Homogenizer breaks the fat globules. Large size fat globules have tendency to float and form a cream line on the surface making milk a non-homogenous product.After homogenization the milk globules number increases 10,000 times and the size is reduced 1/10 th of the original, usually less than 1 mm size and hence the tendency of rise of fat globule is considerably reduced. This equipment is also employed for preparing reconstituted milk, ice-cream mix, etc. The main reason is to make a homogenous product.
From technological angle, there are tremendous improvements in the quality of milk and ice cream. In this equipment (Figure-2.9) the milk is passed through a small opening under very high pressure. This generates the velocities of the order 100 to 250 m/s, resulting in high shear stresses. These shear stresses break up the fat globules.
i. Homogenizer
The are various types of homogenizer, based on the type of homogenizing head.Also the operation could be in single stage or in two stages.Two-stage operation is considered most efficient because the sheared globules have little chance of getting mixed again. They remain dispersed. In general the homogenizer consumes very high electrical energy. The initial cost of machine is also high, as the material of construction requires special material, which is very hard and hence, expensive. A homogenizer comprises of a homogenizing head,homogenizer triplex pump, high capacity motor, power transmission mechanism, and a pressure gauge.
ii. Centrifuges
Fresh raw milk contains fat 4.5% or above. It also gets contaminated with dirt,straw, etc., even leucocytes (udder cells) gets into the milk during milking. Both of these could be removed by centrifugation process.
Cream separator: It is equipment, which operates continuously and imparts centrifugal force to the incoming milk stream.
Clarifier: It is similar to the cream separator. Its function is to remove extraneous elements such as dirt, chaff and leucocytes cells, etc. These are heavier and the undesirable elements. By centrifugation these particles are collected at the periphery.There is enough space (residue space) provided in the bowl, which accumulates these particles until the unit is stopped and cleaned. In case the residue level is high or the operation is required for longer duration the residue needs continuous removal.Therefore, modern separators have been provided with clarifiers to remove sludge in continuous manner.
From technological angle, there are tremendous improvements in the quality of milk and ice cream. In this equipment (Figure-2.9) the milk is passed through a small opening under very high pressure. This generates the velocities of the order 100 to 250 m/s, resulting in high shear stresses. These shear stresses break up the fat globules.
i. Homogenizer
The are various types of homogenizer, based on the type of homogenizing head.Also the operation could be in single stage or in two stages.Two-stage operation is considered most efficient because the sheared globules have little chance of getting mixed again. They remain dispersed. In general the homogenizer consumes very high electrical energy. The initial cost of machine is also high, as the material of construction requires special material, which is very hard and hence, expensive. A homogenizer comprises of a homogenizing head,homogenizer triplex pump, high capacity motor, power transmission mechanism, and a pressure gauge.
ii. Centrifuges
Fresh raw milk contains fat 4.5% or above. It also gets contaminated with dirt,straw, etc., even leucocytes (udder cells) gets into the milk during milking. Both of these could be removed by centrifugation process.
Cream separator: It is equipment, which operates continuously and imparts centrifugal force to the incoming milk stream.
Clarifier: It is similar to the cream separator. Its function is to remove extraneous elements such as dirt, chaff and leucocytes cells, etc. These are heavier and the undesirable elements. By centrifugation these particles are collected at the periphery.There is enough space (residue space) provided in the bowl, which accumulates these particles until the unit is stopped and cleaned. In case the residue level is high or the operation is required for longer duration the residue needs continuous removal.Therefore, modern separators have been provided with clarifiers to remove sludge in continuous manner.
Cream separator and the clarifier could also be an integrated unit. The modern centrifuge has provision to remove cream or adjust the amount of fat required and also to remove dirt.
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