Relationship of low lysine and high arginine concentrations to efficient ethanolic fermentation of wheat mash

1992 ◽  
Vol 38 (7) ◽  
pp. 626-634 ◽  
Author(s):  
Kolothumannil C. Thomas ◽  
W. M. Ingledew
Keyword(s):  
Cell Viability ◽  
Amino Nitrogen ◽  
Nitrogen Sources ◽  
Inhibitory Effect ◽  
High Gravity ◽  
Yeast Growth ◽  
Fermentation Time ◽  
Very High Gravity ◽  
Assimilable Nitrogen ◽  
Very High

Very high gravity wheat mashes containing 20 or more grams of carbohydrates per 100 mL were fermented completely by Saccharomyces cerevisiae, even though these mashes contained low amounts of assimilable nitrogen. Supplementation of wheat mashes with various amino acids or with yeast extract, urea, or ammonium sulfate reduced the fermentation time. However, lysine or glycine added as single supplements, inhibited yeast growth and fermentation. With lysine, yeast growth was severely inhibited, and a loss of cell viability as high as 80% was seen. Partial or complete reversal of lysine-induced inhibition was achieved by the addition of a number of nitrogen sources. All nitrogen sources that relieved lysine-induced inhibition of yeast growth also promoted uptake of lysine and restored cell viability to the level observed in the control. They also increased the rate of fermentation. Experiments with minimal media showed that for lysine to be inhibitory to yeast growth, assimilable nitrogen in the medium must be in growth-limiting concentrations or totally absent. In the presence of excess nitrogen, lysine stimulated yeast growth and fermentation. Results indicate that supplementing wheat mash with other nitrogen sources increases the rate of fermentation not only by providing extra nitrogen but also by reducing or eliminating the inhibitory effect of lysine on yeast growth. Key words: very high gravity, lysine inhibition, fuel alcohol, free amino nitrogen.

scholarly journals EFFECTS OF HIGH PITCHING RATE AND NUTRITIONAL SUPPLEMENTION ON YEAST FERMENTATION PERFORMANCE IN VERY HIGH GRAVITY BREWING

2011 ◽  
Vol 14 (4) ◽  
pp. 5-15
Author(s):  
Nguyet Dang Minh Vo ◽  
Man Van Viet Le
Keyword(s):  
Ethanol Yield ◽  
Yeast Fermentation ◽  
High Gravity ◽  
Fermentation Performance ◽  
Fermentation Time ◽  
Very High Gravity ◽  
Pitching Rate ◽  
Maltose Syrup ◽  
Very High ◽  
High Gravity Brewing

In this study, the 30oBx wort with 30% maltose syrup adjunct was used for very high gravity brewing. Increase in pitching rate from 25×106 cells/mL to 125×106 cells/mL shortened the primary fermentation time and augmented the level of ethanol and diacetyl in the green beer. The suitable pitching rate was 75×106 cells/mL. Under this condition, the fermentation time reduced 44.2% and the ethanol concentration in the green beer increased 13.7% in comparison with those in the culture with conventional pitching rate; the ethanol yield achieved maximum of 44.1%. Combination of high pitching rate and nutritional supplementation to 30oBx wort reduced the fermentation time 8.7% and maintained the similar ethanol content in the green beer and the similar ethanol yield in comparison with the high pitching rate culture.

scholarly journals Redox potential driven aeration during very-high-gravity ethanol fermentation by using flocculating yeast

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Chen-Guang Liu ◽  
Xue-Mi Hao ◽  
Yen-Han Lin ◽  
Feng-Wu Bai
Keyword(s):  
Cell Viability ◽  
Redox Potential ◽  
Ethanol Fermentation ◽  
Anaerobic Fermentation ◽  
Oxygen Demand ◽  
High Gravity ◽  
Very High Gravity ◽  
Flocculating Yeast ◽  
Aeration Process ◽  
Very High

Abstract Ethanol fermentation requires oxygen to maintain high biomass and cell viability, especially under very-high-gravity (VHG) condition. In this work, fermentation redox potential (ORP) was applied to drive the aeration process at low dissolved oxygen (DO) levels, which is infeasible to be regulated by a DO sensor. The performance and characteristics of flocculating yeast grown under 300 and 260 g glucose/L conditions were subjected to various aeration strategies including: no aeration; controlled aeration at −150, −100 and −50 mV levels; and constant aeration at 0.05 and 0.2 vvm. The results showed that anaerobic fermentation produced the least ethanol and had the highest residual glucose after 72 h of fermentation. Controlled aerations, depending on the real-time oxygen demand, led to higher cell viability than the no-aeration counterpart. Constant aeration triggered a quick biomass formation, and fast glucose utilization. However, over aeration at 0.2 vvm caused a reduction of final ethanol concentration. The controlled aeration driven by ORP under VHG conditions resulted in the best fermentation performance. Moreover, the controlled aeration could enhance yeast flocculating activity, promote an increase of flocs size, and accelerate yeast separation near the end of fermentation.

scholarly journals Novel Effective Yeast Strains and Their Performance in High Gravity and Very High Gravity Ethanol Fermentations from Sweet Sorghum Juice

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 557
Author(s):  
Lakkana Laopaiboon ◽  
Suntaree Suporn ◽  
Preekamol Klanrit ◽  
Niphaphat Phukoetphim ◽  
Chalida Daengbussadee ◽  
...  
Keyword(s):  
Ethanol Production ◽  
Sweet Sorghum ◽  
Production Efficiency ◽  
Total Sugar ◽  
High Gravity ◽  
Fermentation Time ◽  
Very High Gravity ◽  
Sweet Sorghum Juice ◽  
Sugar Cane Juice ◽  
Very High

Yeasts were isolated from four potential sources, sweet sorghum juice, sugar cane juice, grapes and rambutan. The 27 yeast isolates were tested for their ethanol tolerance (15% v/v of ethanol) and ethanol fermentation performance in a synthetic ethanol production medium (200 g/L of total sugar). Only five isolates, SCJ04KKU, SCJ07KKU, SCJ09KKU, SCJ14KKU and SSJ01KKU could tolerate 15% ethanol and produce ethanol at levels higher than 55 g/L. The ethanol production efficiency from sweet sorghum juice under high gravity (HG, 200 and 240 g/L of total sugar) and very high gravity (VHG, 280 g/L of total sugar) conditions of the five isolates was tested. Saccharomyces cerevisiae NP01 and S. cerevisiae ATCC4132 were used as reference strains. The results showed that the SSJ01KKU isolate gave the highest ethanol production efficiency under all conditions. Ethanol concentration (PE), yield (YP/S) and productivity (QP) values were 98.89 g/L, 0.50 and 1.18 g/L·h, respectively, with sugar consumption (SC) of 98.96% under the HG condition at 200 g/L of total sugar. Under the HG condition at 240 g/L of total sugar, the PE, YP/S and QP values were 118.12 g/L, 0.51 and 1.41 g/L·h, respectively, with the SC of 95.79%. These values were 82.29 g/L, 0.34 and 0.98 g/L·h, respectively, with the SC of 85.59% under the VHG condition. Addition of urea into the sweet sorghum juice under all conditions significantly shortened the fermentation time, resulting in increased QP values. Based on molecular taxonomic analysis of the five isolates using sequence analysis of the D1/D2 domain and the ITS1 and ITS2 regions, SSJ01KKU is S. cerevisiae, whereas SCJ04KKU, SCJ07KKU, SCJ09KKU and SCJ14KKU are Pichia caribbica.

Selection of stress-tolerant yeasts for simultaneous saccharification and fermentation (SSF) of very high gravity (VHG) potato mash to ethanol

2010 ◽  
Vol 101 (24) ◽  
pp. 9710-9714 ◽  
Author(s):  
Takashi Watanabe ◽  
Sathaporn Srichuwong ◽  
Mitsuhiro Arakane ◽  
Seiji Tamiya ◽  
Masaru Yoshinaga ◽  
...  
Keyword(s):  
Simultaneous Saccharification And Fermentation ◽  
High Gravity ◽  
Very High Gravity ◽  
Very High ◽  
Simultaneous Saccharification ◽  
Selection Of
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