PMAA非离子乳液纸张干强剂的制备及应用

研究了丙烯酸甲酯(MA)、苯乙烯(St)、丙烯酰胺(AM)及丙烯腈(NA)为原料，采用核—壳技术制取非离子乳液纸张干强剂的方法。将PMAA乳液加到草浆中，通过对纸张的环压强度、耐破度和撕裂度等的测定，发现当乳液用量为0．75％～1．0％时，可使纸张抗拉强度提高29．4％，耐破度提高96．4％，环压强度提高36．8％。     

PMAA阳离子乳液的合成及在造纸增强中的作用

以丙烯酸甲酯（MA），苯乙烯（St)，丙烯酰胺（AM），甲基丙烯酰氧乙基三甲基氯化铵（MTA）为原料，采用无皂乳液聚合法合成出了一系列阳离子共聚物（PMAA）乳液，将PMAA乳液加到草浆中，通过对纸张的环压强度，耐破度和撕裂度等的测定，发现当乳液的用量为0．75％时，其增强性能最好。     

MMA/DMC/AM/AA共聚物乳液的合成及其环压增强作用

以丙烯酰胺(AM)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)、甲基丙烯酸甲酯(MMA)和丙烯酸(AA)为主要原料,通过无皂乳液聚合制备了稳定且性能优异的两性MMA/DMC/AM/AA四元共聚物乳液纸张环压增强剂,并优化了合成工艺条件.通过傅里叶红外光谱仪(FT-JR)、热失重分析仪(TGA)、激光颗粒粒度分析仪(DLS)和扫描电镜(SEM)对MMA/DMC/AM/AA四元共聚物乳液纸张环压增强剂结构、胶膜热稳定性、乳液粒径及应用该乳液进行表面施胶前后的纸张进行了分析,并考察了MMA、AM含量和AA与DMC质量比对共聚物乳液环压增强性能的影响.结果表明,w(MMA)=1 5％,w(AM)=8.5％,m(AA)∶m(DMC)=1.5 ～2.0时,制备的共聚物乳液的环压增强性能优异;以共聚物乳液(质量分数为0.5％)和淀粉(质量分数5％)组成的表面施胶液对瓦楞原纸施胶时,施胶后纸张环压指数高达8.68 N·m/g,与施胶前相比提高93.8％.     

（BA—MMA—MTA）阳离子共聚物乳液的合成及对纸张增强的研究

该文以丙烯酸丁酯(BA),甲基丙烯酸甲酯(MMA)和2-甲基丙烯酸乙酯三甲铵盐(MTA)为原料,采用无乳化剂乳液聚合法,合成出了一系列BA-MMA-MTA阳离子共聚物(PBMM)浮液,测定了乳液的稳定性和转化率,找到了合成PBMM乳液的最优配方和条件,根据电镜观测,此乳液为球形粒子,粒径约为70-190nm.把PBMM乳液加到纸浆中,测定了纸张的耐折度、撕裂强度和环压强度等,我们发现,当PBMM乳液的用量为0.70%时,其增强效果最好.     

层间加填对瓦楞原纸强度性能的影响

以碳酸钙为矿物填料,选用苯丙乳液、羧基丁苯胶乳作为纸张黏合剂,全废纸浆抄造瓦楞原纸,对比了层间加填与浆内加填以及两种黏合剂对成纸物理强度性能的影响。结果表明:采用层间加填技术,碳酸钙的填加量为25%(对绝干浆)时,采用羧基丁苯胶乳作为黏合剂效果优于苯丙乳液,且当羧基丁苯胶乳用量为2%时,纸张的抗张强度、环压强度较浆内加填有较大提高。同时,通过分析对比两种加填方式纸张结构的SEM图可知,采用层间加填技术,使纸张形成的多层结构有利于提高纸张的物理强度指标。     

几种不同施胶剂施胶性能对比

用改性胶原蛋白乳液、苯丙乳液和AKD乳液三种胶液对瓦楞原纸进行表面施胶,对比考察三种施胶剂施胶后纸张的力学性能及吸收性变化。将改性胶原蛋白乳液与苯丙乳液进行复配施胶,当两者的比例为1：1时,此时纸张的各项性能最好,与未施胶纸样相比,纸张的抗张指数、环压指数分别提高了63.4%和79.2%,Cobb60降至40 g/m2。改性胶原蛋白乳液与AKD乳液复配施胶,两者的比例为3：1时,纸张的各项性能最好,纸张的环压指数、抗张指数分别提高了54.2%和47.7%。纸张Cobb60值则降为34.7 g/m2。将三种胶液与淀粉复配,或者两两复配施胶,其中以改性胶原蛋白乳液与苯丙乳液复配后效果为最佳。     

阳离子共聚物乳液的合成及在造纸增强中的作用

以丙烯酸甲酯（MA）、苯乙烯（St)、丙烯酰胺（AM）、甲基丙烯酰氧乙基三甲基氯化铵（MTA）为原料，采用无皂乳液聚合法合成出了一系列阳离子共聚物（PMAA）乳液，将PMAA乳液加到草浆中，通过对纸张的环压强度、耐破度和撕裂度等的测定，发现当乳液的用量为0．75％（对绝干浆）时，其增强性能最好。     

阳离子活性聚合物/AKD乳液的施胶和增强作用

以合成的阳离子活性聚合物作为高分子乳化剂,制备了阳离子活性聚合物/AKD乳液。研究了乳液制备过程的主要影响因素,并比较了阳离子活性聚合物/AKD乳液与传统AKD乳液对纸张的增强性能。结果表明,当m(阳离子活性聚合物)∶m(AKD)=0.30时可制得稳定乳液,乳液具有很好的施胶和增强效果,且明显优于传统的AKD乳液。当乳液(固含量为15%)以用量0.13%(对w=5%的淀粉溶液)进行施胶时,纸张施胶度可以达到40s,环压指数提高了13.6%,耐折度提高了185%。纸张表面的SEM分析显示,经阳离子活性聚合物/AKD乳液施胶后的纸张表面,纤维间的界面变的模糊,纤维结合更加紧密。     

层间加填中黏合剂的特性及复配比例对成纸性能的影响

以废纸抄造瓦楞原纸,选用重质碳酸钙为填料,苯丙乳液与两种取代度不同的阳离子淀粉为黏合剂,考察了黏合剂的种类、用量以及不同黏合剂的复配比例对成纸物理强度性能的影响。结果表明:采用苯丙乳液作为黏合剂的效果优于两种取代度不同的阳离子淀粉,而低取代度的阳离子淀粉又优于高取代度阳离子淀粉。当碳酸钙填加量为25%(相对于绝干浆),苯丙乳液与阳离子淀粉以1:4的比例复配,用量为2%时,虽纸张的抗张强度略有下降,但纸张的环压强度及内结合强度高于单独使用阳离子淀粉或苯丙乳液的纸张。     

无皂苯丙聚合物/AKD乳液表面施胶剂的制备与应用

以甲基丙烯酸(MAA)、苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)为单体,通过无皂乳液共聚反应制备了一种两性聚合物乳液表面施胶剂(ASAP)。以其为分散稳定剂制备了ASAP/AKD乳液表面施胶剂。以质量分数为0.15%的ASAP/AKD、质量分数为5%氧化淀粉表面施胶液,施涂量为1.2g/m2,对草木混合浆抄造纸张进行表面施胶,施胶度达113s。在ASAP/AKD乳胶质量分数为0.20%时,能显著改善纸张表面强度,耐折度、环压指数分别提高71.4%和40.7%。     

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.     

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.     

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.     

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.     

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.     

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