济宁市售蔬菜中硝酸盐和亚硝酸盐含量分析

对济宁市售８类２７种蔬菜中硝酸盐、亚硝酸盐含量的测定的结果表明：不同种类的蔬菜中硝酸盐的含量差别很大（１４０．６～２７６２．５ｍｇ／ｋｇ），亚硝酸盐的含量在新鲜蔬菜中很低，（０．２０～２．８５ｍｇ／ｋｇ）     

南京市市售蔬菜硝酸盐和亚硝酸盐污染状况分析

目的:掌握南京市市售蔬菜中硝酸盐和亚硝酸盐的污染情况,为蔬菜供应安全及安全生产管理提供理论依据.方法:在南京市农贸市场和蔬菜批发市场共11个采集点采集44种蔬菜样品980份,用国标法(GB/T5009.33)分析蔬菜中的硝酸盐和亚硝酸盐含量.结果:不同种类蔬菜中硝酸盐含量差别较大,硝酸盐的含量依次为特菜类＞叶菜类＞茎类＞块根类＞瓜菜类＞甘蓝类＞果菜类＞豆类＞鳞茎类＞菌类;同一类别不同品种蔬菜中硝酸盐含量差别亦较大,从几倍至几十倍;检测的样品中,硝酸盐处于严重污染状态的占28.16％.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.结论:南京市市售蔬菜中硝酸盐污染较为严重,应引起足够重视,加强监督管理.     

浓度直读法快速测定蔬菜中的硝酸盐和亚硝酸盐含量

目的：建立快速测定蔬菜中硝酸盐和亚硝酸盐含量的方法。方法：利用硝酸根离子选择性电极和离子分析仪，采用浓度直读的方式，同时测定蔬菜中硝酸盐（NO3^-）和亚硝酸盐（NO2^-）。对干扰离子的影响及消除方法、TISAB溶液的选取、测定条件的控制、方法的准确度和精密度等进行了系统探讨。结果：NO3^-的相对标准偏差为0．46％，NO2^-的相对标准偏差为1．18％，对NO3^-的回收率为97．4％-104．7％，对NO2^-的回收率为98．6％-99．8％。结论：该法简便、快速、准确，可用于蔬菜中硝酸盐和亚硝酸盐含量的测定。     

蔬菜中硝酸盐、亚硝酸盐含量及卫生学评价

本文研究了北京市41个品种174件蔬菜样品中硝酸盐、亚硝酸盐的含量。估计从新鲜蔬菜中平均每人每日摄入硝酸盐268mg,亚硝酸盐0.049mg。并参考WHO建议的硝酸盐的ADI值,进行卫生学评价。     

离子色谱法测定蔬菜中硝酸盐和亚硝酸盐

目的探讨离子色谱测定蔬菜中硝酸盐和亚硝酸盐。方法对离子色谱测定蔬菜中硝酸盐和亚硝酸盐的条件进行优化,同时进行方法学对照及实际样品测定。结果NO-2其变异系数为2.5%,加标回收率为99%～103%;NO-3其变异系数为1.1%,加标回收率为98%～102%,对照实验t相似文献   

2011年云南省市售熟肉制品中硝酸盐和亚硝酸盐含量检测结果分析

目的:了解2011年云南省市售熟肉制品中硝酸盐和亚硝酸盐含量,为加强食品安全管理监督提供科学依据。方法:根据GB/T5009.33-2010《食品中亚硝酸盐和硝酸盐的测定》采用分光光度法对抽检样品的硝酸盐和亚硝酸盐进行检测,并对检测结果进行统计分析。结果:本次抽检的191件熟肉样品中,硝酸盐检出率100%,合格率28.8%。亚硝酸盐的平均检出率85.3%,合格率99.5%。结论:在云南省市售熟肉制品的加工生产过程中,硝酸盐的使用普遍而且量大。亚硝酸盐的使用普遍但比较规范,基本按照食品添加剂的安全标准规定的允许量添加。     

奶粉中硝酸盐亚硝酸盐含量的调查

奶粉是一种营养最完全的食品，它含有人体必需的一切营养成分。是婴幼和和年老体经者常食用的一种最理想的食品。随着人们生活水平的不断提高，奶制品食品已进行千家万户。因而奶粉中掺假掺杂问题亦不要忽视，本文就１９９２年对我区流通领域内的部分奶粉的质量调查作一简单的分析。     

高氮施肥区蔬菜硝酸盐及亚硝酸盐调查

目的了解高氮施肥区蔬菜硝酸盐及亚硝酸盐污染情况。方法于2011年7—10月选择沙颍河上游地区每月采样,共采集27种、136个蔬菜样品检测硝酸盐、亚硝酸盐含量并进行初步的健康风险评估。结果 8—9月蔬菜硝酸盐含量较高,10月最低;9月蔬菜亚硝酸盐含量最高,7—8月较低,10月最低;7—10月份6类蔬菜亚硝酸盐含量超标(4.00mg/kg)率为41.67%,10月均达标。蔬菜硝酸盐健康风险指数除10月外均1;亚硝酸盐健康风险指数均1。结论该区域蔬菜硝酸盐和亚硝酸盐蓄积水平较高,且硝酸盐存在一定的健康风险。     

乳制品中硝酸盐、亚硝酸盐测定中问题的探讨

牛乳中含有蛋白质、脂肪、乳糖、多种维生素和矿物质等主要的营养要素.目前各类品种繁多的乳制品不断涌入市场,随着人们生活水平的提高,越来越多的家庭把牛奶当作每日不可缺少的必需品.因此,牛奶质量的好坏直接影响到人们的身体健康.亚硝酸盐在细菌的作用下,可变成亚硝酸胺类,人体过多摄入亚硝酸盐会出现呕吐、腹泻、腹痛等症状。     

离子色谱法同时测定婴幼儿奶粉中的硝酸盐和亚硝酸盐

[目的]建立离子色谱法同时测定婴幼儿奶粉中硝酸盐和亚硝酸盐含量的方法。[方法]样品经3%乙酸去除脂肪和蛋白质后,离心,上清液用0.22μm滤膜过滤,20℃温度下,经阴离子分析柱MetrosepASupp5-2504.0mm×250mm分离,电导检测器检测。[结果]硝酸盐、亚硝酸盐浓度分别在0.25～4.00mg/L、0.10～1.50mg/L范围内显良好的线性关系(r1=0.9997、r2=0.9999),方法回收率分别为90.2%～104%、91.0%～106%,RSD分别为1.83%～3.82%、1.35%～4.15%,最低检出浓度分别为0.04mg/L、0.05mg/L。[结论]实验表明,该法样品处理简单,测定快速,灵敏度高,满足婴幼儿奶粉中硝酸盐和亚硝酸盐含量的同时测定。     

济南市蔬菜中硝酸盐含量与预防对策研究

本文调查分析了1995～1997年间,济南市区9类17种新鲜蔬菜可食部分的硝酸盐积累状况,并根据WHO/FAO规定的ADI值换算得到的标准进行总体评价,并提出相应的防治对策与措施。     

Nitrate and Nitrite Content of Well Water in Enugu,Southeast Nigeria

Water samples from 20 artesian wells, chosen by the multistage sampling procedure from 5 zones in the city of Enugu, Southeast Nigeria, were analyzed by the disulfonic acid method in duplicate for the presence of nitrate (NO₃) and nitrite (NO₂). The zonal mean values for NO₃ were 0.45 mmol/l, 0.46 mmol/l, 0.55 mmol/l, 0.59 mmol/l, and 0.65 mmol/l (mean = 0.54 mmol/l), and for NO₂ the values were 0.34 mmol/l, 0.32 mmol/l, 0.21 mmol/l, 0.14 mmol/l, and 0.20 mmol/l (mean = 0.24 mmol/l), respectively. The mean values were reciprocally related (r = -.7356, p = 0.0002), indicating fecal contamination of well water. There were no significant differences between the mean values and the sum of the NO₃ and NO₂ values of the samples (p > 0.05), indicating uniform nitrogen content in the region. The mean value for NO₃ (0.54 mmol/l) was below the guideline values set by the World Health Organization, but the mean NO₂ concentration of 0.24 mmol/l was much higher (290%) than what is considered safe for humans.     

泡菜中硝酸盐和亚硝酸盐的离子色谱测定法

目的建立同时测定泡菜中亚硝酸盐和硝酸盐含量的离子色谱法。方法采用超声提取,高速离心固相萃取柱净化的方法对样品进行处理,高容量阴离子色谱柱分离,抑制型电导检测器检测。结果该法线性相关性好（RNO2-=0．9993,RNO3-=0．9997）,亚硝酸盐和硝酸盐最低检出限分别为0．006和0．008mg／L,平均回收率分别为96．2％和103．4％,方法精密度分别为2．43％和1．88％。结论该方法操作简单,灵敏度高,线性范围宽,结果准确可靠,特别适合于泡菜中硝酸盐和亚硝酸盐同时测定。     

Nitrite and Nitrate Concentrations and Metabolism in Breast Milk,Infant Formula,and Parenteral Nutrition

Dietary nitrate and nitrite are sources of gastric NO, which modulates blood flow, mucus production, and microbial flora. However, the intake and importance of these anions in infants is largely unknown. Nitrate and nitrite levels were measured in breast milk of mothers of preterm and term infants, infant formulas, and parenteral nutrition. Nitrite metabolism in breast milk was measured after freeze‐thawing, at different temperatures, varying oxygen tensions, and after inhibition of potential nitrite‐metabolizing enzymes. Nitrite concentrations averaged 0.07 ± 0.01 μM in milk of mothers of preterm infants, less than that of term infants (0.13 ± 0.02 μM) (P < .01). Nitrate concentrations averaged 13.6 ± 3.7 μM and 12.7 ± 4.9 μM, respectively. Nitrite and nitrate concentrations in infant formulas varied from undetectable to many‐fold more than breast milk. Concentrations in parenteral nutrition were equivalent to or lower than those of breast milk. Freeze‐thawing decreased nitrite concentration ~64%, falling with a half‐life of 32 minutes at 37°C. The disappearance of nitrite was oxygen‐dependent and prevented by ferricyanide and 3 inhibitors of lactoperoxidase. Nitrite concentrations in breast milk decrease with storage and freeze‐thawing, a decline likely mediated by lactoperoxidase. Compared to adults, infants ingest relatively little nitrite and nitrate, which may be of importance in the modulation of blood flow and the bacterial flora of the infant GI tract, especially given the protective effects of swallowed nitrite.     

Effect of Vitamin C and Protein Supplementation on Plasma Nitrate and Nitrite Response following Consumption of Beetroot Juice

Beetroot juice is a food high in nitrate and is associated with cardiometabolic health benefits and enhanced exercise performance through the production of nitric oxide in the nitrate–nitrite–nitric oxide pathway. Since various food components influence this pathway, the aim of this trial was to study the effect of beetroot juice alone and in conjunction with vitamin C or protein on the acute response to plasma nitrate and nitrite levels in healthy middle- to older-aged adults. In this cross-over trial, each participant received, in a randomized order, a single dose of Beet It Sport^® alone; Beet It Sport^®, plus a 200 mg vitamin C supplement; and Beet It Sport^® plus 15 g of whey protein. Plasma levels of nitrate and nitrite were determined prior to and at 1 and 3 h after intervention. Log plasma nitrate and nitrite was calculated to obtain data that were normally distributed, and these data were analyzed using two-way within-factors ANOVA, with time and treatment as the independent factors. There were no statistically significant differences for log plasma nitrate (p = 0.308) or log plasma nitrite (p = 0.391) values across treatments. Log plasma nitrate increased significantly from pre-consumption levels after 1 h (p < 0.001) and 3 h (p < 0.001), but plasma nitrate was lower at 3 h than 1 h (p < 0.001). Log plasma nitrite increased from pre to 1 h (p < 0.001) and 3 h (p < 0.001) with log values at 3 h higher than at 1 h (p = 0.003). In this cohort, we observed no differences in log plasma nitrate and nitrite at 1 h and 3 h after co-ingesting beetroot juice with vitamin C or a whey protein supplement compared to beetroot juice alone. Further research needs to be undertaken to expand the blood-sampling time-frame and to examine factors that may influence the kinetics of the plasma nitrate to nitrite efficacy, such as differences in fluid volume and osmolarity between treatments employed.     

加工方法及存放时间对蔬菜亚硝酸盐含量的影响

目的　了解不同加工方法及加工后存放时间对蔬菜亚硝酸盐含量影响的规律 ,为减少亚硝酸盐危害提供依据。方法　采用萘基盐酸二氨基乙烯法检测新鲜及经加工的蔬菜中亚硝酸盐含量并进行分析。结果　蔬菜中亚硝酸盐含量受加工方法、存放时间影响。腌芹菜比炒芹菜亚硝酸盐含量高 ;差异具显著性 (P<0 .0 1 ) ;经加工的青菜放置 2 4h后亚硝酸盐含量持续增加。结论　少吃腌菜、剩菜 ,可以减少亚硝酸盐危害。     

Plasma Nitrate and Nitrite Kinetics after Single Intake of Beetroot Juice in Adult Patients on Chronic Hemodialysis and in Healthy Volunteers: A Randomized,Single-Blind,Placebo-Controlled,Crossover Study

Nitric oxide (NO) contributes to maintaining normal cardiovascular and renal function. This bioactive signalling molecule is generally formed enzymatically by NO synthase in the vascular endothelium. NO bioactivity can also be attributed to dietary intake of inorganic nitrate, which is abundant in our diet, especially in green leafy vegetables and beets. Ingested nitrate is reduced to nitrite by oral commensal bacteria and further to NO systemically. Previous studies have shown that dialysis, by means of removing nitrate and nitrite from the body, can reduce NO bioactivity. Hence, dietary intervention approaches aimed to boost the nitrate–nitrite–NO pathway may be of benefit in dialysis patients. The purpose of this study was to examine the kinetics of plasma nitrate and nitrite after a single intake of nitrate-rich concentrated beetroot juice (BJ) in adult hemodialysis (HD) patients and in age-matched healthy volunteers (HV). Eight HD patients and seven HV participated in this single center, randomized, single-blind, placebo-controlled, crossover study. Each participant received a sequential single administration of active BJ (70 mL, 400 mg nitrate) and placebo BJ (70 mL, 0 mg nitrate) in a random order separated by a washout period of seven days. For the kinetic analysis, blood samples were collected at different time-points before and up to 44 h after BJ intake. Compared with placebo, active BJ significantly increased plasma nitrate and nitrite levels both in HD patients and HV. The area under the curve and the maximal concentration of plasma nitrate, but not of nitrite, were significantly higher in HD patients as compared with HV. In both groups, active BJ ingestion did not affect blood pressure or plasma potassium levels. Both BJs were well tolerated in all participants with no adverse events reported. Our data provide useful information in planning dietary nitrate supplementation efficacy studies in patients with reduced NO bioactivity.