Question for you sour dough guys

[bortz]

I captured a good wild yeast in my flour after 2 attempts at the wild yeast method.  I thought I had a good fermentation going. I was feeding my yeast every day with a 50/50 mix of flour and bottled water. I was seeing some bubbling activity after about the third day. I decided to test it out by making a loaf of bread machine bread.  The bread turned out with no rise and no holes but boy was it tasty.  But man, the thing felt like it weighed 10 pounds! I asked a female coworker where I could have went wrong and she said that the yeast wasn't active enough. Then I told here after some discussion, that I was using normal bleached white flour to make my wild starter. She said that was my problem- I should be using unbleached flour as the bleaching process is keeping my yeast from reaching it's full potential.
She also said I can get sour dough starter in our local supermarket. I saved some of my starter in case I can use it on unbleached flour and try again if needed.  Is she right about the unbleached flour and should I give up this method of trying to capture wild yeast and just go out and buy some of this sour dough starter?

[SteveB]

It is generally recommended that one use organic whole grain flour (wheat or preferably rye) when attempting to start a sourdough culture.  Using organic whole grain assures that the bran, which is covered with viable wild yeast, is present in the starting mixture.  The bran also provides minerals for the yeast's growth.  White flour is composed of the endosperm only (no bran) and therefore has a significantly lower concentration of indigenous wild yeast.  This would make the creation of a sourdough culture starting with white flour considerably more problematic.  Once the culture is viable, one can then switch over to white flour for feeding the culture.