10 replies to this topic

[Esther]

Hello all

Anyone familiar to the UHT ( liquid ) milk industry, mainly regarding the sterilization test?

I would like to know your opinion about this test,I mean, what is it about?, what products should be carried out on?, at what point of the processing line should be carried out? and the most important question: frequency?

I will really appreciate your comments.

Thank you in advance

Regards
Esther

[Simon]

Can anyone help Esther with her query?

[Esther]

Hello all

Thank you Simon for your support.

Maybe that test I referred to above is called sterility test.

After making some queries I am starting thinking that that test do es exist or it is not used very often.

I am thinking in another region, besides mine, that is a big producer of milk: Holland.

I wish someone from there could make some comment.

Regards
Esther

[Cathy]

I am not sure what is meant by a sterility test. I would guess one checks for bacteria in the sample. I do recall there was a test for an enzyme...ACP was the abbreviation...I think the enzyme is acid phosphatase. The test can be used to determine if milk was pasteurized properly.

[hygienic]

hello esther:
regarding your inquiry about UHT milk.actully in the large dairy companies.milke sterilize in the UHT system at 144c for 5 second and after the sterilization process finished,milke must be packed in the bottols or cans ,any otherthing.
there is some chemical test post-packing for UHT milk for example, ph and acidity test to determine if the tempareture used of sterilization was high or not (burn test).and the other is catalyze enzym test .


monzer

[cazyncymru]

I've done Custard and dessert sauces in Combi / Tetra Pac, Pallecon and Bag in Box as UHT and we used to test sterility by plating out samples from a "zero Bottle"

the time / temp is important as is the sterilizing of the packaging( we used oxonia to sterilze packaging)

Sterilized milk in the UK means bottled milk going through a retort sterilizer, similar to canning. As far as i'm aware there is only one place left in UK doing sterilzed milk at that is Arla in Liverpool (i might be wrong)

C x

[AS NUR]

dear esther...

IMO... you can use methylene blue test... this test usually use for Raw material milk test...

[cbernard]

Here in the US it is pretty much standard practise to test for alkaline phosphatase in milk to confirm proper pasteurization. Raw milk has larger amounts of the enzyme , and it is almost completely inactivated by pasteurization.

Cheryl

They sell neat little kits in the US that are fairly easy to use, the components must be refrigerated. The test I am familiar with is provided through Charm Science and uses the Nova-Lum to read the results. It is a rapid test.

[cazyncymru]

Here in the US it is pretty much standard practise to test for alkaline phosphatase in milk to confirm proper pasteurization. Raw milk has larger amounts of the enzyme , and it is almost completely inactivated by pasteurization.

Cheryl

They sell neat little kits in the US that are fairly easy to use, the components must be refrigerated. The test I am familiar with is provided through Charm Science and uses the Nova-Lum to read the results. It is a rapid test.

We use either the A&M method or Flurophos to test phosphatase on milk (its a legal requirement in the UK). It can be used on UHT but it won't tell you if it's actually a UHT product, only a pasteurized product.

C x

[Esther]

Hello all

thank you very much for your answers but as Cazyncymry has pointed, my question is about UHT milk ann not about pasterized milk.

After some queries I think that this test I was told about, sterility test, refers to incubation of final product during X days at Y temperature and then check for spores. That could make sense.

On the other hand, if I am not mistaken, the peroxidasa test is done on UHT products.

The point of my question is frequency.

For example, does it make sense to do the incubation and spore check every hour in a liquid milk factory? Or , does it make sense to check for spores if after the incubation test the result is ok; I mean, no convex/distended packs?
I mean, If you are checking your raw material, assuming that your UHT process has been validated and it is controlled in a continuous way, and the aseptic conditions in the packaging process have been also validated, the equipment is calibrated and well maintained , does it make sense to carry out that test at that high (IMO) frequency?

REgards

Esther

[Esther]

Dear Cazyncymru

Thank you again for all yours comments on the sterility test isssue.

Your answer posted on 17th September is quite close to my question so I would like to ask you for the frequency of plating out samples whwn producing custard and desset sauces.

And one thing left, what do you mean by " zero bottle".

I want to thank you in advance

Regards
Esther