蛋白质和淀粉对面团流变学特性和淀粉糊化特性的影响

以3个筋力不同的小麦粉为材料,利用分离重组方法,在保持小麦粉其他成分不变的情况下,组成不同面筋蛋白和淀粉含量的配粉,研究面筋蛋白和淀粉添加量对面团流变学特性和面粉糊化特性的影响。结果表明：随着面筋蛋白添加量的增加,3种筋力小麦粉配粉的面团稳定时间和粉质质量指数均呈升高趋势,峰值黏度、低谷黏度、最终黏度、稀懈值、回生值等总体呈下降趋势。小麦粉添加淀粉后,面团稳定时间和粉质质量指数均呈下降趋势,峰值黏度、低谷黏度、最终黏度、稀懈值、回生值等总体呈升高趋势。面筋蛋白和淀粉对小麦面团吸水率和面粉糊化温度的影响均较小。不同筋力小麦粉配粉各品质指标总体变化趋势一致,但变化幅度有一定差异。     

不同出粉率小麦粉矿物质含量及其加工品质研究

为探讨不同出粉率小麦粉矿物质含量及其加工品质的变化规律,选取优质中筋小麦为原料,利用布勒试验磨粉机制备出粉率分别为66%,68%,70%,72%,74%,76%和78%的小麦粉,分析其矿物质含量及加工品质。结果表明,随出粉率的提高,小麦粉矿物质中钾、镁、铁、锌含量均显著升高(p0.05),而钙含量无显著变化;小麦粉灰分、粗蛋白、膳食纤维含量均显著升高(p0.05),而水分和粗淀粉含量显著下降(p0.05);小麦粉破损淀粉值、沉淀值、粉质吸水率均显著提高,而淀粉糊化的峰值黏度、低谷黏度、终值黏度显著降低(p0.05);面筋指数和崩解值呈先增大后减小的变化规律;面筋含量、面团形成时间和稳定时间无显著变化。研究可为充分利用小麦资源、提高面粉企业经济效益提供理论支撑。     

糯小麦配粉对小麦粉及面包品质影响的研究

采用不同的配比将糯小麦粉加入到小麦粉中,通过测定一系列小麦粉指标和面包指标,研究了糯小麦配粉对小麦粉及面包品质的影响.结果表明:随着糯小麦粉比例的增加,支链淀粉含量、支直比、湿面筋含量、沉降值、弱化度增加;直链淀粉含量、总淀粉含量、降落数值、形成时间与稳定时间下降;小麦粉的峰值黏度、最终黏度与回升值都逐渐降低,而糊化温度变化不显著;将5%～10%的糯性小麦粉添加到面包粉中生产面包,面包的体积与综合得分略有下降,但面包的吸水率与保水性能增加,抗老化性能有所增强,有利于面包货贺期的延长.     

微波处理参数对发芽小麦理化特性的影响

在实验室条件下研究了微波处理参数中辐照前的润麦时间及微波辐照时间对发芽小麦品质的影响。结果表明,微波处理能改善发芽小麦的品质。辐照时间为30~90 s时,对发芽小麦各项品质参数的改善不明显;辐照时间为180 s时,虽然能大幅度提高降落数值、峰值黏度和面筋指数,但对湿面筋含量、面筋水合能力均造成不利的影响。最大程度改善发芽小麦品质的微波辐照时间是120~180 s。润麦时间为30 min时,微波处理后发芽小麦的降落数值、峰值黏度没有显著性变化;润麦时间大于30 min时,微波处理后发芽小麦粉的湿面筋含量趋于稳定,但面筋指数逐渐增大。微波辐照前的最佳润麦时间是30~60 min。     

球磨处理对小麦淀粉理化性质的影响

该文以小麦淀粉为原料,采用行星式球磨机对小麦淀粉进行机械损伤,通过对不同球磨处理时间下小麦淀粉的损伤淀粉含量、沉降体积、析水率、透明度以及溶解度和膨润力等指标的测定,得出:随着球磨时间的延长,小麦淀粉的溶解度、膨润力、析水率和损伤淀粉含量均显著增加,淀粉糊的峰值黏度、谷值黏度、最终黏度、衰减值和回生值均呈明显下降趋势;凝胶的硬度、脆度、黏附性、弹性和咀嚼性也随球磨时间的增加而下降。     

超微粉碎对小麦粉品质特性影响的研究

为探讨超微粉碎对小麦粉品质及面团流变学特性的影响,提高小麦粉制作面制食品的适宜性,选取优质强筋小麦样品,采用布勒实验磨粉机进行研磨制粉,再利用气流粉碎机对小麦粉进行超微粉碎处理,得到6种不同粒度的超微粉碎小麦粉样品,分析超微粉碎小麦粉品质及面团流变学特性(粉质参数)。结果表明:随着小麦粉粒度的减小,湿面筋含量、干面筋含量、降落数值均显著降低,破损淀粉含量、沉淀值、吸水量均显著提高(P0.05);淀粉糊化的峰值黏度、面团稳定时间、粉质质量指数均呈先增大后减小的变化规律。当小麦粉颗粒粒径D_(50)由43.07μm减小至25.81μm时,其淀粉糊化的峰值黏度由136 RVU显著增加至149RVU;当小麦粉颗粒粒径D_(50)由43.07μm减小至15.22μm时,其面团稳定时间由10.6 min增加至14.8 min。因此,综合考虑超微粉碎对小麦粉蛋白质品质、淀粉品质和面团稳定性的影响,采用超微粉碎技术对小麦粉进行适度加工,粒度(D_(50))达到25μm左右时,可以显著改善其淀粉糊化特性与面团加工特性。     

不同粉路小麦面粉理化性质与流变学特性分析

以15个不同出粉口小麦粉为样品,采用宏观理化表征与微观显微技术相结合的方法测定其特性。结果表明:M粉的前中路易糊化,其峰值黏度、低谷黏度、最终黏度、稀懈值、回生值比较高,其次是B粉的前路,而M粉的后路、B粉的后路、XF粉与T粉糊化指标相对较低,品质较差。面筋蛋白含量高的小麦面粉的吸水率、形成时间、稳定时间和粉质质量指数也相对较高,面筋蛋白含量对面团稳定时间影响很大,但相同筋力不同粉路的小麦面粉变化幅度不同。旨在为提高面粉品质分析与控制提供理论依据。     

微波辐照对发芽小麦理化特性影响的初步研究

在实验室条件下研究了微波辐照对不同品种、不同发芽时间的小麦样品其理化特性的影响.结果表明,随发芽时间延长,小麦及小麦粉的降落数值减小,表征小麦粉糊化及黏度特性的指标(面糊峰值黏度、峰值温度、崩解值、回生值)降低,面团的耐搅拌特性弱化,稳定时间缩短.微波辐照改善发芽小麦品质的作用非常明显,尤其对发芽时间短的小麦样品,可以显著增加其降落数值和峰值黏度,增强面团的搅拌稳定性.研究结果初步证实了微波辐照改善发芽小麦品质的可行性.     

重力分级前后不同小麦的理化特性分析

分别从2条小麦制粉生产线的重力分级去石机进出口在线取得小麦样品进行实验制粉。结果表明:分级后重质小麦中饱满籽粒含量增多,小麦粉的加工精度提高,品质特性得到改善,麦谷蛋白与醇溶蛋白含量虽稍有下降,但面筋指数提高,面团的形成时间及稳定时间延长,降落数值以及峰值黏度、最低黏度和最终黏度等指标均有不同程度的提高。轻质小麦的出粉率及小麦粉加工精度均降低,品质特性变差,轻质小麦中不饱满籽粒含量越多,差异越显著。     

发芽状况及热处理对小麦淀粉品质量影响的研究

以面筋强度不同的7个小麦品种为材料,分析不同发芽状况与热处理对小麦淀粉品质的影响。结果表明：发芽使α－淀粉酶活性激增,表现为降落值（FN）、膨胀势下降。70℃、90℃处理的发芽小麦,较未经热处理芽麦的降落值、膨胀势增高,说明适当高温处理能降低α－淀粉酶的活性。发芽及热处理对小麦淀粉含量影响较小。面筋强度不同的小麦品种表现基本一致。     

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.     

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.     

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.     

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.     

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.