丁二酰化香蕉纤维素对Pb~(2+)的吸附性能及其结构表征

研究了丁二酸酐修饰的香蕉纤维素对水溶液中Pb~(2+)的吸附特性,明确改性香蕉纤维素吸附剂的添加量、溶液pH值、温度及Pb~(2+)初始质量浓度对吸附效果的影响,并探讨吸附过程的动力学特征。结果表明,改性香蕉纤维素对Pb~(2+)吸附的最佳pH值为5.0,单位吸附量随吸附剂添加量的减小、Pb~(2+)初始质量浓度的增加而增加。在优化试验条件下,1 g/L的吸附剂在30℃时,对pH5的50 m L 100 mg/L Pb~(2+)溶液中,单位吸附量达到44.3 mg/g。改性香蕉纤维素对Pb~(2+)的吸附动力学模型符合准二级动力学模型,拟合系数在0.999以上。结合傅里叶红外光谱、扫描电镜-热重分析和X射线衍射分析手段,发现改性香蕉纤维素对Pb~(2+)的吸附以物理吸附为主,同时包括螯合作用、离子交换等化学吸附及颗粒内扩散等过程。     

荆树皮栲胶/纤维素-聚乙烯亚胺气凝胶吸附阿散酸的研究

以纤维素为原料,采用NaOH/尿素/水混合溶液溶解纤维素,通过溶胶-凝胶法将荆树皮栲胶（BWT）和聚乙烯亚胺（PEI）接枝到纤维素上以制备荆树皮栲胶/纤维素-聚乙烯亚胺气凝胶（（Cell/BWT）@PEI）,通过扫描电子显微镜（SEM）、比表面积（BET）分析、热分析（TG-DTG）等手段对其进行结构表征和性能分析,并且研究了其对阿散酸（p-ASA）的吸附性能。结果表明,（Cell/BWT）@PEI比表面积为190.5 m2/g,孔径为15.2 nm,具有较好的热稳定性;当p-ASA初始质量浓度为100 mg/L、溶液pH值为5.0、吸附时间为360 min、吸附温度为25℃、（Cell/BWT）@PEI投加量为0.4 g/L时,（Cell/BWT）@PEI对p-ASA的平衡吸附容量（Qe）为163.3 mg/g,去除率为65.3%;(Cell/BWT)@PEI对p-ASA的吸附为化学吸附,Freundlich等温吸附方程更适于描述（Cell/BWT）@PEI对p-ASA的吸附,且吸附过程自发进行;吸附再生实验结果表明,循环再生5次后,（Cell/BWT）@PEI对p-ASA的Qe为1...     

含硫改性壳聚糖/NCC复合气凝胶的制备及其在废水中应用

本文以纳米结晶纤维素(NCC)和含硫改性壳聚糖为原料,合成含硫改性壳聚糖气凝胶和含硫改性壳聚糖/NCC复合气凝胶。通过扫描电镜(SEM)和比表面积(BET)对两种气凝胶的形貌和结构进行了分析;并通过改变溶液的pH值、初始浓度、吸附时间和吸附剂用量等吸附条件,探究了气凝胶对Hg~(2+)的吸附情况。实验结果表明,与含硫改性壳聚糖气凝胶相比,复合气凝胶的比表面积增大了10.37%;在pH为5、吸附剂用量30.0 mg和Hg~(2+)溶液初始浓度为100mg/L时,复合气凝胶的最大吸附容量达到最大为242.3 mg/g,比含硫改性壳聚糖气凝胶增加了2.02%;并且复合气凝胶对Hg~(2+)的吸附过程符合准二级动力学模型,同时复合气凝胶能用脱附剂EDTA脱附再生。     

棉秆皮微晶纤维素/β-环糊精气凝胶纤维的制备及吸附性能

棉秆皮微晶纤维素和β环糊精在尿素体系下低温溶解制备纺丝溶液,以湿法纺丝和冷冻干燥法制备棉秆皮微晶纤维素/β-环糊精气凝胶纤维,用以吸附染料废水中的亚甲基蓝。采用单因素方法分析确定了β-环糊精添加量,以及吸附条件对亚甲基蓝吸附量的影响。结果表明：棉秆皮微晶纤维素与β-环糊精质量比为5∶2,吸附温度20℃,吸附时间5 h, pH值=7时,制备的气凝胶纤维吸附效果好;染液质量浓度为50 mg/L时,棉秆皮微晶纤维素/β-环糊精气凝胶纤维对亚甲基蓝的吸附量最大,为56 mg/g;吸附过程符合准二级吸附动力学模型和Langmuir吸附等温线模型。扫描电镜结果说明添加β-环糊精的气凝胶纤维孔径比纯棉秆皮微晶纤维素气凝胶纤维孔径更大,形状更规则,对染料废水中亚甲基蓝的吸附效果更好。     

赖氨酸改性纳米纤维素的表征及其对亚甲基蓝的吸附行为研究

为了制备可生物降解的高效吸附材料,以竹浆纳米纤维素为原料,通过高碘酸钠氧化和Schiff碱反应,得到了赖氨酸改性的纳米纤维素,采用傅里叶红外光谱(FT-IR)、透射电子显微镜(TEM)和热重分析(TG)等表征手段证实了赖氨酸成功引入到纳米纤维素的表面。以亚甲基蓝(MB)为模型物,研究了其吸附性能。考察了吸附剂添加量和溶液pH值对平衡吸附量的影响。结果表明,与纳米纤维素(NFC)、醛基纳米纤维素(NFC-CHO)相比,赖氨酸改性纳米纤维素(NFC-g-Lysine)的吸附能力大幅提高,当NFC-g-Lysine添加量0.08%、pH值为9、MB浓度为200mg/L时,NFC-g-Lysine对MB的平衡吸附量达到178 mg/g,相比NFC(110 mg/g)提高了61%;NFC-g-Lysine等温吸附过程符合Freundlich模型;动力学数据表明NFC-g-Lysine对MB的吸附满足伪二级动力学方程。     

羧甲基纤维素/聚苯胺复合凝胶球的制备及性能

以金属离子化合物FeCl_3为交联剂和氧化剂,采用物理交联法一步合成羧甲基纤维素/聚苯胺复合导电凝胶球,通过FT-IR、SEM和EDS对复合凝胶的分子结构和微观形貌进行表征;凝胶的失水率和电导率主要由FeCl_3、羧甲基纤维素和苯磺酸钠的浓度控制,当羧甲基纤维素浓度为4.5%、FeCl_3浓度为0.5mol/L和苯磺酸钠浓度为0.4mol/L时,凝胶的失水率为30.2%,具有最佳电导率5.2×10~(-3)S/cm。凝胶对甲基蓝的吸附比较稳定,在不同浓度的甲基蓝溶液中,吸附率保持在30%~50%左右,甲基蓝初始浓度在最大值14mg/L时,吸附量达到最大值17.58mg/g。     

污泥-稻壳生物炭对水中亚甲基蓝的吸附

以给水污泥与稻壳为主要原料，添加适量聚乙烯醇、磷酸和海泡石，通过真空热解方式制备一种可悬浮的颗粒状吸附材料，并将其用于去除模拟印染废水中的亚甲基蓝（MB）。通过批量吸附实验考察吸附剂用量、溶液pH、污染物初始质量浓度以及吸附时间等参数对吸附效果的影响，通过等温吸附模型和动力学模型研究其吸附行为，并利用BET、XRD、SEM-EDS以及FTIR探索吸附机理。结果表明，在MB初始质量浓度为61 mg/L、颗粒吸附材料用量为8 g/L、pH为8、吸附时间为90 min、吸附温度为25℃的条件下，溶液中的MB达到最大去除率81.66%。等温吸附曲线和吸附动力学结果表明，该吸附过程与Langmuir等温吸附模型、准二级动力学模型的拟合度较好，表明吸附材料对MB的吸附过程主要为单分子层的化学吸附，理论最大吸附量为66.67 mg/g。微观分析表明，吸附材料主要是通过中孔及纤维吸附、羟基取代和π-π相互作用吸附废水中的MB。     

海藻酸钠基材料的制备及对金属离子的吸附

采用海藻酸钠作为原材料,使用丙烯酰胺进行化学改性制备海藻酸钠交联丙烯酰胺材料(SA-PAM)。使用红外分析、扫描电镜-能谱仪、元素分布特征和热重分析进行表征,并使用SA-PAM材料对水体中铜和铅离子进行吸附。结果表明,当溶液pH对铜和铅离子分别为5和5.5、初始铜和铅离子浓度为100 mg/L和300 mg/L和吸附时间为2 h时,SA-PAM对铜和铅离子的最大吸附量分别为58.84 mg/L和230.706 mg/L。SA-PAM吸附剂的吸附过程符合拟二阶动力学方程和Langmuir等温线模型,表明其吸附以单层化学吸附为主。此外,经过五次循环实验,SA-PAM材料仍能保持较好的吸附能力。     

一种球形木质素吸附剂吸附L-天门冬氨酸的性能研究

以硫酸盐木质素为原料,利用反相悬浮技术制备出球形木质素吸附剂。利用球形木质素吸附剂吸附L-天门冬氨酸,并进行吸附条件的优选实验。结果表明,吸附效果取决于吸附时间、吸附质初始质量浓度、吸附质溶液pH值以及盐浓度等。当吸附时间150 min、吸附质初始质量浓度2000 mg/L、吸附质溶液pH值为3时,球形木质素吸附剂的平衡吸附容量可达518 mg/g,最大饱和吸附量达到625 mg/g。此外,无机盐氯化铵对球形木质素吸附剂吸附率的影响大于氯化钠,而且随着盐浓度的增大,吸附率从85.6%降至21.4%。同时进行了解吸再生和对比实验,发现用0.6 mol/L的氨水解吸时,解吸率可达99.3%,且再生后的木质素吸附剂仍具有很好的吸附性能。     

OS-PVA/P(DMC-AM)双网络水凝胶的制备及其吸附性能研究

本研究在氧化淀粉（OS）和聚乙烯醇（PVA）的存在下,通过甲基丙烯酰氧基乙基三甲基氯化铵（DMC）和丙烯酰胺（AM）间简单的自由基聚合,制备了力学性能良好、可重复循环使用的双网络水凝胶。当OS溶液质量分数9%时,制备的水凝胶性能最佳,其压缩模量可达2.01 MPa,润胀度仅11.16 g/g,在25℃下对pH值8,浓度200 mg/L的亚甲基蓝溶液吸附480 min时吸附量最高,达602.6 mg/g。经过5次吸附-脱附过程后,双网络水凝胶对亚甲基蓝的去除率仍高达94.8%,脱附率74.2%。     

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.     

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.     

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.     

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.