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101.
The involvement of nitrate and nitrite in the formation of N-nitrosamines in foods is a matter of great concern. This situation has led to revise the real amount of nitrate and nitrite needed in meat products to exert proper technological and safety activities, and also to extensive research to find alternatives to their use. The present study addresses the possibility of reducing the ingoing amounts of these additives below the legal limits established by the current European regulations. Different concentrations of nitrate and nitrite were tested on Spanish salchichón-type dry fermented sausages concerning their role in the microbiota and volatile profile. Sausages were manufactured with the maximum ingoing amounts established by the EU regulations (150 ppm NaNO3 and 150 ppm NaNO2), a 25% reduction and a 50% reduction; control sausages with no nitrate/nitrite addition were also prepared. The mixtures were inoculated with 5 log cfu/g of Listeria innocua as a surrogate for Listeria monocytogenes. L. innocua numbers in the final product were approximately 1.5 log cfu/g lower in the batch with the maximum nitrate/nitrite concentration when compared to 25 and 50% reduced batches, and about 2 log cfu/g in comparison to the control sausages. The final numbers of catalase-positive cocci were 1 log cfu/g higher in the 50% nitrate/nitrite reduced batch and 2 log cfu/g higher in the control sausages, compared to products manufactured with the maximum nitrate/nitrite concentration. This increase was related to a higher amount of volatile compounds derived from carbohydrate fermentation and amino acid degradation. Sausages with no addition of nitrate/nitrite showed higher amount of volatiles from lipid oxidation. Enterobacteriaceae counts reached detectable values (1-2 log cfu/g) in both nitrate/nitrite reduced sausages and in the control batch, while these organisms were not detected in the batch with the maximum ingoing amount. Nitrate and nitrite exerted a significant effect on the typical microbiota of dry fermented sausages and effectively contributed to control Listeria. These considerations should be taken into account in view of a future restriction in the use of these curing additives. 相似文献
102.
A nitrate-selective electrode based on surfactant-modified zeolite (SMZ) particles into carbon paste was proposed (SMZ-CPE). The electrode was fully characterized in terms of composition, response time, ionic strength, thermal stability and usable pH range. The electrode containing 10% SMZ exhibited linear response range to nitrate species in the range of 1.00 × 10−6 to 1.00 × 10−3 M with a detection limit of 1.00 × 10−6 M and a Nernstian slope of 59.4 ± 0.7 mV per decade of nitrate concentration. The response of the electrode to nitrate remains constant in the pH ranges of 3.5–9.8 and 1.7–10.5 for 1.00 × 10−4 and 1.00 × 10−2 M nitrate, respectively, and in presence of 1 × 10−4 to 1 × 10−3 M NaCl. The response of the electrode reaches to its equilibrium value within several seconds (10 s) after immersing the electrode in nitrate solution. Selectivity coefficients showed multivalent anions (such as arsenate, dichromate and sulfate) have higher interferences than monovalent anions (such as iodide, fluoride, bromide, chloride and thiocyanate). The electrode was used for determination of nitrate in an ammonium nitrate fertilizer sample, using direct potentiometry, and the satisfactory results were obtained. The electrode was also used for the potentiometric titration of nitrate. The validation of the obtained results in each case was proved by statistical “t” and “g” tests. 相似文献
103.
Ozonation and advanced oxidation processes (AOP) are very efficient methods for the destruction of refractory organic matters. These virtues have always been related to the production of hydroxyl radicals HO?, which are extremely powerful and non-selective oxidants. In this study, the O3-UV process is used as an AOP, where hydroxyl radicals are generated from the photodecomposition of ozone by short wavelength ultraviolet radiation. The obtained results indicated a weak scavenging effect of tert-butanol proving that hydroxyl radicals and ozone are not the only oxidants existing in the medium. Moreover, bicarbonate, known for a long time as effective HO? radical scavengers, does not slow down the oxidation of benzoic acid, but surprisingly increases it. Chlorides significantly decrease the degradation of organic compounds through their reaction with HO? radicals to produce chlorine. Carbonate radicals, nitrate and nitrogenated species as peroxynitrite/?peroxynitrous acid are involved in the oxidative mechanisms. 相似文献
104.
M. Gratacós-Cubarsí C. SárragaM. Castellari M.D. GuàrdiaJ.A. García Regueiro J. Arnau 《Meat science》2013
The effect of the amount of added nitrate and nitrate plus nitrite to dry-cured hams on the vitamin (B1, B2, B3, B6) content, the antioxidant enzyme superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx) activities and the thiobarbituric acid reactive substances (TBARS) was assessed in Gastrocnemius muscle at the end of two ripening processes. Five different curing mixtures (Hi–N: 600 KNO3; Lo–N: 150 KNO3; Hi–Mix: 600 KNO3 + 600 NaNO2; Lo–Mix: 150 KNO3 + 150 NaNO2; Hi–Mix/Asc: 600 KNO3 + 600 NaNO2 + 500 sodium ascorbate, expressed as mg of salts added on surface per kg of fresh ham) were evaluated in dry-cured hams aged for 11.5 months (standard process, SP) and 22 months (long process, LP). 相似文献
105.
针对碳气凝胶电极电吸附除盐工艺去除硝酸盐过程中存在的问题,采用电解水催化还原工艺作为其后续工艺,在原碳气凝胶电吸附除盐工艺装置上,进行了一系列平衡试验,对其影响因素进行了研究.结果表明,可以在不增加任何设备的情况下,大幅提高碳气凝胶电极电吸附除盐工艺去除硝酸盐的效果,并使电极得到再生. 相似文献
106.
硝酸盐作为地浸采铀氧化剂工业化应用研究 总被引:2,自引:0,他引:2
报道了对硝酸根在氧化浸出和吸附淋洗中的作用和行为特点的研究情况。模拟试验和现场试验结果均表明,硝酸根在地浸采铀中是一种良好的氧化剂,同时又是良好的淋洗剂。且具有工艺简单、外排尾液少的优点,能明显的降低铀的开采成本。这一工艺对地浸采铀和其他矿物的原地浸出开采都有一定的应用价值。 相似文献
107.
108.
Modification of the ion exchange HPLC procedure for the detection of nitrate and nitrite in dairy products 总被引:1,自引:0,他引:1
Existing ion exchange HPLC methodology for nitrate and nitrite analysis in cured meat products suffers from high analyte variability at low concentrations and also chromatographic interference by artifacts in some other foods, such as dairy products. An investigation into the sources of variability has shown that both the cyclohexyl solid phase extraction cartridge and the glass fibre filter used in the original method can introduce artifacts which interfere with the determination of the nitrate in foodstuffs. We have also found that the use of a graphitized solid phase extraction cartridge used in tandem with the cyclohexyl solid phase extraction cartridge removed the artifacts from the chromatograph of dairy products that co-eluted with nitrite and nitrate. Values for the nitrite and nitrate content of dairy products were obtained by the HPLC procedure using these two solid phase extraction cartridges and the values obtained were in close agreement with those obtained by cadmium column reduction and colorimetry. 相似文献
109.
A novel method using redox reactions among nitrite and permanganate anions in NaOH solutions i.e. 8 and 16 mol/L was used for the synthesis of nitrate cancrinites. Reactions were carried out at 80 °C under autogenous pressure for 40 h. Zeolite X was used as silicon and aluminum source. Obtained polycrystals were characterized by using powder X-ray diffraction (XRD) and FT-IR spectroscopy. Results showed that only the nitrated cancrinite was obtained in a wide range of basicities and NO2−/MnO4− compositions. 相似文献
110.
Groundwater constitutes the largest single source of fresh water in many parts of the world and provides a risk buffer to
sustain critical water demands during cyclic and prolonged dry periods, especially in semi-arid and arid regions. However,
unprecedented socio-economical growths are threatening the viability of these precious resources through fast depletion of
already critically low stocks accompanied by persistent degradation of water quality due to salinization, and contamination
by pesticides and fertilizers, urban sewage and industrial waste. These circumstances are particularly true of the Upper Litani
Basin (ULB), which houses over 500,000 of Lebanon’s 4 million population and provides the bulk of the country’s agricultural
output. Uncontrolled urban, agricultural and industrial growths following a prolonged civil strife and foreign occupation
have resulted in the deterioration of the quality of the basin’s surface water and potentially its groundwater resources.
An assessment study of groundwater quality conditions in the ULB was conducted in support of efforts to manage water quality
in the basin. Geostatistical analysis of groundwater nitrate levels was conducted using data collected through an extensive
basin-wide water quality survey sponsored by the USAID and covered two periods representing the summer and winter periods.
The results of analysis include maps of nitrate contamination and probability of exceedance of drinking-water nitrate regulatory
limit. The results indicate a significant, widespread and persistent nitrates contamination of groundwater in the ULB. Nitrate
levels in groundwater exceed standard limits for drinking water in many parts of the basin. These findings were examined with
respect to those of a DRASTIC groundwater vulnerability assessment conducted by the USAID BAMAS project. Comparative analysis
of the two assessments shed the light on several issues related to the application and interpretation of DRASTIC scores and
the groundwater nitrate contamination process. 相似文献