Rubber Nettings Research Articles

Ultrasound Assisted Extraction Approach to Test the Effect of Elastic Rubber Nettings on the N-Nitrosamines Content of Ham Meat Samples.

Nitrosamines (NAs), which are catalogued as carcinogenic compounds, may be present in meat products due to the conversion of nitrites and as result of migration from elastic rubber nettings used. A method based on ultrasonic assisted extraction coupled with dispersive liquid–liquid microextraction as sample treatment and gas chromatography-mass spectrometry as separation and detection technique was proposed for the determination of twelve NAs in cooked ham samples. The method was validated by evaluating linearity (0.5–1000 ng g−1), matrix effect, sensitivity (detection limits were between 0.15 and 1.4 ng g−1) and precision, which was below 12%. Five NAs were found in the samples with levels ranging from not quantifiable to 40 ng g−1. The effect of the elastic rubber nettings on the nitrosamine content of meat was evaluated by comparing the levels found in products made with several plastics or thread in the presence of additives.

Identification of extractable substances from rubber nettings used to package meat products

Ten meat nettings were sampled from four different suppliers in the Netherlands. These meat nettings consisted both of natural rubber and of vegetable fibres. Nitrosamines were extractable up to 2 mg kg-1 netting, the nitrosamine being N -nitrosodibenzylamine. The nitrosatable substances found were precursors of N -nitrosodimethylamine and N -nitrosodibenzylamine and were extracted up to 0.4 mg kg-1 nettings. Considering the ratio of meat netting and foodstuff, the extractable amount of nitrosamines and nitrosatable substances does not raise concern for public health. The meat nettings were also screened for other potential migrants. Extractable amounts of several alkanes, alkenes, acids, antioxidants, plasticizers and sterols were found. Several of these extracted substances are not allowed in the Netherlands, although some are authorized in other countries. Several substances, however, have not been evaluated for use in food-contact materials and therefore the possible risk to public health is unknown.

Nitrosamine Formation in Processed Hams as Related to Reformulated Elastic Rubber Netting

ABSTRACTA survey of boneless hams processed in elastic rubber nettings showed that 32 of 59 contained over 100 ppb N‐nitrosodibenzylamine (NDBzA) on the surface. These findings demonstrated the need to reduce the nitrosamine content. Nettings made with rubber thread reformulated with zinc diisobutyldithiocarbamate vulcanizing agent were evaluated for their effect on reducing the nitrosamine content. The N‐nitrosodiisobutylamine (NDiBA) values ranged from 4.6 to 33.5 ppb (mean 16.1 ppb) compared to 52.3 to 739.9 ppb NDBzA(mean 191.2 ppb) in the control hams. No detectable nitrosamines were found in the unused experimental nettings. The low amounts of NDiBA found on the outer surface of these hams suggested that the use of these new nettings would provide a beneficial alternative to nettings currently in use.

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.

Nitrosamine Formation and Penetration in Hams Processed in Elastic Rubber Nettings: N-Nitrosodibutylamine and N-Nitrosodibenzylamine

N-Nitrosodibutylamine (NDBA) was previously detected on the outer surface of commercial boneless hams processed in elastic rubber nettings. More recently, N-nitrosodibenzylamine (NDBzA) has been reported in boneless ham products, reflecting a change in the formulation of the rubber used in the manufacture of the nettings. As a result, a study was carried out on the penetration of these two nitrosamines and their secondary amine precursors into hams. Most of the NDBA and NDBzA was detected in the first 0.5 in. from the surface, with a marked drop off (67-75%) after the first 0.25 in., indicating that the nitrosamines were formed at the product surface in contact with the elastic rubber netting. Detectable levels of both nitrosamines were found at a depth of 1.25 in. A gradual rather than a sharp decline was noted for both amines, DBA and DBzA, after the first 0.25 in. A comparison of NDBzA values on the outer surface of the ham versus a center slice was also made.

Supercritical Fluid Extraction of N-Nitrosamines in Hams Processed in Elastic Rubber Nettings

A method for analysing N-nitrosamines in hams processed in elastic rubber nettings by supercritical fluid extraction (SFE) is described. The study was carried out with the prototype of a commercial extractor with a silica gel adsorption cartridge integrally attached to the variable restrictor. The SFE method was compared with a solid-phase extraction procedure currently used for ham analysis. Both methods used the same gas chromatographic-chemiluminescence detection conditions. No significant difference (p < 0.05) was found between results obtained with the 2 methods. Repeatability standard deviation of the SFE method was 1.7 ppb, with a coefficient of variation (CV) of 2.7%, compared with 2.2 ppb, with a CV of 3.5%, for solid-phase extraction. SFE permits minimal use of solvent and more rapid analysis of nitrosamines.

Thermal decomposition of the rubber vulcanization agent, zinc dibenzyldithiocarbamate, and its potential role in nitrosamine formation in hams processed in elastic nettings

The thermal decomposition of zinc dibenzyldithiocarbamate (ZnDBzDTC), a compound used in the formulation of rubber and a possible precursor for N-nitrosodibenzylamine (NDBzA), was studied by a variety of thermal and spectroscopic techniques. At 326 o C, the decomposition temperature of the dithiocarbamate, carbon disulfide and dibenzylamine were the principal products formed. Smaller amounts of toluene, benzyl isothiocyanate, N,N,N'-tribenzylthiourea, and benzylbenzylidene were identified. The amount of dibenzylamine (DBzA) formed by the thermal decomposition of ZnDBzDTC may have a limited role in the formation of NDBzA in hams processed in elastic rubber nettings

Kinetic study on the nitrosation of dibenzylamine in a model system

A kinetic study of the formation of N-nitrosodibenzylamine (NDBzA), from the nitrosation of dibenzylamine (DBzA) by sodium nitrite, was performed in a model system under conditions (temperature, pH) that are similar to those encountered in the industrial production of hams processed in elastic rubber nettings. The nitrosation reaction was carried out in a KH 2PO 4 buffer (0.5 m) at pH 5.8 and at a temperature of 69 C. Since DBzA is insoluble in an aqueous buffer system, a non-ionic surfactant. Tween 20, was used as a solubilizing agent. The nitrosation reaction exhibited first-order kinetics with respect to DBzA and second-order kinetics with respect to nitrite. The calculated rate constant was 4.7 ± 0.5 m −2/ min. The pH profile of NDBzA formation was also determined. The optimal pH of NDBzA formation, 3.12, was close to the pK a of nitrous acid (HNO 2, pK a = 3.1).

Gas Chromatographic/Thermal Energy Analyzer Method for N-Nitrosodibenzylamine in Hams Processed in Elastic Rubber Netting

We previously described a solid-phase extraction (SPE) procedure for determining volatile nitrosamines in hams processed in elastic rubber nettings. This same procedure was found to successfully isolate N-nitrosodibenzylamine (NDBzA), a semivolatile nitrosamine. This nitrosamine may form as a result of the reformulated rubber now used in nettings. Reformulation became necessary because of the reported presence of N-nitrosodibutylamine in both the old nettings and on the exterior portion of commercial hams. After SPE, NDBzA was quantitated by using a gas chromatographic (GC) system interfaced to a nitrosamine-specific chemiluminescence detector [thermal energy analyzer (TEA)]. The GC system was equipped with a heated interface external to the TEA furnace to facilitate quantitation of NDBzA. With separation on a packed column, the method can be used to analyze 10 volatile nitrosamines and NDBzA. Repeatability of the method for NDBzA was found to be 2.1 ppb, and the coefficient of variation (CV) was 10.6%. Analysis of 18 commercial hams from 9 different producers, purchased from local retailers, indicated that 12 were positive for NDBzA (range, 2.6-128.5 ppb). NDBzA was confirmed by GC/mass spectrometry.

N‐Nitrosodibutylamine and other Volatile Nitrosamines in Cured Meat Packaged in Rubber Nettings

ABSTRACTResults from investigations of N‐nitroso‐n‐dibutylamine (NDBA) in cured meat are compared from investigations in Denmark, the USA and Canada. NDBA was detected in very few samples and in quantities that were very low. Cured meats packaged in plastic wrappings or cotton nettings did not contain any NDBA. All cured meat packaged in elastic rubber nettings on the Danish market cannot contain more than 0.5 ppb NDBA.

Nitrosamines in cured pork products packaged in elastic rubber nettings: An update

Previous research has shown that traces to fairly high levels of certain N-nitrosamines can form in cured pork products packaged in elastic rubber nettings. The N-nitrosamines are formed due to the interaction of nitrite additive in the meat and amine additives in the rubber that are used as accelerators in the curing of rubber. This paper briefly reviews earlier findings and presents some recent results. Of twenty samples of such pork products analyzed, one was negative, six contained 12–32 μg/kg levels of N-nitrosodibenzylamine (NDBZA) but no N-nitrosodi- n-butylamine (NDBA), and the remaining samples contained appreciable levels of both the compounds (NDBA up to 48 μg/kg and NDBZA up to 520 μg/kg). These results suggest that the problem of N-nitrosamine formation in these products is yet to be resolved.

Solid-Phase Extraction Method for Volatile N-Nitrosamines in Hams Processed with Elastic Rubber Netting

Abstract A method was developed for the determination of volatile N-nitrosamines in hams processed In elastic rubber nettings. The method was based on a modification of a solid-phase extraction (SPE) procedure used in the past to determine selected nitrosamines in different types of cured meat products. The nitrosamines detected in ham most likely originate from the amine precursors in rubber and from the nitrite commonly used in the meat curing process. The method was compared with 2 established procedures for N-nitrosodibutylamine (NDBA) analysis in cured meat products: the mineral oil distillation procedure (MOD) and the low temperature vacuum distillation procedure (LTVD). All 3 methods used the same gas chromatographic/chemlluminescent detection conditions and system. No significant difference was found between the MOD and LTVD methods. These methods were found to yield significantly higher NDBA levels than the SPE procedure. When 2,6-dimethylmorpholine was added to the sample before analysis in the MOD and LTVD procedures, artifactual nitrosamines were formed. No artifactual formation was noted in the SPE method. We propose that the new SPE method replace the current methods being used for analysis of netted, cured meat products.

Evaluation of genotoxicity of N-nitrosodibenzylamine in Chinese hamster V79 cells and in Salmonella

Health concerns have arisen due to the formation of N-nitrosodibenzylamine (NDBzA; CAS No. 5336-53-8) in pork processed in a new type of rubber netting. In view of the potent carcinogenicity of related nitrosamines (e.g. N-nitroso- n-dibutylamine and N-nitrosodiethylamine), NDBzA was evaluated for genotoxicity in vitro in both Chinese hamster V79 cells and in Salmonella. In V79 cells, concentrations up to 25 μg/ml were tested with and without activation by rat or hamster hepatocytes. Significant elevation of SCE frequency was seen only at 25 μg/ml in the presence of uninduced hamster hepatocytes. Mutation to 6-thioguanine resistance was observed at 25μg/ml, in the absence of hepatocytes and in the presence of induced (Aroclor 1254) or uniduced hamster hepatocytes, but not with rat hepatocytes. With uninduced rat hepatocytes, a small but significant ( p < 0.05) increase in the mutation frequency was seen with 10μg/ml NDBzA. In the Salmonella assay, using a pre-incubation protocol and concentrations up to 1000 μg/ml. NDBzA was negative in strain TA98, and in TA100 with rat S9, but was positive at the highest dose in TA100 with hamster S9, and more strongly with Aroclor 1254-induced hamster S9. When activated by uninduced rat or hamster hepatocytes, as opposed to S9, NDBzA was negative with all tester strains. Hamster hepatocytes activated more than rat in the V79 studies, and hamster S9 was more strongly activating in the Salmonella assay. These results indicate NDBzA is weakly mutagenic to both Salmonella and V79 cells.

Further Studies on the Formation of Nitrosamines in Cured Pork Products Packaged in Elastic Rubber Nettings

ABSTRACTTraces of N‐nitrosodi‐n‐butylamine (NDBA) and N‐nitrosodiethylamine (NDEA) can form in cured pork products packaged in elastic rubber nettings due to the interaction of nitrite in meat and amines in the rubber. Studies were carried out to determine whether taking nettings off immediately after processing or placing a layer of collagen as a barrier between nettings and meat could prevent or minimize formation of the above nitrosamines. None was effective. However, cured pork products packaged in a reformulated rubber netting, made with different amine additives, contained either none or only negligible levels of NDBA or NDEA, but, instead, contained 8–104 ppb levels of a new nitrosamine, N‐nitrosodibenzylamine which is reported to be noncarcinogenic.

Volatile nitrosamines in cured meats packaged in elastic rubber nettings

Mise en evidence au niveau des filets, de taux de nitrosamines (N-nitrosodiethylamine et N-nitroso-di-n-butylamine surtout) de l'ordre de 0,5 ppm. Dans les viandes salees on trouve encore des teneurs notables en nitrosamines (0,03 ppm). Mecanismes de formation de ces nitrosamines