嗜杀酵母发酵苹果酒的研究

对筛选得到的S1嗜杀酵母,通过单因素试验和正交试验确定其最佳发酵苹果酒工艺条件,结果表明,糖度25%,酸度2 g/L,发酵温度为20℃,接种量6%为其最佳工艺条件.发酵果酒澄清透明、具有苹果香气、酒体醇厚,酸甜协调.S1嗜杀酵母分泌的嗜杀毒素的活力与发酵温度和发酵基质pH值有关,在25℃、pH 4.2时毒素活力最高.(孙悟)     

腐烂苹果中嗜酸耐热菌(Alicyclobacillus acidoterrestris)的分离鉴定及生长特性的初步研究

从金帅腐烂苹果中分离嗜酸耐热菌,进行形态学特征、生理生化特性、16S rDNA区鉴定,研究了温度、pH值对其生长的影响及芽孢耐热性。结果表明:分离得到了2株嗜酸耐热菌A-1与A-2,均为脂环酸芽孢杆菌属的酸土脂环酸芽孢杆菌,适生长温度均为45℃,适生长pH值分别为4.0、3.5;A-1、A-2芽孢的D90℃分别为11.90 min和13.70min,A-2表现出更强的耐热性。     

酱香型酒糟醅酵母菌的初步分类及选育

对酱香型酒糟醅中的酵母菌进行了初步分类和优育酵母菌株的选育,结果表明:①酱香型酒糟中的酵母可分为5类,以2类和3类酵母最多,其次是4类酵母,1类和5类酵母均很少.②从3类酵母中选育出了5株发酵力强的菌株,其中5S26和5S32耐酒精能力达19%vol,5S4在温度为46℃水浴中处理48h,仍能良好地生长.③选育出的5S32酵母在主要酿酒原料(玉米、高粱、大米、红薯和小麦)糖化液中均表现出较强的发酵力.     

发酵醋醅酵母菌的分离、生长特性及分子鉴定

从山西老陈醋发酵醋醅中分离纯化出2株酵母菌,编号分别为YW与YR-1.通过YW与YR-1在不同温度和pH值条件下的培养,采用浊度法测定培养菌液OD600值,确定最适生长温度与pH值,结果表明菌株YW最适生长温度为30℃,最适生长pH值为6.5;菌株YR-1最适生长温度为28℃,最适pH值为7.0.对菌株YW,YR-1的核糖体ITS+5.8S rDNA区的克隆与测序,获得菌株YW与YR-1的ITS+5.8S rDNA片段长度分别为607bp与602bp,序列已提交至Genbank(登录号为JX205095和JX205094).通过在Genbank数据库BLAST以及与亲缘关系较近模式菌株构建分子发育树,表明YW属于毕赤酵母属(Pichia),与Pichia guilliermondii亲缘关系最近,命名为Pichia guilliermondii YW; YR-1属于掷孢酵母属(Sporobolomyces),与Sporobolomyces camicolor亲缘关系最近,命名为Sporobolomyces carmicolor YR-1.     

白乌鱼胴体粘液中耐热菌的耐热性及特征菌种鉴定

为了进一步分析白乌鱼胴体粘液中特征微生物的耐热性,并对其中的特征菌进行鉴定,本文对白乌鱼胴体粘液进行了热处理,然后对热处理粘液中的特征菌进行了分离纯化,并对其种属进行了鉴定。通过比较热处理后白乌鱼胴体粘液的外表特征、耐热性、特征菌的形态特征、特征菌的生长曲线和特征菌S3的耐高热性,发现新鲜白乌鱼胴体粘液呈淡红色,随着处理温度的升高逐渐呈淡绿色;接种了30℃热处理粘液的培养基有三种菌落(S1、S2和S3),接种了50℃热处理粘液的培养基有S2和S3两种菌,而接种了70℃、90℃和煮沸处理粘液的培养基,只生长了S3菌,空白组中无菌落生长。进一步对S1、S2和S3菌进行分析,得出S1为革兰氏阴性菌,S2和S3为革兰氏阳性菌;菌株S3在105℃高压灭菌锅中处理20 min之后仍能存活;菌株S2、S3分别在培养14 h、16 h时达到生长高峰;通过16S rDNA序列测序,发现菌株S1属于不动杆菌属(Acinetobacter sp.),菌株S2属于嗜根考克氏菌属(Kocuriarhizophilasp.),菌株S3属于芽孢杆菌属(Bacillussp.)。因此,白乌鱼胴体粘液中的耐热菌为枯草芽孢杆菌(Bacillus subtilis)。     

优良发酵剂的筛选鉴定及菌株生长条件优化的研究

从泡菜中分离出菌株,利用钙溶圈筛选乳酸菌。经低温发酵能力测试筛选出优良菌株并接种于鸡肉发酵验证,得到发酵特性优良的菌株三株。根据生化鉴定和16S rDNA序列测序所得菌株为两株乳杆菌(Lact.1、Lact.2)和一株清酒乳杆菌(Lact.3)。以OD值为指标,以pH值、温度、葡萄糖添加量和接种量作为参考因素,利用正交试验优化确定两株乳杆菌(Lact.1、Lact.2)和清酒乳杆菌生长最优条件分别为pH7.0、温度35℃、葡萄糖添加量4%、接种量3%;pH7.0、温度35℃、葡萄糖添加量2%、接种量3%和pH6.0、温度32℃、葡萄糖添加量2%、接种量1%。     

利用细胞融合技术选育生产燃料乙醇的耐高温酵母

0前言 通常情况下,酵母的最佳发酵温度介于25-30℃之间.在高温状态下,酵母生长所需的酶活性降低,从而降低生长率.在南方省区,夏季温度通常会超过35℃,在无冷却系统情况下,由于代谢过程的放热反应可导致温度上升,发酵罐温度可能超过40℃,严重影响酒精产率.在一些酒精生产企业,喷淋冷水于发酵罐可以部分克服高温问题,但是会增加生产成本[1],选育耐热性菌株可以解决这一问题[2].另外,利用耐热菌株高温条件下发酵还可以降低染菌的机会.     

产酯酵母的筛选及其发酵特性研究

从大曲中筛选到8株产酯酵母,选酶活最高菌株进行26S rDNA鉴定,确定其为异常毕赤酵母.试验结果表明,该酵母麸曲的酯化力可达到19.36 mg/100 mL.该菌株麸曲最佳培养时间为6d;液体培养最高耐受温度为43℃;最低耐受pH值为3.5;最高耐受酒精度为18 ％vol;最适生长温度为27℃;利用葡萄糖产酒精能力较低.     

响应面法优化无核白甜葡萄酒酿造工艺研究

以无核白葡萄为原料,利用响应面分析方法,建立无核白甜葡萄酒酒精度(Y_1)、感官指标分值(Y_2)与酵母接种量(X_1)、初始糖度(X_2)、初始pH值(X_3)和发酵温度(X_4)的数学二次多项回归方程模型,分析得到无核白甜葡萄酒发酵工艺最优条件:酵母接种量X1=5.6%、初始糖度X_2=23.11%、初始pH值X_3=3.54和发酵温度X_4=20.16℃,无核白甜葡萄酒酒精度为11.8%vol,感官指标分值为94.17。用此工艺参数酿造的无核白甜葡萄酒呈禾秆黄色,澄清透亮,无悬浮物和沉淀,具有浓郁的葡萄果香,酒香怡人,醇厚柔和,回味绵长。本研究为我区无核白葡萄产业提供技术支撑。     

含醇发酵乳工艺研究

筛选了一株产CO2能力较强的酒精酵母，研究了以脱脂乳为原料，以乳酸菌和酒精酵母混合发酵制备含醇发酵乳饮料的关键工艺条件。结果表明：选用编号为1515的酒精酵母，采用分步发酵工艺，乳酸菌接种量为5%（L.b：S.t=1：1），发酵温度为42℃，时间为4.5h，酵母接种量为1.5%，发酵温度32℃，时间20h，在上述的条件下，可获得溶液粘稠、均一稳定、酸味适中，有酵母发酵醇香味，口感较好的含醇发酵乳。     

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.     

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.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

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.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

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