高浓玉米秸秆碱法预处理及半同步糖化发酵生产乙醇的工艺研究

为实现玉米秸秆高效转化可发酵糖,提升玉米秸秆生产纤维素乙醇竞争力,对碱过氧化氢法预处理后高浓玉米秸秆半同步糖化发酵生产燃料乙醇的工艺进行了研究。建立底物浓度与酶解糖得率关系模型,以确定适宜的底物浓度。向预处理后的玉米秸秆中添加吐温20,考察其酶解过程特性,确定吐温20最适添加量。结果表明,酶解最适条件为:底物质量浓度200 g/L,吐温20添加量8%(ω)。在该条件基础上,对酵母种龄、吐温20对酵母发酵影响、半同步糖化发酵预酶解时间、半同步糖化发酵的时间、发酵温度进行了研究,确定了半同步糖化发酵的工艺条件为:种龄16 h,吐温20添加量5%(ω),预酶解时间9 h,半同步糖化发酵时间7 d,温度34℃。在最佳条件下,发酵7 d后,乙醇浓度达到23. 64 g/L,乙醇转化率达到76. 54%,较对照组(不添加吐温20)转化率提升3. 41%。该工艺条件下能实现高浓玉米秸秆高效转化可发酵糖及乙醇的目的。     

稀酸预处理玉米秸秆的糖化和同步发酵

利用木质纤维原料生产生物乙醇作为石油的代替能源是近年来各个国家力求攻关的课题之一。在本实验中,我们选取了两个稀酸预处理条件：①170℃,30min,1：8,酸浓度1．875％;②170℃,60min,1：20,酸浓度0．75％,对玉米秸秆进行预处理,并对预处理后的固体物料进行了糖化和同步糖化发酵试验。结果表明,在糖化实验中,1号预处理条件得到的玉米秸秆其纤维素转化率为89．85％,2号预处理条件得到的玉米秸秆其纤维素转化率为81．13％。在同步同化发酵实验中,这两个预处理条件得到的玉米秸秆其最终的乙醇得率为理论值的78％和97％。说明了糖化和同步糖化发酵为两个不同的工艺阶段,其中同步糖化发酵工艺受环境的影响更多些。     

酸预处理麦秆半同步和同步糖化发酵制乙醇条件优化

麦秆首先进行盐酸预处理,然后以盐酸预处理麦秆为底物通过正交实验优化了底物半同步和同步糖化发酵制乙醇条件。利用XRD对原料、酸预处理麦秆和发酵麦秆的结构特征进行分析。结果表明:盐酸预处理的麦秆半同步糖化发酵制乙醇的最佳条件为发酵温度36℃、酵母接种量0.1%、酶质量浓度0.8 g/L和发酵时间2 d,此时乙醇含量为19.16 g/L;盐酸预处理的麦秆同步糖化发酵制乙醇的最佳条件为发酵温度39℃、酵母接种量0.1%、酶质量浓度0.5 g/L和发酵时间4 d,此时乙醇含量为19.44 g/L;同步糖化发酵优于半同步糖化发酵;XRD分析表明酸预处理和发酵后,麦秆的结晶度降低。     

γ射线辐照预处理玉米秸秆发酵产乙醇的研究

该研究探讨了脱毒处理对基于辐照处理的玉米秸秆发酵产乙醇的影响,发现氢氧化钙处理对辐照处理玉米秸秆中的甲酸、 乙酸的脱除效果最佳,硼氢化钠处理对糠醛、对羟基苯甲酸、香草酸、丁香酸、对香豆酸脱除效果最佳,经过硼氢化钠、氢氧化钙及水 脱毒处理后的玉米秸秆乙醇转化率分别为73.6%、70.8%、66.7%,均显著高于对照（56.0%）（P＜0.05）;初步研究了发酵工艺与辐照预 处理的适配性,发现在分步糖化发酵（SHF）、变温同步发酵（NSSF）、半同步糖化发酵（HSSF）和同步糖化发酵（SSF）工艺条件下,辐照 预处理玉米秸秆的乙醇转化率分别为41.9%、41.9%、39.6%和55.9%,说明SSF与辐照预处理的适配性最佳。     

水稻秸秆同步糖化发酵生产燃料乙醇的研究

研究了培养基起始pH、发酵时间、发酵温度、酵母接种量和吐温80对水稻秸秆同步糖化发酵产乙醇的影响。结果表明,酵母接种量能有效地提高发酵液中乙醇的产率。水稻秸秆同步糖化发酵生产燃料乙醇的适宜发酵工艺条件为：起始pH值为4．0～4．5,培养温度为32℃,接种量为12％,发酵时间12-24h。在此条件下,生成乙醇的浓度为1．4mg／mL,水稻秸秆原料的乙醇转化率达7．02％。     

乙酸预浸渍用于小麦秸秆蒸汽预处理生产纤维素乙醇

通过改进传统蒸汽爆破预处理方法,利用两步法对小麦秸秆进行预处理.在蒸汽爆破前加入乙酸溶液预浸渍,有效的提高了后续同步糖化发酵的水平.采用乙酸预浸渍气爆预处理后的整个草浆和固形物同步糖化发酵乙醇浓度分别达到25.Sg/L、30.6g/L,分别达到葡萄糖乙醇理论产率的77％、90％;相比传统气爆,草浆和固形物同步糖化发酵乙醇浓度分别仅为17.5g/L、29.2g/L,葡萄糖转化为乙醇仅分别达到理论产率的63％、85％.通过提高固形物浓度到20％,乙酸预浸渍气爆处理后的固形物同步糖化发酵乙醇浓度可达67.3g/L,达到葡萄糖乙醇理论产率的96％.乙酸预浸渍气爆预处理能有效的减少抑制物的生成,提高木质纤维素结构破坏程度以及糖的回收率.     

不同糖化玉米秸秆方法发酵乙醇的工艺研究

以玉米秸秆为原料,分别探讨了酶解糖化发酵乙醇和生物糖化发酵乙醇的效果。结果表明:纤维素酶糖化玉米秸秆发酵乙醇的最佳工艺条件为:纤维素酶量1 400 U/g DS,时间60 h,酵母接种量13%,发酵温度35℃。在此条件下,乙醇产率为0.144 g/g。黑曲霉糖化玉米秸秆发酵乙醇的最佳工艺条件:黑曲霉接种量13%,时间60 h,酵母接种量13%,温度35℃。在此条件下,乙醇产率为0.149 g/g。并对两种糖化发酵乙醇的方法进行了比较。     

乙醇及发酵废液预处理秸秆条件的研究

利用酒精厂的乙醇发酵废液对小麦秸秆进行预处理,处理液仍在本厂回收后再利用,这样有助于降低预处理成本,促进纤维素乙醇的发展。经实验,处理小麦秸秆的最佳条件为乙醇、杂醇油体积比为1∶1,处理温度110℃,处理时间为200min,处理后的秸秆酶解率达到83.3%,比直接酶解高出近50%,但由于纤维糖化液中抑制发酵成分的存在,使得发酵的酒精度只有6%左右。     

堆积糖化对玉米秸秆同步糖化固态发酵生产乙醇的影响

该文以玉米秸秆为原料,经蒸汽爆破预处理后接入Trichoderma reesei Rut C-40培养纤维素酶曲,将纤维素酶曲与汽爆秸秆混合堆积糖化后,接入酵母菌进行同步糖化固态发酵生产乙醇,通过Box-Behnken设计实验得到最适酶解工艺条件:酶曲/汽爆秸秆为1.2,温度46℃,pH值4.4,堆积糖化48h后酶解率可达到32.50%。将酶解糖化48h后的底物接入酵母菌,发酵96h后乙醇产率可达0.15g/g底物,较直接同步糖化发酵乙醇产率提高了9.3%。     

碱性过氧化氢预处理后汽爆玉米秸秆半同步糖化发酵生产乙醇

为了实现纤维素乙醇生产的"三高"(高浓度、高转化率和高发酵效率)指标,以复合预处理处理后的玉米秸秆为基质,探究其半同步糖化发酵工艺过程。通过对其高底物浓度预酶解过程特性考察,确定其最佳预酶解工艺为:在加酶量30 FPU/g干基质和50℃下,以15.6%(w/v)为起始基质浓度,在酶解12 h时补加相当于20%(w/v)初始基质浓度的干物料后继续酶解24 h。在最佳预酶解工艺基础上,探究了培养基成分和培养条件对乙醇发酵的影响,确定了发酵过程工艺:酵母提取物16 g/L、接种龄20 h、接种量0.6 g干菌体/L、发酵温度39℃和PEG4000 0.01 g/g干基质。在最佳的半同糖化发酵工艺下,发酵24 h后,乙醇产量达73.75 g/L,发酵效率为3.07 g/(L·h),转化率为61%。结果表明通过补料半同步糖化发酵过程可以实现高浓度和高发酵效率双重目标,这有利于推进纤维素乙醇生产的工业化发展。     

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