An original transesterification route for fatty acid ester production from vegetable oils in a solvent-free system

Wax ester production from a long-chain alcohol and methyl ester has been investigated with an immobilized thermostable lipase (lipozyme IM from Novo Nordisk). The transesterification reaction rate was monitored in solvent-free medium that was exclusively composed of the reactants and the enzyme. The transesterification is performed by simply mixing the two substrates in various stoichiometric amounts at a temperature range from 55 to 65°C under constant stirring in the presence of low concentrations of enzyme preparation (0.12 to 2%, w/w). Long-chain reactants produce waxes of high molecular mass that induce low solubility and high viscosity. On average, high transesterification yields are obtained (around 95%). Thermodynamic parameters involving substrate concentration and temperature have also been investigated. The balance between optimal working temperature and the molar ratio of substrates in such a complex medium appears to be 60°C, with a molar ratio methyl oleate/stearyl alcohol of 1:0.5. Substrate inhibition due to stearyl alcohol has been observed. A study of kinetic parameters has confirmed these results.     

Simulation of decontamination and transmission of Escherichia coli O157:H7, Salmonella Enteritidis,and Listeria monocytogenes during handling of raw vegetables in domestic kitchens

Epidemiological data indicates that a large number of foodborne illnesses are attributed to cross-contamination during food preparation in the domestic kitchen. The objectives of this study were to evaluate the efficiency of household washing practices in removing Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Enteritidis on artificially contaminated lettuce and to determine the transfer rate of these three foodborne pathogens from contaminated lettuce to wash water, tomato, cabbage, and cutting boards during washing and cutting processes. Washing under the running tap water with scrubbing for 60 s was the most effective method in reducing pathogen populations by 1.86–2.60 log₁₀ CFU/g. Also, final rinsing and scrubbing practices were found to enhance the efficiency of washing treatment. In this study, the transfer rates of S. Enteritidis, E. coli O157:H7, and L. monocytogenes from cutting board to cabbage and tomato via cutting process (17.5–31.7%) were higher (P < 0.05) than from wash water to cabbage and tomato (0.8–23.0%) during washing treatment. Overall, our findings suggest that wash water and cutting board can be potential vehicles in the dissemination of foodborne pathogens. Therefore, there is a need to promote consumer awareness for proper handling practices in the kitchen to minimise the risk of foodborne infection.     

油田轻烃加氢生产低芳烃含量溶剂的两种工艺比较

以硫质量分数分别为106μg?g和25μg?g的两种油田轻烃作为原料,比较两种加氢工艺的适用性。工艺Ⅰ采用CoMo?Al2O3加氢脱硫-中温ZnO吸附-Ni?Al2O3加氢脱芳烃的组合工艺;工艺Ⅱ采用Ni?ZnO吸附脱硫串联Ni?Al2O3加氢脱芳烃的组合工艺。结果表明:对于工艺Ⅰ,两种原料在反应初期产品溴指数和芳烃含量均较低,但反应400h和550h后,产物芳烃质量分数大于0.1%;对于工艺Ⅱ,原料硫质量分数为25μg?g时,在1 000h内产品溴指数稳定在16mgBr?(100g)以下,芳烃质量分数稳定在0.09%以下。因此,工艺Ⅱ适合用于硫质量分数低于25μg?g原料的深度加氢生产超低芳烃含量溶剂。     

Suitable additives for vegetable oil‐based automotive shock absorber fluids: an overview

Formulation of a cost‐effective, high‐performance and eco‐friendly lubricant, largely depends on the base oil quality, then the selection of suitable additives and their proportions. Vegetable oils, identified to be eco‐friendly, renewable, future‐available and cost‐effective treasures for lubricant formulation, apart from processing, will rely much on suitable additives to meet the performance requirements for automotive shock absorber (ASA) fluids. Additives that will guarantee performance, longevity and eco‐friendliness of formulated vegetable‐based functional fluids have to be uncommonly effective, resistant to depletion, non‐toxic and highly biodegradable. Their selection in these regards will require skills and experience, which will harness the various arms of synergism as effective tools to succour the known weaknesses of the base oil. This is a review on additives that could be used in formulation of vegetable oil‐based (ASA) fluids. The outcome shows that there are customary and novel additives that are suitable for formulating vegetable oil‐based ASA fluids. Copyright © 2016 John Wiley & Sons, Ltd.     

铬在铁合金厂周边土壤-蔬菜系统中的迁移转化及健康风险

分析湖南省某铁合金厂附近重金属铬在土壤中的分布及迁移特征,在土壤-植物系统中的迁移转化规律,以及铬污染蔬菜对人体的健康风险。结果表明：铁合金厂外排污口、污灌区和对照区土壤的铬含量平均值分别为2239.5,995.33和104.9mg/kg。总铬在排污口附近土壤中主要富集在地表下200-400mm;在污灌区,主要富集于地表下0-200mm;而在对照区,铬浓度从上至下逐渐降低且各层之间富集浓度相差不大。结果也表明芹菜、莴苣和白菜均能够把土壤中吸收的致毒性较强的六价铬转化成低毒的三价铬,且蔬菜中的铬含量平均值为11.95mg/kg。铬在土壤–蔬菜中的生物富集因子大小依次为：白菜〉莴苣〉芹菜。居民每天摄入的铬含量严重超过食物中最大铬允许摄入量,表明铬污染对当地居民存在一定的健康风险。     

Preservation of acidified cucumbers with a combination of fumaric acid and cinnamaldehyde that target lactic acid bacteria and yeasts

The naturally occurring compound, fumaric acid, was evaluated as a potential preservative for the long-term storage of cucumbers. Fumaric acid inhibited growth of lactic acid bacteria (LAB) in an acidified cucumber juice medium model system resembling conditions that could allow preservation of cucumbers in the presence of sodium benzoate. Forty millimolars of fumaric acid were required to inhibit growth of an extremely aciduric Lactobacillus plantarum LA0445 strain at pH 3.8. Half of this concentration was required to achieve inhibition of L. plantarum LA0445 at pH 3.5. As expected growth of the spoilage yeasts Zygosaccharomyces globiformis and Z. bailii was not inhibited by fumaric acid at near saturation concentrations in the same cucumber juice medium. To usefully apply fumaric acid as a preservative in acidified foods it will be necessary to combine it with a food grade yeast inhibitor. The antimicrobial agent, cinnamaldehyde (3.8 mM) prevented growth of Z. globiformis as well as the yeasts that were present on fresh cucumbers. Acidified cucumbers were successfully preserved, as indicated by lack of yeasts or LAB growth and microbial lactic acid or ethanol production by a combination of fumaric acid and cinnamaldehyde during storage at 30 °C for 2 mo. This combination of 2 naturally occurring preservative compounds may serve as an alternative approach to the use of sodium benzoate, potassium sorbate, or sodium metabisulfite for preservation of acidified vegetables without a thermal process. PRACTICAL APPLICATION: This study evaluates the potential application of alternative preservatives for the long-term storage of cucumbers in a reduced NaCl cover brine solution and without a thermal process.     

氯丙醇产生的原因及清除办法

本文对氯丙醇的特性、毒性、形成机理、抽检情况、限量指标、清除研究进展、清除理论、清除试验、清除工艺进行了论述，这对于酸水解植物蛋白调味液、水解蛋白、酱油等类产品有效地控制3－氯－1，2丙二醇（3－MCPD）的含量并使其符合卫生质量标准将具有一定的参考价值。     

常见植物染料黄色系的色素提取及染色分析

分别对栀子、姜黄、槐米和黄檗这几种植物的性状、药理价值作了介绍，并对这几种常用的黄色染料的色素提取方式以及在棉布和真丝面料上的染色效果进行了实验、论述和分析。     

部分变性植物油作苎麻油剂应用研究

将植物油磺化变性取代部分乳化剂,则解决自乳化油剂的成本问题.研究了植物油种类、硫酸变性工艺、辅助乳化剂等因素对油剂性能的影响,结果表明:渍(浓硫酸)为2%(对植物油体积),2%体积的浓硫酸以约0.5滴/秒的速度滴加到植物油中进行部分变性、再加入辅助复合乳化剂可得到自乳化油剂.该油剂克服了传统油剂所存在的问题,生产成本低,稳定性好,可在较低温度下实现给油,具有良好的推广应用前景.     

沥青混凝土面板防渗层木质素纤维掺量试验研究

张河湾抽水蓄能电站上水库通过添加木质素纤维的方法来改善其高温下库坡沥青混凝土面板防渗层的稳定性．分析在不同沥青用量下，木质素纤维掺量与沥青混凝土的斜坡流淌值的关系，对不同木质素纤维掺量下的拉伸应变值和弯曲应变值进行比较，得出木质素纤维的最佳掺量．