Resistance of Acid-Adapted Salmonellae to Organic Acid Rinses on Beef†

1995 ◽  
Vol 58 (9) ◽  
pp. 973-976 ◽  
Author(s):  
J. S. DICKSON ◽  
M. R. KUNDURU
Keyword(s):  
Organic Acid ◽  
Parent Strain ◽  
Good Growth ◽  
Acid Solutions ◽  
Bacterial Populations ◽  
Acid Adaptation ◽  
Ph Values ◽  
Atcc Strain ◽  
Lean Beef ◽  
Acidic Conditions

Four strains of salmonellae, including three bovine isolates and an ATCC strain, were adapted to growth in acidic conditions by sequential transfer in tryptic soy broth with reduced pH values. The cultures were transferred until good growth (approximately log107 CFU/ml) was obtained within 24 h at 37°C at pH 5.0. Lean beef tissue was inoculated by immersion into either the acid-adapted or the homologous parent strain of each bacterium. The inoculated tissue was rinsed for 10s in 1.5% or 3.0% lactic acid solutions at 23°C or 55°C. Reductions in bacterial populations were compared between the parent and acid-adapted strains to determine if the acid-adapted strains were more resistant to the organic acid rinses. Acid-adapted strains had either equal or greater sensitivity to organic acid rinses than their homologous parent strains, indicating that acid adaptation did not result in bacteria which were resistant to organic acid rinses. Acid-adapted strains had significantly lower D55°C− values than their homologous parent strains.

Acid Adaptation Does Not Promote Survival or Growth of Listeria monocytogenes on Fresh Beef following Acid and Nonacid Decontamination Treatments

2003 ◽  
Vol 66 (6) ◽  
pp. 985-992 ◽  
Author(s):  
J. S. IKEDA ◽  
J. SAMELIS ◽  
P. A. KENDALL ◽  
G. C. SMITH ◽  
J. N. SOFOS
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Residual Activity ◽  
Hot Water ◽  
Acid Solutions ◽  
Acid Adaptation ◽  
Lean Beef ◽  
Water Based ◽  
Survival And Growth

The objective of this study was to evaluate the survival and growth of acid-adapted and nonadapted Listeria monocytogenes inoculated onto fresh beef subsequently treated with acid or nonacid solutions. Beef slices (2.5 by 5 by 1 cm) from top rounds were inoculated with acid-adapted or nonadapted L. monocytogenes (4.6 to 5.0 log CFU/cm2) and either left untreated (control) or dipped for 30 s in water at 55°C, water at 75°C, 2% lactic acid at 55°C, or 2% acetic acid at 55°C. The beef slices were vacuum packaged and stored at 4 or 10°C and were analyzed after 0, 7, 14, 21, and 28 days of storage. Dipping in 75°C water, lactic acid, and acetic acid resulted in immediate pathogen reductions of 1.4 to 2.0, 1.8 to 2.6, and 1.4 to 2.4 log CFU/cm2, respectively. After storage at 10°C for 28 days, populations of L. monocytogenes on meat treated with 55°C water increased by ca. 1.6 to 1.8 log CFU/cm2. The pathogen remained at low population levels (1.6 to 2.8 log CFU/cm2) on acid-treated meat, whereas populations on meat treated with 75°C water increased rapidly, reaching levels of 3.6 to 4.6 log CFU/cm2 by day 14. During storage at 4°C, there was no growth of the pathogen for at least 21 days in samples treated with 55 and 75°C water, and periods of no growth were longer for acid-treated samples. There were no differences between acid-adapted and nonadapted organisms across treatments with respect to survival or growth. In conclusion, the dipping of meat inoculated with L. monocytogenes into acid solutions reduced and then inhibited the growth of the pathogen during storage at 4 and 10°C, while dipping in hot water allowed growth despite initial reductions in pathogen contamination. The results of this study indicate a residual activity of acid-based decontamination treatments compared with water-based treatments for refrigerated (4°C) or temperature-abused (10°C) lean beef tissue in vacuum packages, and these results also indicate that this activity may not be counteracted by prior acid adaptation of L. monocytogenes.

Inactivation of Salmonella during Drying and Storage of Roma Tomatoes Exposed to Predrying Treatments Including Peeling, Blanching, and Dipping in Organic Acid Solutions

2004 ◽  
Vol 67 (7) ◽  
pp. 1344-1352 ◽  
Author(s):  
YOHAN YOON ◽  
JARRET D. STOPFORTH ◽  
PATRICIA A. KENDALL ◽  
JOHN N. SOFOS
Keyword(s):  
Acid Solution ◽  
Organic Acid ◽  
Acid Solutions ◽  
Pathogen Inactivation ◽  
Drying Process ◽  
Bacterial Populations ◽  
Process Use ◽  
Bacterial Enumeration ◽  
And Storage ◽  
G Prior

The objective of this study was to evaluate the influence of predrying treatments, i.e., peeling, blanching prior to inoculation, and dipping in organic acid solutions, on inactivation of Salmonella during drying (60°C for 14 h) and aerobic storage (25°C for 28 days) of inoculated (five-strain composite, 7.1 to 7.4 log CFU/g) Roma tomato halves. Four predrying treatments groups were established. One group received no treatment (C). In the other three groups, unpeeled-unblanched, unpeeled-blanched (steam blanched at 88°C for 3 min), peeled-unblanched, and peeled-blanched tomato halves were immersed for 10 min in water (W), ascorbic acid solution (AA; 3.40%, pH 2.48), or citric acid solution (CA; 0.21%, pH 2.51). Appropriate dilutions of homogenized tomato samples were spread plated on tryptic soy agar with 0.1% pyruvate and XLT4 agar for bacterial enumeration during drying and storage. Ten minutes of immersion in W, AA, or CA reduced bacterial populations by 0.7 to 1.6 log CFU/g. After 14 h of dehydration, total log reductions in the populations of bacteria were 3.2 to 4.5 (C), 3.7 to 4.9 (W), >5.6 to >6.1 (AA), and 4.5 to 5.5 (CA) log CFU/g, depending on type of agar used and condition of tomato samples. During drying and storage, the order of pathogen inactivation for predrying dipping treatments was AA > CA > W > C, with AA and CA rendering bacterial populations below detectable levels (<1.3 log CFU/g) prior to storage and between 7 and 14 days of storage, respectively. The results also indicated that peeling and blanching of tomatoes prior to inoculation may not necessarily affect destruction of Salmonella during the drying process. Use of predrying acid dipping treatments of tomatoes, especially in AA, may improve destruction of Salmonella during the dehydration process.

Genetics of Acid Adaptation in Oral Streptococci

2001 ◽  
Vol 12 (4) ◽  
pp. 301-314 ◽  
Author(s):  
Robert G. Quivey ◽  
Wendi L. Kuhnert ◽  
Kristina Hahn
Keyword(s):  
Adaptive Systems ◽  
Future Research ◽  
Gram Negative Bacteria ◽  
Oral Streptococci ◽  
Microbial Competition ◽  
Acid Adaptation ◽  
Ph Values ◽  
Plaque Ph ◽  
The Face ◽  
Acidic Conditions

A growing body of information has provided insights into the mechanisms by which the oral streptococci maintain their niches in the human mouth. In at least one case, Streptococcus mutans, the organism apparently uses a panel of proteins to survive in acidic conditions while it promotes the formation of dental caries. Oral streptococci, which are not as inherently resistant to acidification, use protective schemes to ameliorate acidic plaque pH values. Existing information clearly shows that while the streptococci are highly related, very different strategies have evolved for them to take advantage of their particular location in the oral cavity. The picture that emerges is that the acid-adaptive regulatory mechanisms of the oral streptococci differ markedly from those used by Gram-negative bacteria. What future research must determine is the extent and complexity of the acid-adaptive systems in these organisms and how they permit the organisms to maintain themselves in the face of a low-pH environment and the microbial competition present in their respective niches.

scholarly journals Immobilization of Cd, Zn, and Pb from Soil Treated by Limestone with Variation of pH Using a Column Test

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Sung-Wook Yun ◽  
Chan Yu
Keyword(s):  
South Korea ◽  
Water Systems ◽  
Metal Mobility ◽  
Acid Solutions ◽  
Test Results ◽  
Column Test ◽  
Acidic Solutions ◽  
Ph Values ◽  
Metal Mines ◽  
Site Restoration

Decades of mining in South Korea have resulted in the contamination of large amounts of soil by metals. The most feasible approach to site restoration requires the use of a stabilization agent to reduce metal mobility. This study examined the leaching characteristics of limestone used as a stabilization agent when subjected to solutions of differing pH. In a laboratory-scale column test, solutions with pH values of 3.5, 4.6, and 5.6, representing acidic to nonacidic rainfall, were applied to soil mixed with limestone. Test results indicate that metal components can be released with the addition of acidic solutions, even if the soil is highly alkaline. Cd and Zn, in particular, exhibited abrupt or continuous leaching when exposed to acid solutions, indicating the potential for contamination of water systems as metal-laden soils are exposed to the slightly acidic rainfall typical of South Korea. Treatment using stabilization agents such as limestone may reduce leaching of metals from the contaminated soil. Stabilizing metal-contaminated farmland is an economical and feasible way to reduce pollutants around abandoned metal mines.

Sulfite Oxidation in Organic Acid Solutions

1982 ◽  
pp. 173-189 ◽  
Author(s):  
D. B. NURMI ◽  
J. W. OVERMAN ◽  
J. ERWIN ◽  
J. L. HUDSON
Keyword(s):  
Organic Acid ◽  
Acid Solutions ◽  
Sulfite Oxidation

Removal of Dyes from Aqueous Solutions by Adsorption on Chrome-Tanned Solid Wastes Generated in the Leather Industry

2003 ◽  
Vol 38 (2) ◽  
pp. 393-411 ◽  
Author(s):  
Soufiane Tahiri ◽  
Ali Messaoudi ◽  
Abderrahman Albizane ◽  
Mohamed Azzi ◽  
Mohamed Bouhria ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Operating Conditions ◽  
Solid Wastes ◽  
Cationic Dyes ◽  
Optimum Operating ◽  
Leather Industry ◽  
Anionic Dyes ◽  
Ph Values ◽  
Acidic Conditions ◽  
Dyes Adsorption

Abstract In this work, the ability of chrome shavings and of crust leather buffing dusts to remove dyes from aqueous solutions has been studied. Buffing dusts proved to be a much better adsorbent than chrome shavings for cationic dyes. The adsorption of anionic dyes is very important on two studied wastes. The pH has an obvious influence on the adsorption of dyes. Adsorption of cationic dyes is less favourable under acidic conditions (pH <3.5) and at high pH values (pH >10.5). The adsorption of anionic dyes on both adsorbents is more favourable under acidic conditions (pH <3). The adsorption on chrome shavings is improved by the use of finer particles. The kinetic adsorption was also studied. Adsorption isotherms, at the optimum operating conditions, were determined. Adsorption follows the Langmuir model. The isotherm parameters have been calculated. The column technique could be applied to treat significant volumes of solutions.

The tamoxifen cation reacts to give indene products

2000 ◽  
Vol 78 (9) ◽  
pp. 1186-1193
Author(s):  
Cristina Sanchez ◽  
Robert A McClelland
Keyword(s):  
Intramolecular Cyclization ◽  
Phenyl Ring ◽  
Irreversible Process ◽  
Total Yield ◽  
Cellular Systems ◽  
Acid Solutions ◽  
Allylic Cation ◽  
Super Acid ◽  
Acidic Conditions

The tamoxifen carbocation (Ph(Ar)C=CPh-CH+-CH3, Ar = 4-Me2NCH2CH2OC6H4) is generated from acetate and sulfate precursors by SN1 ionization in water. The cation exists in (E) and (Z) forms which equilibrate before reaction. The major products are the α-hydroxytamoxifens Ph(Ar)C=CPh-CHOH-CH3, both (E) 64% and (Z) 29%, with the ratio independent of the configuration of the starting ester. Two minor products with a total yield of 7% account for the rest of the products. These have been characterized as indenes derived from intramolecular cyclization, a 4.5% yield of the indene derived from cyclization into the Ar ring with 2.5% due to cyclization into the phenyl ring. Experiments in acid solutions (0.01-0.1 M HCl) starting with pure (E)- or (Z)-α-hydroxytamoxifen reveal that the two alcohols equilibrate. This occurs by H+-catalyzed formation of the carbocation followed by water capture. Occurring about 10-fold slower than this isomerization is an irreversible process resulting in the two indenes. This cyclization will result in the destruction of the α-hydroxytamoxifens upon exposure to acidic conditions and also makes the direct observation of the tamoxifen carbocation under super-acid conditions difficult, if not impossible. The indenes do form in low yield whenever the tamoxifen carbocation is generated from an SN1 precursor. Thus these products could serve as markers for the formation of the tamoxifen carbocation in cellular systems or in in vivo experiments.Key words: carbocation, indene, allylic cation, isomerization.

Control of Listeria monocytogenes on Frankfurters with Antimicrobials in the Formulation and by Dipping in Organic Acid Solutions

2004 ◽  
Vol 67 (11) ◽  
pp. 2456-2464 ◽  
Author(s):  
I. M. BARMPALIA ◽  
I. GEORNARAS ◽  
K. E. BELK ◽  
J. A. SCANGA ◽  
P. A. KENDALL ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Organic Acid ◽  
The United States ◽  
Acid Solutions ◽  
Overall Acceptability ◽  
Bactericidal Effects ◽  
Yeasts And Molds ◽  
And Storage

The antilisterial activity of sodium lactate (SL) and sodium diacetate (SD) was evaluated in a frankfurter formulation and in combination with a dipping treatment into solutions of lactic acid or acetic acid after processing and inoculation. Pork frankfurters were formulated with 1.8% SL or 0.25% SD or combinations of 1.8% SL with 0.25 or 0.125% SD. After processing, frankfurters were inoculated (2 to 3 log CFU/cm2) with a 10-strain composite of Listeria monocytogenes and left undipped or were dipped (2 min) in 2.5% solutions of lactic acid or acetic acid (23 ± 2°C) before vacuum packaging and storage at 10°C for 40 days. Total microbial populations and L. monocytogenes, lactic acid bacteria, and yeasts and molds were enumerated during storage. Sensory evaluations also were carried out on frankfurters treated and/or formulated with effective antimicrobials. The combination of 1.8% SL with 0.25% SD provided complete inhibition of L. monocytogenes growth throughout storage. Dipping in lactic acid or acetic acid reduced initial populations by 0.7 to 2.1 log CFU/cm2, but log CFU/cm2. For samples containing single antimicrobials and dipped in lactic acid or acetic acid, L. monocytogenes growth was completely inhibited or reduced over 12 and 28 days, respectively, whereas final populations were lower (P < 0.05) than those in undipped samples of the same formulations. Bactericidal effects during storage (reductions of 0.6 to 1.0 log CFU/cm2 over 28 to 40 days) were observed in frankfurters containing combinations of SL and SD that were dipped in organic acid solutions. Inclusion of antimicrobials in the formulation and/or dipping the product into organic acid solutions did not affect (P > 0.05) the flavor and overall acceptability of products compared with controls. The results of this study may be valuable to meat processors as they seek approaches for meeting new regulatory requirements in the United States.

scholarly journals Large Differences in Urinary Benzene Metabolite S-Phenylmercapturic Acid Quantitation: A Comparison of Five LC–MS-MS Methods

2020 ◽  
Author(s):  
Denise S Tevis ◽  
Andrew Willmore ◽  
Deepak Bhandari ◽  
Brett Bowman ◽  
Chloe Biren ◽  
...  
Keyword(s):  
Human Urine ◽  
Analytical Methods ◽  
Urine Samples ◽  
Genotoxic Carcinogen ◽  
Human Urine Samples ◽  
Ph Values ◽  
Wide Range ◽  
Acidic Conditions ◽  
Hematological Abnormalities ◽  
Reference Samples

Abstract Benzene is a known genotoxic carcinogen linked to many hematological abnormalities. S-phenylmercapturic acid (PHMA, N-acetyl-S-(phenyl)-L-cysteine, CAS# 4775-80-8) is a urinary metabolite of benzene and is used as a biomarker to assess benzene exposure. Pre-S-phenylmercapturic acid (pre-PHMA) is a PHMA precursor that dehydrates to PHMA at acidic pH. Published analytical methods that measure urinary PHMA adjust urine samples to a wide range of pH values using several types of acid, potentially leading to highly variable results depending on the concentration of pre-PHMA in a sample. Information is lacking on the variation in sample preparation among laboratories regularly measuring PHMA and the effect of those differences on PHMA quantitation in human urine samples. To investigate the differences in PHMA quantitation, we conducted an inter-laboratory comparison that included the analysis of 50 anonymous human urine samples (25 self-identified smokers and 25 self-identified non-smokers), quality control samples and commercially available reference samples in five laboratories using different analytical methods. Observed urinary PHMA concentrations were proportionally higher at lower pH, and results for anonymous urine samples varied widely among the methods. The method with the neutral preparation pH yielded results about 60% lower than the method using the most acidic conditions. Samples spiked with PHMA showed little variation, suggesting that the variability in results in human urine samples across methods is driven by the acid-mediated conversion of pre-PHMA to PHMA.

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