英语时差：白兰地是如何做出来的（上）

Making wine is a biological process. Live yeast added to grape juice digests the juice’s sugar giving off alcohol as a byproduct. How much alcohol is produced depends on how much sugar the juice starts with. But eighteen percent alcohol is about as strong as any wine can get before the yeast poisons itself and the fermentation stops. Brandy begins as wine but is then distilled, raising the alcohol concentration to forty or fifty percent–well above the level that would kill any yeast. To see how distillation works, picture steam from a kettle hitting a cold windowpane, where it condenses and drips off. The water dripping off is called “distilled water,” which is different from tap water because it no longer contains the salts and minerals with much higher boiling points, which were left behind when the water in the kettle turned to steam.