Hi. New baker here. I've been baking for a few months now. I baked this simple white bread from a Bertinet video. The bread taste delicious, but it's yellowish inside. When my guest asked why it was yellow I had no answer! It's a white bread recipe with 4 ingredients. Flour , water, yeast, salt. Is this normal ? My guess was that the yeast imparted the color, but it was just a guess.