硒对啤酒酵母细胞生长的影响

目的研究不同硒浓度对啤酒酵母细胞生长的影响，确定适宜的硒添加量。方法用分光光度计测定不同硒浓度时酵母细胞培养液在不同时间的吸收度，绘制生长曲线，比较硒浓度不同时酵母细胞的生长情况。结果亚硒酸钠的添加浓度小于20μg／mL时，有促进酵母菌生长的作用；亚硒酸钠浓度高于30μg／mL时，对酵母菌生长有明显的抑制作用；亚硒酸钠浓度在20μg／mL时酵母菌可以正常生长。结论亚硒酸钠的添加浓度应在20μg／mL左右。     

硒对啤酒酵母生理代谢活动的影响

测定了不同硒离子浓度下啤酒酵母细胞的生长曲线、干重以及培养基中的pH值、总酸、还原糖的变化趋势。结果表明,当亚硒酸钠的添加浓度小于20!g/mL时,硒对酵母菌的生理代谢活动有促进作用;当硒浓度高于30“g/mL时,对酵母菌的生理代谢活动有明显的抑制作用,因此硒的添加浓度应在20#g/mL左右。     

富硒益生菌的筛选及其富硒条件的优化

为了获得能耐受较高亚硒酸钠质量浓度和具有富硒能力的益生菌菌株,对7株酵母菌和12株乳酸菌进行了筛选。结果表明,所有菌株均能在亚硒酸钠质量浓度为20~80μg/m L的平板上生长,乳酸菌YQRS菌株和酵母菌FJYJM3菌株具有较高的耐受性和富硒能力。对它们进行发酵条件的优化,表明YQRS菌株在亚硒酸钠添加量为15μg/m L、添加硒的时间为对数期前期时,富硒效果最好,菌体生物量为2.66 g/L,总硒含量能达到2 300.26μg/L。而FJYJM3菌株在亚硒酸钠添加量为20μg/m L,添加硒的时间为对数期前期时,富硒效果最显著,生物量能达到4.86 g/L,总硒含量能达到5 790.99μg/L。     

红发夫酵母富硒特性研究

通过摇瓶实验,研究了红发夫酵母在蛋白胨、尿素、硝酸铵、硫酸铵、硝酸钾、氯化铵等氮源中的生长、色素合成和硒富集情况,探讨了亚硒酸钠浓度对细胞生长和色素合成的影响、培养基pH对细胞生长和硒富集的影响、亚硒酸钠添加时机对色素合成和硒富集量的影响。结果表明,在硝酸铵为氮源的培养基中,细胞生长最慢;在尿素为氮源的培养基中,可以获得色素含量和硒富集率分别为530.4μg/g和93.2%的细胞;培养基中添加10mg/L亚硒酸钠对细胞生长和色素合成影响最小;对细胞生长和硒富集而言,适宜的pH是4.5～5.0;在培养进行到第8～16h添加10mg/L的亚硒酸钠,细胞中有较高的色素含量和硒含量。     

硒对杏鲍菇菌丝生长的影响

通过在液体培养基中添加亚硒酸钠,研究硒对杏鲍菇菌丝生长的影响.结果表明:当硒的浓度为0～ 30μg/mL时,杏鲍菇的生物量、多糖含量、蛋白质含量均呈增加趋势,且浓度在30μg/mL时,含量为最大;当浓度超过30μg/mL时,表现出抑制作用.硒在菌丝内的积累量在30μg/mL时为最大.     

硒对杏鲍菇菌丝生长的影响

通过在液体培养基中添加亚硒酸钠,研究硒对杏鲍菇菌丝生长的影响。结果表明:当硒的浓度为0～30μg/mL时,杏鲍菇的生物量、多糖含量、蛋白质含量均呈增加趋势,且浓度在30μg/mL时,含量为最大;当浓度超过30μg/mL时,表现出抑制作用。硒在菌丝内的积累量在30μg/mL时为最大。      

亚硒酸钠对蛋白核小球藻生长及生物转化的影响

本文研究了亚硒酸钠对海水培养蛋白核小球藻的生长和有机硒转化能力的影响,以及富硒蛋白核小球藻中的主要硒形态。通过分批等量添加2μg/mL至50μg/mL的亚硒酸钠,确定最佳富硒培养浓度,并采用高效液相色谱法检测藻体中亚硒酸钠、硒代半胱氨酸和硒代蛋氨酸三种主要硒形态的含量。结果表明:亚硒酸钠浓度不宜过高,否则蛋白核小球藻的生长受到抑制。硒浓度为2μg/mL时小球藻的生物量较高,有机硒含量达到301.40μg/g,占总硒含量的83.24%;高效液相色谱分析表明在该培养条件下富硒小球藻中有机硒的主要形态为硒代半胱氨酸和硒代蛋氨酸;在测定的三种主要硒形态中未转化的亚硒酸钠仅占23.02%。上述结果说明在海水培养下,小球藻富硒培养的适宜外加硒浓度为2μg/mL,此条件下长势良好,无机硒得到有效转化,有机硒含量较高,可达到富硒要求。     

不同红曲菌菌株耐硒能力和富硒能力的初步研究

为比较不同红曲菌菌株的耐硒能力和富硒能力，以5株红曲菌菌株为研究对象，通过接种于亚硒酸钠浓度为0、10、20、50、100、200μg/mL的PDA培养基中培养，测量其生长曲线和菌丝体中硒含量和总硒产量。结果显示：不同亚硒酸钠浓度对红曲菌菌株生长的影响与硒的富集均存在差异，其中耐硒能力最强的菌株为紫色红曲菌CICC 5046，其在亚硒酸钠浓度为50μg/mL的PDA培养基平板上培养15 d后菌落直径可达(53.8±1.5)mm；富硒能力最强的菌株为红色红曲菌M7，其在亚硒酸钠浓度为50μg/mL的PDA培养基平板(25 mL培养基)上培养15 d后总硒产量达到最高，为(124.43±2.01)μg；而当PDA培养基中亚硒酸钠浓度为200μg/mL时，红色红曲菌M7菌丝体中的硒含量达到最高，为(3120.59±193.63)μg/g。因此，不同红曲菌对亚硒酸钠的耐受能力和富集能力均不同，这种差异性可能与菌株的基因型或其抗氧化能力有关。     

提高产朊假丝酵母富硒能力的工艺条件研究

在5L发酵罐水平上研究不同培养条件对富硒产朊假丝酵母细胞生长、谷胱甘肽合成和富硒能力的影响,通过分批发酵试验确定较优的培养方案:在发酵培养的第18小时加入20mg/L亚硒酸钠,发酵罐转速450r/min,L-蛋氨酸的添加浓度10mmol/L.该条件下,酵母细胞干重为11.32g/L,胞内谷胱甘肽和有机硒含量分别达到11.5mg/g和1352μg/g,该方案为高性能(高胞内谷胱甘肽含量、高有机硒含量)富硒产朊假丝酵母的高效制备奠定了基础.     

灵芝液体发酵富集硒元素研究

研究了灵芝在亚硒酸钠水平分别为50μg/mL、100μg/mL、150μg/mL、200μg/mL、250μg/mL、300μg/mL、350μg/mL、400μg/mL的固体PDA培养基上的生长情况,30℃恒温培养6d,观察并测定菌落直径;在不同亚硒酸钠浓度条件下进行液体发酵,180r/min转速下30℃摇床培养5d,检测发酵液生物量、富硒率,同时检测富硒后菌丝体部分金属元素的含量变化。结果表明:150μg/mL~250μg/mL的含硒固体PDA培养基上菌丝体生长好,在含硒250μg/mL液体发酵培养基上菌丝体生物量最高为0.86g,300μg/mL发酵液中富硒率最高为47.71%,而且富硒后的菌丝体其他金属元素含量变化不明显。     

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