Raw milk contains a multitude of microorganisms. The vast majority do not survive pasteurization, but some do – including spores that are capable of triggering new bacterial growth.
Unwanted bacterial growth can cause problems during cheese maturation especially. In particular, two types of clostridia can degrade cheese quality.
Clostridium butyricum and Clostridium tyrobutyricum originate in soil and may end up in silage used for cattle feed. Rainy weather during silage production can increase the concentration of soil-based clostridium spores, resulting in a higher load in raw milk.
Clostridial spores that enter the cheese making process can produce hydrogen gas, inducing cracks, inflating the cheese and causing off-flavours.
Different methods can be deployed to limit the number of spores in cheese. One is to use a Bactofuge unit – a type of separator that removes microbes using centrifugal force.
A Bactofuge unit effectively reduces clostridial spore presence in milk and is a common component in lines for pre-treatment of cheese milk and the production of consumption milk, as well as for milk and whey intended for powder.
“The absence of air minimizes the risk of particle and aggregate size being reduced, enabling better spore and bacteria removal efficiency,” says Ulrika Rehn, dairy centrifuges specialist at Tetra Pak.
In contrast to competing models, Tetra Pak Bactofuge units treat the product very gently. The product enters the Bactofuge bowl smoothly and accelerates gradually as it passes through a hollow rotating spindle.
Air entering the process at this point could fracture the fat globules in the product and cause product foaming downstream. Tetra Pak Bactofuge units prevent such problems from ever arising.