催化流动注射光度法检测制革废水中的亚硝酸盐

研究了催化流动注射光度法检测制革废水中的亚硝酸盐的新方法。考察了检测波长、反应圈长度、进样体积、流速、显色试剂对实验的影响并确定了最佳实验条件:检测波长为610 nm,反应圈长度为5 m,进样体积为450μL,样品和推动液流速为0.40 mL/min,显色液流速为0.27 mL/min,显色液中孔雀石绿浓度为3.0×10-5mol/L。在优化的流动注射条件下,系统的线性范围为2.0～160.0μg/L,连续16次平行检测的相对标准偏差(RSD)为0.79%,检测限为0.3μg/L。该方法可用于皮革废水中痕量亚硝酸盐的检测,加标回收率为97.6～103.4%。     

大豆分离蛋白中的亚硝酸盐超声辅助提取分析方法的研究

大豆分离蛋白在肉制品、乳制品和面制品等食品中都具有广泛的应用,是一类重要的食品配料,因此其安全问题十分重要。而亚硝酸盐含量是食品安全控制的重要内容,作为配料的大豆分离蛋白是否含有亚硝酸盐以及亚硝酸盐的含量水平应该得到重视。实验发现,使用国标法中的分光光度法测定大豆分离蛋白中亚硝酸盐的含量,回收率较低,不到80%,这样会造成测定的不准确,不利于亚硝酸盐的含量监控。因此本研究利用超声波400W辅助提取,省去了样品于沸水浴中加热15min的步骤,对大豆分离蛋白中亚硝酸盐含量进行测定。实验结果表明,改进后的大豆分离蛋白亚硝酸盐超声波辅助提取方法回收率高(97.2%)、精密度好(相对标准偏差为2.5%),适合大豆分离蛋白中亚硝酸盐的测定。     

新会陈皮保健泡菜的试制及评价

目的 在日常泡菜腌制过程中, 亚硝酸盐含量的控制一直是泡菜发酵中的关键问题。本文基于“药食同源”概理念概念, 以结合广东地理标志产品新会陈皮 为原辅料, 试制添加新会陈皮的保健泡菜, 并评价其保健功效。方法 选择在室温下自然发酵, 探究不同盐浓度条件、不同陈皮添加量对泡菜腌制过程中对产生亚硝酸盐含量的影响, ,对泡菜进行色泽、脆度和风味等感官评价, ,并分别测定陈皮泡菜清除羟基自由基和DPPH自由基和羟基自由基的能力。结果 试制保健泡菜中的亚硝酸盐含量 与盐浓度相关,6%盐浓度较适宜,高盐浓度会导致亚硝酸盐抑制率下降;添加陈皮的保健泡菜可显著降低亚硝酸盐峰值含量,其中2%陈皮添加量降低最显著,同时添加陈皮的保健泡菜对DPPH自由基和羟基自由基具有明显的清除效果。结合上述实验结果及感官评价可知盐浓度6%、陈皮添加量2%时评分较高,风味口感佳。结论 制作陈皮保健泡菜不仅可显著抑制亚硝酸盐产生,提高抗氧化活性,且丰富泡菜的感官风味水平, 提升泡菜的品质, 延伸陈皮产业链。     

西瓜豆瓣酱研制及其亚硝酸盐含量研究

首先在传统西瓜豆瓣酱制作的工艺基础上,设定西瓜、花生油的添加量为150,10 g,通过将影响西瓜豆瓣酱风味的主要因素豆曲、盐、花椒、八角、小茴香、葱、姜、蒜的添加量进行单因素和正交试验,确定自制西瓜豆瓣酱的较优配方。试验结果表明,西瓜150 g、豆曲30 g、盐10 g、花椒1 g、八角2 g、小茴香1 g、葱8 g、姜12 g、蒜8 g为最佳配方。另外,研究了西瓜与豆曲的比例对亚硝酸盐的影响及西瓜豆瓣酱发酵成熟后随放置时间增加亚硝酸盐含量的变化。研究表明,在相同食盐添加量下,亚硝酸盐含量随着西瓜添加量的下降而降低,自制豆瓣酱亚硝酸盐含量随着放置时间的增加而降低并逐渐接近于平稳。根据GB 2762-2017《食品安全国家标准食品中污染物限量》对于蔬菜类食品规定亚硝酸盐含量不得超过20 mg/kg[1],食用不会对人体产生危害,为人们在加工西瓜豆瓣酱时提供了参考。     

蔬菜腌渍发酵乳酸菌剂的研究

初筛出了适合生产发酵蔬菜的SⅠ 、LI、M5、M8、M4 五株乳酸菌 ,以不同组合发酵蔬菜 ,确定出最佳的发酵菌剂为 2株乳酸杆菌LⅠ 、M8和 2株乳酸球菌M5、SI 按 1∶1∶1∶1组合。在实验条件下 ,接种该发酵菌剂M5M8SILI( 1∶1∶1∶1 )的蔬菜 ,发酵速度快 ,生产出的酸白菜口感适合 (总酸为 0 83%) ,菜色正常 ,特别是在发酵期间未检测出亚硝酸盐 ,菜中也无亚硝酸盐残留。     

The Generation of Nitric Oxide from Aldehyde Dehydrogenase-2: The Role of Dietary Nitrates and Their Implication in Cardiovascular Disease Management

Reduced bioavailability of the nitric oxide (NO) signaling molecule has been associated with the onset of cardiovascular disease. One of the better-known and effective therapies for cardiovascular disorders is the use of organic nitrates, such as glyceryl trinitrate (GTN), which increases the concentration of NO. Unfortunately, chronic use of this therapy can induce a phenomenon known as “nitrate tolerance”, which is defined as the loss of hemodynamic effects and a reduction in therapeutic effects. As such, a higher dosage of GTN is required in order to achieve the same vasodilatory and antiplatelet effects. Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is a cardioprotective enzyme that catalyzes the bio-activation of GTN to NO. Nitrate tolerance is accompanied by an increase in oxidative stress, endothelial dysfunction, and sympathetic activation, as well as a loss of the catalytic activity of ALDH2 itself. On the basis of current knowledge, nitrate intake in the diet would guarantee a concentration of NO such as to avoid (or at least reduce) treatment with GTN and the consequent onset of nitrate tolerance in the course of cardiovascular diseases, so as not to make necessary the increase in GTN concentrations and the possible inhibition/alteration of ALDH2, which aggravates the problem of a positive feedback mechanism. Therefore, the purpose of this review is to summarize data relating to the introduction into the diet of some natural products that could assist pharmacological therapy in order to provide the NO necessary to reduce the intake of GTN and the phenomenon of nitrate tolerance and to ensure the correct catalytic activity of ALDH2.     

The adsorption of methyl nitrite on the Au(111) surface

The interaction of the methyl nitrite molecule (CH₃ONO) with the gold(111) surface has been studied by means of density functional calculations. The perfect Au(111) surface has been represented by a rather large cluster model, Au₂₂, that was in turn used to extract information about the preferred adsorption geometry of the CH₃ONO species. Vibrational frequencies and adsorption energy are also reported. The calculated adsorption energies are 31.2 kJ/mol with respect to gas phase cis-conformer and 35.1 kJ/mol with respect to trans-methyl nitrite, very close to the experimental adsorption energy of 33.5 kJ/mol. From the analysis of vibrational frequencies of gas phase and adsorbed species it is concluded that only the cis-conformer is present at the Au(111) surface.     

Alaska Pollock (Theragra chalcogramma) Mince and Surimi as Partial Meat Substitutes in Frankfurters: N-Nitrosodimethylamine Formation

Studies were conducted to determine the feasibility of using 3 forms of Alaska pollock (AP) as a partial substitute for meat in a nitrite-cured product. The effect of several pre- and post-processing storage conditions on N-nitrosodimethylamine (NDMA) were studied in frankfurters substituted with 15 and 50% unwashed and washed mince and surimi. In franks made with unwashed mince, frozen stored prior to processing, NDMA increased during frozen storage; little change was observed in franks containing washed mince and surimi. Refrigerated storage of franks generally showed a decrease in NDMA with all 3 forms of fish. Overall, the use of washed mince and surimi at the 15% substitution level gave mean values less than 2 ppb NDMA, even after boiling. The results indicate that 50% unwashed AP mince should not be used as a partial substitute for meat in frankfurters.     

糖基化血红蛋白着色剂在肉制品中的应用

将不同发色剂添加到熟肉饼中,通过测定不同组别的色差值来判断发色剂的发色效果。结果表明,添加血红蛋白着色剂的两组(经过腌制和不经腌制)发色效果都比较好,与添加亚硝酸钠的组分比较,颜色差别不显著(P>0.05),因此从发色效果上看血红蛋白着色剂能完全替代亚硝酸钠在肉制品中起发色作用。     

肉制品中亚硝酸盐替代品的研究进展

目前肉制品生产中,普遍使用亚硝酸盐作为发色剂,它赋予肉制品诱人的色泽,并对肉毒梭状芽孢杆菌有抑制作用。但亚硝酸盐具有毒性,可与胺类物质生成强致癌物质亚硝胺,因而人们一直力图寻求合适的物质取而代之。