Simultaneous Determination of Nitrate and Nitrite in Fish Products with Improved Sensitivity by Sample Stacking-Capillary Electrophoresis

A fast and reproducible method for the simultaneous determination of nitrate and nitrite ions in canned fish samples by capillary zone electrophoresis has been developed. The sensitivity of the method was increased by applying a sample stacking technique. Optimal separation conditions were selected as 30 mmol L^?1 formic acid and 30 mmol L^?1 sodium sulfate at a pH of 4.0. The separation of nitrate and nitrite ions was achieved within 2.5 min. The limits of detection obtained at a signal-to-noise ratio of 3 for nitrate and nitrite were 0.55 and 0.82 μmol L^?1, while the relative standard deviations of intra-day corrected peak areas were 0.99 and 2.74 %, respectively. Recovery values ranged between 88.7 and 104 % for both ions. The method was successfully applied to canned fish samples, namely tuna, mackerel and sardine.     

A Micro-Flow-Batch Analyzer Using an In-line Cadmium Sponge Microcolumn for the Photometric Determination of Nitrate and Nitrite in Dairy Samples

In this study, a micro-flow-batch analyzer (μFBA) using an in-line cadmium reduction microcolumn for the photometric determination of nitrate and nitrite in dairy samples is described. The method is based on the Griess-Llosvay reaction and measuring of the absorbance at 540 nm using a green LED integrated into the μFBA built in the urethane-acrylate resin. Initially, the nitrite content of the dairy sample is analyzed in the mixing chamber, while the nitrate is reduced to nitrite in cadmium sponge microcolumn coupled to the microsystem. Nitrate content was calculated from the difference between nitrate plus nitrite (expressed as nitrite) and nitrite content. The analytical curve for nitrate and nitrite was linear in the work range of 10.0–100.0 μg L^?1 with a correlation coefficient of 0.992 and 0.998, respectively. The limit of detection and relative standard deviation were estimated at 0.39 μg L^?1 and <1.7 % (n?=?5) for nitrite and 0.41 μg L^?1 and <1.3 % (n?=?5) for nitrate. Comparing with the reference methods, no statistically significant differences were observed when applying the paired t test at a 95 % confidence level. The accuracy was assessed through recovery test (97.7 to 102.9 %). The proposed microsystem-employed in-line cadmium sponge microcolumn presented satisfactory portability, robustness, flexibility, low-cost device, and reduced chemicals consumption compared to recent methods. Thus, μFBA is potentially useful as an alternative for other automatic determinations using in-line pretreatment steps.     

Simultaneous Determination of Nitrite and Nitrate in Milk Samples by Ion Chromatography Method and Estimation of Dietary Intake

The presence of nitrate and nitrite in foods may be considered hazardous after ingestion in the gastrointestinal tract due to their reaction with naturally occurred secondary amines to form potentially carcinogenic nitrosamines. Due to this fact, a new method was developed in this study for the simultaneous determination of nitrite and nitrate in milk samples using by ion chromatography. Proposed mobile phase composed of sodium hydrogen carbonate and sodium carbonate (1.0 and 3.2 mmol/L) with a flow rate of 0.7 ml/min. The average recoveries for nitrate and nitrite were higher than 86 and 88%, respectively. The limit of detection for nitrate and nitrite were 0.24 and 0.09 mg/L, respectively. The results of 102 real milk samples showed nitrate was found in all of the samples (100%) with a mean of 34 ± 11 mg/L, while nitrite was found in none of the samples. The mean intake of nitrate in all age groups was lower than World Health Organization guideline. The present assessment concludes that the maximum contaminant level was equal to 82.8 mg/L nitrate. This method was fast, sensitive and accurate and is capable of being an alternative method in food control laboratories for investigation of nitrite and nitrate content. This is the first study of the determination and survey of nitrite and nitrate and exposure assessment of the Iranian population to nitrite and nitrate level in milk, which was widely used in infants and adolescents as one of the basic food components.     

Dietary Plant Sterols Supplementation Increases In Vivo Nitrite and Nitrate Production in Healthy Adults: A Randomized,Controlled Study

A randomized, double‐blinded, placebo‐controlled and crossover study was conducted to simultaneously measure the effects, 3 h after consumption and after 4‐wk daily exposure to plant sterols‐enriched food product, on in vivo nitrite and nitrate production in healthy adults. Eighteen healthy participants (67% female, 35.3 [mean] ± 9.5 [SD] years, mean body mass index 22.8 kg/m²) received 2 soy milk (20 g) treatments daily: placebo and one containing 2.0 g free plant sterols equivalent of their palmityl esters (β‐sitosterol, 55%; campesterol, 29%; and stigmasterol, 23%). Nitrite and nitrate concentrations were measured in the blood plasma and urine, using stable isotope‐labeled gas chromatography‐mass spectrometry. L‐arginine and asymmetric dimethylarginine concentrations in blood serum were measured using commercially available enzyme immunoassays. Nitrite and nitrate concentrations in blood plasma (nitrite 5.83 ± 0.50 vs. 4.52 ± 0.27; nitrate 15.78 ± 0.96 vs. 13.43 ± 0.81 μmol/L) and urine (nitrite 1.12 ± 0.22 vs. 0.92 ± 0.36, nitrate 12.23 ± 1.15 vs. 9.71 ± 2.04 μmol/L) were significantly elevated after 4‐wk plant sterols supplementation Placebo and 3‐h treatments did not affect the blood plasma and urinary concentrations of nitrite and nitrate. Circulating levels of L‐arginine and asymmetric dimethylarginine were unchanged in the placebo and treatment arms. Total plant sterols, β‐Sitosterol, campesterol, and stigmasterol concentrations were significantly elevated after 4‐wk treatments compared to the placebo and 3‐h treatments. Blood plasma nitrite and nitrate concentrations correlated significantly with the plasma total and specific plant sterol concentrations. Our results suggest that dietary plant sterols, in the combination used, can upregulate nitrite, and nitrate production in vivo.     

Effect of nitrate and nitrite curing salts on lipolysis in dry sausages produced using a rapid fermentation process

 The effect of nitrite and nitrate curing salts on lipolysis in a typical non-smoked Spanish sausage (salchichón), manufactured using a rapid dry fermentation process, was studied. From the results obtained, one could deduce that nitrite and nitrate per se do not affect the endogenous hydrolysis of the lipids during the rapid fermentation process used to produce dry sausage. Polyunsaturated fatty acids (PUFA) are liberated in greater quantities than monounsaturated (MUFA) and saturated (SFA) ones, which suggests that they are derived mainly from phospholipids. The samples that contained nitrate curing salts contained more free fatty acids (FFA) (548 mg/100 g) than those that contained nitrite curing salts (478 mg/100 g) at the end of the fermentation step, as a consequence of having undergone a preripening stage, during which significant amounts of FFA are formed. However, at the end of the ripening process, although there is a significant increase of FFA levels in all the sausages, no significant differences between samples with nitrite and those with nitrate could be found. This result could have occurred if the oxidative effects of the samples with nitrate balanced the antioxidative properties of nitrite, such that, through different processes, similar concentrations of FFA are obtained at the end of ripening. Phospholipids (PL) and free fatty acids (FFA) are the lipid fractions that undergo the most important changes during ripening. PL are moderately degraded during the drying process, probably due to the combined effects of the drying temperature (10°C) and the presence of starters. However, this degradation does not differ significantly between the samples that contain nitrite and and those that contain nitrate in each control. Received: 23 July 1997 / Revised version: 8 October 1997     

Effect of nitrate and nitrite curing salts on lipolysis in dry sausages produced using a rapid fermentation process

 The effect of nitrite and nitrate curing salts on lipolysis in a typical non-smoked Spanish sausage (salchichón), manufactured using a rapid dry fermentation process, was studied. From the results obtained, one could deduce that nitrite and nitrate per se do not affect the endogenous hydrolysis of the lipids during the rapid fermentation process used to produce dry sausage. Polyunsaturated fatty acids (PUFA) are liberated in greater quantities than monounsaturated (MUFA) and saturated (SFA) ones, which suggests that they are derived mainly from phospholipids. The samples that contained nitrate curing salts contained more free fatty acids (FFA) (548 mg/100 g) than those that contained nitrite curing salts (478 mg/100 g) at the end of the fermentation step, as a consequence of having undergone a preripening stage, during which significant amounts of FFA are formed. However, at the end of the ripening process, although there is a significant increase of FFA levels in all the sausages, no significant differences between samples with nitrite and those with nitrate could be found. This result could have occurred if the oxidative effects of the samples with nitrate balanced the antioxidative properties of nitrite, such that, through different processes, similar concentrations of FFA are obtained at the end of ripening. Phospholipids (PL) and free fatty acids (FFA) are the lipid fractions that undergo the most important changes during ripening. PL are moderately degraded during the drying process, probably due to the combined effects of the drying temperature (10°C) and the presence of starters. However, this degradation does not differ significantly between the samples that contain nitrite and and those that contain nitrate in each control. Received: 23 July 1997 / Revised version: 8 October 1997     

Exposure estimates of nitrite and nitrate from consumption of cured meat products by the U.S. population

The dietary exposures of nitrite and nitrate from consumption of cured meat products were estimated for the U.S. population aged 2 years and older, and children aged 2 to 5 years, using both 2-day food consumption data from the publicly available combined 2009–2012 National Health and Nutrition Examination Survey (NHANES) and 10–14-day food consumption data from the 2009 and 2012 NPD Group, Inc. National Eating Trends-Nutrient Intake database (NPD NET-NID), and residual nitrite and nitrate levels in cured meat products available from the recent American Meat Institute Foundation/National Pork Board (AMIF/NPB) national market survey of the nitrite and nitrate levels in cured meat products in the U.S.A. The dietary exposure for consumers of cured meat products (eaters-only) was estimated at the mean and 90th percentile for three exposure scenarios: low exposure, average exposure, and high exposure, to account for the range in the amount of nitrite and nitrate in a given cured meat product category. In addition, a cumulative exposure that takes into account all cured meat product categories containing nitrite and nitrate was determined, and the relative percent contribution of each cured meat product category to the cumulative exposure was estimated. Cured, cooked sausages and whole-muscle brine-cured products were the two major contributing categories to dietary exposure of nitrite and nitrate for both U.S. population aged 2 years and older and children aged 2–5 years.     

Spectrophotometric Determination of Nitrite and Nitrate in Cured Meat by Sequential Injection Analysis

ABSTRACT: A robust, automated, labor-saving, accurate, and economical sequential injection system was developed for simultaneous determination of nitrite and nitrate in cured meat samples, based on the Shinn reaction. Nitrite is coupled and diazotized with sulfanilamide and N-(1-naphtyl)-ethylenediamine dihydrochloride, to form a colored compound that absorbs at 538 nm. Nitrate is previously in-line reduced to nitrite in a copperized cadmium column and measured as nitrite. The solutions' aspiration sequence, the influence of reagent and buffer concentrations, the manifold parameters, and the characteristics of the reducing column were studied. Nitrite and nitrate can be determined within the 0.030 to 1.22 of N-NO₂− and 0.034 to 3.95 mg/L of N-NO₃− ranges, respectively, at a sampling rate of 9/h. Detection limits of 9 μg/L of N for nitrite and 9 μg/L of N for nitrate were obtained, and the conversion rate of nitrate to nitrite was 100.6%± 1.8%. The results were in good agreement with those obtained by the reference methods, with relative standard deviations (r.s.d.) better than 3.70% for nitrites and 2.42% for nitrates.     

Determination of nitrate and nitrite in dairy samples by sequential injection using an in-line cadmium-reducing column

A sequential injection analysis (SIA) system for the spectrophotometric determination of nitrate in dairy samples was developed. A test portion was aspirated into a carrier solution containing ethylendiaminetetracetic acid (EDTA) and ammonium buffer, which flowed into a copperized cadmium reduction column installed in-line for the determination of the nitrate plus nitrite contents of samples. For the nitrite determination, another test portion of sample was aspirated and directly sent to the detector without reduction. Nitrate content was calculated from the difference between nitrate plus nitrite (expressed as nitrite) and nitrite content. The spectrophotometric determination is based on the Griess reaction. The proposed method was used to test several dairy samples (ultrapasteurized milk with 1.7% milk fat, whey, raw bovine milk and several cheese varieties). Results were statistically in good agreement with those provided by the reference procedure, with a detection limit of 0.15 mg L⁻¹. A sampling rate of 21 determinations per hour can be achieved with this procedure.     

Predictive modeling and probabilistic risk assessment of Clostridium perfringens in hamburgers and sandwiches

This study aimed to develop a mathematical model for the survival of Clostridium perfringens in hamburgers and sandwiches and to evaluate their microbial risk. The primary model was developed in hamburgers using 4 strains of C. perfringens at 5, 10, 15, 25 and 37 °C, and the kinetic parameters of the primary model were fitted well with the Weibull model (R²?≥?0.95). The secondary model was developed and validated in hamburgers and sandwiches using the Davey model, which was evaluated by B_f, A_f, and RMSE values within the acceptable range. A probabilistic risk model was developed and simulated using @Risk program to estimate the probability of infection (P_inf) of C. perfringens based on the data on prevalence (n?=?100), time, temperature, and consumption of hamburgers and sandwiches (150.00?±?20.96 g). Based on the simulation model, the mean C. perfringens exposure dose was 0.00976 CFU/g, and the estimated mean P_inf was 1.78?×?10^–13, which was very low in comparison with the current available data. The proposed model and the result can thus be useful to establish risk management options and microbial criteria for C. perfringens contamination in hamburgers and sandwiches.

     

Lupinus mutabilis: Composition,Uses, Toxicology,and Debittering

Lupinus mutabilis has protein (32.0–52.6 g/100 g dry weight) and lipid (13.0–24.6 g/100 g dry weight) contents similar to soya bean (Glycine max). The Ω3, Ω6, and Ω9 contents are 1.9–3.0, 26.5–39.6, and 41.2–56.2 g/100 g lipid, respectively. Lupins can be used to fortify the protein content of pasta, bread, biscuits, salads, hamburgers, sausages, and can substitute milk and soya bean. Specific lupin protein concentrates or isolates display protein solubility (>90%), water-absorption capacity (4.5 g/g dry weight), oil-absorption capacity (3.98 g/g), emulsifying capacity (2000 mL of oil/g), emulsifying stability (100%, 60 hours), foaming capacity (2083%), foaming stability (78.8%, 36 hours), and least gelation concentration (6%), which are of industrial interest. Lupins contain bitter alkaloids. Preliminary studies on their toxicity suggest as lethal acute dose for infants and children 10 mg/kg bw and for adults 25 mg/kg bw. However, alkaloids can also have medical use for their hypocholesterolemic, antiarrhythmic, and immunosuppressive activity. Bitter lupins can be detoxified by biological, chemical, or aqueous processes. The shortest debittering process requires one hour. This review presents the nutritional composition of lupins, their uses (as food, medicine, and functional protein isolates), toxicology, and debittering process scenarios. It critically evaluates the data, infers conclusions, and makes suggestions for future research.     

Time-dependent depletion of nitrite in pork/beef and chicken meat products and its effect on nitrite intake estimation

The food additive nitrite (E249, E250) is commonly used in meat curing as a food preservation method. Because of potential negative health effects of nitrite, its use is strictly regulated. In an earlier study we have shown that the calculated intake of nitrite in children can exceed the acceptable daily intake (ADI) when conversion from dietary nitrate to nitrite is included. This study examined time-dependent changes in nitrite levels in four Swedish meat products frequently eaten by children: pork/beef sausage, liver paté and two types of chicken sausage, and how the production process, storage and also boiling (e.g., simmering in salted water) and frying affect the initial added nitrite level. The results showed a steep decrease in nitrite level between the point of addition to the product and the first sampling of the product 24 h later. After this time, residual nitrite levels continued to decrease, but much more slowly, until the recommended use-by date. Interestingly, this continuing decrease in nitrite was much smaller in the chicken products than in the pork/beef products. In a pilot study on pork/beef sausage, we found no effects of boiling on residual nitrite levels, but frying decreased nitrite levels by 50%. In scenarios of time-dependent depletion of nitrite using the data obtained for sausages to represent all cured meat products and including conversion from dietary nitrate, calculated nitrite intake in 4-year-old children generally exceeded the ADI. Moreover, the actual intake of nitrite from cured meat is dependent on the type of meat source, with a higher residual nitrite levels in chicken products compared with pork/beef products. This may result in increased nitrite exposure among consumers shifting their consumption pattern of processed meats from red to white meat products.     

Effects of inorganic nitrate and nitrite consumption on cognitive function and cerebral blood flow: A systematic review and meta-analysis of randomized clinical trials

ABSTRACT

We conducted a systematic review and meta-analysis of randomized clinical trials examining the effect of inorganic nitrate or nitrite supplementation on cognitive function (CF) and cerebral blood flow (CBF). Two databases (PubMed, Embase) were searched for articles from inception until May 2017. Inclusion criteria were: randomized clinical trials; participants >18 years old; trials comparing a nitrate/nitrite intervention with a control. Thirteen and nine trials were included in the meta-analysis to assess CF and CBF, respectively. Random-effects models were used and the effect size described as standardized mean differences (SMDs). A total of 297 participants (median of 23 per trial) were included for CF; 163 participants (median of 16 per trial) were included for CBF. Nitrate/nitrite supplementation did not influence CF (SMD +0.06, 95% CI: -0.06, 0.18, P = 0.32) or CBF under resting (SMD +0.14, 95% CI: -0.13, 0.41, P = 0.31), or stimulated conditions (SMD + 0.23, 95% CI: -0.11, 0.56, P = 0.19). The meta-regression showed an inverse association between duration of the intervention and CBF (P = 0.02) but no influence of age, BMI or dose (P < 0.05). Nitrate and nitrite supplementation did not modify CBF or CF. Further trials employing larger samples sizes and interventions with longer duration are warranted.     

Evaluation of total aflatoxin,nitrate and nitrite levels in layer feed samples of companies producing their own feed in Edincik and Bandırma province of Turkey

Feed contamination by fungi can lead to nutrient losses and detrimental effects on animal health and production. The presence of nitrates and nitrites in food can be harmful to both people and animals. The aim of this study was to determine total aflatoxin, nitrate and nitrite levels in layer feed samples from companies producing their own feed in Edincik and Band?rma provinces in Turkey and to discuss the potential risk to animal health. The results of the analyses indicated that mean total aflatoxin (AFT) ranged from 0.4 to 36.8?µg?kg^?1 and from 0.45 to 47.0?µg?kg^?1 in the year 2007 and the year 2008 samples, respectively. It was determined that nitrate levels were 2.4–10 and 1.7–13?µg?kg^?1 and that nitrite levels were 0–2.4?µg?kg^?1 and 0–2.6?µg?kg^?1 in these years, respectively. The levels of total aflatoxin, nitrate and nitrite in the layer samples could not be considered a risk to poultry health and productivity.     

Commercial processed food may have endocrine-disrupting potential: soy-based ingredients making the difference

Processed and packaged food items as well as ready-to-eat snacks are neglected and poorly characterised sources of human exposure to endocrine-disrupting chemicals (EDCs). In this study we investigated the presence of xenoestrogens in commercially processed and packaged Finnish foods, arising from substances deliberately added or inadvertently contaminating the food, substances formed as a result of food processing, or substances leaching from food packaging materials. Samples were obtained in three separate batches of equivalent products from both a supermarket and a local representative of a global chain of hamburger restaurants and extracted by a solid-phase extraction method. Their endocrine-disrupting potential was determined by yeast bioluminescent assay, using two recombinant yeast strains Saccharomyces cerevisiae BMAEREluc/ERα and S. cerevisiae BMA64/luc. In this test system, the majority of samples (both foodstuffs and wrappers) analysed proved negative. However, all batches of industrially prepared hamburgers (but not those obtained from a hamburger restaurant) as well as pepper salami significantly induced luciferase activity in the BMAEREluc/ERα yeast strain indicating the presence of xenoestrogens, with estradiol equivalents of these products ranging from 0.2 to 443 pg g^–1. All three products contained soy-based ingredients, which apparently accounted for, or at least contributed to, their high estrogenic activity, since no signal in the assay was observed with extracts of the packaging material, while two different soy sauces tested yielded an intense signal (28 and 54 pg ml^–1 estradiol-equivalent). These findings imply that by and large chemicals arising in the processing or packaging of foodstuffs in Finland constitute an insignificant source of xenoestrogens to consumers. However, soy-derived ingredients in certain food items might render the entire products highly estrogenic. The estrogenic activity of soy is attributed to isoflavones whose health effects – though widely considered beneficial – are controversial. As hamburgers are a popular type of food among children, the findings are noteworthy and possibly of concern.     

A non-diazotization-coupling reaction-based colorimetric determination of nitrite in tap water and milk

A non-diazotization-coupling reaction-based colorimetric method was developed and validated for the determination of nitrite in tap water and milk samples. Under acidic condition, nitrite could selectively react with pyrrole, resulting in the emerging of a new absorption peak at 509 nm and a distinct color change from clear to red, with which the concentration of nitrite can be determined indirectly. Excellent linear range was achieved from 0.72 to 40.0 μmol L^?1 with a detection limit of 0.22 μmol L^?1. The detection limit was lower than or comparable to most of the recently published methods. The experimental conditions were optimized, and effects of coexisting substances were evaluated, and the results showed excellent priority since a certain amount of other anions, including SO₃ ^?, SeO₃ ^? and other acid radicals, would not interfere with the measurement. We highlighted the simplicity and efficiency of this method as no diazotization-coupling procedure and toxic aniline were involved. Determination of nitrite in tap water and milk samples was performed.     

Quantification of Nitrite/Nitrate in Food Stuff Samples Using 2-Aminobenzoic Acid as a New Amine in Diazocoupling Reaction

2-Aminobenzoic acid has been used as an amine in diazocoupling reaction to form an azo dye in the quantification of nitrite/nitrate at trace level. The formed azo dye has an absorption maximum at 550 nm in aqueous phase, and the resulted dye can be extracted into organic solvent to lower the detection limit. The method obeys Beer's law in the concentration range 0–10 μg of nitrite in 25 ml of aqueous solution with a molar absorptivity of 3.6 × 10³ L mol⁻¹ cm⁻¹ and 0–2 μg of nitrite in 5 ml of organic phase. The detection limit of the dye has been found to be 0.056 μg ml⁻¹. Nitrate is determined by reducing it to nitrite after passing through a copperized cadmium reductor column. The effect of interfering ions on the determination of nitrite/nitrate has been described. The developed method has been applied to determine the nitrite/nitrate trace level in vegetable, fruit juice, and milk powder samples.     

The oral nitrate and nitrite intake in The Netherlands: evaluation of the results obtained by HPIC analysis of duplicate 24-hour diet samples collected in 1994.

In spring and autumn of 1994 duplicates of 24-h diets were collected from 123 respondents. One of the goals of this study was to determine the amount of nitrite and nitrate in the duplicates of 24-h diets to establish the oral daily intake of these analytes. For this purpose an HPIC/UV method for the determination of nitrate and nitrite in duplicate diets was developed and validated. The sample preparation procedure was derived from the in-house method used for the determination of nitrate and nitrite in human blood plasma. The sample is diluted with water, deproteinized with Carrez reagent, followed by chromatographic clean-up on an SPE C18-column. Both the nitrate and the nitrite results are quantitative. The recovery for nitrite was on average 104% (n = 21, spiking levels: 0.84-95 mg/kg) and for nitrate on average 103% (N = 21, spiking levels: 1.8-404 mg/kg). Samples of duplicates of 24-h diets were analysed according to the method developed. The median intake of nitrite calculated from the samples collected in spring 1994 was 0.6 mg/person day (range < 0.1-6.1 mg/person/day). For the samples collected in autumn 1994 these figures were < 0.2 mg/person/day (range < 0.1-16 mg/person/day). The mean intake of nitrate was 73 mg/person/day (range 7-322 mg/person/day) in spring 1994 and 87 mg/person/day (range 1-310 mg/person/day) in autumn 1994. The overall mean intake of nitrate in 1994 was 80 mg/person/day. The daily intake for nitrate was higher than that found in the duplicate diet study carried out in 1984/1985, when an average daily intake of 52 mg/person was measured. The intake of nitrite was also higher than found in the duplicate diets collected in 1984/1985. The findings of the study are discussed in the context of the ADI for nitrate and nitrite as well as the outcome of other recent European intake studies.     

Metabolism of nitrate in fermented meats: the characteristic feature of a specific group of fermented foods

Within the universe of food fermentation processes the multi-purpose use of nitrate and/or nitrite is a unique characteristic of meat fermentations. These curing agents play a decisive role in obtaining the specific sensory properties, stability and hygienic safety of products such as fermented sausages, ham and, more recently, emulsion type of sausages. The use of nitrate is the traditional method in curing processes and requires its reduction to reactive nitrite. Thus, nitrate reduction is the key event that is exclusively performed by microorganisms. Under controlled fermentation conditions starter cultures are used that contain staphylococci and/or Kocuria varians, which in addition to strongly affecting sensory properties exhibit efficient nitrate reductase activity. To obtain clean label products some plant sources of nitrate have been in use. When producing thermally treated sausages (e.g. of emulsion type), starter cultures are used that form nitrite before cooking takes place. Staphylococci reduce nitrite to ammonia after nitrate has been consumed. K. varians is devoid of nitrite reductase activity. Nitrate and nitrite reductases are also present in certain strains of lactobacilli. It was shown that their application as starter cultures warrants efficient activity in sausages made with either nitrate or nitrite. NO is formed from nitrite in numerous chemical reactions among which disproportionation and reaction with reductants either added or endogenous in meat are of practical importance. Numerous nitrosation and nitrosylation reactions take place in the meat matrix among which the formation of nitrosomyoglobin is of major sensory importance.Safety considerations in meat fermentation relate to the safe nature of the starter organisms and to the use of nitrate/nitrite. Staphylococci (“micrococci”) in fermented meat have a long tradition in food use but have not received the QPS status from the EFSA. They require, therefore, thorough assessment with regard to toxigenicity and pathogenicity determinants as well as presence of transferable antibiotic resistance. Nitrate and nitrite are still considered basically undesired in food. The main objections are based on their potential to form nitrosamines with carcinogenic potential. In view of new results from intensive research of NO, potential risks are opposed by positive effects on human health.     

The sensory quality of dry fermented sausages as affected by fermentation stage and curing agents

The effects on the quality of dry fermented sausages of applying either a slow or rapid fermentation stage, and the addition of either nitrate or nitrite was studied. In the slow fermentation process, TBARS were higher in the batch made with nitrite than in the batch containing nitrate. For rapid fermentation, both batches, with added nitrate and nitrite, presented intermediate TBARS levels. Volatile compounds coming from lipid oxidation and microbial lipid β-oxidation were more abundant (p < 0.05) in the samples submitted to a rapid fermentation stage, whilst compounds coming from amino acid catabolism and carbohydrate fermentation were higher (p < 0.05) in samples subjected to a slow fermentation stage. A significant preference (p < 0.05) was shown during sensory analysis for the batch made with nitrate and submitted to the slow fermentation process in aroma, taste and overall quality, whilst no differences in sensory analysis were detected among batches in the rapid fermentation process. Therefore, the use of nitrate is only justified in slow fermented processes due to its positive effect on the sensory quality of fermented sausages.