Bioreactor Monitoring Using Non-Invasive Raman Spectroscopy

Biotechnology has had a significant impact on modern society. For example, genetically modified microorganisms are used to produce human hormones like insulin, while yeast has been used for thousands of years in the production of alcoholic drinks and other fermentation products. Additionally, wastewater undergoes biological treatment before being released back into the environment.

To ensure both the quality and safety of a final product and the successful operation of a bioreactor, one must prevent contamination and provide optimal growing conditions for the microorganisms involved. This involves monitoring various parameters such as temperature, dissolved gases, substrates, and pH. However, frequent sampling can disrupt the process and increase the risk of contamination.

Raman spectroscopy is a non-destructive, non-invasive technique that is an excellent alternative to traditional process-monitoring methods that require sampling. Raman provides real-time information on the state of the bioreactor. In our previous blog post – St. Patrick’s Day at Beer&W Tek! we demonstrated how the fermentation process is monitored using an i-Raman EX, a 1064-nm laser laboratory instrument, with RIS101 Sapphire Ball Immersion Shaft. In this post, we take the next step of performing non-invasive, stand-off monitoring of the brewing process with a RTS202 Stand-off lens (Figure 1). This allows us to gather real-time information on the state of the bioreactor without the risk of disruption or contamination.

Figure 1. i-Raman EX coupled to an RTS202 stand-off lens.

Figure 2 displays the raw Raman spectra of the beer brew from the start to roughly 9 days into the fermentation process. Despite some interference from the glass vessel, which can be mitigated by using less Raman active material, the ethanol band at 876, 1040, 1090, and 1455 cm-1 was clearly identifiable (Figure 2a). By tracking the relative intensity of the 876 cm-1 band, it is possible to monitor the increase in ethanol content of the brew throughout the fermentation process without sampling or contact (Figure 2b).

Figure 2 Raman spectra of the brew the start (red) and after 200h into the fermentation process (a) and relative intensity of the 876 cm-1 band at different phase of the fermentation process (b). 

For more information about B&W Tek’s Raman systems, visit

This entry was posted in Portable Raman Applications Videos, Applications Videos, Portable Raman and tagged , . Bookmark the permalink.