhibitory factor of modified atmospheres. All four investigated independent variables did influence significantly the growth parameters of L. monocytogenes. Interactions between temperature and CO2and especially between CO2and Na–lactate were observed. The model was validated in real gas-packed, cooked meat products and was then combined with previously developed models for spoilage of gas-packed, cooked meat products to determine the ‘Risk Areas’ for these type of food products. Low water activity cooked meat products supported outgrowth of L. monocytogenes before spoilage had occurred, unless Na–lactate and CO2were applied as extra hurdles.

Conversion of sodium lactate to lactic acid with water-splitting electrodialysis.

The conversion of sodium lactate to lactic acid with water-splitting electrodialysis was investigated. One way of reducing the power consumption is to add a conductive layer to the acid compartment. Doing this reduced the power consumption by almost 50% in a two-compartment cell, whereas the electric current efficiency was not affected at all. Three different solutions were treated in the electrodialysis unit: a model solution with 70 g/L of sodium lactate and a fermentation broth that had been prefiltered two different ways. The fermentation broth was either filtered in an open ultrafiltration membrane (cut-off of 100,000 Dalton) in order to remove the microorganisms or first filtered in the open ultrafiltration membrane and then in an ultrafiltration membrane with a cut-off of 2000 Dalton to remove most of the proteins. The concentration of sodium lactate in the fermentation broth was 70 g/L, as well. Organic molecules present in the broth (peptides and similar organic material) fouled the membranes and, therefore, increased power consumption. Power consumption increased more when permeate from the more open ultrafiltration membrane was treated in the electrodialysis unit than when permeate from the membrane with the lower cut-off was treated, since there was a higher amount of foulants in the former permeate. However, the electrodialysis membranes could be cleaned efficiently with a 0.1 M sodium hydroxide solution.

Carbon Dioxide-Sustained Adsorption of Lactic Acid at pH &gt; pKa of the Acid

Experimental data are presented for batch and fixed-bed adsorption of lactic acid from aqueous sodium lactate solutions onto the tertiary amine sorbents, Dowex MWA-1 and Amberlite IRA-35, in the presence of carbon dioxide. The effects of carbon dioxide pressure and sodium lactate concentration on lactate uptake capacity were measured. A simple complexation model, which includes chemical-equilibria and mass- and charge-balance equations, was developed to describe the system. There are no fitted parameters in the model. The model predictions compare well with batch adsorption data.

Sodium lactate affects sensory and objective characteristics of tray-packed broiler chicken breast meat

The objective of this study was to determine the antimicrobial properties of sodium lactate solutions adjusted to various pH values. The effectiveness of sodium lactate increases with increased concentrations; however, there are off-flavor development problems associated with increasing concentrations of sodium lactate above 2.0%. This study evaluated the effects of 2% sodium lactate treatments, adjusted to various pH values, on sensory characteristics, instrumental texture, and microbial populations of tray-packed broiler breast meat. Breast meat was treated with either tap water (pH 7.85) or 2% sodium lactate solutions (pH 7.30, 5.50, 5.00, 4.50, and 4.00) and stored at 2 +/- 1 C for 12 d. Approximately 15% of the panelists reported acidic aftertastes in samples treated with pH 5.00 sodium lactate solutions, and 10% of the panelists reported slight sodium or metallic off-flavor in all samples treated with sodium lactate. Instrumental texture measurements were similar (P > 0.05) for all treatments. Sodium lactate (pH 7.30 and 5.50) enhanced (P < 0.05) cooking yields and retarded the growth of spoilage bacteria (pH 5.50 and 5.00). Due to the development of severe discoloration and intense acidic off-odors and -flavors, testing was not conducted on samples treated with pH 4.50 and 4.00 sodium lactate solutions.