脚板薯淀粉理化特性研究

采用碱法工艺提取脚板薯淀粉,并对其组成、透明度、冻融稳定性、凝沉性、持水性、溶解度、膨胀度、糊化和黏度特性等理化性质进行了分析。结果表明:脚板薯直链淀粉含量为27.05%,淀粉透明度、凝沉性、持水力、热稳定性较好,但冻融稳定性差,不易糊化,脚板薯淀粉的溶解力和膨润力随着温度的升高而增大,与水之间的相互作用较强。     

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。     

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。     

黑龙江省主栽小米淀粉特性分析

为研究黑龙江省主栽小米淀粉的特性,利用冰箱反复冻融法、紫外分光光度等方法,对6种小米淀粉的功能性质进行了测定及分析。结果表明:吨谷1号淀粉的溶解度、膨胀度和透明度最高,分别为10.36%±0.06%、18.24%±0.27%和3.58±0.23。朝新谷8号淀粉的凝沉性最高,冻融稳定性最差。直链淀粉含量与溶解度、膨胀度、冻融稳定性和透明度呈负相关;与凝沉性呈正相关。支链淀粉含量与溶解度、膨胀度和凝沉性呈正相关,与冻融稳定性呈负相关。淀粉的支直比与溶解度、膨胀度、冻融稳定性和透明度呈正相关,与凝沉性呈负相关。本研究为小米及其淀粉的深加工利用提供参考。     

茶叶籽淀粉理化性质研究

研究茶叶籽淀粉颗粒形貌、大小和糊化温度,测定其溶解度和膨胀度、透明度、冻融稳定性、凝沉性及黏度等理化性质,并与玉米淀粉进行比较。结果表明：茶叶籽淀粉颗粒表面光滑,呈椭圆形或球形;不易发生糊化;溶解度与膨胀度随温度变化程度不大;与玉米淀粉相比,透明度与冻融稳定性不及玉米淀粉糊,但抗老化性稍强,黏度也高于玉米淀粉。     

山西不同品种谷子淀粉的理化特性研究

从谷子主产区山西省选取8个具有代表性的谷子栽培品种作为供试材料,分析研究了其淀粉的颗粒形态及粒径大小、直链淀粉含量、碘蓝值与淀粉糊的透光率、冻融稳定性、糊化特性、溶解度与膨胀度及凝沉特性等理化性状。结果表明：小米淀粉颗粒均为单粒,外形规整,多数为多角形,少数为卵圆形,具有清晰可见的偏光十字,不同品种间淀粉颗粒形态差异明显。小米淀粉小颗粒的粒径为0.42~2.25 μm,大颗粒的粒径为3.42~29.26 μm,小米淀粉的粒径分布特征呈现出“三峰”型。8个品种的直链淀粉含量变幅为2.22~17.96%,碘蓝值变幅为0.586~0.872,透光率变幅为2.4~29.2%,析水率变幅为3.67~49.85%,糊化温度变幅为67.6~78.8 ℃,各品种间具有显著差异。此外,各品种淀粉的糊化特性、溶解度、膨胀势及淀粉糊的凝沉特性也有着明显的差异。因此,应根据不同的加工目的采用相适宜的品种。     

不同物理方法处理对碎米中淀粉特性的影响

采用挤压、微波、超声波三种物理方法对水分含量18%的碎米淀粉进行处理,研究分析碎米淀粉经物理方法处理前后的理化性质和结构变化。结果表明,碎米淀粉经微波和超声处理后酶解力增加,糊化黏度下降,而溶解度、膨胀力、糊化温度和直链淀粉含量变化不显著;两种淀粉颗粒表面棱角减少,淀粉颗粒晶型基本没有发生变化,淀粉结晶区降低。挤压后的碎米淀粉变化较大,颗粒形状为片状,凝沉性强,1.0 h后体积仅为3 mL,糊化温度明显降低至55.0 ℃,直链淀粉含量增长为30.75%,溶解度强,为0.59%,酶解力达到45%,X-射线主要衍射峰的强度降低。     

黑米淀粉理化性质分析

通过与普通大米淀粉的性质比较,对黑米淀粉的溶解度、膨润力、凝沉稳定性和冻融稳定性等理化性质进行了深入研究。结果表明:黑米淀粉颗粒属于多角形,粒径较小。当温度达到60℃时,黑米淀粉糊化速度迅速增加,淀粉结构被破坏。当温度达到55℃时,黑米淀粉比大米淀粉具备更优良的膨润力和溶解度。黑米淀粉的凝沉稳定性、冻融稳定性不如大米淀粉,不同浓度的电解质(氯化钠)和非电解质(蔗糖)存在时,其冻融稳定性会增大。     

板栗贮藏前后淀粉性质的比较

为研究板栗贮藏前后淀粉性质的变化,分别测定淀粉的凝沉性、冻融稳定性、透光率、结晶结构、直链与支链淀粉含量、粒度、糊化特性等。结果表明,贮藏后的板栗淀粉较贮藏前其淀粉糊的凝沉加快;冻融稳定性、透明度下降;淀粉颗粒结晶结构未发生变化,仍属于C型;糊化温度降低,峰值黏度上升,稳定性变差,更容易老化。贮藏后板栗淀粉的抗老化能力降低。     

菠萝蜜种子淀粉颗粒性质的研究

以菠萝蜜种子为原料,提取并纯化菠萝蜜种子淀粉,对菠萝蜜种子淀粉的颗粒形貌、X-光衍射图样、直链和支链淀粉含量、溶解度和膨胀度、淀粉糊的冻融稳定性等特性进行了研究。结果表明:菠萝蜜种子淀粉颗粒的大小为5～25μm,平均粒径为15μm,多呈半球形和球形,具典型的偏光十字;淀粉颗粒的晶体结构属C型;用偏十字消光法测定淀粉糊化温度,糊化起始、终止温度分别为68.2、78.3℃;该淀粉的直、支链淀粉分别为24.2%、75.8%;菠萝蜜种子淀粉的溶解度和膨胀度不同于玉米和马铃薯淀粉,其膨胀度在76℃以后迅速增加并大于玉米淀粉,更相似于马铃薯淀粉。     

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.