Questions & Answers about Тесто начали складывать каждый час.
Russian often uses a 3rd person plural past verb with no stated subject to mean some unspecified people did it.
So начали here means something like they started, where they is indefinite: the bakers, the workers, people in general, etc.
This is called an indefinite-personal construction. English may translate it as:
- They started folding the dough every hour.
- or, more passively, The dough started being folded every hour.
But in Russian, the verb is still grammatically plural active.
Тесто is the direct object, so it is in the accusative case.
However, for inanimate neuter singular nouns, the accusative form is identical to the nominative. So:
- nominative: тесто
- accusative: тесто
That is why the form does not visibly change.