香菇中不同形态甲醛的测定与分析

香菇中同时存在游离态甲醛和结合态甲醛,建立一种可以一次性快速测定这两种形态甲醛含量的方法。根据香菇中两种形态的甲醛析出条件,实验设计了2个步骤:第一步,先通过蒸馏提取香菇中游离态甲醛;第二步,加酸后再次蒸馏,提取香菇中结合态甲醛。实验设定条件为:蒸馏时间为4 min,加10%磷酸40 mL,水浴温度为60℃,水浴时间为60 min。结论为,当甲醛浓度为0.0～10.0 mg/L时,标准曲线线性关系良好,相关系数r为0.9995,游离态甲醛检测的加标回收率为87.8%～105.9%,相对标准偏差(RSD)在3.5%～7.0%;结合态甲醛检测的加标回收率为89.5%～105.8%,相对标准偏差(RSD)在2.5%～6.7%。香菇中结合态甲醛含量占总甲醛的62.6%～71.8%,游离态甲醛和结合态甲醛在伞部的含量均高于柄部的含量。全自动定氮仪可以一次性处理香菇中不同形态的甲醛,与高效液相色谱联用,能够自动、快速、高效地完成香菇中甲醛形态的检测与分析。     

定氮仪代替传统蒸馏联合滴定法测定干菊花中的二氧化硫含量

目的建立利用全自动定氮仪代替传统蒸馏联合滴定法检测干菊花中二氧化硫含量的方法。方法利用全自动定氮仪封闭蒸馏干菊花,用乙酸铅吸收二氧化硫蒸馏液,并利用碘标准溶液滴定,测算出二氧化硫的含量,同时对蒸馏时间、加酸种类及含量进行优化。结果优化后干菊花中二氧化硫的检测条件为添加盐酸量10 m L、蒸馏时间8 min,得到的蒸馏液再进行滴定。经检测,杭白菊中二氧化硫含量为55.19~139.24 mg/kg,加标回收率为84.9%~102.3%。结论利用定氮仪代替传统蒸馏能够大大节省检测时间、且安全可靠、重复性好,适合于干菊花中二氧化硫的检测。     

香菇中甲醛的提取及其乙酰丙酮分光光度法测定

本文采用乙酰丙酮分光光度法测定香菇在不同温度下浸泡不同的时间的浸出液中甲醛的含量,方法在甲醛含量为0.5-5mg/L范围内呈良好的线性(r2=0.9998)。实验结果表明,用60℃的水浸泡40min或40℃的水浸泡60min可最大限度地浸出香菇中的甲醛。     

鲜香菇在不同处理方式下的甲醛含量分析研究

目的检测分析经匀浆、干燥等方式处理鲜香菇中的甲醛含量,反映处理后鲜香菇的生物活性随时间的变化情况,为香菇的储存提供数据支持。方法利用液相色谱法测定香菇甲醛含量。结果匀浆后的鲜香菇中甲醛含量随时间增长而降低,至腐烂后消失。真空包装经高燥处理的香菇中甲醛含量随时间增长呈上升趋势,而真空包装未经干燥处理的香菇,其甲醛含量呈下降趋势。结论通过连续检测鲜香菇中的甲醛含量,验证了香菇中的甲醛来源于其生理活动这一科学论断。基于此,通过检测香菇的甲醛含量判断香菇得生物活性,以观察香菇在贮藏及运输过程中的保质效果。     

乙酰丙酮分光光度法测定白菜中甲醛含量的方法优化及其在快检结果验证中的应用

目的建立乙酰丙酮分光光度法测定白菜中甲醛含量的方法,并用此方法验证甲醛速测盒的检测结果。方法以甲醛含量为指标,研究样品浸泡时间、加蒸馏水量、加磷酸量、蒸馏时间等前处理条件和显色时间、水浴时间、加乙酰丙酮量等测定条件对白菜中甲醛测定结果的影响。以大白菜为试样,对比乙酰丙酮分光光度法和甲醛速测盒的检测结果。结果白菜中甲醛含量测定的最佳的条件为样品浸泡时间35 min,加水量160 m L,磷酸添加量5 m L,蒸馏时间80 min,乙酰丙酮添加量1 m L,水浴时间5 min,显色时间15 min。在此条件下,白菜中甲醛回收率为95.2%～99.7%。甲醛速测盒的结果与之比对,结果一致。结论乙酰丙酮分光光度法结果准确,适合用于大白菜中甲醛的测定,实验中所用甲醛速测盒与之结果一致,可以快速有效测定白菜中甲醛含量。     

高效液相色谱法测定食品中甲醛次硫酸氢钠含量

目的建立高效液相色谱法检测食品中的甲醛次硫酸氢钠含量。方法样品经磷酸溶液提取,残留在其中的甲醛次硫酸氢钠分解释放出甲醛,甲醛与衍生试剂2,4-二硝基苯肼发生反应,生成黄色的衍生物苯腙,经Eclipse XDB-C_(18)(250 mm×4.6 mm,5μm)色谱柱分离,流动相为乙腈-水(60:40,V:V),柱温为35℃,流速为1.0 m L/min;检测波长为355 nm,经高效液相色谱仪检测。结果本方法优化的实验条件是:磷酸溶液浓度2.0%,衍生剂2,4-二硝基苯肼溶液的浓度为2.0%,60℃水浴中反应30 min;甲醛标准溶液在0~3μg/m L浓度范围内具有良好的线性关系(r=1.00);在5、10和30μg 3个加标水平上的回收率为95.36%~98.20%,相对标准偏差为0.403%~1.05%;检出限为0.17 mg/kg。结论本方法快速准确,适合于测定食品中甲醛次硫酸氢钠的残留量。     

京畿地区香菇中甲醛含量检测及分析

目的通过分析京畿地区产地香菇和市场香菇中的甲醛含量,揭示不同种类、干湿形态、生长阶段、培育方式的香菇中甲醛含量变化,为香菇中的甲醛本底含量研究提供数据支持。方法利用乙酰丙酮分光光度法测定香菇甲醛含量。结果 (1)鲜香菇中甲醛含量差异较大,部分高达200倍左右;(2)鲜香菇中中菇含量最高,总体呈中菇大菇小菇趋势;(3)不同生长阶段的香菇中3潮或4潮的甲醛含量较高,与香菇发育完全、代谢旺盛有关;(4)地栽方式培育的香菇其甲醛含量一般是架栽的2倍左右;(5)参照出口香菇中甲醛限量标准,部分鲜香菇中的甲醛含量会对出口造成一定影响。结论栽培工艺、菌种类型对香菇中内生甲醛含量有着决定性影响,应加强对比,进行交叉试验,优化培育方式,遴选香菇菌种,降低香菇内生甲醛的含量。     

鲜香菇中甲醛含量的连续监测分析

目的对河北和北京2个地区来源于市场和生产基地的鲜香菇中的甲醛含量进行连续监测,探究鲜香菇中甲醛含量随时间的变化规律。方法利用高效液相色谱法测定香菇样品中的甲醛含量,并对不同来源样品中的甲醛含量进行对比分析,分析造成含量不同的原因。结果来源于多个产地的北京市售鲜香菇中的甲醛含量较河北市售鲜香菇高;规范管理条件下的鲜香菇中的甲醛含量相对较高,生长态势较好。结论对鲜香菇中的甲醛含量进行持续监测对于监控市场鲜香菇的质量变化、预测预防香菇生产过程中可能出现的病害或误操作等问题具有较强的现实意义。     

柱前衍生高效液相色谱法测定5种常见食用菌中的甲醛含量

目的建立柱前衍生-高效液相色谱法测定5种常见食用菌中甲醛含量。方法将干制与新鲜食用菌用超纯水浸泡,浸泡液经2,4-硝基苯肼(DNPH)衍生后,采用高效液相色谱法检测;色谱柱:C18(250mm×4.6mm,5μm),流动相:乙腈-水(70:30, V:V);流速为1.0 mL/min;检测波长352 nm;柱温40℃。外标法定量测定食用菌中甲醛含量。结果柱前衍生法对甲醛浓度在10.70～214.00μg/L范围内与其衍生物峰面积呈良好的线性关系,线性回归系数(r~2)为0.9964,方法的检出限为4.20μg/kg(S/N=3)。加标回收率为78.27%～114.26%,精密度1.55%～9.22%(n=6)。5种食用菌样品仅香菇样品检出甲醛。新鲜香菇甲醛含量超标,干制后香菇甲醛含量降低,低至国家标准含量以下。结论本研究的方法简便、快速、准确、稳定,可用于测定食用菌中甲醛含量。     

液相色谱法检测与乳制品中甲醛的含量

为了建立一种快速准确检测乳与乳制品中甲醛含量的方法,本文采用沉淀蛋白的方法,然后对处理样品利用2,4-二硝基苯肼对甲醛进行衍生,通过液相色谱仪检测,回收率在90．64～108．41％之间,均能满足仪器法检测乳与乳制品甲醛含黾的要求。     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.