Unexpected effect of baking soda

As as apprentice sorceror I feel obliged to make some experiment, once in a while :-)

This time around the object of my study was sodium bicarbonate (baking soda). I prepared a poolish with 10 gr of rye starter, 60 gr of white flour and 60 gr of water with 0.6 gr of bicarbonate dissolved within. The poolish doubled in the usual amount of time, but contrary to the usual it had a thicker consistency than when I prepared it (generally it's much thinner).

Next I made a biga with 10 gr of rye starter, 60 gr of white flour and 30 gr of water with 0.3 gr of bicarbonate dissolved in it. After 10 hours the biga had doubled and it hadn't minimally teared nor lost consistence.

Even the taste of the preferments was completely different: acidity was completely absent, as expected. They were totally tasteless.

In short: bicarbonate seems to have completely stopped the proteolytic activity typical of rye starters, even at that very low (0.5%) concentration.

I wonder if this is due to

-reduced acitity (pH 6.1 in the poolish), but protease should still work even at such a neutral pH as far as I know

-some impurity in the soda? Maybe some trace of ordinary sea salt? Sea salt is known to block protease.

-some real protease-blocking property of baking soda?

At the current state of things it seems that baking soda could be used to permit longer fermentations.

I'd really like to read your opinions.

  Nico