棉秆硫酸盐浆打浆及配抄性能的研究

采用PFI磨对棉秆全秆漂白硫酸盐浆进行打浆,分析了纤维长度和纸张强度指标随打浆度的变化。结果表明,打浆初期棉浆的纤维长度下降很快,打浆度超过50°SR后纤维长度下降趋缓。打浆度对棉浆耐破指数和裂断长的影响相近,在60°SR左右耐破指数和裂断长均达到最大值。而耐折度在接近50°SR时达到最大值。打浆度为40°SR时,撕裂指数开始明显降低,耐折度和耐破指数随打浆浓度上升最快,撕裂指数在低浓范围随打浆浓度上升而明显增大。配抄实验表明,棉浆配比20%以下时配抄防水铜版纸是可行的。     

打浆对棉纤维性能指标的影响

为了研究打浆对棉纤维性能的影响,采用Valley打浆机和PFI磨两种打浆设备对棉浆打浆进行探讨,结果表明:打浆对棉浆的保水值以及纤维形态有很大影响。结合两种设备通过正交实验进行精浆工艺条件的优化,优化出的工艺条件为:初始打浆度20°SR,PFI磨磨浆间隙0.5mm,浆浓15%,磨浆转数38000转,在此条件下浆料保水值104.9%,纤维长度1.065mm,其成纸的抗张指数为54.50N·m·g-1,撕裂指数为19.30mN·m2·g-1,耐折度为146次。     

纤维打浆性能对成纸聚氨酯化改性的影响

采用Valley打浆机和PFI磨对棉浆打浆,浆料成纸后用异佛尔酮二异氰酸酯(IPDI)进行聚氨酯化改性处理.结果表明,IPDI对纸张改性后,使得纸张表面成膜,增强了纤维之问的连接,纸张强度得到提高,尤其是湿强度.当保水值达到最高125.8%时,与原纸相比,改性纸的耐折度、裂断长分别增加14.7倍、1.3倍.湿强度为45.3%,撕裂指数、透气度、不透明度各下降55.9%、19.2%、68.8%.     

棉浆打浆与纤维性能的关系

在不同工艺条件对商品棉浆进行打浆,研究纤维性能的变化,为棉浆的打浆提供理论指导.首先采用PFI磨进行商品棉浆的打浆,研究浆料的性能.然后结合Valley机和PFI磨两者打浆的优点进行棉浆的打浆,先将棉浆在Valley机中疏解并适当打浆,然后再用PFI磨精磨.并做正交试验进行精浆工艺条件的优化.为做对比试验,参照商品棉浆的打浆,也对自制棉浆进行打浆研究.     

不同打浆设备对二次细小纤维产生及质量的影响

利用Valley打浆机、PFI磨和HCR（高浓盘磨）对漂白硫酸盐针叶木浆料进行处理,制备、搜集二次细小纤维;观察其形态,测定黏度、比沉降容积、表面电荷等参数。结果表明：Valley细小纤维以片状组分为主,HCR细小纤维中纤丝状组分与薄片状组分含量相当,PFI细小纤维绝大部分是纤丝状组分,中高浓打浆有利于产生纤丝状细小纤维。添加细小纤维,可提高纸张紧度、平滑度、不透明度,但抗张指数、撕裂指数、耐折度则是在细小纤维加入量的某一范围内增加明显,透气度及白度降低。PFI细小纤维和HCR细小纤维较之Valley细小纤维,更能提高成纸强度及降低透气度。     

聚乙烯醇纤维对纸纱原纸性能的影响

在麻浆中加入聚乙烯醇(PVA)纤维制备纸纱原纸,探究了抄造工艺条件对纸纱原纸性能的影响。结果表明,较优的抄造工艺条件为:PVA纤维添加量2.0%,聚酰胺环氧氯丙烷(PAE)添加量2.4%,两性聚丙烯酰胺(AmPAM)添加量0.05%,烷基烯酮二聚体(AKD)添加量0.18%,打浆度75°SR,压光线压力15 N/mm,经过湿压榨后,干燥温度为80℃。在此条件下所抄纸纱原纸的抗张指数为80.0 N·m/g,湿抗张指数为32.8 N·m/g,撕裂指数为14.7 mN·m2/g,耐折度为1498次,平滑度为41 s,柔软度TS7值为53.8,伸长率为3.37%。     

一种打浆装置、系统及打浆方法

正申请公布号:CN 112482073 A发明人:曾劲松陈克复申请人:华南理工大学目前,制浆造纸过程的打浆方法很多,包括低浓打浆(浓度为2%～6%)、中浓打浆(浓度为8%～20%)和高浓打浆(20%～35%)。常用打浆机有槽式打浆机和PFI磨(立式打浆机),槽式打浆机属于低浓打浆,通常打浆时间为90min的时候,打浆度可以达到88°SR左右;PFI磨为中浓打浆,当打浆时间为12 min后,打浆度可以达到69°SR,     

酶预处理对纤维打浆性能的影响

采用纤维素酶对漂白阔叶木浆进行预处理,研究了酶预处理工艺对纤维形态和打浆能耗的影响,并进一步分析浆料通过PFI磨打浆后的纤维形态变化,为酶预处理漂白阔叶木浆制备纤维素微纤丝(CMF)提供理论指导。结果表明,酶预处理并没有明显改变纤维形态,但经PFI磨打浆后的纤维更易被切断和分丝帚化,纤维润胀程度得以提高,且当酶用量8 U/g,打浆度达到50°SR和68°SR时,浆料的扭结纤维含量相比未经酶预处理的对照样分别减少了17. 2个百分点和16. 2个百分点,细小纤维含量分别增加了20. 8个百分点和17. 6个百分点;此外,酶预处理能显著降低磨浆能耗。当酶用量8 U/g时,打浆度达到50°SR和68°SR时,打浆能耗相比未添加酶的对照样分别节省了50%和33. 3%。     

天丝对碱锰电池隔膜结构性能的影响

通过Valley打浆机制备不同打浆度的原纤化天丝纤维,与合成纤维、植物纤维混合抄造碱锰电池隔膜纸,研究了天丝打浆度、加入量对碱锰电池隔膜纸的孔径结构、吸液保液及强度性能的影响,并与不含天丝纤维的隔膜纸的孔径分布进行了对比。结果表明,经打浆处理的天丝纤维得到充分原纤化,分丝帚化较好,能形成几十至几百纳米直径的超细纤维;天丝纤维的加入及其较高的打浆度有利于提高纸张的抗张强度和减小纸张孔径,但加入量过多,打浆度过高不利于提高纸张的吸碱率和吸碱速度;较佳的天丝纤维添加工艺为打浆度35~45°SR、添加量10%~15%。     

打浆对思茅松纤维动态力学性能的影响

本文通过对云景思茅松硫酸盐浆进行打浆和抄纸实验,考察了纤维形态在打浆过程中的变化规律;研究了不同打浆方式、打浆度对成纸动态力学性能的影响。结果表明:PFI打浆有利于提高思茅松纤维成纸的抗张强度和耐破强度;Valley打浆对纸页动态力学性能的影响要明显优于PFI打浆;思茅松纤维有利于提高纸页的动态弹性模量和损耗因子。     

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.     

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.