纤维素酶产生菌黑曲霉的选育及其产酶条件的研究

进行优良纤维素酶高产菌株的选育,并研究其发酵条件.以黑曲霉菌株S1为原始出发菌株进行紫外诱变,经过单因素实验和正交实验优化突变菌株的产酶条件.获得一株高产纤维素酶黑曲霉(Aspergillus niger)菌株S12,其最佳产酶条件为:在pH6.0、培养温度28℃、培养时间96 h条件下;秸秆粉2.5 g、麦麸2.5 g、1%(NH4)2SO410mL.在此条件下,滤纸酶活力为3.79 IU/mL,羧甲基纤维素酶活力19.06 IU/mL,β-葡萄糖苷酶活力47.33 IU/mL,其酶活分别是原始菌株的1.20倍、1.70倍和1.13倍.     

利用纤维素原料生产柠檬酸菌株的筛选

从土壤中筛选分离到一株能利用纤维素原料产柠檬酸的黑曲霉菌株S。研究表明:预处理稻草为菌株适宜利用的纤维素原料;以3%预处理稻草为基质,菌株的发酵特性是发酵12h时CMCase活力达218.4U/mL,FPase活力达44.1U/mL,12h后酶活力下降;发酵60h产酸率达22%。通过对菌株的产酸驯化筛选和复筛,获得一株产柠檬酸性能稳定的菌株黑曲霉S6。黑曲霉S6可作为利用纤维素原料生产柠檬酸研究的出发菌株。     

同时蒸馏法提取艾叶挥发油及其抑菌性研究

采用同时蒸馏法提取艾叶挥发油,研究影响提取效果的单因素,并采用正交设计试验.结果表明各因素对提取效果影响程度依次为:D(蒸馏提取时间)>A(液料比)>B(物料粒径)>C(浸泡时间).正交试验最佳组合是A2B2C2D2,即粒径60目,液料比8:1(mL/g),浸泡10h后萃取8 h,得到挥发油2.94 g/kg.研究挥发油的抑菌活性,结果表明,对几种常见食品腐败微生物进行抑菌试验,黑曲霉最为敏感,在浓度为100 μg/mL完全抑制.对常见的植物病原菌进行毒力测试,辣椒疫霉最敏感,EC50为95.0 μg/mL.     

产葡萄糖氧化酶黑曲霉的诱变选育及葡萄糖酸钙发酵条件的研究

用紫外线和钴60放射线照射对产葡萄糖氧化酶的黑曲霉菌株P-9进行诱变,以含有2-脱氧-D-葡萄糖的选择培养基进行筛选,共获得7个耐受菌株.其中产酶活性最大的U-69菌株的葡萄糖氧化酶活力是出发菌株P-9的2.5倍.研究了U-69菌株合成葡萄糖酸钙的发酵条件,结果显示,最佳发酵条件为葡萄糖150g/L,碳酸钙400g/L,硫酸铵3～4g/L,pH 5.5,250mL三角瓶装30mL发酵液,接种量10%,30～34℃发酵18h.     

黑曲霉产木聚糖酶的特性

研究了木聚糖酶产生菌黑曲霉(A.niger)238的产酶特性和麸曲的浸提条件,并对其浸提酶液进行浓缩.结果表明,菌株黑曲霉(A.niger)238产木聚糖酶受诱导物的影响,发酵时间在68～72h期间达到产酶高峰,酶活力为286U/mL.最佳氮源为(NH4)2SO4,装料量为每瓶10g,接种量为每瓶0.3mL.其发酵麸曲用固液比为1∶5的2g/dLCaCl2溶液,30℃浸提1.5h;浸提液采用25℃,40kPa,冷却水温度18℃条件超滤浓缩可获得90%以上回收率.     

南极假丝酵母脂肪酶B在黑曲霉中的分泌表达及其硅藻土固定化应用

为提高南极假丝酵母脂肪酶B（Candida antarctica lipase B,CALB）表达量,根据黑曲霉（Aspergillus niger）密码子偏好性设计合成CALB基因,以PnaII/tpi为启动子构建CALB表达载体并转化到黑曲霉HL-1中表达,摇瓶发酵120 h后上清液中重组CALB活力为171 U/mL。研究重组CALB的酶学性质,最适反应温度和pH值分别为50 ℃和8.0,在pH 6.0～9.0和45 ℃以下具有较高的稳定性,10 mmol/L Cu2＋、Zn2＋和0.1 g/100 mL十二烷基硫酸钠强烈抑制酶活力,而1 mmol/L Ca2＋、0.1 g/100 mL山梨醇对酶活力具有非常明显的激活作用。此外,以硅藻土为载体固定CALB,固定化酶活力为187 U/g。将制备的硅藻土-CALB固定化酶用于生物合成己酸乙酯,经反应条件优化后在无溶剂体系中己酸乙酯产率达91%。     

黑曲霉固态发酵生产亚麻脱胶用复合酶的研究

以麸皮为培养基主要原料,采用单因子和正交试验对黑曲霉HYA4固态发酵生产亚麻脱胶用复合酶的培养基以及培养条件进行了优化,结果表明,最适培养基组成为麸皮10g、豆粕添加量2.5%、NaNO33.5%、(NH4):SO41.0%、加水量10mL:最适发酵条件为:250mL三角料10g、起始pH/值5.0～5.5、培养温度32%、培养时间为96 h.工艺优化后果胶酶和木聚糖酶活力分别可达2215.48 U/g干曲,99.68U/g曲.     

黑曲霉利用菠萝皮培养基发酵产果胶酶的研究

为了摸索菠萝皮综合利用的新途径,对以菠萝皮为主要碳源和诱导物的黑曲霉果胶酶发酵进行了初步研究.结果表明,在菠萝皮最佳用量的培养基中,硫酸铵为最佳无机氮源,适量添加麸皮、Mg2+、Ca2+以及Tween-20对产酶具有促进作用.本次试验确定培养基主要组分为:菠萝皮粉60 g/L,麸皮12.5 g/L,(NH4)2SO4 20 g/L,NaH2PO4 10 g/L,MgSO4·7H2O 1g/L,CaCl2 1.1g/L,Tween-20 3 g/L:以此培养基进行发酵,最高果胶酶活力可达76818 U/mL.     

黑曲霉mAn-1产木聚糖酶液体发酵工艺的研究

对高产木聚糖酶黑曲霉mAn-1的液体发酵工艺进行优化,以提高其生产木聚糖酶的能力.采用单因素轮换试验分别优选出最适碳源种类和氮源种类,通过2水平正交试验设计对影响产酶的8个培养基组成成分进行效应评价,选择具有显著效应的2个因素,并确定出最适培养基组成:玉米芯粉25g/L,麸皮粉25g/L,NH4NO35g/L,KCl 0.5g/L,K2HPO4lg/L,MgSO4·7H2O 0.5g/L,微量元素液10mL,吐温-8010mL,CaCO320g:采用响应面中心组合设计试验对发酵条件进行优化,得出接种种龄、接种量和装液量的最佳值分别为49.3h、14.38mL、138mL.以优化后的工艺进行发酵,黑曲霉mAn-1的木聚糖酶活力可达8244U/mL.     

苦荞麸乙醇粗提物各极性成分的抗氧化活性研究

目的:寻找苦荞麸乙醇粗提物中抗氧化活性最强的部分,为分离该部分的有效成分提供参考.方法:以营荞麸为原料,用95％乙醇提取苦荞麸总黄酮粗提物;水悬浮,乙酸乙酯、正丁醇萃取,测定各萃取相以及苦荞麸总黄酮粗提物的总酚和总黄酮含量;通过DPPH·的清除能力、ABTS·+的清除能力、总还原力以及抑制β-胡萝卜素褪色能力的测定,比较不同萃取相和粗提物的抗氧化性.结果:乙酸乙酯相的总酚和总黄酮含量最高,抗氧化活性最强.乙酸乙酯萃取物的DPPH·清除能力(EC5078.86 μg/mL)优于芦丁(EC50135.71 μg/mL),弱于VC(EC5071.26 μg/mL);ABTS·+清除能力(EC5029.79 μg/mL)优于芦丁(EC5072.96 μg/mL)和VC (EC50112.71 μg/mL),还原力高于芦丁和槲皮素,抑制β-胡萝卜素褪色的能力(EC50101.24 μg/mL)低于BHT(EC5015.80 μg/mL).苦荞麸粗提物和萃取物的总酚和总黄酮含量与DPPH·和ABTS·+清除率EC50值呈负相关性.结论:乙酸乙酯萃取物具有很强的抗氧化活性,优于粗提物.据此分离苦荞麸乙醇粗提物乙酸乙酯相的抗氧化成分.     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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