酶转化淀粉熬胶工艺的优化

利用α-淀粉酶对玉米原淀粉进行改性,研究了酶转化淀粉熬胶的工艺条件。通过实验确定了酶转化淀粉熬胶的最佳工艺条件为：α-淀粉酶用量为0.1×10-3,酶转化淀粉熬胶糊化温度为75℃,杀菌温度为98℃,加料顺序采用先α-淀粉酶后淀粉、间隔搅拌时间为2 min。在此工艺条件下生产定量为78 g/m2轻型纸,纸表面强度平均提高了75%,平滑度平均提高了16%,Cobb值由平均35 g/m2降低到平均28 g/m2,降低了20%。     

表面施胶酶在大型纸机上的应用

太阳纸业天章#19机（抄宽4950mm、设计车速1300m/min）使用表面施胶酶后,生淀粉由使用氧化阳离子木薯淀粉转变为木薯或玉米原淀粉,减少了生淀粉氧化阳离子化的过程,实现了节能减排并降低了表面施胶胶料成本。在保证施胶质量的基础上,81g/m2涂布原纸表面施胶胶料成本降低了86.4元/t纸,下降幅度达42.1%。     

葡萄糖/葡萄糖氧化酶抗菌纸及抗菌性研究

葡萄糖氧化酶是氧化葡萄糖的专一催化酶,具有脱氧、杀菌的功能。通过定性和定量抗菌实验方法研究了葡萄糖/葡萄糖氧化酶体系在以淀粉作为载体和不混合淀粉时施涂于纸张表面的抗菌效果。定性抗菌实验表明,葡萄糖/葡萄糖氧化酶抗菌纸具有良好的抗菌效果。而定量检测结果表明,pH等于5.5时,35℃反应10min,不添加淀粉时,葡萄糖氧化酶最小的抑菌浓度约为70U/m2,葡萄糖足量时,酶用量越高,抗菌率越好;添加0.7g/m2淀粉后,最小抑菌浓度提高到约650U/m2。淀粉对葡萄糖/葡萄糖氧化酶体系的抗菌效果有较大影响,主要原因是淀粉能够促进细菌的繁殖。     

酶转化淀粉在轻型纸表面施胶中的应用

使用α-淀粉酶制备了高浓度、低黏度的淀粉胶液,用作轻型纸表面施胶剂。最佳制备工艺条件为：α-淀粉酶加入量0.02%（对绝干淀粉）;温度80℃时保温20 min;快速升温到98℃,保温30 min。所得产品固含量为9.0%,60℃时黏度5.5～6.5 mPa·s。用于60 g/m2轻型纸表面施胶时,成纸表面强度提高23.2%,施胶成本吨纸节约33.67元。     

α-淀粉酶在轻型纸表面施胶中的应用

使用α-淀粉酶制备了高浓度、低黏度的淀粉胶液用作轻型纸表面施胶剂。最佳制备工艺条件:α-淀粉酶加入量0.02%对绝干淀粉)、温度80℃时保温20min、快速升温到98℃保温30min。所得产品固含量9.0%,60℃时黏度5.5～6.5mPa.s。用于60g/m2轻型纸表面施胶时,成纸表面强度提高23.2%,施胶成本吨纸节约33.67元。     

酶转化淀粉在我厂表面施胶中的应用

我厂原采用玉米淀粉加次氯酸钙而制得的氧化淀粉作为表面施胶剂。纸经处理后,一些指标明显改进,但仍存在一些问题：①纸表面粗糙,掉毛现象较多;②挂胶量少,浆耗高;③溶解时有一些不溶的颗粒,堵塞管路,给生产和操作带来麻烦;④氧化淀粉渗透性强,成纸表面的施胶膜不均匀。根据存在的问题,我们于1997年上半年就开始改用酶转化淀粉作表面施胶剂,并一直沿用至今,下面将对该施胶剂作一具体介绍。1α─淀粉酶的特点2应用试验2.1原料玉米淀粉,杀菌剂,α─淀粉酶。2.2实验步聚在稀释罐中打入半罐清水,倒入玉米淀粉,开动搅拌器。将已…     

淀粉替代剂在酶转化淀粉表面施胶中的应用探讨及效果

用玉米淀粉替代剂替代部分玉米淀粉用于文化用纸的表面施胶。应用研究结果表明：酶转化淀粉熬胶加入部分玉米淀粉替代剂后,成纸的Cobb值、表面强度和平滑度与试验前相当,但降低了生产成本;以定量为80 g/m2胶版印刷纸为例,随着替代比例的增大,纸张质量并未出现大的波动,但是采用玉米淀粉替代剂替代玉米淀粉后,胶液黏度稍有增大,随比例增大胶液稳定性降低;因此最终替代比例确定在17.2%,吨纸生产成本降低了22.58元。     

酶改性淀粉的添加对纸张物理强度影响的研究

通过添加原淀粉酶转化剂,对玉米原淀粉进行生物改性,测定了改性后玉米淀粉的黏度,探讨了添加该改性淀粉对纸张物理强度的影响,并将其与氧化淀粉的性能作了比较。实验结果表明,淀粉酶制剂能有效地降低原淀粉糊化后的黏度,当原淀粉酶转化剂添加量由0增加至1.0‰时,原淀粉糊化后黏度由11000mPa.s降低至135mPa.s;对于淀粉酶制剂用量为0.5‰,酶改性淀粉用量为2%所抄造的定量为80g/m2纸张,其抗张强度和撕裂度比原样均提高了30%左右,且效果与氧化淀粉作用相当;酶改性淀粉工艺简单易行、使用方便,可降低生产成本,具有较好的实用性和高效性。     

TEMPO/NaBr/NaClO体系氧化酶解淀粉及其表面施胶

用α-淀粉酶对玉米原淀粉进行酶解预处理,酶解后的淀粉再通过2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)氧化体系进行改性,并将改性后的淀粉用作造纸表面施胶剂。研究发现,在pH值9.5、温度5℃、反应时间2.0 h、TEMPO用量1.0 mg/g、NaBr用量0.01 g/g、NaClO用量2.00 mmol/g的条件下,TEMPO/NaBr/NaClO体系氧化酶解淀粉可使改性淀粉的羧基含量为5.06%;将改性淀粉作为表面施胶剂,当表面施胶量为4 g/m2时,与未施胶原纸相比,纸张抗张强度和表面强度的增幅分别为51.6%和334%。     

酶转化淀粉在文化纸表面施胶中的应用

本文探讨了酶转化淀粉表面施胶对高白双胶纸和静电复印纸等文化纸表面强度、挺度等关键质量指标的影响。     

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