Originally Posted by Oldnastingham
Is it possible for Brett to occur naturally? I've made three batches using Wyeast4766 and unfiltered, organic juice. I really enjoy the way it turns out but friend who's sampled the same batches tells me he thinks it is "growing" characteristic claiming it is stronger each time he tastes it. I have cold crashed and kegged each batch. The last 5 gallons lasted about 10 days before it was gone and I definitely enjoyed the last bit. My other ciders with different juices and yeasts don't have this, so by deduction it has to be the yeast or the juice, obviously. My thought is the juice, wouldn't the yeast people advertise some sort of Brett qualities with this strain?
Brett was almost certainly in the juice unless you used a campden tablet or pasteurized the juice.
It is possible that the brett built up and is working post fermentation, but it wouldn't be a noticeable difference in 10 days.