漂液有效氯的得率到底是多少

在计算漂液中有效氯得率的问题上,有的厂根据在制漂液时烧碱与氯反应,认为理论上有效氯的得率为制漂液时用氯量的50%,除去制漂液时通氯损失和副反应,实际得率下降到45%左右。但根据所制出的漂液,取样化验和计算,得出有效氯的得率为制漂用氯量的90%左右。问题出在哪里呢? 在制取次氯酸钠漂液时,烧碱与氯进行反应,生成次氯酸钠漂液。其化学反应方程式如下: Cl_2 2Na0H=NaClO NaCl H_2O     

荷兰豆嫩荚干制品的生产工艺优选

通过单因素实验法和正交实验法确定合适的烫漂温度、烫漂时间、烫漂液和浸护液配方;通过比较产品色泽和复水比选择理想的干制工艺。研究表明,烫漂液中添加3%的食盐、200mg/L的柠檬酸和400mg/L的D-异抗坏血酸钠;烫漂温度95℃、烫漂时间为4min;浸护液采用10%糊精、10%蔗糖、5%食盐的配方;用真空干燥法得到的荷兰豆嫩荚的干制品色泽及综合品质最好。     

用液氯制漂液判断终点的方法

目前,国内大部分制浆造纸厂采用次氯酸钙漂白,制备次氯酸钙漂液,是往石灰乳液中通氯。如何控制通氯终点呢?目前国内大、中专所用的教材中,大致有两种叙述方法。一种是:将酚酞试液作指示剂滴于漂液的液面,在3秒种内不褪色即为终点;另一种是:控制漂液加入的酚酞指示剂褪色时间以3秒为终点。有人认为这两种叙述相矛盾,其实这两种叙述是一致的,只是都不太完整。确切的叙述应该是这样的:操作中用酚酞指示剂滴于漂液的液面,若恰好为通氯点,则漂液应显红色,3秒钟内红色不褪,而到达3秒钟时红色应立即消失。     

制漂液喷射器──混合器的结构对氯气有效利用率的影响

纸浆的漂白，在大力推广无氯漂白的新工艺前题下，目前多数纸厂因受设备投资的限制，仍然以氯气制漂液漂白为主。在原有制漂液设施基础上，怎样提高氯气制漂液和氯气有效利用率，降低氯气用量，降低生产成本，提高经济效益，减轻环境污染，就显得非常重要。笔者经过多年的生产试验和几十个造纸厂，漂液制备工艺方法的改进，总结归纳为四种方法进行对比如下表１． 氯气制漂液转化率高，不能表示氯气有效利用率高，要看制成的漂液是否稳定，澄清贮存时挥发损失率大与小，是否有利于吨浆漂白氯气用量的降低。所以氯气的转化率不能作为一个厂对…     

洗漂过程对棉浆黏度影响因素的研究

以蒸煮后棉浆为研究对象,通过正交实验确定最佳洗涤参数,探讨了在该洗涤条件下残氯、Ca~(2+)、Na~+浓度对棉浆黏度的影响,并采用R5法自制Cl O_2漂液,进一步分析漂白阶段漂液浓度对棉浆黏度的影响。结果表明,洗涤中各参数对棉浆黏度影响的顺序为:残氯浓度Ca~(2+)洗涤时间p H值。在残氯浓度为0.036 g/L,Ca~(2+)浓度为90 mg/L,洗涤时间为1 h,p H值为7时洗涤最佳。通过改变洗涤参数中残氯浓度,发现随着残氯的增加,棉浆黏度的下降率呈先下降后上升趋势,其下降率的最小值为11%;同时,调整Ca~(2+)浓度,发现在Ca~(2+)为110 mg/L时棉浆黏度下降率最低。另外,洗涤过程中添加Na Cl,可使棉浆黏度下降率达2.2%;改变漂白阶段漂液浓度,使得棉浆黏度下降率为2.1%。     

芒果真空冷冻干燥工艺的研究

以百色象牙芒为原料,采用真空冷冻干燥的方法,对芒果干燥过程的漂烫工艺、护色工艺以及真空冷冻干燥的参数控制等问题进行研究。结果显示:沸水烫的温度为95℃,漂烫时间为45s时,漂烫效果最好;0.30mol/L×10-3苹果酸和0.20mol/L×10-3抗坏血酸的复合液,护色时间10min,复合液pH3.5,此时的护色效果最佳;干燥过程分为升华干燥阶段和解析干燥阶段,升华干燥阶段,真空度为45~55Pa,加热板温度为35℃;解析干燥阶段,真空度为45~55Pa、加热板温度为55℃,此时干燥的产品品质最优。     

亚麻织物氯漂过程中pH值对有效氯分解率的影响

测定了亚麻织物次氯酸钠漂白过程中有效氯动态分解率,探讨了氯漂工艺中控制有效氯均匀分解的重要性及意义,指出亚麻织物氯漂可以通过控制漂液的ｐＨ值达到控制有效氯分解率的目的。     

染整中疑难问题解答

问1:我厂生产的牛仔服装经酵素石磨氯漂后未发现有黄斑,但一经染色,就会发现面料上有一块一块或大或小的色斑。无论采用均匀升温染色还是直接采用85℃染色,均不能消除此现象,不知是何原因?我厂采用直接染料染色,工艺为:牛仔成衣退浆(85℃×10min 50件/缸,浮石5kg)→酵素(55℃×45min)→氯漂(40℃)→脱氯→过水。染色:将成衣投入化好料的机内转动染色→过水→固色→柔软→烘干。(南京汇达服装有限公司水洗厂)     

烟草温室营养液无土育苗技术的试验研究

烟草营养液无土育苗技术的试验研究,包括施肥技术、育苗盘选择和修剪技术。试验结果表明,育苗期间营养液的氮素浓度前期以100×10-6~125×10-6为宜,后期以125×10-6~200×10-6为宜;无磷或前期缺磷会严重影响烟苗的生长发育;育苗盘孔径大小(苗穴数目)不同,育成烟的茎基直径、根系鲜重、根系于重、地上部鲜重等不同,以200号盘的数值为最高,200号盘与288、338和392号盘有显著差异;修剪以苗高达8cm时为第一次修剪期,每次修剪间隔5天,修剪的高度以距生长点4~5cm为宜。      

氨基磺酸用于龙须草浆漂白

氨基横酸（SA）是一含氮助剂，可溶于水，105℃时分解。在次氨酸盐溶液中易分解成硫酸和氮气，所以不能将其直接加入漂液，应先用水溶解后再加入漂液中。氨基磺酸能使漂液保持稳定．减少重金属离子对纤维素的氧化降解。与漂液反应生成的N一氯氨基磺酸钠能对纤维素的反应基团产生固定作用，阻止纤维素的剥皮反应，从而提高了纸浆强度、白度，同时，还可依次氯酸盐漂白在pH值小于7的情况下进行，进而加快漂白速度。轮厂体用氯甚碘酸化湮内助剂，达到了预期目的。左表是漂白烧碱一首酿法龙须草浆时使用氨基磺酸前后的结果对比。加入SA时，先…     

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.