Evaluation of the influence of proline, hydroxyproline or pyrrolidine in the presence of sodium nitrite on N-nitrosamine formation when heating cured meat

N-Nitrosamines: a potential hazard in processed meat products

Nitrite, nitrate, and their salts are added to processed meat products to improve color, flavor, and shelf life and to lower the microbial burden. N-Nitrosamine compounds are formed when nitrosing agents (such as secondary nitrosamines) in meat products interact with nitrites and nitrates that have been added to the meat. With the consumption of such meat products, nitrosation reactions occur in the human body and N-nitrosamine formation occurs in the gastrointestinal tract. Despite the benefits nitrites and nitrates have on food, their tendency to create nitrosamines and an increase in the body's nitrous amine load presents health risks. The inclusion of nitrosamine compounds in possible and probable carcinogen classes according to the International Agency for Research on Cancer requires a re-examination of the literature review on processed meat products. This article evaluates the connections between various cancer types and nitrosamines found in processed meat products. © 2023 Society of Chemical Industry.

Preparation of metal-organic framework @molecularly imprinted polymers for extracting N-nitrosamines in salted vegetables

In this paper, the novel metal-organic framework @molecularly imprinted polymers were prepared and applied in extracting N-nitrosamines from salted vegetables. The imprinted polymers were coated on the surface of MIL-101 using multi-dummy template molecules (5-nonanol, benzhydrol and N-formylpyrrolidine). The characterization and adsorbing experiments showed that the hybrid imprinted polymers presented spherical particles with typically core-shell structure, and exhibited high adsorption capacity (maximum capacity: 46.85 mg/g) and fast equilibrium rate (only 5 min) for N-nitrosamines. Various parameters (sample loading solvent, pH, washing solvent, elution solvent and elution volume) affecting solid-phase extraction were optimized. Under the optimum conditions, the solid-phase extraction process based on the hybrid polymers combined with high performance liquid chromatography-ultraviolet detection method was established and applied to analyze N-nitrosamines in different salted vegetables. The results showed that the developed method produced the linear relationship between the peak areas versus the N-nitrosamines concentrations of 0.2-10 µg/g with limit of detections from 20.6 to 76.1 ng/g. The spiked recovery of N-nitrosamines in the salted vegetable samples was in the range of 66-100.5 % with relative standard deviation from 0.1 to 3.4 %. Those results demonstrated that the established method was sensitive and efficient for directly enriching and analyzing trace N-nitrosamines in salted vegetables.

Natural Occurrence of Nitrite-Related Compounds in Malt and Beer

Despite sufficient control of volatile N-nitrosamines in foods and beverages, little attention remained on nonvolatile nitroso compounds, which are mostly unknown and relative to nitrite reactions. In a recent study, new compounds related to reactions of nitrite in beer were pyruvic acid oxime, 4-nitrosophenol, 4-cyanophenol, N-nitrosoproline ethyl ester, nitrosoguaiacol, and 2-methoxy-5-nitrophenol, as well as the already known N-nitrosoproline. The present study is intended to observe their natural occurrence in commercial beers and malts. All 22 nitrite-related products (N-products) were monitored in almost 200 samples of beers and malts. As many as 17 N-products were detected in malts, and all 22 N-products were found in beers. The hierarchical clustering grouped samples based on similarities of detected N-products by frequency of their appearance and level of response. Between N-products and N-nitrosodimethylamine concentrations in malts, only moderate Pearson correlations were found. The same applied to N-product correlations with the apparent total nitroso compound determination in beers.

Risk assessment of N-nitrosamines in food

EFSA was asked for a scientific opinion on the risks to public health related to the presence of N-nitrosamines (N-NAs) in food. The risk assessment was confined to those 10 carcinogenic N-NAs occurring in food (TCNAs), i.e. NDMA, NMEA, NDEA, NDPA, NDBA, NMA, NSAR, NMOR, NPIP and NPYR. N-NAs are genotoxic and induce liver tumours in rodents. The in vivo data available to derive potency factors are limited, and therefore, equal potency of TCNAs was assumed. The lower confidence limit of the benchmark dose at 10% (BMDL10) was 10 μg/kg body weight (bw) per day, derived from the incidence of rat liver tumours (benign and malignant) induced by NDEA and used in a margin of exposure (MOE) approach. Analytical results on the occurrence of N-NAs were extracted from the EFSA occurrence database (n = 2,817) and the literature (n = 4,003). Occurrence data were available for five food categories across TCNAs. Dietary exposure was assessed for two scenarios, excluding (scenario 1) and including (scenario 2) cooked unprocessed meat and fish. TCNAs exposure ranged from 0 to 208.9 ng/kg bw per day across surveys, age groups and scenarios. 'Meat and meat products' is the main food category contributing to TCNA exposure. MOEs ranged from 3,337 to 48 at the P95 exposure excluding some infant surveys with P95 exposure equal to zero. Two major uncertainties were (i) the high number of left censored data and (ii) the lack of data on important food categories. The CONTAM Panel concluded that the MOE for TCNAs at the P95 exposure is highly likely (98-100% certain) to be less than 10,000 for all age groups, which raises a health concern.

The occurrence of volatile N-nitrosamines in heat-treated sucuk in relation to pH, aw and residual nitrite

In this study, the occurrence of volatile nitrosamines were investigated in heat-treated sucuk, a kind of semi-dry fermented sausage. The pH, a_w and residual nitrite of the samples were also determined. In addition, a principal component analysis (PCA) was also performed in order to elucidate the relationship between nitrosamine and these variables. Significant differences between brands were found in terms of NDMA (N- Nitrosodimethylamine), NPYR (N-Nitrosopyrolidine) and NPIP (N-Nitrosopiperidine) (p < 0.05). NDMA and NPYR varied from 1.71 to 3.57 µg/kg and 1.65 to 7.29 µg/kg, respectively. Higher levels were found for NPIP (5.19 to 16.40 µg/kg). NDEA (N-Nitrosodiethylamine) and NDBA (N- Nitrosodibutylamine) were not found in any of the heat-treated sucuk samples. The residual nitrite content was under 10 mg/kg in all samples. The a_w and pH values varied between 0.913 and 0.940 and between 4.28 and 5.47, respectively. In PC1 explaining 72% of the variance, NDMA and NPYR were placed on the negative side, NPIP on the positive side. Residual nitrite and a_w were more effective for NPIP, while pH was an important parameter for NDMA and NPYR.

Nitrite, biogenic amines and volatile N-nitrosamines in commercial Chinese traditional fermented fish products

To examine the safety of Chinese traditional fermented fish products (CTFPs) available on the Chinese market, nitrite, nitrate, biogenic amines (BAs) and volatile N-nitrosamines (VNAs) content in 33 commercial CTFPs from different provinces was investigated. The mean content of nitrite and nitrate wase 0.63 and 749.5 mg/kg, respectively. Concerning the occurrence of BAs, the accumulation in all CTFPs samples remained at low levels, whereas only in one sample from Guangxi the histamine content exceeded the critical level (50 mg/kg). In addition, six types of VNAs, including N-nitrosodimethylamine (NDMA), N-nitrosoethylmethylamine, N-nitrosopiperidine, N-nitrosopyrrolidine, N-nitrosomorpholine and N-nitrosodiphenylamine, were detected in a high number of samples. The NDMA content in 36.4% of the samples and the total VNAs content in about 63.6% of the samples were unacceptable. Principal component analysis indicated that the accumulation of NDMA and total VNAs was closely related with the content of histamine, tyramine and nitrate.

Changes in moisture, colour, residual nitrites and N-nitrosamine accumulation of bacon induced by nitrite levels and dry-frying temperatures

The effects of different nitrite levels (50, 100, and 150 mg/kg meat) and dry-frying temperatures (100, 150, 200 and 250 °C) on the moisture movement, colour, sensory variables and residual nitrite and N-nitrosamine levels in smoked bacon were investigated. Increasing the dry-frying temperatures significantly increased the cooking loss and decreased the moisture content (P < 0.05). The bacon L*-values showed an increasing trend at first and then decreased, with the highest value of the bacon with 150 mg/kg nitrite was obtained at 100 °C and 150 °C. In addition, a*-values were significantly affected by the nitrite level and dry-frying temperature (P < 0.05), with the highest value of the bacon samples with 100 and 150 mg/kg nitrite observed at 250 °C. The residual nitrite content level initially increased (from unheated control to 150 °C) and then decreased (from 150 to 250 °C) sharply with increasing dry-frying temperatures in the bacon samples with the same sodium nitrite levels. N-methyl-N-nitrosoaniline (NMPhA) and N-nitrosomorpholine (NMOR) were measured in a number of smoked bacon samples, and a significant positive correlation (R² = 0.772) was found for N-nitrosamines (NA) contents and nitrite levels (P < 0.05). The maximum levels of NMPhA and NMOR were detected when the bacon with 150 mg/kg sodium nitrite was pan-fried at 200 °C and 150 °C, respectively.

The Possibility of Reduction of Synthetic Preservative E 250 in Canned Pork

The purpose of this study was to determine the possibility of reducing the amount of NaNO2 added to canned pork during 180 days of storage. In this study, three variants of canned pork were prepared by adding different amounts of sodium nitrite: N (100 mg/kg), NH (50 mg/kg), and NF (no nitrite). The antioxidant capacity, amount of secondary products of lipid oxidation, color intensity, and pH were analyzed after one, 60, 90, and 180 days of storage where sensory properties, water activity (aw), selected pathogenic bacteria, nitrate and nitrite residues, N-nitrosamines (NA), and cholesterol were analyzed after 1 and 180 days of storage. The redness parameter of the nitrite-free canned meat was found to be significantly lower (about 6.4) than that of the products containing sodium nitrite (N: 10.49 and NH: 9.89). During the storage period C. perfringens, L. monocytogenes, and Salmonella were detected in the products. It is not possible to completely eliminate nitrite from the canned pork production process without deteriorating the color, antioxidant properties, sensory characteristics, and health safety. However, the level of hazard chemicals such as NA, nitrate and nitrite residues can be limited by decreasing the amount of nitrite addition to 50 mg/kg. The free-radical scavenging ability for the sample with 50 mg/kg of sodium nitrite was observed to be poor, so its fortification with plant material rich in various polyphenolic substances may be necessary.

Progress in the pretreatment and analysis of N-nitrosamines: an update since 2010

As highly toxic substances, N-nitrosamines (NAs) have been proved to cause carcinogenesis and mutagenesis in humans. Therefore, to carefully monitor safety and preserve human health, the development of rapid, accurate, and high-sensitivity determination methods of NAs is of substantial importance. This review provides a current-status comprehensive summary of the pretreatment and determination methods of NAs in various samples since 2010. Common pretreatment methods that have been used to extract and purify targets include solid-phase extraction, liquid-liquid extraction and various microextraction methods, such as solid-phase microextraction and liquid-phase microextraction, among others. Determination methods include liquid chromatography, gas chromatography, supercritical fluid chromatography and electrochemical methods, among others. In addition, we discuss and compare the advantages and disadvantages of various pretreatment and analytical methods and examine the prospects in this area.

Nitrosamine formation in a semi-dry fermented sausage: Effects of nitrite, ascorbate and starter culture and role of cooking

In this study, effects of ingoing nitrite level (0, 50, 100 and 150 mg/kg), use of sodium ascorbate, addition of starter culture (Lactobacillus plantarum GM77 + Staphylococcus xylosus GM92) and cooking level (control, medium, medium well, well done and very well done) on nitrosamine formation in heat-treated sucuk, a type of semi-dry fermented sausage, were investigated. The use of ascorbate had no significant effect on NDMA (N-Nitrosodimethylamine) and NPIP (N-Nitrosopiperidine) contents in the presence of starter culture. A higher NPYR (N- Nitrosopyrrolidine) content was detected in the group with starter culture at 150 mg/kg nitrite level in comparison to the group without starter culture. Cooking level affected all identified nitrosamines very significantly. Ingoing nitrite level × cooking level interaction was only effective on NPIP and advanced cooking levels (well done and very well done) at higher ingoing nitrite levels (100 and 150 mg/kg) resulted in significant increases in NPIP content.

Re-evaluation of sodium nitrate (E 251) and potassium nitrate (E 252) as food additives

The Panel on Food Additives and Nutrient Sources added to Food (ANS) provided a scientific opinion re-evaluating the safety of sodium nitrate (E 251) and potassium nitrate (E 252) when used as food additives. The current acceptable daily intakes (ADIs) for nitrate of 3.7 mg/kg body weight (bw) per day were established by the SCF (1997) and JECFA (2002). The available data did not indicate genotoxic potential for sodium and potassium nitrate. The carcinogenicity studies in mice and rats were negative. The Panel considered the derivation of an ADI for nitrate based on the formation of methaemoglobin, following the conversion of nitrate, excreted in the saliva, to nitrite. However, there were large variations in the data on the nitrate-to-nitrite conversion in the saliva in humans. Therefore, the Panel considered that it was not possible to derive a single value of the ADI from the available data. The Panel noticed that even using the highest nitrate-to-nitrite conversion factor the methaemoglobin levels produced due to nitrite obtained from this conversion would not be clinically significant and would result to a theoretically estimated endogenous N-nitroso compounds (ENOC) production at levels which would be of low concern. Hence, and despite the uncertainty associated with the ADI established by the SCF, the Panel concluded that currently there was insufficient evidence to withdraw this ADI. The exposure to nitrate solely from its use as a food additive was estimated to be less than 5% of the overall exposure to nitrate in food based on a refined estimated exposure scenario. This exposure did not exceed the current ADI (SCF, 1997). However, if all sources of exposure to dietary nitrate are considered (food additive, natural presence and contamination), the ADI would be exceeded for all age groups at the mean and the highest exposure.

Re-evaluation of potassium nitrite (E 249) and sodium nitrite (E 250) as food additives

The Panel on Food Additives and Nutrient Sources added to Food (ANS) provided a scientific opinion re-evaluating the safety of potassium nitrite (E 249) and sodium nitrite (E 250) when used as food additives. The ADIs established by the SCF (1997) and by JECFA (2002) for nitrite were 0-0.06 and 0-0.07 mg/kg bw per day, respectively. The available information did not indicate in vivo genotoxic potential for sodium and potassium nitrite. Overall, an ADI for nitrite per se could be derived from the available repeated dose toxicity studies in animals, also considering the negative carcinogenicity results. The Panel concluded that an increased methaemoglobin level, observed in human and animals, was a relevant effect for the derivation of the ADI. The Panel, using a BMD approach, derived an ADI of 0.07 mg nitrite ion/kg bw per day. The exposure to nitrite resulting from its use as food additive did not exceed this ADI for the general population, except for a slight exceedance in children at the highest percentile. The Panel assessed the endogenous formation of nitrosamines from nitrites based on the theoretical calculation of the NDMA produced upon ingestion of nitrites at the ADI and estimated a MoE > 10,000. The Panel estimated the MoE to exogenous nitrosamines in meat products to be < 10,000 in all age groups at high level exposure. Based on the results of a systematic review, it was not possible to clearly discern nitrosamines produced from the nitrite added at the authorised levels, from those found in the food matrix without addition of external nitrite. In epidemiological studies there was some evidence to link (i) dietary nitrite and gastric cancers and (ii) the combination of nitrite plus nitrate from processed meat and colorectal cancers. There was evidence to link preformed NDMA and colorectal cancers.

Determination of N-nitrosamines by automated dispersive liquid-liquid microextraction integrated with gas chromatography and mass spectrometry

An automated dispersive liquid-liquid microextraction integrated with gas chromatography and mass spectrometric procedure was developed for the determination of three N-nitrosamines (N-nitroso-di-n-propylamine, N-nitrosopiperidine, and N-nitroso di-n-butylamine) in water samples. Response surface methodology was employed to optimize relevant extraction parameters including extraction time, dispersive solvent volume, water sample pH, sodium chloride concentration, and agitation (stirring) speed. The optimal dispersive liquid-liquid microextraction conditions were 28 min of extraction time, 33 μL of methanol as dispersive solvent, 722 rotations per minute of agitation speed, 23% w/v sodium chloride concentration, and pH of 10.5. Under these conditions, good linearity for the analytes in the range from 0.1 to 100 μg/L with coefficients of determination (r(2) ) from 0.988 to 0.998 were obtained. The limits of detection based on a signal-to-noise ratio of 3 were between 5.7 and 124 ng/L with corresponding relative standard deviations from 3.4 to 5.9% (n = 4). The relative recoveries of N-nitroso-di-n-propylamine, N-nitrosopiperidine, and N-nitroso di-n-butylamine from spiked groundwater and tap water samples at concentrations of 2 μg/L of each analyte (mean ± standard deviation, n = 3) were (93.9 ± 8.7), (90.6 ± 10.7), and (103.7 ± 8.0)%, respectively. The method was applied to determine the N-nitrosamines in water samples of different complexities, such as tap water, and groundwater, before and after treatment, in a local water treatment plant.

The occurrence of N-nitrosamines, residual nitrite and biogenic amines in commercial dry fermented sausages and evaluation of their occasional relation

Regarding food borne intoxications, the accumulation of biogenic amines must be avoided in all kinds of food products. Moreover, biogenic amines can function as precursors for the formation of carcinogenic N-nitrosamines when nitrite is present. To estimate the food safety of the dry fermented sausages available on the Belgian market, a screening of the residual sodium nitrite and nitrate contents, biogenic amines and volatile N-nitrosamine concentrations was performed on 101 samples. The median concentrations of residual NaNO2 and NaNO3 were each individually lower than 20mg/kg. In general, the biogenic amine accumulation remained low at the end of shelf life. Only in one product the amounts of cadaverine and putrescine reached intoxicating levels. Concerning the occurrence of N-nitrosamines, only N-nitrosopiperidine and N-nitrosomorpholine were detected in a high number of samples (resp. 22% and 28%). No correlation between the presence of N-nitrosamines and the biogenic amines content was observed. Although the N-nitrosamines could not been linked to specific product categories, the occurrence of N-nitrosopiperidine could probably be attributed to the use of pepper.