There once was a Polish movie made in the Communist times. Sugar was famously adulturated then - so a famous line from the movie had the character measuring "the sugar (content) in the sugar".
This Duo translation to English works of it's a science experiment.
usually they measure sugar in the milk, not "the sugar"
Could as well be the level of carbohydrates in the milk, aka "the sugar".
Exactly. The dative case in der Milch indicates that the object of the measurement is the sugar contained in the milk (which it naturally does without adding any).
"which it naturally has (not 'does') without adding any" = lactose
But the problem is, that the only carbohydrate in milk is lactose
(= milk sugar = Milchzucker). Other carbohydrates do not exist in milk. (;
How could I apply the genitive case in this sentence?
why not 'we measure the sugar . . .' ?
and if we wanted to say measuring the sugar into the milk.. ?
I think that would be "Wir messen den Zucker ins Milch."
Then you would measure the sugar "in die Milch hinein" and that is not possible.