OK, I gotta ask, what is BBGA?
Chef Isa, you may want to increase the water in your recipe. You have about 57% hydration and you could up it to 62% or more to give the yeast a bit more room to do it's work.
Winona, many supermarket flours contain malt which amongst other things, helps to promote browning. Other flours don't (If I remeber, KA flour does not I think) and that might be a problem for you. Also, in the fermenting process natural sugars are developed which add flavor and color. You may want to look at the fermenting times and temperatures you are using.
Do you check for doneness by taking the bread's temperature? About 200 degrees internal temperature is enough. Guestimating or baking for the time prescribed by the recipe with an oven that might be out of calibtration will give you trouble - especially with a thin bread like a baguette.
Jock |