夏谷区主栽谷子品种淀粉理化特性研究

从夏谷区主栽品种中选取9个谷子品种作为供试材料,对其淀粉的颗粒形态及大小、化学组成、碘蓝值、透光率、冻融稳定性、糊化特性、溶解度与膨胀势及凝沉特性等理化性质进行系统研究。结果表明：小米淀粉颗粒均为单粒,由0.48～2.25μm与3.50～29.32μm两种不同粒径范围的颗粒组成,多呈多角形,少数呈卵圆形,具有清晰可见的偏光十字,品种间淀粉颗粒形态差异明显。直链淀粉含量为2.91%～15.80%,碘蓝值为0.601～0.809,透光率为4.4%～22.3%,析水率为0.77%～62.23%,品种间差异显著。不同品种小米淀粉的糊化特性、溶解度与膨胀势及淀粉糊的凝沉特性也有着明显的差异。因此,可根据不同的加工目的选择不同的谷子品种。     

我国不同地区特色品种小米淀粉性质

选取10 个不同地区、品种的特色小米作为研究对象,采用0.2 g/100 mL的NaOH溶液与1 g/100 mL的十二烷基硫酸钠溶液复合法提取小米淀粉,并对其基本成分、颗粒形态、黏度、透光率、溶解度和膨胀度等进行研究。结果表明：小米淀粉的直链淀粉含量为12.10%,平均粒径为6.49 μm,糊化温度为68.9～72.3 ℃。不同地区、品种的小米淀粉的直链淀粉、溶解度、峰值黏度、崩解值和老化值存在较大差异。     

山西省不同品种谷子淀粉理化性质的比较

以山西省13种不同谷子品种作为供试材料,采用酶法制备淀粉,对其溶解度、膨胀度、透光率、冻融稳定性、凝沉性、热特性及结晶结构进行研究,比较其差异性。结果表明:13种谷子淀粉的溶解度及膨胀度范围分别为10.79%~19.11%,25.11%~42.91%,其中2-T9膨胀度最大,2-T3的溶解度最大,品种之间存在显著性差异;透光率为6.278%~19.39%,析水率为7.08%~60.73%,黄谷的透光率和析水率都是最高;凝沉性试验同样表明黄谷的稳定性显著优于其他品种;采用差示扫描量热仪(DSC)测定谷子淀粉的热特性,糊化起始温度、峰值温度、最终温度和相变热焓分别为52.78~70.95℃,71.12~79.26℃,80.42~88.48℃,9.83~11.87J/g,这些特性品种间差异显著;X-射线衍射分析表明13种谷子淀粉的结晶结构属于A型。     

怀山药淀粉性质研究

以怀山药为原料,采用石灰水浸泡工艺提取怀山药淀粉,对怀山药淀粉的颗粒形貌、偏光十字、溶解度、膨胀度、透明度、凝沉性、糊化温度、直链淀粉和支链淀粉含量进行了研究,结果表明:怀山药淀粉的颗粒外形大都是圆形或者椭圆形,偏光十字比较明显;怀山药淀粉的溶解度、膨胀度、透明度比玉米淀粉高,比马铃薯淀粉低;怀山药淀粉糊的凝沉较快;怀山药淀粉的糊化温度为61~75℃,不易糊化;怀山药淀粉的直链淀粉含量为24.18%;淀粉乳浓度、温度、pH对怀山药淀粉的黏度都有影响,怀山药淀粉抗碱能力较强。     

青稞淀粉理化特性的研究

研究了4种青稞淀粉(林周148、北青6号、昆仑6号、藏青320)的理化特性,研究发现:不同品种的青稞淀粉在基本组分上存在差异,淀粉颗粒的平均粒径在17.49~18.13μm之间;青稞淀粉糊的透明度随着放置时间的延长而减小;溶解度和膨胀力都随着温度的升高而增大,总体上,青稞淀粉的溶解度与直链淀粉含量呈正相关性,膨胀力与直链淀粉含量呈负相关性,淀粉糊的溶解度和膨胀力还受到淀粉颗粒大小的制约;青稞淀粉糊的冻融稳定性与直链淀粉含量呈负相关性;青稞淀粉的峰值黏度与溶解度呈负相关性,糊化温度与膨胀力呈负相关性。在液化后,青稞淀粉的DE值在17.55~19.33之间;糖化后,DE值在80.04~90.14之间;青稞淀粉酶解后DE值存在差异与淀粉颗粒大小分布和破损淀粉含量有关。     

青稞淀粉和小麦淀粉的理化性质比较研究

研究了青稞淀粉的理化性质,包括淀粉的颗粒形态、粒度分布及淀粉糊透明度、溶解度、膨胀力和糊化特性,并与小麦淀粉性质进行比较。结果表明:青稞淀粉颗粒的平均粒径大于小麦淀粉颗粒的平均粒径,青稞淀粉颗粒大小和形状分布均匀;青稞淀粉糊透明度大于小麦淀粉糊,但在储藏过程中,青稞淀粉糊透光率变化显著;青稞淀粉的溶解度和膨胀力均大于小麦淀粉糊,这与小麦淀粉中小颗粒淀粉含量较多有关;与小麦淀粉的糊化相比,青稞淀粉成糊温度低,糊化容易,但峰值黏度低,衰减值大,热糊稳定性差,回生值大,冷糊稳定性差,易老化。     

马铃薯淀粉的物化性质研究

研究马铃薯淀粉的组成、颗粒形貌、粒径大小及溶解度与膨润力、透明度、凝沉性、糊化方面的性质,并与绿豆、玉米淀粉进行比较.结果表明,马铃薯淀粉的蛋白质含量为0.27%, 直链淀粉含量为20.4%,颗粒为椭圆形,平均粒径为40 μm;马铃薯淀粉的溶解度与膨润力较高;马铃薯淀粉的透明度为66.8%,凝沉性高于豆类淀粉,峰值黏度为2 000 BU.     

糜子淀粉理化性质的分析

为掌握陕西省主要糜子品种的淀粉理化性质,以陕北地区3个主要糜子品种为材料,研究了糜子淀粉的颗粒结构、糊化特性、糊特性以及凝胶质构特性.结果表明:糜子淀粉颗粒为多角形或球形,粒径为1.9～10.0μm,偏光十字较为明显,微晶结构为A型;3个糜子品种的直链淀粉含量为2.85%～19.30%,碘蓝值较高;糜子淀粉的热糊稳定性、冷糊稳定性优于马铃薯淀粉,酸、碱对糜子淀粉糊黏度性质的影响较大,在碱性(pH 10.0)条件下,糜子淀粉起始糊化温度的升高幅度大,冷糊稳定性更强.糜子淀粉糊的透明度较低,冻融稳定性和凝胶形成能力较差,凝沉顺序依次为榆糜1号淀粉>榆糜2号淀粉和玉米淀粉>YM0506淀粉和马铃薯淀粉.榆糜2号淀粉凝胶的硬度较高,回弹性和黏聚性均低于玉米淀粉和马铃薯淀粉.     

蚕豆、豌豆淀粉特性研究

本文以蚕豆、豌豆为对象,研究了两种豆类淀粉的各种性质:总淀粉含量,直链淀粉含量,淀粉的糊化特性,淀粉糊的膨胀度和溶解度,淀粉-碘复合物的可见光谱,淀粉糊的透明度,冻融稳定性,凝沉性以及沉降体积。结果表明:通过对淀粉的溶解度、膨胀度、黏度等性质进行研究,对蚕豆和豌豆淀粉性质有了初步的了解。实验发现温度和放置时间对两种豆类淀粉的性质有不同程度的影响。两种淀粉在进行加热、糊化时,随着温度的变化,都将不同程度地影响粉糊的溶解度和膨胀度等。两种淀粉的膨胀度和溶解度均随温度的升高而增加。放置的时间的不同,对淀粉糊的沉降体积、透明度等性质有不同程度的影响。并且淀粉碘复合物可见光光谱的最大吸收波长均在620 nm左右。     

肇实淀粉理化特性的研究

对肇实淀粉的颗粒形貌、X-射线衍射谱图、直链与支链淀粉含量、糊化温度、溶解度与膨胀度以及糊的透明度、冻融稳定性、凝沉性进行了研究,并与玉米淀粉进行了比较,为肇实淀粉的应用提供了一定的理论基础。     

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.