Recently I finished my 6th batch of beer, the first top-fermenting one (wheat beer). The yeast is from a commercial brewery nearby, so I don't know its exact type. Usually my bottle fermentation takes place at cellar or even room temperatures and I put the bottles in the fridge a couple of days before drinking. For bottom-fermenting yeast this worked nicely so far.
The bottle fermentation and storage of the new batch:
Half of the batch (A): 4 weeks at room temperature
Half of the batch (B): one week at room temperature, 3 weeks in the fridge
Half B tastes really good, Half A shows a distinct sour overtone. Is top-fermenting yeast more prone to building undesired byproducts during bottle fermentation than bottom-fermenting yeast? Or could the summer temperatures be the reason? (Cellar: 10°C in the winter, 15°C in the summer, Room: 18°C in the winter, 23°C in the summer)