酚酸物质抗氧化性及溶剂化效应的理论计算

运用M06-2X泛函对12种酚酸物质进行理论计算,以抗氧化性指标键解离焓（bond dissociation enthalpy,BDE）、电离势（ionizationpotential,IP）、质子解离焓（protondissociationenthalpy,PDE）、质子亲和力（proton affinity,PA）和电子转移焓（electron transfer enthalpy,ETE）为理论指标,对酚酸在气相及溶剂中进行分析,阐释其抗氧化性及溶剂化效应。结果表明：以BDE为标准,气相中龙胆酸（C5）的BDE最低;在苯中抗氧化性最好的是咖啡酸（C6）,丙酮中为龙胆酸（C5）,乙醇和水中为3,4-二羟基苄醇（C2）;以IP为标准,在气相及4种溶剂中抗氧化性最好的均为白藜芦醇;就抗氧化机制而言,酚酸物质主要发生氢原子转移机制。通过5种表征抗氧化性指标IP、BDE、PDE、PA和ETE分析得出,无论是酚酸脱氢阴离子还是阳离子,生成脱氢自由基的能力与受到溶剂极性大小的影响一致。总体来说,弱极性溶剂丙酮中的抗氧化能力相对最强,强极性溶剂水和乙醇中抗氧化能力稍弱于丙酮,在非极性溶剂中,酚酸的...     

咖啡果壳微晶纤维素制备及其吸附性能研究

目的：利用咖啡果壳制备高吸附能力微晶纤维素。方法：用酸解法制备咖啡果壳微晶纤维素,考察酸解时间、酸解温度、盐酸质量分数和料液比对微晶纤维素得率和吸附能力的影响。结果：咖啡果壳微晶纤维素的最佳制备工艺为酸解时间95 min,盐酸质量分数16%,料液比（m_{咖啡果壳纤维素}∶V_酸）1∶22 （g/mL）,酸解温度60 ℃,该工艺条件下咖啡果壳微晶纤维素得率为80.08%,对香精的吸附能力为0.89 g/g。结论：料液比对咖啡果壳微晶纤维素得率影响最大,酸解温度对其吸附能力影响最大,优化工艺得到的咖啡果壳微晶纤维素得率高,吸附能力强。     

纤维素结合域的引入对角质酶在纤维素类纤维上吸附性能的影响

为了研究纤维素结合域（Cellulose-binding Domain,CBD）的引入对角质酶在纤维素类纤维上吸附能力的影响,本文选用漂白棉织物、粘胶纤维、醋酯纤维以及纯棉针织坯布这四种材质,对角质酶与CBD-角质酶进行吸附对比试验。研究表明：CBD结构的引入,可提高角质酶在纤维素纤维上的吸附量。但是当纤维素葡萄糖残基上羟基被部分酯化后,CBD结构的引入对吸附量造成的影响开始减弱,而当纤维素纤维表面被疏水性杂质覆盖时,CBD-角质酶对纤维素纤维的吸附能力反而降低。     

茶多糖脱色的研究

研究了7种离子交换树脂和吸附树脂对茶多糖溶液中的色素脱除的影响,筛选出3种树脂非极性大孔吸附树脂DA201C、大孔弱碱性的阴离子交换树脂D301G和D315,通过单因素试验和正交试验对脱色条件进行优化。研究发现,采用树脂D315,在pH=45,T=55℃下,茶多糖溶液的脱色率可达到8982%,多糖保留率为6486%,蛋白质去除率9395%。茶叶中的色素可能主要以带负电荷的非极性小分子色素为主。     

旧报纸碳基气凝胶的制备及其吸附性能的研究

将富含纤维素的旧报纸先进行润胀、打浆,然后冷冻干燥,得到旧报纸气凝胶（WNA）,利用高温热分解的方式处理WNA制得旧报纸碳基气凝胶（CA）。采用傅里叶变换红外光谱（FT-IR）、扫描电子显微镜（SEM）、X射线衍射仪（XRD）对CA的性能进行表征。结果表明,CA的密度（0.0348 g/cm³）较低,动态接触角为129.8°,表明CA的疏水性能优异。FT-IR结果表明,与WNA相比,CA中羟基、烷基及糖苷键等官能团含量减少。SEM分析表明,CA的纤维宽度在8～10 μm范围内,其具有连续纳米多孔三维网络结构。XRD分析表明,纤维素的结晶区受到破坏,导致无定形碳的形成。CA能高效、快速地吸附有机溶剂和石油化工产品,吸附量可达自身质量的21～37倍。利用燃烧的方法可将吸附的物质从CA中分离出来并对CA进行回收。经过6个吸附/燃烧循环过程,CA对甲醇和硅油的吸附能力分别是原吸附能力的83.9%和86.4%,表明CA可实现多次循环利用。     

掺杂改性纤维素复合气凝胶的制备及吸附性能

为提高纤维素材料在废水处理中的吸附性能，利用蒙脱土（MMT）和壳聚糖（CS）对再生纤维素（RC）掺杂改性，制备了多元复合气凝胶。对气凝胶结构进行了表征，评价了气凝胶对重金属离子的吸附性能。结果表明：CS的加入增强了与纤维素分子的作用力，能构建具有均匀微孔结构的复合气凝胶，提高了气凝胶的机械性能及其孔隙率，降低了密度。相对于纯RC气凝胶，复合气凝胶对重金属离子的吸附性能明显提升，其中RC-MMT-CS复合气凝胶对Pb~(2+)、Cd~(2+)、Co~(2+)和Cu~(2+)的最大吸附量分别达到220.9、153.1、134.5、65.5 mg/g，是RC-MMT复合气凝胶的1.4、1.5、1.6、2.1倍，RC气凝胶的12.3、10.0、10.6、6.7倍。同时，RC-MMT-CS复合气凝胶具有良好的再生利用性能，5次循环后对4种重金属离子的吸附能力仍均能保持在75%以上。     

白果壳纤维素对不同种类多酚的吸附行为及其动力学研究

将天然抗氧化剂酚类与白果壳纳米纤维素结合,探究纤维素对不同种类多酚的吸附行为及动力学的影响,并制备一种具有抗氧化功能的纤维素/酚复合颗粒。该研究使用氮气吸附仪对白果壳纳米纤维素进行孔性能表征,研究了其对儿茶素、茶多酚、表没食子儿茶素没食子酸酯、没食子酸和阿魏酸的吸附行为,采用一级和二级动力学模型对吸附曲线进行拟合,以Weber-Morris颗粒间扩散模型描述吸附过程,用X射线光电子能谱分析纤维素吸附多酚前后的表面化学结构变化,以DPPH自由基、ABTS阳离子自由基清除能力为标准,考察复合颗粒的抗氧化能力。实验结果表明,白果壳纳米纤维素的比表面积为246.71 m²/g,孔体积为0.35 cm³/g,选取的5种酚类物质均可以自发吸附到纤维素上,展示出快速—慢速—平衡的吸附过程。其中白果壳纤维素对儿茶素的吸附能力最大,可达3.7 mg/g纤维素。以儿茶素为例,进一步探究离子强度、pH、温度3种环境因素对吸附情况的影响,中性pH和高离子强度有利于纤维素对酚的吸附,而温度变化对吸附作用没有显著影响。纤维素吸附儿茶素后,其表面的化学结构发生变化。吸附儿...     

甘薯渣纤维素粒度对去势大鼠血脂降低效果的影响

目的：探讨纤维素粒度对其降血脂效果的影响。方法：选用40 只雌性SD大鼠随机分组为5 组,其中1 组大鼠进行伪切除手术作对照,另外4 组大鼠做双侧卵巢切除手术,基础饲料喂养恢复1周后,分为空白组、普通纤维素组、超微纤维素组和纳米纤维素组,实验期28 d后解剖,测定血浆和肝脏中脂质指标。体外检测3 种粒度纤维素的消化性和吸附性能。结果：3 种粒度纤维素对油脂、胆固醇和胆酸钠都有较强吸附,对油脂和胆酸钠的吸附能力随纤维素粒度减少而增加。3 种纤维素均降低双侧卵巢切除大鼠血浆总胆固醇、甘油三酯、低密度脂蛋白胆固醇浓度和动脉硬化指数值以及肝脏中总脂肪、甘油三酯的浓度。纤维素粒度与双侧卵巢切除大鼠血浆总胆固醇、甘油三酯、低密度脂蛋白胆固醇浓度呈正相关性。结论：减小纤维素粒度有利于增加纤维素对油脂和胆酸盐的吸附能力,提高纤维素降低双侧卵巢切除大鼠血脂的效果。     

银杏酚酸的分离鉴定及其抗菌活性研究

本文以银杏外种皮为原料,研究了吸附树脂分离纯化银杏酚酸的方法和银杏酚酸的抗菌活性,并对其结构进行了鉴定。结果表明:非极性树脂D4020和弱极性树脂AB-8对银杏酚酸具有较好的吸附能力,银杏酚酸粗提液经两种树脂吸附,不同浓度乙醇梯度洗脱后,产物纯度可达90%,得率为0.91%,利用树脂精制银杏酚酸成本低、效率高,是一种有效的分离方法;通过LC/DAD/MS分析表明,银杏酚酸由五种异构体(C13:0,C15:1,C17:2,C15:0,C17:1)组成,其中C15:1含量最高,其次是C17:1;银杏酚酸主要抑制革兰氏阳性菌,对蜡状芽孢杆菌、枯草芽孢杆菌和金黄色葡萄球菌有很好的抑制作用,而对大肠杆菌等革兰氏阴性菌无抑制作用,酚酸的烷基侧链在抑菌中起了重要作用。     

聚离子液体改性废报纸基纤维素气凝胶及其染料吸附性能研究

采用超声脱墨技术纯化废报纸（WNP）,将得到的脱墨纤维素纤维在碱溶剂体系中溶解并交联再生制备纤维素气凝胶（WNCA）,最后通过化学接枝法制备了聚（1-乙烯基-3-丁基咪唑溴盐）聚合物刷修饰的纤维素气凝胶吸附剂（WNCA-g-PBVIMBr）;研究了WNCA-g-PBVIMBr的化学结构与物理形貌,探索了其对染料酸性橙II（AO II）的吸附性能与吸附机理。结果表明,WNCA表面均匀接枝了平均分子质量为3780 g/mol的PBVIMBr聚合物刷,其对AO II的最大吸附容量为351 mg/g,吸附过程符合准二级动力学模型和Langmuir等温吸附模型,且化学吸附起主导作用。     

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