苹果酒酵母融合子W1发酵工艺参数的优化研究

该文利用所构建的苹果酒的模糊综合评判模型,以评判结果为目标,采用响应界面法研究了苹果酒发酵的规律,建立了优质苹果酒发酵的二次多项式数学模型,同时验证了模型的有效性,并考察了接种量、初始pH值和发酵温度对苹果酒品质的影响,优化出最佳发酵工艺参数为接种量5.33%、初始pH值3.37、发酵温度22.14℃。     

基于模糊综合评判的石佛寺人工湿地水质评价

利用线性隶属函数确定各单项指标隶属度,采用单纯阈值法中倒数法确定权重,构建了模糊综合评判数学模型。并运用该模型对石佛寺人工湿地水质进行了评价与分析,结果表明:出口水质等级均低于入口,且汛期净化效果好于非汛期,说明人工湿对水体具有良好的净化效果。     

乡镇企业节能项目的计算机模糊层次综合评判

运用多目标模糊层次分析法,构建了乡镇企业节能项目综合评价指标体系和评判模型,研究了评判指标的隶属函数、隶属度确定的数值算法及合成算法,用Visual Basic6.0设计了计算机评判软件系统,并通过典型案例进行了应用验证,结果表明:所建指标体系从技术、经济和社会生态环境三方面客观、真实地反映了节能项目的综合效果;所建评判模型反映了节能项目综合评判的模糊性、综合性和多层次性,为评判项目的整体优劣和投资决策提供了依据     

基于主成分分析法的苹果酒香气质量评价模型的构建

利用顶空法固相微萃取与气相色谱质谱联用(HS-SPME-GC-MS)测定了12种苹果酒中的部分重要香气成分,利用主成分分析法建立了苹果酒香气质量评价模型,并用该模型对12种苹果酒香气质量进行了评价,结果表明苹果酒S12的香气质量最好;进一步通过感官评价法对模型评价结果进行了检验,结果表明2种方法具有很好的一致性,表明该文提出的方法是可行的,为果酒香气质量的评价探索了一种新的途径。     

绿色食品生产基地环境质量综合评价 — — 以黑龙江省庆安县为例

对不同环境因子采用不同评判方法 ,利用模糊评判法模糊推理以及定性与定量结合 ,综合评价了绿色食品原料生产基地生态环境质量 ,并通过反复验证确定了适合的隶属函数 ,其方法可行 ,结果可信 ,可推广至其他绿色食品生产基地环境质量的评价     

农业投资项目区的模糊综合评选

本文应用模糊综合评判方法构造了项目区指标的隶属函数，对农业投资项目区进行综合评选，评选结果与实际相吻合。     

啤酒感官质量的计算机模糊综合评判

在啤酒GB4927—91质量标准基础上,建立了啤酒感官质量标准的一级模糊综合评判模型,提出并设计出适合计算机模糊综合评判的数值算法,用此算法设计的一级模糊综合评判FOR—TRAN语言处理程序,经过FACOMM34OS计算机上的实际运行,与实际评判结果具有很好的一致性,而且使得评判结果更为准确。     

三峡库区农业生态系统综合评价研究

采用Delphi法与AHP法相结合方法,研究建立了三峡库区农业生态系统综合评价指标体系;并通过建立模糊隶属函数模型和确定评价指标标准值,对重庆市丰都县包鸾农业综合开发区农业生态系统进行模糊综合评判,结果表明该区农业生态系统综合效益较差,亟待改进;其3大效益社会效益>生态效益>经济效益,这与实际情况相符。     

辽宁省东部山区5种森林植被类型水文生态效益综合评判

利用层次分析与Fuzzy数学相结合方法,对辽宁省东部山区5种森林植被类型水源涵养能力进行了多目标综合评判。首先利用层次分析法确定了评价因子林冠截留、林冠蒸散、枯落物蓄水、土壤容重、非毛管孔隙度、初渗速率、稳渗速率、土壤总蓄水和土壤有效水的权重集为C=(0.0245,0.0051,0.1993,0.0109,0.0762,0.0565,0.2827,0.0573,0.2866),然后利用最大模糊熵原则确定了评价因子的隶属函数,最后利用Fuzzy综合评判得出油松、落叶松、红松、柞木林、杂木林评价结果模糊子集为B=(0.4686,0.3784,0.4145,0.6128,0.4808),结果表明阔叶林水源涵养效益高于针叶林,其中柞木林效益最佳。     

云南昭通滑坡泥石流危险度模糊综合评判

探讨了云南昭通的滑坡、泥石流詹工模糊综合评判法，介绍了以概率代替隶属频率，并构成单因素模糊矩阵Ｒ．以此为基础，完成了昭通滑坡、泥石流危险度分区。     

Sensory and analytical study of rose sparkling wines manufactured by second fermentation in the bottle

The sensory and analytical characteristics of five rose sparkling wines manufactured by the traditional method have been determined. Moreover, the changes that take place in the nitrogen and volatile fraction of the wines during the second fermentation and the aging with the yeasts have been studied. Each of these wines was made from a single industrial rose base wine of the Garnacha Tinta variety, with five selected yeasts strains. The base wine had a low content in free amino acids, 16 mg/L, and the yeast consumed more peptides than free amino acids during second fermentation. From the application of the two-way analysis of variance, yeast strain, and aging time factors to the data of volatile compounds, it has been found that most of the differences between these sparkling wines are due to the aging time. It has been verified that these rose sparkling wines have foam of good quality and that the grape variety Garnacha Tinta is suitable for the production of rose sparkling wines.     

Stability of patulin to sulfur dioxide and to yeast fermentation.

The affinity of patulin for sulfur dioxide (SO2) is much less than was previously reported and is of little significance at the SO2 concentrations (below 200 ppm) used in the processing of apple juice and cider. However, at concentrations of 2000 ppm SO2 and 15 ppm patulin, combination was 90% complete in 2 days. Removal of SO2 liberated only part of the patulin, which suggests that 2 mechanisms are involved: one reversible (opening the hemiacetal ring) and one irreversible (SO2 addition at the double bond). Test with 2 yeasts used in English commercial cider making confirmed that patulin is effectively removed during yeast fermentation.     

Yeast influence on volatile composition of wines.

Nine Saccharomyces cerevisiae and four Saccharomyces bayanus strains used in the production of Trebbiano wine were examined. The aim of this study is to evaluate the different abilities of various yeast strains in wine-making. The possibility of yeast discrimination on the basis of their volatile production is another possibility. Wine chemical analyses showed statistically significant differences depending on the yeast strain used. Some compounds such as 2-phenylethanol, 2-phenethyl acetate, ethyl lactate, 3-ethoxypropanol, and, to a lesser extent, diethyl succinate and propionic acid characterized examined Saccharomyces bayanus yeasts. Moreover, these strains did not produce any undesirable compounds, such as acetic acid and sulfur anhydride. For these reasons and because they synthesized malic acid, they could be more suitable for white wine production. The other yeasts showed great differences, which are difficult to correlate with the strain. However, some strains had peculiar characteristics, such as an uncommonly high concentration of n-propanol and 3-ethoxypropanol.     

New Saccharomyces cerevisiae baker's yeast displaying enhanced resistance to freezing

Three procedures were used to obtain new Saccharomyces cerevisiae baker's yeasts with increased storage stability at -20, 4, 22, and 30 degrees C. The first used mitochondria from highly ethanol-tolerant wine yeast, which were transferred to baker's strains. Viability of the heteroplasmons was improved shortly after freezing. However, after prolonged storage, viability dramatically decreased and was accompanied by an increase in the frequency of respiratory-deficient (petite) mutant formation. This indicated that mitochondria were not stable and were incompatible with the nucleus. The strains tested regained their original resistance to freezing after recovering their own mitochondria. The second procedure used hybrid formation after protoplast fusion and isolation on selective media of fusants from baker's yeast meiotic products resistant to parafluorphenylalanine and cycloheximide, respectively. No hybrids were obtained when using the parentals, probably due to the high ploidy of the baker's strains. Hybrids obtained from nonisogenic strains manifested in all cases a resistance to freezing intermediate between those of their parental strains. Hybrids from crosses between meiotic products of the same strain were always more sensitive than their parentals. The third method was used to develop baker's yeast mutants resistant to 2-deoxy-d-glucose (DOG) and deregulated for maltose and sucrose metabolism. Mutant DOG21 displayed a slight increase in trehalose content and viability both in frozen doughs and during storage at 4 and 22 degrees C. This mutant also displayed a capacity to ferment, under laboratory conditions, both lean and sweet fresh and frozen doughs. For industrial uses, fermented lean and sweet bakery products, both from fresh and frozen doughs obtained with mutant DOG21, were of better quality with regard to volume, texture, and organoleptic properties than those produced by the wild type.     

Rhodamine-pink as a genetic marker for yeast populations in wine fermentation

Winemaking with selected yeasts requires simple techniques to monitor the inoculated yeast. New high-concentration rhodamine-resistant mutants and low-concentration rhodamine-pink mutants, easy to detect by replica-plate assay, were obtained from selected wine yeasts. The rhodamine-pink mutations were dominant and were located at the pdr5 locus that encodes for the Pdr5 ATP-binding cassette multidrug resistance transporter. The mutants were genetically stable but had lost the killer phenotype of the parent yeast strain. They were genetically improved by elimination of recessive growth-retarding alleles followed by crossing with selected killer wine yeasts. Several spore-clones were selected according to their must fermentation kinetics and the organoleptic quality of the wine. Some spore-clones were tested in industrial winemaking, and they were easily monitored during must fermentation using a simple color-plate assay. They accounted for >96% of the total yeasts in the must, and the resulting wine had as good a quality as those made with standard commercial wine yeasts. The rhodamine-pink yeasts may also be detected by direct seeding onto rhodamine agar or by observation under fluorescence microscopy. These possibilities greatly reduce the time of analysis and make the monitoring procedure for rhodamine-pink yeasts faster, easier, and cheaper than for the genetically marked wine yeasts obtained previously.     

酵母对冷冻面团发酵特性及馒头品质的影响

为了找出使冷冻面团和馒头综合品质较稳定的酵母产品,采用动态流变仪和F3发酵仪对低糖型国光高活性干酵母(1#)、英联马利苹果即发高活性干酵母(2#)、品一高活性干酵母(3#)、高糖型马利即发高活性干酵母(4#)、高糖型丹宝利即发高活性干酵母(5#)和耐高糖安琪高活性干酵母(6#)冷冻面团冻藏35 d过程中的流变学特性和发酵特性进行研究,并对由此面团制作馒头的质构、色泽、比容和感官品质进行分析。结果表明:不同市售酵母冷冻面团在不同冻藏时间下的流变学特性和发酵特性不同。不同酵母冷冻面团制作馒头后硬度、弹性、回复性、咀嚼性、亮度、红度、黄度、比容和感官品质分别差异显著,不同冻藏时间下同种酵母冷冻面团馒头的质构、色泽、比容和感官品质也分别差异显著。6种酵母在冻藏35 d内,1#和2#酵母冷冻面团的发酵活力始终较大,6#酵母冷冻面团的发酵特性参数始终最稳定;1#、5#和6#酵母冷冻面团的弹性模量与黏性模量较大,其中面团流变学特性最稳定的是5#;1#和6#酵母冷冻面团制作馒头的感官品质较好的同时,比容较高,色泽品质较好,质构品质也较好。因此整个冻藏期间,使冷冻面团和馒头综合品质较好较稳定的是1#,其次是6#。研究结果为冷冻面团馒头工业化生产中酵母的选择提供参考。     

区域地下水资源承载力综合评价研究

利用模糊综合评价法 ,建立了区域地下水资源承载力的综合评价模型。并以关中平原为例 ,对该区地下水资源承载力进行了分析评价 ,评价结果合理、可靠。并提出了相应的开发对策     

Release of lipids during yeast autolysis in a model wine system

The release of lipids during the aging of sparkling wines in contact with yeast can influence wine sensory attributes and, especially, foam characteristics. Model systems allow study of the autolysis process in a reasonable period of time compared to natural conditions, at which it can last several months. In this paper, the release of the different classes of lipids during the autolysis of three commercial yeast strains in a model wine medium has been monitored. Due to the absence of accurate quantitative methods, an HPLC method for separating and quantifying the different neutral and polar yeast lipid classes was developed. Lipids were eluted through a YMC PVA-Sil column with a complex solvent mixture. Detection was carried out with a light-scattering detector. The yeasts were suspended in the model wine buffer and incubated at 30 degrees C for up to 12 days. A release of triacylglycerols, 1,3-diacylglycerols, 2-monoacylglycerols, free fatty acids, sterol esters, and sterols was observed over the first 2 days, a period that corresponded to the maximum loss of yeast viability. A decrease in most of these lipids was observed from day 2, possibly indicative of the release of yeast hydrolytic enzymes due to the breakdown of the cell wall. Phospholipids were not detected in any of the autolysates. The mean lipid content in the autolysates as a percentage of the total lipid content in the yeasts was 8.6% for sterol esters, 3.8% for sterols, 2% for triacylglycerols, and <2% for 1,3-diacylglycerols and free fatty acids.     

Sulfometuron resistance as a genetic marker for yeast populations in wine fermentations

Winemaking with selected yeasts requires simple and cheap techniques to monitor the yeast population dynamics. We obtained new sulfometuron (smr) resistant mutants, easy to detect by replica-plate assay, from selected wine yeasts. The mutations were dominant and were located at the ilv2 locus that encodes for acetolactate synthase enzyme. The mutants were genetically stable and maintained the killer phenotype of the parent yeast strain. They were genetically improved by elimination of recessive growth-retarding alleles followed by spore clone selection according to the must fermentation kinetics and the organoleptic quality of the wine. Some mutants were tested in industrial winemaking and were easily monitored during must fermentation using a simple plate assay. They accounted for more than 95% of the total yeasts in the must, and the resulting wine had as good a quality as those made with standard commercial wine yeasts.