高盐稀态酱油发酵S3—2酵母基础发酵性能的研究

鲁氏酵母（S酵母）的耐盐能力抑制了其对高盐稀态酱油风味的改善作用。S3-2酵母是本试验室以S酵母为出发菌株,利用基因组重组技术构建的一株具有高耐盐度的酵母菌株。在YPD发酵培养基中对S3-2酵母进行基础发酵性能研究的结果表明,S3-2比S酵母具有更高的耐盐能力,S酵母能生长的最大盐度为19％,而S3-2酵母在含盐量高达21％的培养基中仍能够良好生长。在含盐量为18％的YPD发酵培养基中,S3-2酵母在提高醇类物质的种类和含量,对提高高盐稀态酱油风味具有重要的意义。     

Improvement of soy-sauce flavour by genome shuffling in Candida versatilis to improve salt stress resistance

Genome shuffling of Candida versatilis was applied to improve the soy-sauce flavour by further increasing salt stress resistance. A mutant S3-5, with a stronger resistance to salt, was isolated after three rounds of genome shuffling. It is found that S3-5 improved stress tolerance to higher potassium chloride and lithium chloride. S3-5 not only grew well in the YPD (peptone, yeast extract and dextrose) medium containing high concentrations of sodium chloride with various pH values, but also exhibited improvement of growth ability in soy-sauce medium. The main aroma compounds in soy sauce were distinctly improved. Notably, S3-5 produced about 2.78 times as much ethanol as the control strain. Another important aroma compound, 4-hydroxy-2 (or 5)-ethyl-5 (or 2)-methyl-3 (2H)-furanone (HEMF) was enhanced by up to 80%. Meanwhile, S3-5 accelerated flavour formation of soy sauce thus decreasing the total time required for the aroma development.     

Genome shuffling to improve fermentation properties of acetic acid bacterium by the improvement of ethanol tolerance

Whole‐cell biocatalysts are commonly limited by low tolerance of extreme process conditions such as alcoholic strength, temperature, pH and concentration of solute. Here, we describe the use of genome shuffling to improve the ethanol tolerance of acetic acid bacterium, which is a poorly characterised industrial strain. The best strain A3‐11 was constructed and selected after three rounds of shuffling from the wild‐type strain of acetic acid bacterium. A3‐11 could grow in liquid medium with 13% ethanol. During the vinegar fermentation, the organic acid components produced were distinctly improved by A3‐11. It was found that the content of acetic acid was twice as much as the control. Furthermore, the concentration of tartaric acid was 4.04‐fold more than the control. Notably, A3‐11 increased in butanedioic acid production by up to 71.73% compared with the control.     

Construction of a Magnesium-Enriched Yeast Strain and Study on Distribution of Magnesium in the Cells

The fusant strains ZBF-23, ZBF-65, and ZBF-90 with both higher biomass and higher magnesium content in cells were constructed by protoplast fusion. These three fusant strains were used as the source of genome shuffling from which a magnesium-enriched yeast strain F3-3 with better ability to enrich magnesium was obtained. The enriched magnesium of the shuffled strain F3-3 was about 1.83 and 1.57 times of that of the primary strains ZB-29 and ZB-104, respectively. Under optimal fermentation condition, the biomass and magnesium content of cells reached 16.16 g L^?1 and 14.26 mg g^?1. In the total enriched magnesium which was incorporated into the yeast cells, the organic magnesium was about 95.7%, which was mainly in vacuoles and mitochondria. Nucleic acid and protein in the cells also combined 2.59 and 2.91 mg Mg²⁺ g^?1, respectively. The magnesium-enriched yeast strain which possesses higher ability to accumulate and convert inorganic magnesium salts could be used as a magnesium-fortified food supplement.     

不同脱腥方法对鸡肝风味物质的影响

为研究不同脱腥方法鸡肝中风味物质的变化,采用感官评定、电子鼻与顶空固相微萃取-气质联用（headspace-solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS）技术,分析了不同脱腥方法的生熟鸡肝样品的挥发性风味物质。结果表明:姜酒浸泡、β-环状糊精包埋和酵母发酵均能显著降低生样品腥味值（P<0.05）;电子鼻响应值雷达图显示,组成鸡肝整体气味主要是硫化物、芳香成分和醇、醛酮类物质,姜酒浸泡能改变鸡肝原本的气味轮廓,且采用主成分分析（PCA）能较好区分各样品;HS-SPME-GC-MS共检出了124种挥发性风味物质,经姜酒浸泡和酵母发酵后,鸡肝中醛类物质含量均明显降低,多种致腥物质含量均明显下降。鸡肝熟化后,苯甲醛构成了鸡肝的主体风味,姜酒浸泡组中的乙醇含量明显高于对照组和酵母发酵组,是鸡肝熟化后保持较好风味的因素。研究表明,姜酒浸泡和酵母发酵能较好地改善鸡肝风味。     

Genome shuffling of Zygosaccharomyces rouxii to accelerate and enhance the flavour formation of soy sauce

BACKGROUND: The purpose of this study was to achieve rapid improvement of the flavour of soy sauce by increasing the salt stress resistance of Zygosaccharomyces rouxii. Here, we describe genome shuffling to improve the salt tolerance of Z. rouxii while simultaneously enhancing and accelerating flavour formation of soy sauce. RESULTS: A mutant, S3‐2, with a stronger resistance to salt, was selected after three rounds of genome shuffling. S3‐2 not only grew well in peptone/yeast extract/dextrose medium containing a high salt content with wide range of pH, but also exhibited stronger stress resistance to potassium chloride and lithium chloride. In high‐salt liquid fermentation, S3‐2 obviously accelerated flavour formation of soy sauce, thus decreasing the total time required for development of the aroma. In addition, S3‐2 gave high amino acid nitrogen and good flavour. In particular, the ethyl acetate content was 2.38 times that in the control. S3‐2 distinctly improved the formation of 4‐hydroxy‐2 (or 5) ‐ethyl‐5 (or 2) ‐methyl‐3 (2H) ‐furanone by up to 75%. Another important flavour component, 4‐ethylguaiacol, was also detected. CONCLUSIONS: Genome shuffling was successfully used to achieve significant improvements in flavour formation. The selected strain improved the main flavour components and amino acid nitrogen, thereby enhancing the quality of soy sauce. Copyright © 2009 Society of Chemical Industry     

固定化酵母在清香型白酒发酵的应用研究

采用固定化酵母发酵技术对传统白酒生产工艺进行部分改造，对其发酵工艺的研究结果显示，利用固定化酵母的效果均比对照组的产量和出酒率高3％，且不影响原酒的风味和其他理化指标。     

传统自然发酵黏豆包关键酵母的筛选鉴定

目的 筛选适宜谷物黏豆包发酵的酵母菌菌株。方法 以采集自黑龙江省不同地区的传统自然发酵黏豆包谷物发酵液为研究对象,通过高通量测序技术,分析发酵液中微生物多样性,再利用传统培养法对发酵液中的酵母菌进行分离,筛选出耐低温、耐低pH、起酵时间快和酵香风味好的酵母菌株。结果 通过高通量测序结果显示,在真菌菌属水平上, 3个地区样品共包含5个门、30个属、30个种,微生物群落为酿酒酵母属(Saccharomyces)、威克汉姆酵母属(Wickerhamomyces)、毕赤酵母属(Pichia)等,其中酿酒酵母属为首要优势菌属,次级优势菌皆为威克汉姆酵母属。在此基础上,利用平板划线分离出21株酵母菌,通过分子生物学鉴定, TY5、TY9和AC6为酿酒酵母, TY8和SC4为威克汉姆酵母, AC3为热带假丝酵母, SC3为季也蒙毕赤酵母,SC5为胶红酵母;TY5、TY8、TY9、AC6、SC6在pH为3、15℃条件下具有较好的生长性能,其中菌株TY9和AC6具有较强的耐酸性及耐低温性,且起酵时间快,菌株TY9发酵风味最好,呈现较强的谷物发酵风味。结论 筛选出一株耐低温、耐低pH、起酵时间快和酵香风味...     

微生物发酵法改良大豆肽风味的研究

该文研究了乳酸菌和酵母菌二次发酵法改良大豆肽的风味。实验结果表明,乳酸菌在发酵过程中,大豆肽溶液pH下降,总酸度上升,产生大量有机酸物质,乳酸菌发酵8h,大豆肽的风味最佳。酵母菌发酵过程中,大豆肽溶液中乙醇含量逐渐增加,产生大量醇类物质,酵母菌发酵2h,大豆肽溶液的风味最佳。经过乳酸菌和酵母菌发酵后,大豆肽的苦味和腥味消失,口感变成具有酸爽的杀口感,气味具有酒香味。因此,经过乳酸菌和酵母菌二次发酵工艺后,大豆肽的风味得到明显改善。     

几种酒类酿造酵母产酒精以外的糖消耗的研究

以葡萄酒1#酵母、葡萄酒6#生产酵母和啤酒酵母为研究对象,采用3,5-二硝基水杨酸光度法和比重瓶法分别测还原糖和酒精,对酒精以外的糖消耗进行研究.结果表明,酒类生产酵母在酒精发酵进入减速阶段初时达到峰值,对于控制压榨酒的风味具有指导意义.     

Fermentative capacity of Kluyveromyces marxianus and Saccharomyces cerevisiae after oxidative stress

Volatile compound production during alcoholic fermentation has been studied in the production of many beverages. Temperature, yeast strain, nutrients and pH have been identified as important factors in the production of volatile compounds. In addition, other factors could influence this production during the fermentation process as well. Oxidative stress could occur during yeast biomass production because oxygen is an essential nutrient that is added to the growth medium. The fermentation parameters and the volatile compound production of one Saccharomyces cerevisiae strain (MC4) and two Kluyveromyces marxianus strains (OFF1 and SLP1) were evaluated in relation to fermentation parameters after oxidative stress induced by hydrogen peroxide or menadione. These yeasts were compared with S. cerevisiae W303–1A and showed significant differences in ethanol production, ethanol yield and maximum ethanol production rate. K. marxianus (OFF1) showed better fermentative capacity after oxidative stress. The higher alcohol production decreased after oxidative stress by >35% after 72 h fermentation time, and the amyl alcohol decreased at a higher level (>60%); however, the isobutanol production increased after oxidative stress between 1.5 and 4 times. The yeasts produced significant concentrations of esters however ethyl lactate, ethyl caprylate and the ethyl caproate were not detected in the control fermentation, while in the stress fermentation they accounted for up to 3 mg/L. These results demonstrate that oxidative stress can play an important role in the final aroma profile; but it is necessary to guarantee adequate yeast growth to obtain the volatile compounds desired. Copyright © 2017 The Institute of Brewing & Distilling     

高浓麦汁中添加红枣汁对酵母发酵性能及啤酒风味的影响

该实验研究了红枣汁不同添加量（10%、15%、20%、25%、30%、35%）对啤酒高浓酿造中酵母发酵性能及风味物质的影响。结果表明,红枣汁的添加能显著提高酵母的发酵性能,发酵过程中红枣汁添加组总CO2质量损失均高于对照组,发酵结束后乙醇产量显著增加（P＜0.05）,其中,30%红枣汁添加量促发酵效果最好,发酵度为88.18%,酒精度为11.30%vol,与对照组相比,分别提高了4.16%和4.63%。添加红枣汁可显著影响啤酒的色值：红枣汁添加比例越高,啤酒L*值越低,a*值与b*值越高,总色差（ΔE值）与对照组差异越大。与对照组相比,红枣汁的添加减少了高级醇的形成,显著降低了啤酒的醇酯比。     

核桃奶酒的工艺优化

以鲜牛乳和核桃为原料,核桃经粉碎、磨浆、脱脂、调配等工序后以体积分数10%加入鲜牛乳中,并接酵母菌和乳酸菌进行混菌发酵得到核桃奶酒。通过单因素试验和正交试验设计优化发酵工艺。结果表明,发酵初始pH和发酵时间是影响核桃奶酒品质的显著因子,而发酵温度,不同酵母菌与乳酸菌的比例对核桃奶酒品质影响较小。当酵母菌与乳酸菌菌种比例为3%∶1%,发酵温度为30 ℃,发酵初始pH为4.5,发酵时间为8 d,可得到香味突出、口味独特的核桃奶酒。     

利用低温蒸煮工艺进行高浓度酒精发酵

本研究利用低温蒸煮工艺,探讨了玉米淀粉的高浓度酒精发酵。在80℃下对玉米粉进行蒸煮15min,同时加α—淀粉酶进行液化。经冷却后,在55℃下加糖化酶糖化30min。再度冷却到30℃,加酵母菌悬液发酵70h。并利用这一技术研究了产高浓度酒精酵母菌株的最佳发酵条件。在加糖化酶量200～300u/g原料。酵母接种量为3％(v/v),发酵温度为30℃,pH4～4.5,发酵周期为70h,原料水比为1:2条件下,所选用的菌株之一W_4可以产生17.5％(v/v)乙醇。发现该菌株在发酵速度和耐酒精能力方面明显地优于国内酒精厂常用的酵母菌株1300。在发酵结束时,成熟发酵醪的pH值为4.2。外观糖度为0(Bx),残还原糖为0.19％,残总糖为3.6％,淀粉利用率为90％。     

贻贝（Mytilus edulis）酶解液酵母发酵法脱腥工艺探究及其风味变化分析

为了消除贝类酶解物的腥味和苦味,本文以贻贝酶解液为研究对象,使用安琪果酒酵母进行发酵并以感官评分和蛋白损失率为指标对酵母添加量、发酵温度和发酵时间进行研究,确定发酵参数。利用感官科学结合氨基酸自动分析技术、质谱分析技术探究了发酵前后风味轮廓的差异。结果表明,当果酒酵母添加量为0.2%,在35℃下发酵2.0 h处理后,贻贝酶解液的鱼腥味、泥土味、哈喇味显著下降,发酵味和果香显著提升（P<0.05）。甜味氨基酸含量由1.33 mg/g显著上升至1.99 mg/g(P<0.05),鲜味氨基酸含量由1.60 mg/g提高到1.93 mg/g,苦味氨基酸含量由3.64 mg/g下降至3.34 mg/g。贻贝酶解液中共检测出挥发性风味物质32种,发酵后增加到40种,主要包括醛类、醇类、酯类、酸类、酮类和呋喃类化合物,其中辛醛、2,4-庚二烯醛、2-辛烯醛、壬醛、1-辛烯-3-醇为贻贝酶解液主要的异味来源。发酵后壬醛、2,4-庚二烯醛、2-辛烯醛不再作为酶解液的风味活性成分,产生鱼腥味的1-辛烯-3-醇和辛醛的OAV值也在发酵后大幅下降;此外,发酵后新增了癸醛、苯乙醛、2-壬酮、2-十一...     

Disruption of ubiquitin-related genes in laboratory yeast strains enhances ethanol production during sake brewing

Sake yeast can produce high levels of ethanol in concentrated rice mash. While both sake and laboratory yeast strains belong to the species Saccharomyces cerevisiae, the laboratory strains produce much less ethanol. This disparity in fermentation activity may be due to the strains' different responses to environmental stresses, including ethanol accumulation. To obtain more insight into the stress response of yeast cells under sake brewing conditions, we carried out small-scale sake brewing tests using laboratory yeast strains disrupted in specific stress-related genes. Surprisingly, yeast strains with disrupted ubiquitin-related genes produced more ethanol than the parental strain during sake brewing. The elevated fermentation ability conferred by disruption of the ubiquitin-coding gene UBI4 was confined to laboratory strains, and the ubi4 disruptant of a sake yeast strain did not demonstrate a comparable increase in ethanol production. These findings suggest different roles for ubiquitin in sake and laboratory yeast strains.     

Reduced acetaldehyde production by genome shuffling of an industrial brewing yeast strain

High levels of acetaldehyde produced by yeast during fermentation can be of concern to product quality. A novel approach, based on genome shuffling, was applied to reduce the production of acetaldehyde by industrial brewing strain YS86. Four isolates with different impacts of acetaldehyde concentration were obtained from populations generated by ultraviolet irradiation and nitrosoguanidine mutagenesis. These yeast strains were then subjected to recursive pool‐wise protoplast fusion. A strain library that was likely to yield positive colonies was created by fusing the lethal protoplasts obtained from both UV irradiation and heat treatments. After two rounds of genome shuffling, a recombinant YSF2–9 strain produced less acetaldehyde than wild‐type strain YS86, by 64.5 and 66.2% in laboratory and pilot plant fermentations, respectively. The shuffled yeast strain YSF2–9 was genetically stable and may have a potential application in brewing industry for managing acetaldehyde in beer. Copyright © 2017 The Institute of Brewing & Distilling     

优良苹果蒸馏酒酵母菌株的筛选

以苹果浆发酵的苹果蒸馏酒为研究对象,采用实验室保藏及购买的10株酵母(W1、W2、W3、H1、H2、H3、7#、LY、G1、G2)为备选菌株,通过系统的对比试验和结果评价,筛选出一株最佳的苹果蒸馏酒生产用酵母菌7#,其发酵的原酒酒精度可达13.8%vol,蒸馏后具有典型的苹果蒸馏酒风味。     

Effects of Fermentation Parameters and Cell Wall Properties on Yeast Flocculation1

Industrial wort was fermented with a NewFlo phenotype ale yeast in lab‐scale cylindrical fermenters. The effects of various fermentation parameters and yeast cell wall properties on yeast flocculation were studied during 120 h fermentation. The evaluation of the cell volume during the fermentation revealed a non‐normal distribution (p < 0.05) at most fermentation times. Overall yeast cell size initially decreased during the first 24 h of fermentation then increased during the 24–60 h fermentation period. Cell size subsequently declined until the end of fermentation presumably due to floc settling. While yeast flocculation began after 24 h fermentation, most flocs remained in suspension until 60 h when the average turbulent shear rate caused by CO₂ evolution declined to below 8 s^?1. Both the Helm's flocculence and cell surface hydrophobicity values rapidly increased to high numbers from 24 h onward. Changes in the orthokinetic capture coefficient (α₀) value with fermentation time, measured in fermenting worts, indicated a significant increase (p < 0.001) after 24 h of fermentation. Presumably, this change was due to increases in ethanol and the decline in sugar concentration with time. Although a significant positive correlation (p < 0.05) was observed between zymolectin densities and cell surface areas, the total zymolectin level on yeast cell walls did not change significantly with fermentation time (p > 0.05). Interestingly, no significant difference existed in Helm's flocculation values of suspended and settled yeast cells (p > 0.05). The flocculation rate of LCC125 was readily inhibited by addition of glucose or maltose. Results suggest that fermentable sugar levels and shear force exert major influences on yeast flocculation during beer fermentations.     

融合魏斯氏菌和异常威克汉姆酵母混菌发酵荞麦酸面团馒头的香气物质特征

应用分离自我国酒鬼酒曲中的融合魏斯氏菌和梅兰春酒醅中的异常威克汉姆酵母进行混菌发酵,通过测定菌株生长曲线探索两株菌的共生作用,采用固相微萃取结合气质联用(SPME-GC-MS)和气相电子鼻技术,对比混菌发酵酸面团(MBF)和单菌发酵酸面团及其荞麦馒头风味化合物的差异性。结果表明,在MBF中乳酸菌、酵母菌菌落数分别达到9.38 log CFU/g、8.51 log CFU/g,两株菌具有良好的共生关系。发酵后荞麦酸面团的主要特征风味物质为乙醇、乙酸、乙酸乙酯、乙偶姻和异戊醇。与酵母菌单菌发酵荞麦酸面团馒头相比,混菌发酵馒头中酯类物质相对含量从5.27%提高到9.53%,结合ROAV分析,混菌发酵荞麦馒头的风味强度明显高于单一乳酸发酵和单一酵母发酵,赋予馒头更浓郁的酒香和果香,感官评定证实其整体可接受度高于其他组。