挤压玉米方便面的研究

本文研究了利用挤压法生产玉米方便面的工艺,分别考察了玉米粉添加比例、物料水分、螺杆转速和机筒温度对产品糊化度的影响规律。初步确定在玉米粉添加比例为15%时,最佳挤压参数为：物料水分30%,螺杆转速60r/min,机筒温度120℃。     

双螺杆挤压亚麻籽粕脱除生氰糖苷的研究

利用BrabenderDSE-25双螺杆挤压机对亚麻籽粕进行了挤压脱除生氰糖苷的试验,考察了加工条件(水分含量、加工温度、螺杆转速、喂料速度)对系统参数(扭矩、4区压力、5区压力)和脱毒效果的影响。结果表明,使用双螺杆挤压处理能达到使生氰糖苷降解脱毒的目的,合理的脱毒工艺参数:水分含量30%,加工温度80-120-130-140-150℃,螺杆转速120r/min,喂料速度18r/min,总氰化物脱除率为96.59%,生氰糖苷含量由257.85mg/kg降低至8.79mg/kg。     

菜籽饼乙醇脱毒脱油工艺研究

菜籽饼通过双液相萃取脱毒有较好的效果,但存在甲醇溶剂毒性大的缺点.为寻找环境友好溶剂,采用乙醇作为单相溶剂对菜籽饼进行脱油脱毒研究.通过单因素实验和正交实验考察分析了萃取时间、萃取次数、添加剂用量、总溶料比、菜籽饼水分含量及溶剂浓度等因素对脱壳冷榨菜籽饼脱毒脱油效率的影响.研究结果表明,较佳的工艺条件为:以加入少量添加剂的90%乙醇为溶剂,总溶料比为10:1(V/W),萃取温度为70℃,每次萃取时间为45 min,萃取6次.在此条件下,脱壳冷榨双高菜籽饼的硫甙脱除率达88%,单宁的脱除率为59%,菜籽粕的残油率在3%左右;脱壳冷榨双低菜籽饼脱毒后硫甙的含量用紫外分光光度法检测不出,单宁的脱除率达90%.     

应用均匀设计和响应面分析优化谷物早餐的挤压工艺

以小麦、燕麦和玉米粉为主要原料，以脆性和保脆性为主要指标，通过均匀设计得到挤压工艺中对品质影响较大的3个因素及其取值范围。再通过响应面分析对谷物早餐的挤压工艺进行优化，得出最佳的挤压工艺为：螺杆螺旋速度为334r／min；Ⅰ区温度为40℃；Ⅱ区温度为150℃；Ⅲ区温度为123．50℃；水分质量分数22．60％；蛋白质质量分数7．3％；脂肪质量分数8％。     

马铃薯米线挤压工艺的研究

以马铃薯全粉与籼米粉的复配粉为原料,采用双螺杆挤压工艺制作马铃薯米线。对马铃薯米线挤压加工过程中的原料水分含量、螺杆转速、挤压糊化温度(三区)和挤压成型温度(四区)进行分析研究。试验结果表明,4个因素对马铃薯米线品质的影响大小依次为原料水质量分数挤压成型温度挤压糊化温度螺杆转速。通过正交试验分析得出马铃薯米线最佳挤压工艺条件为:原料水质量分数38%、螺杆转速100 r/min、挤压糊化温度105℃、挤压成型温度92.5℃。以此得到的马铃薯米线综合评分为11.889,口感较好,蒸煮损失率降低。由此可预测,马铃薯米线的挤压加工具有一定可行性。     

双螺杆挤压对香菇膳食纤维色泽的影响

香菇膳食纤维采用双螺杆挤压机进行挤压处理.通过响应面分析方法对不同操作变量(螺杆转速、套筒温度、喂料水分)对产品色泽(以L、A、B值表示)的影响进行了探讨.总体而言,挤压处理使其L值低于原料组(对照组),而A值高于原料组,B值介于对照组及挤压组之间,在高螺杆转速、低套筒温度、高喂料水分操作条件下L、A及E值变化最小.     

挤压膨化提高含豆渣产品可溶性膳食纤维的工艺研究

主要以玉米粉,大米粉和豆渣粉为原料,用双螺杆挤压机进行挤压膨化,通过单因素试验和正交试验研究了螺杆转速、机筒温度、物料水分对提高产品可溶性膳食纤维含量及感官品质的影响。实验结果表明:在基础配方大米∶玉米=1∶3,豆渣的添加量8%的情况下,最佳挤压工艺条件为螺杆转速850 r/min,机筒温度150℃,物料水分14%。     

高湿挤压技术制备持香型仿肉制品工艺

以大豆分离蛋白和谷朊粉为挤压原料、天然呈味粉末油脂为香气调味料,利用高湿挤压技术制备持香型仿肉制品。通过固相微萃取-气相色谱-质谱联用技术对仿肉制品挥发性风味化合物进行定性定量分析,确定谷朊粉质量分数、水分质量分数、挤压温度及螺杆转速对挥发性风味物质保留率的影响。在单因素试验结果基础上,采用响应面法对高湿挤压工艺制备持香型仿肉制品进行优化,确定高湿挤压最优工艺参数为谷朊粉质量分数20%、挤压温度150?℃、螺杆转速300?r/min,响应值总挥发性风味物质保留率有最优值,为44.07%。而总挥发性风味物质保留率随水分质量分数的增加而减小,为不影响仿肉制品的咀嚼性,固定原料水分质量分数为60%。     

双螺杆挤压对大豆组织蛋白组织化度的影响研究

以大豆浓缩蛋白为原料,采用双螺杆挤压组织化技术,对大豆组织蛋白的组织化度进行了研究。结果表明：影响大豆组织蛋白组织化度的主要因素是温度,其次是螺杆转速与水分,喂料转速最小,最佳工艺是挤压温度180℃,水分38%,螺杆转速9Hz,喂料转速11Hz。     

双螺杆挤压技术膨化玉米粉研究

本文介绍了用双螺杆挤压膨化玉米粉的试验研究，分析了原料水分、粒度和螺杆转速对膨化性能的影响，得到了最节能的工作参数组合。     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.