The cream separator is a dairy machine used to separate
fresh whole milk into cream and skim milk. Formerly the separation
was made by gravity method, allowing the cream to rise to
the top of a pan and then skimming it off. C.G.de Laval of
Sweden devised the first mechanical cream separator in 1880,
based on the principle of centrifugal force.
How it works: Whole milk is conducted into
a bowl, commonly through a central tubular shaft. A spindle
rotates the bowl at a rate of from 6,000 to 9,000 rpm, and
a series of identical conical disks separates the milk into
vertical layers. The heavier skim milk collects on the outer
circumference of the rapidly whirling bowl, and the lighter
cream tends to remain in the center. The pressure of the incoming
whole-milk supply then forces the cream and skim milk out
of the machine and into separate collecting vessels. The cream
separator makes it possible to control the amount of fat (Called
Butterfat) remaining in the milk. The gravity method ordinarily
leaves one fourth of the fat in the milk, while the cream
separator leaves only 0.01% to 0.02% of the fat in the skim
milk. Since the latter process is much faster than the gravity
method, there is less chance for harmful bacterial action.
1899 Auguste Gaulin obtained a patent on his homogenizer.
The patent consisted of a 3 piston pump in which product was
forced through one or more hair like tubes under pressure.
It was discovered that the size of the fat globules produced
were 500 to 600 times smaller than the tubes There have been
over 100 patents since, all designed to produce smaller average
particle size with expenditure of as little energy as possible.
The homogenizer consists of a 3 cylinder positive piston pump
(operates similar to a car engine) and homogenizing valve.
The Pump is turned by an electric motor through connecting
rods and crankshaft.
How it works: If raw milk were left to stand,
the fat would rise and form a cream layer. Homogenation is
a mechanical treatment to the fat globules in milk brought
about by passing milk under high pressure through a tiny orifice.
This results in a decrease in the average diameter and an
increase in number and surface area. The net result is a much
reduced tendency for creaming of fat globules. To understand
the mechanism, consider a conventional homogenizing valve
processing milk at 2500 psi. As it first enters the valve,
liquid velocity is about 4 to 6 meters/second. It then moves
into the gap between the valve and the valve seat and its
velocity is increased to 120 meter/sec in about 0.2 milliseconds.
The liquid then moves across the face of the valve seat and
exits in about 50 microseconds. The whole process occurs between
2 pieces of stainless steel in a stainless steel valve assembly.
process of pasteurization was created by Louis Pasteur. Pasteurís
aim was to destroy bacteria, molds, spores, etc. He discovered
that the destruction of bacteria can be performed by exposing
them to certain minimum temperature for certain minimum time
and the higher the temperature the shorter the exposure time
How it works: How it works: There are three
forms of pasteurization..... Batch or Vat, HTSTand UHT pasteurization.
1. Batch or Vat pasteurization was the first form of pasteurization
used. It heats the product up to 145 F for 30 minutes.
2. The second is HTST, high temperature, short time pasteurization.
As stated in the name, it is a shorter process with higher
temperatures. The required temperature is typically 161 F
to pasteurize the milk. This is a continuous method and a
"hold tube" is used to transport the milk after
it has been heated. The "hold tube" is sized so
that it takes 15 - 20 seconds for the product to travel all
the way through it. Once the product reaches the end of the
tube, if the temperature is at 161F, it is then considered
3. The third is UHT, ultra-high temperature pasteurization.
This method is used mostly for coffee creamers and boxed juices
in the US. The product is brought to 250F (under pressure)
for only a fraction of a second.