15A-10 |
The performance of FTIR and FT-Raman spectroscopic techniques in simultaneous monitoring of multiple components in a Lactobacillus casei production process |
S. SAKHAMURI, J. M. K. Irudayaraj, and A. Demirci. Dept. of Agricultural & Biological Engineering, The Pennsylvania State Univ., 109 Agricultural Engineering Bldg., University Park, PA 16802 Control and optimization of fermentation processes is based on an ability to accurately measure parameters such as substrate and product levels, and cell mass. Infrared spectroscopic techniques can potentially be used to measure multiple components with in 2 minutes of sampling, using an unprocessed whole broth sample. In the present study the use of different infrared spectroscopic techniques for rapid off-line monitoring of biomass, lactic acid, and glucose in a Lactobacillus casei process was investigated. The results obtained with different infrared spectroscopic techniques were compared with samples analyzed using HPLC. The main objective is to develop a rapid and simple FTIR and FT-Raman procedure and a suitable calibration model to detect glucose, lactic acid, and optical cell density during the fermentation. FTIR spectra were recorded on a spectrometer equipped with deuterated tryiglycine sulphate detector with an attenuated total reflectance accessory. FT-Raman spectra were obtained using a HeNe laser operating at 1064 nm with a maximum power of 2 W. The spectral data were correlated with HPLC data using multivariate statistical analysis such as partial least square and principal component regression methods. The concentrations glucose and lactic acid, and optical cell density of L. casei during ethanol fermentation were measured simultaneously by FTIR spectroscopy without any sample preparation. Validation results show that the FTIR spectroscopic technique could accurately predict the concentration of glucose and ethanol though the R2 for optical cell density is low. FT-Raman spectroscopy is suitable for analysis of major constituents in bioprocesses when they are present at high concentrations. The developed method can be used to measure other chemical components in the culture medium such as salts by noninvasive methods. At-line infrared analysis has been shown to have considerable potential for fermentation process improvement by improved monitoring and process control.
Session 15A, Biotechnology
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