Acidified Sodium Chlorite Solution Research Articles

Facile fabrication of rape straw biomass fiber/β-CD/Fe3O4 as adsorbent for effective removal of ibuprofen

Wastewater containing pharmaceuticals can be bioaccumulated, posing a potential risk to drinking water, human health, and ecosystems. In order to make the adsorption process more suitable for actual application, rape straw biomass fiber (treated by an acidified sodium chlorite solution, 5%) and Fe3O4 embedded β-CD to prepare a novel adsorbent (RSBCDF), which was used for the removal of ibuprofen (IBP) from aqueous solution. The RSBCDF was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) measurements, scanning electron microscopy (SEM), and zeta potential measurements. The synthesized adsorbent was studied with regard to IBP removal percent under different adsorption conditions such as varying initial pH levels (4–10), initial ibuprofen concentrations (20−160 mg/L), contact time (5−150 min), and the dosage of adsorbent (10−100 mg) via batch adsorption experiments. The adsorption kinetics, thermodynamics, and isotherms were also investigated. The IBP adsorption behaviour followed a pseudo-second-order kinetic model and the Freundlich isotherm model. The maximum adsorption capacity obtained for ibuprofen was 48.29 mg/g. The values of Gibbs free energy change were negative (-2.58∼-3.56KJ/mol), suggesting that the process of ibuprofen adsorption onto adsorbent was spontaneous. The positive value of standard enthalpy change (12.09 kJ/mol) indicated that the adsorption process was endothermic. The obtained results prove that RSBCDF is a proficient and economically suitable material for removing IBP from water environments.

Identifying the chloroperoxyl radical in acidified sodium chlorite solution.

The present study identified the active radical species in acidic sodium chlorite and investigated the feasibility of quantifying these species with the diethylphenylenediamine (DPD) method. Electron spin resonance (ESR) spectroscopy was used to identify the active species generated in solutions containing sodium chlorite (NaClO2). The ESR signal was directly observed in an acidified sodium chlorite (ASC) aqueous solution at room temperature. This ESR signal was very long-lived, indicating that the radical was thermodynamically stable. The ESR parameters of this signal did not coincide with previously reported values of the chlorine radical (Cl●) or chlorine dioxide radical (O = Cl●-O and O = Cl-O●). We refer to this signal as being from the chloroperoxyl radical (Cl-O-O●). Quantum chemical calculations revealed that the optimal structure of the chloroperoxyl radical is much more thermodynamically stable than that of the chlorine dioxide radical. The UV-visible spectrum of the chloroperoxyl radical showed maximum absorbance at 354 nm. This absorbance had a linear relationship with the chloroperoxyl radical ESR signal intensity. Quantifying the free chlorine concentration by the DPD method also revealed a linear relationship with the maximum absorbance at 354 nm, which in turn showed a linear relationship with the chloroperoxyl radical ESR signal intensity. These linear relationships suggest that the DPD method can quantify chloroperoxyl radicals, which this study considers to be the active species in ASC aqueous solution.

Evaluation of gaseous chlorine dioxide for the inactivation of Tulane virus on blueberries

To determine the effectiveness of gaseous chlorine dioxide (gClO2) against a human norovirus surrogate on produce, gClO2 was generated and applied to Tulane virus-coated blueberries in a 240 ml-treatment chamber. gClO2 was produced by an acidifying sodium chlorite solution. Initial assessments indicated that blueberries treated with gClO2 generated from ≤1 mg acidified sodium chlorite in the small chamber appeared unaffected while gClO2 generated from ≥10 mg of acidified sodium chlorite solution altered the appearance and quality of the blueberries. Treatments of inoculated blueberries with gClO2 generated from 0.1 mg sodium chlorite reduced the virus populations by >1 log after exposure for 30 to 330 min. For the 1 mg sodium chlorite treatments, the virus populations were reduced by >2.2 log after 15 min exposure and to non-detectable levels (>3.3 logs reductions) after 180 min exposure. Measured concentrations of gClO2 peaked in the treatment chamber at 0.9 μg/l after 10 min for 0.1 mg treatments and 600 μg/l after around 20 min for 1 mg treatment. Overall results indicate that gClO2 could be a feasible waterless intervention for blueberries and other produce.

Asidifiye Sodyum Klorit ve Asidifiye Sadyum Klorit İçeren Sosun Broyler Pirzolalarında Salmonella spp. Üzerine Etkisi

Bu çalışma, Salmonella spp. ile deneysel olarak kontamine edilen broiler pirzolalarının 4oC‘de muhafazasında bu patojen üzerine asidifiye sodyum klorit (ASK) ve ASK içeren sosun etkilerini incelemek amacıyla yapılmıştır. Örnekler 4oC‘de muhafaza edilerek 0., 2., 3., 5. ve 7. günlerde Salmonella spp. yönünden incelenmiştir. Salmonella spp. sayısı bakımından hem günler hem de gruplar arasındaki farkın önemli olduğu tespit edilmiştir. Salmonella spp. sayısında en fazla azalma 2,14 log kob/g ile 1800 ppm ASK çözeltisi uygulanan grupta, en az etki ise 0,08 log kob/g ile 1200 ppm ASK içeren sos uygulanan grupta belirlenmiştir. Kontrol ve sadece marinat uygulanan gruplarda ise patojen sayısında artış belirlenmiştir. Araştırma sonunda Salmonella spp. sayısı üzerine en yüksek antimikrobiyel etkinin 1200 ppm ve 1800 ppm ASK içeren çözeltilerde 2 dakika bekletildikten sonra muhafaza edilen broiler pirzolalarında olduğu tespit edilmiştir. Bu nedenle, asidifiye sodyum klorit çözeltisinin broiler pirzolalarında Salmonella spp. riskinin azaltılmasında etkili olacağı sonucuna varılmıştır.

Influence of alkaline hydrogen peroxide pre-hydrolysis on the isolation of microcrystalline cellulose from oil palm fronds

In the present study, microcrystalline cellulose (MCC) was isolated from oil palm fronds (OPF) using chemo-mechanical process. Wherein, alkaline hydrogen peroxide (AHP) was utilized to extract OPF fibre at different AHP concentrations. The OPF pulp fibre was then bleached with acidified sodium chlorite solution followed by the acid hydrolysis using hydrochloric acid. Several analytical methods were conducted to determine the influence of AHP concentration on thermal properties, morphological properties, microscopic and crystalline behaviour of isolated MCC. Results showed that the MCC extracted from OPF fibres had fibre diameters of 7.55–9.11nm. X-ray diffraction (XRD) analyses revealed that the obtained microcrystalline fibre had both celluloses I and cellulose II polymorphs structure, depending on the AHP concentrations. The Fourier transmission infrared (FTIR) analyses showed that the AHP pre-hydrolysis was successfully removed hemicelluloses and lignin from the OPF fibre. The crystallinity of the MCC was increased with the AHP concentrations. The degradation temperature of MCC was about 300°C. The finding of the present study showed that pre-treatment process potentially influenced the quality of the isolation of MCC from oil palm fronds.

Production of nanocellulose fibers from pinecone biomass: Evaluation and optimization of chemical and mechanical treatment conditions on mechanical properties of nanocellulose films

Nanocellulose fibers were produced from pinecone (Jack pine: Pinus banksiana Lamb) using chemical and mechanical treatments. The effects of pretreatment and mechanical grinding on the tensile strength and modulus of the cellulosic fiber sheets were studied to optimize the treatment conditions and grinding process used for the generation of high strength nanocellulose fibers. Pinecone and cellulose fibers were characterized for their chemical composition, morphology, crystallinity, and thermal properties using HPLC, FTIR, SEM, ESEM, XRD, and TGA to provide insight into the mechanism involved in the reactions. Cellulose suspensions that had different pretreatments were processed for different time periods in a Supermasscolloider to produce cellulose nanofibers. The cellulose fibers produced at the optimum chemical concentrations of 4wt% NaOH and 5wt% of acidified sodium chlorite solution contained approximately 89% of cellulose, 4% hemicellulose, and 6% lignin. About 67% of the prepared nanocellulose fibers showed a diameter range between 5 and 25nm. The tensile strength and modulus of the nano fiber films prepared at the optimized grinding condition were 273MPa and 17GPa, respectively. The high crystalline index (70%) and improved thermal stability of the nanofibers indicate their suitability for manufacturing bionanocomposites.

Enhanced bactericidal action of acidified sodium chlorite caused by the saturation of reactants.

Factors affecting the antibacterial action of acidified sodium chlorite (ASC), a widely used disinfectant, have not been determined. This study investigated the significant factors suggesting efficient production method to maximize bactericidal action of ASC. The effects of (i) preparation procedures (total three methods); (ii) initial concentrations of reactants: sodium chlorite (SC) and citric acid (CTA) (up to maximum solubility of each reactant) and (iii) final pH values (3·0 and 2·5) to the bactericidal action of ASC were investigated with a fixed final concentration of SC (10 ppm) using various foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium and Staphylococcus aureus). The antimicrobial compounds produced and the bactericidal effects depended on the preparation procedure and the initial concentrations of the reactants. The ASC prepared by premixing highly concentrated reactants (in particular > 40%) followed by dilution (dilution after reaction, DAR) was more effective in inactivating foodborne pathogens, and it produced higher antimicrobial compound (Cl(2) and ClO(2)) yields than the other procedures. A 5-min treatment with ASC, produced using the other procedures, resulted in a reduction of < 3·5 log CFU ml(-1) (Gram positive = 0·18-0·78; Gram negative = 0·03-3·49 log CFU ml(-1)), whereas ASC produced with the DAR procedure using the saturated reactants completely inactivated all of the test pathogens within 5 min without recovery (initial concentration = 6·94-7·08 log CFU ml(-1)). The ASC production with the DAR procedure using the saturated reactants maximizes both the antimicrobial compound yields and bactericidal effects of the ASC solutions. This study will contribute to increase the efficiency of ASC treatments for disinfections reducing the effective SC concentrations for industrial use.

Isolation and Characterization of Cellulose Nanofibers from Bambusa rigida

Alpha cellulose was extracted from Bambusa rigida fibers by carrying out Soxhlet extraction and bleaching and alkali treatments with acidified sodium chlorite solution and sodium hydrate solution. Then, cellulose nanofibers were isolated from α-cellulose with the combination of (33 wt%) sulfuric acid and ultrasonic treatment. The nano-sized fibers were successfully isolated, and the average diameters were about 10 to 30 nm. FTIR showed that a majority of the hemicelluloses and lignin were removed from the raw fiber and that the chemical constituents of α-cellulose and cellulose nanofibers were similar. XRD showed that the obtained nano-fibers presented a cellulose I structure, and thus the crystallinity of cellulose nanofibers was significantly increased. TGA showed that the thermal stability of the cellulose nanofibers was significantly improved. The relative crystallinity and thermal degradation temperature of the cellulose nanofibers reached 61.21% and 315.2 °C, respectively.

Use of chlorine dioxide gas for the postharvest control of Alternaria alternata and Stemphylium vesicarium on Roma tomatoes

Tomatoes and potatoes are the top produce affected in terms of value lost in the USA. Postharvest losses can occur anywhere from the time of harvest to the consumers' decision to eat or discard the food. These data support the importance of finding sustainable strategies to minimise food waste and preserve resources. This study evaluated the potential application of chlorine dioxide gas (ClO2 ) technology to control the postharvest spoilage of Roma tomatoes by Alternaria alternata and Stemphylium vesicarium. Data analysis showed that exposure time was a significant factor for fungal disease control (P < 0.05). After 3 min of treatment, mycelial growth was completely inhibited for A. alternata and S. vesicarium. Similar results were observed for conidial germination. The efficacy of ClO2 treatments was also studied under in vivo conditions. While untreated Roma tomatoes developed white moulds and black spots after 5 days of storage, produce decay was significantly (P < 0.05) delayed after 5 and 7 min treatments for S. vesicarium and A. alternata respectively. The use of ClO2 in the food industry is regulated by both the FDA and the EPA. Currently, only acidified sodium chlorite solutions are approved for the control of micro-organisms in water used to wash fruits and vegetables. No direct applications of ClO2 gas on fresh fruits and vegetables can be found in the regulations. More data are required by the two agencies to demonstrate that residues of ClO2 on produce surfaces are acceptable for human consumption.

Optimization of an Acidified Sodium Chlorite Solution for Reducing Pathogenic Bacteria and Maintaining Sensory Characteristics of Poultry Meat in Simulation Slaughter Process

Chicken breast meat was inoculated with Salmonella Typhimurium and Listeria monocytogenes and then washed with an acidified sodium chlorite (ASC) solution under conditions simulating those used in a commercial chicken processing plant. We evaluated the effects of ASC (concentrations ranging from 0 to 1 g/L, pH at 2.5, 3.5 and 6.5) on the reduction of microbial numbers, meat pH, color, total acceptability and chilled storage characteristics. The results showed that bacterial numbers were significantly reduced with increasing concentrations of ASC and with decreasing pH, reaching maximum reductions of 2.17 and 3.03 log cfu/g for S. Typhimurium and L. monocytogenes when washing with 1 g ASC/L at pH 2.5, respectively. Except for the treatment with 1 g ASC/L at pH 2.5, which resulted in a significant reduction of total acceptability of chicken meat, other treatments were all within an acceptable range. Considering the inactivation of bacteria and the changes in sensory characteristics of meat, we selected 0.8 g ASC/L at pH 2.5 as being optimal for our purpose.

A METHOD FOR ISOLATING CELLULOSE NANOFIBRILS FROM WOOD AND THEIR MORPHOLOGICAL CHARACTERISTICS

Toward exploiting cellulose nanofibrils with high aspect ratio and nano-order-unit interconnected web-like structure from poplar wood,a novel route was demonstrated,which combined the usual chemical procedures with high intensity ultrasonic treatment of the material in the water-swollen state. Firstly,lignin in the sample was removed using an acidified sodium chlorite solution. Secondly,the sample was treated with potassium hydroxide in order to leach hemicellulose. Lastly,the sample was processed with high intensity ultrasonication. Never-dried holocellulose,never-dried purified cellulose and wood cellulose nanofibrils (WCNF) were obtained,respectively. The changes of WCNF on the chemical composition,crystalline structure,crystallinity and morphologies during the preparation process were characterized by means of Fourier transform infrared spectroscopy (FTIR),X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the diameter distribution of WCNF was further calculated and analyzed by image analysis method. The results showed that the main composition of WCNF was cellulose with crystalline structure of Ⅰ type,and the crystallinity of WCNF was 65. 68% ,12. 33% higher than that of the raw material wood. The diameters,lengths and aspect ratio of WCNF were about 5 ～ 32 nm,longer than 10 μm and larger than 300,respectively. The nanofibrils of WCNF were also interconnected into unique web-like structure. The characteristics including high crystallinity,high aspect ratio,nano-order-scale,web-like entangled structure,and so on,indicate that WCNF is a perfect reinforcing and toughening material.

Efficacy of Chlorine and Acidified Sodium Chlorite on Microbial Population and Quality Changes of Spinach Leaves

Efficacy of washing with distilled water, chlorine solution, and acidified sodium chlorite (ASC) solution on populations of microorganisms on spinach leaves was evaluated. Washing with chlorine (100 mg/L) and ASC (sodium chlorite, 15 mg/L; citric acid, 200 mg/L) resulted in significant population reduction (1.1-1.9 log CFU/g) of aerobic microflora, coliform, and Escherichia coli O157:H7 (p < 0.05). There was no remarkable difference in decontamination efficacy between chlorine and ASC solution. In recent years, several sodium chlorite chemicals have been commercially available, and no difference in decontamination efficacy among the chemicals was observed when same concentration of sodium chlorite and citric acid were used. In addition, the reduction of E. coli O157:H7 population was influenced depending on the inoculation method and type of washing. It has been seen that dip-inoculated spinach leaves showed lower reduction than that of spot-inoculated spinach. After washing, populations of aerobic microflora, coliform, and E. coli O157:H7 were increased during storage at 10 degrees C, and washing condition before storage did not affect the subsequent increases in microbial population. Color of spinach leaves washed with ASC solution was not different from the color of those washed with water or chlorine solution, and washing with ASC solution was concluded to has no effect on appearance of spinach leaves.

Antimicrobial Effect of Acidified Sodium Chlorite (ASC) on Whole Croaker

The antimicrobial effect of acidified sodium chlorite (ASC) solution on whole croaker skin was evaluated. Whole croaker skin was treated with ASC (50, 100, 200, 400, and 600 ppm) and distilled water. After 10-minute exposure to 600 ppm ASC, 8% of Gram-negative bacteria survived on the whole croaker sample. Treatment with 50 ppm ASC eliminated all coliforms in the initial load. Immersion treatment with 600 ppm ASC resulted in 1.3 log CFU/㎠ greater kill of the initial mesophile loads of control (2.8 log CFU/㎠) than distilled water. Fifty ppm ASC solution produced a 1.6-log reduction of psychrotrophic bacteria. ASC treatment was an effective method for reducing naturally occurring microflora on whole croaker skin.

Acidified Sodium Chlorite Solution as an Antimicrobial Treatment for Rainbow Trout (Oncorhynchus mykiss) Fillets

Minimizing microbial growth and maintaining overall quality are priorities for intervention strategies that extend the shelf life of fresh, aquatic foods. Four treatments included a control (fresh fillets), water, 50 ppm of acidified sodium chlorite (ASC), and 1,000 ppm of ASC. Fillets were stored at 1 to 2°C for 0, 8, and 15 days. A significant (P < 0.05) interaction between treatment and storage time was observed for psychrotrophic counts. The increase in psychrotrophic counts with storage time was less for fillets treated with ASC, regardless of ASC concentration. Aerobic plate counts were not affected (P > 0.05) by intervention; however, a significant increase in counts was observed during storage (P < 0.05). Fillet pH, moisture, fat, thiobarbituric acid–reactive substances, fatty acid composition, color, cook yield, and shear force were not affected (P > 0.05) by intervention. Thiobarbituric acid–reactive substances decreased (P < 0.05) during storage. Percentages of individual fatty acids were constant, with the exception of C15 and C20:2; they decreased with storage to 15 days. Percent fat, L* (lightness) and b* (yellowness) values, and cook yield increased (P < 0.05) during storage. Fillet pH, moisture, a* (redness) value, and shear force did not change (P > 0.05) with storage to 15 days. Based on these data, 50 ppm of ASC performed equally as well as 1,000 ppm of ASC. The value of ASC is as a decontaminant; however, fillets in this study had low psychrotrophic counts pretreatment (2.3 log CFU/cm2) and posttreatment (2.03 log CFU/cm2), which did not demonstrate ASC's effectiveness as a decontaminant.

Effect of the sequential treatment of 1-methylcyclopropene and acidified sodium chlorite on microbial growth and quality of fresh-cut cilantro

This study investigated the effects of 1-methylcyclopropene and sanitizer (acidified sodium chlorite or sodium hypochlorite), treated alone or in combination, on microbial growth and quality of packaged fresh-cut cilantro ( Coriandrum sativum L.). Cilantro bunches were treated with 1.5 mg L −1 1-methylcyclopropene or air for 18 h at 10 °C. The samples were then cut and washed in tap water, 100 mg L −1 sodium hypochlorite, or 100 mg L −1 acidified sodium chlorite solution for 1 min. The washed cilantro leaves were centrifugally dried, packaged with 29.2 pmol s −1 m −2 Pa −1 oxygen transmission rate film, and stored at 5 °C for 14 d. Results indicated that 1-methylcyclopropene significantly ( P < 0.0001) delayed the decrease in O 2 and accumulation of CO 2 partial pressures in the headspace of sample packages. Acidified sodium chlorite application significantly reduced initial coliform/ Escherichia coli counts ( P < 0.001), and reduced decay rate at the end of storage ( P < 0.05). A combination treatment of 1-methylcyclopropene and acidified sodium chlorite, followed by acidified sodium chlorite treatment alone, maintained the lowest decay rates and the highest overall quality scores at the end of storage.

Efficacy of sodium chlorite as an inhibitor of enzymatic browning in apple slices

Sodium chlorite (SC) is an effective sanitizer for inhibiting microbial growth. This investigation was conducted to determine the efficacy of SC as a browning control agent for use on fresh-cut apple slices, applied alone, or in conjunction with organic acids. Additionally, the authors compared the efficacy of SC to that of acidified sodium chlorite (ASC) and to several other salts and examined the effect of pH and several different organic acids on efficacy of SC. The fresh-cut apple slices were dipped in treatment solutions for 1 min, then drained and placed in plastic containers at 20 °C for 24 h, and finally stored in polyethylene bags at 5 °C for 2 weeks. Color was measured periodically during storage. Lightness ( L) values for all treated and control samples measured at 4 h, 24 h, and 2 weeks of storage were compared to L value for untreated samples measured immediately after cutting. Percent decrease in L-values was calculated for each sample at each time interval. Apple slices treated in ASC or SC solution had a significantly smaller decrease in L value indicating less browning than those treated in citric acid or water control at 4 h ( P < 0.01), and with the exception of 1 g L −1 ASC and 0.1 g L −1 SC, all other ASC and SC treated slices still had significantly less browning than those for the water control ( P < 0.01) at 24 h. After 2 weeks of storage, only SC (0.5–1.0 g L −1), sodium bisulfite (0.5 g L −1) and calcium l-ascorbate (10 g L −1) continued to inhibit browning. Treatment with 0.5 g L −1 SC and pH adjusted in the range from 3.9 to 6.2 using citric acid (CA) reduced browning more effectively than 0.5 g L −1 SC without pH adjustment. Two organic acids, salicylic acid and cinnamic acid, when added to SC solution, were found to achieve even better inhibition of browning than CA at the same pH value.

Acidified sodium chlorite as an alternative to chlorine to control microbial growth on shredded carrots while maintaining quality

AbstractShredded carrots are particularly susceptible to microbial growth and quality deterioration as a result of a large cut surface area to mass ratio. Acidified sodium chlorite (ASC) in the concentration range 500–1200 µL L−1 has been shown to have stronger efficacy against pathogens and spoilage bacteria than chlorine and does not form carcinogenic products. However, ASC in this concentration range aggravates tissue damage. The objective of this study was to optimize ASC treatment parameters to balance antimicrobial activity with quality retention of shredded carrots. Shredded carrots were immersed for either 1 min in 100, 250 or 500 µL L−1 ASC solutions or 2 min in 200 µL L−1 chlorine or water (control). Treated samples were spin‐dried and packaged in polypropylene bags and stored at 5 °C for up to 21 days. Carrots were evaluated at 7‐day intervals for visual appearance, package atmosphere composition (O2 and CO2), product firmness, tissue electrolyte leakage and pH. The microbial growth, including total aerobic bacterial counts, total coliforms/Escherichia coli, yeast and mold counts and lactic acid bacterial counts on the products was also determined. Treatments with all concentrations of ASC reduced the aerobic bacterial counts, coliform/E. coli counts, yeast mold and counts and lactic acid bacterial populations by 1.2–2.0 log cfu g−1 when compared with the water‐washed and unwashed samples. During storage, unwashed samples had a sharp increase in lactic acid bacterial populations accompanied by a sharp decline in pH readings and rapid loss in firmness and tissue integrity; samples washed with 100 µL L−1 ASC maintained the best overall visual quality, accompanied by the retention of tissue integrity and firmness. Therefore, 100 µL L−1 was determined as the optimum concentration of ASC for maintaining overall quality and firmness, inhibiting microbial growth and prolonging the shelf‐life of shredded carrots. Copyright © 2006 Society of Chemical Industry

ACIDIFIED SODIUM CHLORITE, TRISODIUM PHOSPHATE AND POPULATIONS OFSALMONELLA TYPHIMURIUMANDSTAPHYLOCOCCUS AUREUSON CHICKEN-BREAST SKIN

The present study was designed to determine the individual and combined effects of acidified sodium chlorite (ASC) and trisodium phosphate (TSP) antimicrobial treatments. Chicken-skin samples inoculated with Salmonella typhimurium and Staphylococcus aureus were separately dipped into sterile tap water, 10% TSP, 0.1% ASC, 0.1% ASC followed by 10% TSP and 10% TSP followed by 0.1% ASC for 15 s at 25C ± 1. On day 0, reductions were 1.4-1.6 log for S. Typhimurium and 1.1-2.1 log for S. aureus, while they were 1.8-2.9 and 0.7-1.7 log, respectively, on day 5 of storage. Results indicated that treatment with ASC solution alone was more effective than treatment with ASC and TSP solutions combined in reducing S. aureus populations on chicken skin during the entire storage period. Similarly, treatment with TSP solution alone was more effective than treatment with ASC and TSP solutions combined in reducing S. typhimurium populations on chicken skin on days 1, 3 and 5 of storage.

Acidified Sodium Chlorite Treatment for Inhibition of Listeria monocytogenes Growth on the Surface of Cooked Roast Beef

The effects of acidified sodium chlorite (ASC) against Listeria monocytogenes on the surface of cooked roast beef were investigated. L. monocytogenes, strain V7, serotype 1/2a, was inoculated at numbers of 6.0 log CFU/g onto 5-g cubes of cooked regular or spicy roast beef. The samples were allowed to air dry for 1 h. The cooked roast beef samples were dipped into ASC or sprayed with ASC solutions of 250, 500, 750, or 1,000 ppm, then placed in bags with or without a vacuum and refrigerated at 4°C. L. monocytogenes counts were determined after 0, 7, 14, 21, and 28 days of storage by spread plating roast beef samples onto Oxford agar plates that were incubated at 37°C for 48 h. At day 28, the number of L. monocytogenes on the ≥500 ppm ASC-treated spicy roast beef samples had count reductions that were >4.0 log CFU/g, whereas the same concentrations of ASC-treated regular roast beef samples had approximately a 2.5 log CFU/g reduction in L. monocytogenes counts when compared with the untreated samples. No significant differences (P > 0.05) were observed in L. monocytogenes counts between the vacuum- or nonvacuum-packaged ASC-treated cooked roast beef samples. Sensory evaluation showed no significant differences (P > 0.05) between ASC-treated and untreated roast beef. ASC can be used as a processing aid in the form of a dip or spray treatment to control L. monocytogenes on the surface of cooked roast beef.

Effects of peroxyacetic acid, acidified sodium chlorite or lactic acid solutions on the microflora of chilled beef carcasses

The effects of solutions of 0.02% peroxyacetic acid, acidified 0.16% sodium chlorite, 2% lactic acid and 4% lactic acid on the natural flora of the distal surfaces of pieces of brisket, from chilled beef carcass quarters delivered from two slaughtering plants to a processing plant, were investigated. Peroxyacetic acid and acidified sodium chlorite solutions had little effect on the numbers of aerobes, coliforms or Escherichia coli on meat from one plant, and were less effective than 4% lactic acid for reducing the numbers of bacteria on meat from the other plant. With meat from both plants, treatment of meat with 4% lactic acid and holding for 5 or 60 min at 7±1 °C before sampling resulted in reductions of all three groups of bacteria by ≥1.5 log unit. Treatment with 2% lactic acid resulted in similar reductions when meat was sampled 5 min after the treatment, but reductions were about 1 log unit when meat was sampled 60 min after the treatment. Treatment of carcass quarters with 4% lactic acid resulted in reductions of bacterial numbers of ≥2 log units at distal surfaces, but ≤2 log units at medial surfaces. The findings indicate that the efficacies of antimicrobial solutions may be inconsistent when they are applied to chilled meat from different sources and to different types of meat surface, and that bacteria injured by application of an antimicrobial solution may recover during processing of meat at temperatures about 7 °C. However, 4% lactic acid may be generally useful as a decontaminant for chilled, raw meat.