工业黄酒生产中酒母发酵自动温控的研究与应用

目前工业黄酒生产中酒母发酵温控多为手动操作,存在温度波动大、批次稳定性差等问题。利用DCS控制系统,模拟人工温控方式,实现自动温控。现场实验结果表明,该方式运行稳定,不仅满足生产工艺要求,还改善了控制效果。

影响酒母质量的因素

影响酒母质量的因素徐开成，吕承广山东省淄博商校２５５０２２酒精发酵是食醋生产中的重要环节，其作用是把曲霉分解产生的葡萄糖发酵生成酒精、ＣＯ２及其它副产物，为醋酸发酵打好基础，对连续生产有重要作用。酒母产酒精发酵的动力，酒母的质量直接影响到酒精发酵的效...

Improve Ethanol Yield Through Minimizing Glycerol Yield in Ethanol Fermentation of Saccharomyces cerevisiae

In ethanol fermentation of Saccharomyces cerevisiae （S. cerevisiae）, glycerol is one of the main by-products. The purpose of this investigation was to increase ethanol yield through minimizing glycerol yield by using mutants in which FPS1 encoding a channel protein that mediates glycerol export and GPD2 encoding one of glycerol-3-phosphate dehydrogenase were knocked-out using one-step gene replacement. GLT1 and GLN1 that encode glutamate synthase and glutamine synth.etase, respectively,were overexpressed using two-step gene replacment in fpsl△gpd2△ mutant.The fermentation properties of ZAL69（fpsl△：：LEU2 gpd2△：：URA3） and ZAL808 （fps1△：：LEU2 gpd2△：：URA3 PPGK1-GLT1 PPGK1-GLN1） under microaerobic conditions were investigated and compared with those of wild type（DC124）. Consumption of glucose, yield of ethanol, yield of glycerol, acetic acid, and pyruvic acid were monitored. Compared with wild type, the ethanol yield of ZAL69 and ZAL808 were improved by. 13.17% and 6.66 %, respectively, whereas glycerol yield decreased by 37.4 % and 41.7 %. Meanwhile, acetic acia yield and pyruvic acid yield aecreasea aramatlcally comparea to wild type. Our results indicate that FPS1 and GPD2 deletion of S. cerevisiae resulted in reduced glycerol yield and increased ethanol yield, but simultaneous overexpression of GLT1 and GLN1 infps1△gpd2△ mutant did not have a higher ethanol yield thanfps1△gpd2△ mutant.

Effect of Propanoic Acid on Ethanol Fermentation by Saccharomyces cerevisiae in an Ethanol-Methane Coupled Fermentation Process

Propanoic acid accumulated in an ethanol-methane coupled fermentation process affects the ethanol fermentation by Saccharomyces cerevisiae. The effects of propanoic acid on ethanol production were examined in cassava mash under different pH conditions. Final ethanol concentrations increased when undissociated propanoic acid was <30.0 mmol·L-1 . Propanoic acid, however, stimulated ethanol production, as much as 7.6% under proper conditions, but ethanol fermentation was completely inhibited when undissociated acid was >53.2 mmol·L-1 . Therefore, the potential inhibitory effect of propanoic acid on ethanol fermentation may be avoided by controlling the undissociated acid concentrations through elevated medium pH. Biomass and glycerol production decreased with propanoic acid in the medium, partly contributing to increased ethanol concentration.

Effects of Different Microbes on Fermenting Feed for Sea Cucumber(Apostichopus japonicus)

The effects of different microbes on fermenting feed for sea cucumber （Apostichopus japonicus） were compared to select the optimal fermentation strain in this study. Saccharomgces cerevisae, Candida utilis, Bacillus subtilis and Geotrichum candidum were independently added into the experimental compound feed, while only saline was mixed with the control feed. The fermentation treatments were inoculated with 10% seed solution under the condition of 25 ~C and 70% water content, which lasted for 5 days to elucidate the optimal microbe strain for fermenting effect. Physicochemical indexes and sensorial characteristics were measured per day during the fermentation. The indexes included dry matter recovery （DMR）, crude protein （CP）, the percentage of amino acid nitrogen to total nitrogen （AA-N/tN）, the percentage of ammonia nitrogen to total nitrogen （NH3-N/tN）, and the ratio of fermentation strains and vibrios to the total microbes, color, smell and viscosity. The results showed that DMR, CP and AA-N/tN of the S. cerevisae group reached the highest level on day 3, but the ratio of fermentation strain was second to C. utilis group. In addition, its NH3-N/tN and the ratio of vibrios were maintained at low levels, and the sensory evaluation score including smell, color and viscosity was the highest in S. cerevisae group on day 3. Therefore, S. cerevisae could be the optimal strain for the feed fermentation for sea cucumber. This research developed a new production method of fermentation feed for sea cucumber.

Elementary Flux Mode Analysis for Optimized Ethanol Yield in Anaerobic Fermentation of Glucose with Saccharomyces cerevisiae

Elementary flux mode （EFM） analysis was used in the metabolic analysis of central carbon metabolism in Saccharomyces cerevisiae based on constructed cellular network. Calculated from the metabolic model, the ethanol-producing pathway No. 37 furthest converts the substrate into ethanol among the 78 elementary flux modes. The in silico metabolic phenotypes predicted based on this analysis fit well with the fermentation performance of the engineered strains, KAM3 and KAMll, which confirmed that EFM analysis is valid to direct the construction of Saccharomyces cerevisiae engineered strains, to increase the ethanol yield.

Hydrolysis of Banana Tree Pseudostem and Second-Generation Ethanol Production by Saccharomyces Cerevisae

The alcoholic fermentation of substrates rich in free soluble sugars is well known and has been industrially developed. However, the production of second-generation ethanol from lignocellulosic biomass, which is abundantly available worldwide, remains under development. The aim of this study was to evaluate the possibility of using the Musa cavendischii banana tree pseudostem as a substrate for alcoholic fermentation. Hydrolisis methods using dilute sulfuric acid （1% and 2% H2SO4; 15 and 30 min; 90 ℃, 100 ℃ and 120 ℃） and enzymes （pH 5.5; and 45 ℃ for 24 h reaction time） were evaluated both separately and in combination. The effect of chemical pre-treatment of the substrate using 1% and 3% m/m NaOH （120 ℃, 15 min） was verified for both methods. The highest yield coefficient of fermentable sugars from dry biomass （Yrs = 74%） was obtained using enzymatic hydrolysis and pre-treatment with 3% NaOH. Using acid hydrolysis, the maximum yield obtained was 22% （1% H2SO4, 120 ℃, 30 min）. Fermentation of the hydrolysates was satisfactory, and the maximum yield of ethanol formed per unit of substrate consumed, total productivity and efficiency values were 0.35 g, 0.90 g ethanol L^-1·h^-1 and 65.9%, respectively. This demonstrates the utility of banana tree pseudostems in second-generation ethanol production.

Application Prospects for the Innovation of Defined Fungal Starter in Rice Wine Fermentation

The feasibility of pilot-scale manufacture of defined fungal starter and its application in rice wine production from different local starchy materials were investigated. Starter consisting of Arnylomyces rouxii and Saccharomyces cerevisiae gave high performance in winemaking when prepared in conditions of rice flour 80% and cassava flour 20% with 4 incubation days. The starter level at 20% was favourably employed for manufacture with the initial amount of I0 kg mixed-flours, Dry starter granules which were vacuum packed could adapt ambient temperature （approx. 28-32℃） during 8 months of storage. The defined starter performed as superior inoculum for winemaking from different agricultural starchy resources. The undesirable bacteria were found at approx. 2 Log CFU/g of dry starter. By morphology, biochemical and physiological growth and the genetic partial 16S analyses, three bacterial isolates were characterized as Bacillus subtilis/amvloliquefaciens which may contaminate tbod but not cause food poisoning and not considered as a human pathogen.

Rumen fermentation and acetogen population changes in response to an exogenous acetogen TWA4 strain and Saccharomyces cerevisiae fermentation product

The presence of yeast cells could stimulate hydrogen utilization of acetogens and enhance acetogenesis. To understand the roles of acetogens in rumen fermentation, an in vitro rumen fermentation experiment was conducted with addition of acetogen strain （TWA4） and/or Saccharomyces cerevisiae fermentation product （XP）. A 2×2 factorial design with two levels of TWA4 （0 or 2×10^7 cells/ml） and XP （0 or 2 g/L） was performed. Volatile fatty acids （VFAs） were increased （P〈0.05） in XP and TWA4XP, while methane was increased only in TWA4XP （P〈0.05）. The increase rate of microorganisms with formyltetrahydrofolate synthetase, especially acetogens, was higher than that of methanogens under all treatments. Lachnospiraceae was predominant in all acetogen communities, but without close acetyI-CoA synthase （ACS） amino acid sequences from cultured isolates. Low-Acetitomaculum ruminis-like ACS was predominant in all acetogen communities, while four unique phylotypes in XP treatment were all amino acid identified Iow-Eubacterium limosum-like acetogens. It differs to XP treatment that more Iow-A. ruminis-like and less Iow- E. limosum-like sequences were identified in ＂I＇WA4 and TWA4XP treatments. Enhancing acetogenesis by supple- mentation with an acetogen strain and/or yeast cells may be an approach to mitigate methane, by targeting proper acetogens such as uncultured Iow-E. limosum-like acetogens.