咔唑比色法测定剑麻果胶含量

采用咔唑比色法测定剑麻果胶粉中果胶含量的方法,对其测定条件作了详细的试验,获得了较佳的测定条件:浓硫酸用量为6.0mL,水解温度为70℃,水解时间为20min,0.15%咔唑无水乙醇溶液用量为0.5 mL,在室温下显色,显色时间为30min.用于实际样品的测定时,结果较为满意.     

咔唑比色法测定豆腐柴叶果胶含量的研究

介绍了采用咔唑硫酸分光光度法测定豆腐柴叶果胶粉果胶含量的方法,对其测定条件作了详细的试验,获得了较佳的测定条件浓硫酸用量为5.0mL,水解温度为75℃,水解时间为15min,0.15%咔唑无水乙醇溶液用量为0.2mL,显色温度为25℃左右,显色时间为2h。用于实际样品的测定时,结果较为满意。     

罗汉果果胶含量测定方法的研究

研究对生产罗汉果甜甙所产生废液废渣果胶含量的测定方法。重点研究重量法、原子吸收光谱法和咔唑硫酸比色法三种对果胶含量的测定方法。结果表明:与重量法和原子吸收光谱法相比,咔唑硫酸比色法简单准确,显色稳定,灵敏度高,重现性好,稳定性高,而且大大缩短测定时间,有利于测定过程的分析与控制。     

咔唑比色法测定苹果渣提取液果胶含量的研究

介绍了采用咔唑硫酸分光光度法测定苹果渣中果胶粉果胶含量的方法，对其测定条件作了详细的试验，获得了较佳的测定条件：浓硫酸用量为12．0mL,水解温度为90℃，水解时间为10min，0．15％咔唑无水乙醇溶液用量为0．2mL，显色温度为25℃左右，显色时间为2h。用于实际样品的测定时，结果较为满意。     

烟草中果胶含量连续流动测定方法的改进

对烟草果胶含量测定的连续流动法进行了改进,通过酸性醇溶液除杂、弱酸提取和间羟基联苯法显色,快速测定了烟草中的果胶含量。结果表明:①除杂过程中,组分损失率小于0.2%;②样品前处理所需时间仅3 h;③试样稳定性高,48 h内检测结果的相对变化率小于1%;④小分子糖对果胶检测结果的影响小于0.3%;⑤方法回收率为96%~104%。     

酶解-流动分析法测定烟草中的果胶含量

建立了一种测定烟草中果胶含量的酶解-流动分析仪法,并对酶解条件进行了优化。即样品经80%乙醇回流抽提后,在58℃、60mL pH 4柠檬酸三钠/柠檬酸缓冲溶液中用480u/g果胶酶酶解2h,用流动分析仪测定酶解液中的果胶含量(以半乳糖醛酸计)。该法的线性相关系数为0.9997,回收率96.8%~101.0%,RSD为1.70%。     

豆腐柴叶果胶提取液中果胶含量的快速测定

目的建立快速测定豆腐柴叶果胶提取液中的果胶含量的方法。方法采用咔唑硫酸分光光度法直接测定果胶提取液中的果胶含量,测定结果再用校正因子校正。结果校正因子为0.8551,本方法相对标准偏差小于3.5%,精密度、灵敏度较高。结论此法可快速测定豆腐柴叶提取液中的果胶含量,缩短了分析时间,有利于生产过程的控制。     

响应面法优化籽瓜皮中高纯度果胶的提取工艺

利用响应面法优化籽瓜皮中高纯度果胶的提取工艺条件,以半乳糖醛酸的含量为果胶纯度的评价指标,采用咔唑-硫酸比色法测定果胶中半乳糖醛酸含量。在单因素试验的基础上,选择提取温度、提取时间和提取液pH值等因素进行响应面试验设计。结果表明,果胶提取最佳工艺条件为提取时间150 min、提取温度88 ℃、提取液pH值为1.6、料液比为23∶1(g∶L)。优化工艺所提取果胶中半乳糖醛酸含量理论值为78.03%,实测值为76.65%,实际测定值与理论计算值基本吻合。     

酶解-流动分析法测定烟草中果胶前处理方法的改进

为提高烟草中果胶的分析速度,对酶解流动分析法中烟叶的前处理过程进行了改进,即用5%醋酸溶液萃取代替80%乙醇溶液回流抽提除去烟末中的水溶性糖,并采用两种方法同时测定了20个烤烟烟叶样品中的果胶含量.结果表明:①改进法果胶的回收率为99.5%～105.7%,变异系数2.08%;②改进法的检测结果稍高于原方法,但二者没有显著性差异.     

红麻粗纱酶解效果测定及其分析

对红麻韧皮纤维经生物酶一浴法脱胶改性处理后,运用咔唑比色法测定红麻粗纱果胶和木质素的残留量,定量测定果胶的去除率。分析了酶浓度、温度、pH值和作用时间对酶解后果胶及木质素去除率的影响。实验表明,复合酶对红麻粗纱中果胶和木质素去除效果较好,所得纤维质量明显改善。     

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.