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The contents of nitrate and nitrite in lettuce, leek, potato, beetroot, Chinese cabbage and white cabbage on the Danish market were determined for 3 years in the period 1993-1997 as part of the Danish food monitoring programme. These vegetables are supposed to provide the major contribution to the intake of nitrate from the diet. Results for nitrate and nitrite in fresh and frozen spinach are also shown. The highest content of nitrate was found in lettuce followed by beetroot, Chinese cabbage, fresh spinach, leek, frozen spinach, white cabbage and potatoes. For all the products a great variation in the content of nitrate was found. For lettuce a characteristic variation throughout the year is clearly seen with the highest content in the winter period the lowest content in the summer period. Generally, the content of nitrite was low but in spinach high contents were found, probably due to improper storage conditions during transportation. The intake of nitrate and nitrite from these vegetables is calculated on the basis of two different consumption surveys. For both surveys the average intake of nitrate from the vegetables included in the monitoring programme is estimated to be approximately 40mg day-1, whereas for nitrite the average intake is approximately 0.09mg day-1. The total intake of nitrate and nitrite is estimated to be respectively 61mg day-1 and 0.5mg day-1. 相似文献
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The nitrate and nitrite content of leaf vegetables (Swiss chard, sea beet, spinach and cabbage), “inflorescence” vegetables (cauliflower) and fruit vegetables (eggplant and vegetable marrow) grown with organic fertilizers have been determined by a modified cadmium–Griess method. Samples were purchased from organic food stores as well as collected directly from an organic farm in Madrid (Spain). Nitrate levels were much higher in the leaf vegetables (especially Swiss chard species; average over the different samples and species of 2778.6 ± 1474.7 mg kg? 1) than in inflorescence or fruit products (mean values between 50.2 ± 52.6 and 183.9 ± 233.6 mg kg? 1). Following Swiss chard species, spinach (1349.8 ± 1045.5 mg kg? 1) showed the highest nitrate content, and nitrite was found above the limit of detection in some samples only (spinach, 4.6 ± 1.0 mg kg? 1; sea beet, 4.2 ± 0.7 mg kg? 1 and Swiss chard, 1.2 ± 0.4 mg kg? 1). Some vegetables (spinach, cabbage and eggplant) had lower nitrate content in the samples harvested in summer, showing the influence of climatic conditions on the nitrate levels in a plant. The samples taken directly from the organic farm, with the exception of eggplant, had higher or slightly higher average nitrate values than samples purchased in the organic food stores, ranging from 117 to 1077%. 相似文献
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A flow-injection spectrophotometric method for nitrate and nitrite determination through nitric oxide generation 总被引:3,自引:0,他引:3
Raquel Andrade Claudia O. Viana Silvane G. Guadagnin Felix G. R. Reyes Susanne Rath 《Food chemistry》2003,80(4):597-602
A flow injection method with novel spectrophotometric detection for the determination of nitrite and nitrate in foodstuffs is presented. The method is based on the reduction of nitrite and nitrate to nitric oxide, with subsequent reaction with iron (II) and thiocyanate in an acid medium, forming FeSCNNO+. The absorbance of the complex, with a maximum at 460 nm, is proportional to the nitrite and nitrate concentrations. The NO is generated in two stages: (1) reduction of nitrate to nitrite in a cadmium copper reductor column and (2) reduction of the nitrite to NO in a sulfuric acid medium. The influence of reagent concentrations and manifold parameters were evaluated. Nitrite and nitrate can be determined in the range of 0.30–3.00 and 1.00–10.00 mg l−1, respectively. The sampling rate of analyses was 30–40 h−1 and, considering a sample of 5.0 g, the determination limit of the method was 20 and 13 mg kg−1 of nitrate and nitrite, respectively. Nitrite and nitrate were determined in vegetables and meat products by the proposed method. The precision and accuracy of the proposed method were comparable to those of the reference spectrophotometric method (official AOAC reference method for the determination of nitrate in foodstuffs). 相似文献
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用硝酸根电极同时测定肉制品中硝酸盐和亚硝酸盐含量。以0.1mol/l硫酸钠作为总离子强度调节剂,在pH3.4±0.1,硝酸根电极在硝酸钠4.0—30μg/ml浓度范围内呈良好的能斯特应答。一次标准加入法定量。在酸性条件下,用过氧化氢氧化提取液中NO_2~-,测得NO_3~-总量,然后用差减法求得NO_2~-含量。用本法测定了13种市售肉制品中硝酸盐和亚硝酸盐含量。变异系数2.31%—9.83%,回收率95.0%—108.4%。用NO_3~-和镉柱还原法,NO_2~-和萘乙二胺比色法进行了对照,结果无显著性差异(α0.05)。 相似文献
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David J Lyons George E Rayment Peter E Nobbs Leith E McCallum 《Journal of the science of food and agriculture》1994,64(3):279-281
Vegetables were collected near peak harvest from the main production regions in Queensland and were analysed for residues of nitrate and nitrite. A small sample of hydroponic produce was also included in the survey. Nitrite-N from 1 to 4 mg kg-1 was found only in dwarf beans and in lettuces. Levels of nitrate in potatoes, cabbages and beets were higher than those reported in other surveys and exceeded threshold limits set in one other country. The median nitrate-N concentration measured in hydroponic lettuce (465 mg kg-1 nitrate-N) was more than twice the median concentration for field-grown lettuce. Poor correlation between total N and nitrate in vegetables raises doubts about the use of total N alone as an indicator of N status. 相似文献
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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
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Pietro Santamaria 《Journal of the science of food and agriculture》2006,86(1):10-17
Nitrate content is an important quality characteristic of vegetables. Vegetable nitrate content is of interest to governments and regulators owing to the possible implications for health and to check that controls on the content are effective. Nitrate itself is relatively non‐toxic but its metabolites may produce a number of health effects. Until recently nitrate was perceived as a purely harmful dietary component which causes infantile methaemoglobinaemia, carcinogenesis and possibly even teratogenesis. Recent research studies suggest that nitrate is actually a key part of our bodies' defences against gastroenteritis. In this review are reported: (1) vegetable classification as a function of nitrate accumulation; (2) vegetable contribution to the total dietary exposure of nitrate; (3) European Commission Regulation No. 563/2002 which sets limits for nitrate in lettuce and spinach; (4) the maximum levels set in some countries for beetroot, cabbage, carrot, celery, endive, Lamb's lettuce, potato, radish and rocket; (5) the results of surveys on the nitrate content of vegetables in Italy and other European countries. Copyright © 2005 Society of Chemical Industry 相似文献
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High dietary nitrate and nitrite intake may increase the risk of gastro-intestinal cancers due to the in vivo formation of carcinogenic chemicals known as N-nitroso compounds. Water and leafy vegetables are natural sources of dietary nitrate, whereas cured meats are the major sources of dietary nitrite. This paper describes a simple and fast analytical method for determining nitrate and nitrite contents in vegetables and meat, using reversed-phase HPLC-UV. The linearity R2 value was >0.998 for the anions. The limits of quantification for nitrite and nitrate were 5.0 and 2.5 mg/kg, respectively. This method is applicable for both leafy vegetable and meat samples. A range of vegetables was tested, which contained <23 mg/kg nitrite, but as much as 5000 mg/kg of nitrate. In cured and fresh meat samples, nitrate content ranged from 3.7 to 139.5 mg/kg, and nitrite content ranged from 3.7 to 86.7 mg/kg. These were below the regulatory limits set by food standards Australia and New Zealand (FSANZ). Based on the average consumption of these vegetables and cured meat in Australia, the estimated dietary intake for nitrate and nitrite for Australians were 267 and 5.3 mg/adult/day, respectively. 相似文献
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为了解北京市蔬菜中硝酸盐和亚硝酸盐的污染情况 ,于 2 0 0 3年 4月~ 8月从北京 15个菜市场采集应季蔬菜样品 ,共 4 0个品种 4 44份样品 ,用国标法 (GB T 5 0 0 9 33— 2 0 0 3)分析蔬菜中的硝酸盐和亚硝酸盐的含量。结果显示 :检测样品中 ,污染程度严重的占 33 1% ;中、重度污染的占2 3 6 % ;轻度的占 4 3 2 % ;硝酸盐的含量依次为绿叶菜类 >白菜类 >根茎类 >瓜茄类 >葱蒜类 >豆类 >果类 >水生植物类 ,但同一类蔬菜不同品种的硝酸盐的含量差别较大 ,从几倍到几十倍 ;同一品种的蔬菜中硝酸盐含量差别也很大 ,可能与产地、生长条件不同有关。蔬菜中亚硝酸盐含量相对较低 ,其含量与蔬菜的新鲜程度有关。研究结果提示需要制定限量标准 ,加强监督管理 相似文献
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To evaluate nitrate and nitrite contents in cabbage and potatoes, the most consumed vegetables in Croatia, and to examine if war-time operations in Croatia affected nitrate and nitrite levels in vegetables, potatoes and cabbage cultivated in the war region (East Slavonia) and out of war regions were analyzed. Data showed that nitrate contents were higher in the samples from the war region (32% and 24% in potatoes and cabbage, respectively) but differences were not statistically significant. The nitrate levels found in potato samples (196 mg NaNO3/kg fresh weight (FW) and cabbage samples (911 mg NaNO3/kg FW) were comparable with levels reported for other countries. The nitrite contents in potatoes (321 μg NaNO2/kg FW) and cabbage (173 μg NaNO2/kg FW) were lower than the contents reported for most other countries. Further examinations of nitrate and nitrite concentrations in vegetables in Croatia as well as examinations of the influence of war-time operations on accumulation of these toxic contaminants are necessary. 相似文献
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Monitoring of nitrate (NO3-) and nitrite (NO2-) content in agricultural products in Slovenia has been carried out since 1996. The results of monitoring over the period 1996-2002 are presented. During this time 924 samples of 14 different agricultural products (potato, lettuce, apples, carrot, silage maize, cabbage, grapes, peaches, string beans, cereals, pears, cucumbers, strawberries and tomato) were analysed. The samples were taken at the time of maturity directly from growing sites and they were analysed using segmented flow analysis. The average nitrate contents were the highest in lettuce (1074 mg kg-1), cabbage (881 mg kg-1), string beans (298 mg kg-1) and carrot (264 mg kg-1), and they were moderately high in potato (158 mg kg-1), silage maize (122 mg kg-1), strawberries (94 mg kg-1), cucumbers (93 mg kg-1) and cereals (49 mg kg-1). Low nitrate contents (below 6 mg kg-1) were found in fruit (grapes, peaches, apples and pears) and tomato. With the exception of cereals (8.9 mg kg-1), apples (1.5 mg kg-1), potato (1.2 mg kg-1) and pears (1.0 mg kg-1) the content of nitrites did not exceed 0.5 mg kg-1. It may be concluded that the results of the monitoring were in most cases similar to the results of investigations obtained in other countries. 相似文献
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Libo Liu Peng Du Guofang Zhang Xue Mao Yucai Zhao Jingying Wang 《International Journal of Food Properties》2017,20(11):2448-2455
The safety of northeast sauerkraut (NS) has always been a concern in China. In the present study, the nitrite and biogenic amine (BA) contents in 378 NS, collected or purchased from Chinese families and markets (including morning markets and local supermarkets), were measured. The results showed that the nitrite and BA contents of samples from Chinese families and some morning markets were higher than those from local supermarkets. The highest level of nitrites was 38.5 ± 5.2 mg/kg in unpackaged NS from Chinese families, and the lowest was 17.2 ± 2.1 mg/kg in packaged NS from local supermarkets. The highest levels of tyramine and tryptamine were 203 ± 3 and 28.1 ± 4 mg/kg in unpackaged NS from Chinese families, respectively. The highest levels of histamine, putrescine, and cadaverine were mainly found in Chinese families and morning markets, and the lowest level of BAs was from local supermarkets. The results suggest that improving the safety of NS by controlling environmental sanitation and strengthening standardised production is a top priority at present in China. 相似文献