热风室烤房与三段式烘烤工艺配套研究初报

热风室烤房（见本刊９１．４介绍）与三段式烘烤工艺有很强的互补性，初步研究结果表明，它比普通烤房三段式烘烤、普通烤房传统烘烤公斤烟均价分别提高０．３０元、０．４８元，节煤２４．５％。二者配套是提高烟叶烘烤质量的重要技术措施，有很高的推广价值。     

云南省立式炉新型节能烤房特点及推广应用效果

本项目针对全省现有烤房结构不够合理，性能不够优良，操作不便，调控不灵，能耗高，不适应优质烟叶烘烤的现状，实施烤房的研究和创新，经博采众长，技术集成，多点试验，反复设计，筛选出结构合理，调控灵活，操作方便，安全，增质节能显著，环境效益显著，改造成本低的“立式炉热风室新型节能烤房”和“立式炉平板式烤房”在全省推广应用，并取得了显著的经济效益，生态效益和社会效益。     

变频电机对密集烘烤烟叶质量的影响

为了解决密集烤房风机风速风量过大的问题,对密集烤房循环风机加装变频器,研究各烘烤阶段不同变频频率对烟叶烘烤质量的影响。结果表明,烘烤过程中烤房烟叶叶隙间风速能相对稳定在0.2～0.5 m/s范围内,变黄和定色时间整体拉长10 h,烟叶外观质量得到提高,橘黄烟和成熟度比例均提高7个百分点,疏松度增加4个百分点,烟叶内在化学成分得到改善,总糖和还原糖分别提高1.1个百分点和3个百分点,淀粉含量降低0.7个百分点,烟叶感官评吸质量明显转好。     

对热风循环烤房使用过程中若干技术问题的探讨

在烤烟烘烤中，利用热风循环烤房具有投资少，排湿能力强，烟叶变化均匀一致，烘烤时间短，成本低，烤后原烟外观质量好等特点，作者对热风循环烤房使用过程中存在的主要问题进行了分析。并提出了相应的解决办法，同时，对下部叶的烘烤提出了主要技术要点，还对热风循环烤房的使用提出了改进措施。     

普通烤房的智能化改造与应用

在普通烤房的基础上,通过增加热风循环和温湿度自控装置,进行了烤房的智能化改造.改造后的4m×4m×5.7m和2.7m×2.7m×5.7m两种型号智能化烤房烘烤期间的底棚与顶棚的垂直温差均显著低于普通烤房,智能化烤房与普通烤房的垂直温差差异以定色期的最大,平均为3.84℃,烘烤期间两种型号智能化烤房的垂直温差差异不显著;两种型号智能化烤房烘烤期间的平面温差均显著低于普通烤房,智能化烤房与普通烤房的平面温差差异以干筋期的最大,平均为1.06℃,烘烤期间两种型号智能化烤房的平面温差差异亦不显著;两种型号智能化烤房烘烤的烟叶均价和上中等烟比例平均分别增加3.33元/kg和27.99%,烟叶鲜干比和烘烤成本平均分别降低2.43和0.42元/kg,原烟外观质量也明显优于普通烤房.     

不同类型烤房的烘烤效果比较

以烤烟品种云烟87为材料,对湘密一号、小加密和普改密内置式3种类型的密集式烤房与普通烤房在烘烤后烟叶的质量、烘烤成本、产值等方面进行了比较.结果表明,3种类型的密集式烤房在烘烤能耗、上中等烟比例、外观质量、均价、产值等方面均优于普通烤房;湘密一号、小加密、普改密烤房每千克干烟烘烤能耗分别比普通烤房降低33.76%、22.94%和22.94%,上中等烟比例分别比普通烤房提高3.36%、4.35%和4.31%,烘烤后烟叶的净产值分别比普通烤房提高200.91、188.75和183.82元/667m2;其中湘密一号烤房装烟容量大,烘烤成本较低,且操作简便,烟叶烘烤收益好.     

密集烤房不同装烟方式对烟叶质量及效益的影响

为优化密集烤房装烟方式,充分发挥烤烟密集烘烤的优势,对散叶烘烤、烟夹持烟、烟竿编烟3种装烟方式烤后烟叶的外观质量、评吸质量、经济性状及烘烤能耗成本进行了比较研究。结果表明,烟夹持烟烤后烟叶橘黄烟比例比烟竿编烟烘烤高11.11%,散叶烘烤的杂色烟比例明显低于烟夹持烟和烟竿编烟;散叶烘烤和烟夹持烟烤后烟叶的评吸质量均优于烟竿编烟;散叶烘烤烟叶的中上等烟比例和均价最高;烟夹持烟烘烤的耗煤、耗电成本最低。综合烤后烟叶的经济性状和能耗成本,以烟夹持烟的效益最好。因此,在其他烘烤设施和烘烤技术配套的前提下,烟夹持烟可以替代传统的烟竿编烟;散叶烘烤是密集烤房装烟方式的发展方向之一。     

风机配置对热风循环烤房性能和烟叶烘烤质量的影响

比较了4种风机(60W、90W、120W和150W)对热风循环烤房水平向和垂直向温度、风速和烟叶烘烤质量的差异。结果表明,2.7 m×3.3 m小型5层烤房,装烟密度为竿距25 cm的情况下配置90~120W的风机,能显著提高热风循环烤房性能和改善烟叶烘烤质量。     

不同烘烤方式烘烤过程中烟叶表面腺毛分泌物变化的研究

为研究不同烘烤方式对烘烤过程中烟叶表面腺毛分泌物含量变化与损失的影响,选择了传统普通烤房、挂竿密集烤房、散叶密集烤房和框装密集烤房等4种烤房类型,采用GC-MS定性,GC-FID定量的方法,分析烟叶表面腺毛分泌物含量。结果表明,挂竿密集烤房和散叶密集烤房烤后烟叶腺毛分泌物总量分别约为传统普通烤房的50%和60%,并且损失主要发生在干筋期。框装密集烤房烤后烟叶腺毛分泌物总量与传统普通烤房相当。因此,框装密集烤房是解决目前挂竿密集烤房烟叶香气量损失较大的有效措施之一。     

《烟草科技》是读者的良师益友

《烟草科技》编辑部 :多年来 ,我是贵刊的热心读者 ,每期凡是农业方面的文章篇篇必读 ,重点文章反复看 ,有些还摘录到笔记本上。实践证明这对我们搞烤烟农业科研和技术指导起了重要作用 ,并取得了显著的经济效益和社会效益。特别是《烟草科技》1998年第 3期刊登的“烤烟热风循环烘烤技术研究”和 1998年第 4期的“热风循环立式炉烤房应用与示范”这两篇文章对我们研究改造烤房启发帮助很大。烤房改造是多年来研究的主要课题 ,参考这两篇论文的研究成果结合本地的实际情况 ,我们采用了热风循环立式炉 ,又配合平面炕 ,其结果是节约了能源 ,且…     

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.     

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.