When I buy coffee (either decaf or regular) at the convenience store and add 1/2 & 1/2, it lasts for several days and several re-heatings without curdling.

BUT when I make Keurig-type coffee using ANY of several different brands I buy at the supermarket, my coffee won't last until the next day and reheating. It will curdle overnight.

So, does the coffee in the Keurig-type cups just end up having a lot more acid in it from their manufacturing process?

Might it help with my Keurig-type coffee at home if I used the little 1/2 & 1/2 containers that a typical convenience store carries? I know the chemistry in those little containers is different so that they don't curdle as easily when left out. (Hence the difference in taste vs regular chilled 1/2 & 1/2). Maybe they are made with an intentional alkali Ph?


The little 1/2 & 1/2 containers are ultra-pasteurized, so that they can be stable at room temperature. Ultra-pasteurized milk products will not curdle. This is why you cannot make cheese with them.

It is also possible that the Keurig coffee, being better roasted and sealed, is more acidic, but it is far more likely the UP milk. You can test this by finding UP 1/2 & 1/2 at your supermarket in a carton, and comparing.

As a side note, I do find it pretty horrifying that you are making coffee, putting cream in it, and reheating it several days later. Maybe you could consider making a fresh pot?

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