啤酒糟预处理技术

采用蒸汽爆破、超微粉碎、纤维素酶水解预处理技术对啤酒糟进行了预处理,分析了预处理前后啤酒糟纤维形态结构、纤维组分和还原糖的变化,结果表明,蒸汽爆破预处理技术能有效的破坏啤酒糟中的纤维形态结构,降低中性洗涤纤维(NDF)含量,并提高啤酒糟中还原糖的含量;研究并优化了纤维素酶水解啤酒糟的最佳条件是:酶浓度180U/g,底物浓度为10%,温度为50℃,作用时间为6h;蒸汽爆破后的啤酒糟经纤维素酶水解后,还原糖净增量达12.77mg/mL,NDF基本没有变化。     

以白酒酒糟为原料发酵产丁二酸

以白酒酒糟为原料,经酶法糖化,由Actinobacillus succinogenes发酵生产丁二酸。纤维素酶或糖化酶分别水解白酒糟,在酶反应的最适温度和pH条件下,酒糟中的纤维素和淀粉的水解率分别为44.04%和92.26%,相应还原糖对酒糟的得率分别为110 mg/g和126 mg/g酒糟;但2种酶以分步或同步方式水解白酒糟时,酶水解反应受到产物抑制作用,总还原糖得率仅约为150 mg/g酒糟。采用分步糖化发酵工艺,400 g/L白酒糟经两种酶水解后,得到还原糖58.4 g/L,该水解液发酵产丁二酸28.8 g/L,丁二酸产率72 mg/g酒糟;而采用先用纤维素酶水解白酒糟,再用糖化酶和A.succinogenes同步糖化发酵的工艺,240 g/L白酒糟产丁二酸浓度为32 g/L,产率133 mg/g酒糟。以白酒酒糟为原料发酵生产丁二酸,利用了废弃物,无需外源添加氮源,无需对原料进行酸碱预处理,具有一定的应用前景。     

纤维素酶法测定巴氏杀菌乳中微晶纤维素的研究

应用透析处理、纤维素酶水解与还原糖测定的流程对巴氏杀菌乳中的微晶纤维素进行检测。结果表明,纤维素酶在巴氏杀菌乳中活性稳定,可有效地水解牛奶中的MCC产生还原糖,MCC的检测限达到0.5 mg/mL以下。本研究提供了牛奶中MCC检测的新方法,为乳制品质量控制探索了新的途径。     

表面活性剂对纤维素酶水解过程的影响

分别以湿氧化、稀酸常压水解和蒸汽爆破预处理麦草为底物,考察了不同表面活性剂及用量对纤维素酶解过程的影响.实验表明,添加表面活性剂对纤维素酶水解过程有明显影响;添加非离子型表面活性剂(PEG6000、吐温80)可以提高纤维素的可溶性、可发酵糖的转化水平,其中向湿氧化处理的麦草中加入PEG6000后转化水平提高得最大;而添加离子型表面活性剂对酶解起抑制作用.非离子型表面活性刑和纤维素水解底物的最佳比例大约是0.05 g/g DM.     

机械搅动条件对酸性纤维素酶性能及其处理效果的影响

研究了不同机械搅动条件对酸性纤维素酶吸附和水解性能的影响,结果发现:在高搅动条件下,酸性纤维素酶对纤维素织物的吸附速度更快;由酶水解所释放出的还原糖量也相应增加,引起的织物失重率也更大.测试处理后织物的强力表明,酸性纤维素酶对织物的强力损伤在高搅动条件下更明显.     

表面活性剂改善高固体系木质纤维素酶水解的研究

本研究以木质素磺酸钠为主要助剂,考察其对经金属氯盐预处理的桉木粉在高固体系纤维素酶水解中的影响。结果表明,木质素磺酸钠的加入对高固体系的酶水解效率有较大促进作用,当木质素磺酸钠加入量为0.4%时,酶水解效率可达93.72%,与未添加样相比,酶水解效率提高了12.5个百分点。为进一步提高酶水解效率,将木质素磺酸钠分别与CTAB（十六烷基三甲基溴化铵）和吐温80两种表面活性剂复配,结果表明,表面活性剂复配对高固体系的酶水解效率均有协同促进作用;当m(CTAB)∶m(木质素硫酸钠)为1.5∶1时,酶水解效率可达99.56%;m(吐温80)∶m(木质素磺酸钠)为1∶1时,酶水解效率为99.98%,纤维素基本可完全水解为还原糖。     

酸水解和酶水解对纤维形态结构的影响研究

分别采用盐酸和纤维素酶对漂白针叶木浆进行水解,制得酸水解纤维素和酶水解纤维素,通过分析比较水解后纤维素在聚合度、粒径、微观形态以及理化性能上的区别,研究这两种方法制备的纤维素在形态、结构、性能上的差异。结果表明,漂白针叶木浆经盐酸在高温下水解1 h,纤维素聚合度下降到200左右,纤维平均长度下降到0.1~0.2 mm,经机械粉碎后呈椭圆形颗粒状,平均粒径27.49μm;漂白针叶木浆经纤维素酶水解24 h后,纤维素聚合度降低到700左右,纤维平均长度也下降到0.1~0.2 mm,经机械粉碎后呈棒状颗粒,平均粒径38.77μm。酸水解纤维素较酶水解纤维素具有较大的表观密度、持水力以及较好的流动性。     

纸浆污泥纤维素酶水解的研究

纸浆污泥是制浆造纸工业主要的固体废弃物。由于纸浆污泥中含有至少约40%的纤维素,在污泥处理之前对其中的纤维素进行酶水解,并将葡萄糖转化为生物能源,将极具吸引力。本文详细研究了纸浆污泥纤维素酶水解的影响因素,发现纸浆污泥酶水解系统会促进细菌微生物的生长,消耗生成的葡萄糖,少量的氯胺-T可以消除细菌的负面影响;调节系统初始的pH值到约5.3并稳定之,反应过程的pH值变化都在纤维素酶适宜的范围内。应根据纤维长度来确定酶水解的温度,避免盲目升温到50℃反应而带来的不必要的能量消耗。系统中加入阳离子聚丙烯酰胺量达500mg/L时可以提高酶水解效率约40%。     

酿醋固态废弃物的循环利用

采用先液后固的工艺酿醋时会产生大量富含纤维的废渣,该废渣具有很好的固态发酵特性。文中分析了该残渣的理化性质,以其为培养基,利用两种康氏木霉菌种固态发酵生产纤维素酶,并在此基础上水解醋渣中的纤维素获取还原糖。实验中研究了醋渣的理化性质和含水量、发酵时间以及氮源种类对纤维素酶合成的影响,获得了最高大于4IU/g的酶活。实验还证明了搅拌对水解具有促进作用,并最终获得了大于1%的还原糖溶液,将该溶液用于酿醋的糖化过程,可以取得可观的经济效益。     

酸性酶对纤维素的水解性能

用酸性纤维素酶分别处理棉、粘胶和天丝织物,通过测定处理液中还原糖含量,研究了影响酶水解的各种因素.结果表明,酸性酶对粘胶的水解活力最高,纯棉次之,对天丝织物的活力最低;织物所受前处理条件、酸性酶浓度、机械搅拌条件和不同缓冲体系等对酸性纤维素酶水解性能也会产生影响.经退浆、煮练、漂白后的织物,酶水解能力较高;适当地增加机械搅动,采用HAc-NaAc缓冲体系,酶活力也较高.     

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