Journal ArticleDOI
Continuous lactic acid fermentation of whey to produce a ruminant feed supplement high in crude protein
A. Kent Keller,Philipp Gerhardt +1 more
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In this article, a mathematical model was developed to simulate, on a digital computer, the continuous fermentation of whey lactose to lactic acid with neutralization by ammonia, and the simulation predicted the retention times for experimental test and the use of two stages for greatest efficiency.Abstract:
A mathematical model was developed to simulate, on a digital computer, the continuous fermentation of whey lactose to lactic acid with neutralization by ammonia. The simulation predicted the retention times for experimental test and the use of two stages for greatest efficiency. In the experimental tests, Lactobacillus bulgaricus was inoculated into whey in a 14-liter continuous fermentor at 44°C and with automatic pH control. A series of steady-state conditions was managed nonaseptically for 42 days without evident contamination and with an actual increase in the efficiency of conversion. Lactic acid was produced predominately' throughout the period, with less than 0.2% of other compounds. The product contained approximately 8 times as much crude protein (N × 6.25) as the original whey. In a single-stage fermentation at pH 5.5, a retention time of 15 hr resulted in a residual lactose concentration of 0.7%; and little improvement was realized by increasing the retention time. Increasing the pH to 5.8 resulted in a significant improvement, but further increasing the pH to 6.0 resulted in only a small additional gain. By the employment of two fermentors in series at pH 5.5 with a total retention time of 31 hr, the residual lactose was reduced to less than 0.1%. Lactic acid was produced as a function mainly of maintenance rather than growth metabolism.read more
Citations
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Journal ArticleDOI
Novel Method of Lactic Acid Production by Electrodialysis Fermentation
TL;DR: It was concluded that the continuation of fermentation activity was obtained, and the productivity was three times higher than in non-pH-controlled fermentation, on account of alleviating the lactic acid inhibitory effect by electrodialysis fermentation.
Journal ArticleDOI
Lactic acid production from lactose by Lactobacillus plantarum: kinetic model and effects of pH, substrate, and oxygen
Wenge Fu,Alexander P. Mathews +1 more
TL;DR: Batch fermentation studies with no pH control indicate that lactose slightly inhibits cell growth in the exponential growth phase but there are no effects in the stationary and death phases, and a great potential for the use of L. plantarum in lactic acid fermentations for industrial applications is indicated.
Book ChapterDOI
Microbiological production of lactic acid.
TL;DR: In this paper, the authors discuss the chemical and physical properties of lactic acid followed by its commercial uses and various types of process controls are also summarized, including precipitation and acidification, centrifugation and microfiltration/ultrfiltration, distillation, ion exchange and adsorption, reverse osmosis, and solvent extraction and extractive fermentation.
Journal ArticleDOI
High‐rate continuous production of lactic acid by Lactobacillus rhamnosus in a two‐stage membrane cell‐recycle bioreactor
TL;DR: There was a distinctive difference in the production potential of cells (cell-density-related parameter in Luedeking-Piret equation) as lactic acid concentration increases over 55 g/L, and this finding led to a more precise estimation of bioreactor performance.
Journal ArticleDOI
Continuous Production of Lactic Acid from Whey Perméate by Free and Calcium Alginate Entrapped Lactobacillus helveticus
TL;DR: In this article, the authors used Lactobacillus helveticus strain milano for continuous fermentation of lactic acid in cheese whey-yeast extract permeate medium.
References
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Journal ArticleDOI
A kinetic study of the lactic acid fermentation. Batch process at controlled pH
Robert Luedeking,Edgar L. Piret +1 more
TL;DR: In this paper, the kinetics of the fermentation of glucose to lactic acid have been studied at six constant pH levels between 4·5 and 6·0 by measuring the instantaneous rates of bacterial growth and acid formation throughout each fermentation.
Journal ArticleDOI
Isolation and properties of a pure yeast polypeptidase
TL;DR: In this article, the enzyme activity of all enzyme preparations was determined by measurement of leucyldiglycine hydrolysis, and the peptidase unit employed, which was identical with the unit used in previous papers, may be defined as the amount of enzyme which will bring about 50 per cent hydrolyisation of I-peptide in 30 minutes.
Journal ArticleDOI
Limiting factors in the lactic fermentation
L. A. Rogers,E.O. Whittier +1 more
TL;DR: A microscopic count was used in order to avoid as far as possible the error introduced into the plate method by the tendency of the lactic streptococci to grow in pairs and chains.
Journal ArticleDOI
A kinetic study of the alcoholic fermentation of grape juice
TL;DR: In this article, the effect of alcohol concentration on yeast growth was studied in a continuous fermentor with a continuous yeast feed supplemented with pure alcohol at pH 3.6 and 4.05.
Journal ArticleDOI
Transient and steady states in continuous fermentaion. Theory and experiment
Robert Luedeking,Edgar L. Piret +1 more
TL;DR: In this paper, the steady-state and transient equations for continuous-flow fermentation processes are derived for single or multi-stage continuous fermentations and the criteria for stability are also examined.
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