交联型聚乙烯醇表面施胶剂的制备及作用机理

采用γ-缩水甘油醚氧丙基三甲氧基硅烷（KH560）对聚乙烯醇（PVA1799）进行接枝改性,制备了交联型聚乙烯醇表面施胶剂（PVA-KH560）;通过傅里叶变换红外光谱、氢核磁共振谱及稳定性测试等对PVA-KH560结构及稳定性进行分析,并对PVA-KH560与PVA1799复配施胶前后纸张的物理性能进行了分析。结果表明,KH560中的环氧基团在PVA-KH560中消失,含硅支链成功接枝到PVA1799长链中;当m（PVA1799）∶m（KH560）=9∶1.5时,PVA-KH560稳定且粒径最小（122.2 nm）,分散性指数为0.291;和原纸相比,复配施胶纸张耐折度、抗张指数、挺度、撕裂指数、耐破指数分别提高了436.0%、60.1%、116.4%、89.9%、80.5%,接触角增大了57.7%,综合性能优于单独使用PVA1799的施胶纸。     

封闭型水性聚氨酯合成及在纸张表面施胶中的应用

采用一步聚合法,以聚乙二醇350单甲醚（mPEG350）、丁二醇（BDO）、二羟甲基丙酸（DMPA）、异佛尔酮二异氰酸酯（IPDI）为原料进行聚合,得到一种封闭型的水性聚氨酯（BWPU）。将质量分数1%的BWPU与质量分数4%的PVA复配成施胶液（SSA）,用于纸张表面施胶。结果表明,当DMPA添加量为10%、n（mPEG350）∶n（BDO）=1∶0.2、n（—NCO）∶n（—OH）（R值）为1.8,甲乙酮肟（MEKO）添加量为21.3%时,制备得到的BWPU性能最佳,其粒径为291.0 nm,分散稳定性指数（TSI）为1.33。施胶后的纸张撕裂指数为11.9 mN·m²/g,挺度为95.8 mN,抗张指数为82.6 N·m/g,耐折度为3394次,接触角为79.69°,施胶度为28.14°;与原纸相比,各项指标分别提高了76.8%、43.4%、7.8%、71.2%、26.3%,1307.0%。与市售施胶剂施胶后纸张相比,各项指标分别提高了20.9%、8.1%、15.9%、15.2%、10.3%、24.0%。     

非水介质中羧基酯化聚乙烯醇的合成及其在表面施胶中的增强应用

以N-甲基-2-吡咯烷酮（NMP）为溶剂,四丁基溴化铵为催化剂,通过马来酸酐（MAH）对低醇解度的聚乙烯醇（PVA0588）进行改性,得到羧基酯化聚乙烯醇（NWMPA）;通过FT-IR、1H-NMR等手段对NWMPA的结构进行表征;分析了PVA0588与MAH质量比对NWMPA羧基含量及其分散液稳定性等性能的影响;最后探讨了PVA1799与NWMPA复配的用量对纸张物理性能的影响。结果表明,当m(PVA0588)∶m(MAH)=2∶1时,NWMPA-3分散液相对稳定,平均粒径为368 nm、分散性指数为0.418、稳定指数为3.802,碘值和羧基含量分别达到28.55 g/（100 g）和49.65 mmol/L;与原纸相比,3.0 wt%NWMPA-3与4.0 wt%PVA1799复配施胶后纸张的施胶度、干抗张指数、湿抗张指数、耐折度分别提高了1246.5%、33.6%、50.6%、243.8%;与市售施胶剂相比,PVA1799/NWMPA-3复配施胶剂的储存期更长,对纸张油墨附着力等级可达到合格等级4B。     

聚乙烯亚胺改性KH560作为纸基材料表面施胶增强剂的研究

利用聚乙烯亚胺（PEI）与γ-缩水甘油醚丙基三甲氧基硅烷（KH560）反应制得表面施胶增强剂PEI-KH560,并对其施胶性能和增强性能进行了考察。结果表明,PEI-KH560能够显著改善手抄片的物理性能和疏水性能。与空白样相比,当PEI-KH560用量为1.35%时,手抄片的干、湿抗张指数分别提高了33.9%和61.8%,表面接触角由53.4°提高至69.8°,Cobb60值降低了24.3%,手抄片表面由高度亲水性转变为具有一定的疏水性。PEI-KH560增强了手抄片纤维间的结合强度,改善了手抄片的强度性能,同时赋予手抄片疏水性能。     

淀粉-无机盐体系表面施胶对瓦楞原纸应用性能的影响

主要研究了淀粉-无机盐表面施胶体系对瓦楞原纸应用性能的影响。用硝酸镁、氯化镁、硫酸镁取代部分玉米淀粉对瓦楞原纸进行表面施胶,探讨无机盐的添加对瓦楞原纸物理强度及其他性能的影响。结果表明,当淀粉与无机盐的用量比（质量比）为8∶2、施胶量为6 g/m²时,相对于瓦楞原纸,硝酸镁、氯化镁、硫酸镁替代部分淀粉施胶后纸样的横向环压指数分别增长了76.3%、80.0%、82.5%,纵向环压指数分别增长了74.7%、72.6%、80.9%,耐破指数分别增长了13.1%、14.3%、15.6%。在施胶液中添加接枝淀粉型表面施胶剂,纸张的Cobb值从140 g/m²降至30 g/m²左右,满足成纸的防潮性能要求。     

水性封闭型异氰酸酯交联剂的制备及其在表面施胶中的应用

以异佛尔酮二异氰酸酯（IPDI）和1,4-丁二醇（BDO）为原料,2,2-二羟甲基丙酸（DMPA）为扩链剂,N-甲基-2-吡咯烷酮（NMP）为溶剂,采用一步法制备聚氨酯预聚体,随后采用丁酮肟（MEKO）对预聚体进行封端反应,经有机碱中和并加水乳化,制得水性封闭型异氰酸酯交联剂（WBIC）。将制得的WBIC与聚乙烯醇（PVA1799）进行复配,在一定温度下对纸张进行施胶并在约110℃进行解封反应。通过傅里叶变换红外光谱（FI-TR）、热重分析（TGA）及乳液稳定性等测试,对样品结构及稳定性进行分析并对施胶后纸张进行物理性能测试。结果表明,当R值（—NCO/—OH）为1.8且以MEKO封端时,制得的乳液稳定且粒径最小,为85.14 nm,聚合物分散系数（PDI）为0.171。施胶后纸张物理性能大幅提高,与原纸相比,耐折度、抗张指数、挺度、撕裂指数和耐破指数分别提高了57.6%、29.1%、165.4%、31.0%和59.0%;施胶后纸张接触角为96°。     

Cd2+-PVA/PA6金属配合纳米纤维的制备及反应动力学分析

 利用静电纺丝技术得到PVA/PA6复合纳米纤维,并将其与镉离子（Cd2+）溶液反应,制备Cd2+-PVA/PA6金属配合纳米纤维。采用原子吸收光谱（AAS）测定金属离子浓度,用傅里叶红外光谱(FTIR)对PVA/PA6复合纳米纤维和Cd2+-PVA/PA6金属配合纳米纤维的相应吸收峰进行分析,用扫描电子显微镜（SEM）对其形貌进行表征。结果表明,PVA/PA6纳米纤维具有优异的金属离子配合性能和良好的形态稳定性。同时研究了金属离子吸附过程及动力学参数,得出吸附常数K_l=0.0257 L/mmol、饱和离子配合量Q_m=4.4643 mmol/g,相关系数R²=0.997,该反应过程符合兰格缪尔吸附模型。     

硅酸钠表面施胶改善纸张防水性能的机理探讨

分别利用硅酸钠、硅酸钠与淀粉复配进行纸张表面施胶，表面施胶体系中有机硅油用量控制为3%（相对于硅酸钠绝干质量）；探讨了施胶量和施胶体系对纸张孔隙率、纸张平均孔径、表面平滑度、Cobb₃₀值和表面接触角的影响；依据毛细管现象公式，探讨及分析了表面施胶纸张的防水机理；利用扫描电镜（SEM）观察分析了表面施胶纸张的表面形貌。结果表明，硅酸钠-淀粉复配体系中，淀粉最佳用量为33%；随着表面施胶体系施胶量的增加，表面施胶纸张的孔隙率和平均孔径均下降；经硅酸钠和硅酸钠-淀粉复配表面施胶后，纸张的表面接触角较原纸大幅提高且硅酸钠-淀粉复配体系对纸张抗水性的改善效果优于硅酸钠。此外，研究还发现，纸张平均孔径的降低、表面接触角的增加及胶层在纸张表面的覆盖是硅酸盐及其复配体系表面施胶纸张产生抗水性的主要原因。     

有机硅烷改性自交联聚丙烯酸酯微乳液的制备与纸张表面施胶性能

采用无皂乳液聚合,以甲基丙烯酸甲酯(MMA),丙烯酸丁酯(BA),丙烯酸(AA),丙烯酸羟丙酯(HPA)等为原料,γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)为硅烷交联剂,制备了一种稳定的阴离子型聚丙烯酸酯微乳液,其可作为表面施胶剂用于纸张表面增强处理。讨论了KH570用量对乳液及施胶纸张性能的影响。结果表明,有机硅氧烷单体成功的键接到丙烯酸酯聚合物上,且当ω(KH570)=1.78%(质量分数,下同)时,乳液综合性能佳且其施胶效果好,乳液粒径低至45.80nm。表面施胶后的纸张强度有明显提升,干湿强度分别提高26.5%、27.1%,耐折度提高332.4%,施胶度提高49.85%,纸张水滴接触角可由35.2°增加至59.1°。     

Ca2+交联羧基化麦草秸秆化机浆的制备及性能研究

本研究采用TEMPO氧化体系,转化麦草秸秆化机浆（SP）纤维素C6位上的羟基为羧基,制备羧基化麦草秸秆化机浆（CSP）;对CSP进行Ca²⁺交联,制备Ca²⁺交联羧基化麦草秸秆化机浆（CSP@Ca²⁺）,探究其纸浆的物理强度性能。基于FT-IR、XPS等手段可以明显检测CSP 纤维的羰基/羧基官能团：羧基化1 h麦草秸秆化机浆纤维（CSP1）的羧酸含量为0.27 mmol/g,其Zeta电位从SP的-21.7 mV变化为-29.2 mV,这为Ca²⁺的交联提供作用位点。纸张物理强度结果表明,CSP1@Ca²⁺0.5的抗张指数、耐破指数和撕裂指数分别较SP提高154.4%、170.8%和12.9%。最终,CSP1@Ca²⁺0.5与SP配抄纸张（配抄比例为50∶50）的抗张指数、耐破指数和撕裂指数分别达27.1 N·m/g、2.28 kPa·m²/g和3.68 mN·m²/g,较SP分别提高83.4%、115.1%和8.3%。     

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.     

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.     

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.     

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.     

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.