TY - BOOK

T1 - On-Line Monitoring of Fermentation Processes by Near Infrared and Fluorescence Spectroscopy

T2 - Elucidating and Exploring Process Dynamics

AU - Svendsen, Carina

PY - 2016

Y1 - 2016

N2 - Monitoring and control of fermentation processes is important to ensure high product yield,product quality and product consistency. More knowledge on on-line analytical techniquessuch as near infrared and fluorescence spectroscopy is desired in the fermentation industry toincrease the efficiency of on-line monitoring systems.The primary aim of this thesis is to elucidate and explore the dynamics in fermentationprocesses by spectroscopy. Though a number of successful on-line lab-scale monitoringsystems have been reported, it seems that several challenges are still met, which limits thenumber of full-scale systems implemented in industrial fermentation processes. This thesisseeks to achieve a better understanding of the techniques near infrared and fluorescencespectroscopy and thereby to solve some of the challenges that are encountered.The thesis shows the advantages of applying real-time monitoring of bioprocesses and it alsohighlights that the applied techniques with different measurement orders deliver specific butalso complementary sources of information. Furthermore, it was shown that valuable processinformation can be obtained both by near infrared spectroscopy and fluorescencespectroscopy, which provide indirect and direct measurements, respectively.Based on the measurements obtained by near infrared spectroscopy it was found that variationin scatter and in the absorption can be obtained from the same near infrared spectrum. Bykinetic modelling, it was possible to capture both physical and chemical changes appearing in alactic fermentation process. The physical changes were associated with the texturaltransformation appearing during the gel formation and chemical changes were associated withthe biological conversion reactions, which take place during the fermentation process.The results presented in this thesis also highlight that pH changes have a major effect on thefluorescence intensities, which can influence the quantifications of the relevant componentsnegatively. When the pH was either increased or decreased, manually, during the measuredprocess, a clear increase or decrease was observed in the fluorescence landscapes. This thesispresents a correction strategy based on a chemometric modelling approach, where weightednon-linear regression and weighted PARAFAC analysis are combined.Based on the research conducted in this PhD project, it is concluded that near infraredspectroscopy can provide valuable physical and chemical real-time information during yoghurtfermentation. Also, it is concluded that fluorescence data must be evaluated carefully if pHchanges appear in the measured system. Furthermore, this thesis concludes that such data stillcan be applied for on-line monitoring if corrections or preventive measures during thequantification are carried out. The findings presented in this thesis have enabled the possibilityof obtaining a better process understanding and to ease monitoring and controlling offermentation processes.

AB - Monitoring and control of fermentation processes is important to ensure high product yield,product quality and product consistency. More knowledge on on-line analytical techniquessuch as near infrared and fluorescence spectroscopy is desired in the fermentation industry toincrease the efficiency of on-line monitoring systems.The primary aim of this thesis is to elucidate and explore the dynamics in fermentationprocesses by spectroscopy. Though a number of successful on-line lab-scale monitoringsystems have been reported, it seems that several challenges are still met, which limits thenumber of full-scale systems implemented in industrial fermentation processes. This thesisseeks to achieve a better understanding of the techniques near infrared and fluorescencespectroscopy and thereby to solve some of the challenges that are encountered.The thesis shows the advantages of applying real-time monitoring of bioprocesses and it alsohighlights that the applied techniques with different measurement orders deliver specific butalso complementary sources of information. Furthermore, it was shown that valuable processinformation can be obtained both by near infrared spectroscopy and fluorescencespectroscopy, which provide indirect and direct measurements, respectively.Based on the measurements obtained by near infrared spectroscopy it was found that variationin scatter and in the absorption can be obtained from the same near infrared spectrum. Bykinetic modelling, it was possible to capture both physical and chemical changes appearing in alactic fermentation process. The physical changes were associated with the texturaltransformation appearing during the gel formation and chemical changes were associated withthe biological conversion reactions, which take place during the fermentation process.The results presented in this thesis also highlight that pH changes have a major effect on thefluorescence intensities, which can influence the quantifications of the relevant componentsnegatively. When the pH was either increased or decreased, manually, during the measuredprocess, a clear increase or decrease was observed in the fluorescence landscapes. This thesispresents a correction strategy based on a chemometric modelling approach, where weightednon-linear regression and weighted PARAFAC analysis are combined.Based on the research conducted in this PhD project, it is concluded that near infraredspectroscopy can provide valuable physical and chemical real-time information during yoghurtfermentation. Also, it is concluded that fluorescence data must be evaluated carefully if pHchanges appear in the measured system. Furthermore, this thesis concludes that such data stillcan be applied for on-line monitoring if corrections or preventive measures during thequantification are carried out. The findings presented in this thesis have enabled the possibilityof obtaining a better process understanding and to ease monitoring and controlling offermentation processes.

UR - https://soeg.kb.dk/permalink/45KBDK_KGL/fbp0ps/alma99122886432705763

M3 - Ph.D. thesis

BT - On-Line Monitoring of Fermentation Processes by Near Infrared and Fluorescence Spectroscopy

PB - Department of Food Science, Faculty of Science, University of Copenhagen

ER -