牛乳中β-内酰胺酶的检测方法研究进展

β-内酰胺酶可以水解生鲜奶中β-内酰胺类抗生素,使检测方法无法正确判断其是否为"无抗奶",掩盖抗生素超标的事实.对牛乳中β-内酰胺酶的结构、残留的现状和危害、检测方法的研究进展进行综述.     

"生鲜牛乳抗生素分解剂"的鉴定与检测

目的鉴定“生鲜牛乳抗生素分解剂”的主要成分,调查北京零售牛奶中是否含有“生鲜牛乳抗生素分解剂”。方法通过青霉素分解实验和蛋白电泳实验分析生鲜牛乳抗生素分解剂的有效成分,建立了牛奶中分解剂的检测方法,并运用该方法对从零售市场上随机采集的5个厂家生产的38份牛奶样品进行了分析。结果“生鲜牛乳抗生素分解剂”的主要成分是β-内酰胺酶,运用β-内酰胺酶特异性抑制剂舒巴坦建立了该酶的检测方法,该方法在牛奶中的检出限为4 U/mlβ-内酰胺酶。38份市售牛奶样品中63.2%(24/38)检出β-内酰胺酶,21.1%(8/38)样品中残留的β-内酰胺酶可使得25μg/ml舒巴坦和0.5μg/ml青霉素G所产生的抑菌圈与添加0.5μg/ml青霉素G所产生的抑菌圈直径差异大于或等于6 mm;10.5%(4/38)样品中残留的β-内酰胺酶可使得25μg/ml舒巴坦和0.5μg/ml青霉素G所产生的抑菌圈与添加0.5μg/ml青霉素G所产生的抑菌圈直径差异大于或等于10mm。结论“生鲜牛乳抗生素分解剂”的主要成分β-内酰胺酶为我国不允许使用的食品添加剂,该酶的使用掩盖了牛奶中实际含有的抗生素,为保障人民身体健康,应加强对牛奶中β-内酰胺酶的监管。     

生牛乳中β-内酰胺酶检测杯碟法的优化

内酰胺酶能将牛乳中抗生素残留量降到限量标准,基于该原理,出现人为向乳及乳制品中加入β-内酰胺酶,营造“无抗奶”的假象,增加乳品行业的安全风险。而β-内酰胺酶杯碟法被认为是较为可靠的方法,但牛体本身会产生β-内酰胺酶及牛体本身感染某些抗性的微生物,这些微生物在体内不断表达分泌β-内酰胺酶类,致使出现假阳性现象。为准确控制生鲜牛乳的质量、提高检测准确性,需对生鲜牛乳中β-内酰胺酶杯碟法进行优化研究。在β-内酰胺酶杯碟法的基础上增加检测牛乳内源性β-内酰胺酶方法,排除内源性β-内酰胺酶的干扰,旨在为加强我国乳制品中的抗生素监测、解决乳品工业发展中面临的难题提供参考。     

南通市市售牛乳中β-内酰胺酶检测结果分析

目的 调查南通市市售牛乳中是否含有生鲜牛乳抗生素分解剂—β-内酰胺酶。 方法 采用卫生部颁布的“乳及乳制品中舒巴坦敏感β-内酰胺酶类药物检验方法—杯碟法”检测牛乳样品中的β-内酰胺酶。结果 5家公司被检测102份牛乳,其中有2家共15份被检出β-内酰胺酶。15份β-内酰胺酶阳性的牛乳标本抑菌圈直径差值(B-A)在3.9~17.9mm之间。结论 南通市部分市售牛乳检出β-内酰胺酶,有一定的食用安全隐患,应采取措施加强监管。     

牛乳中β-内酰胺类抗生素残留及检测方法的比较

介绍了牛乳中抗生素残留的原因及危害，描述了β-内酰胺类抗生素在牛乳中的残留特性及残留现状，阐述了不同抗生素残留检测方法的优缺点，为牛乳中抗生素残留的检测提供理论参考。     

牛乳中β-内酰胺类抗生素残留及检测方法的比较

介绍了牛乳中抗生素残留的原因及危害，描述了β-内酰胺类抗生素在牛乳中的残留特性及残留现状，阐述了不同抗生素残留检测方法的优缺点，为牛乳中抗生素残留的检测提供理论参考。     

陕西省生鲜乳中β-内酰胺酶的检测与结果分析

本次检测共有149份生鲜乳样品,其中鲜牛乳96份,鲜羊乳53份。旨在了解陕西省生鲜乳中是否含有β-内酰胺酶及其残留状况。采用食品整治办[2009]29号指定检验方法4《乳及乳制品中舒巴坦敏感β-内酰胺酶类物质检验方法-杯碟法》。结果共检出17份β-内酰胺酶阳性样品,阳性样品检出率为11.4%。17份阳性样品中,鲜牛乳9份,鲜牛乳阳性样品检出率为9.4%;鲜羊乳8份,鲜羊乳阳性样品检出率为15.1%。17个阳性样品的dA与dB差值较大在6.08-13.3mm。本次检测样品阳性检出率较高为11.4%,且阳性样品中所残留的β-内酰胺酶含量较高,可见生鲜乳中抗生素和β-内酰胺酶监管形势依然严峻。     

乳及乳制品中β-内酰胺酶检测方法的研究

基于酶活测定及青霉素分解实验,研究了市售的生鲜牛乳抗生素分解剂中所含β-内酰胺酶活力、其在乳制品中最低检出限及其在液态乳制品中活力残留,结果表明,市售的四种生鲜牛乳抗生素分解剂(A、C、D及E)主要成分为β-内酰胺酶,其酶活力分别为5672590、1174215、1008126、1414437U/mL;经十万倍稀释后,可检出它们在乳中残留的酶活;经百万倍稀释后,只能检出A在乳中残留的酶活。巴氏杀菌和UHT可导致乳中残留的β-内酰胺酶活力损失近50%。73份牛奶样品中,原料乳中β-内酰胺酶检出率较高,占所检样品总数的12·33%;而巴氏杀菌乳和UHT乳样品β-内酰胺酶检出率较低,仅分别占所检样品的2·74%和1·36%。     

分解酶对牛乳中抗生素检测的影响

影响乳制品品质的因素有很多,其中原料的质量安全是首先要关注的。食品添加剂的使用在延长保质期、增加风味的同时,也带来了一定的安全隐患。β-内酰胺酶可分解并掩盖抗生素在生乳中的残留量,在很大程度上对检测工作带来了困难,对生乳中抗生素的残留、检测方法和β-内酰胺酶的研究现状、检测2个方面进行了论述。     

两种牛乳中添加β-内酰胺酶检测方法的研究

对两种牛乳中添加β-内酰胺酶的检测方法进行了对比——杯碟法与碘量法得出各自的优缺点,同时对碘量法进行了优化,对于牛乳中添加β-内酰胺酶的检测,两种方法可以配合使用,碘量法用于快速检测和简单的现场检测,而杯碟法则用于最终的验证。这样可以降低成本,保障收购生鲜乳的质量。     

Changes in smoking prevalence in Ukraine in 2001-5

Objectives

To analyse trends in smoking prevalence in Ukraine from three surveys conducted in 2001–5, and to explore correlates of observed changes, in order to estimate the stage of tobacco epidemic in Ukraine.

Design

Repeated national interview surveys in Ukraine in 2001, 2002 and 2005.

Main outcome measure

Prevalence of current smoking among the population aged ⩾15 years.

Results

The age‐standardised prevalence of current smoking in Ukrainian men was 54.8% in 2001 and 66.8% in 2005. Among Ukrainian women, prevalence increased from 11.5% in 2001 to 20.0% in 2005. ORs for yearly increase in prevalence were estimated as 1.164 (95% CI 1.111 to 1.220) for men and 1.187 (1.124 to 1.253) for women, which implies that, on average, 3–4% of men and 1.5–2% of women living in Ukraine join the smoking population each year.

Conclusions

In Ukraine, smoking prevalence is increasing in most population groups. Among men, the medium deprivation group with secondary education has the highest smoking prevalence. Among women, while the most educated, young and those living in larger cities are the leading group for tobacco use, other groups are also increasing their tobacco use. Tobacco promotion efforts appear to have been significantly more effective in Ukraine than smoking control efforts. The decrease in real cigarette prices in Ukraine in 2001–5 could be the main factor explaining the recent growth in smoking prevalence.Ukraine is a large eastern European country with high smoking prevalence. Tobacco products are widely available at very low prices, and the transnational tobacco industry is extremely successful in promoting its products and lobbying for its interests in the legislative field. Advocacy of tobacco control has only recently achieved some success in the legislative field, with the first tobacco control law being adopted in late 2005. Ukraine ratified the Framework Convention on Tobacco Control in 2006, but there is still much cause for concern regarding the enforcement and effectiveness of the adopted legislative measures. Unfortunately, the government is not yet involved in nationwide surveillance of the tobacco problem, and the available data have mostly been gathered with funding from foreign donors. Several attempts have been made to measure the extent of the tobacco epidemic in the countries of the former Soviet Union (FSU).^{1,2,3,4,5,6,7} Most of these studies have shown rather high smoking prevalence among men (50–70%) and comparatively low prevalence among women (5–20%). Most countries in the FSU have similar smoking rates, while certain trends are shown to be related to the differences in how the transnational tobacco industry succeeds in every national tobacco market.⁶ Unfortunately, few studies have been published showing trends in smoking prevalence in the FSU.⁷ In Ukraine, two studies^3,4 provided point estimates of smoking prevalence.The aim of this study was to analyse trends in smoking prevalence in Ukraine, on the basis of three surveys conducted in 2001–5, and to explore correlates of observed changes in order to estimate the stage of the tobacco epidemic in Ukraine.     

2010年河南省部分食品中重金属污染状况分析

了解河南省部分食品中重金属污染的现状。方法 在河南省18个省辖市采集8大类3 657份食品样品,按照国家标准检测食品中铅、镉和汞的含量,检测结果按照GB 2762—2012《食品安全国家标准食品中污染物限量》进行评价。结果 河南省部分食品中铅含量的平均值为0.34 mg/kg,总体超标率为8.8%(320/3 656),其中粮食、肉类和蔬菜中超标率较高,分别为17.2%(95/552)、14.5%(85/587)和10.7%(57/534);部分食品中镉含量的平均值为0.054 mg/kg,总体超标率为3.9%(143/3 657),其中食用菌和蛋类中超标率较高,分别为9.6%(49/508)和8.1%(42/518);部分食品中汞含量的平均值为0.077 mg/kg,总体超标率为8.3%(303/3 657),其中蔬菜和粮食中超标率较高,分别为25.3%(135/534)和12.3%(68/551)。结论 河南省部分食品中铅、汞污染情况较为严重,其中粮食、蔬菜和肉类食品中污染情况尤为突出,需要加强监管。     

Moulds and mycotoxins in sorghum stored in traditional containers in India

Various traditional containers have been used in India for storage of sorghum grains. Sorghum is susceptible to fungal infestation and toxin elaboration. The present study relates to the mould and mycotoxin contamination (aflatoxin B₁ and T-2 toxin) in stored sorghum in different storage containers viz. “Kotlu” (Storage rooms), earthenware pots, gunny bags and reed baskets. Aspergillus sp. and Fusarium sp. were the prominent genera and the “Kotlu” form of storage was most susceptible to fungal attack. Storage treatment had little effect on fungal contamination, but despite the fungal infestation, the mycotoxin contamination was found to be very low.     

中国固态发酵白酒中功能细菌研究进展

细菌是白酒酿造3大类微生物之一,其在白酒生产中有着重要的作用,如:芽孢杆菌、乳酸菌、放线菌和梭菌等,它们能产生酯类、有机酸、吡嗪、萜烯等微量成分,从而影响白酒的风味与品质。基于细菌在白酒中的重要功能以及微生物分离培养技术和分析检测技术的进步,近年来相关研究越来越深入。该文综述了近年来白酒功能细菌的研究进展,介绍了酿酒各个环节中主要功能细菌及其在白酒中的作用,旨在为白酒功能细菌的研究提供参考。     

2010年山西省食品中食源性致病菌监测分析

目的 了解山西省食源性致病菌的污染现状.方法 按照2010年度《全国食源性致病菌监测工作手册》进行.结果 1 576份样品中共检出阳性菌株149株,检出率为9.45％,其中单核细胞增生李斯特氏菌、副溶血性弧菌污染比较严重,总检出率为9.50％和8.22％,金黄色葡萄球菌、阪崎肠杆菌和沙门氏菌的总检出率分别为3.02％、1.11％和0.87％.不同类别食品中致病菌的检出率差异较大,生肉中致病菌的检出率高居榜首为49.33％,主要污染菌为沙门氏菌、单核细胞增生李斯特氏菌;沙拉中致病菌的检出率为17.39％,主要污染菌为单核细胞增生李斯特氏菌、金黄色葡萄球菌;生食水产品中致病菌的检出率为16.94％,主要污染菌为单核细胞增生李斯特氏菌、副溶血性孤菌;熟肉制品中致病菌的检出率为9.84％,主要污染菌为单核细胞增生李斯特氏菌、金黄色葡萄球菌、沙门氏菌;中式凉拌菜中致病菌的检出率为8.89％,主要污染菌为金黄色葡萄球菌;鲜榨果汁中致病菌的检出率为6.67％,主要污染菌为金黄色葡萄球菌;鲜冻水产品中致病菌的检出率为5.00％,主要污染菌为副溶血性弧菌;婴幼儿配方粉/米粉/谷粉/豆奶粉中阪崎杆菌的检出率为1.11％.结论 山西省多种食品均存在食源性致病菌不同程度的污染,应加大对散装食品、即食食品和生食水产品的监管.