不同加工工艺对“云抗10号”滇红工夫茶品质影响

为提高滇红工夫茶的品质特征,以云南大叶种茶树“云抗10号”鲜叶为原料,按滇红工夫茶的加工工艺,调整萎调、揉捻、发酵和干燥4个工序,制得10个滇红工夫茶样,并对茶样进行感官审评和内含成分测定。结果表明,所制茶样的水浸出物含量为38.12%～45.35%,游离氨基酸含量为3.59%～5.53%、茶多酚含量为19.67%～26.45%,茶黄素含量为0.06%～0.09%,茶红素含量为1.66%～4.30%、茶褐素含量为3.71%～4.83%。滇红工夫茶的品质是各个加工工艺互相作用的结果,以重萎凋8 h～12 h,揉捻28 min～30 min,发酵12 h～14 h,干燥温度先高温（110℃～115℃）烘干1 h后低温（80℃～85℃）烘干1 h的加工工艺制得的“云抗10号”工夫红茶综合品质最佳。综上,研究结果对提升滇红工夫茶品质提供了理论依据。     

玉米储藏霉菌活动预测的研究

研究了温度区间分别为＜23℃、23～28℃和＞28℃,相对湿度分别为70%～79%、80%～89%和＞90%,各条件组合储藏玉米的微生物活性值变化,总结出相应的线性方程,其线性相关性系数为0.85～0.99.通过恒定温度和湿度玉米模拟储藏微生物活性值预测和实际检测比较试验,结果表明,预测值与实际值的相关系数在0.79～0.96之间,微生物活性值预测平均偏差为5.7～27.8u,证明建立的模型可以较可靠地预测储藏玉米一个月的霉菌活动状况.     

乙酰丙酮衍生—液相色谱法测定浮瓜沉李中的甲醛含量

采用乙酰丙酮衍生,以高效液相色谱法测定啤酒中甲醛的含量。样品无需蒸馏,添加衍生试剂后在50℃保温20min即可供分析。色谱柱为Agilent ZORBAX SB-C18,流动相为乙腈/水(20/80),测定波长为412nm,采用标准加入法定量,在0～2．28mg/L范围内呈良好的线性,方法检出限为9μg/L,样品测定的RSD为1．0%～5．7%。本法具有灵敏度高,操作简捷,测定结果可靠等特点。除了优化测定条件的试验外,还对国内外22种品牌啤酒的甲醛含量作了测定。     

亚麻籽油中不同构型反式亚麻酸的气相色谱测定方法

为了定量分析亚麻籽油中α-亚麻酸(ALA)顺反异构体,采用SLB-IL111色谱柱,对气相色谱法测定反式亚麻酸(TALA)的分析条件(载气流速和升温程序)进行优化,并对所建立的方法进行评价。结果表明：载气流速选择0.3 mL/min;升温程序为60℃保持5 min,以20℃/min升温至175℃保持15 min,以1℃/min升温至180℃保持28 min,以0.2℃/min升温至185℃保持40 min;该方法可实现9c,12t,15t-C18∶3和9t,12c,15t-C18∶3的较好分离,分离度为0.9,其余各TALA的分离度在1.6～8.7之间;所建立的方法重复性好,测定加热亚麻籽油样时各异构体日间相对标准偏差(RSD)为3.16%～5.65%,日内RSD为2.00%～4.13%,检出限为0.678 2～0.879 0 mg/L,定量限为2.260 6～2.930 1 mg/L;各ALA异构体含量与峰面积之间线性关系良好,相关系数均为0.999 8。综上,所建立的方法可用于亚麻籽油中8种不同构型ALA顺反异构体的定量分析。     

共振光散射法检测肉制品中盐酸克伦特罗

目的:建立一种测定盐酸克伦特罗的新方法.方法:人血清白蛋白(HSA)与盐酸克伦特罗结合,用共振瑞利散射光法进行盐酸克伦特罗的检测.结果:在365nm处共振光散射增强强度与盐酸克伦特罗的浓度呈线性关系.以K2HPO4-NaH2PO4为缓冲体系维持盐酸克伦特罗测定溶液的pH=5.80,当温度为305.16K(28℃)和静置时间为30min时,方法的检出限为0.10μg/mL,线性范围为0.10～2.80μg/mL,线性相关系数r=0.995,方法精密度(RSD)和准确度(P)分别 2.98%～5.19%和92.50%～108.00%.结论:方法可靠、简便、快速,可直接测定样品中的盐酸克伦特罗.     

气相色谱-质谱法同时测定纺织品中28种有机氯载体

以二氯甲烷为萃取溶剂,超声提取30 min,内标法定量,建立同时快速测定纺织品中28种有机氯载体的气相色谱-质谱法。28种有机氯载体在0.01～1.00 mg/L范围内呈良好的线性关系,相关系数(R~2)均大于0.995,方法检出限为0.003～0.026 mg/kg,3个加标水平下的回收率为81.6%～116.7%,相对标准偏差(RSD,n=6)为0.9%～8.7%。该方法快速、操作简单、灵敏度高、定量准确,适用于纺织品中28种有机氯载体的分析测定。     

RP-HPLC法测定紫苏子、白苏子中乌索酸和齐墩果酸含量

采用反相高效液相色谱法测定紫苏子和白苏子中乌索酸和齐墩果酸含量,色谱柱为Kromasil C18柱(250 mm×4.6 mm,5μm),流动相为甲醇—水(87:13),光电二极管阵列检测器,检测波长210 nm,流速0.8 ml/min,柱温28℃。乌索酸进样量在0.10～4.00μg,齐墩果酸进样量在0.05～2.00μg时呈现良好线性关系,平均加样回收率分别为100.6%和98.7%,RSD分别为1.6%和1.2%。方法灵敏、准确,重现性好,可用于乌索酸与齐墩果酸含量测定。     

双柱双检测器气相色谱法同时测定烟草中28种有机磷农药

为了快速检测烟草中有机磷农药的残留量,考察了前处理条件和色谱系统(载气、温度等)分别对28种有机磷农药的回收率和分离度的影响,建立了双柱双检测器气相色谱法测定烟草中28种有机磷农药残留的方法.结果显示:①28种有机磷农药可分为2组,分别用DB-1701和DB-XLB毛细管柱分离;②有机磷农药检出限为0.009 ～ 0.029 mg/kg,回收率60.2% ～ 114.8%,相对标准偏差(RSD)0.83% ～ 9.75%.该法适合烟草有机磷农药多残留快速测定.     

芦荟果醋饮料的生产工艺

以芦荟为主要原料,采用液体深层发酵工艺,经酶解、酒精发酵和醋酸发酵制作芦荟醋,再辅以蜂蜜、蔗糖等调配成芦荟果醋饮料.酒精发酵的条件为温度28～30℃,pH 4.5～5.0,时间6～7 d,活化酵母菌的接种量为2%,醋酸发酵的条件为温度30～32℃,时间约5～6d,醋酸菌接种量为12%.     

富硒小麦苗醋饮料的研制

对富硒小麦苗醋工艺进行研究,富硒小麦苗汁调节糖度为13%后,添加0.1%的活性干酵母,28℃～30℃条件下发酵为4 d,残糖量为0.3%～0.5%;调节酒精发酵液初始酒精度为4.5%,接种10%醋酸菌生产发酵剂,32℃条件下发酵约5 d,发酵液总酸为8.7%～8.9%,取18%～20%澄清醋液,加入2.2%的蜂蜜、0.2%甜蜜素、0.3%食盐、0.2%姜汁混合均匀后杀菌。所得产品酸甜味适中,清凉爽口,柔和,具有淡淡的麦苗香和姜香。产品总酸含量(以乙酸计)为1.5%～1.8%,全硒含量为(45～50)μg/100 mL,有机硒为(40～44)μg/100 mL。     

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.     

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.     

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.     

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.