Under refrigerated conditions, gram-negative bacilli that can
produce under such conditions (psychrotrophic/cold-loving)
bacteria) tend to predominate, especially Pseudomonas spp.

This is especially so when the milk has a high initial infection
of these bacteria and the milk is stored for 2-4 days before
pasteurization, which is often the case these days, where milk
it is mostly collected from farms every other day only.

This deterioration also tends to influence the final products produced.
of such milk, because although most of the bacteria will be killed
by pasteurization, some produce exo-enzymes that survive
pasteurization and even UHT (Ultra High Temperature/Long
life) process in some cases.

An example of Pseudomonas attacking dairy products happens a lot
with cottage cheese Pseudomonas are widely distributed and
aerobics. They tend not to need a lot of carbohydrates, which helps
much in attacking the cottage cheese, because most of the
the lactose has been removed in the cheese making process. They live
very well in high-protein foods such as cottage cheese that produces
slime, pigments and odors. They also prefer high water activity.
(high humidity), which makes cottage cheese more or less the
Ideal meal considering all that has been said.

Many Pseudomonas spp. are psychrotrophic (cold lovers)
bacteria although they will grow much faster from 15 degrees
Celsius at temp.

Thus, a temperature shock during transport, for example, will give
them a big push – to cause even more destruction.