Foam generated during the beer fermentation process can be divided into two categories. The first type of foam exists in the fermentation liquid; this foam is highly viscous, easily forms bubbles, and contains substances such as proteins and metabolic microorganisms. The second type of foam is caused by CO2 produced by microbial respiration; it is fine, stable, and difficult to eliminate. So, what kind of defoamer should be used for beer fermentation?
Defoamers can be divided into three categories: defoaming agents, foam inhibitors, and deaerating agents. In addition, they can be classified by their composition into natural oil-based defoamers, silicone-based defoamers, higher alcohol-based defoamers, polyether-based defoamers, and polyether-modified silicone oil-based defoamers. Different types of defoamers have different characteristics and application ranges, and should be selected according to the specific situation.
Natural oil-based defoamers.
Oils can not only inhibit foam formation but also provide nutrients for mycelia. Natural oils have lipophilicity and high viscosity, and their surface tension differs from that of the fermentation liquid, thus inhibiting foam formation to some extent. At the same time, oils, as a natural carbon source, can provide nutrients for the growth and metabolism of mycelia, which is beneficial to the development of mycelia. However, the defoaming ability of oils is limited, and prolonged use can lead to rancidity and oxidative deterioration. Therefore, when using oils, pay attention to using them in appropriate amounts and replacing them promptly.
Silicone-based defoamers.
Polydialkylsiloxane defoamers have poor solubility and are difficult to disperse in water, resulting in poor defoaming and foam inhibition effects when used alone. However, we can disperse the silicone powder particles in a mixture with oil before use to improve its surface activity, stability, hydrophilicity, and dispersibility, thereby effectively enhancing its defoaming and foam inhibition effects. It is worth mentioning that this defoamer does not react with substances in the fermentation liquid system, does not affect product quality, has a long-lasting foam inhibition time, and is physically and chemically stable.
Higher alcohol-based defoamers.
Higher alcohol-based defoamers? This polymer has strong permeability, is easy to disperse, is resistant to high temperatures and alkalis, and is highly efficient in small amounts. It is widely used in chemical, pharmaceutical, food, and other fields. It mainly refers to polymers of fatty alcohols, polyethers, hydrocarbons, amides, etc. It has strong penetration ability, effectively reducing surface tension and viscosity, thus achieving defoaming effects; it is easily dispersed, uniformly distributing in water and oil, thereby improving product stability; in addition, it has characteristics such as high temperature and alkali resistance, allowing it to be used in different environments with a small dosage and good results.
Polyether defoamers.
Polyether defoamers are non-ionic surfactants with fast spreading speed and high stability. They can effectively inhibit and eliminate foam, and have low toxicity, making them widely used in detergents, dyes, inks, and other industries.
Polyether-modified silicone oil defoamers.
Polyether-modified silicone oil defoamers are high-efficiency defoamers obtained through polyether grafting and block modification. They combine the advantages of both silicone oil and polyether defoamers, having lower surface tension and higher dispersibility, effectively inhibiting and eliminating foam. They are not only widely used in the detergent industry but also have important applications in food, medicine, cosmetics, and other fields.
