高温高湿地区两种空调控温模式对稻谷安全储藏的影响研究

研究了温度为22 ℃、日开启时长13 h和温度为24 ℃、日开启时长24 h的空调控温模式下高温高湿储粮区稻谷储藏过程粮堆温度变化情况,比较了控温储藏前后稻谷水分和脂肪酸值的变化情况,分析了不同深度粮堆水平方向上各层温度变化差异,评估了利用空调控温实现准低温储粮的技术可行性。结果表明,在不同空调运行模式下,粮堆平均温度和最高粮温均缓慢升高。空调控温储粮对粮堆表层温度影响较大,对中层粮温影响较小,在空调控温储藏期间下层粮温可能受地坪温度影响。降低控温温度但缩短其控温时长的控温模式更加经济高效,采取22 ℃+13 h的控温模式比24 ℃+24 h的控温模式能够节约12.4%左右的用电费用。同时,控温空调对基础粮温较低的粮堆在仓温、表层粮温以及平均粮温的控制效果上较为明显,粮堆基础粮温对控温储粮技术的实施具有重要作用。     

三种方法对玉米局部发热处理效果研究

玉米在储藏过程中极易发热,危害储粮品质。针对中原地区玉米度夏发热问题,利用自动翻粮机处理、局部单管通风处理、人工挖沟翻粮处理,并以空调控温作为对照,研究玉米发热不同方法处理的效果。结果表明自动翻粮机可以将玉米温度由31.1℃快速将至22.1℃,玉米水分稳定在14.6%左右,粮情稳定。单管通风可快速将粮堆的湿热空气抽出,1 d粮温由40.6℃降至31.2℃,3 d降至27.5℃,并可将水分由15.37%降至14.39%,显著降低粮温与玉米水分。人工挑沟翻粮将发热粮暴露在空气中,4d后可将粮温由30.1℃降至27.6℃,水分15.01%降至14.03%,粮情稳定。利用空调控温可以将粮情长期保持稳定,12 d内粮温变化0.7℃,水分基本保持不变。     

浅圆仓小风量维持通风环流控温储藏粳稻试验

针对东北地区生态气候特点,应用小风量维持通风环流均温系统,开展浅圆仓粳稻控温储藏试验,结果表明:在浅圆仓内应用小风量维持通风环流系统能有效解决过夏期间粮堆表层和仓温较高的问题,全仓粳稻平均粮温控制在15℃以内,储藏期间粳稻水分及脂肪酸值变化较小,减缓了品质劣变,能确保粳稻的安全度夏和实现保质减损储藏。     

利用虹吸解决粮堆内局部发热的尝试

在粮食储存过程中，出现粮堆局部发热的情况，主要是新粮入库时杂质聚集导致局部粮食水分偏高，或储粮害虫在粮堆内滋生造成粮温升高。对发热粮堆必须及时处理，避免发生结块和霉变，影响整仓粮食品质。常见处理方法是单管通风降温，需要配合轴流风机，若发现储粮害虫活虫，还需要配合环流熏蒸，该法劳动强度高、耗电量大、用药量大、增加药物污染的可能性大，造成粮食的水分减量，本着绿色经济的原则，利用虹吸式通风原理处理粮堆内局部发热的试验。通过对粮堆内局部发热区域采用虹吸式通风处理，进行电子测温监测，发现降温灭虫的效果较为良好。     

华北地区高大平房仓稻谷控温储粮情况研究

对华北地区某高大平房仓的稻谷空调控温储藏情况进行了监测研究。结果表明：度夏期间,利用空调控温技术,仓房内空间温度和表层平均粮温可有效控制在22 ℃以下,但同一粮层不同位点温度差异大,在粮堆表层、西墙、南墙附近局部位置粮温仍会出现高于25 ℃的情况。受夏季外界环境高温影响,粮堆中心与侧壁附近温差10 ℃以上,存在“冷心热皮”引起的水分迁移现象。水分和温度在距离粮堆表层和仓房侧壁0.5 m附近易升高,成为霉菌易滋生的重点部位,同时,也是发芽率降低和脂肪酸值易升高的位置。因此,在控温储粮过程中需加强对粮堆表层和仓房侧壁粮情的监控。     

空调控温与充氮气调技术结合应用研究

研究空调控温与充氮气调技术结合应用,通过向充氮气调仓内空间通入冷气,使仓温保持在较低水平,减少外温对表层粮温的影响,达到整仓准低温储粮的目标。在对比研究试验仓与对照仓粮食品质及粮情变化情况后,得出采用空调控温与充氮气调技术相结合可以较好的控制整仓粮温,有效解决粮堆表层粮温上升过快、品质下降的问题。     

高大平房仓大豆安全储存试验研究

对大豆在夏季及秋冬季储藏期间的通风模式进行了试验研究,初步结果表明,分三阶段的通风模式1"轴流-轴流-离心"比模式2"离心-轴流-轴流"的储粮通风降温能效比高。研究还发现压盖仓比未压盖层的粮堆平均粮温低1.7℃和1.6℃;压盖仓比未压盖层的表层平均粮温低2.0℃和1.7℃。试验仓秋冬季通风后,储存大豆粮堆度夏的压盖仓平均温度低于18℃,未压盖仓的平均粮温低于20℃,整仓的大部分大豆处于准低温储粮状态,有利于延缓大豆储存品质劣变。经检测采用的大豆储存工艺和技术可安全有效的保持储存大豆的品质质量。     

广东地区浅圆仓玉米粮堆温度分布规律研究

为了解浅圆仓玉米储藏全年的粮堆温度变化规律,采用实仓调查的方法分析了广东地区一浅圆仓玉米入仓后第一年粮温在垂直方向和水平剖面上的变化,并通过温差和露点评估了粮堆表层的结露风险。结果表明：在垂直方向上,粮面下5 m范围内粮食受夏秋季太阳热辐射影响,温度超过20℃的时间在2个月以上,空调控温工艺能将仓温和表层粮温有效降低至25℃及以下,但在秋季空调关闭后,粮面下9 m范围的粮温有不同程度反弹升高;在水平剖面上,内外圈温差明显,温差大小受粮层深度和季节影响,同时受仓体周围遮挡物影响,阳光直射多的方向粮温高于其他方向;粮堆表层内圈范围在空调控温前结露风险较高。     

高大平房仓储粮内环流控温实验

内环流控温储粮技术目的是通过系统的改造,在环流风机的作用下,将粮堆"冷心"的冷源抽出,经过粮堆底部通风笼和环流保温管道,把冷气送入仓房粮堆上部空间,整个环流过程在闭合的循环系统中运行,不与外界空气接触,达到调节仓温和表层粮温的作用,从而实现控温储粮,取得了良好的经济效益和社会效益。     

华中地区高大平房仓内墙风管温控技术研究

华中地区高大平房仓夏季空调控温表层粮温一般不超过25℃,但受外墙高温辐射影响,仓内靠墙粮温长时间达30℃以上,粮堆四周升温快。为达到准低温储粮要求,夏季高温季节需要利用谷冷机进行复冷,不仅能耗大,而且会破坏粮堆原有冷芯。部分库虽实验性的安装隔热板或内环流管路,但成本较高、改造难度大、不易推广。中央储备粮南昌直属库在不做任何仓房改造的情况下,采取墙壁内侧粮堆埋插风管隔热的技术,利用现有仓房空调作为冷源,有效阻隔外墙高温,夏季无需谷冷机通风对粮堆进行复冷。     

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