不同粒度区间小麦粉对半干面品质的影响

研究了四个不同粒度区间小麦粉对半干面品质的影响。结果表明,不同粒度区间的小麦粉之间的品质表现差异性显著(p<0.05),180~200目粒度区间小麦粉的粗蛋白含量、湿面筋含量和面筋指数均高于其他粒度区间小麦粉;破损淀粉和灰分含量随粒度减小逐渐增加;140~160目区间小麦粉的粉质质量指数最大,稳定时间最长,弱化值最小;140~200目区间小麦粉的吸水率差异并不显著。随小麦粉粒度减小,半干面的白度、吸水率、蒸煮损失率逐渐增加;140~160目区间小麦粉制作的半干面,其硬度最大,咀嚼性最好;160~180目区间小麦粉制作的半干面,其拉伸性能最好;180~200目区间小麦粉制作的半干面,其深层结合水比例最高,回复性、弹性、黏聚性表现最好,感官评分最高,适合制作半干面。     

不同粒度小麦粉对面团及馒头品质的影响

利用筛分的方法将小麦粉筛分为140～160目、160～180目、180～200目、200目以上4个粒度区间,分析原粉和不同粒度区间小麦粉的基本理化特征、流变学特性,将这些小麦粉分别制作馒头,对各馒头样品的理化性质、质构特性、微观结构和感官评价进行分析。结果显示,不同粒度区间小麦粉的理化性质和流变学特性存在显著差异(p 0. 05),破损淀粉和灰分含量随着小麦粉粒度减小逐渐增加; 180～200目区间小麦粉还有较高的粗蛋白和湿面筋含量,面筋指数也较高,此区间小麦粉馒头面团中结合水含量最高,其持水能力较强。随着小麦粉粒度减小,各粒度区间小麦粉所制作的馒头的白度逐渐升高,p H值和水分的差异对馒头品质影响不大。180～200目区间小麦粉馒头比容最高。质构分析发现,180～200目区间样品馒头的弹性表现最好,硬度和咀嚼性适中。扫描电镜观察发现,180～200目区间样品馒头面筋网状结构连续性良好,而原粉和200目以上区间样品的网状结构略差,含有大量孔洞,面筋结构松散。感官评价显示,在比容、风味和口感方面不同粒度区间样品馒头无明显差异,而180～200目区间样品综合得分最高,内部结构均匀,弹性好,风味好。综合以上结果,180～200目粒度区间小麦粉最适合制作馒头。     

文献导读

正不同粒度小麦粉对面团及馒头品质的影响研究不同粒度区间小麦粉对所制作的馒头品质的影响。利用筛分的方法将小麦粉筛分为140~160目、160~180目、180~200目、200目以上四个粒度区间,分析原粉和不同粒度区间小麦粉的基本理化特征、流变学特性,又将这些小麦粉分别制作馒头,对各馒头样品的理化性质、质构特性、微观结构和感官评价进行分析。结果显示:不同粒度区间小麦粉的理化性质和流变学特性存在显著差异(P0.05),破损淀粉和灰分含量随着小麦粉粒度减小逐渐增加;     

不同粒度区间小麦粉对挂面品质的影响

研究筛分得到的不同粒度区间小麦粉对挂面品质的影响。将小麦粉筛分为4个区间(140目~160目、160目~180目、180目~200目及200目以上)并分别制作挂面,研究不同粒度小麦粉的基本理化指标、面片结构及挂面品质。结果表明:随小麦粉粒度减小,其粗蛋白、湿面筋呈先升高后降低的趋势,而面筋指数呈现先降低后升高;小麦粉面片中蛋白质二硫键含量呈先升高后降低的趋势;观察发现(180~200)目小麦粉制作面片中面筋网络形成最佳。挂面的硬度、咀嚼性、黏附性、最佳蒸煮时间随着小麦粉粒度的减小呈下降趋势,抗弯曲性能和感官评价得分呈现先升高后降低,(180~200)目小麦粉表现最佳;表面微观观察发现小麦粉的粒度越小,挂面中淀粉与蛋白质网络结合越差。综上所述,粒度范围为(180~200)目小麦粉所制得的挂面面团中有更多的二硫键,面条中蛋白质网络结构更加均匀致密,挂面有更好的耐拉伸和抗弯性能,更适合制作挂面。     

不同粒度区间面粉对鲜湿面品质的影响

正通过筛分的方式将面粉筛分为140~160、160~180、180~200和200目以上4个不同粒度区间的面粉,并分析其对鲜湿面品质的影响。通过分析鲜湿面中二硫键和蛋白质二级结构,并分析面条的蒸煮品质、质构品质和感官品质,考察不同粒度面粉对鲜湿面品质的影响。结果表明,面粉粒度对鲜湿面品质存在较大影响,用180~200目粒度区间面粉制作的鲜     

不同粒度区间小麦粉的淀粉特征

将小麦粉筛分为不同粒度区间的小麦粉样品,研究不同粒度小麦粉中淀粉特征。分析不同粒度区间小麦粉的淀粉含量、破损淀粉、糊化特性以及A、B淀粉含量,并分析不同粒度区间小麦粉中淀粉的白度、凝胶特性以及糊化特性等。结果显示,不同粒度小麦粉中(140~160)目和(180~200)目区间内的小麦粉中淀粉含量较少,A淀粉含量随小麦粉粒度的减小而增大,B淀粉含量随小麦粉粒度的减小而减少,破损淀粉含量随小麦粉粒度的减小而增大。各粒度区间淀粉的白度随着粒度减小呈现先增后减趋势,在(160~180)目达最大值;各粒度区间淀粉中直链淀粉、支链淀粉含量、膨胀势和持水力无显著差异,(140~160)目区间内淀粉的溶解性最强,达47.92%;(140~160)目区间内小麦粉的降落数值显著高于其他区间。随着淀粉粒度的减小,淀粉凝胶的硬度、黏性、咀嚼性和回复性均有所提升,其中200目以上区间中淀粉的硬度、黏性、咀嚼性和回复性均和其他区间存在显著性差异(P0.05)。各区间淀粉糊的沉降体积存在显著性差异,其中(140~160)目区间内的淀粉沉降体积最大。随着小麦粉颗粒度的减小,小麦粉中淀粉的特性表现更好,但当小麦粉的粒度过细时,较高的破损淀粉含量又会对淀粉特性造成不利影响。     

磷酸酯双淀粉对面粉品质的影响研究

磷酸酯双淀粉是一种增稠剂,本文研究了磷酸酯双淀粉对面粉粉质、拉伸、湿面筋含量、湿面筋指数、降落数值、白度的影响。实验结果表明,在面粉中添加0~1%的磷酸酯双淀粉,面粉粉质指标、面团拉伸指标提高,面粉湿面筋含量增加,湿面筋指数增大。在面粉中添加0~2%的磷酸酯双淀粉,面粉降落数值和面粉白度增大。因此,在面粉中适量添加磷酸酯双淀粉,对面粉品质具有修饰作用。     

氧化羟丙基木薯淀粉对面粉品质的影响研究

研究了氧化羟丙基木薯淀粉对面粉粉质、拉伸、湿面筋含量、湿面筋指数、降落数值和白度的影响。结果表明,在面粉中添加0~1%的氧化羟丙基木薯淀粉,面粉粉质指标、面团拉伸指标提高,面粉湿面筋含量增加,湿面筋指数增大。在面粉中添加0~2%的氧化羟丙基木薯淀粉,面粉降落数值和面粉白度增大。综合分析,在面粉中添加1%的氧化羟丙基木薯淀粉,对面粉品质有提高作用。     

不同粒度小麦粉的理化特性研究

通过对不同研磨系统,相同研磨强度下不同粒度小麦粉的水分、灰分、白度、面筋、破损淀粉含量、粉质、拉伸特性,研究面粉粒度对面粉理化特性及流变学特性的影响。面粉在相同的研磨条件下,随着粒度的减小,其白度会增加,破损淀粉含量明显增加,吸水率随之提高,面团的流变学特性也会发生变化。而同一粒度下不同的研磨方式中,石磨的研磨强度较大,所以各方面指标也较特殊。     

直接粉碎法与回添法生产不同粒度全麦粉品质的比较研究

由超微粉碎机直接粉碎小麦和麸皮,通过激光粒度仪调控分别得到粒度为60目、80目、100目、120目的全麦粉和麸皮粉,其中,麸皮粉与小麦粉按3:7混合作为回添法生产的全麦粉,研究粒度对全麦粉品质的影响,同时对比直接粉碎法和回添法生产全麦粉的不同。结果表明:与回添法生产的全麦粉(RWWF)相比,直接粉碎法生产的全麦粉(EWWF)的湿面筋含量和降落数值更高,而水分含量、破损淀粉含量更低;EWWF面团的形成时间、稳定时间、粉质质量指数均低于RWWF面团,而弱化度及各项拉伸指标均高于RWWF面团;随着粒度的减小,EWWF白度、破损淀粉显著增大,水分含量、降落数值显著降低,灰分、湿面筋含量没有明显变化,而RWWF破损淀粉显著增大,水分含量、白度、湿面筋含量显著降低,降落数值变化不明显;2种加工方式生产的全麦粉吸水率增大,形成时间、稳定时间、粉质质量指数总体减小,弱化度变化规律不明显,其各项拉伸指标总体均先增大后减小。     

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.