Hi Hossem,

you should add preservatives such as 0.02% bronopol (2-bromo-2-nitro-1, 3 propanediol) OR 0.03% Sodium azide (NaN3) to your milk samples and keep them refrigerated until analysis (a polystyrene box with some ice packs can be ok).

Bronopol can be prepared as a 10% solution and stored at Room Temperature, then you just add 2 ml of this solution in one liter on milk. Sodium azide is available as tablets you add to your milk samples without dilution.

Hope this helps.

I'm very grateful for your help Leonardo. in my situation, I don't have bronopol or sodium azide now, so, I would know if freezing doesn't alter milk composition (fat and protein content). thank you

if your transportation time is 3hours or less you have to refrigerate the milk to 4 Celsius, if it will be more than three hours you may add hydrogen peroxide 250 ppm in addition to the refrigeration.  

thank you Ebrahim. so I understand that freezing alter milk composition, didn't it?

freezing effect is not too much important in most cases, but you have to read the catalog of the machine very carefully first. 

Hello d-r Hossem

My suggestion is to use one thermally insulated wooden box with ice and put the sample bottles or vials (we are using according to Chalmers) and nothing more, no money spending :)

For chemical examination of milk,  this sample conservation during transport is correct but for microbiological analyzes not.

Best

Vesna

thank you very much Vesna, but I think that chemical composition is related to microbiological composition! in fact, microbes could generate lipolysis and proteolysis phenomenons and so, modify chemical composition! this problem shouldn't be when analysis is done the same day of sample, but when I have to analyse samples the day after, I think I should freeze samples. what do you think?   

If you IMMEDIATELY cool your sample to 4 °C and keep them refrigerated, very few bacteria can develop in your milk, so it should be safe to perform the milkoscan analysis the following day. In this case you can have reliable somatic cells count, even though they may be slightly overestimated.

If you need longer storage (for example, the weekend), then you should freeze them.

If I am not wrong, some experiences have been made by ACTILAIT, a French Technical Institute for dairy (now ACTALIA) and they saw that the milkoscan spectra of samples were not significantly affected by freezing. The trick is, if I remember well, to cool them as soon as possible and freeze them, and to thaw them by placing them directly in a 37 °C waterbath, immediately before analysis.

It goes without saying:

- collect the minimum volume needed for the analysis (30 ml?) the smaller the volume the more rapidly and evenly you'll cool/heat the sample;

- use tubes that can resist freezing and thawing and don't fill them completely otherwise they can break and leak; Use a marker or some id that can resist the freeze/waterbath routine.

- don't ever shake or vortex the sample but rather GENTLY mix milk by inverting the tubes, to preserve milk fat globules integrity;

- the Somatic Cells value will probably be inconsistent after freezing because cells will have exploded. 

I can check with my colleagues for more precise information, but I think that will do.

I also suggest that you make your own tests in your own field conditions, for instance collecting (let's say 10) samples at day 0 and analysing duplicate aliquots at day 0, 1 and 3 after storage at +20, +4 and -18 °C. This should tell you which is the protocol that best suits your situation on the field.

Thank you very much Leonardo, I think your answer is complete, I'm very grateful!

d-r Hossem!

I saw very nice explanation from prof Bianchi, it is your best solution to find the suitable protocol for you, and field conditions....also I made examination wit cooled and frozen milk samples and I found higher average value  of total viable count (cfu/ml) at frozen samples, and also lower average value of Enterobacteriaceae sp. in frozen samples in comparition with cooled samples....but I do not know nothing for your aim, if this milk will be processed in yoghurt or cheese, or ? Mine research was for milk quality at farms with HACCP protocols and not ....if you need something do not hesitate to write me, I m glad that I saw nice coments from other reasearchers and also good luck in your work :)

Vesna

Well, thank you Vesna, but I'm not a professor, so in the future you can call me Leonardo and that will be just fine!

thank you Vesna, I'll tell you more about my work, I want to record milk production of goats to proceed to genetic selection, and to do that, I need to know milk composition (fat and protein) of each goat, that's why I'm looking for a reliable preservation method during transportation.

Well, Leonardo, exuse me, I m deeply sorry if I said something wrong, I just saw nice and aplicable answer by your side so I wrote professor :)

Really, I m wishing you nice research work in future

Vesna

Hossem

You are doing nice work, here we are doing examination with goats milk and goat dairy products, but as we dont have Institut for Animal genetic and selection this field is not so much in progress, but if I can help you something just write me

Best

Vesna

Dear Vesna,

thank you for responding! indeed, goat genetics is a good field. I'm very grateful, you too, if you need anything, I'll be pleased you contact me.

Simply you should  keep chill condition till you take to Lab. for that you can use the ice box with some ice pack. I suppose to keep chill condition rather freezing when i do testing. 

other than chilling you can use dicromate to preserve milk samples without spoilage.

You can cool your samples to 3 - 5 ºC, transport it in a ice box and You should do your analysis as soon as possible. Or you can make Your analysis direct at the farm with a transportable milkoscan 

Hi  again Hossem, you can use also some milk conservative as bronopol that can help to keep in good form sample at room temperature during transportation (i.e. in a fridge or cold box it is always better!). It is a classical way to do here in some country. To evaluate degradation and impact on milk quality, You can make also a standard curve between fat/protein or lactose content during time and at different temperature. That can help to correct data.

best regards

Many times, I collected milk samples from dairy farms that were about 2-3 hr away from our lab. According to my experience, keeping milk samples in the ice box will not effect the quality parameters of milk.

Ecomic East tipo Ice Box mantain  temo verter and zafe Plus bronopll

Aditional to have in mind.milkoscan protocol inform about milk temp previous to the anslysis so mantain te sample chain of temperatura with ice box and preservative