Propionic acid bacteria (Bact. propionic acids)

Propionic acid bacteria produce propionic acid from lactic sugar and calcium lactates, acetic acid and carbonic acid anhydride. They develop within temperature limits 15 do 40°C, the optimum is around 36 ° C. Initially, especially in milk, develop very slowly, while strongly in cheeses, in which they find convenient conditions. They produce normal eyes in Emmental and other cheeses in their later maturation period. They are always in the milk, because they get into it with the faeces. They are most easily found in piglets' faeces. There are many varieties of these bacteria. Spherical varieties are used in cheese making as pure cultures and only in exceptional cases, when the cheeses are not prone to meshing. The cheese maker gives little of them, bo 1 do 3 drops of culture on 1000 kg of milk, go straight to the boiler, or to the maturing rennet mortar. Larger amounts of these cultures make it excessive, or the uneven holes in the cheeses. Dosing in small amounts is warranted, considering, that in one drop of culture there are approx 500 000 bacteria, which they will have 5 do 6 weeks to multiply in the cheese to an enormous number, i.e.. when the time is right for their activity.
Propionic acid bacteria are sensitive to table salt. That is why cheeses are saltier more strongly right from the beginning of ripening, when aimed to prevent mesh formation, e.g. in grating cheeses, which should be "blind”.