整鸡中弯曲菌定量检测方法的建立与优化

目的建立一种简便、灵敏、稳定的整鸡中弯曲菌定量检测方法,并用北京地区市售整鸡样品进行验证。方法分别对37株鸡肉中常污染的背景杂菌、24株弯曲菌菌株进行抗生素敏感性测试,对弯曲菌分离用选择性培养基及抗生素添加剂进行优化和改进;用77份人工定量污染弯曲菌的鸡淋洗液进行添加回收实验,以生长指数评价选择性平板对鸡肉样品中背景杂菌的抑制情况和弯曲菌生长状况影响。结果在改良后的Karmali和Preston选择性平板上,弯曲菌生长状态稳定,并可有效抑制鸡肉样品中常见的背景干扰杂菌的生长繁殖,此方法对鸡肉中弯曲菌检出的灵敏度可达2.5 CFU/g。结论所建方法灵敏度高、操作简便、计数准确,Karmali和Preston平板组合后可有效提高鸡肉中弯曲菌的检出率,适用于禽类食品中弯曲菌的定量检测。     

免疫磁珠富集联合荧光定量PCR快速检测牛肉馅中产志贺毒素大肠埃希菌O26∶H11

建立肉制品中免疫磁珠富集(IMS)联合实时荧光定量PCR(qPCR)技术快速检测牛肉馅中产志贺毒素大肠埃希菌(STEC)O26∶H11的方法。方法 建立针对编码O26抗原wzx基因实时荧光定量PCR方法,并验证其特异性和敏感性;人工污染不同浓度STEC O26∶H11的牛肉馅样品,在增菌不同时间后,将增菌液原液、增菌液经免疫磁珠特异性捕获分离物分别进行qPCR检测及平板分离。结果 qPCR检测O26∶H11可产生特异性荧光信号,而23株其他血清型的大肠埃希菌及7株其他种属细菌均未见荧光信号;本方法对纯培养的检测限为5×10^2cfu/ml。人工染菌试验中,当初始染菌浓度达到或高于3×10^2cfu/25g时,增菌培养6h后IMS捕获物可以检测到荧光信号。培养20h后,初始染菌浓度为3SymboltB@10-1 cfu/25g以上,对增菌液直接检测和IMS捕获物检测都可以检测到荧光信号。初始污染浓度较低时,增菌6h后IMS-qPCR的检测灵敏度高于增菌液直接qPCR检测;IMS捕获物涂布显色培养基分离目标菌检测灵敏度高于增菌液直接涂布;CHROMagar STEC显色培养基分离STEC O26∶H11的检测灵敏度高于山梨醇麦康凯培养基(SMAC)。结论 IMS联合qPCR检测食品中的STEC O26∶H11具有特异性强、敏感度高、快速、易操作等特点,可以提高样品中STEC O26∶H11菌的检出率,适用于牛肉制品中STEC O26∶H11的快速检测。     

3M PetrifilmTM检测系统对食品中沙门菌检测的评价研究

目的结合不同标准和规范要求,对Petrifilm~(TM)沙门菌测试片(以下简称3M测试片)进行评价。方法用53个血清型的64株沙门菌及30株不同种属的非沙门菌,对3M测试片的包容性和排他性进行评价;针对12类食品样品,通过与我国国标方法的平行检测,对不同沙门菌检测系统的检验效果进行对比分析。结果 64株沙门菌在所测试4种分离培养基上生长率差异有统计学意义(P0.05),4种沙门菌分离培养基对30株非沙门菌抑制效果也存在一定差异。不同沙门菌选择性增菌肉汤-选择性培养基组合可影响食品样品中10~(-1)cfu/25 g染菌水平沙门菌的检出,差异有统计学意义(P0.05),其中以RV(R10)-3M测试片组合检出率最高,而两种选择性增菌肉汤-选择性培养基组合(如国标法)可提高不同种类食品样品中人工污染低浓度沙门菌的检出。结论 3M测试片以其快速、方便、易保存,且准确性与国标方法相当的特点值得在食品微生物检测行业推广。     

沙门菌、金黄色葡萄球菌、副溶血性弧菌的选择性共增菌培养基的研制

目的 研制一种可同时对沙门菌、金黄色葡萄球菌及副溶血性弧菌进行富集的共增菌培养基SSV,达到同时检测3种食品中常见的食源性致病菌的目的。方法 根据3株菌的营养需求,选择不同的培养基组分进行单因素实验,确定选择性共增菌培养基的配方,通过OD600 nm、受损菌复苏、多重聚合酶链式反应(PCR)、培养基选择性4个方面对SSV培养基进行验证。结果 确定增菌培养基的成分为：蛋白胨10.0 g、KH₂PO₄ 1.5 g、NaCl 15.0 g、LiCl 1.0 g,Na₂S₂O₃ 5.0 g、去氧胆酸钠0.05 g、甘露醇1.0 g、丙酮酸钠5.0 g,蒸馏水1 000 mL。SSV培养基能同时富集以上3株菌,37℃培养16 h后,3株菌的菌体浓度均达到107 CFU/mL及以上;SSV培养基对于受损的目标菌有良好的复苏效果,复苏后OD₆₀₀ nm较于复苏前增长了3倍;同时多重PCR、培养基选择性也得到很好的验证。结论共增菌培养基SSV可用于同时培养沙门菌、金黄色葡...     

不同增菌液对单增李斯特菌的增菌效果比较

目的比较不同选择性增菌液对单增李斯特菌增菌效果及对干扰菌的抗干扰性。方法参考国标GB/T 4789.30-2016和国际ISO 11290-1-2017,将2种来源的单增李斯特菌(标准菌株、分离菌株)和2种干扰菌(大肠埃希氏菌、金黄色葡萄球菌)分别接种到4种不同增菌液中,观察增菌后菌液的生长情况。结果研究发现低浓度菌液(102数量级), Fraser肉汤对单增李斯特菌的增菌效果及抗干扰性优于LB肉汤。选择性添加剂浓度过高会抑制李斯特菌的生长,通过选择合适的选择性添加剂及改变添加剂的浓度可以提高检出率。结论在实验室日常检验过程中,需考虑样品类别,选择合适的培养基。提高检测的准确率。     

食品中热损伤沙门氏菌选择性增菌及实时荧光聚合酶链式反应检测

为了能够高效检测食品中的亚致死损伤沙门氏菌,首先采用热激胁迫的方法得到亚致死损伤沙门氏菌细胞,进而基于选择性增菌培养液SEL建立一种实时荧光聚合酶链式反应检测技术。结果表明：在SEL中经过20h增菌培养后,无论是否经过修复培养,1～2CFU/5mL SEL的亚致死损伤细胞都能得到完全修复并增菌至109CFU/mL水平;依此建立的实时荧光聚合酶链式反应检测技术的纯菌扩增效率为95.41%,检测限为4CFU/反应体系,在人工污染碎食品样品中的检测限为3CFU/10g碎牛肉,而且与传统培养检测方法的结果相吻合。本方法在24h内即可完成食品中热损伤沙门氏菌的修复、选择性增菌以及实时荧光聚合酶链式反应检测,可应用于食品中沙门氏菌污染状况调查及高效检测。     

重组酶聚合酶扩增检测产志贺毒素大肠埃希菌的微流控芯片技术

采用重组酶聚合酶扩增技术（recombinase polymerase amplification,RPA）,开发产志贺毒素大肠埃希菌（Shiga toxin-producing Escherichia coli,STEC）的等温检测方法,结合圆盘式微流控芯片快速检测目标微生物。以stx1和stx2基因为靶点,设计和筛选适宜的RPA检测引物和探针序列,验证了19 株STEC菌株（含9 种stx基因亚型）和21 株非STEC菌株,并采用人工污染的牛肉样品对集成化的微流控芯片进行评价。筛选出检测stx1和stx2基因的高特异性引物、探针组合,与美国农业部微生物实验室技术指南中STEC定量聚合酶链式反应（real-time polymerase chain reaction,real-time PCR）方法相比,目标基因检测的包容性和排他性均为100%。荧光RPA微流控芯片法在20 min内可同时进行32 个反应,可检测STEC菌体灵敏度为9.5×103 CFU/mL。根据GB 4789.6—2016《食品微生物学检验 致泻大肠埃希氏菌检验》的规定经增菌培养后在人工污染牛肉样品中可检测1 CFU/25 g的STEC污染,方法的相对正确度和相对检出水平均为100%。本研究开发了一种荧光RPA微流控芯片检测方法,可检测常见stx基因亚型STEC菌株,操作简单、反应速度快,适用于STEC的高通量快速检测。     

PCR-核酸试纸条法检测食品中假结核耶尔森菌

目的 建立一种基于PCR-核酸试纸条技术快速检测食品中假结核耶尔森菌的方法。方法 将10株假结核耶尔森菌株和9株其他耶尔森氏菌及18株来源菌株作为实验菌株进行特异性实验; 通过纯菌液计数、干扰菌实验检测进行灵敏度验证。结果 DNA检测可达到10?3 μg/mL, 25 g样品加菌实验灵敏度可达 100 CFU/25 g, 添加10倍干扰菌不会降低检测灵敏度。利用建立方法对市场购买的食品进行筛查并与国标方法进行比较, 建立方法的灵敏度优于国标方法。结论 该方法检测结果准确, 灵敏度高, 适用于检测食品中假结核耶尔森菌。     

LAMP实时浊度法快速检测食品中产志贺毒素大肠埃希氏菌

针对产志贺毒素大肠埃希氏菌(Shiga toxin-producing Escherichia coli,STEC)stx1和stx2基因的特异性序列分别设计4条特异性引物,采用环介导等温扩增(loop-mediated isothermal amplification,LAMP)技术,利用实时浊度仪建立食品中STEC的LAMP实时浊度法快速检测方法。LAMP反应在实时浊度仪63℃恒温下1 h可完成。对方法的特异性、灵敏度、稳定性进行了评价,并在实际样品检测中进行应用。经优化该方法的检测灵敏度可达150拷贝/反应,4株STEC菌株LAMP扩增结果与其基因型一致,其他21株非STEC菌株均未出现非特异性扩增。395份食品样品检出STEC阳性68份(阳性率为17.2%),所检食品类别中畜产品阳性率最高(达31.3%),禽产品、水产品和可生食蔬菜均有少量阳性样品检出,阳性样品中以stx2基因阳性型为主。结果表明,LAMP实时浊度法具有快速、灵敏、特异性强、操作简便的优势,适用于食品中STEC的快速筛查。     

实时荧光定量PCR法快速检测食品中大肠埃希菌

目的应用实时荧光定量PCR技术,结合3~5 h的前增菌处理,建立食品中大肠埃希菌的快速、灵敏、定量的检测方法。方法以大肠埃希菌(ATCC 25922)为参考菌株,对培养基和培养温度进行优化,选择最佳的前增菌培养条件。将不同浓度的参考菌株和样品分别接种前增菌液中培养3~5 h。采用Triton-X 100提取增菌后的DNA,实时荧光定量PCR扩增大肠埃希菌特异性片段。所得Ct与对应的原始(增菌前)参考菌株的浓度,建立标准曲线,计算样品中大肠埃希菌的数量。结果纯培养模式下,经过3、4和5 h的前增菌后,标准曲线具有很好的线性,r2分别为0.996、0.992和0.991,对应的检测限为136、14和1.4 cfu/100 ml;含杂菌培养模式下,NB和EC肉汤42.0℃增菌4 h后,建立的标准曲线r2分别为0.972和0.978。在不同食品中该方法的加标回收率为74.0%~174.0%。结论 3~5 h的前增菌实时荧光定量PCR方法可以快速、灵敏、定量地检测食品中活的大肠埃希菌。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Review of techniques to manufacture micro-hydrogel particles for the food industry and their applications

Microgels are ‘soft’ microscopic cross-linked polymeric particles that are being increasingly exploited in a variety of industries for rheology control, encapsulation and targeted delivery. They are valued because of the ability to tune their functionality to address specific applications in oil recovery, coatings, drug delivery, cosmetics, personal care and foods. Food microgels are typically biopolymer hydrogels in the form of microspheres, nanospheres (also called nanogels), spheroids and fibres. The utilisation of engineered microgels in foods has so far been limited, despite their great potential to address several needs in the food industry, including: satiety control, encapsulation of phytonutrients and prebiotics, texture control for healthier food formulations (e.g. reduced fat products), and targeting delivery to specific areas in the digestive tract. We review the scientific and patent literature on the utilisation and manufacturing methods for producing microgels with an emphasis on micro-hydrogels for food applications.     

12—A CRITIQUE OF SOME HYPOTHESES RELATING TO THE HETEROGENEITY OF THE HIGH-SULPHUR PROTEINS OF WOOL

Joubert and Burns prepared a large number of fractions from the high-sulphur proteins of wool and estimated their molecular weights and amino-acid compositions. Their data have been re-examined in order to look for statistically significant interrelations between amino acids and between the proportion of various amino acids and molecular weight. Statistical analysis of the data is also used to examine the credibility of some hypotheses concerning the mechanism of keratin biosynthesis and to provide further evidence for the existence of families of proteins within the high-sulphur fractions of wool.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of     

The Latest Data about Development of Chinese Printing Industry in 2013

In the 2014 China（Shanghai）International Printing Week,Director Wang Yanbin released the latest data about development of Chinese printing industry in 2013.According to statistics,in 2013,the total output value of Chinese printing industry exceeded 1trillion Yuan for the first time,reaching 1.03985 trillion Yuan.There were 105,000 printing enterprises in China,employees were 3.415 million.The total asset was 1.06247 trillion Yuan;     

The State Council Issued "Directory of Government Approved Investment Projects(2013 Edition)"

正On December 2nd,2013,the State Council issued the notification of"Directory of Government Approved Investment Projects(2013 Edition)"(hereafter referred to as"notification").It is pointed out in the"notification"that in order to further deepen reforms in investment systems and administrative examination and approval systems,simplify administrative procedures and delegate powers to lower levels,earnestly     

China textile machinery: taking off in progress

正Among the 1600 exhibitors who take apart in the ITMA ASIA+CITME2014 2/3 are Chinese manufactures.If the numerous figures failed to attract your attention,the increase of quality should draw your focus.To adopt the demand of developing textile machine market,domestic textile machinery enterprises now follow the slogan of"technology drives development"to enhance product competitiveness.Our domestic sellers will showcase product ranging from spinning,weaving,dyeing and printing,     

Top Ten News of China's Paper Industry 2013

On December 24th, 2013, the meeting on the selection of top 10 news of China＇s paper industry 2013 sponsored by 〈China Paper Newsletters〉 was held in Beijing. The yearly selection of the top l0 news, which began in 2000, has become a brand activity widely recognized in the industry thanks to the support from the authorities at all levels and public participation.