海水预处理及脱硼研究

利用一种低成本、高效的反渗透海水淡化预处理方法——碱化絮凝法,对海水进行预处理及脱硼处理,采用石灰乳作为碱化剂,考察了pH,温度,慢搅时间,静沉时间对脱硼效果的影响.并用正文实验的方法,确定了最佳脱硼率.结果表明,pH= 10.8,温度25℃,慢搅20 min,静置5h,脱硼效果最好,脱硼率为86.5％,余硼含量达到0...     

海水预处理氢氧化镁浆料制备及对硼吸附研究

研究了在海水脱硼预处理中浆料氢氧化镁的制备,考察了不同pH值、絮凝剂加入量、静置时间和慢搅时间对氢氧化镁浆料含量的影响,确定了最佳浆料制备条件,并探讨了碱化絮凝过程的中间产物Mg( OH)2对硼的吸附热力学和动力学研究.结果表明,Mg(OH)2对硼具有较强的吸附能力,吸附过程符合Langmuir等温吸附模型和Lagergren准二级动力学模型.     

聚硅酸聚合氯化铁的海水絮凝条件研究

海水淡化作为一种新的水源,正显示出独特的优势和良好的前景.文章使用自制的聚硅酸聚合氯化铁絮凝剂,对海水进行预处理,研究了海水絮凝条件.实验结果表明,每100ml的海水中加入0.1ml的聚硅酸聚合氯化铁絮凝剂,海水温度23℃～33℃,pH值3～10,快搅(250r/min)1min,慢搅(75r/min)16min,海水除浊率达95%以上,海水预处理效果较佳.     

海水淡化预处理的碱化絮凝研究

石灰乳作为碱化絮凝海水淡化技术的重要助剂,其品质对预处理效果至关重要.与烧碱、氨水等碱化剂不同,石灰乳具有碱化率高,用药量少,价格低等优势.文中将石灰乳熟化工艺分为两个阶段,得到两个阶段的最佳熟化条件,并根据碱絮凝海水淡化预处理的需要,分别用清水和海水进行熟化,比较各种熟化条件下石灰乳的碱化性能.     

深层海水浓缩液中硼的吸附工艺研究

文章重点研究了螯合型树脂(D403)吸附深层海水浓缩液中硼的工艺参数及吸附特性,并考察了反应时间、起始浓度、pH值等因素对D403树脂脱硼性能的影响.结果表明:D403树脂对溶液中的硼具有较强的吸附能力,pH值改变对树脂的吸附能力有一定影响,碱性环境利于硼的吸附;树脂对硼的吸附率最大可达96.33％.     

柚皮苷酶在蜜柚酒中的脱苦效果研究

通过单因素试验和正交试验考察酶制剂的处理时间、处理pH值、处理温度等对蜜柚酒的脱苦效果,通过对比而选出最优脱苦方法。结果表明,柚皮苷酶对蜜柚酒脱苦的最佳工艺条件为,酶制剂在发酵后添加效果较好;当添加量为0.5 g/L时,pH值6、温度50℃、作用时间30 min,果酒的脱苦率可达48.89%。     

壳聚糖处理棉织物的紫草染色性能研究

针对紫草天然染料上染棉织物时存在上染率低、色牢度差的问题,研究了利用壳聚糖对棉织物进行预处理,再用紫草天然染料进行染色的工艺。探讨了壳聚糖处理液用量、浸渍温度和浸渍时间对预处理效果的影响,以及染色pH、染色温度、染色时间对预处理棉织物K/S值的影响;分析了染色棉织物的染色牢度和紫外防护性能。结果表明:壳聚糖对棉织物的最佳预处理工艺为:壳聚糖处理液质量分数45%、浸渍温度80℃、浸渍时间20 min;预处理棉织物最佳染色工艺为pH 6、染色温度60℃、染色时间30 min。壳聚糖预处理后棉织物的染色深度、染色牢度、抗紫外线性能均得到改善。     

去除腐乳中蛋白质的方法研究

为脱去腐乳中的蛋白质,实验分别选取盐酸法、三氯乙酸法及Sevag法三种方法,确定最佳脱蛋白方法并对其影响因素溶液pH、溶解时间、溶解温度进行研究,得出最佳的脱蛋白方法为盐酸法,其最适pH值为3.5,最适溶解时间为0.5h,最适溶解温度为35℃,脱蛋白率可达62.1%。     

铝单宁交联对超细纤维合成革性能的影响

采用甲酸预处理和铝单宁交联的方法对超细纤维合成革进行改性,以提高超细纤维合成革的染色性能及透水汽性.通过考察甲酸用量、甲酸预处理时间、铝单宁用量、交联时间、交联温度及改性pH值等因素对合成革基布上染率及透水汽性的影响,优化了预处理和铝单宁交联的工艺条件,即:甲酸用量3%、预处理时间60 min、铝单宁用量6%、交联时间60 min、交联温度50 ℃、交联pH值为6.     

水酶法提取核桃油工艺的研究

为了改进水剂法提取核桃油的工艺,探讨了酶用量、搅油温度、搅油时间、pH值对出油率的影响。通过单因素和正交优化试验确定最佳工艺条件为:酶用量17500U/100g料浆、搅油温度55℃、搅油时间3h、pH4.5,其出油率可达77.34%。研究发现,低温贮藏可明显降低水酶法提取工艺的出油率。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

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

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.