荞麦分离蛋白-葡聚糖共价复合物的制备

以荞麦蛋白为原料,在大分子拥挤条件下,采用湿法制备荞麦蛋白-葡聚糖共价复合物。选择60℃和70℃为反应温度,研究了不同反应条件对共价复合物溶解性、乳化性的影响,并通过游离氨基以及褐变程度来控制反应进程。结果表明,荞麦蛋白与葡聚糖在70℃反应6 h后,其乳化性得到明显改善。SDS-PAGE电泳(考马斯亮蓝染色和糖蛋白染色)验证了共价复合物的生成。DSC分析结果表明共价复合后荞麦蛋白的热稳定性得到提高。荧光光谱表明共价复合物的蛋白质极性降低,疏水性增强。     

大豆分离蛋白-葡聚糖糖基化产物作为乳化剂和活性物质载体的性能分析

研究大豆分离蛋白(soy protein isolate,SPI)-葡聚糖共价接枝物的制备及其乳化性质和作为姜黄素载体的性能。在95℃的"大分子拥挤"体系条件下,2种大分子通过美拉德反应进行共价接枝。根据糖基化产物在SPI等电点附近(p H 4.5)和中性(p H 6.5)条件下的溶解性将其分成2个组分,分别为MC45和MC65,并对其性能表征分析。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和分子质量测定分析显示,反应后生成大分子质量的接枝物。MC45制备的乳液在酸性环境中的粒度低于MC65,其平均粒径约为10μm,并且受离子浓度和温度的影响较小。与天然蛋白、SPI-葡聚糖混合物及MC45相比,荷载量、1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率分析表明MC65组分具有更好的姜黄素运载性能,MC65组分制备的姜黄素纳米颗粒荷载量为30.21μg/mg,DPPH自由基清除率为18.33%,其粒径最大。     

大分子拥挤体系中SPI-葡聚糖共价复合物制备

通过大分子拥挤体系发生Maillard反应制备大豆蛋白-葡聚糖共价复合物,系统研究了不同反应条件对制备产物的影响,得出最佳条件为:pH6.5的磷酸盐缓冲液中,反应物总浓度为40％,60℃反应30h,SPI与葡聚糖共价接枝效果最好,表现出了优越的乳化性质.采用十二烷基磺酸钠聚丙烯酰胺凝胶电泳法(SDS-PAGE)证实了大豆分离蛋白与葡聚糖之间发生共价结合,产生了共价复合物.该方法制备的产物色泽良好,褐变颜色较少,反应时间大大缩短,只需30h即可完成,而传统的干热制备反应一般需要几天或者数周才能完成.该实验模拟大分子拥挤环境,将多糖和蛋白质作为生物大分子处于该环境中,得到的产物大豆蛋白-葡聚糖共价复合物,可作为一种“绿色”乳化剂,可广泛应用到食品工业中.     

大分子拥挤环境下大豆7S球蛋白糖基化研究

生命科学领域中的大分子拥挤环境作为反应介质进行Maillard反应制备大豆7S球蛋白-葡聚糖共价复合物。对液相体系中发生Maillard反应的各种影响因素进行系统研究,并采用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)技术证实大豆7S球蛋白和葡聚糖发生了共价结合,得出共价复合物制备的最优条件。结果表明:5%的7S球蛋白与15%的葡聚糖在pH7.0条件下,95℃反应6h后,形成了良好的大分子共价复合物。产物色泽良好,褐变程度较低,反应时间大大缩短。     

绿豆分离蛋白的葡聚糖糖基化改性研究

为改善绿豆分离蛋白(MBPI)的理化特性,利用葡聚糖(Dextran)接枝改性MBPI,并对改性后蛋白的溶解性、乳化特性、表面疏水性、亚基结构的变化进行研究。SDS-PAGE凝胶电泳分析结果表明,MBPI和Dextran接枝反应后生成了分子量较大的共价复合物,表面疏水性分析表明,相比于未处理蛋白,MBPI-Dextran共价复合物的表面疏水性含量降低,溶解性和乳化特性的研究表明,改性后的蛋白质溶解性和乳化特性得到不同程度的改善。     

大豆分离蛋白-单宁酸-多糖三元复合物的功能特性及结构表征

为了探究单宁酸(tannin acid,TA)、麦芽糊精(maltodextrin,MD)、聚葡萄糖(polydextrose,PD)共价修饰对大豆分离蛋白(soybean protein isolate,SPI)功能特性和结构的影响,采用碱处理法和湿法美拉德反应将TA、MD、PD共价接枝到SPI上,分别得到二元共价复合物(SPI-TA)和2种三元共价复合物(SPI-TA-MD、SPI-TA-PD)。通过十二烷基磺酸钠-聚丙烯酰胺凝胶电泳和反应基团的测定研究SPI-TA、SPI-TA-MD、SPI-TA-PD复合物中共价键的形成以及共价接枝程度。采用紫外吸收光谱和傅里叶变换红外光谱法研究二元、三元共价复合物中SPI结构的变化。通过溶解性、乳化性、起泡性、抗氧化活性、热稳定性和表面疏水性等指标,研究TA、MD、PD的共价接枝对SPI功能性质的影响。结果表明:TA、MD、PD与SPI共价结合改变了SPI的结构,降低SPI二级结构中β-折叠含量；TA接枝当量为(35.56±1.32)μmol/g,MD的接枝度为46.54%,PD的接枝度为32.26%；相比于SPI,SPI-TA-MD、SPI-TA-PD三元共价复合物的溶解性、乳化性、抗氧化活性、起泡性、表面疏水性和热稳定性都显著提高(P<0.05)。研究结果旨在为改善SPI的功能特性和深入了解SPI的改性机制提供理论依据,以期为食品功能因子传递系统,尤其是松籽油乳液传递系统提供新的食品级原料。     

干法糖基化改性提高大豆分离蛋白的乳化性

在干热条件下,大豆分离蛋白与葡聚糖两种大分子通过Maillard反应进行共价键合,以共价物的乳化活性为指标,确定影响糖基化蛋白乳化活性的因素依次为:反应温度＞反应时间＞pH＞底物配比,最佳工艺条件为:反应温度70℃,反应时间24 h,糖-蛋白(2:1),pH 8.0.以共价物的乳化稳定性为指标,确定了影响糖基化蛋白乳化稳定性的因素依次为:底物配比＞反应时间＞反应温度＞pH.最佳工艺条件为:糖-蛋白(3:1),反应时间24 h,反应温度70℃,pH8.0.通过聚丙烯酰胺凝胶电泳验证了大豆分离蛋白与葡聚糖发生了接枝反应.     

大豆分离蛋白与单糖、双糖、多糖共价复合物的冻融特性及结构表征

研究糖种类对大豆分离蛋白(soybean protein isolate,SPI)-糖共价复合物冻融特性的影响,以改性产物的乳化性质和乳析指数为指标,研究SPI与葡萄糖(glucose,G)、麦芽糖(maltose,M)和葡聚糖(dextran,D)共价复合产物冻融特性的变化,并分析改性产物的出油率、接枝度、傅里叶变换红外光谱、荧光光谱变化情况。结果表明,在反应温度80℃、反应时间3 h、蛋白质量分数4%、SPI与M质量比4∶1的条件下,SPI-麦芽糖共价复合物(SPI-M)的乳化活性和乳化稳定性分别是对照样品的1.41倍和1.29倍,经过3次冻融循环后,乳析指数分别降低了29.68%、28.3%、29.57%,出油率分别降低了4.8%、16.8%、22.6%,SPI-M的冻融稳定性显著提高,且SPI-M的乳化性和冻融稳定性均好于SPI-葡萄糖共价复合物(SPI-G)和SPI-葡聚糖共价复合物(SPI-D)。接枝度分析表明SPI-M的接枝度明显高于SPI-G和SPI-D的接枝度;傅里叶变换红外光谱分析表明糖分子以共价键的形式接入到SPI分子中;荧光分析表明蛋白结构发生改变。     

挤压大米蛋白-葡聚糖接枝复合物的功能性质及结构表征

为了研究挤压和糖接枝改性的方法对大米蛋白功能性及结构的变化的影响,本文研究了不同挤压条件下挤压的大米蛋白与葡聚糖的糖接枝反应,分析了不同挤压改性的大米蛋白对糖接枝反应接枝度的影响,根据单因素试验优化反应条件,在挤压温度90℃、大米蛋白水分含量35%,螺杆转速200 r/min的条件下挤压的大米蛋白与葡聚糖接枝得到的复合物,接枝度最大为(17.6±0.3)%,试验测定接枝度为(17.6±0.3)%共聚物的溶解性和乳化性及表面疏水性。结果表明,与天然大米蛋白相比,挤压的大米蛋白与葡聚糖接枝复合物的溶解性在较宽的范围内显著增加,增加了8.4%~76.6%,乳化性和乳化稳定性分别增加了62.2%和73.9%,表面疏水性降低了69.5%。同时,试验通过傅里叶红外光谱、SDS-PAGE电泳、扫描电镜等方法和手段分析了大米蛋白亚基结构及表面结构特征。结果表明,挤压糖接枝反应显著改变了蛋白亚基结构,α-螺旋、β-转角和无规卷曲结构含量分别增加了24.4%、26.0%和19.9%,而β-折叠结构含量减少了15.0%,SDS电泳分析结果显示挤压后大米蛋白与葡聚糖接枝反应物的条带51.0 ku和80 ku~82 ku亚基带变得模糊,并且在分离胶和浓缩胶分理处出现大分子量分子,说明有共价连接大分量聚集物生成,扫描电镜分析了表观结构变化,表明挤压和糖接枝对蛋白结构改变显著。     

大豆分离蛋白-多糖美拉德反应共聚物的制备及性能研究

以大豆分离蛋白(SPI)和海藻酸钠、壳聚糖、葡聚糖利用干法美拉德反应制备大豆分离蛋白-多糖共聚物,通过比较反应产物的接枝度、乳化活性和乳化稳定性,选取大豆分离蛋白-海藻酸钠共聚物,并对其制备条件进行研究。在单因素实验的基础上,以接枝度、乳化活性和乳化稳定性为评价指标,通过正交实验,确定大豆分离蛋白-海藻酸钠共聚物最佳制备条件为:糖蛋白比9:10,反应温度为68℃,反应时间24 h;最终得到共聚物的接枝度为27.2%,乳化活性提高了121%,乳化稳定性提高了255%。     

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.     

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.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.