温度和翻醅对食醋固态发酵产酸的影响

采用原位分析及模拟发酵的方法研究了温度和翻醅对食醋固态发酵的影响。结果表明,乙酸和乳酸是山西老陈醋中主要的有机酸,对两者影响最大的发酵条件是温度和溶氧,其中乳酸在发酵中前期（1～5 d）具有较高的生成速率,乙酸则于发酵中后期（5～9 d）快速积累。主要的醋酸菌巴氏醋杆菌（Acetobacter pasteurianus）及主要的乳酸菌瑞士乳杆菌（Lactobacillus helveticus）分别在30 ℃、40 ℃具有最高的生长和乙酸、乳酸代谢活性。翻醅有利于醋酸菌的生长和乙酸生成相关基因的表达,但对乳酸菌的生长和乳酸脱氢酶的表达则有负面影响。     

保宁醋醋曲中产多糖乳酸菌的筛选及其代谢产物分析

保宁醋因其复杂微生物体系和酿造工艺而形成独特风味,其风味物质和营养成分主要由各种功能性微生物发酵生成,其中乳酸菌是非常关键的一类菌株,其对保宁醋的风味和营养物质的形成具有重要作用。本研究以稀释涂布平板法从保宁醋醋曲中分离得到12株乳酸菌,通过定性试验、产酸率、耐酸试验和胞外多糖测定等实验,得到一株产多糖量为191.98 mg/L、产酸率为1.62%的乳酸菌L7,鉴定为发酵乳酸杆菌(Lactobacillus femertum),其发酵液中3-羟基-2-丁酮和乙酸相对含量较高,分别为36.22%、45.76%,HPLC检测到乳酸、乙酸,含量分别为66.56 mg/100 mL和104.08 mg/100 mL,这表明L7将有利于提高食醋酸度以及川芎嗪含量。产多糖乳酸菌在食醋发酵过程中的具有重要作用,而此次所得乳酸杆菌对保宁醋生产和发酵工艺改良具有指导意义。     

高乳酸食醋酿造技术研究进展

多年来,人们对食醋的认知一直停留于一种含有醋酸的酸味调味品阶段,忽略了食醋中不挥发酸对食醋风味的贡献。国内外食醋酿造技术研究进展显示,东西方食醋因原料、工艺差异,食醋中的有机酸成分存在很大差异,东方谷物醋较西方果醋风味丰富,尤其是食醋中的主要不挥发酸成分-乳酸对调节食醋风味协调性具有重要作用。因此,在食醋酿造过程中,可通过采用先进技术,对关键工艺环节进行特定乳酸菌种及代谢产物的靶向调控,调节食醋中醋酸与乳酸的合理配比。通过提升不挥发酸在总酸中所占的比例,增加具有醇厚味感的乳酸含量,减少醋酸对味觉的刺激,使食醋口感更加绵酸柔和,可全面提高食醋风味品质,为未来拓展更大的市场空间。     

共同定化多菌种发酵椪柑果醋工艺研究

以海藻酸钠为固定化材料,研究了多菌种（酿酒酵母、产香酵母、乳酸茵、醋酸菌）共固定化技术在椪柑果醋发酵中的应用。结果表明,固定化多菌种发酵椪柑果醋的最佳工艺条件为：酒精发酵阶段,接种量20％（v／v）、发酵温度32℃、时间60h、底物糖度23％;醋酸发酵阶段,接种量20％、发酵温度35℃、时间7d。所酿造的果醋具有椪柑的固有色泽、香气,无沉淀物,酸味柔和适中。     

固态发酵食醋生产过程中主要微生物及风味生成的探讨

实验研究了不同时间、不同醋醅层次的微生物分布和数量变化规律,探索影响风味形成的因素。结果表明,发酵前5 d,酵母菌和乳酸菌迅速增殖,第5天酵母菌数达到最高3.4×107 CFU/g,乳酸菌最高为3.2×107 CFU/g,以乳酸为主的不挥发酸同时也生成较快;醋酸菌前3 d增长迅速,之后缓慢增长并以生成挥发性的醋酸为主,第11天醋酸菌数量达到峰值为4.0×107 CFU/g,13 d以后逐渐消亡。醋酸发酵初期,pH值迅速下降,不挥发酸迅速增加,不挥发酸占总酸的比值最大在第7天,为87.22%;总酸在发酵中期的7～13 d增幅最大。乳酸菌的消长影响着不挥发酸的生成,醋酸菌的消长影响着总酸的生成,醋酸发酵过程中控制合适的发酵条件,使两者的相互协调生长,有利于产品口感风味的调和。     

孝感酒酿微生物多样性及优势菌特性研究

采用PCR-变性梯度凝胶电泳(PCR-DGGE)技术法检测不同酒酿样品中微生物多样性,发现酒酿中包含酿酒酵母属(Saccha-romyces sp.)、毕赤酵母属(Pichia sp.)、乳杆菌属(Lactobacillus sp.)和葡萄糖杆菌属(Gluconobacter sp.)等。从3种酒酿中分离3株优势酵母菌、1株乳酸杆菌和1株球菌,经鉴定为2株酿酒酵母(Saccharomyces cerevisiae)、1株贝酵母(Saccharomyces bayanus)、坚韧肠球菌(Enterococcus durans)和植物乳杆菌(Lactobacillus plantarum)。3株优势酵母菌MJN2、17JN2和MJN3表现了较强的产酒精能力,培养48h后,酒精产量分别达到1.4%vol、1.5%vol和2.2%vol,2株优势乳酸菌JN3和JN1表现出了较强的产酸能力,培养24h后,pH值分别达到5.13和3.69。     

浙江玫瑰醋发酵过程中细菌菌群结构变化与有机酸形成相关性分析

基于Illumina MiSeq高通量测序对浙江玫瑰醋“冲缸放水”后的醋样中细菌V4区进行测序,并用高效液相色谱对醋样有机酸含量进行测定,得出玫瑰醋发酵过程中细菌相对丰度以及有机酸含量的变化,并用双向正交偏最小二乘（bidirectional orthogonal partial least squares,O2PLS）法模型对两者相关性进行分析,结果表明：玫瑰醋在“冲缸放水”后的发酵过程中,醋酸杆菌属和乳酸杆菌属在细菌菌群中占绝对优势（相对丰度之和大于80%）;玫瑰醋中有机酸含量一直呈现上升趋势,乙酸和乳酸含量最高,对玫瑰醋有机酸含量进行系统聚类分析和主成分分析分析,可以将醋样分为发酵前期、发酵中期、发酵后期三大类,各类醋样有机酸组成差异显著;利用O2PLS模型对细菌与有机酸相关性分析,得到23 个与有机酸相关重要性指标（VIP（pred））大于1的细菌属,包括Acetobacter、Lactobacillus、Methylobacterium等;对VIP（pred）大于1的细菌与有机酸进行相关性分析,作出细菌与有机酸相关性系数Heatmap,并得出与各种有机酸相关性系数|ρ|＞0.6的高度相关细菌属。为找寻玫瑰醋发酵过程中的功能微生物,提升玫瑰醋品质提供数据支持。     

基于高通量测序解析四川晒醋固态发酵过程中细菌群落变化

本文以四川晒醋固态发酵过程的醋醅为研究对象,采用高通量测序分析其细菌群落结构及其丰度。结果表明,在整个发酵过程中,醋醅中的细菌群落共包括166个属。当发酵第15 d时,经可操作分类单元（operational taxonomic units, OTUs）分析共得到11个门、14个纲、36个目、45个科和79个属;通过UPGMA聚类分析初步探索了糖化、酒精发酵和醋酸发酵同池发酵的分界节点,即第1~3 d为发酵初期,其优势细菌为乳杆菌属（Lactobacillus）和魏斯氏菌（Weissella）;第5~11 d为发酵中期,其优势细菌为乳杆菌属（Lactobacillus）和醋杆菌属（Acetobacter）,在发酵第7 d时细菌的丰富度和多样性达到最高值;第13~17 d为发酵后期,其优势细菌为醋杆菌属（Acetobacter）、贪铜菌属（Cupriavidus）、嗜糖假单胞菌属（Pelomonas）和鞘氨醇单胞菌属（Sphingomonas）。本研究揭示了晒醋固态发酵过程中细菌群落演替,为进一步研究晒醋发酵过程中微生物群落结构奠定了基础。     

Microbial communities in the garbage composting with rice hull as an amendment revealed by culture-dependent and -independent approaches

The diversity and succession of microbial communities during the garbage composting with rice hull as an amendment were studied by denaturing gradient gel electrophoresis (DGGE) and clone library analysis of PCR-amplified 16S ribosomal DNA (rDNA) with universal primers. Based on temperature changes, the composting process could be divided into thermophilic, cooling-down, and maturing stages. The DGGE profiles and clone library analysis revealed that the microbial community drastically changed during the composting process from the thermophilic to the maturing stages. The dominant bacterial group changed from the phylum Firmicutes in the thermophilic stage to the phylum Bacteroidetes in the maturing stage. This change in microbial communities may be significant for the composting process. The diversity of cultivated bacteria isolated from samples taken at various stages of the composting process was low. A total of 87 isolates were classified as belonging to only four different groups. These groups were also detected in the DGGE profiles and by the clone library analysis. Our study indicated that a combination of culture-dependent and -independent approaches could be very useful for monitoring both bacterial diversity and the succession of communities during the composting process. This study would be beneficial for assessing the ecological consequences of disposal of organic waste.     

永川毛霉型豆豉在发酵过程中微生物总量与区系变化规律

采用巢式聚合酶链式反应配合变性梯度凝胶电泳技术对永川豆豉发酵过程中微生物区系生态演化进行解析。结果表明：永川豆豉在制曲过程中霉菌和细菌呈对数增长,进入后发酵阶段菌落总数快速下降,并保持在较低水平。永川豆豉在制曲前期有多种乳酸菌生长,后期乳酸菌受霉菌增长抑制,种类减少。在后发酵阶段奥德赛芽孢杆菌（Bacillus odysseyi）、乳酸杆菌（Lactobacillus oligofermentans）和乳酸杆菌（Lactobacillus lindneri）是优势菌群。同时在制曲初期也发现了费格森埃希菌（Escherichia fergusonii）等杂菌生长。永川豆豉制曲阶段优势霉菌是总状毛霉（Mucor racemosus）,同时伴有有性根霉（Rhizopus sexualis）、匍枝根霉（Rhizopus stolonifer）、大孢联轭霉（Syzygites megalocarpus）、米根霉（Rhizopus oryzae）的生长,后发酵阶段有接合酵母（Zygosaccharomyces sp.）的参与。     

四川不同地区的熟醋及其固态发酵过程中有机酸含量变化分析

为了解不同地区的四川麸醋中有机酸含量差异及其固态发酵过程中有机酸含量变化,采用高效液相色谱对其7种主要的有机酸含量进行测定。结果表明,在四川麸醋固态发酵过程中,乙酸由1.2712 mg/mL升高至3.1214 mg/mL,是含量最高的酸,占总有机酸58.12%。而含量次之的是乳酸,由0.8858 mg/mL升高至1.3216 mg/mL,占总有机酸32.67%,其中乙酸和乳酸变化最为显著,草酸、柠檬酸、酒石酸、柠檬酸和酒石酸变化不明显。对结果进行主成分分析发现,在熟醋中,乳酸对四川麸醋显示了较高的相关性,四川麸醋中乳酸的含量明显高于其它地区熟醋中乳酸的含量,这表明乳酸可以将四川麸醋与其它地域的食醋有效的区分开。在四川麸醋固态发酵过程中,发酵前期3d^10d与乳酸体现了较高的关联性,后期12 d^23 d与乙酸具有较高的相关性。     

The microbial ecology of cocoa bean fermentations in Indonesia

Cocoa beans are the principal raw material of chocolate manufacture. The beans are subject to a microbial fermentation as the first stage in chocolate production. The microbial ecology of bean fermentation (Forastero and Trinitario cultivars) was investigated at three commercial fermentaries in East Java, Indonesia by determining the populations of individual species at 12-h intervals throughout the process. The first 2-3 days of fermentation were characterised by the successional growth of various species of filamentous fungi, yeasts, lactic acid bacteria and acetic acid bacteria. The principal species found were Penicillium citrinum, an unidentified basidiomycete, Kloeckera apis, Saccharomyces cerevisiae, Candida tropicalis, Lactobacillus cellobiosus, Lactobacillus plantarum and Acetobacter pasteurianus. The later stages of fermentation were dominated by the presence of Bacillus species, mostly, Bacillus pumilus and Bacillus licheniformis. Glucose, fructose, sucrose and citric acid of the bean pulp were utilised during fermentation, with the production of ethanol, acetic acid and lactic acid that diffused into the beans. The filamentous fungi were notable for their production of polygalacturonase activity and probably contributed to the degradation of bean pulp.     

实时荧光定量PCR监测镇江香醋醋酸发酵过程中微生物变化

对镇江香醋醋酸发酵阶段醋醅中功能微生物的变化进行定量分析。建立了实时荧光定量PCR方法,对醋酸发酵阶段醋醅中总细菌、总真菌、醋酸菌、乳酸菌和酵母的动态变化进行了定量分析。研究结果表明,发酵起始阶段(1～7天)醋醅中总细菌、醋酸菌和乳酸菌的生物量快速上升,分别于第6、7、4天达到最大值,为4.85×1011,1.14×1010和3.37×1011copies/g干醅。随后各类细菌的生物量逐渐下降,并维持在一定水平。醋醅中总真菌和酵母的生物量在发酵前期变化不大,7天后至发酵结束总真菌的生物量逐渐下降为7.59×104copies/g干醅,而酵母生物量则在发酵8～12天内下降为0。     

半连续液态深层发酵红枣醋及其抗氧化活性

以红枣酒为原料,采用巴氏醋酸杆菌（Acetobacter pasteurianus）进行半连续液态深层发酵,研究不同接种量和溶氧量对醋酸发酵的影响,并对发酵过程中有机酸的变化和红枣醋的抗氧化活性进行分析。结果表明,采用半连续液态深层发酵酿制红枣醋,在溶氧量10%、分割留种量50%的条件下,发酵周期可缩短到14.5～15.5 h。红枣酒醋酸发酵初期奎宁酸和苹果酸含量均增加1倍以上,但在后续的快速产酸阶段又逐渐降低至发酵前的水平,乳酸在发酵初期被转化,最终降低至43.55 mg/100 mL。红枣酒经过醋酸菌发酵后,其中的总酚和总黄酮含量以及1,1-二苯基-2-苦肼基（DPPH）自由基清除能力、Fe3+还原能力、2,2'-联氮双（3-乙基苯并噻唑啉-6-磺酸）（ABTS）自由基清除能力分别提高16.59%、42.98%、24.66%、27.87%和38.07%,因此可作为增强红枣产品功能特性的加工手段。     

纳豆菌对液态糙米醋品质的影响

以糙米为主要原料,以阿魏酸和总酸含量为评价指标,采用单因素试验和正交试验优化液态发酵糙米醋醋酸发酵条件。结果表明,最佳工艺条件为纳豆菌接种量2.0%、初始乙酸含量1.0%、初始酒精度7.0%vol、发酵温度32 ℃。采用优化的液态发酵工艺酿造的糙米醋呈暗黄色、澄清、酸味柔和,总酸含量达7.26 g/100 mL、阿魏酸含量为6.57 mg/L。纳豆菌与醋酸菌混合发酵,提高了糙米醋整体品质,新增了功效成分阿魏酸,提升了糙米醋的功能性。     

微生物固态发酵茶叶食醋的工艺研究

以云南大叶种绿茶、玉米为主要原料,人工添加黑曲霉、酿酒酵母、醋酸菌等微生物,采用固态发酵技术,对发酵原料进行浸提、过滤、挑选、浸泡、蒸煮、糖化、酒精发酵、醋酸发酵等步骤,在相应阶段添加微生物菌种进行混菌发酵。结果表明:控制好各发酵环节的温度、添加物的比例等因素,对发酵料进行过滤、陈化、灭菌等处理,结果形成了兼有茶和醋独特风味的绿茶醋,具有很好的保健和营养功效。对成品茶醋进行感官指标、理化指标和卫生指标测定,符合国家质量标准。     

Dynamics of the microbial community responsible for traditional sour cassava starch fermentation studied by denaturing gradient gel electrophoresis and quantitative rRNA hybridization

The microbial community developing during the spontaneous fermentation of sour cassava starch was investigated by cultivation-independent methods. Denaturing gradient gel electrophoresis (DGGE) of partially amplified 16S rDNA followed by sequencing of the most intense bands showed that the dominant organisms were all lactic acid bacteria (LAB), mainly close relatives of Bifidobacterium minimum, Lactococcus lactis, Streptococcus sp., Enterococcus saccharolyticus and Lactobacillus plantarum., Close relatives of Lb. panis, Leuconostoc mesenteroides and Ln. citreum were also found. A complementary analysis using hybridization of 16S rRNA with phylogenetic probes was necessary to detect the presence of the recently discovered species Lb. manihotivorans. Although it represented up to 13% of the total lactic acid bacteria of sour cassava starch, this species could not be detected by DGGE as the PCR product migrated to the same position as Lc. lactis. In addition, it was shown that a strong pH decrease in the time course of fermentation was most probably responsible for the competitive selection of acid-resistant LAB vs. both homo and heterofermentative acid-sensitive LAB.     

Assessment of the microbial diversity of Brazilian kefir grains by PCR-DGGE and pyrosequencing analysis

The microbial diversity and community structure of three different kefir grains from different parts of Brazil were examined via the combination of two culture-independent methods: PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and pyrosequencing. PCR-DGGE showed Lactobacillus kefiranofaciens and Lactobacillus kefiri to be the major bacterial populations in all three grains. The yeast community was dominated by Saccharomyces cerevisiae. Pyrosequencing produced a total of 14,314 partial 16S rDNA sequence reads from the three grains. Sequence analysis grouped the reads into three phyla, of which Firmicutes was dominant. Members of the genus Lactobacillus were the most abundant operational taxonomic units (OTUs) in all samples, accounting for up to 96% of the sequences. OTUs belonging to other lactic and acetic acid bacteria genera, such as Lactococcus, Leuconostoc, Streptococcus and Acetobacter, were also identified at low levels. Two of the grains showed identical DGGE profiles and a similar number of OTUs, while the third sample showed the highest diversity by both techniques. Pyrosequencing allowed the identification of bacteria that were present in small numbers and rarely associated with the microbial community of this complex ecosystem.     

乙酰辅酶A羧化酶对乳酸片球菌耐酸性能的影响

通过对来源于山西老陈醋固态酿造过程中的乳酸菌分离株的耐醋酸性能分析,筛选得到了醋酸耐受性较优的乳酸片球菌（Pediococcus acidilactici）AAF3-3,该菌株对其他种类的酸压力（乳酸和盐酸）也表现出一定的耐受性。利用定量实时聚合酶链反应（qRT-PCR）对该菌株中乙酰辅酶A羧化酶基因（acc）的转录水平进行分析发现,其在醋酸、乳酸和盐酸下的转录水平分别是无压力条件下的4.32、2.02和1.13倍,均出现了明显上调。进一步构建该基因的过表达菌株并进行耐酸性能分析。结果表明,与对照菌株相比,acc过表达菌株在3种酸压力下的生长性能和存活性能均有所提高,其中,3%（V/V）醋酸条件下培养24 h时过表达菌株的相对活菌数是对照菌株的24倍。这表明乙酰辅酶A羧化酶在乳酸片球菌AAF3-3耐受不同种类的酸压力中发挥着重要作用。     

Evaluation and optimisation of bacterial genomic DNA extraction for no-culture techniques applied to vinegars

Direct genomic DNA extraction from vinegars was set up and suitability for PCR assays performed by PCR/DGGE and sequencing of 16S rRNA gene. The method was tested on 12 intermediary products of special vinegars, fruit vinegars and condiments produced from different raw materials and procedures. DNAs extraction was performed on pellets by chemical, enzymatic, resin mediated methods and their modifications. Suitable yield and DNA purity were obtained by modification of a method based on the use of PVP/CTAB to remove polyphenolic components and esopolysaccharides. By sequencing of bands from DGGE gel, Gluconacetobacter europaeus, Acetobacter malorum/cerevisiae and Acetobacter orleanensis were detected as main species in samples having more than 4% of acetic acid content. From samples having no acetic acid content, sequences retrieved from excised bands revealed high similarity with prokaryotes with no function on vinegar fermentation: Burkholderia spp., Cupriavidus spp., Lactococcus lactis and Leuconostoc mesenteroides. The method was suitable to be applied for no-culture study of vinegars containing polyphenols and esopolysaccharides allowing a more complete assessment of vinegar bacteria.