漂白废新闻纸脱墨浆白水中DCS的漆酶/介体控制

研究了漆酶/介体对漂白废新闻纸脱墨浆白水中DCS的作用效果,确定了最佳处理条件,并采用GC-MS气质联用仪分析了DCS经漆酶、漆酶/介体处理后成分的变化。结果表明：漆酶可以对DCS中的木素类物质产生降解作用,对酯类、部分脂肪酸、树脂酸也有一定降解作用。漆酶/介体处理可使DCS水的CD值、Zeta电位降低;但电导率、COD、浊度有所增加;胶体物质的平均粒径变小。     

果胶酸类物质的酶解及其对DCS稳定性的影响

选用两种商品果胶酶制剂,首先优化其酶解果胶类物质的反应条件,结果发现,两种果胶酶在pH值9.0,温度为60～70℃的较优条件下可以有效地酶解果胶类物质和马尾松化学机械浆DCS,降低其阳离子需求量(CD值).在探求两种果胶酶酶解果胶类物质的机理时,得出在对PGA类物质(酸性果胶物质)进行果胶酸(盐)裂解酶(PGL)处理以降低CD值时,没有必要将其完全酶解成单体,而只需将其聚合度降为6左右即可.碱性果胶酶(PL)处理果胶时也有类似的结果.同时发现,在漂白浆DCS中的果胶类物质主要是以果胶酸的形式存在,在选用果胶酶时应选用PGL.马尾松化学机械浆DCS经PGL酶处理以后虽然对提高DCS的稳定性作用不大,但可以减缓其沉淀的速度.     

果胶酶处理APMP中DCS的研究

本文研究了APMP浆中DCS水的特性,并且探索了果胶酶处理DCS的工艺条件. 结果表明,DCS中的溶解物质是造成阴离子垃圾的主要原因.果胶酶能降解DCS中产生阴离子垃圾的主要物质果胶酸,酶处理后,阳离子电荷需求量明显降低.不同的温度、pH值、反应时间以及酶用量都会影响阳离子电荷需求量.最佳处理条件为:55℃水浴加热,酶用量150u/L, pH值为4.0,反应时间为1h.     

高压CO_2处理对西瓜汁的影响

以海南麒麟西瓜为原料,榨汁后进行HPCD(高压CO2)杀菌处理,处理温度为25℃,压力为20 MPa和30 MPa,处理时间分别为10、30和60 min,测定HPCD处理后西瓜汁的主要理化指标、细菌总数和PME酶(果胶甲基酯酶)活性变化。结果表明:HPCD处理后西瓜汁pH值降低0.3～0.7、可溶性固形物无明显变化、颜色更红、浊度增加,细菌总数降低可达到2个对数,果胶甲基酯酶活性可降低50%。     

利用果胶酯酶制备低酯果胶工艺研究

研究高酯果胶脱酯工艺的最佳条件;利用果胶酯酶对商品高酯果胶进行脱酯,采用L934正交试验法研究确定酶用量、脱酯温度、pH及脱酯时间对脱酯效果的影响.利用果胶酯酶进行脱酯的最佳工艺参数为:果胶酯酶0.06 g,脱酯温度45℃,脱酯pH 7,脱酯时间70 min,所得果胶甲氧基含量为4.96%.利用酶法制备低酯果工艺简单,脱酯效率较高.     

热处理对桃浊汁流变及果胶结构特性的影响

本研究采用不同热处理鲜榨桃浊汁,考察了桃浊汁流变学及果胶结构的变化特性。处理方式包括:65℃、30 min,95℃、5 min的巴氏杀菌和110℃、3 s的高温瞬时杀菌(UHT)。结果表明:与未处理相比,热处理65℃、30 min处理后桃浊汁的粘度增大,95℃、5 min和UHT处理之后粘度减小;与未处理相比,三种热处理下浊度发生了显著性变化(p0.05),悬浮稳定性没有显著的变化(p0.05),桃浊汁中果胶酯化度显著增大,由82.87%升至96.17%(p0.05),分子量在UHT处理之后由267.17 k Da增至331.08 k Da,桃浊汁的浊度和悬浮稳定性与果胶的分子量、酯化度以及果胶甲基酯酶(PME)酶活间均表现出不同程度的相关性。果胶的特征官能团在发生了变化,其中COO-的振动增强。SEM结果表明热处理后果胶微观形态为均一的网络结构,PME酶活由0.041 U/m L降至0.018 U/m L。热处理使桃浊汁流变学特征指标、果胶结构发生了变化,为鲜榨桃浊汁加工技术研发和品质提升提供依据。     

电导率对聚胺固着剂作用于造纸循环白水的影响研究

将聚胺固着剂作用于电导率不同的两种白水,探讨了电导率对其作用效果的影响.结果表明,不同电导率条件下,聚胺均能明显地增大较小胶体粒子的粒径,或将较小的粒子固着到较大的粒子上,同时降低白水的浊度、色度、阳离子需求量、COD和DCS含量.电导率上升对聚胺作用于白水的效果有一定的削弱作用,但相对而言,其降低浊度和色度的能力被削弱的程度较小,将小粒子直接凝聚到大粒子之上以及降低阳离子需求量、COD和DCS含最的能力被削弱得比较明显.综合分析认为,高电导率条件下聚胺仍能提供较好的处理白水的效果.     

黑曲霉果胶酯酶在毕赤酵母中异源表达、性质分析及脱酯工艺优化

果胶酯酶作为一种食品酶制剂,因其能够将高酯果胶的甲酯基脱去生成低酯果胶而受到广泛关注,但目前国内尚无自主研发的商品果胶酯酶。为了促进果胶酯酶的应用,该研究合成了密码子优化后的黑曲霉果胶酯酶基因,并实现了其在毕赤酵母X33中成功表达。3 L发酵罐高密度发酵96 h后,得到的发酵液上清液中果胶酯酶的活力为85.12 U/mL,是摇瓶水平的7倍,也是目前果胶酯酶表达的最高水平。对重组果胶酯酶进行分离纯化和酶学性质研究,结果表明,重组果胶酯酶的最适pH和最适温度分别是pH 5.0和55℃,K_m和V_max分别是13.8 mmol/L和9.04μmol/(L·min)。该酶的温度稳定性较好,在55℃处理40 min,剩余活力仍保持在60%以上;其pH耐受范围广,在pH 3.5～6.5下处理120 min,仍保持60%以上的剩余活力。以高酯果胶为底物,对该果胶酯酶的脱酯条件进行优化,优化得到的脱酯工艺参数为：30 g/L果胶、加酶量65.4 U/g、脱酯温度50℃、初始pH 5.5、脱酯时间60 min。在此条件下果胶的酯化度从70.8%降至13.6%。该...     

黑曲霉果胶酯酶的研究

黑曲霉(As3.3324)用高甲氧基果胶诱导,当接种量为3×103个孢子,30℃恒温培养,转速90r/min,液体培养4d时果胶酯酶的活力最大,为90.2U/mL培养基。该果胶酯酶能将高甲氧基果胶的酯化度从64.54%降低到45.70%。经果胶酯酶作用后低甲氧基果胶的粘度为0.006Pa·s,与同样条件处理的高甲氧基果胶的粘度0.007Pa·s相差不大。     

果胶甲酯酶对泡菜脆度的影响研究

利用果胶甲酯酶对果胶具有去甲酯化作用的原理,选用萝卜为泡菜原料,在一定钙盐存在的条件下,探讨果胶甲酯酶处理的最佳条件.结果表明,果胶甲酯酶处理泡菜原料,在一定钙盐存在的条件下,萝卜泡菜的脆度得到了很大提高,且萝卜泡菜保脆的最佳果胶甲酯酶作用条件为酶添加量0.9 mL酶液/dL水(萝卜100 g)、PH值4.5、温度45℃.     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press