Review of the sensitivity of different foodborne pathogens to fermentation

The characteristics of lactic acid bacterial fermentation and the principal antimicrobial factors produced by lactic acid bacteria (LAB) are reviewed and assessed. The principal anti-microbial factor identified is the ability of all LAB to produce organic acids and decrease the pH of foods in which they grow. Other factors such as the production of bacteriocins, hydrogen peroxide and ethanol may all play a contributory role in assuring the safety of fermented foods but their contribution is secondary. The efect of fermentation on non-bacterial pathogens is discussed. A tabulation is made of results from a number of published studies of the effects of fermentation on the fate of different bacterial pathogens in a vareity of food materials.     

Measures for controlling safety of crushed ice and tube ice in developing country

Contamination of pathogens in crushed and tube ice is a public health concern in many developing countries, calling for the development of practical preventive measures to reduce microbial and chemical contamination. By applying principles of hazard analysis and critical control points (HACCP), data on production and distribution processes in 11 ice-making plants in different provinces of Thailand were obtained. Results showed that producers of both ice forms lacked knowledge on water treatment and disinfection that could cause microbial contamination. Other sources of microbial contamination were from condensate in tube ice production and from dirty sacks used in ice transportation. A chemical hazard also was found in crushed ice due to chromium contamination in an anti-rusting agent.     

Abstracts of selected Articles

The youth isthe future of our motherland, They are expected to realize China＇s dream for the country＇s prosperity, the national powerfulness and people＇s happiness. China National Committee of World Petroleum Council has always attached great importance to development of young experts. It hosted the First Session of the Youth Forum of World Petroleum Council in 2004 to promote mutual exchange among young people of the member nations.     

英文摘要

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The incidence of significant foodborne pathogens in domestic refrigerators

The interior surfaces of household refrigerators are at risk of becoming contaminated with foodborne pathogens, increasing the risks of cross-contamination to other food items, including higher risk ready-to-eat foods. This study determined the incidence of a number of significant foodborne pathogens, and the general hygienic status (as estimated by total viable counts (TVCs), and total coliform counts (TCCs)) on the interior surfaces of domestic refrigerators (n = 342). Campylobacter spp., Salmonella spp. and Escherichia coli O157:H7 were not recovered from any refrigerators, but Staphylococcus aureus was recovered from 6.4%, Listeria monocytogenes and E. coli from 1.2% and Yersinia enterocolitica from 0.6% of examined refrigerators. As the recovered species can survive and grow under refrigeration or conditions of mild temperature abuse, such pathogens may transfer to (and develop to clinically significant numbers in) food in domestic fridges. Such risks are of particular concern in relation to “ready-to-eat” foods, which will not receive further bactericidal treatments (cooking) before consumption. The study estimated TVCs ranging from 2.91 log₁₀ cfu/cm² to 8.78 log₁₀ cfu/cm² and TTCs ranging from 0.045 log₁₀ cfu/cm² to 5.96 log₁₀ cfu/cm² indicating very poor standards of consumer refrigerator management and hygiene, and posing risks to consumer health. The study findings highlight the importance of adequate temperature control and thorough, regular cleaning of domestic refrigerators to ensure food safety, and of effective cooking as the last link in the domestic food service chain.     

干冰清洗技术在注汽锅炉的应用

注汽锅炉在长时间运行后,其对流段翅片管表面积累了大量的灰垢,大大降低了对流段的换热能力,造成了排烟温度升高、热效率降低等问题.与常规的水洗、风吹扫等除垢方法相比,运用压缩空气携带干冰颗粒对结垢炉管的清洗技术,可达到清垢彻底、简便、经济、安全的目的.辽河油田公司特种油开发公司在注汽锅炉上采用该方法,对对流段翅片管进行清洗后.排烟温度由315.6℃下降至241℃,锅炉热效率提高3.6%,节油率提高3.8%,具有重要的节能意义.     

微波辐射技术在有机合成中的应用

探讨了微波辐射在有机反应中的作用原理,综述了近年来微波辐射技术在有机合成中的应用,并展望了微波促进有机化学的发展前景。     

辽河滩海抗冰管架设计中的降耗研究

结合月海油田北部海南3井区天然气外输工程设计中的具体工程实例，论述了降低滩海管线总工程造价的方法。研究认为：通过管架结构型式的优化设计、粗管线拖带细管线以增大管架间距、适当加大管线管径以增大管架间距、利用桁架增大细管线跨距，可有效降低滩海管线总工程造价。     

渤海新型抗冰导管架平台研究

根据渤海海洋平台长期现场监测结果,对渤海海域冰与导管架平台相互作用问题进行了系统研究,指出冰激结构振动是目前渤海冰区导管架平台的主要危害。应用冰激导管架平台冰激振动及动冰力研究成果,对新型抗冰振平台设计方案进行了分析。对适用于导管架平台的冰激振动控制装置进行了理论分析与实验研究。在新建JZ20-2NW平台的设计建造中应用了上述研究成果。新建平台现场监测结果分析表明,新型平台比以往平台具有更好的抗冰振性能。     

锥体上冰力的试验研究

通过冰力模型试验,研究了锥体冰力的特征。试验得到的正锥体冰力大都小于美国API荐用Ralston公式计算的冰力,Ralston公式未反映冰速对冰力的影响;多锥体前冰的非同时破坏现象以及锥间距对冰力计算具有不同程度的影响;冰在正、倒锥体交界线上的破坏为挤压破坏,其冰力远小于作用在同直径桩柱上的冰力。     

动冰力模型试验模型律研究

冰激直立桩结构振动模型试验研究结果表明,冰条件和结构条件的组合形成了对结构响应形式的综合控制,冰激直立结构稳态振动控制机理为冰与结构的相互作用。基于动冰力模型试验数据,提出了由弹性控制因子、率控制因子以及几何尺寸控制因子组成的能够反映冰与结构相互作用水平的相互作用系数,并建立了以相互作用系数为相似准数的相似体系。所建立的相似体系可以确定引发结构稳态振动的结构条件与冰条件组合,对研究动冰力模型试验具有指导意义。