交联壳聚糖树脂吸附阿司匹林的动力学和热力学研究

以壳聚糖为原料,戊二醛为交联剂,通过水相均匀交联法制备出交联壳聚糖树脂,用红外光谱对其结构进行表征,并利用交联壳聚糖树脂对乙醇溶液中阿司匹林进行了吸附动力学和热力学研究。结果表明,在50 m L质量浓度为200 mg·L~(-1)的阿司匹林溶液中,交联壳聚糖投加量0.3 g、p H4.0、吸附温度293 K、搅拌速率150 r/min时,吸附动力学符合准二级动力学方程,表观吸附活化能为25.96 k J·mol~(-1),等温吸附更符合Freundlich方程。在293~333 K、阿司匹林吸附量为10~20 mg·g~(-1)条件下,吸附焓、自由能变及吸附熵变分别为-19.81~-13.80 k J·mol~(-1)、-1.83~-1.54 k J·mol~(-1)和-61.36~-36.81 J·mol~(-1)·K~(-1)。吸附过程为自发的不可逆放热熵减过程,且低温有利于吸附。为交联壳聚糖树脂吸附阿司匹林提供了理论基础。     

珠状壳聚糖树脂对绿茶中茶多酚的吸附研究

本实验制备了珠状壳聚糖树脂,通过TG-DSC 对其热稳定性进行了表征,研究了珠状壳聚糖树脂对绿茶中茶多酚的吸附分离性能,探讨了其吸附条件,并就珠状壳聚糖树脂对茶多酚的吸附动力学进行了讨论。结果表明,珠状壳聚糖树脂在温度小于172℃条件下具有较好的热稳定性;珠状壳聚糖树脂对茶多酚较佳的吸附条件为：珠状壳聚糖湿树脂4.0g(干重0.22g)/ 茶多酚含量为1.573mg/ml 的25ml 茶汤、吸附时间2h、茶汤pH7.06、温度30℃。此条件下提取率可达74.1%,单位吸附量为136.1mg/g;珠状壳聚糖树脂对茶多酚的吸附动力学符合Langmuir 等温吸附公式,单位饱和吸附量为1116mg/g。     

牛血清蛋白磁性壳聚糖微球谷氨酸改性吸附

研究谷氨酸改性磁性壳聚糖微球对于牛血清白蛋白的吸附。采用反相悬浮法制备谷氨酸改性磁性壳聚糖微球(GA-CMNs),利用红外光谱仪检测壳聚糖连接谷氨酸效果、扫描电子显微镜(SEM)观察微球形貌、激光粒度仪检测微球粒径分布;考察不同pH值、NaCl质量分数、BSA质量浓度、吸附时间对谷氨酸改性磁性壳聚糖微球BSA吸附效果的影响,并对吸附行为进行吸附动力学和吸附热力学分析。结果表明:最佳吸附溶液pH值为5,BSA质量浓度、吸附时间与BSA吸附量呈正相关,而NaCl质量分数则相反;谷氨酸改性磁性壳聚糖微球对BSA吸附平衡过程符合动力学准二级方程模型和Langmuir吸附等温线模型,在BSA初始质量浓度为1 mg/mL时有最大平衡吸附值,为83.5 mg/g;经过5次3%NaCl溶液洗脱-吸附操作循环后,洗脱率仍高于90%。谷氨酸改性磁性壳聚糖微球对牛血清蛋白的吸附性能良好。     

β-环糊精/壳聚糖膜的制备及在废水处理中的应用

以PEG-400作改性剂,柠檬酸作交联剂,磷酸氢二钠作催化剂,合成了β-环糊精聚合物;然后将壳聚糖与β-环糊精聚合物通过乙烯基三乙氧基硅烷进行交联,制成具有孔洞的β-环糊精/壳聚糖膜;采用FT-IR、XRD、TG和SEM表征其官能团、结晶度、热失重和膜孔洞的尺寸大小。研究表明,自制的β-环糊精/壳聚糖膜孔洞直径约为5μm,其对酸性染料的吸附更符合Langmuir吸附等温线,可认为是单分子层吸附;吸附动力学研究表明,该吸附符合假二级动力学吸附方程。     

水溶性壳聚糖对结冷胶钙凝胶珠包埋与释放特性的影响

壳聚糖是一种阳离子多糖,可与阴离子多糖结冷胶通过离子交联形成具有包埋生物活性物质的功能载体。探讨了水溶性壳聚糖替代天然壳聚糖制备结冷胶钙凝胶珠的可行性。通过测定包封率(EE)、载量(LC)以及牛血清蛋白(BSA)的累积释放率(RR)等指标,对该载体的包埋和释放性能进行了评价,并运用扫描电子显微镜(SEM)、荧光显微镜等手段对比了水溶性壳聚糖和天然壳聚糖制备的凝胶珠在超微结构上的差异。配方优化结果表明,最佳的配方条件应为:0.5 g/100 mL水溶性壳聚糖,0.10~0.15 mol/L氯化钙,1.00~1.50 g/100 mL结冷胶,0.75g/100 mL牛血清蛋白,凝胶珠对BSA的包封率和载量分别可以达到83.05%和12.77%,并在模拟消化液中有明显的缓释效果。     

聚合氯化铝铁-改性壳聚糖复合吸附Cr~(3+)效果研究

为了丰富壳聚糖骨架上的活性吸附位点,对壳聚糖进行交联改性,并将其和聚合氯化铝铁复合使用来吸附Cr3+。实验以Cr3+的去除率为考察指标,研究了聚合氯化铝铁/交联壳聚糖的质量比、吸附剂投加量、吸附时间、吸附温度、pH等因素对吸附效果的影响,最后通过正交实验优化了吸附工艺,得最佳吸附参数为:聚合氯化铝铁-交联壳聚糖质量比1∶2、投加量7 g、pH=8、吸附时间70 min、吸附温度35℃,此条件下的吸附效果最好,Cr3+的吸附率达96.934%。     

交联壳聚糖对印刷废水中Cr6＋离子吸附性能的研究

对印刷废水中重金属Cr6＋离子的去除,及绿色、高效的废水处理剂的开发研究具有重要意义.本实验以环氧氯丙烷为交联剂,在碱性条件下和壳聚糖反应,制备了交联壳聚糖,通过傅立叶变换红外光谱（FT-IR）对其结构进行表征,并采用静态吸附法,考察了pH值、吸附时间、离子初始浓度、吸附剂用量等因素对Cr6＋离子吸附率的影响,确定了最佳的吸附条件.实验结果表明：在Cr6＋起初浓度≤100mg/L,交联壳聚糖的加入量为0.1g,pH值为3,振荡2h时,吸附剂对Cr6＋离子的吸附容量为9.91mg/g,一次吸附率可以达到99.1％.为了达到国家标准中关于Cr6＋的排放浓度的标准（＜ 0.5mg/L）,又进行二次吸附交联壳聚糖的用量调整实验,结果表明：二次吸附后能很好地将Cr6除去,并达到排放要求.     

壳聚糖/纤维素硫酸酯复合小球的制备及其对BSA吸附性能的研究

以离子液[Emim]Ac为溶剂,采用挤球法制备壳聚糖/纤维素硫酸酯(CHT-CS)复合小球,探索制备条件,并用FT-IR、SEM和XRD对其进行表征。将复合小球用于吸附牛血清蛋白(BSA),考察影响CHT-CS吸附BSA的因素。结果表明:制备复合小球的最佳条件是纤维素酸酯的取代度为0.58,复合原料液的浓度为5%,壳聚糖:纤维素硫酸酯为1:1;纤维素硫酸酯和壳聚糖在制备过程中发生了复杂的相互作用,形成了结构稳定,表面和内部均存在大量沟壑和孔洞的小球;所制备的复合小球对BSA的最大平衡吸附量达到157 mg/g,高于其他壳聚糖复合材料;当BSA初始浓度1 mg/m L、溶液p H为5左右,小球对BSA的吸附量最大;一定范围内增加小球投加量在可增大BSA吸附量。本研究结果为分离纯化BSA和CHT-CS复合小球固定化酶等方面的应用提供了参考。     

磁性壳聚糖改性对高岭土吸附蔗糖溶液中咖啡酸性能的影响

目的:研究磁性壳聚糖改性高岭土对模拟蔗汁中咖啡酸的吸附特性。方法:通过共沉淀法将壳聚糖、纳米四氧化三铁与高岭土结合制备成磁性壳聚糖改性高岭土,通过FT-IR、VSM和SEM表征高岭土改性前后表面结构和基团变化,采用吸附试验研究磁性壳聚糖改性高岭土对咖啡酸的吸附特性。结果:改性后壳聚糖和纳米Fe₃O₄成功地负载到了高岭土上并提升了其对咖啡酸的吸附性能,磁性壳聚糖改性高岭土的等电点为4.54,酸性条件有利于咖啡酸的去除,并在240 min时达到吸附平衡。磁性壳聚糖改性高岭土对咖啡酸的吸附过程更符合准二级动力学和Langmuir等温线吸附模型,其吸附过程主要为化学吸附和单分子层吸附,热力学研究表明吸附过程为自发吸热过程。结论:磁性壳聚糖改性高岭土对蔗汁中咖啡酸具有较强吸附性能,可作为糖用澄清剂用于蔗汁中咖啡酸的吸附处理。     

PVPP对啤酒中多酚类物质和蛋白质的吸附作用比较

为了比较PVPP对啤酒中多酚类物质和蛋白质的吸附作用,以牛血清蛋白为例,采用PVPP分别处理原啤酒、牛血清蛋白(BSA)溶液以及BSA原啤酒混合溶液。实验发现,在相同条件下,尽管PVPP对牛血清蛋白具有较强的吸附作用,但对啤酒中多酚类物质的吸附作用更强;而在BSA原啤酒混合溶液中,多酚类物质被吸附量远远大于牛血清蛋白。结果表明,多酚类物质通过竞争吸附占据PVPP的吸附活性点。     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the