基于麦汁培养基的富硒酵母培养条件优化

以啤酒酵母为材料,对富硒酵母的最适培养条件进行研究。结果显示：以2oBx 的麦汁培养酵母菌,其生长得率最高,过高的麦汁质量浓度会产生克拉勃脱效应而影响酵母生长。在2oBx 的麦汁培养基中适当添加酵母提取物,可显著提高酵母的生物量,而添加硫酸铵和磷酸二氢钾对酵母生物量的提高不明显;添加葡萄糖在一定程度上也能增加酵母的生物量,但这种增加会被硫酸铵抑制。培养基中的初始硒含量能显著影响酵母的生物量和细胞中硒的积累,在初始质量浓度为10mg/L(最终质量浓度为50mg/L)的Na2SeO3 初始质量浓度下培养24h,酵母的生物量可达2.83g/L,细胞中积累的总硒量为266.3mg/kg。     

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.     

富硒酵母发酵工艺的优化

以富硒酿酒酵母（Saccharomyces cerevisiae）SY2为发酵菌种,利用5 L发酵罐培养富硒酵母。以富硒酵母生长及硒转化率为评价指标,优化其发酵工艺条件,比较溶氧反馈补料与拟指数补料两种方式对富硒酵母生长、硒转化率等的影响。结果表明,富硒酵母最适发酵条件为：初始pH 5.0,发酵温度30℃,接种量8%,硒添加量30 mg/L,发酵时间24 h。在此优化条件下,富硒酵母生物量为9.8 g/L,硒转化率为77.5%。在拟指数补料方式下,培养周期为34 h,富硒酵母得率为0.252 g/g,硒含量为1 920.5μg/g,硒的转化率为82.7%;在溶氧反馈补料方式下,培养周期为46 h,富硒酵母得率为0.317 g/g,硒含量为1 759.5μg/g,硒转化率为90.1%。结果显示,拟指数补料培养周期短,生产强度、酵母硒含量较高,是适宜补料方式。     

产朊假丝酵母富硒及产谷胱甘肽的培养工艺

为生产高生物活性(高谷胱甘肽、高有机硒含量)的富硒产朊假丝酵母,在100 L发酵罐规模水平研究了菌体培养、无机硒的添加工艺,结果表明指数连续流加是富硒酵母最佳的培养方法,在补料的同时添加125 mg/L的无机硒(Na_2SeO_3)和3 mmol/L的半胱氨酸,菌体浓度、胞内谷胱甘肽浓度及无机硒转化率分别达到72 g/L、1080 mg/L和86%,胞内有机硒含量达到1493 μg/g,研究结果对富硒酵母大规模工业化生产具有一定的实践指导意义。     

不同添加时间和添加量组合对酵母富硒效果的影响

以亚硒酸钠为硒源,在酵母的培养过程中,于不同的时间组合添加不同量的亚硒酸钠,以研究不同添加时间和添加量对酵母富硒的影响。实验结果表明:在发酵过程中的5h、8h、11h,添加一定量的亚硒酸钠使其在发酵液中的浓度分别达到5mg/L、10mg/L、15mg/L时,酵母的产量和富硒效果最佳。     

硒浓度对小球藻生长、生物富集的影响

研究了硒浓度对小球藻生长的影响,以及硒浓度对小球藻生物富集的影响,并对相关的可能机理进行了讨论.研究发现,高浓度的硒对小球藻生长具有抑制作用,当硒浓度超过1mg/L时会产生抑制作用;当硒浓度增至12mg/L时,发现藻细胞生长几乎停止.小球藻对硒的生物富集随着硒浓度的增加而增加,硒浓度为1mg/L时,藻体的硒含量为9.92μg/g;当硒浓度为8mg/L时,藻体的硒含量达到了83.66μg/g.小球藻富硒培养较适宜的硒添加浓度是4mg/L～8mg/L.     

产朊假丝酵母富硒及产谷胱甘肽的培养工艺

为生产高生物活性（高谷胱甘肽、高有机硒含量）的富硒产朊假丝酵母,在100 L发酵罐规模水平研究了菌体培养、无机硒的添加工艺,结果表明指数连续流加是富硒酵母最佳的培养方法,在补料的同时添加125 mg/L的无机硒（Na₂SeO₃）和3 mmol/L的半胱氨酸,菌体浓度、胞内谷胱甘肽浓度及无机硒转化率分别达到72 g/L、1080 mg/L和86%,胞内有机硒含量达到1493 μg/g,研究结果对富硒酵母大规模工业化生产具有一定的实践指导意义。      

硒酸精氨酸培养富硒酵母的条件优化

以硒酸精氨酸(ASe)为有机硒源,对酿酒酵母的富硒培养条件进行了优化研究.采用单因素方法优化转速、pH、温度、接种量、装液量和培养基种类;SAS响应曲面法优化富硒培养基.称重法测定生长曲线,原子荧光光度计测定硒含量.优化后酿酒酵母的硒产量为1189.662μg/L,比优化前提高近4.2倍.     

极大螺旋藻培养及生物富硒条件的优化

为获得高富硒量的极大螺旋藻,在硒添加方式为8d等量多次添加800μg/mL Se(Ⅳ)的前提下,通过单因子试验研究了初始pH值、光照强度、NaHCO3浓度和NaNO3浓度对富硒极大螺旋藻生物量和硒富集效果的影响.在光照20001x∶50001x= 12h∶ 12h条件下,通过L9 (34)正交试验确定了NaHCO3浓度12.8g/L、NaNO3浓度2.5g/L、pH值9.8为极大螺旋藻生物富硒的最佳条件,得到了生物量为2.517g/L,总硒含量为2.843mg/g(干重)的富硒极大螺旋藻.     

富硒大豆蛋白的研制

以黄豆芽为富硒载体,采用喷淋和浸泡相结合的方式添加不同浓度的硒溶液,通过黄豆的发芽过程实现对硒元素的生物富集,制备出富硒黄豆芽并分离得到富硒大豆蛋白.结果表明:当硒培养液浓度为10μg/mL、培养时间为120h时富硒效果最佳,制备出的富硒大豆蛋白富硒量为21.23μg/g.富硒大豆蛋白与普通大豆蛋白相比,氨基酸含量有明显提高,其中谷氨酸的含量提高最为显著,大约提高了35%.     

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