I recently did some whole wheat sourdough loaves that I discovered to be very sour.

The starter that I'm using in the levain is relatively new - as the whole wheat loaves were only
my second batch of sourdough. But thinking back I was in a rush when making the levain and I used the
starter straight from the refrigerator... it hadn't been replenished and hadn't been brought up to room temp.
I just used 2 tablespoons worth, dissolved and worked into the rest of the leavain to then sit overnight.

The resulting loaves are noticeably sour... much more so than using the same starter for a levain just the week before. The major difference would be that on the earlier less sour loaves I had refreshed the starter at least 8 hours prior and I added it to the levain when it was at room temp.

The other major difference would be that the others were white flour with a small addition of rye. Where as the wheat bread was a larger portion of wholewheat and white.

What are you thoughts?

Does it stand to reason that it was the starter? (eg. not being room temp/refreshed)

or

Was it perhaps some interaction with the whole wheat that made it more sour?

or

A combination of all of the above?

Best regards,
Luc