真空冷冻干燥绿芦笋护绿工艺研究

色泽是评价真空冷冻干燥绿芦笋质量的重要指标,本实验从漂烫和护绿剂浸泡处理两个环节对真空冷冻干燥绿芦笋的护绿工艺进行研究。运用U12(122×6)均匀实验研究不同漂烫条件对绿芦笋营养成分的影响,利用L16(45)正交实验研究不同护绿处理的护绿效果,最终得出真空冷冻干燥绿芦笋较优护绿工艺条件为:切分长度5～6cm,85～90℃条件下漂烫3.5～4min;0.3mol/L的Na2CO3溶液浸泡40s;护绿剂pH7.5、Zn(CH3COO)2浓度200mg/kg、CuSO4浓度50mg/kg,浸泡时间8h。     

含铜复绿剂对腌渍蕨菜的复绿效果及铜含量变化研究

目的确定腌制蕨菜复绿的最佳工艺条件,并比较复绿前后铜元素含量。方法以醋酸铜复绿剂不同浓度、不同烫漂时间、不同烫漂温度为因素的进行单因素及正交试验,采用色差仪测定复绿前后腌制蕨菜的色泽变化,利用火焰原子吸收分光光度计测定复绿前后腌制蕨菜的铜元素含量。结果醋酸铜复绿剂最佳复绿工艺条件为:烫漂温度95℃,烫漂时间8 min,复绿剂浓度200 mg/L,复绿前腌制蕨菜中铜元素含量为2.08mg/kg,复绿后铜元素含量为4.61 mg/kg。结论醋酸铜复绿剂对腌制蕨菜有复绿效果,最佳复绿工艺条件下蕨菜中铜含量虽符合林业行业限量标准,但含铜复绿剂也不宜使用过多。     

鸭儿芹护色工艺条件优化

以新鲜鸭儿芹为原料,利用碱液漂烫和护色剂对鸭儿芹进行护色,根据色泽和质地的感官评分,研究漂烫条件、护色剂种类和护色条件对鸭儿芹护色效果和质地的影响。研究结果表明,碱液漂烫和护色剂处理对鸭儿芹都有较好的护色效果。不同种类不同浓度的护色剂中,0.06%醋酸锌和0.3%植酸护色效果最为显著。鸭儿芹最佳漂烫工艺条件为90℃下1.0%Na2CO3溶液中下漂烫1min;最佳护色工艺条件为pH5的0.3%植酸+0.07%Zn(COOH)2溶液中浸泡20min。在此条件下漂烫和护色,鸭儿芹的色泽和质地最好。     

速冻小松菜加工贮运中护绿技术研究

为探索出口速冻小松菜加工贮运中适宜的护绿保鲜措施,以莎莉品种小松菜为试材,研究其速冻前复合液烫漂处理中碳酸氢钠和氯化钠浓度、烫漂温度和时间等因素对小松菜冻藏贮运(-18℃)中色泽的影响;同时对处理条件进行优化。结果表明,小松菜速冻加工中适宜的护绿处理条件为:0.10%碳酸氢钠+0.10%氯化钠复合液,在90℃条件下漂烫1.2min,并结合0.20%氯化钙溶液室温浸泡30 min+PE包装+速冻等综合措施,对产品冻藏期色泽护绿效果较好。     

桂花花色护色研究

采用3种方法:直接烫漂、护色液浸泡后烫漂、蔗糖溶液浸泡后烫漂,研究其对桂花的护色作用,比较选出最佳方法。烫漂后60℃条件下干燥。结果表明新鲜桂花花瓣用20%蔗糖溶液浸泡后90℃烫漂2min,干燥后色泽较好。     

鸭儿芹护色技术及质量控制研究

以鲜嫩鸭儿芹为原料,采用L9(34)正交试验,研究了不同用量不同种类护绿剂在不同漂烫条件下,对鸭儿芹护绿效果的影响及其过程中的质量控制,得出了最佳护色技术。结果表明,用300×10-6Zn2+护绿液,在pH8.5、95℃条件下漂烫1.5min,再用0.8%Ca2+溶液浸泡30min,护绿效果最好且能较好地保持原有质地。     

球磨法制备富硒绿茶粉工艺优化

以紫阳富硒茶成叶为原料,通过漂烫杀青、冷冻干燥和球磨等工艺制备富硒绿茶粉,在漂烫工艺中以茶叶成叶中硒元素含量为指标考察硒元素的流失情况,比较了冷冻干燥与40 ℃烘箱干燥的干燥效率,并选择球磨时间、研磨球大小球比和球磨转速三个因素,通过单因素和正交试验对制备工艺条件进行优化。实验结果表明,漂烫温度为100 ℃条件下,茶叶成叶中硒含量随漂烫时间延长而降低,由69.58 μg/kg(0 s)降低至64.72 μg/kg(60 s),损失率7%;16 h冷冻干燥鲜叶失水率为52.05%,40 ℃烘箱干燥失水率为49.52%。影响富硒绿茶粉颗粒粒径大小的因素依次为球磨时间>大小球比>球磨转速,球磨加工最优工艺为:球磨时间50 min,球磨转速800 r/min,大小球比1:6;采用激光粒度仪及扫描电镜对其表征,球磨颗粒形态断面清晰,粒径分布均匀,D₅₀值为3.25±0.35 μm,茶粉中硒含量为(63.18±4.22) μg/kg。该工艺条件下生产的富硒绿茶粉颗粒均匀,色泽翠绿,茶叶中硒元素保留度高。     

工业化宫保鸡丁产品中莴笋前处理加工品质关键技术研究

以莴笋茎干为原料,色泽和脆度为感官考核指标,通过对比漂烫温度、漂烫时间、漂烫液浓度和保护液的浓度对宫保鸡丁中配菜莴笋颜色及脆度的影响,确定工业化宫保鸡丁中莴笋最优护绿保脆参数。结果表明:漂烫温度85℃,漂烫时间1.5min,漂烫液的浓度为0.03%碳酸钠,保护液浓度为0.3%氯化钙,该参数条件处理后的莴笋能够在工业化宫保鸡丁中保持良好的颜色及脆度,使得其口感、风味、脆度和色泽几种品质最佳。     

枸杞嫩茎叶护绿技术及质量控制研究

以新鲜的枸杞嫩茎叶为原料,采用L9(34)正交试验,研究不同种类护绿剂在不同漂烫条件下,对枸杞嫩茎叶护绿效果的影响及其过程中的质量控制,得出最佳护色技术。试验结果表明:用Zn2 (0.04%)、Na2SO3(0.02%)的护绿剂,在pH为6.5、95℃条件下漂烫1.5min,护绿效果最好且能较好地保持原有质地。     

速冻小松菜安全护绿的小苏打复合液漂烫工艺研究

以新鲜小松菜为原料,研究其速冻前加工环节小苏打(碳酸氢钠)复合液漂烫护绿保鲜效果并优化其工艺参数,在单因素试验基础上,以冻藏期小松菜叶绿素a/脱镁叶绿素值a比值、总叶绿素含量与叶柄质构硬度的综合分值为评价指标,采用四因素三水平的中心组合设计,优化小苏打复合液漂烫护绿工艺参数。结果表明,小苏打复合液漂烫处理中各因素对小松菜护绿保鲜效应主次顺序为:小苏打浓度(p0.01)氯化钠浓度(p0.05)漂烫时间(p0.05)烫漂温度(p0.05),确定的最佳工艺条件为:碳酸氢钠浓度0.26%,氯化钠浓度0.31%,烫漂温度95℃,漂烫时间89 s时,在此工艺条件下,得到小松菜色泽与叶柄质构的综合分值为0.671 8,对速冻小松菜冻藏期的护绿保鲜效果较好。     

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.