Microbiological contamination and evaluation of sanitary conditions of hot dog street vendors in Southern Brazil

The consumption of street-food is a common habit worldwide and during the last years has grown substantially in Brazil. However, hygienic conditions are frequently not ideal, and may result in microbial contamination and foodborne diseases. In this study, the microbiological quality and sanitary conditions of hot dog vendors of Southern Brazil were evaluated. Hot dog samples (n = 20) were analysed for total and fecal coliforms and coagulase-positive staphylococci. The sanitary conditions of vendors were analysed using a questionnaire composed by five blocks of questions focusing on food handlers, installations and equipment, raw materials and ingredients, storage and preparation of food, and documents. Results demonstrated that 75% of the hot dogs were contaminated with total coliforms, 30% of them presented fecal coliforms while 25% coagulase-positive staphylococci levels above the maximum limit permitted by Brazilian regulations. Questionnaire results demonstrated that the majority of vendors defrosted sausages at environmental temperature or inadequate cooling. Not one of vendors had a thermometer and several of them used non-potable water. Other frequent unconformities were the lack of cross contamination preventive measures, lack of time and temperature controls and the use of ingredients with unknown origins. Therefore, the hygienic and sanitary conditions of hot dog vendors in Southern Brazil were not adequate, indicating a health risk to consumers.     

Assessment of estimated daily intake of nitrite by average consumption of processed foods in Korea

This study has been performed to estimate the average daily intake of nitrite used in Korea as a color fixative. The crude estimation of daily intake was calculated based on maximum permitted levels (MPL) and national food disappearance data in 1998. In order to refine estimated daily intake (EDI), daily food consumption nationwide National Health and Nutrition Survey in 1998 and the concentration of nitrite in their permitted foods were applied. The crude EDI of nitrite was 17.85 μg/kg bw/day, representing 25.5% of acceptable daily intake (ADI) assigned by JECFA. The refined average EDI for nitrite was 0.87 μg/kg bw/day, representing 1.25% of ADI. For average consumers of age–sex groups ranged from 0.2 to 4.8 μg/kg bw/day, representing 0.3%–6.9% of the ADI.     

Highly sensitive and selective spectrofluorimetric determination of nitrite in food products with a novel fluorogenic probe

A simple, sensitive, selective and convenient spectrofluorimetric method for detection of nitrite has been successfully developed. This method is based on the highly efficient and specific reaction of nitric oxide with a dihydropyridine derivative to form a highly fluorescent pyridine derivative, in aqueous solution. Under optimum conditions, excellent detection linear range was achieved from 0.2 to 4.5 μmol L⁻¹ with a detection limit of 0.02 μmol L⁻¹ (S/N = 3), lower than or comparable to most of other spectrofluorimetric methods. The relative standard deviation for ten determinations of 2.0 μmol L⁻¹ nitrite was 1.0%. The proposed method has been applied to determine nitrite levels in food products with recoveries of 93.3%–103.5%.     

Natural gas hydrate dissociation by hot brine injection

Hot brine injection is one of the most effective dissociation methods of natural gas hydrate, and the movement of thermal front is a key parameter to evaluate the production performance by hot brine injection. Based on the principle of energy conservation, a mathematical model for thermal front movement of gas hydrate dissociation by hot brine injection is developed, which is derived through Laplace transform. In addition, an experimental study on the movement of thermal front is conducted with a self-designed 1D natural gas hydrate dissociation apparatus. The thermal front movement of the experiment is compared with that calculated from the mathematical model established in this paper as well as other two models proposed by Selim and Sloan (1990 Selim, M. S., and Sloan, E. D. (1990). Hydrate dissociation in sediment. SPE 16859. [Google Scholar]) and Tang et al. (2006 Tang, L., Li, G., Feng, Z., et al. (2006). Mathematical simulation of gas hydrate dissociation by heating injection. Nat. Gas Industry 26:105–107. [Google Scholar]), respectively. It turns out that what fits better with the experimental data is the energy conservation model, which includes the effect of heat used to warm the dissociated reservoir, heat absorption by hydrate dissociation and heat loss to the cap and base sediments. Therefore, this energy conservation model is an effective method to analyze the thermal front of gas hydrate dissociation by hot brine injection.     

空心杆热洗工艺技术应用

针对采用封上采下工艺油井无法进行热洗、加药等日常生产管理的问题,开发应用了空心杆热洗工艺,对于这类油井的清蜡提供了一种有效的技术手段。该工艺通过开发研究井下热洗阀组和地面热洗装置及配套工具,热洗时通过建立空心杆和油管的循环通道,避免了热洗介质污染油层现象的发生,同时解决了油套不通油井日常生产时的清蜡等问题,克服了传统油套反循环热洗清蜡工艺的弊端,提高了热洗效率,提高机械采油井的生产时率,清蜡彻底,并且节约大量热洗介质。目前在江苏油田试采一厂成功实施了7井次的热洗工作,取得了一定的效果。     

Influences of vanillin and licorice root extract supplementations on the decimal reduction times of Escherichia coli O157:H7 in mildly heated young coconut liquid endosperm

This study determined the influences of supplementing different combinations of vanillin (0–500 ppm) and licorice root extract (LRE, 0–420 ppm) on the mild heat (55 °C) decimal reduction times (D₅₅-values) of a cocktail of Escherichia coli O157:H7 in young coconut liquid endosperm. The maximum level of supplementation per additive tested was previously established not to result in the lowering of general consumer acceptability of the liquid endosperm. The D₅₅-values ranged from 15.08 to 31.40 min. The influences of both additives on the D₅₅-value fitted significantly into a 2-factor, interaction model with only the joint effect of the additives having significant effect on D₅₅. The combined efficacies of the additives were most significant at concentrations above 250 ppm vanillin and 210 ppm LRE. The results obtained may be used in the establishment of mild heat pasteurization processes for supplemented young coconut liquid endosperm, for better control of quality and safety.     

Surveillance of nitrite level in cubilose: Evaluation of removal method and proposed origin of contamination

The discovery of nitrite contamination aroused public concern on the safety of cubilose consumption. Here, forty-eight batches of cubilose were randomly purchased from Hong Kong market. The median nitrite content of different types of cubilose was as follows: Red cubilose (600 ppm) > Yellow cubilose (510 ppm) ;> White cubilose (100 ppm). Under a developed standardized processing method, up to 98% of nitrite was removed from cubilose; nitrite was not detected in the stewed cubilose. To search for the source of nitrite, droppings from swiftlets and water samples were collected from production sites of cubilose in Malaysia and Indonesia, and which contained a high amount of nitrate. On the other hand, the protein extract of cubilose was subjected to proteomics analysis. A microbial nitrate reductase was identified by mass spectroscopy, which converted nitrate to nitrite in cubilose. A specific inhibitor of nitrate reductase successfully abolished the nitrate reduction activity found in cubilose, which subsequently reduced the nitrite in cubilose. This phenomenon was successfully proven by the field study. Thus, the nitrite on cubilose could be a result of the contaminating nitrate reductase.     

Synergistic combination of heat and ultrasonic waves under pressure for Cronobacter sakazakii inactivation in apple juice

The combined effect of the simultaneous application of heat and ultrasonic waves under pressure (manothermosonication, MTS) on the survival of a strain of Cronobacter sakazakii was studied in apple juice. Below 45 °C, the inactivation by ultrasound under pressure was independent of temperature. Above 64 °C, the lethal effect of ultrasound under pressure was negligible when compared to the lethality of the heat treatment at the same temperature. Between 45 °C and 64 °C, the lethality of the combined process (MTS) was higher than expected if heat and ultrasound under pressure processes acted simultaneously but independently, that is, a synergistic effect was observed. The maximum synergistic effect (38.2%) was found at 54 °C. Recovery on selective media - with sodium chloride or bile salts - revealed that a certain proportion of the survivors after MTS treatments were sublethally injured. It was also observed that survivors after MTS treatments progressively died during refrigerated storage (up to 96 h at 4 °C) in the apple juice. The practical implication of these findings is discussed.     

Combinations of selected physical and chemical hurdles to inactivate Escherichia coli O157:H7 in apple and orange juices

This study evaluated the individual and combined efficacies of physical processing techniques such as heating, Dynashock multi-frequency ultrasound waves, ultraviolet-C (UV-C), and additives such as sodium benzoate, potassium sorbate, α- and β-Pinene for pasteurization of orange and apple juices against acid-adapted Escherichia coli O157:H7. In heated apple juice, log-linear inactivation of the test organism resulted in D values which were used to calculate for the recommended 5-log reduction process schedules (t_5D) at 45, 50, 52, 55, and 60 °C equal to 481.5, 103.6, 45.0, 22.4, and 10.54 min, respectively. E. coli O157:H7 exhibited biphasic inactivation composed of a slow inactivation lag, followed by log-linear inactivation in ultrasound-treated juice. t_5D schedules were similarly calculated at 54.7 and 77.5 min for orange and apple juice, respectively. Lethal rate analyses in the ultrasound-treated apple juice revealed that 85% of the reduction in E. coli population was due to the heat liberated by cavitation. Combined ultrasound and UV-C treatment resulted in greater inactivation rates in both juices, with greater efficacy in apple juice. Supplementation of all tested additives, whether singly or in combination, similarly resulted in significantly shorter t_5D schedules in both juices.     

成品油管道与热原油管道同沟敷设技术研究

同沟敷设管道中成品油管道和原油管道间的传热对原油管道的运行有一定的影响。采用非结构化有限容积法,对成品油和原油管道内复杂的流动和传热问题进行了数值模拟。为了确定同沟敷设成品油管道对原油管道的影响,对相同条件下单独敷设的原油管道进行了水力和热力计算,并与同沟敷设管道的计算结果进行了对比。结果表明,两条管道的间距取1.2m时,原油管道沿线温度受成品油管道的影响较小。     

热风供暖技术在烘窑设计中的应用

为节约蒸汽,改进了传统烘窑的工艺设计,在烘窑的内增设一套强制通风系统,其喷口出风温度８０℃左右,风速８ｍ／ｓ,喷口直径４０ｍｍ,喷口倾角４５℃,并在烘窑地面下设一组加热盘管,经过改造后,烘窑内物产的烘干时间同原来的４天减少至１．８天,获得了较好的经济效益。     

计算机技术在高聚物研究中的应用

介绍了计算机信息系统计算机辅助系统、计算机控制系统在高聚物研究中的应用概况,详述了计算机仿真技术在此领域中的应用及其研究进展。     

降低丙烯酸精制单元废水中丙烯酸含量

中国石油兰州石化公司8万t／a丙烯酸生产装置采用丙烯两步氧化法,通过共沸精馏制备聚合级丙烯酸。在进料量为19．0t／h,轻组分分馏塔塔顶压力为（15．0±0．5）kPa,塔釜温度为78．6—79．6℃,回流比为7．8～8．0的条件下,可以将废水中丙烯酸质量分数从目前的0．5％-1．0％降低到0．35％以下。回收丙烯酸的经济效益为63．79万元／a,降低蒸汽用量为25200t／a。     

浅谈沼气制氢技术在PTA工厂中的应用

从PTA装置对H2的需求出发,结合PTA工厂污水处理装置产生副产沼气,简要介绍沼气制氢技术的工艺原理和过程。通过分析,阐述在PTA工厂应用和推广副产沼气制氢技术,既节能减排,又具有良好的经济效益和社会效益,前景非常可观。     

降低催化裂化汽油烯烃含量技术进展

介绍了降低催化裂化汽油烯烃含量的途径,包括选择合适的催化裂化工艺、应用降烯烃催化剂和助剂、选择中质中间基FCC原料、对原料进行预处理以及对催化裂化汽油进行后处理等。简述了各种催化裂化工艺和降烯烃催化剂及助剂在部分FCC装置的应用效果。指出要实现油品的清洁化,应开发FCC汽油醚化工艺,建造汽油加氢、重整、异构化和烷基化装置。     

未来石化工业的技术发展热点:Ⅱ.合成气生产燃料和化学品以及轻质烷烃活化技术

2　合成气生产燃料和化学品及轻质烷烃活化技术2 .1　生产燃料和化学品的技术 ①利用合成气生产燃料和化学品的技术将在炼油厂渣油和焦炭 (甚至于煤炭 )的深度转化及偏远地区天然气高效利用中得到推广应用。合成气生产燃料和化学品技术的流程如图 2所示。图 2　合成气生产燃料和化学品流程示意2 .1 .1　炼油厂气化一体化联合循环技术气化一体化联合循环 (IGCC)技术已成为现代化炼油厂渣油改质、减少污染排放的优选工艺之一[1 4 ] 。IGCC技术采用高硫渣油 (或焦炭 )等炼厂劣质进料 ,通过基于部分氧化的气化技术产生合成气 ,不仅可使合成…     

设计单位应用统计技术的探讨

根据ISO9000标准所规定的统计方法应用范围,探讨了设计单位如何在实际工作中应用统计技术,并分析了统计技术应用的控制步骤和实施统计技术应用的难点。     

煤矿采矿工程中的采矿工艺与技术简述

随着采矿工艺与技术的发展,煤矿采矿问题得到有效解决,也实现煤矿采矿效益的较大提升。煤矿企业应充分掌握各类采矿工艺,结合煤矿结构特点,做好采矿工艺与技术的选择,更好地保障煤矿效益及安全。本文首先就煤矿采矿工艺予以分析,提出了煤矿采矿工艺技术应用需注意的问题,并对其发展趋势展开研究,旨在提高采矿工艺技术应用水平。     

多组合找漏找窜测井技术在河南油田的应用

针对河南油田开发后期出现的套管漏失、管外窜槽等影响水井有效注水或油井正常生产的井下技术状况复杂问题,在分析单一油水井找漏找窜技术缺陷的基础上,提出了采用提取地层和井况信息多、测量范围大、精度高、工艺环保的井温、流量、示踪剂和氧活化水流等多组合找漏找窜测井技术。实际应用表明,该测井技术可准确评价判断油水井套管漏失或管外窜槽情况,为不正常注水井、采油井有效治理提供了科学依据,并在河南油田稀油油藏中被广泛应用,取得了较好的效果。