Coopers are famous for this process which leaves a natural residue of yeast during maturation and gives a cloudy appearance with an enhanced flavour. Coopers Sparkling Ale is brewed and fermented using a unique method of top fermentation and natural bottle conditioning. Coopers Ales and Stout are naturally bottle conditioned, resulting in a characteristic fine sediment forming on the base of the bottle. This sediment is completely natural and can be gently mixed before drinking or poured carefully leaving the sediment in the bottle.