Varying the aforementioned conditions during incubation changes the ratio
between the rods and the cocci as follows:
1. Incubation time: A shorter incubation time, which means a lower acidity,
will cause too high a proportion of cocci. Transferring a yogurt
starter repeatedly after short incubation times during the production of
the starter may cause also the rods to disappear from the culture. Conversely,
long incubation times will cause an increasing preponderance
of the rods.