Chinese rice wine making is a typical simultaneous saccharification and fermentation （SSF） process. During the fermentation process, temperature is one of the key parameters which decide the quality of Chinese rice ...Chinese rice wine making is a typical simultaneous saccharification and fermentation （SSF） process. During the fermentation process, temperature is one of the key parameters which decide the quality of Chinese rice wine. To optimize the SSF process for Chinese rice wine brewing, the effects of temperature on the kinetic parameters of yeast growth and ethanol production at various temperatures were determined in batch cultures using a mathematical model. The kinetic parameters as a function of temperature were evaluated using the software Origin8.0. Combing these functions with the mathematical model, an appropriate form of the model equations for the SSF considering the effects of temperature were developed. The kinetic parameters were found to fit the experimental data satisfactorily with the developed temperature-dependent model. The temperature profile for maximizing the ethanol production for rice wine fermentation was determined by genetic algorithm. The optimum temperature profile began at a low temperature of 26℃ up to 30 h. The operating temperature increased rapidly to 31.9 ℃, and then decreased slowly to 18℃ at 65 h. Thereafter, the temperature was maintained at 18 ℃ until the end of fermentation. A maximum ethanol production of 89.3 g.L 1 was attained. Conceivably, our model would facilitate the improvement of Chinese rice wine production at the industrial scale.展开更多
Milk and water kefir have been attractive to consumers as health-promoter fermented beverages.Although both are called“kefir”,they differ in physicochemical and microbial properties.In this study,we aimed to compare...Milk and water kefir have been attractive to consumers as health-promoter fermented beverages.Although both are called“kefir”,they differ in physicochemical and microbial properties.In this study,we aimed to compare milk and water kefir in terms of biomass increase,physicochemical properties,sensory qualities,and microbial loads incubated at different incubation temperatures(20℃,25℃,and 30℃)to mimic approximate room temperatures in various seasons.Additionally,the microbial diversity of the grains was compared through metagenomic analysis.The results showed that the biomass increase,physicochemical properties,and sensory analysis of milk kefir grains depended on the fermentation temperature(p<0.05);while in general,water kefir was not affected by the fermentation temperature.The highest total dry matter,protein,and fat content,and the least acidity were recorded at 20℃ in milk kefir drinks(p<0.05).Around 8 and 6 log CFU/ml microorganism loads(Lactobacillus spp.,Lactococcus spp.,yeasts,total aerobe,and anaerobe bacteria)were recorded for milk and water kefir drinks,respectively,regardless of the temperature.Bifidobacterium load was recorded as the lowest for both kefir drinks.The dominant species of bacteria and yeasts were determined as Lactobacillus parakefiri(21.28%)and Geotricum silvicola(65.10%)in milk kefir grain,and Lactobacillus nagelii(95.69%)and Dekkera bruxellensis(95.24%)in water kefir grain,respectively.The study showed that milk and water kefir differ in terms of physicochemical,sensory,and microbial aspects.Despite its low protein content,water kefir would be a probiotic substitute for milk kefir due to its probiotic features for vegans or people with lactose intolerance.展开更多
In order to investigate the impact of low temperature on enhancing aromas in fermented dough by Pichia kudriavzevii CGMCC 17607(EP),the study initially utilized gas chromatography to detect volatile organic compounds(...In order to investigate the impact of low temperature on enhancing aromas in fermented dough by Pichia kudriavzevii CGMCC 17607(EP),the study initially utilized gas chromatography to detect volatile organic compounds(VOCs),followed by analyzing basal metabolites derived from these VOCs.Metabolomics was employed to monitor metabolic changes during fermentation,while proteomics was used to examine protein expression related to these changes.Results indicated notable increases in VOCs such as 3-methyl-1-butanol and 2-phenylethanol.Essential metabolites exhibited decreases in sugars(e.g.,sucrose,maltose),organic acids(e.g.,lactic acid,acetic acid),and amino acids(e.g.,leucine,histidine).Particularly,low temperature fermentation led to raised levels of NAD+,NADH,acyltransferases,and ATP,excluding pyruvic acid and glucose-6-phosphate dehydrogenase.These outcomes suggested that low temperature fermentation boosted acid utilization and alcohol production.Metabolomics and proteomics highlighted decreased glycolysis influencing energy metabolism.Moreover,metabolomics revealed elevated levels of flavor substances like octanoic acid and its derivatives with aromatic properties,as well as geranic acid with terpenoid aroma.Furthermore,key intermediates like chorismite and phenylpyruvic acid,along with the pivotal enzyme chorismate synthase,illustrated the biosynthesis pathway of shikimic acid instead of phenylalanine.In summary,at low temperature,EP showed weakened glycolysis,with sugars and amino acids metabolizing into desirable flavor substances like alcohols,which promoted acidity reduction and aroma enhancement of dough.展开更多
Biogas fermentation requires appropriate temperature,while the biogas fermentation can be affected by the low ambient temperature in winter.In order to overcome the negative effects of low temperature fermentation,a n...Biogas fermentation requires appropriate temperature,while the biogas fermentation can be affected by the low ambient temperature in winter.In order to overcome the negative effects of low temperature fermentation,a new type of solar heat pipe biogas fermentation heating system was designed and a preliminary experiment research on this system was conducted using cow manure as the raw material at 6%concentration and total fermentation volume of 175 L.The experimental results showed that when the system was in normal operation,the fermentation temperature rose every day by gradient.This gradient will gradually become smaller with the increase of fermentation liquid temperature,and the temperature can reach 38°C after stability.Using this solar heat pipe heating system,the fermentation liquid temperature can be increased by 5°C every sunny day.This solar heat pipe heating system plays a significant role in biogas fermentation.The results of economic analysis show that the system can realize the fermentation at constant temperatures of 25°C and 35°C respectively,and it can also save standard coal equivalent of 40 kg and 80 kg in winter and spring,respectively.展开更多
基金Supported by the National Natural Science Foundation of China(21276111,21206053,61305017)the Programme of Introducing Talents of Discipline to Universities(B12018)+2 种基金Fundamental Research Funds for the Central Universities(JUSRP11558)the Natural Science Foundation of Jiangsu Province(no.BK20160162)the Fundamental Research Funds for the Central Universities(JUSRP51510)
文摘Chinese rice wine making is a typical simultaneous saccharification and fermentation （SSF） process. During the fermentation process, temperature is one of the key parameters which decide the quality of Chinese rice wine. To optimize the SSF process for Chinese rice wine brewing, the effects of temperature on the kinetic parameters of yeast growth and ethanol production at various temperatures were determined in batch cultures using a mathematical model. The kinetic parameters as a function of temperature were evaluated using the software Origin8.0. Combing these functions with the mathematical model, an appropriate form of the model equations for the SSF considering the effects of temperature were developed. The kinetic parameters were found to fit the experimental data satisfactorily with the developed temperature-dependent model. The temperature profile for maximizing the ethanol production for rice wine fermentation was determined by genetic algorithm. The optimum temperature profile began at a low temperature of 26℃ up to 30 h. The operating temperature increased rapidly to 31.9 ℃, and then decreased slowly to 18℃ at 65 h. Thereafter, the temperature was maintained at 18 ℃ until the end of fermentation. A maximum ethanol production of 89.3 g.L 1 was attained. Conceivably, our model would facilitate the improvement of Chinese rice wine production at the industrial scale.
基金supported by the Scientific Research Projects Coordination Unit of Kirikkale University,project number 2022/017.
文摘Milk and water kefir have been attractive to consumers as health-promoter fermented beverages.Although both are called“kefir”,they differ in physicochemical and microbial properties.In this study,we aimed to compare milk and water kefir in terms of biomass increase,physicochemical properties,sensory qualities,and microbial loads incubated at different incubation temperatures(20℃,25℃,and 30℃)to mimic approximate room temperatures in various seasons.Additionally,the microbial diversity of the grains was compared through metagenomic analysis.The results showed that the biomass increase,physicochemical properties,and sensory analysis of milk kefir grains depended on the fermentation temperature(p<0.05);while in general,water kefir was not affected by the fermentation temperature.The highest total dry matter,protein,and fat content,and the least acidity were recorded at 20℃ in milk kefir drinks(p<0.05).Around 8 and 6 log CFU/ml microorganism loads(Lactobacillus spp.,Lactococcus spp.,yeasts,total aerobe,and anaerobe bacteria)were recorded for milk and water kefir drinks,respectively,regardless of the temperature.Bifidobacterium load was recorded as the lowest for both kefir drinks.The dominant species of bacteria and yeasts were determined as Lactobacillus parakefiri(21.28%)and Geotricum silvicola(65.10%)in milk kefir grain,and Lactobacillus nagelii(95.69%)and Dekkera bruxellensis(95.24%)in water kefir grain,respectively.The study showed that milk and water kefir differ in terms of physicochemical,sensory,and microbial aspects.Despite its low protein content,water kefir would be a probiotic substitute for milk kefir due to its probiotic features for vegans or people with lactose intolerance.
基金supported by the National Natural Science Foundation of China(No.32001617)the National Key R&D Program of China(2022YFF1100503,2022YFD2100300/2022YFD2100303)+1 种基金the fund of Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment&Technology(FM-202306)supported by the China Scholarship Council(CSC,No.csc 202206790003).
文摘In order to investigate the impact of low temperature on enhancing aromas in fermented dough by Pichia kudriavzevii CGMCC 17607(EP),the study initially utilized gas chromatography to detect volatile organic compounds(VOCs),followed by analyzing basal metabolites derived from these VOCs.Metabolomics was employed to monitor metabolic changes during fermentation,while proteomics was used to examine protein expression related to these changes.Results indicated notable increases in VOCs such as 3-methyl-1-butanol and 2-phenylethanol.Essential metabolites exhibited decreases in sugars(e.g.,sucrose,maltose),organic acids(e.g.,lactic acid,acetic acid),and amino acids(e.g.,leucine,histidine).Particularly,low temperature fermentation led to raised levels of NAD+,NADH,acyltransferases,and ATP,excluding pyruvic acid and glucose-6-phosphate dehydrogenase.These outcomes suggested that low temperature fermentation boosted acid utilization and alcohol production.Metabolomics and proteomics highlighted decreased glycolysis influencing energy metabolism.Moreover,metabolomics revealed elevated levels of flavor substances like octanoic acid and its derivatives with aromatic properties,as well as geranic acid with terpenoid aroma.Furthermore,key intermediates like chorismite and phenylpyruvic acid,along with the pivotal enzyme chorismate synthase,illustrated the biosynthesis pathway of shikimic acid instead of phenylalanine.In summary,at low temperature,EP showed weakened glycolysis,with sugars and amino acids metabolizing into desirable flavor substances like alcohols,which promoted acidity reduction and aroma enhancement of dough.
基金Special Fund for Agro-scientific Research in the Public Interest,Ministry of Agriculture,China(No.201403019-1)the National Natural Science Foundation of China(Grant No.U1204523)Science and technology open cooperation project of Henan Province(Grant No.152106000046).
文摘Biogas fermentation requires appropriate temperature,while the biogas fermentation can be affected by the low ambient temperature in winter.In order to overcome the negative effects of low temperature fermentation,a new type of solar heat pipe biogas fermentation heating system was designed and a preliminary experiment research on this system was conducted using cow manure as the raw material at 6%concentration and total fermentation volume of 175 L.The experimental results showed that when the system was in normal operation,the fermentation temperature rose every day by gradient.This gradient will gradually become smaller with the increase of fermentation liquid temperature,and the temperature can reach 38°C after stability.Using this solar heat pipe heating system,the fermentation liquid temperature can be increased by 5°C every sunny day.This solar heat pipe heating system plays a significant role in biogas fermentation.The results of economic analysis show that the system can realize the fermentation at constant temperatures of 25°C and 35°C respectively,and it can also save standard coal equivalent of 40 kg and 80 kg in winter and spring,respectively.
