SEARCH · PubMed Health

Results for “Nitrites”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources

PubMed2003

Effect of sodium nitrite and ascorbic acid on the growth and acid production of Streptococcus mutans.

UNLABELLED: Nitrite at acid pH has been shown to be antibacterial particularly against the highly cariogenic species Streptococcus mutans. Nitrite might yield nitrosamines in vivo but ascorbic acid (vitamin C) could counteract these potential ill effects. The aim of this study is to determine whether ascorbic acid would interfere with the ability of sodium nitrite to suppress growth and acid production of S. mutans, NCTC 10449(T) and NCTC 10832. Strains were grown in Fastidious Anaerobe Broth before exposure to 200 mM nitrite in the presence of various concentrations of ascorbic acid (0.0, 5.7, 11.4, 17.0, 22.7, 28.4, 56.8, 85.2 mM). End pH was measured after 24 h exposure and cultures were serially diluted for viable counts. Statistical significance of differences in end pH values, each from 10 experiments, was determined using the Mann-Whitney U-Test. At all concentrations of ascorbic acid plus 200 mM nitrite plus S. mutans the pH was higher than with controls lacking ascorbic acid and/or nitrite (p>/=0.001). S. mutans was viable (between 4.5 x 10 (8) and 7.9 x 10 (9) cfuml (-1)) after growth in the presence of ascorbic acid at all concentrations without nitrite, whereas it was not detected when 200 mM nitrite was also present. CONCLUSIONS: ascorbic acid does not prevent the action of nitrite against S. mutans. Therefore ascorbic acid could be used in conjunction with nitrite to help counteract potential ill effects for humans.

Acids↗

PubMed2001

Optimal operational factors for nitrite accumulation in batch reactors.

The environmental factors that affected the accumulation of nitrite in nitrifying reactors were investigated using a mixed culture. A batch reactor with 50 mg-N/l of ammonia was used. The pH, temperature and dissolved oxygen concentration were varied. The concentration of unionized free ammonia also changed with the oxidation of ammonia and the variation of pH and temperature. The accumulation of nitrite was affected sensitively by pH and temperature. A higher nitrite concentration was observed at pH 8-9 or temperature around 30 degrees C. The dissolved oxygen also affected, giving the highest nitrite accumulation at around 1.5 mg/l. These were the favored conditions for nitrite production. The free ammonia concentration influenced the nitrite accumulation also, by inhibiting nitrite oxidation. The inhibition became apparent at a concentration of approximately 4 mg/l or above, but insignificant at below 1 mg/l. Thus, simultaneously high free ammonia concentration and maximum specific ammonia-oxidation rate (above 15 x 10(-3) mg-N/mg-VSS x h) were needed for a significant nitrite accumulation. When the two conditions were met, then the highest accumulation was observed when the ratio of the maximum specific oxidation rate of ammonia to the maximum specific oxidation rate of nitrite (ka/kn) was highest. Under the optimal operating conditions of pH 8, 30 degrees C and 1.5 mg/l of dissolved oxygen, as much as 77% of the removed ammonia accumulated in nitrite.

Algorithms↗

PubMed2002

Nitrite reduction by a mixed culture under conditions relevant to shortcut biological nitrogen removal.

Dissimilative reduction of nitrite by nitrite-acclimated cells was investigated in a batch reactor under various environmental conditions that can be encountered in shortcut biological nitrogen removal (SBNR: ammonia to nitrite and nitrite to nitrogen gas). The maximum specific nitrite reduction rate was as much as 4.3 times faster than the rate of nitrate reduction when individually tested, but the reaction was inhibited in the presence of nitrate when the initial nitrate concentration was greater than approximately 25 mg-N/1 or the initial NO3(-)N/NO2(-)-N ratio was larger than 0.5. Nitrite reduction was also inhibited by nitrite itself when the concentration was higher than that to which the cells had been acclimated. Therefore, it was desirable to avoid excessively high nitrite and nitrate concentrations in a denitrification reactor. Nitrite reduction, however, was not affected by an alkaline pH (in the range of 7-9) or a high concentration of FA (in the range of 16-39 mg/l), which can be common in SBNR processes. The chemical oxygen demand (COD) requirement for nitrite reduction was approximately 22-38% lower than that for nitrate reduction, demonstrating that the SBNR process can be economical. The specific consumption, measured as the ratio of COD consumed to nitrogen removed, was affected by the availability of COD and the physiological state of the cells. The ratio increased when the cells grew rapidly and were storing carbon and electrons.

Ammonia↗

PubMed1996

Purification and characterization of assimilatory nitrite reductase from Candida utilis.

Nitrate assimilation in many plants, algae, yeasts and bacteria is mediated by two enzymes, nitrate reductase (EC 1.6.6.2) and nitrite reductase (EC 1.7.7.1). They catalyse the stepwise reduction of nitrate to nitrite and nitrite to ammonia respectively. The nitrite reductase from an industrially important yeast, Candida utilis, has been purified to homogeneity. Purified nitrite reductase is a heterodimer and the molecular masses of the two subunits are 58 and 66 kDa. The native enzyme exhibits a molecular mass of 126 kDa as analysed by gel filtration. The identify of the two subunits of nitrite reductase was confirmed by immunoblotting using antibody for Cucurbita pepo leaf nitrite reductase. The presence of two different sized transcripts coding for the two subunits was confirmed by (a) in vitro translation of mRNA from nitrate-induced C. utilis followed by immunoprecipitation of the in vitro translated products with heterologous nitrite reductase antibody and (b) Northern-blot analysis. The 66 kDa subunit is acidic in nature which is probably due to its phosphorylated status. The enzyme is stable over a range of temperatures. Both subunits can catalyse nitrite reduction, and the reconstituted enzyme, at a higher protein concentration, shows an activity similar to that of the purified enzyme. Each of these subunits has been shown to contain a few unique peptides in addition to a large number of common peptides. Reduced Methyl Viologen has been found to be as effective an electron donor as NADPH in the catalytic process, a phenomenon not commonly seen for nitrite reductases from other systems.

Candida↗

PubMed2001

The bactericidal effect and chemical reactions of acidified nitrite under conditions simulating the stomach.

AIMS: To examine the hypothesis of non-immune defence mechanisms based on nitrite. METHODS AND RESULTS: The acidified media (nutrient broth or citrate-phosphate buffer) under aerobic conditions with additions of physiological levels of nitrite, L-ascorbic acid, iodide and thiocyanate were used to simulate gastric juice. The bactericidal effects of acidified nitrite on Escherichia coli and lactobacilli were investigated using bacterial plate counts. Conversion of acidified nitrite to nitric oxide, nitrogen dioxide and nitrate was also studied. Nitrite significantly increased the bactericidal effects on E. coli and lactobacilli. The bactericidal effects were enhanced by thiocyanate but not by L-ascorbic acid and iodide. L-Ascorbic acid and thiocyanate, but not iodide, enhanced the decomposition of acidified nitrite in nutrient broth. Acidified nitrite was converted to both nitric oxide and nitrate, but a portion of the acidified nitrite in nutrient broth may have been converted to other unidentified nitrogen compounds. Nitrogen dioxide was not detected in any of the samples. CONCLUSION: The bactericidal effects of nitrite appeared to be primarily related to nitrous acid, and possibly to other unidentified nitrogenous metabolites, but not to nitric oxide and nitrogen dioxide. SIGNIFICANCE AND IMPACT OF THE STUDY: The potential role of nitrite as an antimicrobial substance in the stomach may be of some importance in the ecology of the gastrointestinal tract and in host physiology.

Anti-Bacterial Agents↗

PubMed2000

A NapC/NirT-type cytochrome c (NrfH) is the mediator between the quinone pool and the cytochrome c nitrite reductase of Wolinella succinogenes.

Wolinella succinogenes can grow by anaerobic respiration with nitrate or nitrite using formate as electron donor. Two forms of nitrite reductase were isolated from the membrane fraction of W. succinogenes. One form consisted of a 58 kDa polypeptide (NrfA) that was identical to the periplasmic nitrite reductase. The other form consisted of NrfA and a 22 kDa polypeptide (NrfH). Both forms catalysed nitrite reduction by reduced benzyl viologen, but only the dimeric form catalysed nitrite reduction by dimethylnaphthoquinol. Liposomes containing heterodimeric nitrite reductase, formate dehydrogenase and menaquinone catalysed the electron transport from formate to nitrite; this was coupled to the generation of an electrochemical proton potential (positive outside) across the liposomal membrane. It is concluded that the electron transfer from menaquinol to the catalytic subunit (NrfA) of W. succinogenes nitrite reductase is mediated by NrfH. The structural genes nrfA and nrfH were identified in an apparent operon (nrfHAIJ) with two additional genes. The gene nrfA encodes the precursor of NrfA carrying an N-terminal signal peptide (22 residues). NrfA (485 residues) is predicted to be a hydrophilic protein that is similar to the NrfA proteins of Sulfurospirillum deleyianum and of Escherichia coli. NrfH (177 residues) is predicted to be a membrane-bound tetrahaem cytochrome c belonging to the NapC/NirT family. The products of nrfI and nrfJ resemble proteins involved in cytochrome c biogenesis. The C-terminal third of NrfI (902 amino acid residues) is similar to CcsA proteins from Gram-positive bacteria, cyanobacteria and chloroplasts. The residual N-terminal part of NrfI resembles Ccs1 proteins. The deduced NrfJ protein resembles the thioredoxin-like proteins (ResA) of Helicobacter pylori and of Bacillus subtilis, but lacks the common motif CxxC of ResA. The properties of three deletion mutants of W. succinogenes (DeltanrfJ, DeltanrfIJ and DeltanrfAIJ) were studied. Mutants DeltanrfAIJ and DeltanrfIJ did not grow with nitrite as terminal electron acceptor or with nitrate in the absence of NH4+ and lacked nitrite reductase activity, whereas mutant DeltanrfJ showed wild-type properties. The NrfA protein formed by mutant DeltanrfIJ seemed to lack part of the haem C, suggesting that NrfI is involved in NrfA maturation.

Amino Acid Sequence↗

PubMed1996

Dietary intakes of nitrate, nitrite and NDMA in the Finnish Mobile Clinic Health Examination Survey.

Concern about potential health hazards of nitrate, nitrite and N-nitroso compounds necessitates calculations of exposures to these compounds and their distribution in normal populations. This study describes dietary intake of nitrate (NO3-), nitrite (NO2-) and N-nitrosodimethylamine (NDMA) among 5304 adult men and 4750 women, who participated in the Finnish Mobile Clinic Health Examination Survey in 1967-72. Food consumption data for each individual over the preceding year were collected by a dietary history interview. Intakes of nitrate, nitrite and NDMA from vegetables, fruits, cheese, meat and fish products were calculated using available values mainly derived from Finland and other countries in northern Europe. Nitrate and nitrite from drinking water were not included in the study. Mean daily dietary intake of nitrate was 77 mg, of nitrite 5.3 mg, and of NDMA 0.05 microgram respectively. Intake of NDMA from beer, estimated in a part of the study population, was 0.07 microgram per day. More than 90% of dietary nitrate was derived from vegetables, including potatoes. Nitrite was mainly provided by cured meat products. Cured meat products and smoked and salted fish were important food sources of NDMA. The total daily intake of nitrate was similar in men and women, whereas intakes of nitrite and NDMA were higher in men than in women. The diet of farmers was characterized by lower amounts of nitrate, nitrite and NDMA, whereas white collar workers and those employed in industry had higher intakes. Current smokers were exposed to higher dietary intakes of nitrate, nitrite and NDMA than non-smokers. Intakes of dietary nitrate, nitrite and NDMA estimated on an individual level are suggested to be useful in evaluating the health effects of these compounds in epidemiological studies.

Adolescent↗

PubMed2004

Nitrite generates an oxidant stress and increases nitric oxide in EA.hy926 endothelial cells.

Nitrite is a breakdown product of nitric oxide that in turn is oxidized to nitrate in cells. In this work, we investigated whether reactive oxidant species mightbe generated during nitrite metabolism in cultured EA.hy926 endothelial cells. Nitrite was taken up by the cells in a time- and concentration-dependent manner and oxidized to nitrate, which accumulated in cells to concentrations almost 10-fold those of nitrite. Conversion of low millimolar concentrations of nitrite to nitrate was associated with increased oxidant stress in the cells. This manifested as increased oxidation of dihydrofluorescein in tandem with depletion of both GSH and ascorbate. Further, loading cells with ascorbate or treatment with desferrioxamine prevented nitrite-induced dihydrofluorescein oxidation. Nitrite within cells also increased the fluorescence of 4-amino-5-methylamino-2',7'-difluorofluorescein and inhibited the activity of cellular glyceraldehyde 3-phosphate dehydrogenase, which are markers of intracellular nitrosation reactions. Intracellular ascorbate partially prevented both of these effects of nitrite. Although ascorbate can reduce nitrite to nitric oxide at low pH, in endothelial cells loaded with ascorbate, its predominant effect at high nitrite concentrations is to prevent potentially damaging nitrosation reactions.

Cell Line↗

PubMed2004

Dietary nitrites and nitrates, nitrosatable drugs, and neural tube defects.

BACKGROUND: Amine-containing (nitrosatable) drugs can react with nitrite to form N-nitroso compounds, some of which are teratogenic. Data are lacking on whether dietary intake of nitrates and nitrites modifies the association between maternal nitrosatable drug exposure and neural tube defects (NTDs) in offspring. METHODS: We examined nitrosatable drug exposure and NTD-affected pregnancies in relation to dietary nitrite and total nitrite intake in a case-control study of Mexican American women. We interviewed 184 women with NTD-affected pregnancies and 225 women with normal live births, including questions on periconceptional drug exposures and dietary intake. For 110 study participants, nitrate was also measured in the usual source of drinking water. RESULTS: Women who reported taking drugs classified as nitrosatable were 2.7 times more likely to have an NTD-affected pregnancy than women without this exposure (95% confidence interval [CI] = 1.4-5.3). The effect of nitrosatable drugs was observed only in women with higher intakes of dietary nitrite and total nitrite (dietary nitrite + 5% dietary nitrate). Women within the highest tertile (greater than 10.5 mg/day) of total nitrite were 7.5 times more likely to have an NTD-affected pregnancy if they took nitrosatable drugs (95% CI = 1.8-45.4). The association between nitrosatable drug exposure and NTDs was also stronger in women whose water nitrate levels were higher. CONCLUSIONS: Findings suggest that effects of nitrosatable drug exposure on risk for neural tube defects in offspring could depend on the amounts of dietary nitrite and total nitrite intake.

Adolescent↗

PubMed1988

Identification of rumen bacteria that anaerobically degrade nitrite.

Fifty-one pure strains of rumen bacteria, representing 15 genera, were tested for their ability to metabolize nitrite. Twenty-five of the strains, belonging to eight genera, were capable of growth and nitrite metabolism in nitrite-containing medium sterilized by autoclaving. An additional 10 strains showed growth and nitrite metabolism in medium that was autoclaved before the addition of filter-sterilized nitrite. Nitrite metabolism was not observed in the remaining 16 strains, and these were also incapable of growth in the presence of nitrite. Ammonia was produced during nitrite reduction by Megasphaera elsdenii J1. In agreement with previous studies, abiotic losses of nitrite were observed during autoclaving and storage of media, but losses of nitrite due to bacterial metabolism were much greater.

Ammonia↗

PubMed2004

Nitrite-derived nitric oxide formation following ischemia-reperfusion injury in kidney.

Nitric oxide (NO) is synthesized from l-arginine by nitric oxide synthase (NOS), and nitrite and nitrate are believed to be waste forms of NO. We previously reported an enzyme-independent pathway of NO generation from nitrite in acidic conditions. In this study, we show nitrite-derived NO formation in renal ischemia-reperfusion injury using electron paramagnetic resonance (EPR) spectroscopy. In this experiment, we utilized a stable isotope of [(15)N]nitrite as a source of nitrite to distinguish l-arginine-derived NO from [(15)N]nitrite-derived (15)NO. Intravenous infusion of a stable isotope of [(15)N]nitrite ((15)NO(2)(-)) facilitated the formation of Hb(15)NO during renal ischemia, which demonstrated that the origin of NO was nitrite. The EPR signal of Hb(15)NO in kidney appeared after 40 min of renal ischemia, and renal reperfusion decreased the Hb(15)NO level in the kidney and increased it in blood by contrast. In addition, the amount of HbNO was nitrite concentration dependent, and this formation was NOS independent. Our findings suggest that nitrite can be an alternative source of NO in ischemic kidney and that it binds with hemoglobin and then is spread by the circulation after reperfusion.

Animals↗

PubMed1998

Salivary nitrate, nitrite and nitrate reductase activity in relation to risk of oral cancer in Egypt.

It has been suggested that nitrate and nitrite may play a role in the etiology of human oral cancer. We investigated whether salivary nitrate and nitrite and the activity of nitrate reductase (NRase) may affect the risk of oral cancer in Egypt, an area with high levels of environmental nitrosating agents. Levels of salivary nitrite (8.3 +/- 1.0 micrograms/ml) and nitrate (44 +/- 3.7 micrograms/ml) and activity of NRase (74 +/- 10 nmol/ml/min) were significantly (P < 0.05) higher in oral cancer patients (n = 42) compared to control Egyptian healthy individuals (n = 40, nitrite = 5.3 +/- 0.3 micrograms/ml, nitrate = 27 +/- 1.2 micrograms/ml, and NRase activity = 46 +/- 4 nmol/ml/min). The adjusted odds ratio (OR) and the 95% confidence intervals (C.I.) for risk of oral cancer, categorized by the levels of salivary nitrate and nitrite and NRase activity, showed a higher cancer risk associated with nitrite > 7.5 micrograms/ml (OR: 3.0, C.I.: 1.0-9.3), nitrite > 40 micrograms/ml (OR: 4.3, C.I.: 1.4-13.3) and NRase activity > 50 nmol/ml/min (OR: 2.9, C.I.: 1.1-7.4). Our findings suggest that increased consumption of dietary nitrate and nitrite is associated with elevated levels of salivary nitrite. Together with the increased activity of salivary NRase, these observations may explain, at least in part, the role of nitrate and nitrite in the development of oral cancer in individuals from an area with a high burden of N-nitroso precursors.

Adult↗

PubMed2005

Validation of nitrite and nitrate measurements in exhaled breath condensate.

BACKGROUND: Inflammatory markers in exhaled breath condensate (EBC) are investigated as a non-invasive approach to monitoring of inflammation in the respiratory tract. EBC concentrations of nitrite and nitrate, the stable end products of oxidative metabolism of nitric oxide, are increased in patients with asthma, especially during acute exacerbations. OBJECTIVES: To examine methodological aspects of nitrite and nitrate measurements in EBC such as sample collection, storage and analysis. METHODS: In a randomized study, EBC was collected twice within 1 h (with and without a nose clip) in 20 healthy adults and 20 patients with well-controlled asthma and no symptoms of allergic rhinitis. Nitrite and nitrate were assayed by ionex chromatography and fluorimetrically after derivatization with diaminonaphthalene. RESULTS: The geometric mean [exp (mean +/- SD)] EBC levels of nitrite and nitrate in healthy subjects [4.3 (3.0-6.1) and 11.0 (5.3-22.7) micromol/l] and patients [4.6 (2.6-7.3) and 8.7 (3.2-23.8) micromol/l] did not differ (p = 0.13). Wearing a nose clip (p = 0.3) did not influence nitrite and nitrate concentrations. The mean intra-subject %CVs of EBC concentrations of nitrite were 26 and 21% in healthy subjects and patients, while those of nitrate achieved 49 and 88%, respectively. CONCLUSIONS: Ionex chromatography of nitrite and nitrate requires no sample pretreatment and provides comparable results as a more laborious diaminonaphthalene method. EBC samples should be kept cold (8 degrees C) and analyzed for nitrite and nitrate within 24 h of collection or stored in the freezer and thawed preferably only once. Wearing a nose clip during EBC collection has no influence on nitrite and nitrate concentrations. Short-term repeatability of nitrite and nitrate measurements was worse compared to published data on exhaled nitric oxide.

Adult↗

PubMed2006

Early intravenous infusion of sodium nitrite protects brain against in vivo ischemia-reperfusion injury.

BACKGROUND AND PURPOSE: The rate of nitric oxide (NO) generation from nitrite is linearly dependent on reductions in oxygen and pH levels. Recently, nitrite-derived NO has been reported to exert a profound protection against liver and heart ischemia-reperfusion injury. In this study, we hypothesized that nitrite would be reduced to NO in the ischemic brain and exert NO-dependent neuroprotective effects. METHODS: Cerebral ischemia-reperfusion injury was induced by intraluminal thread occlusion of middle cerebral artery in the adult male rats. Solutions of sodium nitrite were infused intravenously at the time of reperfusion. Sodium nitrate and carboxy-PTIO (30 minutes before ischemic surgery), a direct NO scavenger, were infused for comparisons. RESULTS: Nitrite reduced infarction volume and enhanced local cerebral blood flow and functional recovery. The effects were observed at concentrations of 48 nmol and 480 nmol, but not at 4800 nmol nitrite and 480 nmol nitrate. The neuroprotective effects of nitrite were inhibited completely by the carboxy-PTIO. The 480 nmol nitrite attenuated dihydroethidium activity, 3-nitrotyrosine formation, and lipid peroxidation in the ischemic brain. CONCLUSIONS: Nitrite exerted profound neuroprotective effects with antioxidant properties in the ischemic brains. These results suggest that nitrite, as a biological storage reserve of NO, may be a novel therapeutic agent in the setting of acute stroke.

Animals↗

PubMed1993

Monitoring nitrite, N-nitrosodiethanolamine, and mutagenicity in cutting fluids used in the metal industry.

We carried out an integrated environmental/biological monitoring program to evaluate cancer hazards among metal industry workers exposed to cutting fluids. Several cutting fluids were sampled according to response to a semiquantitative nitrite rapid test in metal factories in central Italy. The nitrite-positive samples were analyzed for nitrite and nitrosodiethanolamine (NDELA) content and mutagenic activity. The nitrite-negative samples were analyzed only for mutagenicity. Of the total samples, 20.6% were nitrite positive, and all contained NDELA. However, nitrite content was not quantitatively predictive of the NDELA content, which varied enormously among samples (0.3-1900 mg/kg). Nitrite-negative samples were always nonmutagenic. Mutagenicity was found in half the NDELA-containing samples but was not related to nitrite or NDELA content. Nitrite screening of cutting fluids in the field is an interesting method for identifying samples that potentially contain NDELA and other unknown mutagens and, when performed with short-term mutagenicity tests, nitrite screening seems to be a valid tool by which industrial managers and health officers could minimize the health hazards associated with occupational exposure to cutting fluids.

Diethylnitrosamine↗

PubMed2007

Nitrite-derived nitric oxide protects the rat kidney against ischemia/reperfusion injury in vivo: role for xanthine oxidoreductase.

In normal conditions, nitric oxide (NO) is oxidized to the anion nitrite, but in hypoxia, this nitrite may be reduced back to NO by the nitrite reductase action of deoxygenated hemoglobin, acidic disproportionation, or xanthine oxidoreductase (XOR). Herein, is investigated the effects of topical sodium nitrite administration in a rat model of renal ischemia/reperfusion (I/R) injury. Rats were subjected to 60 min of bilateral renal ischemia and 6 h of reperfusion in the absence or presence of sodium nitrite (30 nmol) administered topically 1 min before reperfusion. Serum creatinine, serum aspartate aminotransferase, creatinine clearance, fractional excretion of Na(+), and plasma nitrite/nitrate concentrations were measured. The nitrite-derived NO-generating capacity of renal tissue was determined under acidic and hypoxic conditions by ozone chemiluminescence in homogenates of kidneys that were subjected to sham, ischemia-only, and I/R conditions. Nitrite significantly attenuated renal dysfunction and injury, an effect that was abolished by previous treatment of rats with the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazole-1-oxyl-3-oxide (2.5 mumol intravenously 5 min before ischemia and 50 nmol topically 6 min before reperfusion). Renal tissue homogenates produced significant amounts of NO from nitrite, an effect that was attenuated significantly by the xanthine oxidoreductase inhibitor allopurinol. Taken together, these findings demonstrate that topically administered sodium nitrite protects the rat kidney against I/R injury and dysfunction in vivo via the generation, in part, of xanthine oxidoreductase-catalyzed NO production. These observations suggest that nitrite therapy might prove beneficial in protecting kidney function and integrity during periods of I/R such as those encountered in renal transplantation.

Animals↗

PubMed2001

Influence of turkey meat on residual nitrite in cured meat products.

A response surface experimental design was employed to estimate residual nitrite level at various initial nitrite concentrations, percent turkey meat in the formula, and heat quantity (F) values using a typical wiener as the test system. Pork and mechanically separated turkey were used as the meat ingredients. Residual nitrite and pH were measured at day 1, 7 days, 14 days, and 49 days after processing. Protein, fat, salt, moisture, and CIE (L*a*b*) color values were also determined. Results showed that the effect of turkey meat on residual nitrite level was significant (P < 0.01). An increased amount of turkey meat in the formula resulted in lower residual nitrite levels at a fixed pH. The residual nitrite level was initially proportional to initial nitrite concentration, but it became a nonsignificant factor during longer storage time. Differences in heat quantity had a significant effect (P < 0.05) on residual nitrite level initially. Greater heat quantity decreased residual nitrite level in finished cured meat products at a fixed pH. However, this effect became nonsignificant during longer storage. Reduction of residual nitrite in wieners because of turkey meat addition at a fixed pH was due to characteristics of the turkey tissue, but the mechanism of action remains unknown. It was also established that commercial wieners had a higher pH if poultry meat was included in the formulation.

Animals↗

PubMed2002

Evidence that ingested nitrate and nitrite are beneficial to health.

The literature was reviewed to determine whether ingested nitrate or nitrite may be detrimental or beneficial to human health. Nitrate is ingested when vegetables are consumed. Nitrite, nitrate's metabolite, has a long history of use as a food additive, particularly in cured meat products. Nitrite has been a valuable antibotulinal agent in cured meats and may offer some protection from other pathogens in these products as well. Nitrite's use in food has been clouded by suspicions that nitrite could react with amines in the gastric acid and form carcinogenic nitrosamines, leading to various cancers. Nitrate's safety has also been questioned, particularly with regard to several cancers. Recently, and for related reasons, nitrite became a suspected developmental toxicant. A substantial body of epidemiological evidence and evidence from chronic feeding studies conducted by the National Toxicology Program refute the suspicions of detrimental effects. Recent studies demonstrate that nitrite, upon its ingestion and mixture with gastric acid, is a potent bacteriostatic and/or bactericidal agent and that ingested nitrate is responsible for much of the ingested nitrite. Acidified nitrite has been shown to be bactericidal for gastrointestinal, oral, and skin pathogenic bacteria. Although these are in vitro studies, the possibility is raised that nitrite, in synergy with acid in the stomach, mouth, or skin, may be an element of innate immunity.

Anti-Bacterial Agents↗