瓜尔胶及其衍生物在造纸法再造烟叶中的应用

本文在分析了造纸法再造烟叶浆料的纤维形态及筛分情况的基础上,研究了瓜尔胶及其衍生物对造纸法再造烟叶浆料的助留助滤性能。结果表明瓜尔胶及其衍生物能够改善浆料的助留助滤性能,实验室自制的阳离子羟丙基瓜尔胶的助留助滤性能较好,当其用量为0.08%时,浆料中总细小组分首程留着率较未添加时提高了44.0%,浆料的打浆度由43°SR下降到21°SR。同时研究了瓜尔胶及其衍生物对造纸法再造烟叶基片物理性能的影响,结果表明在添加量适当时,阳离子羟丙基瓜尔胶和阳离子瓜尔胶-丙烯酰胺接枝共聚物能够在不影响基片匀度的情况下提高基片的抗张强度和松厚度。     

阳离子羟丙基瓜尔胶在二次纤维的应用研究

自制阳离子羟丙基瓜尔胶(CHPG)应用于废新闻纸浆抄造过程,探讨了CHPG用量、纸浆体系pH值及电导率等对单程留着率的影响,并进一步研究了CHPG/硼砂的二元体系对细小组分的留着增效作用。实验表明,当CHPG用量为0.4%(对绝干浆),pH7.5～8.8,电导率2000μs/cm时,可以将86%的细小组分留着在网部,打浆度自48°SR下降到31°SR;相同用量的CHPG,当添加硼砂〔m(CHPG):m(硼砂)=3∶1〕可以继续提高FPR10%～20%,但打浆度不再下降,其抗无机盐和剪切速度的能力得到改善。     

（CSPI-PEI）-膨润土微粒助留助滤体系在废纸造纸中的应用

研究了膨润土用量、剪切力、电导率、p H值对阳离子大豆分离蛋白-聚乙烯亚胺接枝物(CSPI-PEI)-膨润土微粒助留助滤体系性能的影响。结果表明,膨润土的最佳用量为0.4%左右,(CSPI-PEI)-膨润土微粒体系在中碱性抄纸体系中有良好的助留助滤效果,与CSPI-PEI单元体系相比,细小组分留着率提高了8.0个百分点,浆料打浆度下降了6°SR;(CSPI-PEI)-膨润土微粒体系比CSPI-PEI单元体系具有更好的抗剪切力和抗电导率干扰能力,且使纸张的物理性能稍有提高。     

壳聚糖和阳离子瓜尔胶在造纸法再造烟叶中的应用

分别以阳离子瓜尔胶和自制的壳聚糖为湿部助剂,研究其对再造烟叶浆料Zeta电位、打浆度、动态滤水、单程留着率、再造烟叶基片抗张强度和松厚度的影响。研究表明:与阳离子瓜尔胶相比,壳聚糖对再造烟叶浆料Zeta电位、打浆度、动态滤水和单程留着率的影响更为明显,而且脱乙酰度越高,效果越好;上述助剂的加入均会降低基片的抗张强度并提高松厚度,但不同助剂间的影响较小。通过正交试验对壳聚糖的应用条件进行优化,最佳工艺条件为:壳聚糖的脱乙酰度为90%,添加量为质量分数0.6%(以绝干浆料质量为基准),体系pH为6。     

阳离子壳聚糖在卷烟纸抄造中的应用研究

以壳聚糖(CTS)和2,3-环氧丙基三甲基氯化铵为主要原料制备了水溶性的2-羟丙基三甲基氯化铵壳聚糖(HTCC),研究了HTCC对卷烟纸浆料的Zeta电位、细小组分留着率、灰分留着率、卷烟纸透气度及其抗张强度的影响。结果表明,在取代度为0.5,HTCC用量达到1 mg/g时,细小组分留着率达到85.2%,灰分留着率达到22.7%。同时,对HTCC和瓜尔胶助留效果进行了比较,在HTCC加入量为0.5 mg/g时,灰分留着率达到28.5%,留着效果好于瓜尔胶(17.3%)。     

壳聚糖与瓜尔胶在甘草渣薄片纸基中的应用研究

选用阳离子瓜尔胶和三种不同分子量的壳聚糖作为甘草渣薄片助剂,研究了加入不同量的不同助剂对甘草渣浆料的动态滤水、单程留着率、Zeta电位和打浆度的影响。结果表明:壳聚糖对甘草渣浆料的助留助滤效果强于阳离子瓜尔胶,高脱乙酰度的壳聚糖优化效果更好;当2#普通壳聚糖的加入量为0.4%时,浆料系统的助留助滤的综合效果最佳。加入不同量的4种助剂后抄造甘草渣基片,分析基片物理性能的变化,结果表明:加入助剂会提高基片的松厚度并降低抗张强度。当2#壳聚糖的加入量为0.4%时,薄片综合性能较好,松厚度达到4.74cm3/g,其燃烧速率适宜,对薄片性能的负面影响较小。     

微粒助留助滤体系对烟草薄片浆料助留助滤性能的影响

在造纸法烟草薄片的生产中,利用食品安全级的阳离子壳聚糖和瓜尔胶与膨润土和胶体二氧化硅组成二元微粒助留助滤体系,研究其对烟草浆料助留助滤性能的影响。研究结果表明：使用壳聚糖／膨润土或瓜尔胶／膨润土组成的二元微粒助留助滤体系能明显改善烟草浆料的留着率和滤水性能。壳聚糖（用量为0．1％）与膨润土（用量为0．4％）所组成的二元微粒体系与只添加0．1％的壳聚糖相比,烟草浆料单程留着率和填料留着率分别提高14％和12％,20s内滤水量提高200g。     

三元助留体系对高得率浆助留助滤性能的研究

研究了阳离子瓜尔胶单元、二元、三元助留助滤体系在高得率浆抄造上的应用.并考察了PAC用量、电导率、pH值对PAC-阳离子瓜尔胶一膨润土三元体系对高得率浆助留助滤性能的影响.结果表明,三元体系较单元和二元体系对高得率浆具有更好的助留助滤作用,当PAC用量为1%,阳离子瓜尔胶用量为O.3%,膨润土加入量1%时,三元体系对高得率浆的留着率达到93.6%、滤水时间可达15s.     

四种助剂对造纸法再造烟叶浆料助留助滤的影响

造纸法再造烟叶的品质和产品得率与浆料的Zeta电位、导电率、动态滤水性能和单程留着率密切相关,本研究设计了5个打浆度梯度,并选择了CMC、壳聚糖、瓜尔胶和阳离子瓜尔胶四种助剂,分别对再造烟叶浆料的上述指标进行考察。结果表明,随着浆料打浆度提高,其Zeta电位逐渐降低,电导率逐渐升高;当CMC和壳聚糖加入浆料后,能降低浆料的Zeta电位和动态滤水性能;当瓜尔胶加入浆料后,其Zeta电位逐渐升高,电导率逐渐降低,滤水性能基本无变化,当阳离子瓜尔胶加入浆料后,其Zeta电位、电导率和动态滤水性能逐渐升高,CMC对浆料的单程留着率的影响较大,壳聚糖、瓜尔胶和阳离子瓜尔胶对浆料的单程留着率影响较小。综合比较对Zeta电位、导电率、动态滤水性能和单程留着率的影响,CMC的效果比壳聚糖、瓜尔胶和阳离子瓜尔胶更好,在实际应用中可优选CMC。     

两性瓜尔胶的制备及其助留助滤性能的研究

以氯乙酸钠为阴离子化试剂,对阳离子瓜尔胶进行改性,采用半干法制备具有不同羧基含量的两性瓜尔胶。通过浆内添加研究了两性瓜尔胶的羧基含量和用量对卷烟纸助留助滤性能的影响,同时与阳离子瓜尔胶进行了效果对比,并考察了两性瓜尔胶和非离子瓜尔胶在卷烟纸中的复配使用效果。通过正交实验获得了制备两性瓜尔胶的优化工艺：碱化用碱量0．50％,碱化时间60min,阴离子化试剂与原料摩尔比为0．5：1,阴离子化时间3h,反应温度80℃。两性瓜尔胶用作助留助滤剂具有更好的效果,羧基含量为2％左右时,在用量为0．06％时效果较佳,纸浆打浆度下降15．5％,纸料总留着率和灰分分别提高了14．0％和151．9％;与非离子瓜尔胶按2：8复配使用时还可有效提高纸张强度。     

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.     

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.     

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.     

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.     

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.     

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.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

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.