Screening of the Fine Brewer's Yeast Strain

优良啤酒酿造酵母菌株的选育摘要啤酒酿造酵母菌种的优劣对啤酒质量起着至关重要的作用，可以说酵母是啤酒的灵魂。因此选育性能优良的啤酒酿造酵母菌种是啤酒工业的一项重要任务。本研究以啤酒酵母菌株BW和H38为出发菌株，通过物理化学因子处理，筛选优良的啤酒酵母菌株，并为原生质体融合提供直接亲本；运用原生质体融合技术，构建和筛选优良的啤酒酵母菌株。菌株BW经亚硝酸（0.04mol/L处理10min，致死率82％）诱变，筛选得到一株发酵液中高级醇含量较低的菌株N1。该菌株在12℃下三角瓶发酵8d，发酵液中的双乙酰和高级醇含量分别为0.1000mg/L和87.68mg/L，比出发菌株BW的（0.1230mg/...Screening of the Fine Brewer’s Yeast StrainAbstract The brewer’s yeast strain is the base and key of the beer brewage production. To improve the beer quality and yield, in the first, an excellent yeast strain must be selected. In the study, strain Saccharomyces cerevisiae BW and H38 were used as the original strains. After treatment with physical and chemical mutagen and selection, the fine mu...学位：理学硕士院系专业：生命科学学院生物学系_微生物学学号：20022602

Screening of the Fine Brewer’s Yeast Strain UN_(41)

以啤酒酵母(Saccharomyces cerevisiae) W作为出发菌株,用亚硝酸和紫外线连续诱变,在含双乙酰 150μg/mL(亚硝酸诱变)或200μg/mL(紫外线诱变)的麦芽汁琼脂平板上分离抗双乙酰的菌株,通过三角瓶发酵筛选得到一株优良的啤酒酵母菌株UN41.该菌株在500 mL三角瓶装300 mL 12°Bx麦芽汁的培养基中,12℃下发酵8 d,发酵液的发酵度为65.0%;双乙酰、高级醇和乙醛的含量分别为0.076 8 mg/L、92.15 mg/L和9.33 mg/L,比出发菌株W的降低了37.6%、19.9%和27.6%.The objective of this work was to obtain a fine brewer’s yeast strain by mutating Saccharomyces cerevisiae W.After continual mutagenesis with nitrous acid (HNO_2) and ultraviolet rays (UV) and isolating the mono-colonies growing on 6°Bx wort plate agar containing diacetyl 150 μg/mL (as treated with HNO_2) or 200 μg/mL (as treated with UV),49 mutants was selected.Fermentation degree and diacetyl,aldehyde and total higher alcohols content were taken as the main target,the fine strain UN_(41) was obtained from strain Saccharomyces cerevisiae W.In the fermented liquid of strain UN_(41) under the fermentation conditions of 500 mL flask with 300 mL 12°Bx wort at 12℃ for 8 days,degree of fermentation was 65.0%,the content of diacetyl,higher alcohols and acetaldehyde were 0.076 8 mg/L,92.15 mg/L and 9.33 mg/L,37.6%,19.9% and 27.6% lower than that of the original strain W,respectively. The strain UN_(41) is of potentially applicable to beer brewing

Study on Optimization of Flocculence and Fermentation Characteristics of Brewer's Yeast by Protoplast Fusion

以发酵度较高、凝絮性较差的啤酒酵母菌株H38的原生质体为受体,以凝絮性较强、发酵度较低的啤酒酵母菌株N1热灭活的原生质体为供体进行融合.用正交试验法分别优化两亲株的原生质体制备和再生的条件以及原生质体融合的条件.用制霉菌素抗性为遗传标记选择融合子.融合子初筛时以凝絮性为指标,复筛时以发酵度和发酵液中的主要风味物质的含量为指标.对得到的融合子进行了异核体和遗传稳定性的检验,结果得到两株凝絮性以及发酵特性较好的菌株HN31和HN40.The objective of this work was to optimize the flocculence and fermentation characters of brewer's yeast by protoplast fusion technology.Saccharomyces cerevisiae H38 and N1 were used as the parent strains for protoplast fusion.The strain H38 was a non-flocculence strain with a relatively high fermentation degree and the strain N1 was a strain with a relatively low fermentation degree and the relatively strong flocculence.The formational and regenerative conditions of strain H38 and N1 protoplast were optimized with the orthogonal test method.The protoplast fusants were constructed with H38 protoplasts as receptors and heat-inactivated strain N1 protoplasts as donors.The fusion conditions between strain H38 and N1 protoplast were optimized with the orthogonal test method.Anti-mycostatin character were used as genetic mark to select the fusion strains.Fusants were selected with flocculation ability,fermentation degree and content of diacetyl,acetaldehyde,total higher alcohols in the fermented liquid as screening criteria.As a result,two fine fusants with the relatively strong floccutence,high fermentation degree and low content of dicetyl,acetaldehyde and total alcohole in the fermented liquid were obtained.福建雪津啤酒有限公司资

Studies on fermentative characters of a brewer,syeast protoplast fusant GR8

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。The fermentative characters of the brewer,s yeast protoplast fusant GR8 were studied. The results showed that flocculence ( Burns value )of the strain GR8 was 3.0mL. Under the fermentative conditions of 500mL flask with 300mL 12oBx wort at 12oC for 8 days,the real degree of fermentation of the strain GR8 was 66.5%, and content of diacetyl, acetaldehyde, acetic ether and total higher alcohols in the fermented liquid of the fusant GR8 were 0.0583mg/L, 9.66mg/L, 22.8mg/L and 91.20mg/L, respectively. The fermentative characters of the strain GR8 was stable during continued transfer of culture. The results showed that the strain GR8 has a good prospect in the application for beer brewing

Pilot Beer Brewing Test of Protoplast Fusant HN31-6 of Saccharomyces cerevisiae

为了考察啤酒酵母融合株HN31-6的啤酒酿造生产性能,以12.5°Bx麦芽汁为培养基,用500 L发酵罐在12℃下发酵,发酵期间每天取样测定发酵液的发酵度和酒精度以及发酵液的双乙酰、乙醛、高级醇和酯类等挥发性物质的含量.结果表明:在上述条件下,发酵14 d,发酵液的发酵度和酒精度分别为69.9%和4.46%;双乙酰和乙醛的含量分别为0.036 4 mg/L和4.53 mg/L;异戊醇、异丁醇和正丙醇的含量分别为46.47、8.34和9.82 mg/L,总高级醇的含量为64.6mg/L;甲酸乙酯、乙酸乙酯、乙酸异丁酯、乙酸异戊酯和己酸乙酯的含量分别为0.132、21.92、0.037、2.22和0.293 mg/L,总酯为24.6 mg/L;该菌株的发酵度以及发酵液的酒精、双乙酰、乙醛、总高级醇和一些酯类等的含量均达到国家优质啤酒的标准,啤酒口感良好.该融合株在啤酒酿造生产中具有很好的应用前景.In order to inspect the characters of beer brewing of protoplast fusant HN31-6 of Saccharomyces cerevisiae,the fermentation test was carried out under the conditions of 500 L fermentor with 400 L 12.5° Bx wort as the medium at 12℃ for 14 days.The fermentative degree of the fermented liquid and the contents of diacetyl etc volatility substances were analyzed during the fermentation.The results showed that the fermentative degree and alcohol degree of the fermented liquid of fusant HN31-6 under the above-mentioned conditions were 69.9% and 4.46%,respectively.The contents of diacetyl and acetaldehyde in the fermented liquid were(0.036 4) mg/L and 4.53 mg/L,respectively.The contents of isopentitol,isobutylalcohol and n-propyl-alcohol were 46.47,8.34 and 9.82 mg/L,respectively,and the content of total higher alcohols was 64.6 mg/L in the fermented liquid.The contents of methylacetate,ethyl acetate,isobutylacetate,isoamylacetate and ethylcaproate were 0.132,21.92,0.037,2.22 and 0.293 mg/L,respectively;and total ester was 24.6 mg/L.The fermentative degree of the fermented liquid and contents of diacetyl,acetaldehyde and total higher alcohols and some esters in the fermented liquid all achieved the standards of high quality beer.The sensory evaluation of the beer produced by fusant HN31-6 was nice.The fusant HN31-6 has a good prospect in the application for the beer brewing福建雪津啤酒有限公司资

Selection of Diacetyl-less Brewer Yeast and Scaling-up Fermentation

以啤酒酵母FB作为出发菌株,通过紫外线诱变,并以发酵液中双乙酰含量为主要指标筛选获得一株优良啤酒酵母UB2。三角瓶低温发酵8d,其发酵液中双乙酰含量为0.088 5mg/L,比出发菌株FB降低38％;发酵液保持了亲株FB的优良风味和凝聚性,且部分发酵性能有了较大的改善;在500L发酵罐中试实验中,UB2菌株发酵过程中的双乙酰峰值为0.17mg/L,比FB降低了45％;双乙酰还原速度较快,比FB提前1d达到质量标准,结束主酵;发酵得到的酒液经品评认为口感优于亲株。With UV mutation and selection, four strains were obtained from Saccharomyces sp. FB,which was a strain for beer brewage production. The strains were investigated in 500 mL flask with 300 mL 12° Bx wort at 12℃. After 8-day fermentation, diacetyl content, flocculence, real degree of fermentation, al-coholicity, esters and higher alcohols content of the strains were measured. The results showed That the diacetyl content of these strains was reduced, than original strain. These strains possess other choiceness properties of FB contemporary. The diacetyl content in the fermented liquid of strain UB2 was 0. 088 5 mg/L,38% less than FB, which was 0. 138 9 mg/L. Strain UB2 got a scaling-up fermentation in a 500 L tank as further test while tracking diacetyl content change in the liquid, the data showed that the peak value of the diacetyl in the fermented liquid was 0. 17 mg/L, which was 45% lower that of original strain; and the final value of diacetyl of strain UB2 was less than 0. 08 mg/L at the 7th day, which was 1 day earlier than original strain. The beer produced with UB2 was appraised, the result indicated that it's better than the beer produced with FB

Construction of a fine brewer's yeast protoplast fusant GR_5 and its fermentation characteristics

以发酵度较高的非絮凝性的啤酒酵母菌株X6和发酵度较低、絮凝性较强的啤酒酵母菌株N1为亲本进行原生质体融合。用亚硝酸诱变原养型的菌株X6,经筛选得到一株需酪素水解物的营养缺陷型菌株X6~20。采用正交试验法分别优化菌株X6~20和N1的原生质体形成和再生的条件。用X6~20菌株的原生质体作为受体和热灭活的N1菌株原生质体作为供体进行融合。融合株经三角瓶发酵筛选,得到一株较优良的融合株GR5。该融合株的絮凝性较强(本斯值为2.7),以12°Bx麦芽汁为培养基,用500 L的发酵罐在12℃下发酵,发酵至第8 d菌株GR5的发酵度为69.2%,发酵液中的双乙酰含量为0.0498 mg/L、乙醛含量为6.34 mg/L,总高级醇含量为74.4mg/L。融合株GR5具有双亲的优点,发酵的啤酒风味较好,是一株具有工业应用前景的啤酒酿造酵母菌株。Saccharomyces cerevisiae X_6 and N_1 strains were used as the parent strains for protoplast fusion.The strain X_6 was a non-flocculence strain with higher fermentation degree and the strain N_1 was a strain with lower fermentation(degree) and stronger flocculence.The auxotrophic mutant X_(6～20) required casein hydrolysate was derived from the(prototrophic) strain X_6 by treatment of nitrous acid(HNO_2) and nutritional identification.The formation and regeneration conditions of strain X_(6～20) and N_1 protoplast were optimized by orthogonal test method.The protoplast fusants were(constructed) with auxotrophic mutant X_(6～20) protoplasts for receptors and heat-inactivated strain N_1 protoplasts for(suppliers).The fusants obtained were fermented and selected.As a result a fine fusant strain GR_5 was obtained.The flocculence of fusant strain GR_5 was stronger with 2.7 mL of burns value.The content of diacetyl,acetaldehyde,total higher(alcohols) in the(fermented) liquid were 0.0498 mg/L,6.34 mg/L,74.4 mg/L,respectively,and the fermentation degree was(69.2 %) in 500 L fermentor using 12°Bx wort as the medimum at 12℃ for 8 days.The sensory evaluation of the beer produced by the fusant strain GR_5 was nice.The results showed that the fusant strain GR_5 with the fine properties from its parent strains and well(applied) prospect in the beer brewing

单重态氧发生器轻型真空储罐的研究及优化设计

单重态氧发生器是化学氧碘激光器真空条件下使用的核心部件，为减轻自重，采用碳纤维复合材料取代不锈钢制作单重态氧发生器。本文采用有限元分析方法，探索采用树脂复合材料制作真空罐体和封头的设计方法和优化方案。研究表明，其强度和真空性能均达到设计要求，为采用现代方法设计真空设备开辟新路