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I am frequently buying raw milk in bottle, which needs to be boiled for pasteurization. So far I always poured it in a pot, boiled it, and transferred it to a clean bottle after.

Since my old supplier dried up I need to travel a bit to get it, so I am thinking about ways to preserve it a bit longer, preferably 2-4 weeks in the fridge.

Would it be a good idea to put the glass bottles as they are in a water bath and wait until the milk starts bubbling? This way I won't need to do all the transfers and there won't be any air contact, it would be basically water bath canned. Would it hold for 2-4 weeks this way in my 4C° fridge? Any downsides?

I was also considering pressure canning, but I think this would be over kill for what I am trying to achieve here, which is slightly longer fridge life.

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You're in luck!

High-temperature short-time (HTST) pasteurisation for milk can be done at 71.5 °C (160.7 °F) for 15 seconds and extends milk's shelf life to about 2 weeks. So if you can get a thermometer you don't need to wait for milk to bubble.

It's also possible to use a sous vide method; according to this guide 65°C for 30 minutes. Again, it's very important all the milk reaches this temperature and stays constant during the process. In this case the lower temperature is possible because the exposure time is longer. After 30 minutes, cool it as quickly as possible to 4°C.

To extend the shelf life to ~3 months you need ultra-high-temperature (UHT) pasteurisation (135 °C (275 °F) for 1–2 seconds) but that might be more difficult to control; you need to make sure that all the milk reached the temperature and stay there for that amount of time. I'm not sure this process is possible with home equipment.

Make sure to sterilise your containers prior to adding the milk, to avoid other contaminants.

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  • What if I pasteurize in the bottle and don't open it? This will probably increase the shelf life in the fridge? Also what about sous vide pasteurizetion at 64C° for 30min? Is this just as good as the other versions?
    – user1721135
    Mar 5, 2020 at 15:41
  • You shouldn't play around with the temperature if you plan to keep the milk for that long; some pathogens only die at 65ºC, which is the temperature recommended by this guide sous-vide.cooking/how-to-pasteurise-milk
    – Luciano
    Mar 6, 2020 at 9:25
  • Maybe Ill sous vide half of it, which I will use during week 1 and HTST the other half, which will be used during the second week. And I will be able to compare, if there is a difference at all. Wouldn't the lack of oxygen (closed bottle) and the low temp. significantly increase the shelf life? Can't find information on that.
    – user1721135
    Mar 6, 2020 at 10:00
  • @user1721135 well 2 weeks is already significant... Fridge temperature is also not very constant, and milk quality will degrade by being exposed to light, so it's not just about contaminants and pathogens. Have you considered freezing some of the milk?
    – Luciano
    Mar 6, 2020 at 10:33
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    I have, although I don't have much space in the freezer. Maybe I should cut my target shelf life to 2 weeks max and freeze half. I have in the past, always kept boiled milk for 2 weeks without any special measures, like boiling in the unopened bottle and I have never had a problem, but right now, I want to be sure, since my wife is pregnant and we can't afford any experiments. Maybe I should just target 1 week and freeze the rest to be on the safe side.
    – user1721135
    Mar 6, 2020 at 10:43
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No, you can't. There is no approved safe process for home canning any kind of dairy.

Sure, there are industrial ways to preserve milk and other dairy-containing food for that long, but they have different security regulations, and are able to follow different processes which you cannot ensure in a home kitchen.

As always with food safety, no matter what you do at home, you cannot prove that it is safe.

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  • I am not actually planning on canning it and keeping it at room temperature, rather I want to increase its fridge life a bit. Cooking it in the closed bottle should be helpful for this? Like it is helpful for everything? I don't want to keep it for months, just for weeks.
    – user1721135
    Mar 6, 2020 at 10:01
  • The problem is that it is impossible to predict how long it will keep. Food safety is a promise made to you by an official agency who has extensively tested a given process and found out that, when followed with reasonable precision, it always gives a result where the bacterial load is low enough. Anything for which this promise doesn't exist, is by definition unsafe. For your plan, sure, it is clear that boiling will extend the fridge life compared to nonboiling - but you can't know if it will extend it by an hour, a week or a month.
    – rumtscho ♦
    Mar 6, 2020 at 10:39
  • Yeah, I don't want any experiments right now. Maybe I should just stick to 1 week shelf life to be on the safe side.
    – user1721135
    Mar 6, 2020 at 10:44

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