Addition Of Nitrite Research Articles

Transcriptomic analysis of Staphylococcus xylosus in the presence of nitrate and nitrite in meat reveals its response to nitrosative stress.

Staphylococcus xylosus is one of the major starter cultures used for meat fermentation because of its crucial role in the reduction of nitrate to nitrite which contributes to color and flavor development. Despite longstanding use of these additives, their impact on the physiology of S. xylosus has not yet been explored. We present the first in situ global gene expression profile of S. xylosus in meat supplemented with nitrate and nitrite at the levels used in the meat industry. More than 600 genes of S. xylosus were differentially expressed at 24 or 72 h of incubation. They represent more than 20% of the total genes and let us to suppose that addition of nitrate and nitrite to meat leads to a global change in gene expression. This profile revealed that S. xylosus is subject to nitrosative stress caused by reactive nitrogen species (RNS) generated from nitrate and nitrite. To overcome this stress, S. xylosus has developed several oxidative stress resistance mechanisms, such as modulation of the expression of several genes involved in iron homeostasis and in antioxidant defense. Most of which belong to the Fur and PerR regulons, respectively. S. xylosus has also counteracted this stress by developing DNA and protein repair. Furthermore, it has adapted its metabolic response—carbon and nitrogen metabolism, energy production and cell wall biogenesis—to the alterations produced by nitrosative stress.

Stress Corrosion Cracking of an Austenitic Stainless Steel in Nitrite-Containing Chloride Solutions.

This article describes the susceptibility of 316L stainless steel to stress corrosion cracking (SCC) in a nitrite-containing chloride solution. Slow strain rate testing (SSRT) in 30 wt. % MgCl2 solution established SCC susceptibility, as evidenced by post-SSRT fractography. Addition of nitrite to the chloride solution, which is reported to have inhibitive influence on corrosion of stainless steels, was found to increase SCC susceptibility. The susceptibility was also found to increase with nitrite concentration. This behaviour is explained on the basis of the passivation and pitting characteristics of 316L steel in chloride solution.

Development of an Organic Acid Antifreeze Coolant

An organic acid antifreeze coolant was developed in this paper which consisted mainly of deionized water, organic acid, pyrrole compound, alkali and dye. Glycol, nitrite, chromate, inorganic phosphate and other harmful additives were not contained in this formulation. The coolant overcomes the disadvantages in environmental protection, heat transfer and cost of the current technology which uses the ethylene glycol as antifreeze. The coolant has good low temperature protection, thermal conductivity and corrosion protection performance. Further more, the coolant has the advantages of simple preparation, good storage stability and a promising prospects.

Nitrite survival and nitrous oxide production of denitrifying phosphorus removal sludges in long-term nitrite/nitrate-fed sequencing batch reactors

Nitrite-based phosphorus (P) removal could be useful for innovative biological P removal systems where energy and carbon savings are a priority. However, using nitrite for denitrification may cause nitrous oxide (N2O) accumulation and emissions. A denitrifying nitrite-fed P removal system (SBRNO2−) was successfully set up in a sequencing batch reactor (SBR) and was run for 210 days. The maximum pulse addition of nitrite to SBRNO2− was 11 mg NO2−-N/L in the bulk, and a total of 34 mg NO2−-N/L of nitrite was added over three additions. Fluorescent in situ hybridization results indicated that the P-accumulating organisms (PAOs) abundance was 75 ± 1.1% in SBRNO2−, approximately 13.6% higher than that in a parallel P removal SBR using nitrate (SBRNO3−). Type II Accumulibacter (PAOII) (unable to use nitrate as an electron acceptor) was the main PAOs species in SBRNO2−, contributing 72% to total PAOs. Compared with SBRNO3−, SBRNO2− biomass had enhanced nitrite/free nitrous acid (FNA) endurance, as demonstrated by its higher nitrite denitrification and P uptake rates. N2O accumulated temporarily in SBRNO2− after each pulse of nitrite. Peak N2O concentrations in the bulk for SBRNO2− were generally 6–11 times higher than that in SBRNO3−; these accumulations were rapidly denitrified to nitrogen gases. N2O concentration increased rapidly in nitrate-cultivated biomass when 5 or 10 mg NO2−-N/L per pulse was added. Whereas, N2O accumulation did not occur in nitrite-cultivated biomass until up to 30 mg NO2−-N/L per pulse was added. Long-term acclimation to nitrite and pulse addition of nitrite in SBRNO2− reduced the risk of nitrite accumulation, and mitigated N2O accumulation and emissions from denitrifying P removal by nitrite.

‘Interrupted’ diazotization of 3-aminoindoles and 3-aminopyrroles

‘Interrupted’ diazotization of 3-aminoindoles and 3-aminopyrroles, achieved by quenching with cold water immediately after the addition of nitrite, led, in good yields, to stable compounds whose structures were identified to be the diazonium species with nitrate as the counter ion, which show no saline character.

Mechanisms of nitrite addition for simultaneous sludge fermentation/nitrite removal (SFNR)

Simultaneous sludge fermentation and nitrite removal (SFNR) was investigated as a novel sludge/wastewater treatment process with high nitrogen concentrations. The results showed that introducing nitrite improved the primary sludge (PS) fermentation system by improving the chemical oxygen demand (COD) yields and the volatile suspend solid (VSS) reduction. At a nitrite dosage of 0.2 g g SS−1, the COD production was 1.02 g g VSS−1 and the VSS reduction was 63.4% within 7-day fermentation, while the COD production was only 0.17 g g VSS−1 and the VSS reduction was only 4.9% in the blank test. Nitrite contained in wastewater was removed through denitrification process in the SFNR system. The solubility of carbohydrate and protein was substantially enhanced, and their contents reached the peak once nitrite was consumed. In addition, the nutrient release and methane generation were inhibited in the SFNR system, which alleviated the environmental pollution. Unlike traditional fermentation systems, neither alkaline condition nor high free nitrite acid (FNA) concentration affected the PS fermentation in the SFNR system. Molecular weight distribution (MWD) and Live/Dead cell analysis indicated that the sludge disruption by nitrite and the consumption of soluble organic substances in sludge might play important roles in SFNR.

Integrating waste activated sludge (WAS) acidification with denitrification by adding nitrite (NO2−)

Adding nitrite (NO2−) to waste activated sludge (WAS) fermentation systems is an efficient approach to integrate fermentation with denitrification, and utilize volatile fatty acids (VFAs) to achieve a high nitrogen removal rate even at low C/N ratios. In this study, the effect of nitrite on the integrated WAS fermentation and denitrification (termed as WASFD) was investigated under acidic and alkaline conditions. The results indicated that adding nitrite achieved a most reduction of nitrite to N2 and improved the acidification of WAS with high VFAs production. Under acidic condition (pH = 5), the maximum VFAs produced with nitrite addition was 3.3 times that without nitrite addition. Higher concentration of free nitrous acid (FNA) at the pH of 5 increased WAS particulates, improved the hydrolysis of organic substrates, and finally promoted VFAs yields. Under alkaline condition (pH = 9), adding nitrite only increased the VFAs production by 1.5 times, indicating that acidic condition was preferable for acidification than alkaline condition.

Benzene Removal in Laboratory Scale Model Wetland under Different Electron Acceptor Conditions Treating Sulfate-Rich Wastewater

Constructed wetlands (CWs) are shown to be suitable for the treatment of water contaminated with benzene. However, due to the high sulfate concentration (around 850 mg/L) in influent, sulfate reduction will be stimulated in CWs. Subsequently, the toxicity of sulfide will be a catastrophe to the plants, and the treatment performance of CWs will be impaired. In this study, nitrite and nitrate were used as competitor with sulfate for electron acceptor to prevent the sulfate reduction. With the inflow benzene concentration ranged from 21.6-103 μg, and the accumulation of sulfide reached up to 39%, the removal efficiency of benzene decreased from 86% to 27%. However, with the addition of nitrite and nitrate, the sulfide accumulation was inhibited successfully, and the benzene removal efficiency recovered to 85%. In conclusion, both nitrite and nitrate can be an option for preventing sulfate reduction and sulfide toxicity in CWs treating sulfate-rich wastewater.

Alternatives for nitrate and nitrite in fermented meat products: potential contribution of the nitric oxide synthase activity of coagulase-negative staphylococci

Background Nitrosomyoglobin, which is the cured colour of fermented meat products, results from the interaction between muscle-based myoglobin and nitric oxide (NO) [1]. NO originates from the addition of nitrate and/or nitrite as curing agents to the meat batter. During fermentation, nitrate is reduced into NO-yielding nitrite by coagulasenegative staphylococci (CNS), present in the meat or added as starter culture [2]. However, health concerns related to the consumption of cured meats are leading to research for alternatives to generate the cured colour. A yet poorly explored pathway could potentially be based on the action of nitric oxide synthase (NOS), which produces NO from arginine. Bacterial NOS activity has only been scantily described, particularly its potential presence in meat-related bacteria and its dependency on environmental conditions. Based on preliminary attempts [3], and because up to now none of the sequenced Lactobacillus species contain a NOS homologue [4], this study focused on meat-related CNS.

Radiação gama e nitrito de sódio na composição química e textura de mortadelas

Um delineamento composto central rotacional (DCCR) foi conduzido para estudar os efeitos simultâneos da adição de nitrito (43,6; 150; 256,4; e 300 ppm) e de doses de radiação gama (2,9; 10; 17,1; e 20 kGy) nos atributos de textura e parâmetros físico-químicos de mortadelas. O pH, composição química e adesividade das mortadelas não foram afetados por nenhuma das variáveis estudadas, enquanto a dureza e a mastigabilidade foram influenciados pela aplicação da radiação gama. Modelos de regressão significativos (P<0,05) foram estabelecidos para a atividade de água, coesividade e flexibilidade das amostras. Estes modelos indicam que os efeitos da irradiação gama sobre estes parâmetros é dependente do nível de nitrito adicionado, sendo o comportamento diferente para amostras com níveis de adição menores que 150 ppm de nitrito daquelas com níveis de adição maiores.

Arsenite Oxidation Initiated by the UV Photolysis of Nitrite and Nitrate

This study demonstrates that the production of reactive oxidizing species (e.g., hydroxyl radical (•OH)) during the photolysis of nitrite (NO2(-)) or nitrate (NO3(-)) leads to the oxidative conversion of arsenite (As(III)) to arsenate (As(V)). While the direct UV photolytic oxidation of As(III) was absent, nitrite (20 or 200 μM) addition markedly accelerated the oxidation of As(III) under UV irradiation (λ > 295 nm), which implies a role of NO2(-) as a photosensitizer for As(III) oxidation. Nitrate-mediated photooxidation of As(III) revealed an initial lag phase during which NO3(-) is converted into NO2(-). UV-Photosensitized oxidation of As(III) was kinetically enhanced under acidic pH condition where nitrous acid (HNO2) with a high quantum yield for •OH production is a predominant form of nitrite. On the other hand, alkaline pH that favors the photoinduced transformation of NO3(-) to NO2(-) significantly facilitated the catalytic reduction/oxidation cycling, which enabled the complete oxidation of As(III) at the condition of [As(III)]/[NO2(-)] ≫ 1 and markedly accelerated NO3(-)-sensitized oxidation of As(III). The presence of O2 and N2O as electron scavengers enhanced the photochemical dissociation of NO2(-) via intermolecular electron transfer, initiating the oxidative As(III) conversion route probably involving NO2• and superoxide radical anion (O2•(-)) as alternative oxidants. The outdoor experiment demonstrated the capability of NO2(-) for the photosensitized production of oxidizing species and the subsequent oxidation of As(III) into As(V) under solar irradiation.

A Flow Cytometric Analysis of the Inhibition of Platelet Reactivity Due to Nitrite Reduction by Deoxygenated Erythrocytes

Nitric oxide (NO), a small gas molecule, has long been known to be a potent inhibitor of platelet function but the physiological and pathological implications of platelet inhibition by NO have not been well clarified. We recently showed that the addition of nitrite to platelet-rich plasma in the presence of erythrocytes could inhibit platelet aggregation and this inhibitory effect of nitrite + erythrocytes was enhanced by deoxygenation of erythrocytes as measured by P-selectin expression and cGMP production. In order to study the nitrite effect on platelets at different oxygen levels, we used the flow cytometric assays to detect platelet membrane surface markers upon activation. The P-selectin and activated gpIIb/IIIa expression on platelet membranes in response to ADP, collagen and thrombin stimulation was measured at various hematocrit and oxygen levels. Nitrite (0.1 to 1.0 μM) significantly decreased the percentage of these surface markers on the platelet membrane at the hematocrit values above 23% and oxygen levels lower than 49 mmHg. The inhibitory effect of nitrite was augmented by increasing hematocrit values and decreasing oxygen saturation. C-PTIO (an NO scavenger) prevented the platelet inhibition by nitrite + erythrocytes whereas the inhibitors of NO synthase and xanthine oxidoreductase had no effect. These results support the proposal that circulating nitrite decreases platelet reactivity in the presence of partially deoxygenated erythrocytes through its reduction to NO, which may also explain certain differences between arterial and venous thrombosis and support directly the role of deoxyhemoglobin in this process. We believe that our flow cytometric assays offer a possibility to identify the individual molecular process involved in these effects.

Oxidative and Nitrosative Stress Induced in Myofibrillar Proteins by a Hydroxyl-Radical-Generating System: Impact of Nitrite and Ascorbate

Understanding the chemistry behind the redox properties of nitrite and ascorbate is essential to identify the impact of curing agents on food quality and optimize the formulation of cured meat products. This study was designed to gain insight into the interactions between curing agents and myofibrillar proteins (MPs) during in vitro oxidation by a hydroxyl-radical-generating system. MPs (4 mg/mL) were oxidized for 4 days at 37 °C under constant stirring with 25 μM iron(III) and 2.5 mM hydrogen peroxide. Dependent upon the addition of nitrite (0, 75, and 150 mg/L) and ascorbate (0, 250, and 500 mg/L), nine different reaction units were prepared in triplicate (n = 3) according to a total factorial design. Upon completion of the oxidation assay, samples were analyzed for the concentration of tryptophan (TRP), α-aminoadipic semialdehyde (AAS), Schiff bases (SBs), and 3-nitrotyrosine (3NT). Ascorbate at 250 mg/L significantly inhibited the depletion of TRP (∼20% inhibition) and the formation of AAS and SBs (>90% inhibition) in MP suspensions. Nitrite, alone, had a negligible effect on protein oxidation but induced the formation of a specific marker of nitrosative stress, namely, 3NT. Ascorbate was also efficient at inhibiting the formation of 3NT by a dose-dependent anti-nitrosative effect and enabled the antioxidant action of nitrite.

Influence of Compound Sensitizers on Compression Resistance of Deep Water of Emulsion Explosives

compound sensitizing agent is an important component of the emulsion explosive, by using reusable experiment device to simulate the deep charging environment, study compound sensitizing agent on the properties of emulsion explosive deep water pressure resistance. Experimental results show that the mixed sensitizing, the deep water pressure resistance of three kinds of emulsion explosive performance award to him a bad order: glass microspheres + perlite + sodium nitrite sensitization, glass microspheres + perlite and sensitizing sodium nitrite sensitization. Compound containing glass microspheres sensitizer, the measurement of explosive performance closer to sensitization performance when only glass microspheres, perlite, the addition of sodium nitrite on the explosive performance contribution is small. Sodium nitrite and perlite mixed sensitizing, explosive detonation "hot spots", first class formation is chemical sensitization is given priority to, only a minority of perlite as "hot spots", the measurement of explosive performance closer to use sodium nitrite sensitization performance.

Effect of reducing and replacing pork fat on the physicochemical, instrumental and sensory characteristics throughout storage time of small caliber non-acid fermented sausages with reduced sodium content

The effect of pork fat reduction (from 44% to 20% final fat content) and its partial substitution by sunflower oil (3% addition) on the physicochemical, instrumental and sensory properties throughout storage time of small caliber non-acid fermented sausages (fuet type) with reduced sodium content (with partial substitution of NaCl by KCl and K-lactate) and without direct addition of nitrate and nitrite (natural nitrate source used instead) was studied. Results showed that sausages with reduced fat (10% initial fat content) and with acceptable sensory characteristics can be obtained by adding to the shoulder lean (8% fat content) during the grinding, either 3.3% backfat (3% fat content) or 3% sunflower oil, both previously finely comminuted with lean. Furthermore, sunflower oil showed to be suitable for partial pork backfat substitution in very lean fermented sausages, conferring desirable sensory properties similar to those of sausages with standard fat content. The sensory quality of the sausages was maintained after three-month cold storage in modified atmosphere.

Quantitative determination of nitric oxide production in haemocytes: Nitrite reduction activity as a potential pathway of NO formation in haemolymph of Galleria mellonella larvae

The generation of nitric oxide by Galleria mellonella larvae haemocytes has been investigated. For this purpose, a fluorescent method, specific for detection of NO, has been developed. The method is based on the application of fluorescence probe DAF-FM diacetate and nitronyl nitroxyl radical, NNR, which accelerates the NO-dependent formation of fluorescence product, DAF-FM triazole. The key feature of the method is the registration and analysis of differential kinetics, namely, the difference of kinetics obtained in samples with NNR and without NNR. This approach allows us to exclude any other kinetic processes not related to triazole formation. The differential kinetics were calibrated versus NO generation rate and the resulting low limit of method sensitivity was obtained as about 0.4–0.5nM/min. The generation of nitric oxide by the haemocytes of insects treated with LPS in vivo has been detected at a rate of 0.5–0.7nM/min. However, the production of NO in haemocyte suspensions treated with both the substrate, l-arginine, and the inhibitor, l-NAME, of NOS, has not been detected within method sensitivity. These data provide only the upper level of NO generation by haemocytes but cannot be used to draw definite conclusions about NOS as a source of NO. Meanwhile, it is known, that NO can be formed by NOS independent mechanism. Indeed, we have observed a significant increase in NO generation in the samples of haemocytes intracellularly loaded with nitrite. Moreover, adding nitrite to lysed haemocytes results in the higher NO generation rate. After addition of 500μM nitrite, the rates of NO generation in the samples are determined to be 2 and 20–30nM/min, respectively. The nitrite/nitrate content of haemocytes and lymph were found to be 5 and 50μM, respectively. The detected nitrite reduction activity of haemocytes allowed us to estimate the generation rate of nitric oxide as 0.05–0.5nM/min from endogenous nitrite. It is thus assumed that the observed nitrite reduction activity in haemocytes is dominant in the increased NO production during immune response of the G. mellonella larvae.

Preventive and therapeutic effects of nitrite supplementation in experimental inflammatory bowel disease

BackgroundInorganic nitrate and nitrite have emerged as alternative substrates for nitric oxide (NO) generation in the gastrointestinal tract, and have shown to be protective against drug-induced gastric injury. The aim of this study was to investigate the preventive and therapeutic effects of nitrate and nitrite in a model of experimental colitis. MethodsColitis was induced in mice by administrating dextran sulfate sodium (DSS) with concurrent administration of nitrite (1mM) or nitrate (10mM) in the drinking water for 7 days. A therapeutic approach was also investigated by initiating nitrite treatment 3 days after DSS-induced colitis. Clinical and inflammatory markers were assessed and the colonic mucus thickness was measured in vivo. The effect of nitrite on wound healing was evaluated using colon epithelial cells. ResultsConcurrent administration of DSS and nitrite (1mM) alleviated inflammation as determined by reduced disease activity index score (DAI) and increased colon length, while nitrate (10mM) only reduced the DAI-score. Nitrite also displayed therapeutic effects by ameliorating established colonic inflammation with reduced colonic expression of iNOS and improving histopathology. DSS-induced decrease in colonic mucus thickness was completely prevented by nitrite administration. In addition, goblet cell abundance was lower by DSS treatment, but was increased by addition of nitrite. Further studies using colon epithelial cells revealed an NO-dependent improvement in wound healing with nitrite administration. ConclusionNitrite exerts both preventive and therapeutic effects in colonic inflammation. The protective effects involve preservation of an intact adherent mucus layer and regulation of epithelial cell restitution.

Impact of Flue Gas Contaminants on Monoethanolamine Thermal Degradation

The buildup of flue gas contaminants in amine-based postcombustion CO2 capture processes is an important concern due to its potential impact on solvent degradation and reclaiming. In this research, in order to explore the impact of flue gas contaminants on solvent thermal degradation, sodium nitrite, fly ash, sodium sulfate, and sodium thiosulfate were each added into carbon-loaded 5.0 M monoethanolamine (MEA) solution and the solutions were exposed to high-temperature degradation conditions. MEA degrades significantly more in the presence of nitrite (5000 ppm) than MEA alone at the same amine mole concentration. The MEA degradation activation energy of MEA–nitrite solution is calculated and found to be approximately one-seventh of that of MEA solution without nitrite. Addition of nitrite not only enhanced generation of several MEA thermal degradation products but also induced formation of diethanolamine (DEA) and N-(2-hydroxyethyl)piperazin-3-one (HEPO), which have been known to form during MEA oxidative...

Effect of the Addition of Schisandra chinensis Powder on the Physico-chemical Characteristics of Sausage.

The individual and interactive effects of Schisandra chinensis powder (SCP) and sodium nitrite additions on color, pH, water holding capacity, residual nitrite, 2-thiobarbituric acid reactive substances (TBARS), volatile basic nitrogen, texture properties, fatty acids, amino acids and sensory evaluation of cooked pork sausages were investigated after 20 d of storage at 4°C. The powders (0, 0.5 and 1.0%) were added to sausages either alone or in combination with nitrite (0 and 100 ppm). SCP added-sausages showed lower L* (lightness) and W (whiteness) values, and higher b* (yellowness) values than sausage containing no nitrite, and exhibited the highest a* values at a 0.5% addition (p<0.05). Residual nitrite and TBARS values were found to be significantly reduced as the addition levels of SCP increased (p<0.05). As the addition of SCP increased, the sausage showed gradually decreased brittleness, cohesiveness, springiness, gumminess and chewiness, while adhesiveness increased. Polyunsaturated fatty acid, n-6 and n-6/n-3 fatty acid ratio concentrations were significantly higher in sausages containing SCP (p<0.05). The addition of SCP to sausage significantly (p<0.05) increased the ammonia content (by 0.5% SCP) and aromatic amino acid concentrations (by 1.0% SCP) (p<0.05). Inclusion of SCP in sausage meat resulted in a significant deterioration in quality characteristics of flavor, springiness, juiciness and overall acceptability (p<0.05). As expected, the observed changes in a*, W, pH, shear force, texture property, TBARS, fatty acid, amino acid and sensory score of sausages, depended on the rate of addition of nitrite (p<0.05). These results suggest that SCP addition is not an effective way of improving the sensory evaluation of sausages, but may beneficially affect TBARS, nitrite scavenging activity, fatty acid and amino acid content in pork sausages.

Cyclic voltammetry evaluation of inhibitors for localised corrosion in alkaline solutions

The paper focuses on chloride corrosion of steel rebar in alkaline solutions. The effect of chloride content on corrosion initiation was assessed through cyclic voltammetry (CV) tests at pH values between 12.6 and 13.8. The potential value E1,1st was derived by CV tests to define the pitting initiation condition. The effect of inhibitor addition on the critical chloride content was also assessed. The performances of two innovative organic-acid-based inhibitors were compared to that of sodium nitrite, which is the most used for chloride corrosion prevention in concrete; the parameter f* was proposed for comparison purposes; this parameter defines the efficiency of the substance compared to alkalinity to prevent pitting initiation.The results confirm the role of the chloride-alkalinity ratio in corrosion initiation; when the value of the ratio exceeds 0.6, the probability increases, confirming the literature data. The addition of nitrites causes an increase in the critical chloride threshold, as expected. The efficiency of sodium nitrite is similar to the effect of alkalinity; the value of the coefficient f* is equal to 0.84. Sodium aspartate exhibited the highest effect at pH values approaching 13.7; lower pH values resulted in lower efficiencies, nearly reaching zero at pH 12.6. Sodium lactate showed the lowest efficiency (f*=0.01).