稳定性肥料在榨菜上的应用效果研究

探究稳定性肥料在榨菜上的应用效果,实验结果表明,稳定性肥料不仅可以一次性施肥全生长季持久供肥,而且可有效降低榨菜中硝酸盐和亚硝酸盐含量,提高榨菜产量,提升榨菜品质。     

壳聚糖对食品中亚硝酸盐的消除作用

采用紫外-可见分光光度法测定了壳聚糖对榨菜和香肠中亚硝酸盐的清除率,考察了影响壳聚糖清除亚硝酸盐的因素(壳聚糖用量、消除温度及消除时间),最终确定了壳聚糖对香肠及榨菜中亚硝酸盐的最佳消除率的条件,消除率可以达到81.09%和89.26%。并对消除效果的差别做了初步的分析,为生产加工食品过程中添加过亚硝酸盐的食品中亚硝酸盐的消除提供一定的理论基础。     

食品中亚硝酸盐含量的测定

样品经沉淀蛋白质、除去脂肪,在弱酸性溶液中亚硝酸盐与对氨基苯磺酸重氮化后,再与盐酸萘乙二胺偶联生成紫红色的偶氮染料,用分光度法测定。经过校正,亚硝酸盐含量x（ug）与吸光度A之间在λmax=550nm处,具有良好的线性关系,在亚硝酸盐的量为0～25μg／25mL水溶液中,服从朗伯-比耳定律,其线性方程为A=0．0132蜀相关系数r^2=0．9982,利用此方法所测定的当地出售的部分食品中亚硝酸盐的含量均未超过相关标准。用分光光度法测定腌制蔬菜中亚硝酸的含量,方法简单、方便、快捷、实用。     

不同洗涤、烹饪方式对蔬菜中亚硝酸盐含量的影响

目的:研究不同洗涤、烹饪方式对蔬菜中亚硝酸盐含量的影响,从而对人们科学饮食给予一定的指导。方法:经过实验方案选择的几种洗涤方法和烹饪方法处理蔬菜后,用紫外分光光度法测定蔬菜中亚硝酸盐含量。结果:未经处理的蔬菜中,叶菜类蔬菜亚硝酸盐含量较高,根茎类、瓜果类亚硝酸盐含量较低。不同洗涤方式对亚硝酸盐的去除效果不同,果蔬洗涤剂清洗过的蔬菜亚硝酸盐含量降低较为明显,1%NaCl溶液清洗过的蔬菜亚硝酸盐含量略有降低,去离子水清洗过的蔬菜亚硝酸盐含量变化不大。不同烹饪方法对亚硝酸盐含量的影响不同,炒制较生食略有降低但整体变化不大;水烫后根茎类、瓜果类蔬菜亚硝酸盐含量降低,叶菜类亚硝酸盐含量升高;腌制后各类蔬菜亚硝酸盐含量普遍大幅度升高。结论:建议消费者多种蔬菜搭配食用,烹饪前可采用合理方式清洗,不过量食用腌制蔬菜,以减少亚硝酸盐的摄入。     

自来水中亚硝酸盐含量的检测和处理研究

亚硝酸盐对人体的健康有着重要的影响,研究水中亚硝酸盐的含量和消除方法具有重要的意义,本文以国标的方法绘制亚硝酸盐标准工作曲线,检测衢州地区自来水中亚硝酸盐的含量,并试验次氯酸钠对自来水中亚硝酸盐的消除作用。     

市售酱腌菜和肉制品中亚硝酸盐含量测定及安全性评价

通过分光光度法测定市售酱腌菜和肉制品中亚硝酸盐的含量,以此分析贵州省内市场上酱腌菜和肉制品的食品安全状况。测定结果表明:20批次样品中亚硝酸盐含量存在一定的差异,市售酱腌菜10批次中亚硝酸盐含量为1.02~13.68 mg/kg,低于国家限量标准20 mg/kg,市售肉制品10批次中亚硝酸盐含量为2.16~14.39 mg/kg,低于国家限量标准30 mg/kg。研究结果表明:适量食用酱腌菜和肉制品均不会影响人体健康。     

食品中亚硝酸盐的测定方法研究进展

亚硝酸盐作为护色剂、防腐剂广泛用于食品加工中,但亚硝酸盐同时具有较强的致癌作用,过量食用会对人体的健康产生威胁和危害,国家食品标准对不同食品中亚硝酸盐含量有不同的规定。在食品加工中需严格控制亚硝酸盐的加入量。本文就食品中亚硝酸盐含量的测定方法及其研究进展进行综述。     

分光光度法测定饮料中亚硝酸盐的含量

本文采用分光光度法测定了软饮料中亚硝酸盐的含量。测定条件为538nm波长处加对氨基苯磺酸4. 0mL,盐酸萘乙二胺2. 0mL,显色时间为15min。标准曲线为A=0. 0390x+0. 0114。结果表明:农夫山泉、雪碧、优酸乳、冰红茶和橙汁样品中亚硝酸盐的含量分别为0. 0092,0. 0431,0. 0427,0. 0466,0. 0498μg·g~(-1)。     

离子色谱法测定奶粉中亚硝酸盐含量的优化

严格依据GB 5009.33-2016~([1])《食品安全国家标准食品中亚硝酸盐与硝酸盐测定》第一法离子色谱法测定奶粉中亚硝酸盐含量,回收率和准确率较低,通过研究比较不同的前处理方法,建立了采用C_(18)柱进行净化前处理,用紫外检测器检测奶粉中亚硝酸盐含量的离子色谱法。回归方程为y=1.7253x-0.0037,相关系数r=0.9997,RSD=4.65%,其加标回收率为91.7%～97.5%,提高了奶粉中亚硝酸盐的准确性。     

分光光度法测定速食面中亚硝酸盐的含量

实验采用分光光度法测定六种市售速食面中的亚硝酸盐的含量。在最大吸收波长为538 nm时,通过实验可知亚硝酸盐的含量与吸光度的关系方程为A=0.0144c+0.0019,它的相关系数为r2=0.9992。依据实验数据可得所测速食面的亚硝酸盐含量为9.61～15.09μg/g,回收率在96.1%～101.7%之间。根据实验结果分析几种被测速食面中亚硝酸盐含量符合食品添加剂国家安全标准规定。     

佛山市顺德新城区降水中污染物的监测和分析

为掌握佛山市顺德新城区降水中污染物的情况,2015年7月至8月,文章作者分别在雨天进行了降水取样,对降水中的pH、电导率、常见阴离子(F-、Cl~-、NO_3~(2-)、SO_4~(2-))及部分重金属(铅和镉)进行监测分析。选择有相关数据的珠江三角洲和石家庄、厦门等地的降水中污染物的情况进行对比。结果表明,顺德新城区降水中的p H和部分阴离子浓度优于珠江三角洲平均值,酸雨类型属于硫酸和硝酸混合型;其水体洁净程度略差于石家庄;铅和镉的浓度也高于厦门,甚至部分超出了人体能直接接触的安全范围。     

Metabolism of trideuterated iso-lignoceric acid in rats in Vivo and in human fibroblasts in culture

Saturated very long chain fatty acids (fatty acids with greater than 22 carbon atoms; VLCFA) accumulate in peroxisomal disorders, but there is little information on their turnover in patients. To determine the suitability of using stable isotope-labeled VLCFA in patients with these disorders, the metabolism of 22-methyl[23,23,23-²H₃]tricosanoic (iso-lignoceric) acid was studied in rats in vivo and in human skin fibroblasts in culture. The deuterated iso-VLCFA was degraded to the corresponding 16- and 18-carbon iso-fatty acids by rats in vivo and by normal human skin fibroblasts in culture, but there was little or no degradation in peroxisome-deficient (Zellweger’s syndrome) fibroblasts, indicating that its oxidation was peroxisomal. Neither the 14-, 20-, and 22-carbon iso-fatty acids nor the corresponding odd-chain metabolites could be detected. In the rat, the organ containing most of the iso-lignoceric acid, and its breakdown products, was the liver, whereas negligible amounts were detected in the brain, suggesting that little of the fatty acid crossed the blood-brain barrier. Our data indicate that VLCFA labeled with deuterium at the ω-position of the carbon chain are suitable derivatives for the in vivo investigation of patients with defects in peroxisomal β-oxidation because they are metabolized by the same pathways as the corresponding n-VLCFA. Moreover, as iso-VLCFA and their β-oxidation products are readily separated from the corresponding n-fatty acids by normal chromatographic procedures, the turnover of VLCFA can be more precisely measured. A preliminary report of part of this work (Reference 18) was presented at the 5th International Symposium on the Synthesis and Applications of Isotopes and Isotopically Labelled Compounds, Strasbourg, France, June 20–24, 1994.     

高效液相色谱法分析化妆品中微量成分的研究进展

综述了高效液相色谱法在化妆品中防腐剂、防晒剂中紫外线吸收剂以及性激素的检测等几个方面的应用;同时,介绍了分析所用的色谱柱、流动相、使用的检测手段以及样品的提取方法;最后针对目前存在的问题,提出了高效液相色谱用于化妆品中微量成分分析的研究方向和发展前景。     

Denitrification in shallow groundwater in a coastal agricultural area in Japan

In a coastal agricultural area in the central part of Japan (Shizuoka), we found decreasing nitrate concentration with depth in a shallow groundwater, where the depth to water table varied between 0.6 and 1.2 m below ground surface. High nitrate concentrations (5–29 mg N L^–1) were often observed in the upper layer (0–2 m) of the groundwater, but the concentration decreased to less than 1 mg N L^–1 in the deeper layer. Ammonium was scarcely detected, and the concentration of dissolved oxygen was usually low (< 1 mgO₂ L^–1) in the groundwater. Nitrate in the groundwater often had very heavy nitrogen stable isotope ratios (>20{}). There was a negative relationship between nitrogen stable isotope ratio of nitrate and its concentration. When nitrate was injected into the groundwater with acetylene and bromide (a conservative tracer), nitrate concentration decreased to 20% of the initial level within 5 days, accompanied by the increase in nitrite and nitrous oxide concentration and a little change in bromide concentration. These results indicate that microbial denitrification plays a potential role in the decrease of nitrate in shallow groundwater at the study site.     

我国硝酸工业生产技术新进展

系统叙述了我国硝酸工业2000-2007年生产现状及主要技术成果,尤其指出了国产"四合一"机组的成功投运,使我国硝酸国产化装置取得较大的进步,表现在吨酸的铂耗、氨耗和能耗等方面接近国外引进装置水平,同时介绍了国外双加压法硝酸生产技术的进展.我国已成为硝酸生产大国,仍需以先进的技术改造和发展我国硝酸工业,确保我国硝酸工业健康有序地发展,加快从硝酸生产大国向强国迈进的步伐.