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）     

Values of nitrate and nitrite in selected vegetables and potatoes cultivated in the region of Pu?aw]

Nitrate and nitrite contents were determined in selected vegetables and potatoes from plantations of individuals farmers, situated either in the vicinity of the Nitrogen Plant in Pu?awy or at a distance from this plant (control). Vegetables and potatoes both newly harvested and stored for 4 months in cellars were analysed. From farms selected by lot, samples of lettuce, cabbage, sauerkraut, beets, carrots and potatoes (all harvested in 1986 and 1987) were collected. Nitrate and nitrite contents were determined in 1215 plant samples. Nitrates were reduced on a cadmium column to nitrites, whereupon they were determined colorimetrically using sulphanilic acid and N-1-naphthylethylenediamine. This results showed that the nitrate contents are higher in the vegetables and potatoes cultivated in the region of the Nitrogen Plant, as compared with those from the Janowiec village distant from this plant (control). Differences in mean nitrate contents per 100 g dry matter were in years 1986 and 1987 for: lettuce 73%, 36%; cabbage 54%, 39%; beets 16%, 20%; carrots 51%, 29%; potatoes 77%, 36%, respectively. Moreover, the vegetables and potatoes grown in the region of the Nitrogen Plant, as compared with the control vegetables from the village located at a distance from this plant, displayed a greater percentage of samples with plants characterized by higher nitrate contents. The greater percentage of samples containing high nitrate levels, as well as the higher mean nitrate contents in vegetables and potatoes testify to the effect of the Nitrogen Plant on nitrate concentrations in the crops. In vegetables from both regions, the nitrite contents did not exceed 1 mg NaNO2/kg.(ABSTRACT TRUNCATED AT 250 WORDS)     

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。     

Effects of some processing methods on nitrate and nitrite changes in cruciferous vegetables

Changes in nitrate and nitrite content in selected cruciferous vegetables, resulting from blanching, boiling, freezing, frozen storage and boiling after previous freezing, were analyzed. The highest level of nitrate was detected in curly kale (302.0 mg/kg) and the lowest in green cauliflower (61.0 mg/kg). As for nitrite, the respective levels were found in white cauliflower (3.49 mg/kg) and green cauliflower (1.47 mg/kg). Both blanching and boiling of the cruciferous vegetables caused a considerable decrease in the total nitrate content, but at the same time no explicit changes were noted regarding the level of nitrite. In the vegetables stored frozen for 48 h, previously blanched, either an increase or no change was observed in the nitrate level, with the changes in the nitrite level being irregular. In the vegetables stored frozen for 4 months, previously blanched, generally a decrease was noted in the nitrate, and an increase in the nitrite level compared to the levels in the blanched vegetables. Boiling of the frozen vegetables (stored frozen for 48 h) most frequently caused a considerable reduction of the nitrate level in comparison to the content in the raw frozen vegetables. No changes were observed resulting from the boiling of the vegetables previously stored frozen for 4 months. Simultaneously, no explicit changes were found regarding the nitrite level in the frozen vegetable after boiling.     

Effect of Cultivar and Harvest Date on Nitrate (NO3) and Nitrite (NO2) Content of Selected Vegetables Grown Under Open Field and Greenhouse Conditions in Jordan

Two cultivars each of spinach, lettuce, cabbage, squash, and cauliflowers, as well as one cultivar of parsley were grown in open fields. In addition, two cultivars each of squash, cucumber, and tomatoes were grown in polypropylene-covered greenhouses. The effects of cultivar and harvest date on the nitrate and nitrite content of the edible parts of these vegetables were studied. Harvest date was found to have a significant effect (P≤0.05) on the nitrate content of the open-field-grown spinach, cabbage, and squash, and the nitrite content of the open-field-grown spinach, lettuce, and cabbage. Late-harvested vegetables had the lowest nitrate levels, while the pattern of their nitrite content was irregular with respect to the dates that gave highest nitrite levels in each vegetable. Harvest date had no significant effect on either nitrate or nitrite content of the greenhouse-grown vegetables.Cultivar had a significant effect (P≤0.05) only on the nitrate content of the greenhouse-grown tomatoes and squash, while it had no effect on either the nitrate or the nitrite content of all other vegetables irrespective of their cultivation method, although their levels in the greenhouse-grown vegetables were higher than those grown in open fields. Nitrate levels in these vegetables were generally low (lowest average of 0.13 mg 100 g⁻¹in open-field-grown cauliflower, and highest of 4.77 mg 100 g⁻¹in greenhouse-grown squash). Nitrite levels, on the other hand, were similar to those reported elsewhere in the world, ranging from non-detectable levels in open-field-grown cauliflower, to a maximum level of 0.43 mg 100 g⁻¹in greenhouse-grown squash.A highly significant, although low, positive correlation (r=0.55, P≤0.01, n=108) was found between nitrate and nitrite contents of the greenhouse-grown vegetables, compared to a non-significant, and much lower correlation between the two variables in the open-field-grown vegetables.     

Geographic distribution of liver and stomach cancers in Thailand in relation to estimated dietary intake of nitrate, nitrite, and nitrosodimethylamine

It is our working hypothesis that the high rate of the liver and gastric cancers in North and Northeast Thailand is associated with increased daily dietary intake of nitrate, nitrite, and nitrosodimethylamine (NDMA). Samples of fresh and preserved Thai foods were systematically collected and analyzed from 1988 to 1996 and from 1998 to 2005. Consumption frequencies of various food items were determined on the basis of a dietary questionnaire given to 467 adults (212 males and 255 females) from 1998 to 2005. Food consumption data for the preceding and current year were collected and intakes (day, week, and month) of nitrate, nitrite, and NDMA were calculated. The trends in liver and stomach cancer age-standardized incidence rates (ASR) in four regions of Thailand were compared with the dietary intake of nitrate, nitrite, and NDMA in those same geographic regions. Mean daily intakes of nitrate of 155.7 mg/kg, of nitrite of 7.1 mg/kg, and of NDMA of 1.08 microg/kg per day were found. Significant differences in dietary nitrate, nitrite, and NDMA intakes were seen between various Thai regions (P < 0.0001), and these corresponded to the variations in liver and stomach cancer ASR values between the regions. Dietary factors are likely to play key roles in different stages of liver and stomach carcinogenesis in Thailand.     

Geographic Distribution of Liver and Stomach Cancers in Thailand in Relation to Estimated Dietary Intake of Nitrate,Nitrite, and Nitrosodimethylamine

It is our working hypothesis that the high rate of the liver and gastric cancers in North and Northeast Thailand is associated with increased daily dietary intake of nitrate, nitrite, and nitrosodimethylamine (NDMA). Samples of fresh and preserved Thai foods were systematically collected and analyzed from 1988 to 1996 and from 1998 to 2005. Consumption frequencies of various food items were determined on the basis of a dietary questionnaire given to 467 adults (212 males and 255 females) from 1998 to 2005. Food consumption data for the preceding and current year were collected and intakes (day, week, and month) of nitrate, nitrite, and NDMA were calculated. The trends in liver and stomach cancer age-standardized incidence rates (ASR) in four regions of Thailand were compared with the dietary intake of nitrate, nitrite, and NDMA in those same geographic regions. Mean daily intakes of nitrate of 155.7 mg/kg, of nitrite of 7.1 mg/kg, and of NDMA of 1.08 μ g/kg per day were found. Significant differences in dietary nitrate, nitrite, and NDMA intakes were seen between various Thai regions (P < 0.0001), and these corresponded to the variations in liver and stomach cancer ASR values between the regions. Dietary factors are likely to play key roles in different stages of liver and stomach carcinogenesis in Thailand.     

济南市蔬菜中硝酸盐及重金属污染

目的 了解济南市蔬菜中硝酸盐和重金属含量。方法 于2003年在济南市主要蔬菜基地采集17种蔬菜样品采用紫外分光光度法测定硝酸盐含量,同时采集8种蔬菜样品采用原子吸收光谱法测定重金属(铅、镉、铜、锌)含量,并根据GB18406—2001进行评价。结果 17种蔬菜中硝酸盐含量最高的为芹菜(4895mg／kg),最低的为西红柿(23mg／kg),平均为1074mg／kg。8种蔬菜中铅、镉、铜、锌的含量分别为：0．007-0．037、0．002-0．033、0．28-2．00、0．39-3．80mg／kg。叶菜类中芹菜和小白菜硝酸盐含量超标率分别为100％和22％,其余均未超标;根茎类中萝卜硝酸盐含量超标33％,藕未超标;瓜果类中芸豆、菜花、茄子、豆角硝酸盐含量超标率分别为100％,40％,33％,8％,其余均未超标。绿叶菜类和根茎类重金属含量普遍高于瓜果类,8种蔬菜中重金属含量均未超出无公害蔬菜限量标准。结论 济南市蔬菜中硝酸盐污染应引起重视。     

食品中亚硝酸盐允许限量的研究

依据我国食品中亚硝酸盐的含量及ＡＤＩ值和毒理学有关内容提出食品中亚硝酸盐允许限量的卫生标准为：粮食（大米、面粉和玉米）３ｍｇ／ｋｇ；蔬菜４ｍｇ／ｋｇ；鲜鱼类３ｍｇ／ｋｇ；鲜肉类３ｍｇ／ｋｇ；鲜蛋类５ｍｇ／ｋｇ；酱腌菜２０ｍｇ／ｋｇ；奶粉２ｍｇ／ｋｇ和精盐２ｍｇ／ｋｇ。     

Nitrite and nitrate content of meat and sausage products in the Republic of Cuba

283 samples of meat and sausages made from pork from the Meat-Works Colombia in the Country of Las Tunas--Republic of Cuba--have been analysed on their contents of nitrite and nitrate. On an average the investigated quantities lie much below the present tolerance limit in Cuba (125 mg/kg nitrite and 500 mg/kg nitrate). The authors recommend to lower the tolerance limit for nitrate in meat and sausages to 300 mg/kg.     

Residual nitrite and nitrate content in French cooked hams and shoulders]

The test laboratory of the "Centre technique de la salaison, de la charcuterie et des conserves de viandes" has evaluated the nitrite and nitrate salts contents of 1 468 cooked hams and shoulders. 90,5 p. 100 of sample have a sodium nitrite content of less than 150 mg/kg. 81,5 p. 100 have a potassium nitrate content of less than 500 mg/kg. The measured contents show a wide scattering. The nitrite mean content is of 61 mg/kg with a standard deviation of 95. The nitrate mean content is of 292 mg/kg with a standard deviation of 382. There were no significant variations between the various categories of cooked hams and shoulders.     

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.     

Assessment of nitrate,nitrite and chloride in selected cured meat products and their exposure to school children in Brunei Darussalam

The readily available, good taste and easy to prepare cured meat products have become a prominent feature in children’s diet, leading to possible overconsumption of certain food additives. In this study, amount of nitrite, nitrate and salt, with mean values of 12.8 mg/kg, 20.2 mg/kg and 0.94 g/100 g, respectively and their intake from consumption of cured meat products (sausages, salamis, meatloaves and meatballs), were estimated for 2339 school children. The estimated salt intake for overall children was 0.53–1.01 g/day, where none of the children’s salt intake exceeded their age group’s Tolerable Upper Intake level. While the average estimated intake of nitrate and nitrite were at 0.08 mg/kg b.w/day and 0.05 mg/kg b.w/day, respectively. Based on the above estimation, ∼20% of the total children exceeded the Acceptable Daily Intake (ADI) of nitrite of 0.07 mg/kg b.w/day while none of the children exceeded the ADI of nitrate of 3.7 mg/kg b.w/day.     

Nitrate levels in edible wild herbs and vegetables common in Jordan

Forty six selected species of wild edible herbs and vegetables common in Jordan were collected from their natural growing places; twelve of them were collected from more than one location. The nitrate contents of the edible parts, and in some cases non-edible parts, were determined using the cadmium reduction method. The nitrate level varied widely ranging from 29 mg/kg in the leaves of tetragonolbus (Tetragonolobus Palaestinus) to 6743 mg/kg in star fenugreek (Trigonella Stellata). With the exception of the families of Araceae and Cruciferae, there was a wide variation in the nitrate concentrations within the species of each family. In general, the nitrate content of the stems was higher than that of the leaves which in turn was higher than that of the roots and bulbs. The same species collected from irrigated (presumably fertilized) farms were generally of higher nitrate content than those collected from pasture, forest or non-irrigated farms. However, many of the studied plants remain of relatively high nitrate content regardless of where they were grown.     

Changes in nitrate levels and nitrates in carrot roots during storage in an earthen clamp]

The aim of this study was the determine the nitrate and nitrite contents in edible parts of 5 varieties of carrot, before clamping and after uncovering, in fresh carrot and dry matter. The colorimetric methods of Griess with modified by Romminger and Straus were used. Dry matter was determined with a drier. Statistical significance of differences in the levels of the studied compounds was calculated by a two-ways analysis of variance. In the studied carrot before clamping average 406.6 mg KNO3/kg and 4.1 mg NaNO2/kg of fresh product was found. These amounts considerably admissible values. After 6-month storage a statistically significant decrease in nitrate levels of Karlena, Perfekcja and Amager was found, in dry matter, whereas a statistically significant increase in Koral variety, while no statistically significant difference in the nitrate level did not changes, was found in Bercoro variety. As concerns nitrites a statistically significant decrease was stated in all carrot varieties.     

A Nitrate-Rich Vegetable Intervention Elevates Plasma Nitrate and Nitrite Concentrations and Reduces Blood Pressure in Healthy Young Adults

BackgroundEmerging evidence suggests that increasing dietary nitrate intake may be an effective approach to reduce blood pressure. Beetroot juice is often used to supplement dietary nitrate, whereas nitrate intake levels from habitual diet are low. An increase in the habitual intake of nitrate-rich vegetables may represent an alternative to nitrate supplementation. However, the effectiveness and acceptability of a nitrate–rich-vegetables diet remain to be established.ObjectiveThe aim was to investigate the effect and feasibility of two different intervention strategies to increase dietary nitrate intake, on plasma nitrate/nitrite concentrations and blood pressure.DesignA randomized, crossover trial was used.ParticipantsParticipants were healthy men and women (both n=15; age: 24±6 years) from the Netherlands.InterventionParticipants were instructed to consume ∼400 mg nitrate at lunch, provided through nitrate-rich vegetables and dietary counseling, or beetroot juice supplementation. Both interventions lasted 1 week, with 1-week washout (January to April 2017).Main outcomePlasma nitrate and nitrite concentrations and resting systolic and diastolic blood pressure were measured in an overnight fasted state (before and after intervention) and ∼2.5 hours after lunch (before and throughout intervention on day 1, 4, and 7).Statistical analysisTwo-factor (time × treatment) repeated-measures analyses of variance were performed.ResultsMean plasma nitrate concentrations increased with both interventions, with a larger increase in beetroot juice vs nitrate-rich vegetables, both in a fasted state and ∼2.5 hours after lunch (day 1, beetroot juice: 2.31±0.56 mg/dL [373±90 μmol/L] vs nitrate-rich vegetables: 1.71±0.83 mg/dL [277±134 μmol/L]; P<0.001). Likewise, mean plasma nitrite concentrations increased with both interventions, but were higher after lunch in beetroot juice than in nitrate-rich vegetables (day 1: 2.58±1.52 μg/dL [560±331 nmol/L] vs 2.15±1.21 μg/dL [468±263 nmol/L]; P=0.020). Fasting mean systolic and diastolic blood pressure did not change, but mean systolic and diastolic blood pressure assessed ∼2.5 hours after lunch were significantly reduced throughout both intervention periods (P<0.05), with no differences between beetroot juice and nitrate-rich vegetables (day 1, systolic blood pressure: –5.1±9.5 mm Hg and diastolic blood pressure: –5.3±8.9 mm Hg).ConclusionShort-term consumption of dietary nitrate in the form of nitrate-rich vegetables represents an effective means to increase plasma nitrate and nitrite concentrations, and reduces blood pressure to the same extent as beetroot juice supplementation.     

江西省居民日常食用蔬菜中氯酸盐和高氯酸盐污染调查

目的 了解江西省居民日常食用蔬菜中氯酸盐和高氯酸盐污染现状。方法 在江西省11个设区市随机采集128份蔬菜样品,采用超高效液相色谱-串联质谱法测定氯酸盐和高氯酸盐含量,并对检测结果进行分析。结果 蔬菜中氯酸盐的检出率为53.9%,含量范围为ND～0.071 7 mg/kg,平均检测值为0.010 9 mg/kg。块根块茎类为0.018 5 mg/kg、鲜豆类为0.018 3 mg/kg、叶菜类蔬菜为0.012 2 mg/kg,氯酸盐平均检测值较高。蔬菜中高氯酸盐的检出率为94.5%,含量范围为ND～2.184 7 mg/kg,平均检测值为0.121 1 mg/kg。叶菜类蔬菜高氯酸盐含量最高。结论 江西省居民日常食用蔬菜中氯酸盐有部分检出但总体污染程度较低。高氯酸盐的检出率和污染程度较高,根据欧盟蔬菜高氯酸盐限量值判定,其超标率为18%,存在一定健康风险,应引起重视。     

山西省出生缺陷高发区居民饮水中硝酸盐和亚硝酸盐含量研究

目的了解山西省出生缺陷高发地区饮水中硝酸盐和亚硝酸盐含量。方法选择山西省太原市、太谷县和平定县作为研究现场,采集当地居民不同类型的饮用水测定硝酸盐和亚硝酸盐含量。结果研究地区饮水中硝酸盐平均含量为3·5mg/L,有4·0%的样品超过我国的饮用水卫生标准。井水中的硝酸盐含量(5·1mg/L)高于自来水(2·7mg/L)。饮水中亚硝酸盐平均含量为0·004mg/L,以泉水含量最高(0·015mg/L)。结论研究地区居民饮水中硝酸盐和亚硝酸盐含量并没有显著高于文献报道的其它地区。饮水中硝酸盐和亚硝酸盐暴露在山西省出生缺陷高发中的作用可能不大。     

Dietary fat and N-nitrosation in the rat

1. Groups of four conventional (CV) rats ate natural or purified diets either with or without 100 g fat/kg and drank 0.235 M-sodium nitrate. The fats tested were butterfat, coconut oil, olive oil, maize oil and safflower oil. 2. Decreased urinary excretion of N-nitrosoproline (NPRO) was observed in rats fed on fat-supplemented diets compared with those fed on low-fat diets, with butterfat having the greatest effect of the fats tested. 3. Reduced excretion of NPRO was not the result of inhibition of the intragastric N-nitrosation reaction or absorption of nitrosamine from the gastrointestinal tract. 4. The availability of nitrite in aqueous solution was decreased by the fat diets but the effect was similar in all the fats tested. 5. Nitrate reductase activity was present in the forestomach contents of CV rats at pH greater than 4 and was apparently inhibited by feeding a fat diet. No nitrate reductase activity was detected in stomach contents of germ-free rats. 6. Nitrate reductase activity in stomach and small intestinal tissue was not altered by feeding a fat diet. 7. It was concluded that nitrate reductase activity in stomach contents was of microbial origin and the decreased urinary excretion of NPRO on feeding the fat diets was mainly due to the inhibition of nitrate reductase activity in stomach contents.     

The Physico-Chemical Characteristics and Some Nutritional Values of Vegetable Amaranth Sold in Nairobi-Kenya

Twenty one major supermarkets and ten independent green grocers in the city of Nairobi were surveyed for types of vegetable amaranths sold and their post harvest handling. The nutrient composition of the vegetables was also analyzed. In addition, information on three other traditional leafy vegetables (TLVs) namely, Cleome gynandra, Solanum nigrum, and Vigna unguiculata was obtained. All the vegetables were sold in bundles of average weight 0.45 kg. The edible fraction per bundle averaged 38.9%. Chemical analyses showed that vegetable amaranth had a moisture content of 85.5%, therefore a dry matter content of 14.5%. Expressed on dry matter basis, the mean total ash content was 19.2%, crude protein content 26.1% and the crude fiber content 14.7%. The mean ascorbic acid content was 627 mg/100 g, zinc content 5.5m g/100 g and iron content 18 mg/100 g. The men nitrate content was 732.5 mg/100 g, total oxalates 5830 mg/100 g and soluble oxalates 3650 mg/100 g, while the lead content averaged 1.03 mg/100 g. The study concludes that vegetable amaranth has potential as popular vegetable in the diets of Kenyans to significantly contribute to provision of micronutrients, particularly iron and zinc.