Cooling requirements and methods of raw milk
冷却要求 I. Cooling requirements
10 ℃ 以下，可抑制微生物的繁殖；若降至 2~3 ℃ 时，微生物几乎不繁殖；不马上加工的原料乳应降至 5 ℃ 以下贮藏。 The freshly squeezed milk immediately drops below 10 ℃ , which can inhibit the proliferation of microorganisms; if it drops to 2 ~ 3 ℃ , the microorganisms hardly multiply;
冷却的方法 Second, the cooling method
1 ) Pool cooling
3~4 ℃。 The most common and simple method is to cool the milk tank filled with ice or cold water in the pool, which can cool the milk temperature to 3 ~ 4 ° C higher than the cooling water temperature . In order to accelerate cooling, frequent stirring is required, and drainage and water replacement are performed according to the water temperature. The amount of water in the pool should be 4 times the amount of cooling milk. The pool should be thoroughly washed every 3 days, and then washed once with a lime solution. The disadvantages of pool cooling are slow cooling, high water consumption, high labor intensity, and difficult management.
浸没式冷却器冷却 2) Cooling by immersion cooler
This cooler is lightweight and can be inserted into a milk tank or milk tank to cool the milk. The submerged cooler is equipped with a centrifugal agitator, which can adjust the stirring speed, and has an automatic control switch, which can automatically stir at regular intervals, so that the milk can be cooled uniformly and the cream can be prevented from floating. Scale ranch.
冷排冷却 3) Cold exhaust cooling
The cold row consists of metal row tubes. Milk flows from the pores at the bottom of the upper distribution tank to form a thin layer. It flows through the surface of the cooler and flows into the milk storage tank. Canals to reduce the temperature of milk flowing down the cooler surface. This cooler is suitable for small-scale processing plants and dairy farms
片式预冷法 4) Sheet pre-cooling method
Generally, medium- and large-scale dairy plants use slice precoolers to cool fresh milk. The sheet precooler has a small footprint, and the cooling effect is sometimes not ideal. 4～８℃水），则可使鲜乳降至６～10℃，效果极为理想。 If the groundwater is directly used as the cold source ( 4-8 ° C water), the fresh milk can be reduced to 6-10 ° C, and the effect is very ideal. When general 15 ℃ tap water is used as a cooling source, it is necessary to cooperate with the use of an immersion cooler to further reduce the temperature.