Foam Control in Fermentation

Managing conditions that cause air entrainment or foam formation is vital to agribusinesses and food processors. Air entrainment and foam formation can be caused by impurities, cell lysis, gas formation, chemical reactions, agitation or mixing, and high pressure; this can harm the product by creating high levels of organic compounds, proteins, and starches, which generate foam. Applied Material Solutions (AMS) provides products and solutions to prevent foam and air entrainment in food processing and agribusiness facilities. Our products include:

• Polyether-based defoamers
• Non-silicone antifoams
• Water-based defoamers
• Silicone antifoams
• Powdered antifoams

We will explore why foam control is essential in fermentation processes, how you can control foam formation during fermentation, and the types of defoamers and antifoam products available to address your fermentation needs.

The Importance of Foam Control in Fermentation

Minimizing foam is critical to fermentation processes, especially those that are highly loaded and large in scale. Excessive foam can wet the filters or contaminate the product. Some of the product can also be siphoned from the fermenter as foam builds. The primary problems with foaming are overflow, inefficiency, and potentially dangerous use of the reactor.

Foaming often results from proteins and/or starches stabilizing liquid foam films. Some foam reduction methods may result in a reduction of mass transfer, so the methods used should be carefully evaluated.

How to Control Foaming in Fermentation

During the fermentation process, foam can be controlled through the addition of a chemical antifoam or defoamer. To prevent foam from forming in the first place, chemical antifoams are introduced to the broth before fermentation, which reduces the need to dose the broth during the fermentation process. Continuous foam control may be necessary for some fermentations, in which case a defoamer is intermittently applied as foam forms. Chemical defoamers also prevent foam formation during sterilization and cooling processes.

In applications where foaming should be avoided completely, chemical antifoams are recommended. This is especially important because the foam may contain substances that react with increased oxygen levels.

Mechanical defoaming is an alternative to chemical defoaming. The most effective mechanical defoamers have rotating elements to knock down generated foam. There are also mechanical solutions that remove and recycle foam using jets or suction by forcing air onto the surface of the foam. Generally, a mechanical foam control solution is typically more expensive and can be more complicated to maintain than chemical foam control.

Types of Defoamers for Fermentation

The primary defoamers used in fermentation are silicone and polyether defoamers. While both types of chemical defoamers are used in fermentation, they offer different characteristics.

Polyether-Based Defoamers

Containing oxygen, carbon, and hydrogen elements, polyether-based defoamers are created from polymerization reactions between propylene oxide and/or ethylene oxide under pressure. Added during fermentation, polyether-based defoamers act quickly and offer long-term, effective antifoam performance. The product continues to perform after high-temperature sterilization processes, and when properly selected should have no effect on the fermentation broth, microorganisms or the final product.

Silicone Antifoams

Silicone antifoams are typically made of dimethyl silicone oil, hydrophobic silica, water, thickener, and emulsifiers. They mostly contain the elements carbon, silicon, oxygen, and hydrogen. At normal temperatures, silicone antifoams offer fast foam knock down and good foam suppression. Silicone antifoams are often an economical option but may or may not offer the same level of performance as polyether-based defoamers.

When using silicone antifoams in fermentation, it is vital to evaluate the antifoam before using it in production. Silicone antifoams contain silicone and silica, which may foul the filtration membranes or processing equipment and remain in the fermented product after use.

Fermentation Defoamers From Applied Material Solutions

Foam control is critical to fermentation, preventing system damage and product contamination. As a provider of food-grade fermentation antifoams and defoamers, Applied Material Solutions is poised to assist with your foam control needs. Please see our foam control solutions webpage for more information. Contact us to speak with a member of our team about our foam control solutions for food processing and agribusinesses.