Sorbic acid gets its name from Sorbus aucuparia (rowan or mountain ash tree), because it is derived from the unripe berries of the tree. Our ash berry trees grow in Germany and the berries are best harvested after a sharp frost which starts off the bletting process and begins to break down the cell walls. Ideally the berries should be bletted, this is a process whereby the fruit is allowed to ripen beyond its current ripened state, leading to an increase in fruit sugars and beginning the process of breaking down the parasorbic acid and tannins. Ash berries contain naturally parasorbic acid which was first isolated through extraction. Once picked, the berries are crushed, then leached with water to produce a reddish juice, which is concentrated to syrup after evaporation. Parasorbic acid is separated from the syrup by steam distillation in the presence of acid.