冰温真空干燥过程中维持冰温的方法初探

冰温真空干燥技术结合了冰温技术和真空干燥技术诸多优点,具有很大的研究价值。然而,冰温真空干燥过程中冰温的维持是制约该技术发展的瓶颈。基于此,本文通过控制真空度、冷库和电加热板温度,初步探索出了一种在真空干燥过程中维持冰温的方法,以青鱼片为原料,以鲜度指标K值、干燥速率和复水率为实验指标,对冰温真空干燥、冷冻干燥和热风干燥进行了比较研究,研究表明,冰温真空干燥青鱼片的鲜度指标K值明显优于热风干燥,接近冷冻干燥;复水率比热风干燥稍好;干燥速率比热风干燥稍慢,比冷冻干燥快。     

黄粉虫冰温干燥研究

冰温干燥是结合冰温贮藏技术应运而生的新型干燥技术,该技术是将物料温度保持在冰温带内进行干燥,其目的是能够得到高品质的干燥制品,同时缩短干燥时间,降低干燥成本。文中以黄粉虫为研究对象,研究不同真空压力下的黄粉虫冰温干燥特性,得出了黄粉虫冰温干燥最适宜的真空压力,并与冷冻干燥进行了比较,为冰温干燥技术应用于生物材料的干燥提供参考。     

不同干燥方法对苹果片品质及微观结构的影响

以‘红富士’苹果为试材,采用真空干燥、冰温真空干燥、冷冻真空干燥3种方法进行处理,研究其对苹果的风味、营养物质以及微观结构的影响。结果显示,冰温真空干燥的复水性介于真空干燥和冷冻真空干燥之间,说明该种方式得到的苹果片疏松程度良好。冰温真空干燥后的苹果片的可滴定酸含量最高为1.28 g/100 g,基本与新鲜苹果的酸1.305 g/100 g接近(P>0.05),可溶性固形物质量分数最高为12.57%,对Vc的保留率达80.95%,比真空干燥高43.65%,比冷冻真空干燥高40.32%;总酚含量最高,说明该种方式得到的干制品品质最好。微观结构显示,冰温真空干燥得到的苹果片形变最小,与新鲜苹果的结构最为相近,有较为规则的孔状结构,冷冻真空干燥有较小的塌陷,真空干燥组织形变较大。该研究为干燥方式在食品中的应用提供了理论基础,为冰温真空干燥技术的应用做了进一步的拓展。     

蓝莓冰温微波真空干燥工艺研究

以蓝莓为原料,对蓝莓冰温微波真空干燥工艺进行了研究。通过响应面分析法确定蓝莓冰温微波真空干燥的最佳工艺条件,即微波功率为8.8 W/g,真空压力为654.1 Pa,干燥时间为4.8 h,装料盘转速为78 r/min。采用确定的冰温微波真空干燥工艺干燥蓝莓,与真空冷冻干燥和热风干燥蓝莓进行比较。研究表明,当干燥时间为4.8 h时,冰温微波真空干燥蓝莓的含水率为4.2%,比真空冷冻干燥速度快;冰温微波真空干燥蓝莓的感官品质优于热风干燥和真空冷冻干燥蓝莓,并且与热风干燥蓝莓差异显著。     

干燥方式对黑塌菜粉品质的影响

目的:以如皋市特产富硒黑塌菜为原料,研究冰温真空干燥对黑塌菜粉品质的影响。方法:将新鲜黑塌菜预处理后,冰温真空干燥至含水率(5.0±0.5)%,并以热风干燥、真空干燥和冷冻真空干燥为对照组,考察其理化指标。结果:冰温真空干燥维生素C含量为554.60 mg/100 g,保留率达83.96%,较热风干燥、真空干燥和冷冻真空干燥分别提高了43.11%,33.57%,1.61%;谷胱甘肽过氧化物酶酶活损失较小,纯度维持最好;总酚和总黄酮保留率分别为59.69%和60.58%,整体优于其他3组;微观结构方面,冰温真空干燥组菜粉粉末分布均匀,表面光滑平整、碎屑少;相较其他3组,冰温真空干燥组菜粉能够保持原有深绿色泽,复水性和溶解度相较于热风干燥和真空干燥有所提高。结论:冰温真空干燥对黑塌菜粉品质影响最小,营养品质最高。     

冰温真空干燥海鳗鱼片的鲜度和挥发性成分的对比研究

本实验以海鳗鱼片为研究对象,采用高效液相色谱仪和气质联用仪,研究了冰温真空干燥海鳗鱼片的鲜度和挥发性成分的变化,同时与真空冷冻干燥、热风干燥做了实验比较。结果表明:冰温真空干燥鱼片与鲜样相比,鲜度变化不大;挥发性成分含量有所降低;酸价即脂肪氧化程度增加。冰温真空干燥样品和真空冷冻干燥样品的K值分别为2.28%和2.04%,两者差异性不显著,而热风干燥样品的K值最高为26.64%。同时冰温干燥样品中IMP含量也明显的高于另外两种干燥样品。海鳗肌肉中对风味起主要作用的是羰基化合物和醇类,经过干燥之后冰温真空干燥样品中共检测出11种羰基化合物,占总挥发性成分的38.18%,与新鲜样相比含量有所降低。脂肪酸价方面,新鲜样品、冰温真空干燥样品、真空冷冻干燥样品、热风干燥样品的酸价依次为1.22、1.74、3.60、4.33。     

三种干燥方式对罗非鱼片风味物质的影响

以新鲜罗非鱼片为原料,采用高效液相色谱仪、气质联用仪、原子吸收仪等研究了三种干燥方式下(冰温真空干燥、真空冷冻干燥、热风干燥)鱼片鲜度、挥发性成分、有机酸和无机盐离子的变化。结果显示:新鲜鱼片的K值为2.83%,冰温真空干燥鱼片和真空冷冻干燥鱼片的K值分别为3.87%和4.29%,两者无显著性差异(p<0.05)。与其他样品相比,热风干燥鱼片K值较高,为22.69%。同时冰温真空干燥样品中肌苷酸(IMP)含量也明显的高于另外两种干燥样品。在罗非鱼片中对气味起主要作用的是羰基化合物。在新鲜样品、冰温真空干燥样品、真空冷冻干燥样品、热风干燥样品中分别共检测出11、8、10、13种羰基化合物,它们的百分总量分别36.36%、14.33%、20.03%和28.60%。有机酸和无机盐离子方面,与新鲜样含量相比,干燥样品中有机酸含量均有所增加,无机盐离子含量均有所下降,但冰温真空干燥样品变化幅度最小。综合以上几种指标,可以看出冰温真空干燥的效果要优于真空冷冻干燥和热风干燥。     

草鱼片冰温真空干燥特性及数学模型

本文以草鱼片为试材,研究了不同真空压力(600~700、1100~1200、1600~1700 Pa)、不同物料厚度(3、5、7 mm)条件下草鱼片冰温干燥特性,通过水分比的变化拟合草鱼片冰温干燥数学模型。实验结果表明:真空压力和物料厚度均对草鱼片冰温干燥的速率有较大影响,真空压力越低、草鱼片厚度越薄,干燥用时越短。Midilli模型能较好的模拟草鱼片冰温真空干燥过程,Midilli模型的R2>0.997,χ2<0.08‰,RMSE<0.85%,模型预测值与实验值很好吻合,可以用来描述草鱼片冰温干燥进程。     

温度对真空干燥海鳗的鲜度和滋味影响

实验以海鳗鱼片为对象,研究了不同温度对真空干燥海鳗鲜度和滋味的影响。实验设置了5种干燥温度,分别为:14℃(方式I)、8℃(方式II)、3℃(方式III)、冰温(方式IV)和-3℃微冻(方式V)。结果表明,在5种真空干燥温度下,干燥速率随温度下降而逐渐降低,含水率则逐渐升高,鲜度指标K值在-3℃真空干燥下最小为1.05%接近新鲜样品,肌苷酸(IMP)含量在冰温真空干燥下最高为1.30 mg/g,优于其它干燥温度,其中在-3℃时仅有0.46 mg/g,对游离氨基酸和主要呈味游离氨基酸而言,冰温真空干燥也优于其它温度的真空干燥,增加量分别为22.61%和22.59%。因此,对于5种温度来说,-3℃真空干燥新鲜度最好,但滋味物质含量较低,而冰温真空干燥在获得较好鲜度的同时,滋味物质肌苷酸和游离氨基酸含量也处于较高水平。     

冰温真空干燥压力对猕猴桃切片干燥品质的影响

以去皮的猕猴桃切片为试材,利用冰温真空干燥技术对其进行脱水处理,研究不同干燥压力(150、350、550 Pa)对猕猴桃切片的干燥速率及干燥后品质的影响。结果表明,冰温真空干燥技术可以最大限度的降低营养物质的损失。干燥压力为350 Pa时的干制品品质最好,猕猴桃切片的失水率和糖度分别为70.6%和24.5%,而复水比、V_C含量、色差值分别为4.75、110 mg/(100 g)和20.35。表明冰温真空干燥技术具有良好的应用前景。     

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.     

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     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press