The concern for the development of alternative and renewable fuels has increased over the past several years. Bioethanol is a good replacement for fossil fuels. It can be made from items like sugar, starch, or lignocellulosic biomass, such as kernel corn.

Global ethanol production exceeded 28 billion gallons in 2022 [1]. Ethanol is mainly produced via the process of fermentation. Fermentation transforms sugars within the biomass into ethanol through the use of yeast.

It is well known that the quality of the feedstock can vary from season to season which requires ethanol producers to adapt to each batch. With the use of inline near-infrared spectroscopy (NIRS), several fermentation quality parameters can be monitored simultaneously directly in the tank, as shown in this Process Application Note.

To guarantee high yield and top-quality ethanol, many parameters should be monitored during ethanol production. Traditionally, the amount of reactants, products, and byproducts are measured in the laboratory after taking a sample out of the process. However, manual laboratory methods can result in long response times in case of process changes (e.g., temperature, reaction mixture, moisture levels), and sample preparation (dilution, filtration, pipetting) can introduce errors altering the precision of the analysis.

Additionally, it can be quite cumbersome since multiple techniques and/or operating methods are required to analyze the following parameters: ethanol, dextrin (DP4), maltotriose (DP3), maltose, glucose, lactic acid, glycerol, and acetic acid (Table 1), along with moisture and solids (enzymes).

In any chemical process, «real-time» monitoring allows for optimal process modeling and control, which means enhanced throughput, reproducibility, and productivity.

For instance, tight monitoring and control over the various sugars present (glucose, maltose, DP3, and DP4) throughout the fermentation process is necessary to understand the breakdown pathway of the starch (glucose generation) present in the mash and optimize ethanol production [2]. Understanding the sugar pathway enables the right dosing of «enzymatic mix» and «yeast blend» to the mash in the slurry tanks to accelerate breakdown [3].

For optimal fermentation, multiple parameters must be monitored in a safer, more efficient, and faster manner, which is possible via inline analysis with reagent-free near-infrared spectroscopy (NIRS) (Figure 2). Metrohm Process Analytics offers the 2060 The NIR Analyzer (Figure 3) which enables direct comparison of «real time» spectral data from the process to a reference method (e.g., HPLC) to create a simple yet indispensable calibration model used to produce quantitative results during the fermentation process.

Traditional analysis methods do not provide sufficient «real-time» information about the fermentation process performance for bioethanol production. Inline analysis with NIRS can provide faster information about the fermentation process, which is ideal for rapid feedback (approximately every 30 seconds) and higher process throughput.

NIRS analysis allows for the comparison of real-time spectral data with a primary method (e.g., titration, Karl Fischer titration, HPLC, IC) to develop a straightforward yet essential model for meeting fermentation process needs. Enhance and improve production management using the Metrohm Process Analytics 2060 The NIR Analyzer, which grants even greater fermentation control by monitoring up to five process points per NIR cabinet with the multiplexer option.