Beer Foam

The main chemical components of beer foam are healthy protein breakdown, glucose polymers and isohumulones, and the healthy protein factor is the most critical. Beer foam is one of the signs that distinguish it from various beverages, and it is also a crucial quality indicator. High-quality beer has white and delicate bubbles, uniform color, and strong milky aroma, which is pleasant and exciting. It has the reputation of "liquid bread". Four factors for beer foam performance: appearance, foaming power, persistence, and adhesion.

Composition of beer foam

• Protein: It is one of the main products of beer foam, and nitrogen-containing substances are the basic materials for the development of foam. These healthy proteins create a sticky, impermeable and versatile protein bubble film.

• Polypeptides: Polypeptides affect foam in a glycoprotein manner, they have surface-active effects, increase the thickness of the bubbles and reduce the rate at which vacancies fall into the liquid. The sugars in the glycoprotein protect the peptides from precipitation loss throughout the brewing process. The higher the hydrophobicity of the polypeptide, the more stable the development of the foam, and the higher the hydrophobicity of the polypeptide particles in the same variety, the better the safety of the foam.

• Isohumulones: It is formed when the hops in the wort are isomerized and can enhance the foam in the cup. In fact, the cost of isohumulones is particularly low, and can be combined with ionic bonds through peptides, and the resulting complex is the main body of the beer foam.

• CO2: Beer foam itself is composed of protein-containing CO2 gas and various other colloidal substances produced during the diffusion process. Refined bubbles give the beer its specific body, softness and brittleness, enhancing spread and mouthfeel. The carbon dioxide material affects not only the surface area gas release, but also the size of the foam as well as the thickness of the foam. Foam sizes of 0.2 mm are generally considered ideal.

Factors in the formation of beer foam

• Surface activity: Active substances such as protein and hop resin reduce the surface tension of beer and promote the development of bubbles. As well as forming an adaptable safety layer between the air bubbles to avoid the accumulation of air bubbles, it is beneficial to its durability.

• Metal ions: Nickel and various other steel ions in beer can directly combine with alpha-acids to form insoluble substances, thereby improving the safety and binding force of foam.

• Alcohol: Alcohol dissolves many water-soluble substances as well as liquefied compounds of non-polar solvents. If combined with CO2, peptides, etc., it will destroy the surface tension. A moderate amount of alcohol is beneficial to increase the surface viscosity of beer.

• Beer Consistency: Protein and high-consistency gluten products can easily form a high-toughness film edge, ensuring that the formation of bubbles is not easy to disappear, making the bubbles lasting.

• Temperature and pH: When the temperature and pH are lowered, the foam is more elastic.