The curd grains are collected under whey, avoiding mixing with air; lightly pressed and cut in pieces, one for each cheese; placed in molds and finally pressed for 1 to 2 hr or more. The molds are equipped with cloths or perforated for drainage of whey and for formation of a closed rind on the cheese. This method results in a closed texture with only microscopic bubbles of air. The closed texture is an important factor for obtaining the wanted structure of round-eyed cheeses. The starter cultures used for semihard round-eyed cheeses (e.g., Gouda/Danbo) contain bacteria that in 1 to 2 weeks can ferment the citric acid, thereby producing CO2.
Initially CO2 is dissolved in the cheese, but eventually the combined pressure of CO2 and that of the N2 dissolved in the cheese begins to expand the largest of the microscopic air bubbles. If the velocity of the formation of CO2 is suitable, the gas will expand only a few of the largest air bubbles because of the following physical law:
Pressure in a bubble = surface tension/radius of the bubble which states that less gas pressure is required for enlarging a large hole than a small one (11). The same applies for large-eyed cheeses (e.g., Emmental and Jarlsberg), where the eyes are expanded by CO2 produced by propionic acid bacteria by fermentation of lactic acid.
Was this article helpful?