微波与纤维素酶协同水解杨木制备还原糖的研究

以速生杨木为原料,采用微波辐射和纤维素酶协同水解制备还原糖.探讨了经过微波辐射处理后原料的粒度、酶液用量、水解温度和水解时间对还原性糖得率的影响,并采用响应面法建立二次回归模型对水解工艺进行了优化,在反应温度为50.5℃、反应时间为20.7h、酶液用量为27U/g时,还原糖的得率可达到32.40%.比在相同工艺条件下未经微波处理的得率提高了11.87%.     

超声波诱导降解花生壳制备还原糖的研究

以花生壳为原料,采用超声波和NaHSO4.H2O固体酸水解制备还原糖。探讨超声波功率、反应时间、反应温度、固体酸用量对还原糖得率的影响。采用响应面法建立二次回归模型,并对水解工艺进行优化。研究结果表明,反应温度61.77℃,固体酸用量5.88%和反应时间124.14 min,还原糖的得率可达到80.72%,比在相同工艺条件下未经超声波协同处理的得率提高了27.38%。     

微波固体酸联合水解棉籽壳制备还原糖的研究

以棉籽壳为原料,采用微波和固体酸协同水解制备还原糖。探讨了微波功率、固体酸用量、反应时间、反应温度、液固比对还原性糖得率的影响。采用响应面法建立二次回归模型,并对水解工艺进行了优化。研究结果表明,当微波功率461.91W,固体酸用量6.46%,反应时间2.99h,反应温度100℃,液固比为18∶1时,还原糖的得率可达到62.49%。     

超声波辅助碱法制备玉米芯木聚糖

以玉米芯为原料,经高温预处理后,采用超声波辅助碱法提取玉米芯木聚糖,在单因素实验的基础上,通过正交试验对玉米芯木聚糖提取工艺进行优化。结果表明:木聚糖的最佳制备工艺为氢氧化钠浓度7%,料液比1∶25,超声功率250 W,超声时间40 min,超声温度60℃。在此条件下,提取液中以玉米芯计还原糖的含量为64.10 mg/g,可溶性总糖含量为100.14 mg/g,木聚糖得率为9.01%。     

微波辅助稀酸降解玉米芯的工艺优化及其效果研究

为提高木质纤维素的利用率及经济效益,以稀酸为催化剂,采用微波辐射相结合的方法对玉米芯进行水解研究。以还原糖得率和原料转化率为指标,通过单因素试验和正交试验考察微波辐射时间、微波功率、酸浓度、固液比和秸秆颗粒大小等对玉米芯水解的影响,利用扫描电镜(SEM)和红外光谱(FT-IR)分析原料及不同方法处理后的水解残渣。结果表明,微波辐射稀酸催化玉米芯水解的最佳工艺条件为:玉米芯粉碎至60~80目,常压,固液比1:8(g/mL),酸浓度13%,微波功率130 W,反应时间20min,该条件下还原糖得率为66.41%、原料转化率为52.70%。SEM及FT-IR分析表明微波辅助稀酸的降解效果较好,反应后玉米芯的表面结构遭到了严重的破坏,其半纤维素基本被水解,同时也有部分纤维素被水解。     

WO3/ZrO2固体酸预处理玉米芯制备木糖醇的效果研究

以玉米芯为原料,采用WO3/ZrO2固体酸进行预处理,然后发酵制备木糖醇。探讨了预处理温度、预处理时间、固体酸用量及液固比对木糖醇得率的影响。采用响应面法建立二次回归模型,并对预处理工艺进行了优化。研究结果表明固体酸预处理能有效的促进玉米芯降解,提高木糖醇的得率。当预处理温度为110.76℃、预处理时间为60.71 min、固体酸用量为4.14%时,木糖醇的得率比相同条件下未进行固体酸预处理的试样提高了25.21%。     

酸预处理—酶水解法从木薯秆中提取糖的研究

研究了"酸预处理-酶水解"提取法从木薯茎秆中提取糖的工艺及效果,对比了盐酸和甲酸的预处理效果和酶水解条件对还原糖产率的影响.研究结果表明:盐酸预处理的效果优于甲酸预处理,在合理的实验条件下,相对于木薯秆绝干原料质量的最高还原糖得率为26.1%.     

稀酸预处理玉米芯酶解工艺响应面优化研究

木质纤维原料还原糖（葡萄糖、木糖）转化是燃料乙醇生产的关键步骤之一,该文以玉米芯为原料,采用稀硫酸处理、酶水解以提高还原糖转化量。以还原糖转化量为考核指标,采用单因素试验及响应面试验设计优化稀酸处理玉米芯酶解条件,拟合硫酸体积分数、加酶量、酶解时间3个因素对还原糖转化量的回归模型。结果表明,最佳酶解工艺为121 ℃条件下预处理60 min,硫酸体积分数0.8%,料液比1∶15（g∶mL）,加酶量7%（纤维素酶∶半纤维素酶1∶1）,酶解时间70.9 h。在此最佳条件下,采用高效液相色谱（HPLC）法测定酶解液中还原糖转化量为462.62 mg/g,其中木糖、葡萄糖转化量分别为330.02 mg/g、132.60 mg/g,还原糖转化率可达46.3%。     

超声波辅助复合酶法制备玉米芯低聚木糖

以玉米芯为原料,采用超声波辅助复合酶法制备低聚木糖。在单因素试验的基础上,通过正交试验对超声波辅助复合酶法制备玉米芯低聚木糖工艺进行优化。结果表明,低聚木糖的最佳制备工艺条件为超声温度60℃,超声功率300 W,由木聚糖酶和纤维素酶按照3:2的比例组成复合酶添加量1.0%,酶解20 min,料液比为1:15(g/mL)。在此条件下,酶解液中以玉米芯计还原糖含量为43.61 mg/g,可溶性总糖含量为75.01 mg/g,平均聚合度为1.72。     

不同原料酶法制备低聚木糖的研究及成分分析

对木聚糖酶的酶学特性进行了研究,同时以甘蔗渣、玉米芯、麸皮、啤酒槽为原料酶解制备低聚木糖并对其酶解液的还原糖含量和主要成分进行了分析。结果表明:该木聚糖酶的最适反应温度为60℃,最适反应pH为5.0;同时在温度为40～60℃和pH为6的情况下,木聚糖酶具有较好的稳定性。在最佳酶解条件下,采用木聚糖酶酶解甘蔗渣、玉米芯、麸皮、啤酒槽中的木糖,通过测定酶解液中的还原糖含量以分析木聚糖的水解度,结果表明,麸皮中木聚糖的水解度最高,为21.19mg/mL;其它依次为啤酒糟、玉米芯、蔗渣。采用高效液相色谱法对4种不同原料的木聚糖酶水解产物进行分析,结果显示:啤酒糟的酶解产物中木二糖和木三糖的相对含量最高,分别为13%、26.7%,其他依次为玉米芯、麸皮、甘蔗渣。     

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