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Fermentation processes are used in many industries to produce a variety of products, ranging from beer and wine to dairy products, biofuels and even medicines. During fermentation, micro-organisms, such as yeast and bacteria, break down sugars and other components to produce end products such as alcohol, organic acids and gases. One of the most common gas emissions during fermentation is carbon dioxide (CO2) and ethanol (C2H6O).
The concentrations of CO2 and ethanol in fermentation processes vary depending on several factors, such as the type of micro-organisms involved in the fermentation, the fermentation conditions (temperature, pH, etc.), the amount of substrate used and the duration of the fermentation. In general, during fermentation, the concentration of CO2 increases gradually as the micro-organisms metabolize the substrates and produce CO2 as a by-product. Depending on the type of fermentation, the concentration of CO2, as well as ethanol, can vary from a few percent to several tens of percent in some cases. The monitoring of these two gases is therefore essential.
During the fermentation process, some gases are emitted and it is important to measure their concentration. In general, it is carbon dioxide that is most commonly produced during fermentations as well as ethanol.
Measuring CO2 can provide important information about the progress of fermentation and the conditions under which the micro-organisms perform the fermentation process. If the amount of CO2 produced is low or irregular, it may indicate that the micro-organisms are not growing properly or that the fermentation conditions are not optimal. On the other hand, regular CO2 production may indicate that the micro-organisms are fermenting efficiently and that the conditions are favorable.
Measuring the concentration of gases emitted during fermentation is crucial, with carbon dioxide and ethanol being the most commonly produced gases. Several types of sensors can be integrated into fermentation processes to monitor and control these gas emissions.
Non-Dispersive Infrared gas sensors work best for gas analysis in fermentation processes because they are highly selective and accurate for measuring the concentration of specific gases, such as carbon dioxide (CO2), and ethanol (C2H6O), which are important indicators of the fermentation process.
In NDIR gas sensors, a sample of the gas is passed through an optical filter that absorbs specific wavelengths of infrared light. The amount of light absorbed by the filter is proportional to the concentration of the gas being measured. This allows the sensor to provide highly accurate and reliable measurements of gas concentration.
Other kinds of sensors are also able to detect CO2 and ethanol : electrochemical and semiconductor gas sensors.
Electrochemical sensors use an electrochemical reaction to detect and measure the concentration of gases. Semiconductor sensors detect and measure the concentration of gases by measuring the change in electrical conductivity of a semiconductor material when exposed to the gas. Although they have cost advantages, they also have some disadvantages including limited lifetime (2 to 3 years), cross-sensitivity with other gases, temperature and humidity dependance, calibration requirements, limited gas range and toxic chemicals. Despite being slightly more expensive to purchase, NDIR sensors have many advantages over other types of sensors. They have a longer lifespan, are less fragile, and offer greater accuracy. This makes them more cost-effective in the long run, making them ideal for users looking for a high-quality product.
Poor control of CO2 and ethanol emissions during fermentation can lead to several risks, including:
Therefore, it is crucial to monitor and control the concentration of CO2 and ethanol during fermentation to prevent any safety hazards and ensure high-quality products. The monitoring and control measures may vary depending on the type of fermentation process, but can include using sensors and monitoring devices, regulating temperature, ventilation, and proper handling and storage of fermentation vessels.