Why do we cool milk?

[Bald Rick]

Had a small group of farmers on a visit recently and sustainability came up.
One thing was milk cooling and the energy used to do that.
It does seem mad that we fret about dropping the temp below 5 degrees using a lot of plate water and power only for the dairy to immediately heat it up again on arrival to pasteurise it.

Seems especially mad when you're collected daily too

 

[Farmer Roy]

Well, here I’m guessing it’s because our summer daytime temps can be 40 + . . .

 

[vantage]

Had a small group of farmers on a visit recently and sustainability came up.
One thing was milk cooling and the energy used to do that.
It does seem mad that we fret about dropping the temp below 5 degrees using a lot of plate water and power only for the dairy to immediately heat it up again on arrival to pasteurise it.

Seems especially mad when you're collected daily too

A good few years ago I visited a farm in Southern Germany milking about a dozen cows, milk was piped to a small tank on the end of the byre, non refrigerated, locals called and drew off warm milk to use as they wished. In fact there was quite a demand.

 

[In the pit]

It’s so the dairy’s can store it in silos

 

[Tim G]

If you were to pasteurise it immediately then there would be little point. But milk comes out of a cow at a temperature ideal for bacterial growth and they grow very rapidly. Some bacteria would acidify the milk and the structure of the milk will change. Other bacteria will cause a safety issue and whilst standard pasteurisation kills most bacteria it won't kill everything, and it removes nothing.

 

[bigw]

Bacteria double in something like 20 minutes so i guess it wont be too appealing after a day or two! That said it does seem crazy to chill it then to heat it back up to pasteurise it.

 

[Bald Rick]

It’s so the dairy’s can store it in silos

Yes but leprino process all their milk into mozzarella almost as soon as it arrives. They also employ a sustainability wallah

 

[onesiedale]

beyond the bacterial side, the pasteurisation process then requires milk to be cooled afterwards.
The processing equipment is designed so that the cold milk coming into the plant cools the hot milk going out (Regen heat transfer), any raise in temp⁰, particularly above 5⁰ will mean that the pasteurisers Regen section will function sub optimally and lead to poor quality control and less plant efficiency.
Perfect temp for milk in silos is between 3⁰ and 4⁰.
No milk storage at dairies will have any form of cooling, just insulation.

 

[kiwi pom]

Yes but leprino process all their milk into mozzarella almost as soon as it arrives. They also employ a sustainability wallah

Even if they did, process it straight (they have no storage?) if you're on skip day pickup milking number one has been in the vat a long time.
Even every day pickup means a long time with warm milk.

 

[Bald Rick]

Even if they did, process it straight (they have no storage?) if you're on skip day pickup milking number one has been in the vat a long time.
Even every day pickup means a long time with warm milk.

Yes they have storage.

I am well aware of the bacto loading. Just seems a huge cost falls on the farmers shoulders as per usual

 

[frederick]

How much of our cooling energy is actually lost. Don't they use plate coolers to use our cold milk to cool the pasteurized milk back down again. Which heats the milk up closer to pasteurization temperatures.

Otherwise the dairies themselves would have an absolutely phenomenal cooling cost if they cooled all the pasteurized milk back down to processing temp or 4.5degrees in a liquid dairy.

 

[Clive]

Had a small group of farmers on a visit recently and sustainability came up.
One thing was milk cooling and the energy used to do that.
It does seem mad that we fret about dropping the temp below 5 degrees using a lot of plate water and power only for the dairy to immediately heat it up again on arrival to pasteurise it.

Seems especially mad when you're collected daily too

even madder - why do we dry grain to 15% ? it stores at 16% fine

how to reduced farmings C footprint ? ………….

 

[Bald Rick]

How much of our cooling energy is actually lost. Don't they use plate coolers to use our cold milk to cool the pasteurized milk back down again. Which heats the milk up closer to pasteurization temperatures.

Otherwise the dairies themselves would have an absolutely phenomenal cooling cost if they cooled all the pasteurized milk back down to processing temp or 4.5degrees in a liquid dairy.

TBH I'm not sure why they don't just irradiate the milk. Other than consumers might throw a wobbly, does radiation affect milk fats & proteins?

 

[Will Blackburn]

TBH I'm not sure why they don't just irradiate the milk. Other than consumers might throw a wobbly, does radiation affect milk fats & proteins?

Once irradiated or UHTed or even pasteurised the milk needs keeping aseptically to maintain freshness. Hence once opened UHT needs keeping in the fridge.

Separately, once milk and milk products leave the chiller cabinet it would reduce their premium position IMO.

 

[kiwi pom]

Yes they have storage.

I am well aware of the bacto loading. Just seems a huge cost falls on the farmers shoulders as per usual

Fresh milk needs to kept cold, how else can you do it?

Buyer could supply the vat and cooling equipment I suppose (Fonterra supplies all its vats I think, farmer owns the cooling) you still need to power it though.
Even if the buyer did it all they would then just pay you less to cover the cost.

 

[bobdav]

Surely there is scope to raise the milk temp limit above 5.0 depending on the timelines for getting it to the dairy. We used to sell to the local dairy ,and it would be in the pasturizer within an hour of leaving the farm. Our milk now goes to a broker with no depends where it ends up, so they are very fussy about it being below 5 degrees. My cooling the milk right down enables them to use lorries as cheap storage as they transport it around the country.
Would raising this limit to 6/7/8/9 degrees make that much difference to quality i don't know. Surely a good use of our levy money would be to find out. Every degree less cooling required would mount up to a substantial saving in money and energy usage surley.

 

[Farmer Roy]

even madder - why do we dry grain to 15% ? it stores at 16% fine

how to reduced farmings C footprint ? ………….

Our grain has to be 12.5% for export ( & also for domestic customers ) - consider yourselves lucky . . .

PS - 14% is about the limit here at which we can store grain without aeration

it soon heats up & goes mouldy otherwise

 

[onesiedale]

Would raising this limit to 6/7/8/9 degrees make that much difference to quality

definitely yes.

 

[upnortheast]

Every summer we get a couple of phone calls, something wrong with your milk, it`s gone off before the date on the bottle.
Whenever possible, we jump in the car with our calibrated thermometer.
95% of the time we find a fridge running over 8 degrees. No one has a clue what temp their fridge runs at. - "well the light is on"

Our all time favourite response, - " but we put it back in the fridge every night "

So I think getting the milk down under 5 degrees then throughout the supply claim is essential to get a good product to the customer

 

[Tim G]

Would raising this limit to 6/7/8/9 degrees make that much difference to quality i don't know. Surely a good use of our levy money would be to find out. Every degree less cooling required would mount up to a substantial saving in money and energy usage surley.

Listeria monocytogenes will survive and grow even at refrigeration temps (below 5°c), albeit slowly. The warmer the milk, the quicker it will grow and that will drastically reduce shelf life.