豆渣中可溶性多糖的不同提取方法比较和工艺优化

该研究分别利用超声辅助提取法和复合酶解提取法对豆渣中可溶性多糖进行提取,以多糖得率为考察指标,对提取工艺进行了优化。超声辅助提取法利用超声辅助热水浸提多糖,其最佳工艺条件为超声功率140 W、浸提温度70℃、浸提时间3 h、料液比1∶20,此条件下多糖得率为6.13%。复合酶解提取法利用纤维素酶与酸性蛋白酶进行酶解提取多糖,其最佳工艺条件为酶添加量2.5%、浸提温度60℃、浸提时间1 h、料液比1∶30,此条件下多糖得率为7.72%。通过化学组成分析,两种方法提取的多糖的单糖组成基本相似,主要由甘露糖、葡萄糖和半乳糖组成,但复合酶解提取法所得多糖的总糖含量和糖醛酸含量均高于超声辅助提取法。由红外光谱分析可知,两种提取方法均未对豆渣中可溶性多糖的特征官能团产生破坏。综合比较分析,复合酶解提取法提取时间短,提取温度低,多糖得率较高,是提取豆渣可溶性多糖的最佳方法。     

不同方法提取的羊栖菜多糖理化性质及益生活性

本研究以羊栖菜为原料,分析了热水提取、超声辅助水提法、脉冲电场辅助水提法和纤维素酶辅助水提法4种提取方法所得多糖的理化性质和益生活性。首先对4个多糖的得率、分子量、单糖组成和流变特性进行了测定,然后将4个多糖分别添加到乳杆菌发酵培养基中替代葡萄糖作为碳源进行体外发酵,以评价其促进乳杆菌增殖活性的能力。结果表明,纤维素酶辅助水提取(E-SFP)所得多糖的得率最高,为14.02%,其次分别为超声辅助水提取U-SFP(12.57%)、脉冲辅助水提取P-SFP(10.38%)、热水提取H-SFP(7.07%);4个多糖的平均分子量在200～245ku之间,主要由岩藻糖、葡萄糖、半乳糖、甘露糖和木糖组成,岩藻糖和半乳糖是主要成分,其中E-SFP的单糖组成中葡萄糖的含量较其它3个多糖的高,达到了19.57%;4个多糖为典型的非牛顿流体,且表观粘度与分子量呈正相关;与空白组比较,4个多糖都能一定程度促进乳杆菌的增殖,其中E-SFP的促增殖作用显著高于其它3个多糖(p0.05)(发酵48 h,OD600值达到0.50)。综合比较发现,采用纤维素酶辅助水提取所得羊栖菜多糖的得率最高,对乳杆菌的增殖活性最佳,本研究结果可为羊栖菜多糖的制备及其益生活性研究提供参考依据。     

超声波协同半仿生法提取黑木耳多糖工艺优化

对超声波协同半仿生法提取黑木耳多糖的工艺进行优化,以黑木耳多糖提取率为指标,采用单因素试验和正交试验,确定最佳提取工艺参数。结果表明,超声波协同半仿生法提取最佳工艺参数为:料液比1∶30(g/mL),超声温度60℃,超声功率500 W,超声时间60 min,在此条件下,黑木耳多糖提取率为22.52%。     

超声波提取黑木耳多糖及其体外抗凝血活性

通过单因素,正交试验对黑木耳超声波提取优化,经过离子交换层析柱纯化,对多糖组分抗凝血活性的初步研究。粗多糖提取最佳工艺条件为,超声频率为70 k Hz、料液比为1∶30(g∶m L)、超声时间为15 min、超声温度为70℃,黑木耳粗多糖得率为6.15%。粗多糖经阴离子交换柱DEAE Sepharose CL-6B分级纯化得4个组分AAP-1、AAP-2、AAP-3、AAP-4。活化部分凝血活酶时间(APTT)初步表明,黑木耳多糖组分AAP-2、AAP-3具有抗凝血活性。     

竹茹多糖提取工艺优化及其理化性质分析

以蒸汽爆破预处理后的竹茹为研究对象,采用水提醇沉法提取竹茹多糖,在单因素实验基础上进行正交实验优化粗多糖的制备,粗多糖经过复溶、过滤、二次醇沉等处理纯化得到精制竹茹多糖,并对其理化性质进行分析测试。竹茹多糖提取的优化工艺参数为:料液比1∶15(g/m L),提取温度100℃,提取时间2.5 h,粗多糖得率为2.65%;粗多糖进一步精制获得纯度为80.75%的精制竹茹多糖(BSP),得率为2.25%。理化性质分析结果表明,BSP的化学组成主要有多糖(80.75%)、木质素(5.45%)和酚酸(3.21%),BSP的单糖组成主要有木糖和葡萄糖,重均分子量约为7.6 ku,BSP水溶液为假塑性流体。     

黑木耳多糖的降解及其产物抗氧化性

采用水提醇沉法提取黑木耳多糖（Auricularia auricula polysaccharide,AAP）,用三氟乙酸（trifluoroacetic acid,TFA）降解黑木耳多糖,经单因素和响应面试验优化降解条件;纯化后多糖采用高效凝胶渗透色谱、红外光谱、高效液相色谱测定多糖分子量、红外谱图及单糖组成并测定多糖的体外抗氧化活性。结果表明：TFA浓度为0.8 mol/L、温度为78.2℃、降解2.1 h,降解黑木耳多糖的DPPH自由基清除率为70.37%。降解后黑木耳多糖分子量由148.2 kDa变为37.5 kDa,特征官能团结构及单糖组成无明显变化,为分子修饰黑木耳多糖提供试验基础。     

响应面法优化超声协同复合酶分步提取恰玛古多糖工艺

以恰玛古多糖得率为指标,在超声提取及复合酶酶解单因素实验基础上,采用响应面法探究超声协同复合酶分步提取恰玛古多糖的最佳工艺条件。结果表明,超声协同复合酶分步提取恰玛古多糖的最佳提取工艺为:液料比33:1 mL/g,超声温度62℃,超声功率250 W,超声提取43 min后加入2.5%的复合酶(纤维素酶:木瓜蛋白酶:果胶酶=1:1:1,质量比),酶解pH5.4,酶解温度50℃,酶解时间52 min,在此条件下,恰玛古多糖得率为12.62%±0.18%。超声协同复合酶提取恰玛古多糖的得率较高,且工艺简便易行,适用于恰玛古多糖的提取。     

不同提取方法对小麦麸皮多糖化学组分及免疫调节活性的影响

目的:以小麦麸皮超微粉为实验材料,分别用酸法、碱法、水提和酶法提取获得多糖,研究不同提取方法对小麦麸皮多糖得率、提取后麸皮残渣微观形态、糖醛酸含量、硫酸根含量、蛋白质含量、单糖组成及免疫调节活性的影响。方法:采用苯酚-硫酸法测定多糖含量,硫酸-间羟基苯酚法测定糖醛酸含量,BaCl₂-明胶法测定硫酸根含量,气相色谱法测定单糖组分;采用MTT检测细胞毒性,Griess法测定细胞上清液中NO含量,Western Blot法检测细胞诱导型一氧化氮合成酶(iNOS)和环氧合酶-2(COX-2)蛋白表达。结果:碱提法获得的粗多糖得率最高,为31.73%,测定提取的粗多糖中多糖含量为57.79%;小麦麸皮多糖中糖醛酸和硫酸根的含量依次为:碱提法>酶提法>酸提法>水提法;不同提取方法的小麦麸皮多糖组分中所含单糖的种类为阿拉伯糖、木聚糖及葡萄糖;MTT法检测四种小麦麸皮多糖对细胞均无毒性,其中水提多糖能促进RAW264.7细胞分泌NO因子并能促进细胞诱导型一氧化氮合成酶和环氧合酶-2蛋白的表达。结论:四种不同提取方法所得到的小麦麸皮多糖的得率、化学组成成分及生物活性各不相同,采用传统水提法工艺提取多糖更利于维持多糖的免疫调节活性。     

复合酶协同超高压法提取黑木耳多糖的工艺优化

该试验研究复合酶协同超高压法提取黑木耳多糖最佳工艺条件。以黑木耳多糖得率为指标,采用单因素试验和正交试验,确定最佳提取工艺参数。结果表明,复合酶提取最佳工艺参数为酶解时间50 min,复合酶（纤维素酶∶木瓜蛋白酶=1∶1,质量比）添加量3%,酶解温度50℃,酶解pH值6.5。在此条件下,黑木耳多糖得率为9.26%。经复合酶法优化后,再进行超高压法提取,最佳工艺参数为保压时间8 min,提取温度50℃,压力400 MPa,料液比1∶30（g/mL）。在此条件下,黑木耳多糖得率为12.23%。     

半枝莲粗多糖提取工艺及单糖组分的研究

目的:优化半枝莲粗多糖的提取工艺并测定其单糖的组成.方法:通过单因素实验及正交实验得出不同因素对半枝莲粗多糖提取率的影响,并用气相色谱法测定粗多糖的单糖组成.结果:半枝莲粗多糖提取的最佳工艺为:提取温度60℃,料液比1:20,提取时间2h,提取次数4次,提取率为2.823%.气相色谱分析结果表明,半枝莲粗多糖主要由7种单糖组成.结论:采用优选的最佳工艺提取半枝莲粗多糖,提取率显著提高,优选的最佳工艺稳定可行,分析得到粗多糖的组分为阿拉伯糖、鼠李糖、核糖、甘露糖、果糖、半乳糖和葡萄糖等.     

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