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By: me-trading

March 11, 2019

Increased Fat Content in the Discharge of you Clarifying Separator

Having a high-fat content in the discharge of your clarifying separator can be a real nuisance. Basically, this means that your clarifying process is inefficient. Good to know that usually there is one specific reason that is responsible for this error in your process. About this reason, I want to talk in this post.


Clarifying separators are basically used to remove, or to put it more precisely, separate non-milk-solids from the milk. Through this process an improved milk quality shall be reached. Separators of this kind are rarely found in countries of Western Europe, where high milk quality is often already assured at the farms. Clarifiers are commonly used in countries or regions where the quality of the milk that arrives at the processors is rather low.
It is clear that milk clarification is an important processing step. A study conducted by the University of Wisconsin reveals that there is an average of seven different types of hair in around 70 % of the cheeses and 40 % of the milk samples tested. Quite shocking if you ask me, especially if we consider that these test samples were taken from the U.S market, where milk quality is expected to be good.


Increased Fat Content in the Solids Discharge

When using a clarifying separator it is possible that you encounter abnormal fat content in the solids discharge. This usually has one specific reason: the bowl ejections are adjusted erroneous.
We have encountered cases where the problem of high fat content in the solids discharge is uncommonly high. And the main reason for this was that the concerned milk processors worked with total ejections for the discharge of non-milk-solids. Total ejections lead to the complete discharge of the separator bowl, while the feed is interrupted completely. This means that a considerable amount of milk is also discharged every time the clarifying separator executes a total ejection.
Through this approach you are losing milk, “clean” proteins and fat. Conversely that means that you literally lose money through this inefficiency because on the bottom line you are producing less product.
Total ejection ideally for chemical CIP of the clarifying separator, to guarantee best cleaning results.



Knowing that total ejection most probably is the reason for increased fat content in the solids discharge, the solution should be obvious: Adjusting the separator to execute partial ejections. Over the control cabinet you have to program the partial ejection intervals accordingly. In contrast to total ejection, the feed to the separator remains open while partial ejection is executed. Incoming solids load is discharged from the bowl. Complete discharge is avoided this way.
You have to experiment with different adjustments of the ejections of your separator and see what makes you achieve the best results in terms of efficiency. To test your clarification efficiency there are two commonly used methods:


  • Filter method
  • Somatic cell determination


With the filter method, around 500 ml of your clarified milk is put through a special cotton wool/fabric filter. The wool or fabric holds back any non-milk-solids still contained in the milk. Now the filter has to dry. Afterwards, it has to be examined in the laboratory and depending on the pattern visible, the milk quality can be evaluated.
The somatic cell determination is done by an automatic machine which does a cell count of somatic cells in the milk. The so-called somatic cell count (SCC) is the indicator of the quality of milk. The higher the SCC the lower the milk quality.


Best Practice

Unfortunately, it is hardly possible (as so often in life) to give the best practice advice regarding clarification or ejection intervals. Setting up a clarification process obviously depends on many individual factors, especially the quality of the milk that shall be clarified.


However there is one advise that I want to leave you with, without going too much into detail: To achieve the best result possible with your clarification process, I highly recommend to clarify your milk when it is warm, for example at 50 – 55 °C. Studies like the one from the University of Wisconsin mentioned above as well as studies conducted by GEA, show that this method achieves the optimum results. Below you can see a layout of an installation for warm clarification.


Clarifying your milk is a very important step in milk processing, especially in regions where milk quality is rather low. But using clarifying separators can lead to problems in terms of efficiency. One reason for lower efficiency can be an abnormal (high) fat content in the solids discharge after executing bowl ejection. In this case, you urgently have to move from total bowl ejection to adjustable partial ejections. Adjusted properly you can achieve a high grade of efficiency with your clarifying process again.


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