Microbial fermentation involves using microorganisms to convert raw materials into other products under certain conditions. Microbial fermentation requires cultivation on the surface of a liquid. The culture medium contains protein-based surfactants, which, when aerated, can easily produce foam. Foaming can lead to many negative factors, such as a reduced filling factor of the fermenter. Severe foaming can also cause the fermented liquid to overflow from the exhaust pipe or shaft seal, significantly increasing the risk of contamination. Therefore, a microbial fermentation defoamer is necessary to reduce foaming. Let's discuss how to use a microbial fermentation defoamer.
Causes of Foaming in Microbial Fermentation:
The causes of foaming in microbial fermentation can generally be categorized as follows.
Excessive microbial activity in the culture medium and excessively rich raw materials in the culture medium can lead to a high organic nitrogen content.
Temperature increases combined with excessive stirring can also cause excessive foaming.
The microbial environment surrounding the culture medium, such as composition, aeration rate, and rotational speed, can also contribute to the formation of foam.
Although a moderate amount of foam during microbial fermentation can aid in the fermentation process, excessive foaming can have many negative effects:
Fermentation liquid can leak from the exhaust pipe or shaft seal, increasing the chance of contamination by other bacteria.
Excessive foaming can also cause liquid escape and product loss. The presence of foam can also reduce the fermentation tank's filling factor.
Due to the fluctuation in foam levels, microorganisms in different growth cycles can float with the foam or adhere to the tank walls, causing these microorganisms to grow in the gas phase, affecting colony uniformity.
When using a defoamer for microbial fermentation, initially add a small amount of defoamer to a separate fermenter and observe the defoaming time and speed. Avoid adding too much defoamer; defoamers eliminate foam by changing the surface tension of the liquid. If too much is added, the effect will not be normal, and if too little is added, the defoaming requirements cannot be met. The recommended dosage is 1/1000 to 3/1000. The specific dosage should be determined after experimental testing.
