Chemistry, safety, and regulatory considerations in the use of nitrite and nitrate from natural origin in meat products - Invited review.

Nitrite and nitrate have been traditionally used for the preservation of meat products because of the effective antimicrobial action of nitrite against Clostridium botulinum, the outgrowth of its spores as well as other bacteria. However, the use of nitrite and nitrate has been questioned in last half century due to the possible generation of N-nitrosamines through reaction of nitrite with secondary amines. Nitrite replacement strategies began in the 70s addressing these issues and instigated searches for natural alternatives to nitrate and nitrite, or for natural sources of nitrite and nitrate such as vegetable extracts. These alternatives have been considered by producers and consumers as an attractive practice even though they may also have some risks. This manuscript reviews and discusses the chemistry, safety, and regulatory considerations in the use of nitrite and nitrate from natural origin for the preservation of meat products.

Analysis of the monitoring status of residual nitrite in meat products in China from 2000 to 2011.

The aim of this article was to analyze the monitoring status of nitrite in meat products consumed from 2000 to 2011 in 24 provinces, autonomous regions or direct-controlled municipalities in China. Statistical analyses were performed on the monitoring status including number, proportion, and distribution of 13,316 samples, of which 11,320 (85%) contained up to 2808.2mg/kg nitrite and 1996 (15%) contained no nitrite. A total of 10,299 samples (77%) qualified for GB/T 5009.33-2003, 2003; however, 3017 samples (23%) contained nitrite at levels higher than the national standard. The districts with high percentage of samples with no nitrite were Shanghai (49%), Beijing (47%), and Liaoning (30%). While the districts with high percentage of meat products containing nitrite at levels exceeding the national standard were Jiangxi (49%), Jiangsu (33%), Shandong (29%) and Sichuan (29%). Therefore, the status of residue nitrite in meat products is of concern.

Chemical safety of meat and meat products.

Since the Second World War the consumer behaviour in developed countries changed drastically. Primarily there existed the demand for sufficient food after a period of starvation, afterwards the desire for higher quality was arising, whereas today most people ask for safe and healthy food with high quality. Therefore a united approach comprising consistent standards, sound science and robust controls is required to ensure consumers' health and to maintain consumers' confidence and satisfaction. Chemical analysis along the whole food chain downstream (tracking) from primary production to the consumer and upstream (tracing) from the consumer to primary production is an important prerequisite to ensure food safety and quality. In this frame the focus of the following paper is the "chemical safety of meat and meat products" taking into account inorganic as well as organic residues and contaminants, the use of nitrite in meat products, the incidence of veterinary drugs, as well as a Failure Mode and Effect Analysis (FMEA) system assessing (prioritizing) vulnerable food chain steps to decrease or eliminate vulnerability.

Electrochemical nitrite biosensor based on the immobilization of hemoglobin on an electrode modified by multiwall carbon nanotubes and positively charged gold nanoparticle.

The report is on an electrochemical biosensor with remarkably improved sensitivity toward nitrite. In this strategy, positively charged gold nanoparticle (PCNA) is used in combination with multiwall carbon nanotubes (MWCNT) by electrostatic adsorption for fabricating PCNA/MWCNT films. Then hemoglobin (Hb) biocatalyst will easily be attached to the surface of the combination films aforementioned. After that, the Hb/PCNA films are immobilized onto the Hb/PCNA/MWCNT films through layer-by-layer assembly technique. The (Hb/PCNA)(2)/MWNT/GC electrode thus prepared exhibits enhanced electrocatalytic behavior to the reduction of nitrite at -0.10 V versus SCE in 0.05 M H(2)SO(4) solution. On condition of the low detecting potential and low pH, interference caused by direct electrochemical oxidation or oxidizable substances can be prevented. Therefore, the modified electrode shows fast response time, very high sensitivity, good selectivity and stability. The current response of the sensor increases linearly with nitrite concentration from a range of 3.6 x 10(-6) to 3.0 x 10(-3) M with a detection limit(S /N = 3) of 9.6 x 10(-7) M.

Nitrite and nitrate measurement by Griess reagent in human plasma: evaluation of interferences and standardization.

Nitrite and nitrate represent the final products of nitric oxide (NO) oxidation pathways, and their hematic concentrations are frequently assessed as an index of systemic NO production. However, their intake with food can influence their levels. Nitrite and nitrate could have a role by producing NO, because nitrite can release NO after reaction with deoxyhemoglobin and dietary nitrate can be reduced substantially to nitrite by commensal bacteria in the oral cavity. Different methods have been applied for nitrite/nitrate detection, with the most commonly used being the spectrophotometric assay based on the Griess reagent. However, a reference methodology for these determinations is still missing and many possible interferences have been reported. This chapter assesses how different experimental conditions can influence the results when detecting nitrite and nitrate in human plasma by the Griess assay and provides a simple method characterized by high reproducibility and minimized interferences by plasma constituents.

Quantification of residual nitrite and nitrate in ham by reverse-phase high performance liquid chromatography/diode array detector.

Nitrite and nitrate are used as additives in ham industry to provide colour, taste and protect against clostridia. The classical colorimetric methods widely used to determine nitrite and nitrate are laborious, suffer from matrix interferences and involve the use of toxic cadmium. The use of chromatography is potentially attractive since it is more rapid, sensitive, selective and provides reliable and accurate results. A rapid and cost-effective RP-HPLC method with diode array detector was optimized and validated for quantification of nitrites and nitrates in ham. The chromatographic separation was achieved using a HyPurity C18, 5 microm chromatographic column and gradient elution with 0.01 M n-octylamine and 5mM tetrabutylammonium hydrogenosulphate to pH 6.5. The determinations were performed in the linear range of 0.0125-10.0mg/L for nitrite and 0.0300-12.5 g/L for nitrate. The detection limits were 0.019 and 0.050 mg/kg, respectively. The reliability of the method in terms of precision and accuracy was evaluated. Coefficients of variation lower than 2.89% and 5.47% were obtained for nitrite and nitrate, respectively (n=6). Recoveries of residual nitrite/nitrate ranged between 93.6% and 104.3%. Analysis of cooked and dried ham samples was performed, and the results obtained were in agreement with reference procedures.

Preparation and evaluation of candidate certified reference materials (CRMs) for nutrients in seawater.

Certified reference materials (CRMs) are an essential part of the quality assurance (QA) necessary for the reliable analytical measurement of nutrients in seawater. The CRMs currently available for these analyses are not matrix matched to marine samples. QUASIMEME routinely produces test materials for the nutrients in seawater and nutrients in estuarine water and low-salinity open water Laboratory Performance Studies (LPS) that are both homogeneous and stable. QUASIMEME, in conjunction with Eurofins Scientific, Denmark have produced two reference materials (RMs). The homogeneity testing and preliminary stability studies were carried out by QUASIMEME, and the results are presented in this article. Participants of the QUASIMEME LPS who demonstrated satisfactory long-term performance for the analysis of nutrients in seawater and nutrients in estuarine water and low-salinity open water were invited to take part in the certification exercise. Twenty laboratories returned data, a summary of which is also presented. The certification and long-term stability testing and additional data analysis were carried out by Eurofins Scientific, Denmark, and are outwith the scope of this article and not reported here. Eurofins Scientific, Denmark have marketed these RMs as part of their range of VKI Reference Materials (further information is available from eurofins@eurofins.dk).

[Highly sensitive spectrofluorimetric determination of trace amounts of nitrite with N-(1-naphthyl) ethylenediamine].

A simple and sensitive fluorescence quenching method for the determination of trace nitrite was developed. The method is based on the reaction of NED with nitrite in acidic medium to form a new compound, which has weak fluorescence. The linear range was 1.07-214.0 microg x L(-1) with a 3sigma detection limit of 0.069 microg x L(-1) under the optimum experimental conditions. This proposed method has been applied to the determination of trace amounts of NO2- in tap water and lake water without extraction.

[Content of nitrates and nitrites in whole milk powder in different regions of Poland]. / Zawartosc azotanów i azotynów w pelnym mleku w proszku z róznych rejonów Polski.

The content of nitrites and nitrates in whole milk powder in different regions of Poland was studied. The results obtained depended both on the factory from which the samples originated and on the season of the year. In 34.2% of the samples there was a very low level of nitrates and nitrites (below acceptable level for whole milk powder served to production of modified milk and modified infant formulas). In 64.1% of the samples the level was in accordance with the national standards and in 1.7% of the samples slightly over the limit. 99.2% of the samples were in accordance with the foreign standards.

Estimation of nitrite ions by the formation of aryl nitroanion radicals in the reaction with the aminoarene 3,5-dibromo-4-amino-benzenesulfonic acid by EPR spectroscopy. The use of 15N-nitrite as an internal standard.

The reaction between the aminoarene 3,5-dibromo-4-aminobenzenesulfonic acid (Na-salt) and nitrite ions gives rise to the corresponding nitroanion radical. In the reaction the amino group of the parent substance was replaced by NO2 from the nitrite ions. This leads to two different EPR spectra when the reaction was made with 14N and 15N nitrite. Furthermore, the two spectra were completely separated with no overlaps, a property which was utilised for a quantitative evaluation of samples of 14N nitrite by means of the addition of a known amount of 15N nitrite as an internal standard. Variation of the concentration of the nitroanion radicals was eliminated since the variation will affect the 14N and 15N products to the same extent. The amplitudes of the spectral components M1 = +1 of the 14N spectrum and M1 = +1/2 of the 15N spectrum were used for the evaluation of the 14N nitrite content of the sample.

Dietary nitrite and scavenger antioxidants trace elements.

Rats initially weighing 138 +/- 14 g were fed the following diets for 150 days: control (Co), control plus nitrite-bacon-proline 24 mg/kg, 100 g/kg and 10 mg/kg, respectively (NB), NB plus 0.04 micrograms/g selenium (NBSe) and NB plus 0.020 g/kg ascorbic acid (NBC). The NB diet provoked body weight and feeding efficiency enhancement with a reduction in body density increasing serum lactic acid, uric acid and cholesterol levels. The serum selenium decreased by the presence of NB in the diet. The addition of selenium and ascorbic acid to the NB diet prevented the reduction in body density and also affected uric acid and cholesterol levels. It is suggested that the NB diet has adverse effects and that some of the alterations it causes are prevented by the reducing elements selenium and ascorbic acid.

A rapid and simple method for the measurement of nitrite and nitrate in plasma by high performance capillary electrophoresis.

Quantification of nitric oxide in vivo is difficult because of its short half-life. Instead the oxidised products, nitrite and nitrate, are commonly used as indices of nitric oxide generation. We describe here a simple method for the measurement of nitrite and nitrate in plasma using high performance capillary electrophoresis. Plasma standard curves gave regression coefficients of 0.98 for nitrite and 0.99 for nitrate with an intra-assay coefficient of variance of 4.6% for 50 microM nitrite (n = 10) and 1.2% for 50 microM nitrate (n = 10). The assay allows measurement of nitrite and nitrate in a single analysis requiring minimal sample preparation, and with the sensitivity to detect both basal and physiological changes in plasma nitrite and nitrate.

[Determining the levels of selected pesticides, nitrates, nitrites, ammonium ions, sulfates, chlorides and urea in surface and underground waters. VII]. / Oznaczanie wybranych pestycydów, azotanów, azotynów, jonów amonowych, siarczanów, chlorków i mocznika w wodach powierzchniowych i podziemnych. Cz. VII.

The subjects of the study was determination of the residues of pesticides: lindane, metoxychlor and chlorphenvinphos, nitrates, nitrites, ammonium ions, sulphates, chlorides and urea in surface waters and underground waters in the southeastern part of the Province of Szczecin in 1983-1988. The certain pesticides and urea in none of determined samples of waters were present. The concentrations of nitrates, ammonium and chlorides below the permitted value have been. Nitrites in surface waters and in underground waters in 48 per cent and 82 percent of the samples have been respectively.

Agua potable. Determinación de nitritos por el método espectofotométrico sulfanilamida / Drinking water. Determination of nitrites by the method espectofotométrico \"sulfanilamide\"

Esta Norma tiene por objeto la determinación de nitritos en agua potable por el método espectofotométrico sulfanilamida, es aplicable para aguas en general.