NITRATE AND NITRITE CONTAMINATION IN VEGETABLES IN CHINA

This paper reviews recent studies of nitrate and nitrite contamination in Chinese vegetables. Nitrate and nitrite contamination is very serious and increases the amount of nitrogenous fertilizer applications. Factors influencing nitrate and nitrite contamination in vegetables are analyzed and discussed.     

青岛市售冬季大棚蔬菜中亚硝酸盐、硝酸盐含量的测定及安全性评价

蔬菜中亚硝酸盐、硝酸盐含量是其卫生品质的重要指标之一,研究运用格里斯试剂比色法及紫外分光光度法检测了青岛市场上冬季大棚蔬菜217个样品中亚硝酸盐、硝酸盐含量。结果表明,青岛市七区蔬菜市场上叶菜类硝酸盐污染较为严重,大部分蔬菜的亚硝酸盐处于轻、中度污染状态。研究为当地蔬菜的安全供应提供了理论依据和数据支持。     

厦门市售蔬菜重金属、硝酸盐和亚硝酸盐污染研究及评价

为了解厦门市蔬菜中有害重金属、硝酸盐和亚硝酸盐的污染情况,于2004年8月至2005年12月从厦门市各超市、农贸市场、蔬菜批发市场和蔬菜产地上采集46个品种532份蔬菜样品,用国标法(GB/T5009.11-17-1996、GB/T5009.33-2003)分别分析蔬菜中的重金属、硝酸盐和亚硝酸盐的含量。结果表明,检测样品中Pb、Cd、As、Hg、硝酸盐和亚硝酸盐的平均值分别为0.0099、0.083、0.056、0.003、1090.3、0.59mg/kg;根据国家标准1-2,仅部分品种如菠菜、甘蓝、花菜、萝卜的铅超标,有潜在污染风险;大部分蔬菜中砷、汞、镉三种重金属的含量都较低,潜在的污染风险不大。硝酸盐污染程度严重的占36.5%;中、重度污染的占20.2%;轻度的占43.3%,硝酸盐含量依次为嫩茎叶菜类>根茎类>花菜类>瓜菜类>鲜豆菜>茄果类>水生蔬菜类,各样品间含量差别较大;而蔬菜中亚硝酸盐含量相对较低。     

七种野菜硝酸盐和Vc含量的研究

对采自粤东地区的7种野生蔬菜的可食部分中硝酸盐、亚硝酸盐和Vc的含量进行测定，并参考WHO建议亚硝酸盐和硝酸盐的ADI值，进行卫生评价，结果表明，被测7种野菜的硝酸盐和亚硝酸盐的含量都低于限量标准；同时发现这7种野菜的Vc含量很高，营养丰富。     

蔬菜中硝酸盐和亚硝酸盐的污染

综述了硝酸盐和亚硝酸盐的危害、污染来源、蔬菜中的污染现状、蔬菜中硝酸盐积累机理及控制措施。     

蔬菜中硝酸盐和亚硝酸盐的污染

综述了硝酸盐和亚硝酸盐的危害、污染来源、蔬菜中的污染现状、蔬菜中硝酸盐积累机理及控制措施。     

离子色谱法测定蔬菜中NO3-和NO2-

研究建立一种有效测定蔬菜中硝酸盐和亚硝酸盐含量的方法，并对人们经常食用的26种蔬菜进行测定，计算其中的硝酸盐和亚硝酸盐的含量。实验证明：采用离子色谱法具有快速简便、灵敏度高、精密度高、回收率好等优点。     

蔬菜中亚硝酸盐和硝酸盐检测技术研究进展

硝酸盐和亚硝酸盐广泛存在于人们的生活中,人体外源性硝酸盐的摄入大多来自蔬菜。硝酸盐对人体没有直接危害,但它可以在人体内的酶和微生物的作用下转化为有毒的亚硝酸盐,使血液的输氧能力下降,导致高铁血红高蛋白症。蔬菜在人们的日常膳食中占据重要的地位,检测蔬菜中的硝酸盐含量具有重要的现实意义。本研究对蔬菜中硝酸盐和亚硝酸盐的检测技术进展进行了概述和比较,以期为蔬菜中硝酸盐和亚硝酸盐的检测及快速检测技术的发展提供基础参考。     

冷藏对蔬菜中亚硝酸盐及硝酸盐含量的影响

目的 探索冰箱冷藏(4℃)条件下蔬菜中硝酸盐和亚硝酸盐含量随时间的变化,对冷藏食品的安全性进行评价.方法 分别采用重氮偶合分光光度法和麝香草酚分光光度法对生菜、菠菜、油麦菜及苦苣4种常用蔬菜在冷藏条件下其亚硝酸盐及硝酸盐的含量变化进行测定.结果 1～4d内,生菜、苦苣中的亚硝酸盐含量随着时间的延长逐渐增加;菠菜、油麦菜中亚硝酸盐含量分别在第2天和第3天达到最大,之后逐渐降低,而菠菜中亚硝酸盐含量在第4天又出现上升趋势.4种蔬菜中亚硝酸盐含量4d中最大值仅为0.419 4 mg/kg(生菜),均＜4 mg/kg的限量值.苦苣和油麦菜中硝酸盐含量在1～4d内逐渐上升.菠菜中硝酸盐含量第2天达到418.48 mg/kg,之后又降低至20.83 mg/kg.生菜中硝酸盐含量在第3天达到最大值317.26 mg/kg,之后逐渐下降,但均在安全范围内(432 mg/kg).结论 在4℃下冷藏4d后,4种常见蔬菜均可安全食用.可见,冷藏能有效减缓亚硝酸盐和硝酸盐含量的升高.     

Nitrate and Nitrite Methods of Analysis and Levels in Raw Carrots, Processed Carrots and in Selected Vegetables and Grain Products

Methods for quantitative estimation of nitrate and nitrite were compared. Levels of these ions were measured in vegetables and grain products and effects of processing on nitrate and nitrite levels in carrots were measured. These data allow more accurate estimation of ingestion levels and suggest means to reduce exposure to these ions. High performance liquid chromatography (HPLC) had better precision and recoveries than either a classical Cd-Griess method nitrate or a Griess method for nitrite. Nitrate concentration by HPLC varied greatly within and between vegetables, ranging from 1 μmol/100g in mushrooms to 5000 μmol/100g in celery and averaging 9.7 ± 4.4 μmol/100g in grains. Nitrate levels in vegetables sold as “organic” were not different (p<0.05) from conventional vegetables. No nitrite was detected in either vegetables or grains. Nitrate was unevenly distributed in carrots with the core having the most. Storage of carrots at -18°C for 10 wk did not alter nitrate levels and no nitrite developed. Fifty-seven percent of nitrate was leached into cooking liquid when frozen carrots were boiled. Thirty-two percent of nitrate was lost during canning and 47% of the remainder was in the liquid. No nitrite developed during 10 wk of canned storage.     

蔬菜中硝酸盐与亚硝酸盐的积累规律与控制方法

目前对蔬菜生产和加工中硝酸盐和亚硝酸盐的形成积累规律还缺乏清楚的认识和理解,对蔬菜中硝酸盐含量也没有系统的控制方法。文章对蔬菜,特别是叶类蔬菜中硝酸盐和亚硝酸盐的积累规律和控制方法进行了综述,以指导无公害蔬菜的生产。     

蔬菜中硝酸盐和亚硝酸盐检测方法的研究进展

硝酸盐和亚硝酸盐主要通过蔬菜食用进入人体,亚硝酸盐是一种有毒物质,人食用后会在体内产生致癌性 的亚硝胺。光谱法、色谱法、快速检测法是目前检测蔬菜中硝酸盐和亚硝酸盐的主要方法。本文在对上述方法进行 介绍并比较的基础上,对蔬菜中硝酸盐和亚硝酸盐检测方法的研究进展进行了概述与展望。     

替代亚硝酸盐生产安全腌肉制品的研究现状

硝酸盐和亚硝酸盐在腌肉制品加工中同时起着发色、抑菌、抗氧化和提高风味的作用,但硝酸盐和亚硝酸盐与肉中的二级胺反应会形成致癌物质N-亚硝胺,所以寻求一种更加安全有效的硝酸盐和亚硝酸盐替代方式,在实际生产中具有重要意义。本文就无硝腌肉制品在亚硝酸盐发色作用、抑菌作用和抗氧化作用的替代物方面开展的研究工作进行综述,提出了天然腌制的概念,重点介绍目前国内外利用蔬菜替代亚硝酸盐的方法,包括将蔬菜粉(或汁)中的硝酸盐用硝酸盐还原菌转化为亚硝酸盐后加入腌肉制品中(先发酵法)和将蔬菜粉(或汁)加入肉馅中再发酵(后发酵法)两种生产方式,并对目前的研究现状、进展、存在问题及今后发展方向进行了论述,以期为生产安全腌肉制品提供借鉴。     

Changes in nitrate and nitrite content of four vegetables during storage at refrigerated and ambient temperatures

The nitrate and nitrite contents of four kinds of vegetables (spinach, crown daisy, organic Chinese spinach and organic non-heading Chinese cabbage) in Taiwan were determined during storage at both refrigerated (5 ± 1°C) and ambient temperatures (22 ± 1°C) for 7 days. During storage at ambient temperature, nitrate levels in the vegetables dropped significantly from the third day while nitrite levels increased dramatically from the fourth day of storage. However, refrigerated storage did not lead to changes in nitrate and nitrite levels in the vegetables over 7 days.     

不同贮藏蔬菜中亚硝酸盐变化的研究

本研究以大白菜、甘蓝、白萝卜为试验材料,研究了室温、低温、腌制三种贮藏蔬菜中亚硝酸盐含量的变化及其形成的机理。结果表明:室温、腌制两种贮藏方法的初期都出现“亚硝峰”。形成“亚硝峰”的原因依贮藏方法而异,室温贮藏蔬菜中“亚硝峰”的形成是由于采摘后菜体内硝酸还原酶的活性增强导致蔬菜内硝酸盐还原成亚硝酸盐;腌制贮藏蔬菜中“亚硝峰”的形成是由于发酵过程中杂菌所致。腌制菜中“亚硝峰”的峰值大大高于室温贮藏,并超过FAO/WUO规定的ADI值,腌制后期亚硝酸盐含量在安全食用范围。室温、低温贮藏蔬菜中亚硝酸盐含量的最高值小于ADI值,可以放心食用。     

紫外检测离子色谱法测定酱腌菜中的亚硝酸盐与硝酸盐

建立了紫外检测离子色谱法测定酱腌菜中的亚硝酸盐与硝酸盐的分析方法。样品经超声提取后,以1.8 mmol/L Na2CO3+1.7 mmol/L NaHCO3为流动相,经Metrosep A Supp 4-250阴离子交换色谱柱分离,于210nm处紫外检测。结果表明:此法NO2-、NO3-的检出限分别为1.0 mg/kg和2.0 mg/kg,实际样品的加标回收率分别为80.4%~82.1%和93.1%~96.5%,相对标准偏差≤10%。     

子午岭林区常见野生蔬菜硝酸盐、亚硝酸盐及维生素C含量的测定

测定了子午岭林区常见19种野生蔬菜中的硝酸盐、亚硝酸盐和维生素C的含量,比较蔬菜中硝酸盐分级评价标准和我国制定的无公害蔬菜亚硝酸盐限量标准及维生素C的含量发现,香椿硝酸盐含量处于安全水平,但亚硝酸盐含量高于我国制定的无公害蔬菜亚硝酸盐的限量标准,且维生素C含量小于50 mg/100g,不属于无公害蔬菜的范畴,建议少量食用或经过特殊处理后再食用;其余17种野生蔬菜均属于安全无公害蔬菜,且维生素C的含量高,可放心食用.     

Nitrate and nitrite quantification from cured meat and vegetables and their estimated dietary intake in Australians

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.     

Nitrate and nitrite in vegetables on the Danish market: content and intake

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.     

京郊主要蔬菜产品器官硝酸盐与亚硝酸盐含量分析与评价

对京郊52种蔬菜产品,以及同一种类不同品种、同一品种产品的不同部位的硝酸盐、亚硝酸盐和VC含量等进行测定。结果表明：供试蔬菜产品器官的硝酸盐含量在不同种类、品种及其不同部位间存在明显差异。以蔬菜鲜质量器官中硝酸盐含量均值计算,根菜类(420.66mg/kg)＞叶菜类(281.24mg/kg)＞茎菜类(279.54mg/kg)＞果菜类(176.54mg/kg)＞花菜类(157.93mg/kg);同种蔬菜品种间的硝酸盐含量相差1.13～5.48倍;产品器官不同部位的硝酸盐含量也有较大差异,如结球叶菜硝酸盐含量外叶＞中叶＞内叶,叶柄＞叶片,黄瓜果实顶部、基部＞中部,果肉＞果心,萝卜根皮＞根肉。各供试蔬菜产品器官的亚硝酸盐含量多在1mg/kg以下,个别蔬菜种类如茼蒿可达6.74mg/kg,不同蔬菜种类、品种和部位间亚硝酸盐含量差异不如硝酸盐含量差异明显。果菜类、叶菜类和花菜类蔬菜产品器官的VC含量普遍较高,如辣椒可达146.56mg/100g,但品种间VC含量差异不显著。由此可见,目前京郊蔬菜产品器官中的硝酸盐和亚硝酸盐含量多在安全范围内,但仍建议消费者科学合理进行蔬菜种类搭配以保障人体健康。