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几种常见野菜中硝酸盐和亚硝酸盐含量 总被引:4,自引:1,他引:4
几种常见野菜中硝酸盐和亚硝酸盐含量韩涛,马红梅,李丽萍,黄万荣北京农学院食品科学系102208近年来,野生蔬菜因其营养、保健、无污染等优点日益受到人们的关注。杨恩孚等人[1]曾具体分析过72种野菜中的维生素含量,其中胡萝卜素的含量只有7种低于胡萝卜;... 相似文献
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蔬菜中硝酸盐和亚硝酸盐的测定及含量分析 总被引:2,自引:0,他引:2
采用超声提取、活性炭柱脱色和微孔膜过滤等步骤对蔬菜进行预处理,离子色谱法测定蔬菜中硝酸盐和亚硝酸盐含量。探讨不同贮藏条件下4种蔬菜中硝酸盐和亚硝酸盐含量的变化情况。结果表明:无论常温贮藏还是低温贮藏,贮藏7d内,4种蔬菜中硝酸盐含量变化基本上是呈下降趋势,亚硝酸盐含量均呈现先急剧上升后近于平稳的趋势,但常温贮藏的亚硝酸盐含量高于低温贮藏,除韭菜外,其它蔬菜中亚硝酸盐含量均低于限量标准4mg/kg。 相似文献
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不同生长发育阶段几种野菜中硝酸盐、亚硝酸盐及维生素C的含量 总被引:1,自引:0,他引:1
测定了荠菜、泥胡菜和多头苦荬菜等3种野菜不同发育阶段叶中的硝酸盐、亚硝酸盐和维生素C的含量。参考蔬菜中硝酸盐含量分级评价标准,参考我国制定的无公害蔬菜亚硝酸盐含量限量标准(以NaNO2计≤4.0mg/kg),考虑到各种野菜的维生素C的含量,对这3种野菜评价如下:泥胡菜和多头苦荬菜的各个时期的叶,硝酸盐含量低于轻度污染水平444mg/kg,亚硝酸盐含量低于我国制定的无公害蔬菜亚硝酸盐含量的限量标准,所以,它们属于一级野菜,可以安全食用;果期荠菜的叶,硝酸盐含量低于807mg/kg,属于中度污染水平,亚硝酸盐含量低于我国制定的无公害蔬菜亚硝酸盐含量的限量标准,属二级蔬菜范围,不宜生食,煮熟或盐渍可安全食用:荠菜的期于各期叶的硝酸盐含量高于807mg/kg而低于1268mg/kg,亚硝酸盐含量低于我国制定的无公害蔬菜亚硝酸盐含量的限量标准,属于三级蔬菜,不可生食和盐渍,可熟食。 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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A rapid strong anion exchange HPLC/UV procedure has been developed for the determination of nitrate and nitrite in a wide variety of cured meats. The accuracy of this technique has been confirmed by the good agreement achieved with the existing British Standard colorimetric method. The applicability and repeatability of the procedure has been established in a survey of over 200 samples. The agreement between duplicate determinations and their respective means averaged +/- 3.4% for nitrite and +/- 4.3% for nitrate as defined by the term [(a - b)/(a + b)] X 100% where a and b are the repeat determination values. 相似文献
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Terence A. Roberts 《Journal of the science of food and agriculture》1975,26(11):1755-1760
In unheated products nitrite, together with sodium chloride and the pH value, contributes to the selection of the bacteria which grow during storage. Nitrate per se is generally believed to serve only as a reservoir for nitrite, but the commercial use of nitrate-free cover brines in the Wiltshire bacon industry shows that such a reservoir is not always essential. Nitrate sometimes reduced the growth rate of bacteria in experimental Wiltshire collar bacon, but was of no benefit in back bacon. The clostridia occurring naturally in the bacon grew to higher numbers in collar cured without nitrate than that cured with nitrate. Clostridium botlinum (types A and B) was detected in these bacons, but did not grow in the bacon. In heated products the growth of surviving bacteria is controlled by the interaction of several factors including pH, sodium chloride, storage temperature and sodium nitrite or a substance derived from it upon heating. Further experiments are warranted to investigate the effects of dextrose, nitrate, ascorbate and polyphosphate. 相似文献
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Nitrite and nitrate + nitrite can be determined by selective chemical reduction to nitric oxide which is measured using a chemiluminescence analyser. The reducing agents are sodium iodide in acetic acid for nitrite and ferrous ammonium sulphate-ammonium molybdate for nitrate + nitrite. The concentrations of the reducing agents have been optimized to obtain the maximum yield of nitric oxide and the minimum coefficient of variation. Under these conditions, it is possible to inject repeated samples into the refluxing reducing agents and to obtain rapid evolutions of nitric oxide from which the determinations can be made. Nitric oxide has also been produced using the nitrite reagents from organic nitrites, a S-nitrosothiol, a pseudonitrole and N-nitrosamines. Similarly, an organic nitrate and some C-nitroso compounds respond to the method for nitrate but only to the extent of a yield of nitric oxide of about 10% of the theoretical. Very low or zero responses were evident from aliphatic and aromatic C-nitro compounds but not omega-N-nitroarginine which gave a large yield of nitric oxide using the reagents for nitrate. In general, however, concentrations of nitrate will be in considerable excess of those of related compounds which would interfere with the determinations. Nitrate can be determined either by difference in its mixtures with nitrite or by prior removal of the nitrite using ascorbic acid provided oxygen and nitric oxide are removed by degassing with nitrogen. 相似文献
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The Nitrate content of foods may be determined by means of azo-dye coupling after reduction of the nitrate with the aid of active cadmium produced in the sample solution. An easy method for determining nitrite consists in the colorimetric estimation of a coloured chelate formed from nitrite, resorcinol and zirconium(IV) oxychloride. 相似文献
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抑制电导—离子色谱法同时测定肉制品中亚硝酸盐和硝酸盐 总被引:1,自引:0,他引:1
建立了一种灵敏、快速的同时测定肉制品中亚硝酸盐和硝酸盐的抑制电导-离子色谱分析方法。样品经超声提取后,以DIONEXIonPacAS19(4mm×250mm)色谱柱分离,用DIONEXEG40淋洗液发生器自动淋洗,采用梯度洗脱方式,以抑制电导检测器进行检测。实验表明,硝酸盐和亚硝酸盐的方法检出限(3S/N)为0.6mg/kg和0.8mg/kg,在0.1~50μg/mL范围内呈良好线性关系,相关系数分别为0.9994和0.9989,回收率为98.4%和96.5%,重复性(RSD)为2.8%和3.2%。本方法灵敏度高,重复性好,可用于肉制品中的亚硝酸盐和硝酸盐的检测。 相似文献
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Peter F. Swann 《Journal of the science of food and agriculture》1975,26(11):1761-1770
Nitrate is essentially non-toxic to mammals but it can be reduced to nitrite either in improperly stored food, in the rumen of cattle, in the gastrointestinal tract of the human infant, and by the microflora of the human mouth. The nitrite from these and other sources, including that purposely added to food, presents a toxic hazard both because of the direct toxicity of nitrite, and by the formation of carcinogenic N-nitroso compound by reaction with amino compounds. Administration of toxic amounts of nitrite induces methaemoglobinaemia. The nature of this disease, its importance in human medicine and the reason for the particular sensitivity of the infant, are briefly discussed. The carcinogenic properties of N-nitroso compounds are described. These compounds have been found in the environment and may be formed in the stomach from amines and nitrite. Our knowledge of the amount of N-nitroso compounds to which man is exposed, is continually increasing but with the lack of epidemiologic evidence, the assessment of the significance to man of these traces of N-nitroso compounds depends upon the interpretation of animal experiments and their extrapolation to man. This extrapolation would be more certain if there were a more clear understanding of the factors determining tissue selectivity by carcinogens and tissue sensitivity, and of the mechanism of cumulation of carcinogenic doses and of synergism between carcinogens. Recent experiments suggest that there may soon be a significant breakthrough in the understanding of this. These experiments are briefly discussed. 相似文献