Milk cool­ing cru­cial for ex­port dairy in­dus­try

DEMM Engineering & Manufacturing - - FOOD INDUSTRY - Con­tact: 07 348 6339 miguel@son­dex.co.nz

With stan­dards for milk and milk prod­ucts be­com­ing more strin­gent, busi­ness own­ers and farm­ers need qual­ity cool­ing op­tions to keep up the im­por­tant dairy in­dus­try’s con­tri­bu­tion to the Aus­tralian and New Zealand economies.

The dairy in­dus­try’s cus­tomers, for ex­am­ple those in the Asia/Pa­cific re­gion, are de­mand­ing 100 per cent as­sur­ance of the milk qual­ity from the mo­ment it leaves the cow to when the end-user pur­chases the prod­uct. That means strong con­trol over the qual­ity of the milk as it is be­ing taken from the cow, then onto the on-farm stor­age, pick-up and trans­porta­tion to the pro­cess­ing plant phases.

When milk is taken from the cow, its tem­per­a­ture is 35 de­grees. The longer it re­mains above 4’C, the greater the bac­te­rial growth and the more un­safe it be­comes to process. The tim­ing to cool the milk be­low 4’C is crit­i­cal to the qual­ity of the prod­uct, and af­ter a very short time it ac­tu­ally be­comes worth­less.

Ac­cord­ing to the Aus­tralian Depart­ment of Agri­cul­ture, Fish­eries and Forestry, milk must be cooled within two hours of milk­ing at no more than six to eight de­grees depend­ing on col­lec­tion date. The tem­per­a­ture con­trol sys­tem must main­tain the tem­per­a­tures to no more than 10 de­grees dur­ing trans­port.

This high­lights why the milk cool­ing sys­tem needs to be cor­rectly sized and se­lected in the first place and then checked and ser­viced at reg­u­lar in­ter­vals. One of the key com­po­nents of this is mak­ing sure the plate heat ex­changer can main­tain the heat load ef­fi­ciently and ef­fec­tively at the cor­rect tem­per­a­ture.

Milk cool­ers should be chill­ing the milk to within 2 de­grees of their cool­ing wa­ter sup­ply tem­per­a­ture or you are just throw­ing money into en­ergy bills. The cooler the milk en­ters the vat stor­age, the cheaper it is to keep cool and the bet­ter the qual­ity of the milk.

If the plate heat ex­changer isn’t work­ing prop­erly, ei­ther it is sized in­cor­rectly, or your herd has in­creased in num­bers and thus the cool­ing duty has changed, or sim­ply the milk cooler has be­come fouled with var­i­ous con­tam­i­nants that will cause a re­duc­tion in f low and/or in­ef­fi­cient cool­ing. The cool­ing sys­tem will then need to work much harder to cool the milk, again hurt­ing the farmer in en­ergy costs, and fi­nally the milk qual­ity will, not might, be com­pro­mised sim­ply from not be­ing chilled and stored cold enough.

Dairy farm­ers would be ad­vised to get a dual bank ex­changer that Son­dex can pro­vide. And re­mem­ber “the taller the plate the cooler the milk” - the old adage of just add more plates is long dead and gone, science clearly shows that the longer the ther­mal length of the heat trans­fer plate the longer the res­o­nance time in con­tact with milk, this is what will give you vir­tu­ally in­stant cool­ing of the milk to­gether with chill­ing it down to the re­quired stor­age tem­per­a­ture while re­duc­ing your en­ergy bills.

Son­dex can also as­sist in de­sign­ing and cre­at­ing spe­cific heat trans­fer equip­ment that can cover all the pro­ducer and pro­ces­sor’s milk cool­ing/heat­ing needs.

The penal­ties for non­com­pli­ance can be quite large for busi­nesses across re­gional Aus­tralia and New Zealand. If the milk is found to be not at the re­quired tem­per­a­ture or have high bac­te­ria counts, in­di­vid­u­als are ad­vised to cor­rect the fault. If af­ter this warn­ing the prob­lem is not fixed, there can be se­ri­ous con­se­quences - such as ex­clud­ing the pro­ducer’s milk prod­ucts from sup­ply and re­moval of dec­la­ra­tion of com­pli­ance.

This in­dus­try is full of fine mar­gins, which is why it is so im­por­tant to have your heat trans­fer sys­tem in top shape. If you are un­able to pin­point the faults in the heat ex­changer it may pay to con­tact Son­dex who can also of­fer pro­fes­sional tech­ni­cal ad­vice.

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