低温等离子体处理对鲜参切片的杀菌效果及表面色泽的影响

目的 探讨低温等离子体处理对鲜参切片表面微生物的杀菌效果,以及对鲜参切片表面色泽的影响,获得优化杀菌工艺条件,为鲜人参的保鲜贮藏提供新方法。方法 首先,以鲜参切片表面微生物的杀菌率为指标,考察放电电源功率(W)、等离子体处理时间(min)、气体流速(cm3/min)三个因素的杀菌效果,然后根据单因素试验的结果,应用三因素三水平响应面优化试验设计,获得最佳杀菌工艺,并测定低温等离子体处理鲜参切片的色泽变化。结果 低温等离子体处理鲜参切片的最佳杀菌工艺条件为：放电电源功率340 W、等离子体处理时间4.7 min、气体流速10 cm3/min,在此条件下的杀菌率为99.89%;影响因素的显著性大小顺序为: 等离子体处理时间>放电电源功率>气体流速,且鲜切参片经低温等离子体处理后色泽无明显变化。与酸性氧化电位水杀菌相比,低温等离子体处理的杀菌率提高了5.3%, 杀菌时间缩短了57%, 杀菌效果更好。结论：低温等离子体处理对鲜参切片表面微生物的杀菌效果显著,低温等离子体处理可以作为一种更高效、更省时的非热杀菌方法。     

介质阻挡放电参数诊断及对材料表面改性的研究

运用自制常压介质阻挡放电装置对PBT熔喷非织造布的表面进行改性实验,讨论了介质材料的介电常数、厚度、处理时间、放电气体等因素对改性效果的影响。结果表明,介质材料的介电常数越大,厚度越小,对材料的润湿性提高越大;在相同的实验条件下,氩气等离子体比空气等离子体对材料的改性效果更好;而等离子体处理材料时间一般控制在5min内为宜。     

丙烯酸微波低温等离子体引发PET接枝改性的研究

用丙烯酸微波低温等离子体对聚酯膜进行接枝改性,并通过依次改变丙烯酸微波低温等离子体处理气体压力、功率和时间三因素优化出了处理聚酯膜的最佳工艺条件,并用此工艺条件对涤纶织物进行了水洗效果测试,同时用红外谱图和电镜照片进行了表征。研究表明,丙烯酸微波低温等离子体对聚酯膜有刻蚀作用,处理后可将丙烯酸接枝到聚酯膜上,证明将丙烯酸气体的微波低温等离子体直接作用于材料进行表面改性是可行的。     

氧冷等离子体处理条件对杨木单板表面润湿性的影响

用氧冷等离子体对杨木单板进行改性处理,研究不同处理功率和处理时间下杨木单板表面润湿性和自由能的变化,结果表明:氧冷等离子体处理能显著改善杨木单板的表面润湿性.经不同条件氧冷等离子体处理后,杨木单板表面接触角下降率达70%～80%,表面自由能增加率达200%～400%.较优的处理条件为:处理功率200w,处理时间3min.     

等离子体处理对腈/棉混纺纱性能的影响

为改善腈/棉混纺纱吸湿性及染色性能,利用等离子体技术,以处理时间、输出功率、工作气体为因素,设计三因素三水平正交试验,优化处理工艺。利用扫描电镜(SEM)表征处理前后腈纶、棉纤维表面形貌,并测试处理前后腈/棉混纺纱的吸湿性、拉伸性能及染色性能。结果表明:等离子体处理后,腈纶和棉纤维表面粗糙度增加,表面碳元素含量下降,氧元素和氮元素上升;混纺纱的吸湿性和染色性提高,断裂强度无显著变化。等离子体处理腈/棉混纺纱的最佳工艺为:工作气体为氩气、输出功率300 W和处理时间3 min。     

棉织物的常压等离子体拒水改性处理

以六氟丙烯(C3F6)为处理气体,以氦气(He)为载气,在常压下实现等离子体准辉光放电.以此对棉织物进行表面改性处理,研究放电时间、功率、浓度等条件对拒水性能的影响.结果表明:织物与水接触角不随实验条件变化而明显变化,说明粗糙度相同时,水的接触角主要受织物的表面能影响;润湿时间随处理条件增强而增加,说明润湿时间主要受沉...     

等离子体诱导丙烯酸接枝改性聚丙烯熔喷非织造材料

为提高聚丙烯（PP）熔喷非织造材料表面的亲水性,针对PP表面化学惰性较大的缺点,通过氩气等离子体处理材料表面,然后进行丙烯酸接枝改性,获得了亲水性良好的PP熔喷材料。研究了不同气氛、处理电压和时间对等离子体处理的影响。同时,研究了接枝温度、时间和单体质量分数对丙烯酸接枝处理的影响。采用接触角测量仪、扫描电子显微镜和傅里叶红外光谱仪分别测试了等离子体和接枝处理前后材料亲水性变化、表面形貌及基团的变化。结果表明：在氩气等离子体处理电压为150 V、处理时间为180 s的条件下处理后,当接枝时间为90 min、接枝温度60 ℃、丙烯酸单体质量分数为60%时,样品接触角从140°下降至32°,材料表面亲水性最好。     

低温等离子体对蓝湿革表面改性的研究

为了从鞣制角度研究低温等离子体(LTP)在皮革表面改性中的应用,利用氧气(O2)作为放电气体产生的低温等离子气体,对蓝湿革进行表面处理.用光学显微镜得到了经LTP处理前后革样表面不同的形貌特征;用X射线光电子能谱(XPS)对革样表面氧含量进行分析,结果表明经LTP处理过的蓝湿革,表面氧元素含量最高可达21.93%,高于未经处理的19.91%;铬复鞣后用XPS对复鞣后革样表面铬含量进行分析,革样表面的铬含量由未经LTP处理的5.39%增加到处理后的12.82%.结论说明:低温等离子体对蓝湿革表面的改性可增加表面含氧基团如羧基的含量,从而增加铬复鞣后革样表面铬的结合量.     

用于气体和液体过滤介质的创新低压等离子体纳米涂层技术

介绍了低压等离子体技术及其涂层设备.利用多种混合气体等离子体涂层可使材料具有持久的亲水性;而创新的低压等离子体工艺通过物质单体聚合作用,可使沉积在材料表面的纳米涂层具有高等级的疏水性或拒油性.用低压等离子体技术对气体和液体过滤介质进行处理,可提高过滤介质的质量且可降低生产成本.     

用于调理鸡肉的大气等离子体冷杀菌工艺优化

本文采用大气等离子体放电技术处理调理鸡肉表面,在不损伤风味的情况下对其杀菌工艺进行研究。本研究以调理鸡肉的杀菌率和感官评价为指标,通过放电功率、处理时间、气体流量单因素实验探究冷杀菌工艺条件,并采用响应面法对其进行优化。结果表明,大气等离子体放电处理调理鸡肉的优化参数为气体流量为40 L/min,放电时间52 s,放电功率450 W,杀菌率达到96.34%±0.32%,与理论杀菌率相差3.04%。这些数据表明,大气等离子体技术可对食品表面进行非热处理,具有明显的杀菌效果。     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.