Fermentation with yeast is one of the oldest biotechnological processes used by mankind. Methods to control and analyze cell growth and development are standard but still more information can be unlocked. To control and improve fermentation processes, yeast viability and cell density are crucial variables.
Amphasys provides with its technology based on Impedance Flow Cytometry a method for an efficient analysis in yeast propagation and pitching, as well as monitoring fermentation and production process. Our Ampha X30 cell analyzer enables highly accurate determination of cell viability, concentration, metabolism, and cell health status.
- Label free, no staining procedures, no markers needed, no incubation
- Simultaneous analysis and result of cell count and cell viability – among other cell properties
- Highly sophisticated software for advanced data analysis
- Short sample preparation and measurement times
- Low operational cost
- No impact of turbidity and particles
- No calibrations, no adjustments
- Online measurements via bypass
Case study: Beer Fermentation
Yeast viability can be affected by various factors, such as temperature, pH, and the presence of contaminants. High viability means that a large percentage of the yeast cells are active and able to perform fermentation, while low viability means that fewer cells are active, and the fermentation process may be slowed or halted. It is important to use healthy and viable yeast for fermentation to achieve optimal results. Additionally, a higher yeast concentration will result in a faster fermentation, while a lower yeast concentration will result in a slower fermentation.
The fermentation of beer was monitored over a course of seven days. In parallel, cell viability and cell concentration were determined. In addition to dead and viable populations, the shift of the viable cell populations every day (Figure C; shift of the populations day 1 red to day 2 green and day 3 blue to the left) indicates a change in metabolic activity: from a low ethanol concentration and aerobic conditions at the beginning the cells change into an anaerobic activity producing large amounts of ethanol after three days (Opitz et al., 2019).
Case study: Online Monitoring of Yeast Fermentation
Under the right sample conditions, measurements can be carried out in an online set-up: pumping the sample solution from the reactor directly through the flow cell where the measurement takes place and back into the reactor.
Samples were taken in a 10 min interval over more than 17 hours without dilution or addition of dyes or markers to the sample solution.
Time resolved online monitoring of cell concentration and viability of yeast in a fermentation process enables to monitor the conditions in the fermentation reactor. Figure 1 shows the comparison between cell concentration (grey line) and cell viability (blue line). Figure 2 shows the cell viability at the respective times as indicated also in Figure 1. It shows that after 11 hours only a very small viable population can be detected, even though the overall cell density indicates growth.
The monitoring of the fermentation process by Amphasys’ technology not only shows the lag phase and the early log phase but also uncovers the loss in viability of the yeast cells before entering in the log phase of exponential growth. The real-time monitoring allows to make adjustments of the fermentation conditions as needed.
Amphasys Cell Analyzer
The Ampha X30 is Amphasys’ next generation for cell analysis in Bioprocessing. It is tailor made for analyzing a broad range of different cell types like bacteria, mammalian, insect, algae or yeast. The newly designed technological platform enables highly accurate determination of, cell viability, concentration, differentiation, and cell status. This information must be considered in scale-up process during propagation in biofuel, bioplastic, enzyme, pharmaceutical or ethanol production.