啤酒酵母融合株GR8发酵特性的初步研究

研究了啤酒酵母原生质体融合株GR8的主要发酵特性。以12°Bx麦芽汁为三角瓶发酵培养基,在12℃下发酵8d,融合株GR8的发酵度为66.5%,凝絮性(本斯值)为3.0mL;发酵液中的双乙酰、乙醛、高级醇和乙酸乙酯等风味物质的含量分别为0.0583mg/L、9.66mg/L、91.20mg/L和22.8mg/L。从主要发酵特性的指标和口感品评以及遗传稳定性的结果表明,融合株GR8是一株具有工业应用前景的啤酒酿造酵母菌株。     

双亲灭活的原生质体融合株啤酒酵母DR9-2的构建及其特性的研究

啤酒酵母菌株JW1-1发酵液中的双乙酰、总高级醇的含量较低,但发酵度较低,发酵液中的乙醛含量较高;啤酒酵母菌株NW7-45发酵度较高,发酵液中的乙醛含量较低,但发酵液中的双乙酰、总高级醇的含量较高.为了得到优良的菌株,以紫外线灭活的菌株JW1-1原生质体和热灭活的菌株NW7-45原生质体为亲本进行融合.经三角瓶发酵筛选,得到较优良的融合株DR9-2和DR9-24.其中融合株DR9-2以12°Bx麦芽汁为培养基,用500L的发酵罐在12℃下发酵,发酵11d发酵液的发酵度为69.5%,发酵液中的双乙酰、乙醛和总高级醇的含量分别为0.0124mg/L、7.70mg/L和61.88mg/L.从融合株DR9-2的主要发酵特性和啤酒口感品评的结果表明,该菌株在啤酒酿造工业中具有应用前景.     

低嘌呤酿酒酵母的ARTP法诱变育种

采用常压室温等离子体(ARTP)诱变育种系统对酿酒酵母菌株A、B分别进行诱变,选育诱变菌株发酵的啤酒用高效液相色谱(HPLC)法测定腺嘌呤、鸟嘌呤、黄嘌呤、次黄嘌呤的含量,4种嘌呤在1~16 mg/L的测定范围内,相关系数R20.999,具有良好的线性关系。实验结果表明:诱变酵母菌株A-3发酵啤酒中嘌呤含量为77.67 mg/L,比初始菌株A的101.64 mg/L降低23.6%;诱变酵母菌株B-4发酵啤酒中嘌呤含量为76.26 mg/L,比初始菌株A的96.84 mg/L降低21.3%。诱变菌株A-3、B-4进行连续传代10次并进行发酵啤酒实验,诱变菌株A-3、B-4的发酵性能、发酵啤酒中总嘌呤含量和啤酒品质保持稳定。这表明ARTP诱变方法选育低嘌呤酿酒酵母菌种是可行的。     

用分子生物学手段控制啤酒中乙醛含量的研究

以F718,R719为引物,以质粒pFA6a—kanMX4为模板进行PCR扩增,采用基因转化法获得1株乙醇脱氢酶Ⅱ基因突变型工业酿酒酵母。驯养后的突变株啤酒生产小试表明,突变株乙醛含量为5．386mg／L,比原菌株乙醛含量7．932mg／L有所降低;发酵液发酵结束时,双乙酰含量为0．058mg／L,比原菌株双乙酰含量0．034mg／L有所升高;突变株发酵度为63％,比原菌株66％略有降低。     

啤酒酵母原生质体融合株GR8的中试研究

啤酒酵母原生质体融合株GR8的中试表明:融合株GR8凝絮性较强(本斯值为3.0);以12oBx麦芽汁为培养基,用500L发酵罐在12℃下发酵15d,发酵度为69.6%;发酵液中的双乙酰、乙醛、总高级醇、乙酸乙酯和乙酸异戊酯的含量分别为0.0390mg/L,3.26mg/L,84.7mg/L,11.14mg/L和0.99mg/L。     

低产乙酸啤酒酵母菌株A12的选育及中试

以啤酒酿造生产菌株啤酒酵母JM-36为出发菌株,用甲基磺酸乙酯(EMS)诱变,用含浅蓝菌素的麦芽汁琼脂平板分离抗浅蓝菌素的突变株,在低温下发酵,以发酵液的乙酸、双乙酰、乙醛、高级醇、发酵度和凝聚性为筛选指标,得到1株发酵特性优良的菌株A12。以13°BX麦芽汁为培养基,用100L发酵罐在10℃下发酵14d,菌株A12发酵液的发酵度为68.2%,乙酸、双乙酰、乙醛和高级醇的含量分别为62.3mg/L、0.081mg/L、5.321mg/L和76.43mg/L。菌株A12的主要发酵特性优良且稳定,啤酒口感良好。     

紫外诱变及苯黄隆抗性处理选育低双乙酰啤酒酵母

将APV菌株经紫外线诱变后筛出苯黄隆抗性菌株,经实验室菌种分离、筛选、发酵及双乙酰驯养等步骤,筛选育出一株2#菌株,发酵双乙酰峰值为0.36mg/L,成品啤酒双乙酰含量为0.07 mg/L,真正发酵度为65.8%.     

低双乙酰啤酒酵母的选育

将APV啤酒酵母菌株在不同的双乙酰含量梯度培养基内培养，挑出抗双乙酰的变异菌株，经菌种分离、筛选、发酵及双乙酰驯养等步骤选育出一株7^#菌，11℃低温发酵，双乙酰峰值0．36mg／L，成品啤酒双乙酰含量0．06mg／L，真正发酵度66．1％。     

青岛啤酒酵母与高浓酵母筛选高浓酿造酵母融合亲株

以青岛啤酒酵母和高浓精酵母为供试菌株,筛选出生长良好的酵母,为选育具有青岛啤酒风味的高浓酵母做准备.比较了7株酵母不同糖类发酵、离子抗性、二氧化碳减重、发酵液风味品评等指标.结果表明:T1、T2和T3是传统的青岛啤酒发酵菌株,其发酵液口味符合青岛啤酒口味要求,且对Cu2+均不耐受;而G4和G6发酵减重试验和风味物质分析中的乙醛含量指标的评价均优于G5和G7菌株,且它们的发酵液的风味也接近青啤口味.因此,选择T1、T2、T3和G4、G6作100L酿造试验,进一步确定融合亲株.     

超声波诱变选育低双乙酰啤酒酵母的研究

降低啤酒酵母的双乙酰的合成水平,可缩短啤酒发酵周期,提高生产效率。为获得低双乙酰生成量的菌株,本研究对出发菌株S.Cerevisiae SH进行超声波诱变处理,通过苯磺隆抗性初筛和发酵复筛,筛选到4株发酵6 d的双乙酰生成量低于阈值(0.15 mg/L)的突变株,其中突变株SH-8的双乙酰生成量为0.092 mg/L,相比于出发菌株降低了61.8%。研究表明,突变株保持了出发菌株的优良性状并具有良好的遗传稳定性。     

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