Temperature Influence in Real-Time Monitoring of Fed-Batch Ethanol Fermentation by Mid-Infrared Spectroscopy

Abstract

Fourier transform mid-infrared (FT-MIR) spectroscopy is a fast, accurate, and practical technique for the quantitative analysis of compounds during ethanol fermentation. However, it is very temperature sensitive. This study aimed to develop a methodology for the real-time monitoring of fed-batch ethanol fermentations, taking into account the thermal fluctuations in the industrial process (in the range 30−35 °C). The use of FT-MIR combined with partial least squares (PLS) regression was evaluated as a tool to quantify sucrose, glucose, fructose, ethanol, and glycerol. The PLS models, based on fermentations carried out at constant temperatures in the range from 26 to 36 °C, presented high correlation coefficients (R 2 ) and low root-mean-square errors of cross-validation and prediction that were below 7% of the calibration ranges for all compounds. The good performance of the models demonstrated their suitability for accurate process monitoring, covering a wide range of thermal variations observed in industrial operations.

Effects of Operational and Geometric Variables of a Bubble Column Bioreactor on Ethanol Stripping with CO2: Liquid and Gas-Phase Monitoring

“…The calibration models showed low RMSECV values for water (0.00114) and ethanol (0.000118). As reported in the literature, 33,34 these low RMSECV values indicated that the models presented satisfactory performance.…”

Real-Time Monitoring of Ethanol Fermentation Using Mid-Infrared Spectroscopy Analysis of the Gas Phase

“…The FT-MIR technique is an advanced and accurate tool for the determination of metabolites during ethanol fermentation. , The present approach using the gas phase to quantify ethanol overcomes the challenges related to the mode of operation and the temperature of the samples since a calibration curve is not required for each mode and the quantitation in the gas phase is independent of the reactor operating temperature. In addition, the present technique does not require sample treatment, minimizes the experimental effort in laboratory analyses, and is effective for real-time fermentation monitoring.…”

“…The quantification of liquid phase ethanol using infrared spectroscopy has been widely applied in fermentative processes such as those used for first-generation − and second-generation ethanol production, , acetone-butanol-ethanol (ABE) fermentation, and production of fermented beverages. , This method offers important advantages, compared to other techniques, since it is nondestructive and minimally invasive and enables the rapid identification and quantification of specific analytes in complex media . However, difficulties inherent to liquid phase sampling must be overcome, such as the lack of homogeneity of the samples (which are therefore not fully representative of the process), as well as the formation of gas bubbles and biofilms on the detection surface.…”

“…Therefore, there is a need for robust and specific calibration curves applicable to different operating modes (batch or fed-batch), since the temporal changes in the fermentation broth composition may differ according to the operating mode. Furthermore, the calibration model should be able to account for possible effects of temperature on quantification of the analytes, ,,, in addition to being applicable for different fermentation musts …”

Training Intensity Adjustment by Cardiac Monitoring in Young Athletes

“…The heart rate change curve is mainly for analyzing the data of the athlete's heart rate change during training with an intuitive curve rise and fall graph, the heart rate distribution graph shows the percentage of the athlete's heart rate in this training during the test time, the heart rate list can clearly see the specific heart rate value of the athlete every 5 seconds in the test phase through the data column, the heart rate segment summary shows the percentage of the athlete's heart rate under the target heart rate, within the target heart rate range, and higher than the target heart rate during the training period. 6…”