碱预处理对制备微晶纤维素的影响

为了加快酸水解制备微晶纤维素(Microcrystalline cellulose,MCC)时酸液的渗透效率,提高酸水解反应在纤维素纤维细胞壁内的区域反应均匀性,从而提升MCC的质量。本研究采用NaOH溶液对针叶木溶解浆进行有限润胀预处理,并通过激光粒度分析仪、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱仪(FT-IR)及热重分析仪(TGA)等对MCC的各项质量指标进行检测,探究了碱预处理对酸水解制备MCC的影响。结果表明,在最佳NaOH质量分数(9%)预处理后,MCC平均粒径由52.1μm降低至41.8μm,粒径分布更加集中,MCC结晶度基本保持不变;碱预处理对纤维素纤维及MCC化学结构和热稳定性均无明显影响。     

纤维素高值化利用制备微晶纤维素

以溶解浆为原料,通过Fe3+作为催化剂酸水解、分离、纯化制备微晶纤维素(MCC)粗产品。确定最优的稀酸水解浓度和Fe3+浓度,同时对水解残液成分进行初步分析。最终水解条件为,水解温度80℃,Fe3+浓度0.3 mol/L,水解时间60 min,HCl浓度2.0 mol/L。对制备的MCC分析与表征结果表明,MCC主要成分为纤维素,其晶型结构仍为纤维素Ⅰ型,结晶度为73.0%,与原料相比增加了18.2个百分点,聚合度下降至100左右;所得的MCC质均长度集中分布在200~400μm之间;水解残液中还原糖得率为1.56%。     

碱化预处理对高压射流超微细化纤维素的影响

为了揭示纤维素超微细化处理后的结构和物性变化,利用高压射流技术对两种纤维素微粉(原样、碱处理)悬液进行了湿法破碎,检测了产物微观形态、粒径分布、比表面积以及结晶度的变化。结果表明,高压射流处理(130 MPa,100μm单孔阀,4次)可使原样和碱化(10%NaOH,70℃,1 h)后的纤维素微束直径由原料的5.0〜50.0 pm分别降至0.5〜5.0μm和0.1〜1.0μm,微束长度由原料的20.0〜200.0降至1.0〜10.0粒径分布曲线峰值可由原料的158.0μm降至10.0μm左右;比表面积分别提高3.0倍和5.5倍。碱化处理可降低纤维素无定形区的强度进而降低纤维素的破碎能。纤维素原样经高压射流后结晶度改变不明显;碱化预处理后高压射流处理产物的结晶度小幅度(10%)下降。碱化预处理增强了高压射流处理纤维素原料的微细化程度。     

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。     

棉秆皮微晶纤维素制备及得率分析

以棉秆皮为原料制备棉秆皮微晶纤维素。探究了水解温度、H_2SO_4质量分数、水解时间对棉秆皮微晶纤维素得率的影响,通过响应面优化分析确定最优酸水解工艺条件,在此基础上,进行超声波辅助酸水解单因素试验,确定了最优制备工艺条件。结果表明:当水解温度为45℃、H_2SO_4质量分数为49%、水解时间为2 h、超声功率为300 W、超声时间为10 min时,棉秆皮微晶纤维素结晶度为69.57%,粒径为6.58μm,得率高达79.86%。     

玉米芯残渣的底物特性对其酶水解效率的影响

利用农业废弃物进行生物质精炼以生产生物质燃料对于缓解能源危机和降低环境污染具有重要意义。酶水解玉米芯残渣生产可发酵糖,通过PFI打浆预处理改变玉米芯残渣的底物特性,进而借助主成分分析和多元线性回归分析方法研究了玉米芯残渣的底物特性对其酶水解效率的影响。结果表明,PFI打浆可明显改变玉米芯残渣的底物特性,显著提高其酶水解效率;玉米芯残渣的酶水解反应符合拟二级反应模型;建立了酶水解效率与底物特性之间的多元线性回归模型;保水值和打浆度对酶水解效率的影响最显著,平均粒径和比表面积的影响次之,而表面电荷密度的影响最小。     

三元DES预处理杨木屑促进纤维素酶水解的研究

采用由对甲基苯磺酸、氯化胆碱和乙醇组成的新型三元低共熔溶剂（DES）对杨木屑进行预处理,研究了三元DES预处理对杨木屑木质纤维化学组分、微观形态、结晶结构、化学结构及纤维素酶水解效果的影响。结果表明,和杨木屑原料相比,二元DES预处理物料的木质素脱除率不升反降,而添加乙醇的三元DES预处理物料的木质素脱除率提高至69.2%;三元DES体系可有效抑制物料表面酸不溶物质的形成,减少纤维素酶的无效吸附,可将纤维素酶水解效率提高至76.6%;在三元DES预处理过程中,半纤维素、木质素以及纤维素无定形区结构的破坏导致纤维素结晶度由原料的48.7%提高至65.7%,纤维素结晶指数由0.66提高至0.76。     

生物酶预处理对烟梗浆料纤维特性的影响

通过采用生物酶对烟梗浆料进行预处理,对比分析了生物酶预处理对烟梗浆料纤维特性的影响。结果表明,相同打浆度下,酶预处理组纤维平均长度、粗度、细小纤维含量和扭结指数均高于对照组。烟梗浆料扫描电子显微镜(SEM)分析表明,酶预处理有促使纤维纹孔打开、破坏细胞结构的可能;红外光谱表明,酶预处理后烟梗浆料中的纤维素相对含量增加,而烟碱类物质相对含量减少,溶出增加;X射线衍射仪(XRD)分析表明,酶预处理可提高烟梗浆料纤维素的结晶度,相对于对照样的26. 19%,酶预处理样纤维素结晶度为28. 15%,增加了7. 51%;热重分析表明生物酶预处理会提高烟梗浆料的热稳定性。     

金属离子催化纤维素酸水解制备微晶纤维素的研究

本文以漂白阔叶木浆为原料,研究了制备微晶纤维素过程中不同金属离子对纤维素酸水反应的催化作用,并采用X射线衍射图谱(XRD)、扫描电镜(SEM)等方法对水解纤维素进行了分析和表征。结果表明,添加Fe3+、Al3+、Cu2+和Co2+有利于促进纤维素的酸水解反应,其中Fe3+的催化作用最佳;当Fe3+的浓度为0.3mol/L时,水解纤维素的得率为91.27%,聚合度为166,达到了微晶纤维素的极限聚合度;XRD分析表明,添加Fe3+更有利于纤维素无定形区的选择性酸水解,提高水解纤维素的结晶度。     

LPMO结合硫酸水解制备纤维素纳米晶体

以棉溶解浆为原料,使用裂解性多糖单加氧酶（LPMO）预水解结合硫酸水解制备纤维素纳米晶体（CNC）,对LPMO预水解前后纤维的微观形态和制得的CNC进行了粒径、结晶度和微观形态等表征,并与仅硫酸水解制备的CNC进行对比。研究发现,采用质量分数60%硫酸水解时,经LPMO预水解得到的CNC比仅硫酸水解制备的CNC平均粒径减少22 nm,结晶度提高8.8个百分点,得率提高19.3个百分点。在LPMO预水解后,随着硫酸质量分数降低,CNC的得率和羧基与磺酸基总量减少,粒径上升,而结晶度无明显正比关系。从LPMO作用整体效果来看,预水解结合50%硫酸得到的CNC与对照组相比粒径增加9 nm,羧基和磺酸基总量略小,而结晶度提高6.4个百分点,得率提高18.4个百分点,其原子力显微镜（AFM）表征显示已达到纳米水平。故通过LPMO预水解结合50%硫酸即可制得CNC,这可降低对工业生产上设备耐酸能力的要求。但LPMO反应周期长,因此在实际工业应用中有待进一步研究。     

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.     

Review of techniques to manufacture micro-hydrogel particles for the food industry and their applications

Microgels are ‘soft’ microscopic cross-linked polymeric particles that are being increasingly exploited in a variety of industries for rheology control, encapsulation and targeted delivery. They are valued because of the ability to tune their functionality to address specific applications in oil recovery, coatings, drug delivery, cosmetics, personal care and foods. Food microgels are typically biopolymer hydrogels in the form of microspheres, nanospheres (also called nanogels), spheroids and fibres. The utilisation of engineered microgels in foods has so far been limited, despite their great potential to address several needs in the food industry, including: satiety control, encapsulation of phytonutrients and prebiotics, texture control for healthier food formulations (e.g. reduced fat products), and targeting delivery to specific areas in the digestive tract. We review the scientific and patent literature on the utilisation and manufacturing methods for producing microgels with an emphasis on micro-hydrogels for food applications.     

12—A CRITIQUE OF SOME HYPOTHESES RELATING TO THE HETEROGENEITY OF THE HIGH-SULPHUR PROTEINS OF WOOL

Joubert and Burns prepared a large number of fractions from the high-sulphur proteins of wool and estimated their molecular weights and amino-acid compositions. Their data have been re-examined in order to look for statistically significant interrelations between amino acids and between the proportion of various amino acids and molecular weight. Statistical analysis of the data is also used to examine the credibility of some hypotheses concerning the mechanism of keratin biosynthesis and to provide further evidence for the existence of families of proteins within the high-sulphur fractions of wool.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of     

The Latest Data about Development of Chinese Printing Industry in 2013

In the 2014 China（Shanghai）International Printing Week,Director Wang Yanbin released the latest data about development of Chinese printing industry in 2013.According to statistics,in 2013,the total output value of Chinese printing industry exceeded 1trillion Yuan for the first time,reaching 1.03985 trillion Yuan.There were 105,000 printing enterprises in China,employees were 3.415 million.The total asset was 1.06247 trillion Yuan;     

The State Council Issued "Directory of Government Approved Investment Projects(2013 Edition)"

正On December 2nd,2013,the State Council issued the notification of"Directory of Government Approved Investment Projects(2013 Edition)"(hereafter referred to as"notification").It is pointed out in the"notification"that in order to further deepen reforms in investment systems and administrative examination and approval systems,simplify administrative procedures and delegate powers to lower levels,earnestly     

China textile machinery: taking off in progress

正Among the 1600 exhibitors who take apart in the ITMA ASIA+CITME2014 2/3 are Chinese manufactures.If the numerous figures failed to attract your attention,the increase of quality should draw your focus.To adopt the demand of developing textile machine market,domestic textile machinery enterprises now follow the slogan of"technology drives development"to enhance product competitiveness.Our domestic sellers will showcase product ranging from spinning,weaving,dyeing and printing,     

Top Ten News of China's Paper Industry 2013

On December 24th, 2013, the meeting on the selection of top 10 news of China＇s paper industry 2013 sponsored by 〈China Paper Newsletters〉 was held in Beijing. The yearly selection of the top l0 news, which began in 2000, has become a brand activity widely recognized in the industry thanks to the support from the authorities at all levels and public participation.