Effect of Sodium Chloride, Sodium Nitrite and Sodium Nitrate on the Infectivity of Hepatitis E Virus

Hepatitis E virus (HEV) infection can cause acute and chronic hepatitis in humans. The zoonotic HEV genotype 3, which is highly prevalent in Europe, is mainly transmitted by consumption of raw meat and raw meat products produced from infected pigs or wild boars. High salt concentrations represent an important measure to preserve meat products and to inactivate foodborne pathogens. Here, an HEV preparation in phosphate-buffered saline (PBS) was subjected to different salt concentrations and the remaining infectivity was measured in a cell culture assay. Treatments with up to 20% sodium chloride for 24 h at 23 °C, with and without addition of 0.015% sodium nitrite or 0.03% sodium nitrate, did not lead to virus inactivation as compared to PBS only. Conditions usually applied for short-term and long-term fermented raw sausages were simulated by incubation at 22 °C for up to 6 days and at 16 °C for up to 8 weeks, respectively. Only 2% sodium chloride with 0.015% sodium nitrite showed a weak (< 1 log₁₀), but significant, infectivity reduction after 2 and 4 days as compared to PBS only. Addition of 2% sodium chloride and 0.03% sodium nitrate showed a slight, but not significant, decrease in infectivity after 2 and 8 weeks as compared to PBS only. In conclusion, HEV is highly stable at high salt concentrations and at salt conditions usually applied to preserve raw meat products.

Enhancing colour and oxidative stabilities of reduced-nitrite turkey meat sausages during refrigerated storage using fucoxanthin purified from the Tunisian seaweed Cystoseira barbata

The present study investigated the angiotensin-I converting enzyme (ACE) inhibitory activity and the antioxidant properties, in vitro and in cured meat sausages containing reduced levels of sodium nitrite, of fucoxanthin extracted from the Tunisian brown seaweed Cystoseira barbata (CBFX). Results revealed that CBFX exhibited great scavenging activities against DPPH free radicals (EC50 = 136 μg/ml), peroxyl radicals in the linoleate-β-carotene system (EC50 = 43 μg/ml) and hydroxyl radicals generated by Fenton reaction (DNA nicking assay). A considerable ferric reducing potential was also recorded for CBFX (EC50 = 34 μg/ml). It is interesting to note that CBFX was found to modulate the ACE activity, which is the key enzyme involved in the blood pressure regulation, with an EC50 of 5 μg/ml. When fucoxanthin was supplemented, the concentration of sodium nitrite added to cured turkey meat sausages was reduced from 150 to 80 ppm, coupled with the enhancement of colour and oxidative stabilities. Thus, CBFX, with noticeable antioxidant and antihyertensive effects, could be used as a natural additive in functional foods to alleviate potential human health hazards caused by carcinogenic nitrosamines formation.

Fabrication of an electrochemical platform based on the self-assembly of graphene oxide-multiwall carbon nanotube nanocomposite and horseradish peroxidase: direct electrochemistry and electrocatalysis

A novel hybrid nanomaterial (GO-MWNTs) was explored based on the self-assembly of multiwall carbon nanotubes (MWNTs) and graphene oxide (GO). Compared with pristine MWNTs, such a nanocomposite could be well dispersed in aqueous solution and exhibit a negative charge. Driven by the electrostatic interaction, positively charged horseradish peroxidase (HRP) could then be immobilized onto GO-MWNTs at the surface of a glassy carbon (GC) electrode to form a HRP/GO-MWNT/GC electrode under mild conditions. TEM was used to characterize the morphology of the GO-MWNT nanocomposite. UV-vis and FTIR spectra suggested that HRP was immobilized onto the hybrid matrix without denaturation. Furthermore, the immobilized HRP showed enhanced direct electron transfer for the HRP-Fe(III)/Fe(II) redox center. Based on the direct electron transfer of the immobilized HRP, the HRP/GO-MWNT/GC electrode exhibited excellent electrocatalytic behavior to the reduction of H(2)O(2) and NaNO(2), respectively. Therefore, GO-MWNTs could provide a novel and efficient platform for the immobilization and biosensing of redox enzymes, and thus may find wide potential applications in the fabrication of biosensors, biomedical devices, and bioelectronics.

A simple and rapid spectrophotometric method for the determination of nitrite by its decolorizing effect on peroxovanadate complex

A rapid, simple, and most economical spectrophotometric method was proposed for the determination of nitrite in various water samples, soil samples, and roots of leguminous plants. The method is based on decolorizing effect of nitrite on complex formed between hydrogen peroxide and vanadate in acidic medium. The decolorization of that complex by nitrite was exploited to monitor the reaction spectrophotometrically at 470 nm. The method was optimized for effect of concentrations of ammonium metavanadate, hydrogen peroxide, various acids, concentrations of sulphuric acid, order of reagents addition and color stability. The color of the complex was found to be stable for about 2 days, and the stability constant of the complex was also calculated by modified Job's method. The linearity range of the calibration graph was over 6.67-66.7 microg ml(-1) of nitrite with molar absorptivity, 0.276 x 10(3) mol(-1) l cm(-1) and Sandell's sensitivity, 0.1667 microg cm(-2). The method was applied successfully for the determination of nitrite in soil samples, various wastewater samples and roots of leguminous plants.

Thioredoxin and lipoic acid catalyze the denitrosation of low molecular weight and protein S-nitrosothiols

The nitrosation of cellular thiols has attracted much interest as a regulatory mechanism that mediates some of the pathophysiological effects of nitric oxide (NO). In cells, virtually all enzymes contain cysteine residues that can be subjected to S-nitrosation, whereby this process often acts as an activity switch. Nitrosation of biological thiols is believed to be mediated by N2O3, metal-nitrosyl complexes, and peroxynitrite. To date, however, enzymatic pathways for S-denitrosation of proteins have not been identified. Herein, we present experimental evidence that two ubiquitous cellular dithiols, thioredoxin and dihydrolipoic acid, catalyze the denitrosation of S-nitrosoglutathione, S-nitrosocaspase 3, S-nitrosoalbumin, and S-nitrosometallothionenin to their reduced state with concomitant generation of nitroxyl (HNO), the one-electron reduction product of NO. In these reactions, formation of NO and HNO was assessed by ESR spectrometry, potentiometric measurements, and quantification of hydroxylamine and sodium nitrite as end reaction products. Nitrosation and denitrosation of caspase 3 was correlated with its proteolytic activity. We also report that thioredoxin-deficient HeLa cells with mutated thioredoxin reductase denitrosate S-nitrosothiols less efficiently. We conclude that both thioredoxin and dihydrolipoic acid may be involved in the regulation of cellular S-nitrosothiols.

Effect of alcoholic extract of Ayurvedic herb Tinospora cordifolia on the proliferation and myeloid differentiation of bone marrow precursor cells in a tumor-bearing host

The present study investigates the effect of in vivo administration of alcoholic extract of Tinospora cordifolia whole plant (ALTC) on the proliferation and myeloid differentiation of bone marrow hematopoietic precursor cells in mice bearing a transplantable T cell lymphoma of spontaneous origin designated as Dalton's lymphoma (DL). BMC obtained from ALTC administered DL-bearing mice showed an enhanced BMC proliferation and colony forming ability in vitro in response to L929 conditioned medium as a source of colony stimulating factor (CSF). The number of granulocyte-macrophages colony (CFU-GM) was predominantly higher in the cultures of BMC obtained from ALTC administered mice as compared to mice injected with PBS alone. An increase in the count of bone marrow derived macrophages (BMDM) from ALTC administered mice was also observed along with an increase in the count of tumor associated macrophages. The BMDM obtained from ALTC administered mice showed an enhanced response to signal of LPS for activation to produce IL-1 and TNF. This study indicates that the T. cordifolia can influence the myeloid differentiation of bone marrow progenitor cells and the recruitment of macrophages in response to tumor growth in situ.

Kinetics of thermal decomposition of 4-carboxyl-2,6-dinitrobenzenediazonium ion (CDNBD)

The kinetics of thermal decomposition of 4-carboxyl-2,6-dinitrobenzenediazonium ion (CDNBD), an arenediazonium ion newly developed as a derivatizing reagent for drug analysis, are described. The arenediazonium ion, in an optimized concentrated sulfuric acid/orthophosphoric acid medium, was incubated for various time intervals at 30 degrees, 45 degrees, 55 degrees , 65 degrees , 75 degrees, and 85 degrees C. The amount of ion left after each time interval was quantified selectively by colorimetric assay at 490 nm, using mefenamic acid as a model diazo-coupling component. The rate constants for the decomposition were determined graphically. An Arrhenius plot was used to delineate the dependence of the rate constant on temperature and to predict the half-life at 25 degrees C and lower temperatures. The diazonium ion decomposed by first-order kinetics. The rate constants of decomposition, which increased progressively with temperature, were 3.18 +/- 0.41 x 10(-5), 1.19 +/- 0.07 x 10(-4), 4.87 +/- 0.15 x 10(-4), 12.88 +/- 0.73 x 10(-4), and 21.32 +/- 2.74 x 10(-4) (s(-1)) with corresponding half-lives of 363, 97.06, 23.72, 8.97, and 5.42 min at 30 degrees, 45 degrees, 55 degrees, 65 degrees, and 75 degrees C, respectively. CDNBD is highly stable in concentrated acid medium, with half-life values of about 10 h, 10 days, and 7.3 months at 25 degrees, 0 degrees, and -20 degrees C, respectively. The reagent stability profile shows that it could be readily adapted for routine applications in instrumental chemical analysis.

Comparative experimental analysis of composite pulses in 14N NQR

Experimental results of comparing composite pulses in nitrogen-14 NQR, that are analogous to common 90 degrees RF pulses in powder, are presented. All tested pulses have been taken from publications in journals. Comparative diagrams of the measurement results for induction signals and echo signals are presented. The results of the measurements demonstrate that the best outcomes are achieved when the composite pulse (45)0(95)180(164)0 is used.

The fate of added nitrate used in the manufacture of Emmental cheese

The aim of this study was to observe the dynamics of nitrates and nitrites during the six stages of manufacture of Emmental cheeses. Samples were taken of untreated milk, of pasteurized milk, of milk with nitrates added, of pressed cheese curd, of whey, of maturing cheese and of the final product. The samples were drawn from a commercial operation in a cheese factory in the eastern part of Slovakia. The mean NaNO2 content in untreated and in pasteurised milk was 0.2 and 0.1 mg kg-1, respectively and the mean NaNO3 content was 0.9 and 0.9 mg kg-1 respectively. Nitrates were added to the milk to prevent 'blowing' of hard cheese by micro organisms. In milk with nitrate added the mean content was 81.2 mg kg-1 NaNO3; the maximum value being 90.0 mg kg1 NaNO3. After pressing, the mean value of nitrate was found to be 20.6 mg kg-1 NaNO3. A considerable quantity of nitrates passed into the whey, where the mean nitrate content was 67.0 mg kg-1 NaNO3. The final product had a markedly decreased content of nitrates (3.3 mg kg-1 NaNO3) and nitrites (0.2 mg kg-1 NaNO2) when compared with the values in cheese during maturation (11.3 mg kg-1 NaNO3; 0.4 mg kg-1 NaNO2).

Measurement of total nitric oxide metabolite (NO(x)(-)) levels in vivo

The measurement of the total level of nitric oxide (NO) metabolite (NO(x)(-)) by microdialysis has recently been used to assess the production of NO in the in vivo brain [D. Luo, S. Knezevich, S.R. Vincent, N-Methyl-D-aspartate-induced nitric oxide release: an in vivo microdialysis study, Neuroscience, 57 (1993), 897-900; K. Ohta, N. Arai, M. Shibata, J. Hamada, S. Komatsumoto, K. Shimazu, Y. Fukuuchi, A novel in vivo system for consecutive measurement of brain nitric oxide production combined with the microdialysis technique, Neurosci. Lett., 176 (1994), 165-168; K. Shintani, S. Kanba, T. Nakai, K. Sato, G. Yagi, R. Kato, M. Arai, Measurement by in vivo microdialysis of nitric oxide release in the rat cerebellum, J. Psychiatr. Neurosci., 3 (1994), 217-221; H. Togashi, K. Mori, K. Ueno, M. Matsumoto, N. Suda, H. Saito, M. Yoshika, Consecutive evaluation of nitric oxide production after transient cerebral ischemia in the rat hippocampus using in vivo brain microdialysis, Neurosci. Lett., 240 (1998), 53-57]. Although several methods are available for detecting NO(x)(-) levels in dialysates, these methods are either not sensitive enough or require expensive experimental equipment. The method described herein provides a convenient and sensitive procedure for determining NO(x)(-) levels in dialysates. This method is useful for the in vivo study of NO production from various brain regions in various pathological conditions, and can be applied to other tissues.

N-Nitroso compounds in the diet

N-Nitroso compounds were known almost 40 years ago to be present in food treated with sodium nitrite, which made fish meal hepatotoxic to animals through formation of nitrosodimethylamine (NDMA). Since that time, N-nitroso compounds have been shown in animal experiments to be the most broadly acting and the most potent group of carcinogens. The key role of nitrite and nitrogen oxides in forming N-nitroso compounds by interaction with secondary and tertiary amino compounds has led to the examination worldwide of foods for the presence of N-nitroso compounds, which have been found almost exclusively in those foods containing nitrite or which have become exposed to nitrogen oxides. Among these are cured meats, especially bacon-and especially when cooked; concentrations of 100 micrograms kg(-1) have been found or, more usually, near 10 micrograms kg(-1). This would correspond to consumption of 1 microgram of NDMA in a 100-g portion. Much higher concentrations of NDMA (but lower ones of other nitrosamines) have been found in Japanese smoked and cured fish (more than 100 micrograms kg(-1)). Beer is one source of NDMA, in which as much as 70 micrograms l(-1) has been reported in some types of German beer, although usual levels are much lower (10 or 5 micrograms l(-1)); this could mean a considerable intake for a heavy beer drinker of several liters per day. Levels of nitrosamines have been declining during the past three decades, concurrent with a lowering of the nitrite used in food and greater control of exposure of malt to nitrogen oxides in beer making. There have been declines of N-nitroso compound concentrations in many foods during the past two decades. The small amounts of nitrosamines in food are nonetheless significant because of the possibility-even likelihood-that humans are more sensitive to these carcinogens than are laboratory rodents. Although it is probable that alkylnitrosamides (which induce brain tumors in rodents) are present in cured meats and other potentially nitrosated products in spite of much searching, there has been only limited indirect evidence of their presence.

[The in vitro effect of ascorbic acid on sodium nitrite intoxication]

The in vitro effect of ascorbic acid on the content of sodium nitrite in relation to pH and time of incubation and also effect of sodium nitrite on the total content of vitamin C as a sum of both reduced and oxidized forms was demonstrated. Ascorbic acid in respective quantities of 60 mg, 120 mg, 180 mg and sodium nitrite in quantity of 12 mg were added to the in vitro simulated stomach content at pH 1.5, 2.5, 3.5. The control samples were tested without addition of ascorbic acid. The Griess method for determination of nitrite and the Tillmans method with Pijanowski's modification were used for the determination of vitamin C. It was found that the choice of lower pH significantly decreased the level of nitrite in the control samples produced the disappearance of nitrite increased depending on the quantity of ascorbic acid added to the sample and on pH. The total content of vitamin C did not change after adding of sodium nitrite to the samples. The performed studies suggested a positive effect of ascorbic acid decreasing of the nitrite level.

Survival of Escherichia coli O157:H7 during the manufacture of pepperoni

This study investigated the growth and survival of Escherichia coli O157:H7 during the manufacture of pepperoni to determine whether a 5-log10-unit decline in numbers, as recommended by the U.S. Food Safety and Inspection Service (FSIS), could be achieved. A range of pepperoni formulations with variations in salt (2.5 to 4.8%) and sodium nitrite (100 to 400 ppm) levels, and with pH (4.4 to 5.6) adjusted by manipulation of dextrose concentrations were prepared. The batters produced were inoculated with E. coli O157:H7 380-94 at a level of approximately 6.70 log10 CFU/g; changes in pathogen numbers, pH, titratable acidity, and sodium nitrite concentrations were monitored during fermentation and drying. With the standard commercial formulation (i.e., 2.5% salt, 100 ppm sodium nitrite, pH 4.8) E. coli O157:H7 numbers declined by approximately 0.41 log10 CFU/g during fermentation and a further 0.43 log10 CFU/g during subsequent drying (7 days). A regression equation was fitted to the data which showed significantly (P < 0.001) greater reductions in pathogen numbers in samples with increased salt and sodium nitrite contents and lowered pH. However declines were in all cases less than the target reduction of 5 log10 CFU/g.

N-nitrosodibenzylamine in boneless hams processed in elastic rubber nettings

Boneless hams processed in elastic rubber nettings contain high levels of nitrosamines in the outermost layer. The precursors of the nitrosamines are zinc dibutyl- or dibenzyldithlocarbamate used as a vulcanizing agent in the formulation of the rubber. The outermost layer from 59 commercial hams was analyzed for 11 volatile nitrosamines including N-nitrosodibutylamine (NDBA) and N-nitrosodibenzylamine (NDBzA). The principal nitrosamine, NDBzA, was detected in 32 (54%) ham samples at the 10-100 ppb range; it exceeded 100 ppb in 18 (30%) samples, with the highest at 512.2 ppb. No nitrosamine was detected in 7 of 59 ham samples. To determine the cause of the high NDBzA values, various types of unused nettings (from different manufacturers) accompanying the samples were analyzed for nitrosamines. No correlation was found between the NDBzA content of the hams and the nettings. The results suggest that the problem of nitrosamine formation in these products has not yet been resolved.

Accidental acute fatal sodium nitrite poisoning

An accidental food poisoning outbreak occurred resulting in the death of 14 of the 22 affected persons. Chemical analysis of food materials revealed the presence of sodium nitrite and potassium arsenate. Analysis of urine, gastric contents, liver and kidney, collected at the time of autopsy, confirmed the presence of these chemical substances in high concentrations. Epidemiological data indicated that the food poisoning occurred due to the accidental use of sodium nitrite and potassium arsenate instead of table salt in the preparation of tamarind (Tamarindus indica) soup.

[Evolution of the microbiological parameters of cured ham]

The main microbiological and physico-chemical parameters in dry-salted ham previously selected were determined along the elaboration process. All determinations were performed at 2 levels: surface and internal. All bacterial groups showed a similar behaviour, increasing along the first stages up to the third month of drying, then decreasing to numbers similar to the initial ones. Only the halotolerants maintained fairly high numbers during last stages. Some groups were almost absent at internal levels. The hazardous bacteria showed different behaviour: whereas the faecal streptococci were fairly abundant during the whole study, coliforms almost disappeared at the final stages. During the elaboration process at different stages of ripening they were analysed in order to know the moulds population at surface level. Aspergillus and Penicillium were the dominant genera. The latter, mainly represented by 10 species, dominated during the first stages of elaboration. Aspergillus was present throughout the whole making process. The glaucus group was clearly dominant at the final stages due to the low aw values together with the high NaCl percentages. Aspergillus halophilicus was the most abundant species identified (18%) and the most frequently isolated at the final stages.

A simplified method for the determination of nitric oxide in biological solutions

A new simplified procedure for determination of nitric oxide (NO) in biological solutions is described utilizing a new reducing system of nitric oxide prior to chemiluminescence. Advantages of the new method makes heating of the reducing solution unnecessary and avoids cooling and condensation of generated vapors. Only traces of acid with a high boiling point are used. The method permits analysis of small sample volumes (200 microL). The basal production of nitric oxide by freshly harvested endothelial cells ranged from 100 to 880 picomoles.

Investigations on N-nitrosopyrrolidine in dry-cured bacon

Dry-cured or "country-style" bacon is a low volume specialty product typically made by small producers whose production practices vary widely. These practices include the direct application of dry-cure formulations containing varying concentrations of salt, sugar, flavoring agents, sodium nitrite, and sometimes sodium nitrate, and the use of lengthy curing and processing times. Because of the possibility of generating higher levels of N-nitrosopyrrolidine (NPYR) after frying in this product type compared with pump-cured bacon, an investigation was carried out on dry-cured bacon obtained from cooperating state or federally inspected establishments. Three different samples from each of the 16 plants were analyzed. Only one sample from each of 2 different producers exceeded the Food Safety and Inspection Service (FSIS) action level of 17 ppb NPYR, indicating that the majority of samples tested were in compliance. A significant correlation (P less than 0.01) was found between residual NaNO2 prior to frying and NPYR after frying. The elimination of added nitrate in the dry-cure formulations is recommended.

Formation of 2,6-dimethoxy-1,4-benzoquinone, a highly genotoxic compound, from the reaction of sodium nitrite with the sympathomimetic drug dimethophrine in acidic aqueous solution

Because of the genotoxic effects shown by Dimethophrine (DMP) nitrosation mixtures, the interaction between DMP hydrochloride and sodium nitrite in acidic aqueous solution at 37 degrees was investigated in a wide range of reagent concentrations and molar ratios, reaction times and pH values. Actually, depending on the operating conditions, it was possible to detect variable amounts of 2,6-dimethoxy-1,4-benzoquinone (DMBQ), a highly genotoxic compound, but no N-nitrosoderivative. The highest conversion of DMP into DMBQ was obtained when concentrated acidic solutions of DMP and NaNO2 (molar ratio 1:1.9) reacted at pH 3.0-4.0 (50-60% after 1 hour, depending on the pH conditions). When DMP hydrochloride and NaNO2 (molar ratio 1:0.95) were allowed to react at pH 3.5 in a more diluted solution, to mimic gastric conditions, the conversion of DMP into DMBQ after 20 min was about 3%. The breakdown of DMP can be prevented by adding suitable amounts of ascorbic acid to the reagents.

Effect of water on nitrosamine formation in fried bacon

Bacon was soaked in water before frying and the effect on the formation of N-nitrosodimethylamine and N-nitrosopyrrolidine was studied. Soaking for 5 minutes reduced N-nitrosopyrrolidine levels by as much as 52%, but had little effect on N-nitrosodimethylamine levels. Longer soaking periods, up to 17 hours, gave the same results.

Sensoric and chemical limits in lowering the dose of sodium nitrite in the process of pork curing

The specific cured meat odour and taste stimulus thresholds in pork containing different quantities of sodium nitrite were determined in relation to the residual nitrite level and relative contents of nitrosylpigments in meat. It was stated, that the specific odour and taste detection thresholds were equal to 10 and below 10 mg NaNO2/kg of meat, respectively, and the specific odour and taste recognition thresholds were equal to 26 and 21 mg NaNO2/kg of meat, respectively. The detection and recognition thresholds corresponded to 2.4 and 8.5 mg of residual nitrite in meat, respectively. In all the cases the relative contents of nitrosylpigments were above 50%. Taking into account the maintening of specific cured meat odour and taste, the dose of sodium nitrite in pork curing may be lowered to 30 mg/kg.

Effect of N-nitrosothiazolidine-4-carboxylic acid on formation of N-nitrosothiazolidine in uncooked bacon

N-Nitrosothiazolidine-4-carboxylic acid (NTHZC) was recently identified in a variety of smoked fish and cured meat products. While the toxicological properties of NTHZC are currently unknown, it has been speculated that N-nitrosothiazolidine (NTHZ) in fried bacon may be caused in part by decarboxylation of NTHZC. A limited survey of uncooked cured meat products failed to demonstrate any correlation between levels of NTHZC and NTHZ. However, NTHZC levels were significantly higher, ranging from 8 to 1400 ppb, than the corresponding NTHZ levels, which ranged from less than 2 to 18 ppb. Decarboxylation of NTHZC to NTHZ in a model system occurs at 110 degrees C, which is significantly higher than the average bacon processing temperature of 54 degrees C, but lower than the normal frying temperature of 177 degrees C recommended for bacon. Results from both model system and frying experiments with NTHZC and its precursors suggest that NTHZC decarboxylation to NTHZ is not the principal pathway to NTHZ formation in uncooked bacon.

Simultaneous determination of nitrate and nitrite in toothpastes by high-performance liquid chromatography

A stability-indicating analytical method is described for the simultaneous determination of nitrate, and if present, its reductive degradation product, nitrite, in toothpastes. Nitrate and nitrite were extracted from the toothpaste using distilled water and separated from other water-soluble excipients by two RP-8 columns (250 mm X 4 mm i.d.) using a mobile phase containing 0.2% (w/v) sodium acetate and 2.5% (v/v) glacial acetic acid in distilled water. A UV detector set at 313 nm was used for quantitation. The method was applied to commercial toothpastes containing 5% potassium nitrate and yielded an average recovery of 100.1% with a relative standard deviation of 1.43%. Average recovery of nitrate and nitrite from spiked samples were 100.6% and 96.4%, respectively. The minimum detectable concentration for nitrite was 50 micrograms/g of toothpaste.

Comparison of three methods for determination of N-nitrosopyrrolidine in fried dry-cured bacon

The recently developed Eastern Regional Research Center ( ERRC ) dry column chromatographic procedure for determining N-nitrosopyrrolidine (NPYR) in fried cure-pumped bacon was evaluated for its applicability to fried dry-cured bacon. The method was then compared with 2 established procedures for volatile nitrosamine analysis in cured meat products: the multidetection thermal energy analyzer (MD) method and the mineral oil distillation (MOD) screening procedure. No significant difference (P less than 0.05) in NPYR values was found between the ERRC and MD procedures, but significant differences were found between the ERRC and MOD procedures and between the MOD and MD procedures. No artifactual nitrosamine formation was found in the ERRC procedure, but significant amounts were found in samples analyzed by the MOD procedure. The ERRC method was demonstrated to be rugged and very rapid. It is proposed that the ERRC method replace the MOD method as the official screening procedure for NPYR in fried bacon.

[Mechanism of the formation of nitrosyl complexes of non-heme iron in animal tissues in vivo]

Further investigations were carried out into the formation mechanism of nitrosyl complexes of non-heme iron (complexes 2.03) in rat liver and blood at intrauterine injection of aqueous solutions of nitrosyl complexes of iron with cysteine, thiosulphate, phosphate, ATP and hydroxyl, as well as at keeping the animals on nitrite and iron diet. It has been found that 5-6 hours after the injection of iron nitrosyl complexes with cysteine/the shape of ESR signal with gav = 2.03 in the liver becomes identical to the shape of the signal obtained after adding nitrite and iron to the animal food. Therefore it is assumed that in spite of different methods of induction, the 2.03 complexes formed in these experiments are identical in structure and localization. The assumption was proved as to initial formation of Fe-NO in the blood with subsequent transition to SH-groups of liver proteins. It is suggested that complexes 2.03 in vivo are concerned with a specific type of protein.

Nitrate and nitrite contents in Cuban cheese of the Gouda type

The nitrate and nitrite contents in cheese of the Gouda type, produced by the Milk Complex of Havanna, were investigated and compared with those found in 5 types of imported cheese consumed in Cuba. No significant differences were found in the mean value (mean) of NaNO3, whereas in the mean value (mean) of NaNO2 differences were found when comparing all cheeses against each other. From these results it is inferred that the consumption of Gouda type cheese does not represent an important contribution to the daily intake of nitrates and nitrites, precursors in the synthesis of cancerogenic N-nitroso compounds.

[Determination of the iodine content in food products using the nitrite-rhodanide method]

The nitrite-rodanide method was suggested to determine the content of iodine in food. It was shown that this method, provided the exposure of the test solutions during colorimetry was appropriately chosen, enables the determination in an aliquot of 0.5 g of both low and high (2-600 microgram/100 ml) concentrations of iodine. The determination of high concentrations can be realized by an ordinary diluting of the solutions under colorimetry.

Distribution and metabolism of ingested NO3- and NO2- in germfree and conventional-flora rats

Germfree and conventional-flora Sprague-Dawley rats were fed sodium nitrate or sodium nitrite in their drinking water (1,000 microgram/ml), and various organs, tissues, and sections of the intestinal tract were assayed for nitrate (NO3-) and nitrite (NO2-) by a spectrophotometric method. When fed NO3-, germfree rats had chemically detectable levels of NO3- (only) in the stomach, small intestine, cecum, and colon. Conventional-flora rats fed NO3- had both NO3- and NO2- in the stomach, but only NO3- in the small intestine and colon. When fed NO2-, germfree rats had both NO3- and NO2- in the entire gastrointestinal tract. Conventional-flora rats fed NO2- had both ions in the stomach and small intestine, but only NO3- in the large intestine. Conventional-flora rats fed NO3- or NO2- had lower amounts of these ions in the gastrointestinal tract than comparably fed germfree rats. Control (non-NO3- or NO2--fed) germfree and conventional-flora rats had trace amounts of NO3- (only) in their stomachs and bladders. These results, in conjunction with various in vitro studies with intestinal contents, suggest that NO3- or NO2- reduction is a function of the normal bacterial flora, whereas NO2- oxidation is attributable to the mammalian host. In addition, the distribution of these ions after their ingestion appears more widespread in the body than previously thought.