title: Real-time monitoring of high-gravity corn mash fermentation using in situ raman spectroscopy.
abstract: In situ Raman spectroscopy was employed for real-time monitoring of simultaneous saccharification and fermentation (SSF) of corn mash by an industrial strain of Saccharomyces cerevisiae. An accurate univariate calibration model for ethanol was developed based on the very strong 883 cm(-1) C-C stretching band. Multivariate partial least squares (PLS) calibration models for total starch, dextrins, maltotriose, maltose, glucose, and ethanol were developed using data from eight batch fermentations and validated using predictions for a separate batch. The starch, ethanol, and dextrins models showed significant prediction improvement when the calibration data were divided into separate high- and low-concentration sets. Collinearity between the ethanol and starch models was avoided by excluding regions containing strong ethanol peaks from the starch model and, conversely, excluding regions containing strong saccharide peaks from the ethanol model. The two-set calibration models for starch (R(2)  = 0.998, percent error = 2.5%) and ethanol (R(2)  = 0.999, percent error = 2.1%) provide more accurate predictions than any previously published spectroscopic models. Glucose, maltose, and maltotriose are modeled to accuracy comparable to previous work on less complex fermentation processes. Our results demonstrate that Raman spectroscopy is capable of real time in situ monitoring of a complex industrial biomass fermentation. To our knowledge, this is the first PLS-based chemometric modeling of corn mash fermentation under typical industrial conditions, and the first Raman-based monitoring of a fermentation process with glucose, oligosaccharides and polysaccharides present.
authors: Department of Chemical and Biomolecular Engineering, North Carolina State University, Campus Box 7905, Raleigh, North Carolina 27695, USA.
authors: Steven R
authors: SR
authors: Gray
authors: Steven W
authors: SW
authors: Peretti
authors: H Henry
authors: HH
authors: Lamb
mesh_terms: D000704:Analysis of Variance; D056804:Biofuels / Q000032:analysis; D018533:Biomass; D019149:Bioreactors; D000431:Ethanol / Q000032:analysis* / Q000378:metabolism; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D008320:Maltose / Q000378:metabolism; D008962:Models, Theoretical; D015203:Reproducibility of Results; D013059:Spectrum Analysis, Raman / Q000379:methods*; D003313:Zea mays / Q000737:chemistry*
chemical_list: D056804:Biofuels; D000431:Ethanol; D008320:Maltose; D005947:Glucose