稀酸预处理玉米芯提取木糖的研究

通过单因素实验法和正交实验法优化了以玉米芯为原料制备木糖实验过程中各工艺参数,包括固液比、酸浓度、处理温度以及处理时间。结果表明,稀酸预处理过程各因素对玉米芯木糖提取率影响程度由大到小的顺序为:处理温度酸浓度处理时间。且在降低酸浓度和减少反应时间的情况下,仍可使木糖得率达到较高的水平,优化的实验条件为:固液比1∶10,酸浓度1. 2%,处理温度120°C,处理时间90 min。在此条件下,木糖得率可达86. 36%。     

Box-Behnken法优化玉米秸秆预处理工艺对酶解糖化的影响

为促进生物炼制产业发展,提高玉米秸秆酶解糖化效率,运用Box-Behnken试验设计优化预处理工艺,研究硫酸质量分数、反应时间、反应温度和固液比四个因素对半纤维素水解率的影响规律,并结合扫描电子显微镜、红外光谱仪、X-射线衍射仪分析玉米秸秆微观形貌、结构等指标。结果表明：玉米秸秆预处理最佳工艺为反应温度100℃、硫酸质量分数1.2%、反应时间120 min、固液比1∶9（g∶mL）,在此条件下半纤维素水解率为84.93%,木质素脱除率为46.15%,预处理水解液还原糖质量浓度为2.04 g/100mL,木糖产率为74.22%,87.89%纤维素保留在固体部分,经72 h酶解反应酶解率达到85.79%,未处理玉米秸秆酶解率仅为32.25%。     

低聚木糖的酶法生产

确立了玉米芯经稀酸预处理后加水蒸煮提取木聚糖 ,然后再加酶水解提取液的生产低聚木糖的工艺路线 .玉米芯在质量分数为 0 .1%的H2 SO4 溶液中于 6 0℃下浸泡 12h后 ,滤去浸泡液并水洗至 pH 6左右 ,然后采用液固比 10∶1,150℃ ,30min的蒸煮条件进行蒸煮 .结果表明 ,可溶性木聚糖的提取得率达 17% (按玉米芯计 ) ,提取液的RS/TS小于 33% .提取液和渣一起用木聚糖酶进行水解 ,可获得阿拉伯糖 /葡萄糖 /木糖 /木二糖 /木三糖之比为 7.7∶6 .8∶11.5∶54.1∶19.8的高纯度低聚木糖产品 .低聚木糖的质量分数大于 70 % (对总糖 ) ,且产品的可溶性总糖得率达2 6 .4 % (对玉米芯 ) .     

NaOH预处理对甘蔗渣成分和酶解效率的影响

利用NaOH预处理甘蔗渣,通过不同浓度、温度、固液比和处理时间对甘蔗渣成分含量、固体得率、物理结构和酶解效率进行了研究。结果表明:NaOH浓度、预处理温度和预处理时间是影响甘蔗渣成分的关键因素。当NaOH浓度为13%、处理温度为70℃、处理时间为50 min时,半纤维素含量由原来的17.43%分别下降到9.87%、8.25%和10.17%;纤维素含量由原来的48.32%分别下降到37.56%、35.65%和38.25%;木质素含量由原来的18.75%分别下降到15.23%、15.98%和15.23%。处理温度对固体得率影响较大,在30℃时,甘蔗渣固体得率最高为98.25%;在50℃时,甘蔗渣固体得率最低为54.2%,而浓度、固液比和处理时间影响相对不明显。不同碱浓度、温度、固液比和处理时间对甘蔗渣物理结构都有不同程度的影响,处理后的甘蔗渣物理结构受到破坏,内部结构变得疏松多孔。根据酶解效率实验得出的最佳预处理条件为:浓度10%、温度50℃、固液比1︰16、处理时间30min,在此条件下预处理甘蔗渣产物还原糖质量分数在16%左右。     

从笋壳中提取木聚糖研究

竹笋壳是竹笋加工当中的大宗废弃物,是一种极具开发潜力的资源.木聚糖是许多植物细胞壁中半纤维素的主要组分,是由β-1,4木糖苷键连接的以D-木糖残基为主链的复杂分子多聚糖.通过降解木聚糖可以得到功能性食品低聚木糖.本研究以竹笋壳为原料,采用了制备综纤维再碱抽提方法,分析了碱溶液质量分数、固液比、提取温度和提取时间对提取木聚糖得率的影响.碱提取竹笋壳中木聚糖的方法为:碱质量分数为5％,固液比为(g∶mL) 1∶10,提取时间为3h,提取温度为120℃.木聚糖提取率达到原料质量的24.77％.实验结果表明,笋壳中含半纤维素为35.08％,与目前生产低聚木糖的主要原料玉米芯中半纤维素的含量相当,是提取木聚糖的较好资源.本研究为笋壳制备低聚木糖奠定了坚实的基础,也为笋壳资源的综合利用提供了基础数据.     

水热预处理对制备桉木溶解浆的影响研究

本研究利用水热预处理方法辅助制备桉木溶解浆,并研究了水热预处理最高温度、保温时间、pH值对硫酸盐法制浆得率的影响。结果表明,未漂浆得率随预处理程度的增大而逐渐下降,其中半纤维素的溶出随水解液pH值的升高而增加,在较高pH值下主要以低聚木糖的形式大量溶出,水解液pH值对未漂浆得率的影响显著。研究还发现,漂白浆白度和α-纤维素含量均随水解液pH值的升高而增大。最佳的水热预水解工艺条件为:最高温度170℃、保温时间60 min、pH值4.9。水热预水解后,经硫酸盐蒸煮和无元素氯(ECF)漂白后,获得的浆料综合性能最好,浆料白度93.3%,α-纤维素含量93.32%,达到溶解浆的品质要求。红外光谱表明,水热预处理可以很好地去除原料中的半纤维素。     

水热预处理过程中pH值对玉米秸秆水解特性的影响

本研究采用乙酸或NaOH调节水热预处理的pH值,通过分析玉米秸秆中纤维素、半纤维素和木素降解产物的变化,研究了水热预处理的pH值对玉米秸秆水解特性的影响。结果表明,在水热预处理过程中,乙酸的添加促进了纤维素和半纤维素降解,但木素溶出率略有下降,水解液中木糖、低聚木糖、葡萄糖等糖类物质含量增加,糠醛和5-羟甲基糠醛等物质含量快速提升;当NaOH用量小于3%时,随着NaOH用量增加,纤维素和半纤维素降解减少,NaOH主要消耗于半纤维素中的乙酰基脱除;当NaOH用量为3%时,此时水热预处理终点pH值为5.84,固体物料得率达到最大值为75.15%;继续增加NaOH用量,木素的溶出率开始增加,固体物料得率下降。结果显示pH值可以成为调控水热预处理水解效果的重要手段。     

响应面试验优化芦笋茎秆微晶纤维素的制备工艺

以芦笋茎秆为原料,采用稀酸水解法制备微晶纤维素。以微晶纤维素得率为指标,对试验中酸水解条件盐酸质量分数、料液比和水解温度进行优化,并在单因素试验基础上通过响应面试验选出最优的制备工艺条件。结果表明:在水解时间60 min时,制备芦笋茎秆微晶纤维素的最佳工艺条件为盐酸质量分数6%、料液比1︰20(g/m L)、水解温度95℃,此条件下微晶纤维素得率达到43.57%。     

桉木粉在低共熔溶剂中制备纳米结晶纤维素

采用氯化胆碱-丙三醇-聚乙二醇200混合溶剂液化桉木粉的方法分离纤维素,再通过氯化胆碱-草酸二水合物低共熔溶剂(DES)在不同的条件下处理提取的纤维素制备纳米结晶纤维素(CNC)。探讨了固液比、温度以及时间对CNC得率的影响,用扫描电镜、透射电镜、红外光谱、X-射线衍射、Zeta电位、紫外可见光分析对制备的CNC进行了表征。结果表明,在固液比1∶100,温度100℃,反应时间4h的条件下,CNC的得率最高,可以达到90.06%;制备的CNC呈棒状结构,直径为3~13nm,长度为100~300nm;结晶度相比于原料纤维素略有降低,纤维素结构没有发生大的变化,仍然呈纤维素Ⅰ型结晶。     

乙酸强化水热预水解对相思木半纤维素溶出及组分与结构的影响

在170℃下,分别采用水热预水解法和1.0%（质量分数）乙酸强化水热预水解法抽提相思木,通过乙醇沉淀法回收预水解液中的半纤维素,分析了乙酸对预水解液中溶解半纤维素的化学组分及含量、乙醇沉淀半纤维素回收率及其组分和结构的影响。结果表明,乙酸可显著提高预水解液中低聚糖和总糖含量;在170℃下预处理35 min时,乙醇沉淀半纤维素回收率最大;离子色谱和紫外光谱分析结果表明,乙酸强化水热预水解乙醇沉淀半纤维素的化学组分与水热预水解乙醇沉淀半纤维素相同,但木糖和木素含量较高,而阿拉伯糖和半乳糖含量偏低;凝胶色谱分析结果表明,乙酸强化水热预水解乙醇沉淀半纤维素平均分子质量低于水热预水解乙醇沉淀半纤维素;核磁共振分析结果表明,乙酸强化水热预水解乙醇沉淀半纤维素聚木糖主链上残留阿拉伯糖支链较少,有明显木素 碳水化合物复合体（LCC）存在。     

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.