干燥方法对颗粒状冷水可溶性淀粉性能的影响

以马铃薯淀粉为原料,在乙醇-碱法的基础上采用热辐射烘燥法和真空冷冻干燥法制备颗粒状冷水可溶性淀粉(GCWS),比较分析2种烘燥方法制备的GCWS淀粉的理化性能,包括双折射现象分析、颗粒样貌分析、傅里叶红外光谱分析、冷水溶解度、热特性分析和糊化性能分析等。结果表明,乙醇-碱法可以充分破坏马铃薯淀粉的结晶结构,但无新的基团生成,干燥方法对GCWS淀粉样貌影响较大,真空冷冻干燥法制备的GCWS马铃薯淀粉的冷水溶解度略低于热辐射烘燥制备的GCWS马铃薯淀粉。RVA衰减黏度数据表明热辐射烘燥的GCWS马铃薯淀粉热稳定较好,而回生黏度数据表明真空冷冻干燥制备的GCWS马铃薯淀粉抗凝沉性较好,不易老化。     

颗粒状冷水可溶马铃薯淀粉的制备及性质研究

以马铃薯淀粉为原料,研究了常压下颗粒状冷水可溶淀粉的制备方法和性质特征。实验证明,醇解法所得的颗粒状冷水可溶淀粉的溶解度可以达到100%。反应的最佳条件为相对加入碱量28mL,乙醇浓度80%,淀粉乳浓度14%,反应温度40℃,反应时间50min,对应的最佳颗粒状冷水可溶马铃薯淀粉的冷水溶解度为97.4%(60g马铃薯淀粉)。经醇解法处理后所得到的不同冷水溶解度的颗粒状淀粉样品,颗粒保持完整,但其表面不再光滑,呈现出凹陷﹑空隙和裂缝等特征;随着冷水溶解度的提高,淀粉样品的偏光十字呈现逐渐减少的趋势,且结晶性逐渐降低直至完全消失。     

基于硫脲复合溶剂体系制备再生冷水可溶性淀粉

采用硫脲复合溶剂体系溶解马铃薯淀粉(PS),通过水提醇沉法分离提纯后,烘箱干燥制备再生冷水可溶性淀粉(RCWSS-T)。结果表明:硫脲复合溶剂体系所得的RCWSS-T冷水溶解度达到43.50%;FTIR分析表明该体系制备RCWSS-T过程中没有新的化学键生成;XRD结果表明PS的晶体结构由最初的双螺旋B型变为RCWSS-T的单螺旋V型;SEM分析表明其颗粒尺寸明显减小。与尿素复合溶剂体系相比,硫脲复合溶剂体系下所得RCWSS-T的冷水溶解度更低,其原因可能是硫脲削弱淀粉分子间及分子内氢键的能力不如尿素,与淀粉形成氢键的稳定性也不如尿素。     

小麦颗粒状冷水可溶淀粉的制备工艺条件优化

以小麦A淀粉为材料.采用乙醇-碱处理法制备颗粒状冷水可溶淀粉,在系统分析乙醇体积分数、碱浓度、反应温度、反应时间等因素对颗粒状冷水可溶淀粉溶解度影响的基础上,对其制备工艺条件进行了优化.结果表明:采用乙醇-碱法制备小麦颗粒状冷水可溶淀粉,乙醇体积分数和反应时间对产物溶解度的影响显著;小麦颗粒状冷水可溶淀粉的适宜制备条件为反应温度65℃,乙醇体积分数80%,反应时间为80 min,碱浓度10 g/100 ml,其溶解度可达81.44%.     

冷水可溶性淀粉制备方法研究进展

冷水可溶性淀粉是指采用物理或化学方法将原淀粉进行变性处理而得到的一种可在冷水中溶解成糊的变性淀粉。冷溶淀粉因其广泛的应用领域,已成为近年来变性淀粉中研究的热点。主要介绍了冷溶淀粉的种类及其制备方法,包括预糊化淀粉、颗粒状冷水可溶性淀粉以及化学变性的冷水可溶性淀粉,重点介绍了近年来发展迅速的颗粒状冷水可溶性淀粉的制备工艺,旨在为冷溶淀粉的开发利用提供科学的理论依据。     

复合酶法制备马铃薯抗性淀粉工艺研究

以马铃薯淀粉为原料，采用α-淀粉酶和普鲁兰酶相结合处理的方式制备马铃薯抗性淀粉，通过单因素试验分别考察了α-淀粉酶和普鲁兰酶的pH值、反应温度、反应时间、酶添加量对抗性淀粉(RS)得率的影响；进而采用Box-Behnken设计法对复合酶法制备马铃薯抗性淀粉的工艺参数进行优化；最终，采用Englyst法对马铃薯抗性淀粉消化性进行分析。结果表明，制备马铃薯抗性淀粉的最佳工艺条件为：α-淀粉酶，pH6.5、反应温度70℃、反应时间15 min、酶用量4 U/g；普鲁兰酶，pH值5.0、反应温度60℃、反应时间24 h、酶用量8 U/mL。此条件下，马铃薯抗性淀粉得率为(44.48±1.37)%。马铃薯淀粉经α-淀粉酶与普鲁兰酶联合处理后，不仅提高了其抗消化性，还使抗性淀粉(RS)得率显著提高，同时将马铃薯淀粉中快消化淀粉(RDS)降低至21.23%，而慢消化淀粉(SDS)增加至36.32%。该研究为后续马铃薯深加工及慢消化型食品开发提供一定的理论参考。     

超声波辅助制备冷水可溶性甘薯淀粉

以甘薯淀粉为原料,采用超声波辅助乙醇碱法制备颗粒状冷水可溶性甘薯淀粉,系统研究了淀粉乳浓度、乙醇浓度、碱用量、超声波功率和超声波时间对冷水可溶淀粉溶解度的影响。在单因素试验基础上,通过Box-Behnken响应面优化制备条件,得到最佳的反应条件为:淀粉乳质量浓度4.0 g/100 m L,乙醇体积分数81%,超声波功率为300 W,超声时间22 min。经验证,在最佳条件下,所制得的甘薯淀粉溶解度达到96.38%,回归模型预测值与实测值的相对误差1%。研究结果表明,超声波在制备冷水可溶性甘薯淀粉方面有一定的应用前景。     

颗粒状冷水可溶性淀粉研究进展

颗粒状冷水可溶性淀粉是经化学试剂处理进行物理变性生产的，概述了几种制备颗粒状冷水可溶性淀粉的方法和生产工艺，介绍了颗粒状冷水可溶性淀粉的各种特性及其应用，阐明了颗粒状冷水可溶性淀粉的广阔的发展前景。     

三种淀粉载体粉末酱油的性质对比研究

通过真空冷冻干燥技术制备粉末酱油,分别以原淀粉、多孔淀粉和颗粒状冷水可溶性多孔(GCWSM)淀粉作为载体,以淀粉的冷水溶解度、粘度、水解率及柠檬黄吸附量等性质和酱油的氨基态氮含量为评价指标,通过感官评定实验,确定制备粉末酱油的最适载体。使用差示量热扫描仪(DSC)研究粉末酱油制备过程中热力学特性的变化,结果表明:GCWSM淀粉的冷水溶解度和粘度分别为46.79%和205.8mPa·s,水解率和柠檬黄吸附量分别为32.7%和2.417mg/g;GCWSM淀粉制备的粉末酱油的氨基态氮含量达到0.487g/100mL;感官评定表明三种淀粉载体粉末酱油无显著性差异,GCWSM淀粉可以代替原淀粉和多孔淀粉制备粉末酱油;DSC结果显示粉末酱油中的GCWSM淀粉减弱了淀粉本身的糊化特性。     

冷水可溶甘薯淀粉的制备及性能

以甘薯淀粉为原料,采用乙醇-碱法对冷水可溶甘薯淀粉(CWS)的制备进行了研究,优化了制备冷水可溶甘薯淀粉的工艺条件,并对冷水可溶甘薯淀粉的黏度特性、凝沉性和透明度进行了测定.结果表明,冷水可溶甘薯淀粉的最佳制备工艺条件为:乙醇体积分数80％,料液比为1∶5(g/mL),氢氧化钠溶液(3mol/L)加入量为30mL,反应温度35℃.在最佳条件下,冷水可溶甘薯淀粉的溶解度可高达87.92％.扫描电镜观察表明,冷水可溶甘薯淀粉颗粒表面有较大的凹陷和一些孔洞并且发生黏连,使其具有较好溶解性和粘性,并且其糊的凝沉性、抗剪切稳定性加强,但透明度有所降低.     

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.     

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.     

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.     

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.