襄阳大头菜不同发酵状态腌制液中细菌多样性分析

利用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)研究襄阳大头菜正常发酵腌制液与长膜腌制液的细菌多样性,并对优势条带进行测序构建系统发育进化树。结果显示:在两个不同状态发酵液中的优势菌属均为Halomonas属、Halanaerobim属、Chromohalobacter属、Lentibacillus属、Psychrobacter属、Salicola属和不可培养的Stenotrophomonas属细菌,大头菜正常发酵腌制液与长膜腌制液在DGGE指纹图谱上没有明显差异。对DGGE指纹图谱进行UPGMA聚类发现,聚类的结果与腌制液的状态没有关系。由以上结果推断,襄阳大头菜腌制液长膜的机制与细菌关系不大。     

襄阳大头菜酱液中酵母菌多样性分析

对正常发酵襄阳大头菜酱液和长膜襄阳大头菜酱液中的酵母菌多样性进行研究。采用纯培养、形态学和26SrDNA基因序列分析法对正常发酵襄阳大头菜酱液和长膜襄阳大头菜酱液中的酵母菌进行多样性分析。从3份正常发酵襄阳大头菜酱液中分离13株酵母菌,其中2株Zygosaccharomyces属,3株Cystobasidium属,3株Erythrobasidium属,2株Acremonium属,1株Rhodotorula属,1株Bulleromyces属,1株Issatchenkia属。从3份长膜襄阳大头菜酱液中共分离7株酵母株,其中5株Zygosaccharomyces属,1株Yamadazyma属,1株Rhodotorula属。为了研究大头菜中酵母菌与已知酵母菌的进化关系,进行了系统发育树的建立和分析,20株酵母菌归属于2个门,10个属,与序列分析结果一致。正常发酵大头菜酱液中酵母菌多样性高于长膜大头菜酱液,Zygosaccharomyces属酵母菌为长膜大头菜中的优势菌株。     

襄阳大头菜腌制液膜醭细菌群落结构研究

使用Miseq高通量测序技术对3个襄阳大头菜腌制液膜醭样品的细菌微生物群落结构进行了解析。在门水平上,变形菌门（Proteobacteria）和硬壁菌门（Firmicutes）平均含量分别为62.12%和34.13%。在属水平上,相对含量＞1.0%的细菌属分别为盐单胞菌（Halomonas）、色盐杆菌属（Chromohalobacter）、海杆菌属（Marinobacter）、盐厌氧菌属（Halanaerobium）、四联球菌（Tetragenococcus）和碱杆菌属（Alkalibacillus）,其相对含量为26.31%、16.49%、8.13%、24.87%、6.13%和1.16%。在操作分类单元水平（OTU）上,发现14个平均相对含量＞1.0%的核心OTU,其中OTU4083（隶属于盐厌氧菌属）、OTU4400（隶属于色盐杆菌属）和OTU846（隶属于盐单胞菌属）的累计平均相对含量为39.50%。由此可见,襄阳大头菜膜醭中的细菌微生物主要由隶属于变形菌门和硬壁菌门的6个属构成,且膜醭共有大量的核心细菌菌群。     

不同地区产腌制大头菜产品品质的比较研究

在对理化指标、全质构和色度进行测定的基础上,同时结合多元统计学方法,对不同地区产腌制大头菜产品品质的差异性进行了探讨。通过方差分析(analysis of variance,ANOVA)发现襄阳大头菜和成武酱大头的L*和b*显著高于四川成都地区产大头菜(P0.05),而弹性、粘聚性、粘性、咀嚼度和回复性等质构指标呈现相反的趋势。值得一提的是,襄阳大头菜食盐含量最高,而成武酱大头具有最高的蛋白质、氨基酸态氮、还原糖和总酸含量。通过主成分分析(principal component analysis,PCA)、多元方差分析(multivariate analysis of variance,MANOVA)和聚类分析(cluster analysis,CA)发现虽然不同地区产腌制大头菜产品品质存在显著差异(P0.05),然而襄阳大头菜与成武酱大头产品品质更为相似,且与四川成都产大头菜有较大区别。     

低盐条件下CO_2置换对汉逊德巴利酵母生长及渍菜品质的影响

传统的渍菜盐渍是采用高盐保存的方式,其存在污染环境、高耗能以及营养流失等缺陷,在盐渍发酵中容易产生菌醭。本试验旨在研究低盐条件下CO_2置换对汉逊德巴利酵母生长及渍菜品质的影响。试验以7%的低盐量为基准,在置换CO_2的条件下,研究了压力、CO_2浓度、含盐量等对汉逊德巴利酵母生长生长的影响。结果表明,高浓度CO_2及其所形成的高压和高盐都影响了汉逊德巴利酵母生长的生长,延迟了汉逊德巴利酵母生长的对数生长期。渍菜在保存6个月期间微生物菌落总数、酸度、亚硝酸盐均明显下降,渍菜的硬度值和菜体的色泽却得到保持,腌渍液清彻透明。这表明,低盐条件下,CO_2置换对渍菜坯料的安全保存有积极促进作用,能够有效的控制杂菌的生长,为改善我国传统腌渍蔬菜的工艺提供了新的一条思路。     

盐渍白萝卜的真菌菌群结构DGGE分析及酵母菌分离鉴定

采用变性梯度凝胶电泳技术(denatured gradient gel electrophoresis,DGGE)对不同盐渍白萝卜样品的真菌菌群结构分析表明,Candida lactis-condensi、Candida versatilis、膜醭毕赤酵母(Pichia membranifaciens)、汉逊德巴氏酵母菌(Debaryomyces hansenii)为盐渍萝卜的优势菌。通过传统分离培养技术从样品中分离到17株酵母菌,通过分子生物学鉴定为Pichia sp.、膜醭毕赤酵母(Pichia membranefaciens)、德巴利酵母属(Debaryomyces sp.)。传统分离培养技术未分离到Candida lactis-condensi,Candida versatilis。DGGE技术能够快速高效、直观地反映盐渍白萝卜的菌群结构,结果合理。     

葡萄酒发酵过程中菌醭形成及防治方法的探讨

葡萄酒发酵过程中菌醭形成及防治方法的探讨黄亚东（江苏省食品学校发酵工程系；２２３００１）葡萄酒是一种营养丰富的饮料酒，汉逊酵母、毕赤氏酵母、假丝酵母等发酵力低的产膜酵母（俗称膜醭酵母）在葡萄汁或低酒精度的葡萄酒中，于有氧的条件下很容易生长繁殖，常常在...     

基于电子鼻和GC-MS技术对不同地区腌制大头菜挥发性物质的评价

该研究采用电子鼻和GC-MS结合的技术对云南玫瑰大头菜、襄阳大头菜和四川宜宾大头菜的挥发性物质进行了评价。电子鼻检测结果显示,襄阳大头菜和云南玫瑰大头菜在风味上比较相似,与四川宜宾大头菜相差较远。3种大头菜经GC-MS共检测出82种挥发性物质,酮类5种,醇类12种,硫醚类4种,醛类7种,酯类10种,烯烃类24种,烷类8种,酸类3种,其他9种。统计显示:襄阳大头菜和云南玫瑰大头菜的挥发性物质相似度较高,与四川宜宾大头菜主要的挥发性物质区别较大,与电子鼻结果相一致。电子鼻和GC-MS检测的差异可能与3种大头菜的制作工艺相关。     

基于电子鼻和GC-MS技术分析大头菜的挥发性风味物质

采用电子鼻和GC-MS技术,对四川成都、湖北襄阳和山东菏泽产腌制大头菜样品的风味品质进行了评价。电子鼻传感器T30/1,P10/2,T70/2,PA/2,P30/1,P30/2,TA/2对襄阳大头菜的响应值显著偏低(P0.05),而传感器LY2/gCT呈现出相反的趋势(P0.05)。通过主坐标分析、典范对应分析、多元方差分析和聚类分析发现不同地区产腌制大头菜整体风味品质存在显著差异(P0.05)。襄阳大头菜样品中主要挥发性风味物质为3-丁炔-1-醇、壬醛、乙酸异戊酯、D-柠檬烯、丙酮、乙酸乙酯和异戊醛,其平均相对含量分别为17.52%,13.44%,7.52%,7.19%,7.16%,6.83%,6.11%。     

基于低场核磁共振技术襄阳大头菜水分含量的测定

利用低场核磁共振技术采集襄阳大头菜不同部位的~1H信号,通过建立硫酸铜质量与~1H峰面积的线性关系方程,对大头菜中结合水、不易流动水与自由水的含量进行了定量,同时与直接干燥法测定的体相水(不易流动水和自由水之和)含量进行对比分析。通过相对定量分析发现,自由水为襄阳大头菜中水的主要分布形式,其平均相对含量达到了3种类型水总量的93.8%。襄阳大头菜样品中自由水、不易流动水和结合水的含量分别占到大头菜的61.56%~69.38%、0.53%~4.26%和0.09%~1.62%。低场核磁共振技术对襄阳大头菜体相水水分含量的测定结果极显著高于直接干燥法(P0.001)。由此可见,将低场核磁共振技术应用于襄阳大头菜水分含量测定中具有较大的可行性。     

基于电子舌、电子鼻和GC-MS分析襄阳大头菜新、老卤水滋味和挥发性物质

通过电子舌、电子鼻、气相色谱-质谱联用（GC-MS）技术对襄阳大头菜新、老卤水中的理化性质、滋味品质和挥发性物质进行分析。电子舌数据分析结果显示,襄阳大头菜新卤水的酸味、丰度和咸味均显著低于老卤水（P＜0.05）。电子鼻的数据分析结果显示,与新卤水相比,老卤水刺激性气味减少,芳香性气味更浓郁。GC-MS分析结果显示,新卤水中最主要的挥发性物质为异硫氰酸烯丙酯。对电子舌、电子鼻和GC-MS数据的主成分分析（PCA）结果显示,大头菜新卤水中W1S（甲烷）、W2S（乙醇）、W3S（烷烃）、W1W（有机硫化物、萜类）、W2W（有机硫化物）、W6S（氢气）和酯类含量较高,反映出了襄阳大头菜新卤水中异硫氰酸烯丙酯含量高;而大头菜老卤水中WIC（芳香类物质）、W3C（氨气、芳香类物质）、W5C（烷烃,芳香类物质）、醛类、酸味、丰度、后味A占据优势,说明襄阳大头菜老卤水中硫醚类物质含量丰富,醛类物质较多,酸味、丰度和后味A突出。     

Molecular monitoring of spoilage yeasts during the production of candied fruit nougats to determine food contamination sources

In the present work, we have analysed the yeast microbiota present in a manufacturing plant of candied fruits and nougats. Four yeasts species (Zygosaccharomyces bailii, Zygosaccharomyces rouxii, Sporobolomyces roseus, and Debaryomyces hansenii) and a filamentous fungi (Nectria mauriiticola) were identified according to restriction analysis of 5.8S-ITS rDNA. These identifications were subsequently confirmed by sequencing the D1/D2 domain of the 26S rRNA gene. Z. rouxii and Z. bailii were isolated at high frequency along the whole manufacturing process. Since food alteration by Z. bailii and Z. rouxii is the cause of important economic losses for the food industry, there is a need for differentiating yeasts at the strain level as an essential part of quality control programs in this industry. For this purpose, we have tested the performance of three molecular techniques (RFLP mtDNA, RAPD-PCR, and microsatellite with (GAC)5 and (GTG)5 primers) to differentiate strains belonging to these two Zygosaccharomyces species. Those techniques with the best discriminatory power were applied to differentiate Zygosaccharomyces species isolates. The results of this analysis indicate that one strain of Z. bailii and two strains of Z. rouxii were involved in the spoilage of candied fruits. Moreover, the Z. bailii strain was also present in the spoiled nougat, hence being responsible of this alteration.     

Pentadiene production from potassium sorbate by osmotolerant yeasts

Some yeast strains belonging to the species Zygosaccharomyces rouxii and Debaryomyces hansenii are capable of spoiling sorbate containing high-sugar foods by producing pentadiene, a volatile compound reported to have 'petroleum-like' odour. Quantification of the diminution of sorbate and the subsequent increase of pentadiene was performed by growing the yeasts in experimental media containing 600 g/l sucrose and different sorbate concentrations. Final sorbate concentrations were notably lower than their corresponding initial ones, and it was found that the higher the initial concentration of sorbate in the media, the higher the amount of pentadiene produced. In all cases, Z. rouxii was able to produce more pentadiene than D. hansenii when expressing pentadiene concentration as a function of cell biomass. These results suggest that pentadiene is a metabolite of sorbate.     

树莓酵素中耐高渗酵母菌的分离鉴定及生长特性研究

从树莓酵素中分离酵母菌,通过形态学特征、生理生化指标及26S r DNA序列分析进行鉴定,并对其生长特性进行研究,以期为植物酵素食品生产提供酵母菌资源。鉴定结果表明:分离出的Y1、Y2、Y3三株菌形态学特征相似,且均可在高糖环境下生长,26S r DNA序列与鲁氏接合酵母的同源相似性均高于99%,确定Y1、Y2、Y3均为鲁氏接合酵母(Zygosaccharomyces rouxii,Z.rouxii);生长特性研究结果表明:当培养基初始葡萄糖含量为300、450、600、750 g/L时,该菌种均可生长,延滞期分别为12、12、36、60 h,葡萄糖初始含量为900 g/L,生长缓慢;当培养基初始pH为1.5和2.0时,菌种的生长受到抑制,当pH为2.5、3.0、3.5时,菌种可以生长,延滞期分别为96、48、48 h。鲁氏接合酵母为树莓酵素中的优势酵母,具有耐高糖、耐低pH等耐高渗特性。      

甘油与鲁氏酵母共固定在高盐稀态酱油酿造中的应用

本文旨在研究相容性溶质之一的甘油对高渗透压环境下鲁氏结合酵母的保护作用,以及将甘油与鲁氏结合酵母共固定对高盐稀态酱油发酵的影响。添加不同浓度甘油至含3 mol/L氯化钠的YPD培养基中,观察酵母菌生长情况。同时,共固定甘油与鲁氏结合酵母,应用于高盐稀态酱醪发酵。结果显示,1.37 mmol/L甘油即可有效缓解高盐环境对鲁氏结合酵母的生长抑制作用,生长延滞期缩短达4~6 h。高盐稀态酱油发酵中试结果显示,与空白对照组相比,试验组蛋白质转化率提高幅度达2.23~5.64%,头油中各理化指标平均提前15 d达到空白组相同水平。综上所述,甘油作为一种相容性溶质可有效保护高盐环境下鲁氏结合酵母的生长繁殖,及其在高盐稀态酱醪发酵中的代谢性能,甘油与鲁氏接合酵母共固定技术能够提高酱油发酵的原料利用率、缩短发酵周期,在酱油酿造领域具有一定的实际应用价值。     

Fermentation and microflora of plaa-som, a thai fermented fish product prepared with different salt concentrations

Plaa-som is a Thai fermented fish product prepared from snakehead fish, salt, palm syrup and sometimes roasted rice. We studied the effects of different salt concentrations on decrease in pH and on microflora composition during fermentation. Two low-salt batches were prepared, containing 6% and 7% salt (w/w) as well as two high-salt batches, containing 9% and 11% salt. pH decreased rapidly from 6 to 4.5 in low-salt batches, whereas in high-salt batches, a slow or no decrease in pH was found. Lactic acid bacteria (LAB) and yeasts were isolated as the dominant microorganisms during fermentation. LAB counts increased to 10(8)-10(9) cfu g(-1) and yeast counts to 10(7)-5 x 10(7) cfu g(-1) in all batches, except in the 11% salt batch, where counts were 1-2 log lower. Phenotypic tests, ITS-PCR, carbohydrate fermentations and 16S rRNA gene sequencing identified LAB isolates as Pediococcus pentosaceus, Lactobacillus alimentarius/farciminis, Weisella confusa, L. plantarum and Lactococcus garviae. The latter species was only isolated from high-salt batches. Phenotypic characteristics, ITS-PCR and carbohydrate assimilation identified 95% of the yeasts as Zygosaccharomyces rouxii. It is concluded that the fermentation of plaa-som is delayed by a salt-level of 9% due to an inhibition of LAB growth. The growth of Z. rouxii has no influence on the fermentation rate, but may contribute positively to the flavour development of the product.     

Development of internal transcribed spacer regions amplification restriction fragment length polymorphism method and its application in monitoring the population of Zygosaccharomyces rouxii M2 in miso fermentation

Recently, the use of the dry yeast of Zygosaccharomyces rouxii M2 for miso (soybean paste) fermentation has been established. A molecular monitoring method was developed and validated in this study to analyze the population of Z. rouxii M2 during the fermentation. The method was based on the restriction patterns of internal transcribed spacer (ITS) regions of the rDNA using HaeIII and HhaI. Among the homologous ITS regions of Z. rouxii strains, Z. rouxii M2 produced diagnostic bands by which it can be differentiated from the other strains used. The specific restriction bands were due to the difference in nucleotide sequence of two different copies of ITS of Z. rouxii M2. Both ITS copies showed 94% sequence similarity but a 13-bp nucleotide substitution and a 19-bp deletion were found in the ITS1 region. Phylogenetic trees were constructed based on ITS and 18S rDNA sequences and it was found that the ITS sequences provide better resolution for the classification of Z. rouxii M2. Since Z. rouxii M2 is a promising strain for use in miso fermentation as a dry starter, the method developed is significant in terms of industrial application in monitoring the growth of Z. rouxii M2 in miso fermentation.     

基于响应面法的鲁氏酵母发酵培养基优化

鲁氏酵母（Zygosaccharomyces rouxii ）是酱油及酱类生产中风味形成的重要微生物之一。为了获得大量菌体,采用响应面法（RSM）对鲁氏酵母CCTCC M 2013310培养基进行了优化,Plackett-Burman（PB）设计对培养基中相关影响因素的效应进行评价,结果表明,葡萄糖、玉米浆和磷酸二氢钾对生物量影响显著。由中心组合及响应面分析优化确定优化培养基为葡萄糖12.03%,玉米浆2.24%,酵母粉1%,磷酸二氢钾0.26%,甘油3%,VB1 0.001%。优化培养基的生物量为28.28 g/L,比未优化前提高了4.5倍。