化学发光法对荞麦发芽前后酚类物质抗氧化活性的评价

采用化学发光法测定了在发芽前后中荞麦中酚类物质的抗氧化活性,并对其进行了比较。结果表明:荞麦和发芽荞麦中的酚类物质在不同的发光体系中均表现出良好的抗氧化活性,其清除超氧阴离子自由基的IC_(50)值分别为0.695、0.433 mg/mL;清除羟自由基的IC_(50)值分别为6.25、4.13μg/mL;清除H_2O_2的IC_(50)值分别为9.80、7.13μg/mL。通过比较,得出荞麦经发芽后其抗氧化活性优于未经发芽处理的荞麦,这可能与荞麦经发芽后释放出了一些结合态的酚类物质有关。     

菠萝蜜果皮多酚提取工艺及其抗氧化和酪氨酸酶抑制作用研究

目的:探究各单因素对菠萝蜜果皮多酚得率的影响以及菠萝蜜果皮多酚的抗氧化和酪氨酸酶抑制作用。方法:在单因素试验的基础上运用Box-behnken中心组合试验对菠萝蜜果皮多酚超声波提取工艺进行优化,并测定多酚提取物对DPPH自由基的清除率和对酪氨酸酶活性的抑制率。结果:在乙醇体积分数66%、提取温度41℃、液料比27:1(mL/g)的条件下,菠萝蜜果皮多酚得率为2.24%,与理论预测值相近。多酚质量浓度为0.2 mg/mL时,对DPPH自由基的清除率达75%。菠萝蜜果皮多酚浓度与酪氨酸酶活性抑制率存在显著相关性(P0.01),相关系数为0.972;抑制酪氨酸酶活性的IC_(50)值为158.85μg/mL,对照品曲酸的IC_(50)值为18.97μg/mL。结论:菠萝蜜果皮多酚有良好的抗氧化活性和酪氨酸酶抑制活性,具有美白产品研发价值。     

紫金蜜桑叶活性成分的提取工艺优化及其抗氧化能力评价

本文以紫金蜜桑叶为研究对象,采用超声波辅助乙醇同时提取紫金蜜桑叶活性成分(多酚、黄酮和多糖),并制备桑叶提取物。以3种活性成分含量为考察指标,通过单因素试验考察乙醇浓度、料液比、提取温度和提取时间对活性成分提取效果的影响,在此基础上进行正交试验以优化得到最佳提取工艺,并对桑叶提取物的抗氧化能力进行探究。结果表明,紫金蜜桑叶活性成分的最佳提取工艺条件为乙醇浓度60%、料液比1:35 g/mL、提取温度45℃、提取时间70 min。在此条件下,紫金蜜桑叶活性成分的提取率高达20.49%,其中,多酚、黄酮和多糖的平均含量分别为12.13 mg/g、1.79 mg/g和58.74 mg/g。所得桑叶提取物对DPPH自由基、羟自由基以及超氧阴离子自由基的半数清除率(IC_(50))分别为0.06 mg/mL、3.13 mg/mL和1.15 mg/mL。由此可见,紫金蜜桑叶提取物具有较强的抗氧化能力。     

山楂叶多酚的纯化及其抗氧化特性与组分分析

探讨山楂叶多酚的纯化工艺,并分析其抗氧化活性和组成成分。比较SP-825,D101,AB-8,XDA-2等四种树脂对山楂叶多酚的吸附性能,筛选最佳树脂,并优化其纯化参数,分析其抗氧化活性、组成成分和红外光谱特性。结果表明,4种树脂中AB-8树脂纯化山楂叶多酚效果较好,其最佳纯化参数为样液初始pH 4.5、初始质量浓度0.064 mg/mL、上样流速1.5 mL/min、洗脱剂乙醇体积分数为70%和洗脱流速为0.6 mL/min,在此条件下,山楂叶多酚的回收率为78.25%,纯化后多酚的纯度提高了4.15倍。山楂叶多酚具有较好的抗氧化能力,其粗提液和纯化液清除DPPH·的IC_(50)值分别为(1.28±0.14)和(0.78±0.09)对螯合Fe~(2+)的IC_(50)值分别为(55.58±1.24)和(34.13±1.02)总还原能力的IC_(50)值分别为(3.66±0.18)μg/mL和(2.12±0.23)μg/mL,纯化液清除·OH的IC_(50)值为(4.49±0.16)μg/mL;表明纯化后其抗氧化能力有显著提高。FTIR分析表明其具有多酚和黄酮的特征峰;HPLC分析表明山楂叶多酚主要含绿原酸、表儿茶素、阿魏酸、芦丁和熊果酸,说明山楂叶多酚具有较高的开发应用价值。     

青砖茶清除DPPH·能力及其多酚和黄酮含量研究

采用DPPH自由基(DPPH·)清除法测定了18个青砖茶样品的抗氧化活性,并按照GB/T 8313-2008《茶叶中茶多酚和儿茶素类含量的检测方法》方法和亚硝酸钠-硝酸铝比色法分别测定它们的多酚和黄酮含量。结果表明:18个青砖茶水提取物均能清除DPPH·,具有抗氧化活性,它们的浓度(0.05 mg/mL~0.30 mg/mL)与DPPH·清除率之间具有良好的线性关系,二者的相关系数介于0.974 2~0.994 5,且清除DPPH·的IC_(50)最大值为0.258 6 mg/mL,最小值为0.114 4 mg/mL;多酚和黄酮含量的最高值分别为3.57%和3.84%,最低值分别为2.06%和1.01%;青砖茶清除DPPH·的IC_(50)与多酚和黄酮含量的相关系数分别为0.684和0.715。     

山楂叶多酚的酶法提取及抗氧化活性研究

实验研究酶法提取山楂叶多酚的工艺条件,并对山楂叶多酚的体外抗氧化活性进行了探讨。结果表明,使用纤维素酶和果胶酶质量比为1:1的复合酶,其质量浓度为0.20 mg/mL时,在酶解pH4.5、酶解温度45℃下酶解120 min时多酚提取得率最大,为0.56%。体外抗氧化实验结果表明,山楂叶粗多酚具有较好的总还原能力,其清除DPPH自由基的IC_(50)值为1.02μg/mL,螯合Fe~(2+)的IC_(50)值为55.62μg/mL,清除羟自由基的IC_(50)值为11.23μg/mL,提示山楂叶多酚具有良好的抗氧化能力,有进一步开发利用的价值。     

山药皮中黄酮、多酚提取工艺优化及其抗氧化活性

为研究山药皮黄酮、多酚的高效提取工艺及其粗提物的抗氧化能力,以山药皮为原料,采用正交法优化超声辅助乙醇提取山药皮中的黄酮、多酚工艺,并对粗提物进行抗氧化活性测定。结果表明：山药皮中黄酮、多酚提取工艺的最佳提取条件为超声时间30 min、乙醇浓度60%、液固比60∶1（mL/g）,在此条件下,黄酮得率为0.929%,多酚得率为0.519%。在一定浓度范围内,粗提物的抗氧化能力随着质量浓度的增加而增强,粗提物具有良好的羟自由基清除作用（IC50 值为0.083 mg/mL）,具有一定的DPPH 自由基清除作用（IC50 值为0.158 mg/mL）,当粗提物质量浓度为1.0 mg/mL 时,其羟自由基清除率、DPPH 自由基清除率、还原力和抗氧化能力分别为81.84%、79.95%、0.70 和0.68。     

高良姜醇提物的抗氧化、酶抑制活性及其与活性成分的相关性

以新鲜高良姜为原料,制备甲醇提取物,分别采用Folin-Ciocalteu法和AlCl3比色法测定多酚和总黄酮含量,并利用DPPH法、ABTS法和FRAP法评价抗氧化功能,同时检测对胰脂肪酶和α-葡萄糖苷酶的抑制功能。结果显示,高良姜醇提物中多酚和总黄酮分别为62.91mg GAE/g DW和13.12mg QE/g DW。当醇提物浓度达到50mg/mL时,对DPPH自由基的清除率达到95.78%,半抑制浓度IC_(50)为6.37mg/mL;对ABTS自由基的清除率达到99.03%,IC_(50)为2.24mg/mL。FRAP值为428.92μmol Fe~(2+)/g DW。醇提物对胰脂肪酶和α-葡萄糖苷酶抑制活性的IC_(50)值分别为205.87,1.32mg/mL。表明高良姜醇提物含有丰富的多酚和黄酮,具有较强的体外抗氧化活性、胰脂肪酶和α-葡萄糖苷酶抑制功能,在降脂降糖药品与功能性食品的开发与应用方面具有很好的前景。     

龙须菜多酚提取工艺优化及其体外抗氧化活性

以龙须菜为原料,研究超声波辅助提取龙须菜多酚的工艺条件及其抗氧化活性。单因素考察液料比、提取温度、超声时间对龙须菜多酚含量的影响,在此基础上,利用响应面分析法优化提取工艺。结果表明,液料比40:1(mL/g)、提取温度60℃、超声时间40min为龙须菜多酚提取最佳工艺条件(龙须菜多酚提取量为1.62 mg GAE/g)。体外抗氧化活性研究表明,龙须菜多酚具有一定清除DPPH自由基和羟自由基的能力,其IC_(50)值分别为56.67,18.78μg/mL,分别相当于15.89,536.4μg/mL的抗坏血酸。     

黄精多酚的闪式提取及抗氧化活性研究

采用闪式提取的方法提取黄精中的多酚类化合物,研究其最佳的提取工艺,同时探讨黄精粗多酚的抗氧化活性。结果显示,闪式提取法提取黄精多酚的最佳工艺为:以50%乙醇为提取剂、料液比为1:20、电压为150 V、提取时间为35 s、提取2次,黄精多酚的提取率较高,为(0.4788±0.0023)%。抗氧化实验表明,黄精多酚粗提物具有较好的总还原能力以及清除DPPH、ABTS自由基的能力,且呈现出良好的量效关系,其总还原能力、清除DPPH和ABTS自由基能力的IC_(50)值分别为27.48、5.21、4.89μg/m L,且均较Vc小。结果提示黄精多酚粗提物具有较好的抗氧化能力。     

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.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status