Inactivation of Staphylococcus saprophyticus in chicken meat and purge using thermal processing,high pressure processing,gamma radiation,and ultraviolet light (254 nm)

Staphylococcus saprophyticus is a common contaminant in meat and poultry, and causes urinary tract infections after colonization of the gastrointestinal tract, followed by accidental transfer of contaminated feces to the urethra. There is limited information regarding the inactivation kinetics of S. saprophyticus in meat and poultry. When S. saprophyticus was suspended in ground chicken meat (GCM) the thermal processing D₁₀ was 6.26, 0.60 and 0.09 min at 55, 60 and 65 °C, respectively. When S. saprophyticus was inoculated into GCM and subjected to high pressure processing (5 °C, 0–25 min) at 200, 300 or 400 MPa the HPP D₁₀ was 15.5, 9.43, and 3.54 min, respectively. When the S. saprophyticus cocktail was inoculated into GCM and irradiated (5 and −20 °C) the gamma radiation D₁₀ were 0.64 and 0.77 kGy, respectively. When S. saprophyticus was inoculated into chicken purge which was then placed on food contact surfaces including stainless steel, and high density polyethylene and polypropylene and treated with UV-C (0–60 mJ/cm²) the UV-C D₁₀ ranged from 14.9 to 18.5 mJ/cm². These results indicate the inactivation kinetics for S. saprophyticus are consistent with those for other foodborne pathogens and could be controlled in poultry meat and purge without difficulty.     

Estimation of solar radiation components incident on Helwan site using neural networks

Field testing carried out for solar energy applications is costly, time consuming and depends heavily on prevailing weather conditions. Adequate security and weather protection must be provided at the test site. Measurements may also suffer from delays that can be caused by system failures and bad weather. To overcome these problems the need for accurate model becomes evermore important. To achieve such prediction task, an artificial neural network, ANN, model is regarded as a cost-effective technique superior to traditional statistical methods. In this paper, Levenberg optimization function is adopted to predict insolation data in different spectral bands for Helwan (Egypt) monitoring station. The predicted values were then compared with the actual values and presented in terms of usual statistics. The results hint that, the ANN model predicted infrared, ultraviolet, and global insolation with a good accuracy of approximately 95%, 93% and 96%, respectively. In addition, ANN model was tested to predict the same components for Aswan over an 11 month period. The predicted values of the ANN model compared to the actual values for Aswan produced an accuracy of 95%, 91% and 92%, respectively. Data for Aswan were not included as a part of ANN training set. Hence, these results demonstrate the generalization capability of this approach over unseen data and its ability to produce accurate estimates.     

Ozonation of Several Organic Compounds Having Low Molecular Weight under Ultraviolet Irradiation

Ozonation of several low molecular weight organic compounds under ultraviolet irradiation was studied. Nine compounds were identified as reaction products of the ozonation of phenol which was promoted by the simultaneous use of ozone and ultraviolet irradiation. In the case of several organic compounds having carbon numbers from one to six, the removal of total organic carbon (TOC) by this simultaneous use was higher than by either the ozone oxidation method or the ultraviolet irradiation method for all the compounds.     

多波长光谱法测定红糖中总铁和亚铁的含量

国家标准采用原子吸收光谱法测定食品中铁含量,其前处理需要灰化等步骤,操作繁琐,耗时耗能,测的为总铁的含量。本文建立了一种三波长邻菲罗啉显色法测定红糖总铁和亚铁含量的方法,先将红糖直接溶解成一定浓度的红糖溶液,然后按照邻菲罗啉显色法并基于423、510和700 nm波长处的吸光度测出总铁的含量,并进行了红糖中总铁含量的回收率试验。红糖溶液在不添加还原剂的情况下按照相同方法测出亚铁的含量。该方法能够有效扣除了红糖中多种色素以及基线漂移对结果的影响,结果发现试验的红糖样品,其中总铁的含量为(13.65±0.29)mg/kg,亚铁含量为(13.29±0.18)mg/kg,以二价铁为主,占总铁含量98%以上;红糖中总铁含量的回收率约103%。本方法避免了灰化前处理时的繁琐,测定较简便,结果准确,适用于生产企业使用。     

紫外分光光度法测定水体总氮的影响因素

本文就紫外分光光度法在测定水体总氮中易影响测定工作的几个方面做了阐述,并提出了改进意见     

赖氨酸-葡萄糖美拉德反应产物对铜离子的螯合作用

美拉德反应产物(Maillard reactionp roducts,MRPs)具有抗氧化活性,特别是金属螯合作用。本文制备了一定条件下的赖氨酸-葡萄糖MRPs,采用零交一阶导数分光光度法研究了MRPs对铜离子的螯合作用,分析了螯合铜离子对MRPs抗氧化活性的影响。结果表明,螯合铜离子使MRPs中具有紫外光吸收的小分子物质发生电子重排,不影响大分子黑素类物质的发色团结构;一些铜螯合位点对MRPs的还原能力和自由基清除能力有贡献。     

阻抑催化动力学光度法测定柠檬酸

在稀硝酸介质中,柠檬酸能阻抑铁(Ⅲ)催化过氧化氢氧化酚红的褪色反应,据此建立了阻抑动力学光度法测定柠檬酸的新方法。方法检出限为0.10μg/mL,线性范围为0.70～4.0μg/mL。直接用于汽水中柠檬酸的测定,回收率为99%～102%,获得满意结果。     

三波长紫外分光光度法测定红车轴草异黄酮含量的研究

红车轴草乙醇提取液，颜色较深，背景吸收较大，以一般常用的单波长紫外分光光度法测定红车轴草异黄酮含量时，色素和醇溶性蛋白等杂质干扰严重。本文建立的三波长紫外分光光度法，能有效扣除色素和醇溶性蛋白等杂质的干扰，精密度实验的相对标准偏差为0．85％，平均加样回收率为103．95％，加样回收率的相对标准偏差为1．82％。本方法具有简便、快速、准确等特点。     

火焰原子吸收测定固体废物浸出液中锌、镍和铜

采用硫酸硝酸浸提、火焰原子吸收分光光度法测定催化剂固体废弃物中的锌、镍和铜3种元素,加标回收率为93．2—108．5％,相对标准偏差为0．4—1．7％。结果表明,该方法具有检出限低,重现性好、分析效率高、操作简便等优点。     

二硫代安替比林甲烷光度法检测化妆品中砷的研究

研究了砷与二硫代安替比林甲烷的显色反应 ,在 2 mol/L的硫酸介质中 ,砷与试剂发生灵敏的显色反应 ,配合物最大吸收在 32 7nm处 ,0 μg/2 5m L～ 30 μg/2 5m L符合比耳定律 ,摩尔吸光系数为 2 .72× 1 0 4 ,该方法简便、快速、选择性好 ,可用于化妆品中砷的直接测定。