紫外诱变筛选高耐性低产高级醇优良啤酒酵母及其高浓发酵后啤酒风味的研究

以啤酒酵母泥X为出发菌株,经筛选,得到高耐渗,高耐酒精的酵母菌Y,并与以诱变得到高耐性低产高级醇菌株MS-5,经研究发现些菌株在高耐性发酵条件下能有效降低高级醇含量。对该菌株在28°P麦芽汁培养基中的发酵性能和发酵终止时啤酒的风味物质含量进行分析,与出发菌种X及菌株Y作对比,菌株MS-5更适合于高浓酿造。     

黄酒陈酿过程中主要成分变化的研究

对不同陈酿时间的黄酒原酒进行了分析,结果表明,随黄酒酒龄的延长,黄酒主要理化指标酒精度、pH值、总酸、总糖等指标没有显著变化;总多酚在贮存期间呈下降趋势,尤其贮存前6年,降低率达到了27.6%,阿魏酸、槲皮素和原儿茶酸是引起多酚含量下降的主要原因.贮存期间,氨基酸尤其是苦味氨基酸也呈显著的下降趋势,这也是贮存期间黄酒苦涩味逐渐降低的主要原因.各种风味物质在贮存期间的变化规律不同,但总的趋势是醇和酸含量在降低,而酯类、醛类的含量在增加.5-甲基糠醛作为啤酒的老化指标,在该研究中含量从初始的3.06g/L上升到了113.34.g/L.     

毛竹笋酒发酵工艺研究

以毛竹笋加工后的剩余笋头以及鲜叶为原料,通过单因素、正交试验确定笋酒的最佳生产工艺。结果表明,毛竹笋头和毛竹鲜叶(9∶1)中加入2倍质量的水,加糖量为22%,0.3‰的安琪葡萄酒高活性干酵母,80 U/g糖化酶,60 U/g纤维素酶,30℃发酵3 d,得到酒精度13.5%vol、残总糖24.68 g/L、总酸0.62 g/L的毛竹发酵笋酒。     

四川家庭自酿葡萄酒质量现状的初步调查

在四川省内多个地区随机抽取不同年份、不同酿造工艺的家庭自酿葡萄酒样品31个,测定了其甲醇含量、二氧化硫、酒精度、菌落总数、大肠菌群和几种致病菌,还对样品进行了感官分析。结果显示,大部分样品的感官品质较差;酒精含量平均值11.61%vol（20 ℃）,有3个样品酒精含量低于7.0%vol（20 ℃）;甲醇含量平均值为0.13 g/L,所有样品甲醇含量均未超标;微生物指标检测结果符合国家标准;二氧化硫的残留量在国家标准规定的范围内。根据检测结果分析了家酿葡萄酒存在的问题,结合葡萄酒酿造原理对家酿葡萄酒操作流程提出了相应的建议,以帮助提高家庭自酿葡萄酒质量。     

美极梅奇酵母与酿酒酵母混合发酵对火龙果酒品质特性的影响

为探讨美极梅奇酵母(Metschnikowia pulcherrima,Mp)对火龙果酒品质特性的影响,Mp与酿酒酵母(Saccharomyces cerevisiae,Sc)以共接种(Mp+Sc)方式进行混合发酵,从火龙果酒基本理化指标、电子感官特性以及香气特性方面进行综合评判。同时,分析混合发酵过程中菌株生长特性和发酵特性动态变化。结果表明,混合发酵可降低火龙果酒挥发性酸含量和酸味电子感官滋味特性,增加火龙果酒挥发性酯类、醛酮类、烃类物质种类和含量,降低挥发性酸类物质的含量。随着混合发酵的不断进行,Mp菌群所占比例逐渐降低,在发酵后期,Sc逐渐成为优势菌株。发酵过程中CO2释放率表现出先增加,然后逐渐降低的趋势;而pH值则相反,表现出先降低后逐渐增加的趋势。因此,Mp主要在火龙果酒发酵前期发挥作用,与Sc混合发酵,影响火龙果酒的酸味特性和挥发性风味物质种类或含量。     

黄桃酒发酵过程中风味物质的变化

为了研究黄桃酒发酵过程中风味物质动态变化,本研究采用顶空固相微萃取(HS-SPME)结合气相色谱-质谱联用(GC-MS)技术分析风味物质,结合香气活力值(OAV)确定主要风味物质。结果表明,发酵7 d制备的黄桃酒,酒精度14.50%(v/v)、总酸31.54 g/L、可溶固形物12.37 °Brix、总黄酮1.08 g/L。感官评价表明,所制备黄桃酒保留了桃果实的清香,同时又有酒的醇香和酯香。顶空固相微萃取-气相色谱与质谱联用(HS-SPME/GC-MS)结合分析得到:发酵过程中共检测出70种风味物质,含量较多的是酯类(29种)、醇类(15种);发酵过程中风味物质种类变化不大,但每类风味物质含量却有较大变化。酯类、醇类物质含量在主发酵过程中呈递增趋势,后熟时趋稳;醛类、酮类和酸类物质含量逐渐减少。通过计算香气活力值(OAV)确定16种物质对黄桃酒风味贡献较大,其中辛酸乙酯、γ-癸内酯和右旋萜二烯对黄桃酒香气贡献最大,活力值大于20。在发酵过程中,酯类、醇类物质的增加赋予黄桃酒浓郁的酒香,同时保留了黄桃的特征香气物质。     

Characteristic of filamentous fungal diversity and dynamics associated with wheat Qu and the traditional fermentation of Chinese rice wine

Chinese rice wine, a traditional alcoholic beverage, is fermented from steamed rice with a starter culture of wheat Qu which is either inoculated spontaneously with various microorganisms in natural environment or inoculated artificially with certain microorganisms. The diversity of filamentous fungi in wheat Qu and the fermentation mashes of Chinese rice wine was studied by high‐throughput sequencing. The results indicated that filamentous fungi varied in wheat Qu and fermentation periods. Moreover, Aspergillus was the dominant filamentous fungi at genus levels. On that basis, quantitative real‐time PCR was used to quantify some dominant Aspergillus species. It was found that Aspergillus species in wheat Qu were more abundant than that in various fermentation mashes and continually decreased until the end of rice wine fermentation. Furthermore, it was found that different organic acids were produced by microorganisms at different fermentation stages might due to the changes of oxygen and nutrient content.     

DETERMINATION OF BREWING YEAST PLOIDY BY DNA MEASUREMENT

A method has been derived which permits the determination of the degree of ploidy in industrial strains of yeast. The method involves measuring the DNA content per cell of the strains, which is achieved by careful counting of the cells using a haemocytometer and a determination of the amount of DNA by a colorimetric method. Using this technique it was determined that the two industrial lager strains under investigation are tetraploid. * 1 These results have been briefly described at the meeting of the EBC Subgroup on Yeast Genetics, Copenhagen 1982.
     

响应面法优化荔枝米酒的发酵工艺

以荔枝和糯米为原料,通过Box-Behnken实验设计研究发酵温度、酵母添加量、荔枝汁添加量对荔枝米酒发酵工艺的影响,建立各影响因素的回归方程,并通过响应面分析法优化,得到了荔枝米酒发酵最佳工艺条件:发酵温度27℃、荔枝汁添加量25%、酵母添加量0.02%。进一步研究了荔枝米酒发酵过程中酒精度、还原糖含量、总酸含量的变化规律,结果表明,酒精度和还原糖含量在发酵前3d变化较大,第5d后基本保持稳定;总酸含量在整个发酵过程中变化微小。