柜式喂料机出料流量控制方式的改进

为解决柜式喂料机在使用过程中存在料头、料尾时间过长等问题,利用分段控制方法对柜式喂料机的出料流量控制方式进行了改进.在料头阶段,通过PLC控制程序调整,将提升带的连续运行方式改为间歇式运行,并在提升带上设置积料过程以增加物料厚度,增大对定量管的供料能力;在料尾阶段,改变贮柜上光电开管位置以提前判断出料尾的到来,加快底带运行速度并改变拔料辊转向,使贮柜内物料快速出柜,减少料尾时间.应用效果表明,改进后解决了料头流量不足问题,保证了后续设备对物料流量的需求;料尾持续时间由改进前的近10 min缩短为1 min,物料流量控制稳定,较好地满足了工艺控制要求.     

提高梗丝处理段物料流量稳定性探析

在烟草行业制丝生产线都是流水线作业,自动化程度都很高。在生产过程中,在一些关键工序如加香加料、切丝、烘丝等,由于设备性能的原因为了保证产品的一直性和均匀性,提高品质产品,需要对物料流量进行限制,保证流量的稳定性,从而保证产品加工工艺参数的稳定性和产品性能的一致性。保证流量稳定性一般采用一台控制性电子秤+计量管+喂料机组成的供料系统。通过电子秤对物料进行计量的同时对喂料机进行控制,以达到稳定流量的目的。     

润叶加料工序含水率控制及相关算法研究

制丝生产线润叶加料工序在含水率控制过程中,采用传统的单闭环控制方式,仅凭操作人员的经验设定喷水量对物料进行加水,导致出口片烟含水率波动较大、控制失调,影响成品烟丝的内在质量.为此,采用带前馈-串级双闭环控制方式,对润叶加料工序的含水率控制及其控制算法进行了优化改进.该控制方式将来料含水率波动、加料比例、直喷蒸汽和温度等影响因素进行了精确的量化处理,并对其控制算法进行了改进完善,较好地解决了出口片烟含水率波动大的问题.实际运行效果表明,带前馈-串级控制系统是制丝生产过程中改善和提高片烟加工含水率稳定性的一种有效控制方案,改进后该工序点含水率控制合格率由原来的80％提高到99.8％以上,保证了成品烟丝质量.     

润叶加料供水流量稳定性研究

卷烟厂在制丝工艺中,润叶加料是十分重要的一道工序。该工序点的水分控制如何,直接影响到成品烟丝的吸味及内在质量指标。在含水率控制过程中,仅凭操作人员的经验设定喷水量对物料进行加水,经常出现出口水分波动较大,影响了烟叶的含水率,进而影响到成品烟丝的品质。为了给润叶加料筒的水分控制提供一个更好的方案,在结合技术改造的实际情况以及相关控制技术理论研究的基础上,在改造过程中提出采用增加稳压稳流系统控制方式,结合对润叶加料工序的含水率控制,较好地解决出口片烟含水率波动大的问题。实际运用效果表明,这是一种有效控制方案,改进后该工序含水率控制合格率大幅度提高,保证了成品烟丝质量。     

润叶加料喷嘴固定支架装置的改进

为解决润叶加料喷嘴安装角度无法量化等问题,对喷嘴固定支架装置进行了改进.设计了带表盘刻度功能的加料喷嘴固定支架,通过实验分析得到SJ型加料机最佳加料喷嘴轴向定位约为92.5°,即喷嘴喷射点距滚筒进料端约1 m,径向定位约为87.4°.应用效果表明,改进后喷嘴支架装置实现了加料喷嘴角度轴向和径向双方向的精确定位,操作简单方便,在相同工艺生产条件下,滚筒筒壁粘叶量由改进前的2.60 kg/批次降低至0.69 kg/批次,有效提高了加料均匀性和稳定性.     

切片与回潮系统的改进

为提高回潮后片烟含水率的稳定性 ,为后道润叶加料工序提供一个较稳定的片烟流量 ,对切片、回潮系统的控制方式进行了改进。将片烟流量由切片机的切片速度控制改为电子皮带秤流量控制 ;片烟含水率由通过操作人员设定加水量控制改为根据回潮后片烟含水率变化情况来调节加水量的自动控制。改进后效果明显 ,片烟流量的波动幅度由± 15 0 0kg下降到± 2 0 0kg以内 ;含水率波动由± 3%下降到± 1%以内     

过程能力分析在制丝工艺技术改进中的应用

为稳定、提高卷烟制丝质量,采用统计过程控制技术对制丝关键工序重要参数进行了评价,发现润叶加料、混丝掺配加香工序有待改进,对其进行改进后,再次利用统计过程控制技术进一步完善制丝质量考核体系。结果表明:①经改进后的制丝生产工艺关键指标过程能力指数PPK(Preliminary Process Capability Index)值平均提高了0.23,润叶加料均匀性标准偏差降低了56.5%,梗丝掺配均匀性由改进前的94.27%提高到97.38%;②改进前后批内、批间卷烟样品的感官质量得分波动值分别降低0.29和0.27分,说明改进后批内、批间的内在质量更趋于稳定;③完善制丝质量考核体系后,松散回潮热风温度、润叶加料入口流量、加料比例、烘丝热风温度、加香瞬时比例5个指标的平均PPK值提高6.1%。     

喂料机提升带速度控制模式的改进

为解决喂料机提升带频繁启停,导致设备机械损耗大等问题,对提升带的速度控制模式进行了改进。利用生产过程数据求出提升带输出物料流量的公式,基于该公式对提升带速度控制程序进行修改,同时在提升带电机变频器中增加逻辑控制功能。结果表明:改进后每批次提升带停机次数、高频(42Hz)运行时间及高频次数与改进前相比分别降低89.62%、75.94%和62.07%,提升带电机频率主要集中在26~29 Hz之间。新的流量控制法减少了提升带的启停次数,缩小了提升带速度变化幅度,有效提高了制丝生产线恒流量系统的控制水平。     

叶丝加料效果影响研究

为完善叶丝加料工艺技术,探索叶丝加料效果的影响因素,采用正交试验,考察了物料流量、滚筒转速、加料助喷压力、热风温度等参数对叶丝加料效果的影响,采用偏最小二乘法建立了试验参数与加料效果的回归模型。结果表明物料流量、助喷压力对叶丝加料效果有显著影响,各参数对料液有效利用率的影响大小为:物料流量助喷压力滚筒转速热风温度;对加料均匀性的影响大小为:助喷压力物料流量滚筒转速热风温度。建立的回归模型对料液有效利用率和料液含量变异系数有较好的预测效果,偏差分别为0.7%,0.5%。     

造纸法再造烟叶自动松散喂料机的设计与应用

为解决传统喂料机用于造纸法再造烟叶松散效果差等问题,根据先松散再喂料的原理,设计了具有自动松散功能的再造烟叶喂料机.该装置主要由进料带、自动松散装置、料仓、提升带4部分组成,再造烟叶通过进料带输送至自动松散装置,松散后的再造烟叶进入料仓,通过提升带进行均匀掺配,并可根据物料的流量进行调节.应用效果表明,自动松散喂料机有效解决了再造烟叶松散效果差等问题,松散后再造烟叶无明显造碎,松散率达到99.7％,实现了再造烟叶的自动松散及均匀掺配,提高了卷烟工艺品质.     

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